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  • 1.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design2016In: Proceedings of the 9th FPNI Ph.D. Symposium on Fluid Power (FPNI2016), American Society of Mechanical Engineers , 2016, article id V001T01A041Conference paper (Refereed)
    Abstract [en]

    Hybridization of a vehicle’s drivetrain can in principle help to improve its energy efficiency by allowing for recuperation of kinetic energy and modulating the engine’s load. How well this can be realized depends on appropriate sizing and control of the additional components. The system is typically designed sequentially, with the hardware setup preceding the development and tuning of advanced controller architectures. Taking an alternative approach, component sizing and controller tuning can be addressed simultaneously through simulation-based optimization.

    The results of such optimizations, especially with standard algorithms with continuous design variable ranges, can however be difficult to realize, considering for example limitations in available components. Furthermore, drive-cycle based optimizations are prone to cycle-beating. This paper examines the results of such simulation-based optimization for a series hydraulic hybrid vehicle in terms of sensitivity to variations in design parameters, system parameters and drive cycle variations. Additional relevant aspects concerning the definition of the optimization problem are pointed out.

  • 2.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Component Sizing Study for a Light-Duty Series Hydraulic Hybrid Vehicle in Urban Drive Cycles2013Conference paper (Refereed)
    Abstract [en]

    With the focus on energy efficiency for many different kinds of vehicle applications,hybridization is considered a possible solution to reduce fuel consumption. While hybrid electric concepts are already available for passenger vehicles, and also considered for heavier applications, hybrid hydraulic alternatives have been mainly limited to the latter, which benefit most from the higher power density available. To study the different hybrid architectures and applications, a modeling framework for the system design is developed using the simulation tool Hopsan from Linköping University.  Previously,  the  model  of  a  series  hydraulic  hybrid  vehicle  was introduced, a light-duty vehicle simulated over two standard urban drive cycles, and its potential for further work established. In this paper, the model is extended by including a simple combustion engine power management to provide for more realistic propulsion of the hydraulic drivetrain, showing the potential to operate a series hydraulic hybrid vehicle’s engine in more efficient regions. Additionally, the design is studied concerning the effects of a variation of key component sizes on the accuracy and energy efficiency objectives. Instead of subjecting the system to (multi- objective) optimization, at this stage the individual component’s influence is studied, and the objectives are dealt with separately from each other to eliminate the need for compromise   between   them,   both   to   gain a better understanding of the interdependencies.

  • 3.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle2015Conference paper (Refereed)
    Abstract [en]

    Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.

  • 4.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle2018In: International Journal of Fluid Power, ISSN 1439-9776Article in journal (Refereed)
    Abstract [en]

    Hybridisation of hydraulic drivetrains offers the potential of efficiency improvement for on – and off-road applications. To realise the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process. Addressing component selection and control parameterisation simultaneously through simulation-based optimisation allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimisation framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance. A number of optimisation experiments for an on-road light-duty vehicle, focused on standard-drive-cycle-performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.

  • 5.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Modeling of a Series Hybrid Hydraulic Drivetrain for a Light-Duty Vehicle in Hopsan2013In: Conference proceedings: 13th Scandinavian International Conference on Fluid Power / [ed] Petter Krus, Magnus Sethson, Liselott Ericson, Linköping, Sweden: Linköping University Electronic Press, 2013, p. 107-112Conference paper (Refereed)
    Abstract [en]

    Hydraulic hybrids continue to receive attention as a possible solution in the search for improved fuel economy for different vehicle types. This paper presents a model for a series hydraulic hybrid light-duty vehicle, developed in the Hopsan simulation tool of Linköping University’s Division of Fluid and Mechatronic Systems (Flumes). Focusing on the hydraulic transmission which employs a pump control based on the hydraulic accumulator’s state-of-charge (SoC), several simplifications were made, especially concerning mechanical components. Simulation over two urban standard cycles shows promising results concerning dynamic performance and energy recuperation potential, provided sufficient component sizing to compensate for the mechanical limitations. This paper lays the foundation for both a further refined model - suitable for optimizing the full drivetrain, including component sizing and controller parameterization - and the development of comparable models for parallel and power-split hybrid architectures.

  • 6.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle2014In: PROCEEDINGS OF THE 8TH FPNI PH.D SYMPOSIUM ON FLUID POWER, 2014, ASME Press, 2014, p. V001T03A004-Conference paper (Refereed)
    Abstract [en]

    Amongst the hybrid vehicle propulsion solutions aiming to improve fuel efficiency, hybrid electric solutions currently receive most attention, especially on the market. However, hydraulic hybrids are an interesting alternative, especially for heavier vehicles due to higher power density which is beneficial if higher masses are moved. As a step towards a comprehensive design framework to compare several possible hydraulic hybrid architectures for a specified application and usage profile, the model of a series hydraulic hybrid vehicle was previously introduced and initially studied concerning component sizing for an exemplary light-duty vehicle in urban traffic. The vehicle is modeled in the Hopsan simulation tool. A comparably straight-forward engine management is used for the vehicle control; both pump and engine controls are based on the hydraulic accumulator’s state-of-charge. The model is developed further with respect to the accumulator component model. Based on that, the influence of several system and component parameters, such as maximum system pressure and engine characteristics, as well as controller parameters on the vehicle’s performance is analyzed. The goal is to allow for more understanding of the system’s characteristics to facilitate future optimization of the system.

  • 7.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Full Vehicle Simulation of Forwarder with Semi Active Suspension using Co-simulation2016Conference paper (Refereed)
    Abstract [en]

    A major concern in the forest industry is impact on the soil caused by forest machines during harvesting. A six-wheel pendulum arm forwarder is being developed. The new forwarder aims at reducing soil damage by an even pressure distribution and smooth torque control and thereby also improving the working environment. The suspension contains pendulum arms on each wheel controlled by a hydraulic load sensing system in combination with accumulator.

    A natural approach is to model each part of a system in the bestsuited software. In this case, the hydraulic system is modelled in the Hopsan simulation tool, while the vehicle mechanics is modelled in Adams. To understand the whole system it is necessary to simulate all subsystems together. An open standard for this is the Functional Mock-up Interface. This makes it possible to investigate the interaction between the hydraulic system and the multi-body mechanic model.

