Water hydraulics is a growing technology area mainly due to environmental, safety and cleanness reasons. Water hydraulic systems have proved to be the best technology alternative in some industrial sectors such as food, processing, paper, steel and power industry. The main challenges for water hydraulics technology are proper design, good reliability and controllability at a reasonable price level. When these requirements are fulfilled, water hydraulic systems should be fully competitive to other systems.
The objective of water hydraulics motion control research is to improve the controllability of the systems. This paper considers the current possibilities and challenges in water hydraulics motion control. Component technology is shortly discussed, including control valves and actuators. After the component technology, the present control methods in water hydraulics motion control are explained. The challenges in position, velocity and force control are exemplary described. Finally, two examples of new water hydraulic motion control systems are presented: Example 1. Positioning system with on/off valves, Example2. Cavitation free proportional pressure relief valve for water systems.

抄録全体を表示

In the paper the development of the servo pneumatic control systems, including the structures of the servo valves, the analysis and design of the controller for the pressure and the position control systems and which applications are introduced. The different control methods for the nonlinear pneumatic servo systems are implemented in the microcomputer to control. And, the digital controllers PID, fuzzy and neural fuzzy, self tuning neural fuzzy, adaptive controller are also progressed and applied in the pneumatic servo control system. In the paper, a high precision control of the pneumatic cylinder controller with the velocity compensation is also reported.

抄録全体を表示

This paper features the development of a double-effect deformable actuator, conceived as the synthesis of a fluid muscle actuator and a pneumatic spring. The actuator is therefore able to exert both compression and tension forces. The paper describes the scheme of the actuator and the design solution adopted. Subsequently the results of experimental tests for the static characterisation are presented. The results show the compression and tension force of the actuator as a function of supply pressure and stroke. These experimental characteristics are evaluated, discussed and compared with the theoretical results provided by an analytical model. Finally, some possibilities for application and further development of the actuator are proposed.

抄録全体を表示

This paper presents a novel approach of driving the human joints by means of the fluid control system with flexibility just like the clothes, which leads to realize the cyborg amplifying the human motor function. The former proposed actuators on the assumption of the body mounting were not always designed from the point of the clothing comfort. Then, in the first part of this paper, the index of clothing comfort is introduced so as to evaluate the desirability of the actuator mounted on the body. Second, tube actuators by pneumatics with the novel structure are systematically proposed to increase the introduced index. And third, by using them, the efficient driving method of both the arm and the leg is shown to realize “Wearable Fluid Power” so as to assist the disabled on their walk or to improve their sport skill.

抄録全体を表示

The pneumatic muscle actuator (PM) with axial threads is a different idea from the McKibben PM. The muscle consists of an elastic bladder, similar to a tube, that is attached at either end to fittings. Inside the bladder longitudinal high resistance cables are inserted. Outside some circular rings stop the radial deformation in some points. When the internal bladder is pressurised the actuator shortens. The high power to weight ratio and the compliance of these actuators are attractive for many applications such as prosthetic and orthesis appliances. The working modality of these actuators is repeated contractions and extensions of the muscle. This repeated action is a heavy load for these actuators and leads to failure. The life span of the PM is often shorter than others actuators, such as pneumatic cylinders and electric drives. In this paper a model to predict the life of the PM is presented. Experimental results are carried out to validate the model and show the strong influence of the material used for the bladder. The silicone rubber shows a life of hundreds cycles at full contraction, while it reaches ten thousands cycles at partial contraction.

抄録全体を表示

A robot able to climb poles was built. The robot consists of a pneumatic flexible actuator as the body with the upper and lower heads supporting the devices that catch the pole. Passive, no actuated, pole locking was provided. The robot kinematics was inch-worm inspired. A complete gait consists of stretching and restoring sequence of the body length. In the stretching phase the lower locking device can stick to the pole whereas the upper locking device can move up freely. In the restoring phase the locking devices work switched. A numerical model of the robot dynamics was developed as well. The inputs for the model were obtained by experimental data. In doing that, a full experimental characterisation of the robot was carried out.

