Plate Type Axial Piston Pump Research Articles

Evaluation of Slipper Behavior Considering the Deformation of Retainer of Swash Plate Type Axial Piston Pump

Evaluation of Slipper Behavior Considering the Deformation of Retainer of Swash Plate Type Axial Piston Pump

Study on the Solid-liquid Interaction Characteristics of the Oil Film within Piston Cylinder Pair of the Ultra-high Pressure Swash Plate Type Axial Piston Pump

Study on the Solid-liquid Interaction Characteristics of the Oil Film within Piston Cylinder Pair of the Ultra-high Pressure Swash Plate Type Axial Piston Pump

A Novel Approach of Studying the Fluid–Structure–Thermal Interaction of the Piston–Cylinder Interface of Axial Piston Pumps

The friction in the swash plate type axial piston pumps is mainly influenced by the fluid film in the friction interface. The piston–cylinder interface is one of the key friction interfaces in the pumps. The film geometry is determined by the gap between the piston and the cylinder. The dimensions of the parts determine the gap geometry, and the deformation of the structure also influences the gap geometry. The fluid viscosity is strongly influenced by temperature. Thus, a novel approach of studying the fluid film, the structure, and temperature interaction is provided in this paper. A full and quick fluid–structure–thermal interaction simulation is realized. Then, a dynamic model of the piston–cylinder interface, which integrated the fluid–structure–thermal interacting effects, has been developed. Finally, an approach for calculating the extra friction force between the piston and the cylinder is provided. Compared with the measurement data, the simulation results of the axial friction force achieve a good fit. The present work allows a fast prediction and detailed support for designing the piston–cylinder interfaces.

Pressure compensator design, simulation and performance evaluation of a variable displacement swash plate type axial piston pump

This work presents a simple design procedure of a pressure compensator of a swash plate type variable displacement axial piston pump (VDAPP). The route of the work mainly focuses on static design through balancing the torque given by the pump pistons, rate cylinder and strok- ing cylinder on the swash plate during cut-in (maximum flow) and cut-off (minimum flow) pressure condition of the system with an objective of minimizing the output pressure ripples. The outcome in terms of pressure from the dynamic simulation of the designed compensator with pump has been compare with experimental result obtained from a reference commercial pump has compensator with duel spool. The model has been used for performance prediction for wide variations of the load valve area settings.

Virtual Assessment and Experimental Validation of Power Loss Contributions in Swash Plate Type Axial Piston Pumps

The understanding of the power loss contributions of each loss source is essential for an effective development of swash plate type axial piston pump. However, it is difficult to obtain the assessment of the power loss distribution due to the lack of methodologies that allow an independent evaluation of each source. This paper addresses this challenge using the most recent simulation methods. It describes the determination of each source, along with the corresponding loss of performance, and the principle of their prediction during the design phase. It also reports the validation of the simulation model by comparing the simulated dynamic displacement chamber pressure and the solid body temperature distribution with measurements obtained from a special pump prototype. This proposed virtual assessment of power loss contributions is demonstrated on a commercial hydraulic unit and the detailed results are reported in this paper.

Active Vibration Control of Swash Plate-Type Axial Piston Machines with Two-Weight Notch Least Mean Square/Filtered-x Least Mean Square (LMS/FxLMS) Filters

In this paper, swash plate active vibration control techniques were investigated utilizing the weight-limited multi-frequency two-weight notch Least Mean Square (LMS) filter with unit delay compensation and multi-frequency two-weight notch Filtered-x Least Mean Sqaure (FxLMS) filter with offline modeling to achieve adjustable swash plate vibration reduction at the desired frequency. Simulation studies of the high fidelity pump control system model including realistic swash plate moments are presented to demonstrate the feasibility of the swash plate active vibration control. A 75-cm3/rev swash plate type axial piston pump was modified to implement a high bandwidth pump control system which is required for canceling the swash plate vibration. High speed real-time controllers were proposed and realized using an National Instrument LabVIEW Field Programmable Gate Array (FPGA). Vibration measurements using a tri-axial swash plate acceleration sensor were conducted to show the influence and effectiveness of the proposed swash plate active vibration control system and algorithms.