    This paper describes how different simulation tools can be combined to support the development process. The technique is applied to the forwarder’s pendulum suspension. Controllers for height and soil force are optimized to minimize soil damage and maximize comfort for the operator.

  • 8.
    Dell' Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Henriksen, Fredrik
    Skogforsk, the Swedish Forestry Research Institute of Sweden.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Modelling and experimental verification of a secondary controlled six-wheel pendulum arm forwarder2015In: the 13th European Conference of ISTVS / [ed] Roberto Paoluzzi, 2015, p. 1-10Conference paper (Refereed)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines duringharvesting, where damages can have a negative impact on e.g. further growth. One of the main reasons is wheel slip.Another concern is the working environment of the operator due to the harsh ground in the forest. Both these issueshave a negative impact on productivity. An attempt to overcome these challenges is made within a collaborative researchproject, which among others also includes Linköping University, where a new six-wheel pendulum arm forwarder isbeing developed. The new forwarder aims at reducing the soil damage by an even pressure distribution and smooth torquecontrol, as well as increased damping of the complete chassis, and thereby improving the working environment. This ispossible since each wheel, driven by its own hydraulic motor, is attached to a pendulum arm allowing to control the heightof each wheel independently of each other. The forwarder has a total maximum weight of 31 tonnes, including 14 tonnesmaximum load. It consists of two steerable joints and is driven by a 360 bhp diesel engine. The transmission consists oftwo hydraulic pumps and six hydraulic motors.This paper deals with the development of the driveline and presents the first experimental tests of the implementedcontrol strategies, where a secondary control approach is chosen for its ability to individually control the torque on eachwheel. The control strategies, presented in the paper, include pressure control, velocity control of the vehicle and ananti-slip controller. To support the development of the control strategies, models of the vehicle and hydraulic subsystemsare derived. The aim with this paper is to verify the concepts on the actual vehicle. The initial results are promising,indicating that the suggested concept is feasible.

  • 9.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Flow Pulsations in Fluid Power Machines - a Measurement and Simulation Study2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stricter requirements for better working environment involve noise and vibration control of hydraulic machines. The operational conditions for hydraulic machines, such as pressure and rotational speed, are also increasing and this makes it even more difficult to develop a quiet, vibration-free machine due to the interdependence between noise and escalating operational conditions. The thesis investigates machines working in different driving modes and under different operational conditions.

    A so-called cross-angle is proposed for motor as well as pump/motor applications with variable displacement angles. The cross-angle is intended to reduce the overall noise level in the machine's working area. Other noise reduction features are also considered for machines working in different modes.

    To facilitate the system integrator's ability to design quiet systems, methods to determine the source flow and source impedance of the machine are essential. The source flow is assumed to be created at the valve plate and the internal impedance related to the high pressure port are completely independent of the rest of the system. Knowledge of these properties makes it possible to foresee the noise properties of a system already on the design phase. A novel source flow measurement method, the source admittance method, is investigated here. The method is considered to be robust and easy to use to suit industry requirements.

    List of papers
    1. The source admittance method A new measurement method for hydrostatic pump flow pulsation
    Open this publication in new window or tab >>The source admittance method A new measurement method for hydrostatic pump flow pulsation
    2006 (English)In: Proc. of the 4th FPNI - PhD Symposium Sarasota, Vol 1, Sarasota: Coastal Printing , 2006, p. 297-309Conference paper, Oral presentation only (Refereed)
    Abstract [en]

    Two main drawbacks with hydraulic systems are noise and vibrations, mainly created from flow pulsations in positive displacement pumps. The flow ripple can be divided in two parts; kinematic and compressible. Kinematic flow ripple is created due to the limited number of pumping elements. Compressible flow ripple is created due to cornpressibility effects in the pumping chambers and is the dominating effect at high pressures. There are well proven methods to decrease noise in specific operation conditions, but there is an urgent need for new techniques in machines working under varying operation conditions. There is also a need for improved measurement methods to be used in product development and to judge new inventions to decrease noise.

    Simulation techniques are useful in the early stages of the development process. There are useful and accurate simulation models capable of predicting source flow ripple in hydrostatic pumps and thereby useful for optimisation purposes. Simulation results are, however, of less practical use before they are experimentally verified . The experimental methods must be simple and straightforward if they are to be accepted in industry.

    This paper describes a new method to measure source flow. It is called the source admittance method. Compared to earlier methods such as the two-microphone method, the main benefit is that there is no need for a model of the outlet channel - the source flow is measured through an additional pressure transducer inside the pump. The method works very well with a tested fixed bent-axis pump with a rather simple outlet channel. Experiments have also been performed with a variable in-line pump with added complexity to the out let channel. Although the overall impression is positive, these experiments show that the method needs to be further to be used for such machines. In both cases, the new method is compared with earlier verified simulation models and with measurements based on the two-microphone method. Apart from the mentioned discrepancies in a narrow frequency range, agreement is very good.

    Place, publisher, year, edition, pages
    Sarasota: Coastal Printing, 2006
    Keywords
    Flow pulsations, measurement, hydrostatic pump, two-microphone method
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-36611 (URN)31745 (Local ID)1-4243-0499-7 (ISBN)31745 (Archive number)31745 (OAI)
    Conference
    4th FPNI - PhD Symposium Sarasota. Sarasota, Fl, US, June 2006.
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20
    2. The source admittance method for pumps with complex outlet channels
    Open this publication in new window or tab >>The source admittance method for pumps with complex outlet channels
    2007 (English)In: Proc. of the 10th Scandinavian International Conference on Fluid Power (SICFP'07), vol 1, Tampere: Tampere University of Technologi , 2007, p. 279-293Conference paper, Published paper (Refereed)
    Abstract [en]

    The source admittance method offers a new way to measure flow ripple. Compared to earlier methods such as the two-microphone method, the main benefit is that there is no need for a model of the outlet channel - the source flow is measured through an additional pressure transducer inside the pump. This makes the source admittance method easier to use and less modelling skill is needed. Furthermore, the method is more reliable because the somce flow is measured, i.e. pressure at the creation spot, directly. In earlier studies, the method proved to work very well for pumps with simple discharge channels but less well for pumps with complex discharge channels.