抄録全体を表示

The purpose of this study is to develop a gentle human like robot hand. We designed a pneumatic rubber hand which has four fingers made of silicon rubber and called soft grippers. The soft gripper has a chamber which is reinforced with fi ber in a circular direction and a thin plastic sheet in the lower part of the gripper. The soft gripper has a displacement sensor based on a flexible strain sensor that we have developed earlier. The flexible sensor is made of electro-conductive paint and silicon rubber. We have developed a pneumatic rubber hand for enveloping grasp and finger-tip grasp. In this study, we improve the hand to grasp an object stably. Further, we construct a control system for grasping an object surely and gently.

抄録全体を表示

This paper presents a new fuzzy PID algorithm of asymmetric fuzzy strategy for pneumatic robot position control. It can effectively solve the difficult problems of single rod cylinder, which are mainly caused by asymmetric structure and different friction characteristics in two directions. Both the theoretical analysis and experimental results prove that, with this strategy, the dynamic performance of the system can be much improved. The system obtains desired percentage overshoot and repeatability in both transient and steady-state responses.

抄録全体を表示

When robots work together with a human or contact with a human body directly in such as a medical welfare åeld, in order to avoid an accident from crash and so on, a çexibility is required for the robot.
The purpose of this study is to realize a safe mechanism for a human-friendly robot. The soft mechanism comprises a soft actuator and a soft sensor. The soft actuator and soft sensor are made of a silicone rubber body and driven with a pneumatic power.
In this paper, the structure and the fundamental characteristics of soft actuator and soft sensor are described, and then the structure and the fundamental operation of the developed soft hand are shown.

抄録全体を表示

IS06358 was published in 1989 as a standard which specifies the determination of flow-rate characteristics for pneumatic components. Then, in Japan, JIS B 8390 corresponded to IS06358 was published in 2000. These standards represent the fl ow-rate characteristics over the full range using “Sonic conductance C” and “Critical pressure ratio b.” In this paper, comparison with IS06358 and Existing representation method. Moreover, the problemof the measuring method by ISO was clarified and the flow-rate characteristic model for the representation method was proposed. Furthermore, the method by “Effective conductance” which grasps the flow-rate characteristic of pneumatic components with a single parameter was suggested, and the development of the test method replaced with the ISO method was suggested.

抄録全体を表示

The test method for the flow characteristics of a pneumatic solenoid valve is specified in ISO 6355. In this standard, the fl ow characteristics are shown by the sonic conductance and the critical pressure ratio, and these are calculated from the fl ow rate, the pressure and the temperature of the air that passes the solenoid valve. When the flow characteristics of a large solenoid valve are measured by this method, a large compressor and a large flow meter are required. Therefore the power consumption and the generating noise become very large. In this study, a test method using the small and low noise test equipment is developed. In this method, at first the tank connecting to the solenoid valve is evacuated, and then the air is charged in the tank through the solenoid valve from the atmosphere. By using the pressure and temperature in this tank, the sonic conductance and the critical pressure ratio are evaluated.

抄録全体を表示

By measuring the variation of differential pressure between a master tank (without leakage) and a measured tank (with leakage), leakage flow rate of the measured tank can be calculated.
In this research a new calculation method is studied for measuring air leakage flow rate. Based on the law of air flow through a leakage hole, the theoretical formula of the leakage flow rate which has unacquainted parameters is got. By using statistics method, the unacquainted parameters in the mathematic model of the differential pressure, namely the unacquainted parameters in the theoretically formula of leakage flow can be estimated by differential pressure from experiment. Thereby leakage flow can be calculated and the error of leakage flow can also be determined. Compared with mass flow meter as standard measurement, the accuracy of leakage flow rate by the new method is higher than by the traditional method.

抄録全体を表示

There are many kinds of method for flow rate measurement nowadays. And orifice flow meter is a most popular instrument of flow rate measurement in industry. But a value of measurement flow rate is in proportion to the square root of pressure difference. So this flow meter has narrow range-ability. And it is very difficult to get high accuracy in range of lower flow rate.
The research about the flow meter in which the orifice area is a function of the differential pressure is reported in 1972 [1]. According to this study, the range-ability of flow meter has been improved over a range of 100: 1. But it has not been confirmed in detail the flow rate characteristics by experiments.
In this time, we confirmed the flow rate characteristics of this flow meter experimentally. And we studied about the flow rate coefficient and the influence of fluid power upon its flow meter. In addition, we tried to clarify the principle of measurement about this flow meter.