양방향 구동 사판식 액시얼 피스톤 펌프의 밸브 플레이트 노치 설계에 관한 연구

양방향 구동 사판식 액시얼 피스톤 펌프의 밸브 플레이트 노치 설계에 관한 연구

Constant pressure control of a swash plate type axial piston pump by varying both volumetric displacement and shaft speed

In this paper both the volumetric displacement and the shaft speed of a variable displacement swash-plate type piston pump were varied in order to minimize power consumption in supplying constant-pressure oil to a valve-controlled hydraulic cylinder, particularly during idle modes. At operating modes which were launched by position command inputs, the pump speed was varied by a pressure control algorithm to maintain a constant system pressure, with the swash plate angle fixed at the maximum. At idle, with no position controller input signal and the system pressure greater than or equal to the reference value, the swash plate angle and pump speed were lowered to their minimum limits. Computer simulation and experimental results showed that the idling power could be reduced by up to 83% by reducing the pump speed from 1800 rpm to 300 rpm and the swash plate angle to 3°, compared to a conventional system consisting of a pressure-compensated variable displacement type pump driven at a constant speed of 1800 rpm.

Investigation of the power losses from hydrostatic piston shoe bearings for swash plate type axial piston pumps under mixed friction conditions

Swash plate type piston pumps, when applied to electro-hydrostatic actuators, operate mostly in the mixed lubrication speed range, compensating for position control errors of actuator parts. Therefore, their hydrostatic piston shoe bearings should be designed to minimize frictional and leakage losses as well as the wear rate, which could be increased by insufficient hydrodynamic lubrication in the low speed range. In this study the influence of the balance and recess ratios of piston shoe bearings on their power losses were investigated under mixed friction conditions. The fundamental properties of piston shoe bearings tilted on a swash plate, such as the lift force, righting moment and leakage flow rate, were computed using a simplified Navier-Stoke’s equation, to obtain an insight into methods of minimizing the power losses of piston shoes exposed to mixed friction. Six test models were designed with these two parameters decoupled and tested on apparatus which was developed to measure the friction force and leakage flow rate of a piston shoe in the motor speed range below 100 rpm. The tilting motion of the piston shoes could be observed in the mixed friction speed range and power losses could be reduced by increasing their resistance to external tilting moments.

사판식 유압 피스톤 펌프의 슬리퍼 정압베어링면 형상에 관한 이론해석

In the high rotational speed and pressure state, the leakage flow rate of the axial piston pump is one of the serious problems and make great reasons to decrease the volume efficiency. In this study, tribology characteristics is clarified for the hydrostatic slipper bearing in the swash plate type axial piston pump, by means of theoretical analysis for the different shape of the hydrostatic slipper bearing. It was analyzed by Mathcad software and used equal conditions at swash plate angle in each model. The results show that performance characteristics of the swash plate type axial piston pump are significantly influenced by the shape of the hydrostatic slipper bearing.

Numerical Simulation of a Slipper Model for Swash Plate Type Axial Piston Pumps and Motors: Effects of Concave and Convex Surface Geometry

In this study, the slipper of swash plate axial piston pumps and motors is modeled as a hybrid (hydrostatic and hydrodynamic) thrust pad bearing. The effects of the slightly concave and convex geometries of the slipper sliding surface are examined. The motion of the slipper model is numerically simulated, and its tribological characteristics are examined under eccentric and dynamic load conditions. The calculations under these conditions indicate that, for the concave slipper, the fluctuation of the bearing pad azimuth increases, and the attitude of the slipper becomes unstable. In contrast, for the convex slipper, the attitude becomes stable, but the clearance increases.

사판식 가변 용량형 액셜 피스톤 펌프의 일정출력 레귤레이터 특성 시뮬레이션

In this study, modeling and numerical simulations has been performed to investigate performance characteristics of constant power regulator system for swash plate type axial piston pump. The commercial numerical simulation software, AMESim was applied for analyzing the dynamic behavior of constant power regulator system of swash plate axial piston pump. The validity of simulation model of constant power regulator system is verified by comparing simulation results with experiments. Also, the behavior of main components of constant power regulator system such as spool, sleeve and counterbalance piston is investigated using the results of computer simulation.

Simultaneous temperature measurements of bearing and seal parts of a swash plate type axial piston pump — effects of piston clearance and fluid property

Temperatures of three bearing and seal parts of a swash plate type axial piston pump were measured simultaneously using a slip ring with thermocouples’ amplifiers. The rotating cylinder block had five thermocouples, the swash-plate had four, and the valve-plate had four. Three sets of pistons with different diameters were prepared. Hydraulic mineral oil with VG22 and a water-glycol type hydraulic oil with VG32 were used as test fluids. The maximum discharge pressure was 20 MPa; the maximum rotational speed was 25 rps. The inlet oil temperature was 20–40°C. Temperatures and temperature differences between the bottom-dead-center and the top-dead-center increased concomitantly with the discharge pressure. For larger piston clearance ratios, the temperatures rose monotonically. The bearing and seal parts were markedly hotter than the discharge oil. Temperatures rose much less using the water-glycol type oil than when using the mineral oil.