    The experimental test object is a pump with a simple outlet channel. Its internal impedance can easily be changed in a controlled manner; complexity can thus be added step by step. The paper contributes to the understanding of how complexity of the pump's discharge channel influences the usefulness of the source admittance method.

    Place, publisher, year, edition, pages
    Tampere: Tampere University of Technologi, 2007
    Keywords
    Fluid power
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-40967 (URN)54782 (Local ID)978-952-15-1761-7 (ISBN)54782 (Archive number)54782 (OAI)
    Conference
    10th Scandinavian International Conference on Fluid Power (SICFP'07). Tampere, Finland, May 2007.
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20
    3. Flow pulsation reduction for variable displacement motors using cross-angle
    Open this publication in new window or tab >>Flow pulsation reduction for variable displacement motors using cross-angle
    2007 (English)In: Power Transmission and Motion Control (PTMC 2007) / [ed] D. N. Johnston, and A. Plummer, Essex: Hadleys Ltd , 2007, p. 103-116Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper considers using the cross-angle in variable displacement hydraulic machines. The cross-angle is a fixed displacement angle around the axis perpendicular to the normal displacement direction. The cross-angle changes the angles to the pistons top and bottom dead centres as a function of the fraction of displacement in such a way that the valve plate timing is varied and different pre-compression and decompression angles are obtained. A non-gradient optimisation technique, the Complex method, is used together with a comprehensive simulation model in order to find the optimal cross-angle for a variable displacement hydraulic motor. The paper shows that the cross-angle can be used to reduce noise in variable displacement motors. One issue that makes the motor application more difficult is the increased dependence between outlet and inlet flow ripple which is not found in pump applications. Furthermore, the paper discusses how to use the cross-angle for machines which can work both as a motor and a pump.

    Place, publisher, year, edition, pages
    Essex: Hadleys Ltd, 2007
    Keywords
    Cross-angle flow pulsations noise hydraulic pump hydraulic motor
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-40965 (URN)54778 (Local ID)978-0-86197-140-4 (ISBN)54778 (Archive number)54778 (OAI)
    Conference
    Power Transmission and Motion Control (PTMC 2007), 12-14 September, Bath, UK
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20
  • 10.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Movement of the swash plate in variable in-line pumps at decreased displacement setting angle2013Conference paper (Refereed)
    Abstract [en]

    Emitted noise is one of the biggest drawbacks of using fluid power systems. By using variable pump/motor unitsthe fluid power system architecture is more flexible and efficiency is drastically improved. However, the noise level atfragment displacement angles is not proportional to the power output. The noise level is rather increased with decreasedsetting angle. Studies by other researchers show increased flow pulsation at small displacement due to the controller’sdynamic response.In this paper a simulation model to understand the pump/motor behaviour at variable displacement angles is presented.The model includes the important forces created due to pressure built up in the pump and acting on the swash plate. Thecontrol valve and actuator are modelled to enable investigations of the oscillations on the swash-plate. The open loopsystem is compared to the closed loop system, where internal forces from the pistons on the swash plate and pressureexcitation are fed back by the controller.The pulsating pressure in the control actuator has no major impact on the flow and force pulsations. The swash plateoscillations due to the internal piston forces, however, are significant and will affect the outlet flow pulsations. Thepulsation is significant but will not have a major impact on valve plate designs for conventional pumps and motors.

  • 11.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    On Fluid Power Pump and Motor Design: Tools for Noise Reduction2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Noise and vibration are two of the main drawbacks with fluid power  systems. The increasing requirements concerning working environment as well as machines' impact on surroundings put components and systems to harder tests. The surrounding machines, e.g. combustion engines, have made considerable progress regarding the radiated noise. This allows the fluid power system's noise to become more prominent. Noise from fluid power systems has been a research topic for several decades and much improvement has been achieved. However, considerable potential for improvement still remains.

    In addition to the legislation governing working environment, the machines tend to be used as more multi-quadrant machines, which require more flexible noise reduction features. One of the main benefits with fluid power is the high power density. To increase this value even more, the system's working pressure increases, which correlates with increased noise level.

    The main source of noise is considered to be the pump and motor unit in the fluid power system. The noise can be divided into two parts: fluid-borne noise and structure-borne noise. The fluid borne noise derives from flow pulsation which is subsequently spread through pipeline systems to other parts of the fluid power systems. The flow pulsation is created due to the finite stiffness of oil and the limited number of pumping elements. The structure-borne noise generates directly from pulsating forces in the machine. The pulsating forces are mainly created by the pressure differences between high and low pressure ports.

    Effective and accurate tools are needed when designing a quiet pump/motor unit. In this thesis simulation based optimisation is used with different objective functions including flow pulsation and pulsating forces as well as audible noise. The audible noise is predicted from transfer functions derived from measurements. Two kinds of noise reduction approaches are investigated; cross-angle in multi-quadrant machines and non-uniform placement of pistons. The simulation model used is experimentaly validated by source flow measurements. Also, source flow measurements with the source admittance method are investigated.

    In addition, non-linear flow through a valve plate restrictor is investigated and the steady state restrictor equation is proposed to be extended by internal mass term.

    List of papers
    1. Flow pulsation reduction for variable displacement motors using cross-angle
    Open this publication in new window or tab >>Flow pulsation reduction for variable displacement motors using cross-angle
    2007 (English)In: Power Transmission and Motion Control (PTMC 2007) / [ed] D. N. Johnston, and A. Plummer, Essex: Hadleys Ltd , 2007, p. 103-116Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper considers using the cross-angle in variable displacement hydraulic machines. The cross-angle is a fixed displacement angle around the axis perpendicular to the normal displacement direction. The cross-angle changes the angles to the pistons top and bottom dead centres as a function of the fraction of displacement in such a way that the valve plate timing is varied and different pre-compression and decompression angles are obtained. A non-gradient optimisation technique, the Complex method, is used together with a comprehensive simulation model in order to find the optimal cross-angle for a variable displacement hydraulic motor. The paper shows that the cross-angle can be used to reduce noise in variable displacement motors. One issue that makes the motor application more difficult is the increased dependence between outlet and inlet flow ripple which is not found in pump applications. Furthermore, the paper discusses how to use the cross-angle for machines which can work both as a motor and a pump.