抄録全体を表示

In this paper, alternative methods for obtaining the sonic conductance and the critical pressure ratio are presented. The methods use the isothermal chamber that can almost realize isothermal condition due to larger heat transfer area and heat transfer coefficient by stuffing metal wire in it. Using this chamber, the sonic conductance and the critical pressure ratio are obtained by measuring only pressure in the chamber. With this method, it takes only some seconds and costs lower energy than the ISO 6358 procedure. Furthermore, the authors haveinvestigated the effect of temperature change in the isothermal chamber. In the proposed charge method, temperature change affects pneumatic characteristics measurement not so much. On the other hand, the proposed discharge method is easy to be influenced by temperature change. However, the discharge method has the merits not to dependon the dynamic characteristics of the regulator and to simplify the measurement system.

抄録全体を表示

An optical servo system is a new control system that can be used in hazardous environments. The purpose of our study is to develop such an optical control system. In a previous study, we had realized an optical control system that executed cart positioning using optical control signals instead of electric signals. We developed an optical servo valve in which the output pressure was proportional to input optical power. As a next step, we needed to develop another type of optical valve in order to get higher-pressure gain. In this study, we propose and produce an optical on-off valve that consists of an optical on-off device and a fluid amplifier, and the structure, operating principle and fundamental characteristics of the valve are investigated. As the result, we obtained a higher output pressure of the tested valve compared with the previous one. And we proposed the analytical model of the optical on-off device and identified the system parameters. We confirmed their validity by comparing them with experimental results. And finally, we improved the dynamics of the device by using a feedback passage plate based on analytical results of the device.

抄録全体を表示

An opto-pneumatic servo system employing opto-fluidic converter and pneumatic valve can operate the mechanical system directed by optical signal and work in hazardous environments because it does not use the electric immediate signal. The converter transforms the optical signal intensity into proportional fluid power, i.e. pneumatic pressure, although the pressure is stillweak and is not enough to operate the mechanical system directly. In this report, as the practical system, the opto-pneumatic servo valve is developed.
The output pressure of Opto-fluidic converter is enlarged proportionally in the serial stages of fluidic amplifier and led to pneumatical input of servo valve as a pilot signal which excite the both sides of spool in the valve. The study is mainly carried out for optimizing the design of serial stage of fluidic amplifier, in order to generates the enough high output pressure which can be used as the pilot (operate) pressure in the pneumatic proportional valve. The performances and applications of thesystem will be shown.

抄録全体を表示

There is a growing awareness of the need to foster international links and various initiatives have been taken. Within Europe eight major academic research centres have formed the Network of Fluid Power Centres in Europe (FPCE) and other workers have formed the Fluid Power Net International (FPN) to encourage collaboration and dissemination of knowledge. These developments have taken place against a background of an increased number of national and international conferences and meetings concerned with fluid power research and its applications.
The paper provides a background to some of these developments and examines the opportunities that they provide for improving International Collaboration.

抄録全体を表示

The paper deals with engineering education having the focus on research skills as well as experimental based project organised didactic self-learning within the area of design of mechatronic products and systems, in particular intelligent fluid power components and systems. Experiences with interactive methods for improving of MSc-and PhD-students' research and self-learning competence at the Technical University of Denmark and the Aalborg University are presented and discussed. The didactic approach has two legs:(1) Analysis and IT-modelling of products and systems from day one at the university, and (2) Synthesis with increasing project activities focusing on product development and design engineering, including testing, evaluation and validation. The objective is to educate candidates with highlevel professional engineering skills for research and integrated product development teams working within mechatronics and fluid power in order to make successful business in companies as well as at universities. Most of the projects are in cooperation with companies.