    Place, publisher, year, edition, pages
    Essex: Hadleys Ltd, 2007
    Keywords
    Cross-angle flow pulsations noise hydraulic pump hydraulic motor
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-40965 (URN)54778 (Local ID)978-0-86197-140-4 (ISBN)54778 (Archive number)54778 (OAI)
    Conference
    Power Transmission and Motion Control (PTMC 2007), 12-14 September, Bath, UK
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20
    2. On optimal design of hydrostatic machines
    Open this publication in new window or tab >>On optimal design of hydrostatic machines
    2008 (English)In: Proceedings of the 6th International Fluid Power Conference, IFK, Vol WS, 2008, p. 273-286Conference paper, Published paper (Refereed)
    Abstract [en]

    Noise is a well known challenge for hydraulic systems and hydrostatic machines is one of the largest noise contributors in a hydraulic system. The noise from the machine originates from flow pulsations in the discharge and suction ports, as well as pulsations in piston forces and bending moments. To the design a quite hydraulic machine is a difficult task where many different objectives need to be considered. This paper presents a generic method for how optimization based on simulation models could be used to design quieter hydraulic machines. In order to stay competitive on a global market an efficient product development process is essential for all manufacturing industries. By using simulation-s tools in the design process, the product can be analysed before the actual product is manufactured. Furthermore, in order to find an optimal design of the machine with respect to noise, a comprehensive dynamic simulation model is needed. The model contains all important noise contributors. In the paper, the simulation models are used together with a non-gradient optimization method in order to find the best possible design. A vital part when using optimization to support design is always to formulate the objective function. As mentioned above, noise is generated from different sources and all these sources need to be considered when the objective function is formulated. For example a design that minimizes flow pulsations in the suction port will surely perform badly in some other objective. Therefore noise minimization could be looked upon as a typical multi-objective optimization problem. It is also not evident how the different objective should be ranked because the observed noise level is strongly depending on the system in which the machine is to be used. The paper also considers whether the objective function should be formulated in time or frequency domain. Traditionally, simulation of machine performance is conducted in the time domain, but the human ear hears noise in the frequency domain and perceives high and low frequencies differently. Furthermore, transformation from piston forces into emitted noise is much higher at high-frequency content than low-frequency content. This makes it natural to formulate the objective function in frequency domain, which raises the question of how the different harmonic should be ranked. In the paper a number of different approaches to formulate the objective function is presented and evaluated. The objectives considered are flow pulsation in both discharge and suction ports, as well as pulsation in piston forces and bending moments. Furthermore, the objectives are studied in both time and frequency domain. The design application is a variable hydraulic machine of bent axis type with nine pistons, which is operated both as a pump and a motor. However, the methods presented in the paper could be applied to other types of hydraulic machines as well. 

    Keywords
    Fluid power, pump, motor, noise, optimisation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-42260 (URN)62133 (Local ID)62133 (Archive number)62133 (OAI)
    Conference
    6th International Fluid Power Conference, March 31-April 2, Dresden, Germany
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20Bibliographically approved
    3. Optimisation of Structure Borne Noise and Fluid Borne Noise from Fluid Power Pumps and Motors
    Open this publication in new window or tab >>Optimisation of Structure Borne Noise and Fluid Borne Noise from Fluid Power Pumps and Motors
    2009 (English)In: Proc. of the 11th Scandinavian Fluid Power Conference, 2009Conference paper, Published paper (Other academic)
    Abstract [en]

    Structure borne noise in a machine rises from piston force and bending moments among others. This noise arises directly from the pump shell. In this study, a transfer function methodology is employed for mapping simulated internal pump dynamics, such as piston forces and bending moments, on to structure borne noise. Using these transfer functions, it is possible to predict how, for instance, changed valve plate timing affects simulated piston forces and bending moments and in turn how that will affect audible noise. Hence, it is possible to design an objective function that directly reflects audible noise. The transfer functions are experimentally obtained and are valid for a specific machine shell and to some minor extent the room’s acoustical properties. Also, fluid borne noise is important to consider when designing a quiet machine. Fluid borne noise arises mainly from flow pulsation created inside the machine.

    Simulation of the internal pump dynamics, and optimisations, are carried out using a pump model developed in the simulation tool HOPSAN. The design application is a hydraulic machine of bent axis type with seven pistons. The theory outlined and the method proposed in the paper can also be applied to other types of hydraulic machines. The paper shows how both structure borne noise and fluid borne noise can be considered using multi-objective optimisation. The paper shows how different noise reduction features affect the sound pressure level and the flow pulsation. The paper also compare the pump and motor case.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-73977 (URN)
    Conference
    The 11th Scandinavian Fluid Power Conference, June 2-4, Linköping, Sweden
    Available from: 2012-01-18 Created: 2012-01-18 Last updated: 2017-12-20Bibliographically approved
    4. Noise reduction by means of non-uniform placement of pistons in a fluid power machine
    Open this publication in new window or tab >>Noise reduction by means of non-uniform placement of pistons in a fluid power machine
    2010 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    In conventional machines, the pulsations are periodic and originate from the uniform placement of a given number of pistons. This paper discusses the possibilities to introduce non-uniform placement of the pistons. The pulsations periodicity is thus changed, which can have a major impact on the noise level and how the noise is experienced. A number of approaches are presented, evaluated and ranked and the usefulness of the modifications is assessed. This study employs a transfer function methodology to map simulated internal pump dynamics, such as piston forces and bending moments, to audible noise. Using these transfer functions, it is possible for instance to predict how changed valve plate timing affects simulated piston forces and bending moments and in turn how this will affect audible noise. Copyright © 2009 by ASME.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-73978 (URN)
    Conference
    2nd Annual Dynamic Systems and Control Conference October 12-14, Hollywood, CA, USA
    Available from: 2012-01-18 Created: 2012-01-18 Last updated: 2017-12-20Bibliographically approved
    5. Measurement of Free Air in the Oil Close to a Hydraulic Pump
    Open this publication in new window or tab >>Measurement of Free Air in the Oil Close to a Hydraulic Pump
    2009 (English)In: JFPS International Journal of Fluid Power System, ISSN 1881-5286, Vol. 2, no 2, p. 39-44Article in journal (Refereed) Published
    Abstract [en]

    Noise is a well-known challenge in hydraulic systems and hydrostatic pumps are one of the largest noise contributors in a hydraulic system. The existing noise reduction features, such as pressure relief groove and pre-compression filter volume, are more or less dependent on the working condition. It is essential to know the amount of free air when designing a quiet pump; however, it is not evident how much free air the oil contains. The free air content is different if the suction port is boost pressured or self-priming. The amount of free air in a well-designed system can be as low as 0.5% while in others up to 10%.This paper uses the three-transducer method to measure the amount of free air in the oil. The oil's compressibility can be measured for different working conditions and the free air content can then be calculated. The pre-study is performed with an extensive simulation model. Various noise reduction features' sensitivity to free air content is considered.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-63018 (URN)
    Available from: 2010-12-09 Created: 2010-12-09 Last updated: 2017-12-20Bibliographically approved
    6. Unsteady Flow through Valve Plate Restrictor in a Hydraulic Pump/Motor Unit
    Open this publication in new window or tab >>Unsteady Flow through Valve Plate Restrictor in a Hydraulic Pump/Motor Unit
    2010 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Noise is a well known challenge in hydraulic systems. Hydrostatic machines are among the largest noise contributors in a hydraulic system.The noise from the machine originates from flow pulsations at the discharge and suction ports, as well as pulsations in piston forces and bending moments.

    This article investigates the dynamic behaviour of unsteady flow through a valve plate in an axial piston pump. The proposed extension of the steady state restrictor equation includes a dynamic internal mass term and a resistance. The results from 1D model are validated with a 3D CFD model. Different valve plates’ configurations and pump sizes are easily simulated with the two simulation models. The simulation results show very good comparison with experimental tests. The proposed method is verified with a hydraulic pump application but it can probably also apply for original restrictors too.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-73980 (URN)
    Conference
    2nd Annual Dynamic Systems and Control Conference October 12-14, Hollywood, CA, USA
    Available from: 2012-01-18 Created: 2012-01-18 Last updated: 2017-12-20Bibliographically approved
  • 12.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Project: Attenuation of pump flow pulsations by hydraulic RC filters2010Report (Other academic)
    Abstract [en]

    The work has been performed at Johannes Kepler University of Linz at the Institute of Machine Design and Hydraulic Drives. A novel method is to create a RC-type hydraulic filter between the pump and load. R stand for resistor and C for capacitor which creates a passive electrical low-pass filter. In hydraulic terms, the capacity of the filter is the cavity of the pump's delivery channel and the resistive part is the orifice which connects the pump to the external system. This system may not minimise the overall hydraulic noise however the attenuator's goal is to minimise the pulsations at the load.In the project a simulation model have been developed in HOPSAN. The flow pulsation created in the radial piston pump is extensively modelled. Furthermore, the RC-filter including the external system is modelled. The simulation model has been verified with some pressure pulsation measurements.The simulations show a reduction of the pressure pulsations at the load. However, the pressure drop associated with the superimposed flow variation is much smaller than predicted by the steady-state orifice equation. Further investigations and measurements need to be done do increase the accuracy of the orifice equation.

  • 13.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Swash Plate Oscillations due to Piston Forces in Variable In-line Pumps2014Conference paper (Other academic)
    Abstract [en]

    This study investigates the oscillations of swash plates caused by piston forces acting on the swash plate. Earlier investigations of variable axial piston pumps assume a fixed swash plate angle, i.e. the swash plate is fixed at different displacement angles. Under normal operating conditions, the swash plate is controlled by a hydraulic actuator which affects the swash plate. The presented models are able to separate different losses caused by the swash plate oscillations and the controller. The results show oscillations on the swash plate which affect both efficiency and flow pulsation and hence the noise level.

  • 14.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Dell' Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    MODELLING OF A SECONDARY CONTROLLED SIX-WHEEL PENDULUM ARM FORWARDER2015Conference paper (Refereed)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines during harvesting, where damage can have a negative impact on growth at replanting for example. Another concern is the working environment of the operator. Both these issues have a negative impact on productivity. A new six-wheel pendulum arm forwarder is being developed within a collaborative research project. The new forwarder aims to reduce soil damage by means of an even pressure distribution and smooth torque control. This paper presents the first step in the development of the driveline, where a secondary control approach is chosen for its ability to control the motion of each wheel individually. Simulation models of both vehicle and driveline have been constructed developed, partly for the development of the control strategy, and partly for evaluation. A speed control concept and a torque control concept have both been evaluated for different scenarios with regard to their ability to reduce wheel slip. Results have shown that a velocity control approach is more sensitive to kinematic model accuracy while wheel slip is handled automatically. A torque control approach is more robust towards model accuracy while the reduction of slip is dependent on an accurate model.

  • 15.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Dell'Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    An Electric Hydraulic Hybrid Light Vehicle with Energy Recovery2011In: 52nd National Conference on Fluid Power, Las, 2011, p. 741-749Conference paper (Refereed)
    Abstract [en]

    A three wheeled electric hydraulic hybrid vehicle with tiltingbody was built and tested at Linköping University as a partof a student project. The goal of the student project wasto design and fabricate an environmentally friendly vehicleto enter the Formula ATA Electric & Hybrid Italy 2009 competition.The design of the vehicle was based on the rulesand requirements of the competition. The vehicle was alsoprepared for a hydraulic recovery system which was laterimplemented on the vehicle. Hydraulic motor/pump unitsare used to brake and recover energy and to provide additionalboost during acceleration. The energy recovery storageis hydraulic gas accumulators, while the primary propulsionsystem is electrical with Li-Fe batteries. Gas accumulatorshave very high power density superior to electricalbatteries.In this paper, the design of the hydraulic recovery system isdescribed along with simulation and experimental results.The concept shows high potential and the tests show a20 % recovery of the kinetic energy by the hydraulic systemfor a given cycle.