抄録全体を表示

A hydraulic free piston engine (HFPE) combines a diesel engine and a hydraulic pump into one compact component. The piston assembly motion is influenced by pressures and inertia forces only and no mechanical linkage control the motion. The piston assembly moves during operation linearly back and forth between dead centres by means of the fuel energy producing directly hydraulic energy. HFPE do not allow or it is not sensible just to replace the traditional crankshaft engine-pump combination. In the worst case the whole hydraulic system must be redesigned. The features that harm HFPE use are: Reliable compression ratio control requires steady load pressure; The pump displacement is fixed or stepwise variable; High piston accelerations at dead centres cause need of supply pressure i.e. closed hydraulic system. However, the problems can be overcome and some solutions exist. The paper introduces and compares mentioned solutions. The comparison criteria are efficiency, controllability, usability and costs.

抄録全体を表示

To conduct the reliability test or functional life test for hydraulic components usually takes more time than one can predict and consumes more resource than one can image, especially for those with higher reliability and simpler components. This paper is presented to discuss the theory and method of accelerated testing, which has been widely used in electronics field, and to discuss the factors that affect the functional life of hydraulic components as well as the failure mode. The advantage and disadvantage of accelerating testing will be discussed. The author also intends to point out the importance of failure definition and accelerating model in the accelerated tests. Several accelerating models such as Arrhenius model and Inverse Power model will be discussed. The degradation process of metering edge is taken as the research subject to propose the applicable accelerating model. The possibility of using contaminated hydraulic fluid as an accelerating factor is discussed.

抄録全体を表示

Pneumatic positioning actuators are commonly used to control process control valves in petroleum, chemical, and paper industries. Pneumatics has many advantages in these applications, but there are also drawbacks. The purpose of this study is to find out if low-pressure water hydraulics can be used in the control applications of process valves. Low-pressure water is available in some process industrial applications. However, water hydraulics is considered very expensive technology. Some feasibility studies claim, though, that low-pressure water hydraulics is relatively cost effective. In this paper advantages and drawbacks of pneumatic and low-pressure water hydraulic solutions are discussed. Design, modeling, simulation, and experimental results of the low-pressure water hydraulic control of a process valve are presented. The performance requirements of a low-pressure water hydraulic servo valve are studied in simulations and experimental tests. Evaluation of the feasibility of water hydraulics in positioning applications of process valves is discussed.

抄録全体を表示

Oil Hydraulic systems are employed in a wide range of engineering fields because of their rapid response and high power density. However, increasing public awareness of environmental issues call for environmentally friendly pressure medium like water to prevent environmental damage caused by potentially harmful material leakage from oil hydraulic system.
In this study, a water hydraulic high speed solenoid valve with two stage mechanism and no inner leakage is developed. The particular feature of this valve is the utilization of the leakage from the clearance between main poppet and sleeve as inner pilot flow. The experimental results using the prototype valve show excellent response characteristics and that proposed valve is valid for the control of water hydraulic systems. It is also discussed to improve the performance of this valve by the alteration of the design parameters.

抄録全体を表示

In recent years the water has been paid attention as a working fluid again, for the demand of the technology considering the global environmental problems. In this paper we compose the water hydraulic servo system by combining a servo valve and a hydraulic motor and we study the control performance of rotational angle. The problem in the system is the existence of unmodeled dynamics, e.g. large starting torque and friction force of water hydraulic servomotor, which cause the significant performance degradation. We composed the gain scheduled PID -controller that improves the large steady state error and overshoot. We are succeeding fairly in attenuating the steady state error of water hydraulic servomotor.

抄録全体を表示

Shape memory alloys have many unique properties. These alloys can be plastically deformed with moderate forces at low temperature, and upon exposure to some higher temperature the alloys will return to its original shape prior to the deformation with more than decade higher force. The power density of shape memory alloys is high and the inactivity in harsh environments makes them enticing choice for valve actuators. Still the shape memory alloy has one disadvantage that makes valve actuator appliances hard to find. The transformation between different states of shape memory alloy is proportional to the energy supplied when the alloy is heated but the cooling is only proportional to the heat transfer ratio between the alloy and environment. Using pair of thin shape memory alloy fibers replacing a torque motor of a traditional nozzle flapper servovalve has been studied. The studied flapper actuator consists of two SMA-fibers arranged in antagonist fashion. When one fiber serves as an actuator the other one serves as a spring. Both fibers are immersed in water in order to increase heat transfer rate. The performance of developed shape memory fiber actuator has been simulated. Simulations have been verified by comparing simulation results to experimental tests. Based on experimental tests of actuator the performance of shape memory fiber actuated nozzle flapper pilot stage has been simulated with verified valve model. The attained overall performance of a 2-stage 4-way spool valve with the developed pilot stage has been discussed.