  • 16.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Johansson, A.
    Pump and Motor Division, Parker Hannifin Corp., Flygmotorv. 2, 461 82 Trollhättan, Sweden.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Noise reduction by means of non-uniform placement of pistons in a fluid power machine2010Manuscript (preprint) (Other academic)
    Abstract [en]

    In conventional machines, the pulsations are periodic and originate from the uniform placement of a given number of pistons. This paper discusses the possibilities to introduce non-uniform placement of the pistons. The pulsations periodicity is thus changed, which can have a major impact on the noise level and how the noise is experienced. A number of approaches are presented, evaluated and ranked and the usefulness of the modifications is assessed. This study employs a transfer function methodology to map simulated internal pump dynamics, such as piston forces and bending moments, to audible noise. Using these transfer functions, it is possible for instance to predict how changed valve plate timing affects simulated piston forces and bending moments and in turn how this will affect audible noise. Copyright © 2009 by ASME.

  • 17.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Johansson, A.
    Pump and Motor Division, Parker Hannifin Corp., Flygmotorv. 2, 461 82 Trollhättan, Sweden.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Noise reduction by means of non-uniform placement of pistons in a fluid power machine2010In: Proceedings of the ASME Dynamic Systems and Control Conference 2009, DSCC2009, 2010, no PART B, p. 1293-1300Conference paper (Refereed)
    Abstract [en]

    In conventional machines, the pulsations are periodic and originate from the uniform placement of a given number of pistons. This paper discusses the possibilities to introduce non-uniform placement of the pistons. The pulsations periodicity is thus changed, which can have a major impact on the noise level and how the noise is experienced. A number of approaches are presented, evaluated and ranked and the usefulness of the modifications is assessed. This study employs a transfer function methodology to map simulated internal pump dynamics, such as piston forces and bending moments, to audible noise. Using these transfer functions, it is possible for instance to predict how changed valve plate timing affects simulated piston forces and bending moments and in turn how this will affect audible noise. Copyright © 2009 by ASME.

  • 18.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Johansson, Andreas
    Parker Hannifin AB.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    The source admittance method A new measurement method for hydrostatic pump flow pulsation2006In: Proc. of the 4th FPNI - PhD Symposium Sarasota, Vol 1, Sarasota: Coastal Printing , 2006, p. 297-309Conference paper (Refereed)
    Abstract [en]

    Two main drawbacks with hydraulic systems are noise and vibrations, mainly created from flow pulsations in positive displacement pumps. The flow ripple can be divided in two parts; kinematic and compressible. Kinematic flow ripple is created due to the limited number of pumping elements. Compressible flow ripple is created due to cornpressibility effects in the pumping chambers and is the dominating effect at high pressures. There are well proven methods to decrease noise in specific operation conditions, but there is an urgent need for new techniques in machines working under varying operation conditions. There is also a need for improved measurement methods to be used in product development and to judge new inventions to decrease noise.

    Simulation techniques are useful in the early stages of the development process. There are useful and accurate simulation models capable of predicting source flow ripple in hydrostatic pumps and thereby useful for optimisation purposes. Simulation results are, however, of less practical use before they are experimentally verified . The experimental methods must be simple and straightforward if they are to be accepted in industry.

    This paper describes a new method to measure source flow. It is called the source admittance method. Compared to earlier methods such as the two-microphone method, the main benefit is that there is no need for a model of the outlet channel - the source flow is measured through an additional pressure transducer inside the pump. The method works very well with a tested fixed bent-axis pump with a rather simple outlet channel. Experiments have also been performed with a variable in-line pump with added complexity to the out let channel. Although the overall impression is positive, these experiments show that the method needs to be further to be used for such machines. In both cases, the new method is compared with earlier verified simulation models and with measurements based on the two-microphone method. Apart from the mentioned discrepancies in a narrow frequency range, agreement is very good.

  • 19.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Johansson, Andreas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Optimisation of Structure Borne Noise and Fluid Borne Noise from Fluid Power Pumps and Motors2009In: Proc. of the 11th Scandinavian Fluid Power Conference, 2009Conference paper (Other academic)
    Abstract [en]

    Structure borne noise in a machine rises from piston force and bending moments among others. This noise arises directly from the pump shell. In this study, a transfer function methodology is employed for mapping simulated internal pump dynamics, such as piston forces and bending moments, on to structure borne noise. Using these transfer functions, it is possible to predict how, for instance, changed valve plate timing affects simulated piston forces and bending moments and in turn how that will affect audible noise. Hence, it is possible to design an objective function that directly reflects audible noise. The transfer functions are experimentally obtained and are valid for a specific machine shell and to some minor extent the room’s acoustical properties. Also, fluid borne noise is important to consider when designing a quiet machine. Fluid borne noise arises mainly from flow pulsation created inside the machine.

    Simulation of the internal pump dynamics, and optimisations, are carried out using a pump model developed in the simulation tool HOPSAN. The design application is a hydraulic machine of bent axis type with seven pistons. The theory outlined and the method proposed in the paper can also be applied to other types of hydraulic machines. The paper shows how both structure borne noise and fluid borne noise can be considered using multi-objective optimisation. The paper shows how different noise reduction features affect the sound pressure level and the flow pulsation. The paper also compare the pump and motor case.

  • 20.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Kärnell, Samuel
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Hochwallner, Martin
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Experimental Investigation of a Displacement-controlled Hydrostatic Pump/Motorby Means of Rotating Valve Plate2017In: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden, Linköping: Linköping University Electronic Press, 2017, Vol. 144, p. 19-27Conference paper (Refereed)
    Abstract [en]

    Interest in the control of variable fluid power pumps/motors has increased in recent years.The actuators used are inefficient and expensive and this reduces the variable units’ usability.This paper introduces displacement control of pumps/motors by means of a rotating valveplate. By changing the angle of the valve plate, the effective use of the stroke is changed. Therotating valve plate is experimentally verified by a modified in-line pump. In the prototype,the valve plate is controlled with a worm gear connected to an electric motor. The resultsshow potential for this kind of displacement control. However, the rotating valve plate createspressure pulsations at part-displacement due to the commutation being performed at highpiston speeds. If the piston speed and hence the flow from each piston is low, the pressurepulsation is acceptable.