抄録全体を表示

The paper studies the possibility to replace expensive water hydraulic proportional valve with a number of low-cost on/off valves. A position control system of a water hydraulic cylinder is realized with eight two-way solenoid valves and one four-way on/off valve. A pulse code modulation is used to achieve almost proportional control. A position controller based on multi-rate sampling is developed to minimize position error. Experimental results with a high inertial load show smooth movements, 0.2mm position accuracy and 200mm/s maximum velocity. The advantages and disadvantages of the on/off valve system are discussed.

抄録全体を表示

Low-pressure water hydraulics is an attractive technology having the low price of pneumatics, good controllability and stiffness of oil hydraulics as well as safety environment. This paper deals with the dynamic characteristics of the low-pressure water hydraulic system consisting of a vortex pump, a fl exible tube with a length of 10 m, an electro-magnetic on-off valve and a single rod cylinder with some inertia loads. The step responses on the pressure and the piston displacement in the water hydraulic system under the operational conditions of a low pressure are obtained experimentally. The computer simulation of the system under the above conditions was done by using the simulation software of OHC-Sim developed by our research group. The efficiency in the system is also discussed on the basis of the system simulation.

抄録全体を表示

Two simple velocity control systems of a water hydraulic motor are experimentally compared in this study; one with commercial pressure compensated proportional flow control valve and another with parallel-connected low-cost on/off solenoid valves. The aim of the study is to define suitability of these control techniques in a system where good velocity control accuracy is a significant requirement.

抄録全体を表示

Filtration in water hydraulic systems may be very problematic, due to physical and biological contamination. This contamination may cause quick increase in the pressure difference over the filter element thus, the aim of this research was to test depth type filter and determine the effects of microbial growth and particulate contamination on filtration in a water hydraulic system. In this paper the results of these experiments are presented.
Experiments were made with a pilot-scale water hydraulic system, which induces no biological contamination and only a minimum amount of particulate contamination. Filtered tap water was used as a pressure medium. Tested depth type filter element had a filter rating (β>5000) of 10μm. Test periods were three weeks. Pressure difference over the filter, ffiluid fiow and temperature were monitored. Microbial analyses consisted of determinations of the total number of cells, heterotrophic viable plate counts and concentration of dissolved organic carbon.
Slight microbial or particulate contamination is not a serious problem considering the lifetime of the filter element. When microbial and particulate contamination occured at the same time, the situation became much more complicated. In this situation microbial growth prevented the normal operation of depth type filter element.

抄録全体を表示

This paper deals with characteristics of hydrostatic bearings, which is used in water hydraulic valves for supporting a valve spool to avoid wear and sticking of the spool to the sleeve. The hydrostatic bearings should have a sufficient spring constant for the supporting, while minimizing the leakage flow through the clearance between the spool and the sleeve. To satisfy these requirements, a strict combination of dimensions of the hydrostatic bearings and the clearance is required. Using a newly designed experimental rig, pressure distribution in the clearance and leakage through the clearance for various eccentricities are measured and compared with a computer simulation. The experimental value of supporting force is calculated integrating the measured pressure. The result of this study will be used to improve accuracy of the designing.

抄録全体を表示

This paper studies velocity control of a low-pressure water hydraulic cylinder drive. Two different systems are used, one with a proportional 4/3-way directional control valve and one with a proportional flow control valve. Experimental results with the proportional directional valve show that good control results can be achieved with closed-loop control system. Compensation of system nonlinearities allows also open-loop velocity control, which gives quite good accuracy in constant conditions. However external load force increases the velocity error and when good accuracy is needed in varying load conditions, the closed-loop control system has to be used. The results with the flow control valve are not as good but on the other hand the price of the valve is lower, which supports the use of this valve if the accuracy demand is not so high.

抄録全体を表示

A compact and lightweight water hydraulic motor has been developed with the aim of applying to water hydraulic systems that utilize tap water as the transfer medium of energy. The developed water hydraulic motor, which drives in the low-pressure range equal or less than 2.0MPa, has power equivalent to 100W. Structurally based on a balanced vane type motor, it has achieved high efficiency and durability through structural improvements, use of most suitable materials selected in order to minimize energy losses.