  • 21.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Measurement of Free Air in the Oil Close to a Hydraulic Pump2009In: JFPS International Journal of Fluid Power System, ISSN 1881-5286, Vol. 2, no 2, p. 39-44Article in journal (Refereed)
    Abstract [en]

    Noise is a well-known challenge in hydraulic systems and hydrostatic pumps are one of the largest noise contributors in a hydraulic system. The existing noise reduction features, such as pressure relief groove and pre-compression filter volume, are more or less dependent on the working condition. It is essential to know the amount of free air when designing a quiet pump; however, it is not evident how much free air the oil contains. The free air content is different if the suction port is boost pressured or self-priming. The amount of free air in a well-designed system can be as low as 0.5% while in others up to 10%.This paper uses the three-transducer method to measure the amount of free air in the oil. The oil's compressibility can be measured for different working conditions and the free air content can then be calculated. The pre-study is performed with an extensive simulation model. Various noise reduction features' sensitivity to free air content is considered.

  • 22.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Measurement of Free Air in the Oil Close to a Hydraulic Pump2008In: Proceedings of the 7th JFPS International Symposium on Fluid Power, Vol. 3, Toyama: JFPS , 2008, p. 647-652Conference paper (Other academic)
    Abstract [en]

     Noise is a well-known challenge in hydraulic systems and hydrostatic pumps are one of the largest noise contributors in a hydraulic system. The existing noise reduction features, such as pressure relief groove and pre-compression filter volume, are more or less dependent on the working condition. It is essential to know the amount of free air when designing a quiet pump; however, it is not evident how much free air the oil contains. The free air content is different if the suction port is boost pressured or self-priming. The amount of free air in a well-designed system can be as low as 0.5% while in others up to 10%. This paper uses the three-transducer method to measure the amount of free air in the oil. The oil's compressibility can be measured for different working conditions and the free air content can then be calculated. The pre-study is performed with an extensive simulation model. Various noise reduction features' sensitivity to free air content is considered.

  • 23.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems.
    The source admittance method for pumps with complex outlet channels2007In: Proc. of the 10th Scandinavian International Conference on Fluid Power (SICFP'07), vol 1, Tampere: Tampere University of Technologi , 2007, p. 279-293Conference paper (Refereed)
    Abstract [en]

    The source admittance method offers a new way to measure flow ripple. Compared to earlier methods such as the two-microphone method, the main benefit is that there is no need for a model of the outlet channel - the source flow is measured through an additional pressure transducer inside the pump. This makes the source admittance method easier to use and less modelling skill is needed. Furthermore, the method is more reliable because the somce flow is measured, i.e. pressure at the creation spot, directly. In earlier studies, the method proved to work very well for pumps with simple discharge channels but less well for pumps with complex discharge channels.

    The experimental test object is a pump with a simple outlet channel. Its internal impedance can easily be changed in a controlled manner; complexity can thus be added step by step. The paper contributes to the understanding of how complexity of the pump's discharge channel influences the usefulness of the source admittance method.

  • 24.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Unsteady Flow through a Valve Plate Restrictor in a HydraulicPump/Motor Unit2012Conference paper (Refereed)
    Abstract [en]

    Noise is a well known challenge in hydraulic systems. Hydrostatic machines are amongthe largest noise contributors in a hydraulic system. The noise from the machine originatesfrom flow pulsations at the discharge and suction ports, as well as pulsations inpiston forces and bending moments. This article investigates the dynamic behaviour ofunsteady flow through a valve plate in an axial piston pump. The proposed extension ofthe steady state restrictor equation includes a dynamic internal mass term and a resistance.The results from 1D model are validated with a 3D CFD model. Different valveplates’ configurations and pump sizes are easily simulated with the two simulation models.The simulation results show very good comparison with experimental tests. Theproposed method is verified with a hydraulic pump application but it can probably alsoapply for original restrictors too.

  • 25.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Unsteady Flow through Valve Plate Restrictor in a Hydraulic Pump/Motor Unit2010Manuscript (preprint) (Other academic)
    Abstract [en]

    Noise is a well known challenge in hydraulic systems. Hydrostatic machines are among the largest noise contributors in a hydraulic system.The noise from the machine originates from flow pulsations at the discharge and suction ports, as well as pulsations in piston forces and bending moments.

    This article investigates the dynamic behaviour of unsteady flow through a valve plate in an axial piston pump. The proposed extension of the steady state restrictor equation includes a dynamic internal mass term and a resistance. The results from 1D model are validated with a 3D CFD model. Different valve plates’ configurations and pump sizes are easily simulated with the two simulation models. The simulation results show very good comparison with experimental tests. The proposed method is verified with a hydraulic pump application but it can probably also apply for original restrictors too.

  • 26.
    Ericson, Liselott
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems .
    Ölvander, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    En effektiv metod för att reducera flödespulsationer från variabla hydraulmaskiner2007In: Hydraulikdagar 07,2007, Linköping: Linköpings universitet , 2007Conference paper (Other academic)
    Abstract [sv]

     Den här presentationen behandlar en metod som effektivt reducerar flödespulsationer i variabla hydraulmaskiner, genom att förskjuta dödpunktens läge. Det realiseras genom att införa en fast inklinationsvinkel vinkelrätt mot den normala deplacementsvinkeln. Genom att förskjutningsvinkeln ändrar kolvarnas dödpunkt kommer förkompressionen och efterexpansionen att variera när deplacementet ändras. Tidigare arbeten visar, både teoretiskt och experimentellt, fördelarna med förskjutningsvinkeln för pumpar men inga utförligare utredningar för maskiner som arbetar både som motor och pump.