抄録全体を表示

In this paper, the static force/stroke characteristic of switching solenoid is linearized by using the traditional PIcontroller as well as the fuzzy-logic-controller. The major aim is to develop a proportional switching solenoid having the advantage of lower cost as compared with a usual proportional solenoid. Besides, two different methods to implement the linearization are adopted. One is the employment of a force sensor to generate the actual feedback force signal, and the other is the utilization of the numerically estimated pseudo-force as the feedback signal. Experimental results prove that the nonlinear fuzzy-logic-controller is superior to the conventional linear PI-controller concerning the compensation of the high nonlinearity near the end-position of the plunger.

抄録全体を表示

It is generally not easy to acquire high positioning accuracy in hydraulic servocontrol systems, since they have an intense non-linearity, such as dead zone, which is originally caused by the leakage and friction. It is considered that the Neural Network compensator is one of the available options to get over the inherent problem. This paper deals with the eect of dither/PWM signals on the steady position error in the hydraulic motor drive system with a state feedback Neural Network. From the computer simulation, it is clarified that the application of the dither/PWM signals to the Neural Network control system improves the positioning performance by accompanying the assistance of the Neural Network capability. In addition, the effectiveness of the dither/PWM signals is also verified by experimental results.

抄録全体を表示

This paper examines an application of Neural Network for identification and control of a servovalve controlled hydraulic cylinder system. The linearized transfer function of a nonlinear plant is determined by applying a selfexcited oscillation. Neural Network is utilized on-line in mapping the inherent nonlinearities as well as in adaptive identification of system parameters. Neural Network controllers having variable proportional gain together with velocity feedback gain characteristics have been employed. The effectiveness of the Neural Network is confirmed through computer simulations and experiments.

抄録全体を表示

The Stewart platform is one example of a parallel manipulator with high force to weight ratio and fine positioning accuracy far exceeding those of a conventional serial-link arm. It is basically a closed-link type robot manipulator having 6 degrees of freedom. In this paper the implementation of an adaptive control scheme based on fuzzy logic theory is used to control the motion of a Stewart platform manipulator. The inverse kinematics is analysed and six individual controllers are implemented in the actuators coordinates. An experimental study is conducted to evaluate the performance of the proposed control scheme implemented to control the manipulator to track a defined path. Experimental results show that the proposed control policy provides superior tracking capability as compared to the fi xed-gain controllers.

抄録全体を表示

The design of individual lubricating gaps with their bearing and sealing function mainly determines the loss behaviour, life time, reliability and achievable technical parameters of displacement machines. The gap flow conditions are influenced by the operating parameters, the gap macro geometry, the surface quality and by the chosen surface material. Therefore the determination of the time dependent gap height requires very complex simulation models considering the motion of moveable parts, the interaction between machine parts, the dependency on design and operating parameters and the energy dissipation within the gaps as well as changes of the gap height caused by the flexibility of the applied surface material. This paper introduces a new method for complex gap flow simulation of connected and self-adjusting gaps of axial piston machines, where the model for the piston/cylinder pair was extended to consider elastohydrodynamic effects. The simulation model has been verified with the help of friction force measurements on the piston/cylinder assembly.

抄録全体を表示

The mixed lubrication characteristics of hydrostatic thrust pad bearings under eccentrically and dynamically loaded conditions are studied theoretically. On the basis of the operation of hydraulic pumps and motors, the eccentricity of loads, time-lag of changes in between the supply pressure and loads, surface roughness, recess volume and the bulk modulus of liquids are examined. The basic equations applying the perturbation method are developed; the three dimensional motion of the bearing is simulated; and the solutions including the pressure distributions, friction, flow rate, power loss and the stiffness are obtained. The calculations indicate that: The eccentric load causes local contacts. The preceding change in loads poses the larger motion of the pad. As the recess volume increases or the bulk modulus decreases, the bearing stiffness decreases.

抄録全体を表示

The purpose of this study is to explain the loss mechanism between piston shoe and swash plate of axial piston units and to derive new presuppositions for developing a new unit or improving an existing one. The film thickness was measured at constant pressure to find out the correlation between speed and the drag flow effect. The behavior of the film thickness between piston shoe and swash plate in the real unit was described through combining a squeeze-film-effect with a drag flow effect.

抄録全体を表示

It is difficult, if not impossible, to select any single test that will model the expected performance of hydraulic fluids in a wide range of hydraulic pumps. Increased pressures often encountered in new hydraulic pump applications compounds this problem. However, some basic assessment of hydraulic fluid performance is necessary for numerous reasons such as: developing an appropriate fluid purchase policy, international standard development, fluid classification and others. Since the classic standard tests such as: ASTM D2882, DIN 51389 and others are simply inadequate for this task and also since the manufacturer, Eaton Inc., no longer manufactures these pumps, it has been necessary to develop an alternative test [1-3]. The Bosch-Rexroth Corporation has developed a high-pressure piston pump test that has been an excellent predictor of hydraulic fuid performance for many years. This test is currently being developed as a candidate for an ASTM Standard and is the subject of this report.

抄録全体を表示

The present paper details advances attained in the modelling and simulation of axial piston pumps. The simulation environment is AMESim and new in-house developed submodels allow a quantitative appraisal of exchanged forces inside the pump. Care is devoted to the analysis and modelling of the port plate geometry that significantly contributes to the fl ow ripple. An advantage of the proposed simulation approach lies in the fact that pump geometry features are accounted “parametrically”, this contributing flexibility while assessing and comparing performance of different pump designs. Experimental studies are also presented and critical analysis of results while serving the purpose of validating specific aspects of predictive simulations also allow to stress the limits involved in the modelling phase.

抄録全体を表示

This paper overviews a direct method to evaluate the pressure distribution and the leakage across the clearance gap between a piston and cylinder block and similarly for the clearance between the associated slipper and swash plate. The method, based on the well-known Couette-Poiseulle and Reynolds equations for laminar flow, takes into account the reality of many piston/slipper designs. The new set of equations are used to consider the nature of the leakage flow for a piston with five grooves, and for a slipper with one groove, and within a 9-piston pump. It is shown that the total leakage flow has a very small-amplitude oscillation due to combined piston leakages, but is dominated by the combined slipper leakages. Predictions are compared with measurements for the pump operating with a 5/95 emulsion, and the comparison is shown to be extremely good. The predictions are shown to be superior to the case had the groove effects been neglected.

抄録全体を表示

Extended Kalman Filter (EKF) is used to estimate friction and spring characteristics on the swash plate of a variable displacement pump. In earlier studies, the feasibility of the approach was established using simulation studies to establish limits of accuracy for the EKF approach when applied to an ideal situation. In this study, the EKF is applied to an experimental system and the issue of reliability in estimation of certain pump parameters is addressed. In addition, an approach to assign values to accommodate convergence of the EKF is considered. A special experimental system was set up to facilitate the measurement of certain states to enhance the EKF approach. Estimated parameters did show some scatter about a specified operating point but in general, were reasonably repeatable. Good control over operating conditions was absolutely essential for repeatability. The study also showed that changes in the system parameters could be accurately tracked.

抄録全体を表示

Numerous combinations of the design parameters usually exist when a machine is designed by simulation. It is very difficult to make a search for the optimum combination when a designer combines the parameters by himself because the search is very much likely to be biased and manipulated.
We have developed a simulation program predicting the internal state of a vane pump. In this study, we have attempted to design the vane pump with small pressure fluctuation by using a simulation program that combines the genetic algorithm that is one of the optimum-value search algorithms with the program. The design parameters to be varied by the genetic algorithm were the shape of the cam ring in a vane pump.
In this paper, effectiveness of the genetic algorithm for a pump design is reported to have been verified by experiments using the cam ring based on the simulation.

抄録全体を表示

There is currently underway a project, which is being conducted by the ASTM D.02N.07 Piston Pump Task Force, to develop a standard high-pressure piston pump test and related pump testing protocol. Various pump tests are being considered including proposals submitted by Komatsu, Rexroth, Denison, Vickers and others. The objective of this paper is to provide an overview of the importance and current status of this work and to outline future directions this work is likely to take.

抄録全体を表示