  • 27.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Flow pulsation reduction for variable displacement motors using cross-angle2007In: Power Transmission and Motion Control (PTMC 2007) / [ed] D. N. Johnston, and A. Plummer, Essex: Hadleys Ltd , 2007, p. 103-116Conference paper (Refereed)
    Abstract [en]

    This paper considers using the cross-angle in variable displacement hydraulic machines. The cross-angle is a fixed displacement angle around the axis perpendicular to the normal displacement direction. The cross-angle changes the angles to the pistons top and bottom dead centres as a function of the fraction of displacement in such a way that the valve plate timing is varied and different pre-compression and decompression angles are obtained. A non-gradient optimisation technique, the Complex method, is used together with a comprehensive simulation model in order to find the optimal cross-angle for a variable displacement hydraulic motor. The paper shows that the cross-angle can be used to reduce noise in variable displacement motors. One issue that makes the motor application more difficult is the increased dependence between outlet and inlet flow ripple which is not found in pump applications. Furthermore, the paper discusses how to use the cross-angle for machines which can work both as a motor and a pump.

  • 28.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    On optimal design of hydrostatic machines2008In: Proceedings of the 6th International Fluid Power Conference, IFK, Vol WS, 2008, p. 273-286Conference paper (Refereed)
    Abstract [en]

    Noise is a well known challenge for hydraulic systems and hydrostatic machines is one of the largest noise contributors in a hydraulic system. The noise from the machine originates from flow pulsations in the discharge and suction ports, as well as pulsations in piston forces and bending moments. To the design a quite hydraulic machine is a difficult task where many different objectives need to be considered. This paper presents a generic method for how optimization based on simulation models could be used to design quieter hydraulic machines. In order to stay competitive on a global market an efficient product development process is essential for all manufacturing industries. By using simulation-s tools in the design process, the product can be analysed before the actual product is manufactured. Furthermore, in order to find an optimal design of the machine with respect to noise, a comprehensive dynamic simulation model is needed. The model contains all important noise contributors. In the paper, the simulation models are used together with a non-gradient optimization method in order to find the best possible design. A vital part when using optimization to support design is always to formulate the objective function. As mentioned above, noise is generated from different sources and all these sources need to be considered when the objective function is formulated. For example a design that minimizes flow pulsations in the suction port will surely perform badly in some other objective. Therefore noise minimization could be looked upon as a typical multi-objective optimization problem. It is also not evident how the different objective should be ranked because the observed noise level is strongly depending on the system in which the machine is to be used. The paper also considers whether the objective function should be formulated in time or frequency domain. Traditionally, simulation of machine performance is conducted in the time domain, but the human ear hears noise in the frequency domain and perceives high and low frequencies differently. Furthermore, transformation from piston forces into emitted noise is much higher at high-frequency content than low-frequency content. This makes it natural to formulate the objective function in frequency domain, which raises the question of how the different harmonic should be ranked. In the paper a number of different approaches to formulate the objective function is presented and evaluated. The objectives considered are flow pulsation in both discharge and suction ports, as well as pulsation in piston forces and bending moments. Furthermore, the objectives are studied in both time and frequency domain. The design application is a variable hydraulic machine of bent axis type with nine pistons, which is operated both as a pump and a motor. However, the methods presented in the paper could be applied to other types of hydraulic machines as well. 

  • 29.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Johansson, Andreas
    Pump and motor division Parker Hannifin AB.
    Prediction and Optimisation of Audible Noise from Fluid Power Machines2009In: The Seventh International Conference on Fluid Power Transmission and Control, Hangzhou, Beijing: Beijing World Publishing Corporation , 2009, p. 911-918Conference paper (Refereed)
    Abstract [en]

    In this study, a transfer function methodology is employed for mapping simulated internal pump dynamics, such as piston forces and bending moments, on to audible noise. Using these transfer functions, it is possible to predict how, for instance, changed valve plate timing affects simulated piston forces and bending moments and in turn how that will affect audible noise. Hence, it is possible to design an objective function that directly reflects audible noise. The transfer functions are experimentally obtained and are valid for a specific machine shell and to some minor extent the room’s acoustical properties. Simulation of the internal pump dynamics, and optimisations, are carried out using a pump model developed in the simulation tool HOPSAN. The design application is a fixed hydraulic machine of bent axis type with seven pistons. The theory outlined and the method proposed in the paper can also be applied to other types of hydraulic machines. The paper shows how different noise reduction features affect the sound pressure level and also motor mode compared to pump mode.

  • 30.
    Krus, Petter
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, LiselottLinköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.Sethson, MagnusLinköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden2017Conference proceedings (editor) (Refereed)
    Abstract [en]

    SICFP2017

    This is the proceedings of the 15th Scandinavian International Conference on Fluid Power held at Linköping University in Sweden on 7-9 June 2017. The theme of the conference was “Fluid Power in the Digital Age”. The contributions are well aligned with this theme, and are indeed reflecting the great developments. We are very grateful to the effort put in by the authors to produce such high quality papers, and also to those taking time to review papers to further enhance the quality. The contributions clearly shows that the fluid power industry, and academia, have both challenges as well as opportunities in keeping up with the evolving capabilities provided by the digitalization. It was with great joy to see old and new colleagues and friends attending our conference and the division of Fluid and mechatronic systems, at Linköping University. The conference is a bi-annual event, with alternating localization between Linköping in Sweden and Tampere in Finland. The process of hosting such an event is a great effort for our organization and I would like to thank all those involved in organizing this conference, and wish good luck with the next one to our Finnish colleagues. Thank you!

    Prof. Petter Krus

    Head of Division

    Fluid and Mechatronic Systems

    Review Process

    Each author attending the conference days had the opportunity to select from three different ways of presenting their contribution. Firstly, a reviewed process with at least two international reviewers of each contribution. The process resulted in most cases with feedback from the reviewers with comments spanning everything between diagram legends to scientific methods. Some proposed papers where rejected upon recommendations from reviewers. Secondly contributions where also presented in industry sessions where the review process where internal only by the staff of the division. A third extended abstract presentation format where also presented during the conference.

    This proceedings contain all presented contributions from the reviewed papers in the first section and thereafter the non-reviewed papers in second section. All reviewed papers are marked in the footer by the acceptance date.

  • 31.
    Krus, Petter
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Sethson, MagnusLinköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.Ericson, LiselottLinköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    13th Scandinavian International Conference on Fluid Power, June 3-5, 2013, Linköping, Sweden2013Conference proceedings (editor) (Refereed)
1 - 31 of 31
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