B30 斜板式アキシアルピストンポンプ・モータのスリッパの運動に関する数値解析 : オンバランス設計のスリッパのトライボロジー特性(OS12 フルードパワーの基礎と応用)

B30 斜板式アキシアルピストンポンプ・モータのスリッパの運動に関する数値解析 : オンバランス設計のスリッパのトライボロジー特性(OS12 フルードパワーの基礎と応用)

可変容量形ピストンポンプの加振力補償による騒音低減 補償効果の実験的検証

This paper deals with active noise control of a variable displacement swash plate type axial piston pump. The primary cause of noise generation of a piston pump is the exciting force due to sudden pressure change in the rotor cylinders. We tried a new method to compensate the pump exciting force by activating two built-in control cylinders using an electro-hydraulic servo valve and sinusoidal signals synchronous with the pump rotation. This method is not to suppress the exciting force itself but to prevent it from vibrating the pump and consequently to reduce the peak level of frequency components of the pump noise. Through the experiments, the exciting force compensation has been verified to be effective for noise reduction of a pump. The noise level could be reduced, for example, to 68 dB from 74 dB for the pump equipped with rubber vibration isolators, and to 70 dB from 82 dB without isolators.

Computer Aided Optimization of Bearing and Sealing Gaps in Hydrostatic Machines—The Simulation Tool Caspar

AbstractThe simulation tool CASPAR (Calculation of swash plate type axial piston pump and motor) is presented in this paper. Based on the simulation of the flow through the lubricating gaps in swash plate type axial piston machines the pressure, velocity and temperature fields in the considered gaps can be determined. This allows the calculation of the main losses generated in the machine due to viscous friction and gap flow. The individual gaps are connected in a complex way to each other. The calculation of the gap flow requires the determination of the instantaneous gap heights for all considered gaps. This is realized by solving the motion equation for all moveable parts of the rotating group. For determination of pressure dependent external forces the instantaneous pressure in the displacement chamber is calculated simultaneously. The program further calculates the instantaneous inlet and outlet flow of the swash plate machine for pumping and motoring mode as well as internal volumetric losses.

Investigations of the Temperature Behaviour of the Piston Cylinder Assembly in Axial Piston Pumps

In this paper the temperature behaviour of the piston cylinder assembly in swash plate type axial piston pumps is investigated. For the theoretical investigations a mathematical model is used that allows the calculation of the nonisothermal gap flow between piston and cylinder. For this purpose the Reynolds Equation, the energy equation and the equations of motion have to be solved. The gap flow and the pressure distribution in the gap is calculated by solving the Reynolds Equation numerically with a finite volume method. The temperature distribution is obtained by solving the energy equation over the piston cylinder assembly also numerically with a finite volume method. It is known that the piston undergoes an eccentric motion in the cylinder that has a significant influence on the gap flow. To calculate this motion a simplified equation of motion, based on the external forces, the hydrodynamic forces and the forces caused by elastic deformation, is used. A method is described that combines the calculation of these three equations and that allows calculation of the gap flow and the temperature distribution in the assembly depending on the design and the operating parameters of the machine. The experimental investigations were made on a standard pump that was modified for the measurements. The temperature distributions in the whole cylinder block of the machine and the dynamic pressure in the displacement chamber were measured under real operating conditions using a telemetry unit. The results were used to verify the simulation model.

DEVELOPMENT OF HIGH PERFORMANCE COMPONENTS FOR POLLUTION FREE WATER HYDRAULIC SYSTEM

In order to construct water hydraulic systems for environmental protection, we have developed a pollution-free water hydraulic pump and a water hydraulic servo valve. With a view to secure the same efficiency as oil hydraulic systems, we used a swash plate type axial piston pump, a spool type servo valve, and all parts are lubricated with water which is the hydraulic fluid. The system is made of ceramics, plastics, and so on. The water hydraulic pump has a mechanical efficiency of 94%, a volumetric efficiency of 86%, a power-to-weight ratio 1.0kW/kgf at the pressure of 21MPa, and a rotation speed of 1800min-1 The water hydraulic servo valve has leakage of under 760cm3/min and a response of 47Hz at a pressure of 21MPa. These components have the same performance as oil hydraulic system.

A new prediction method of operating moment and cylinder pressure of a swash plate type axial piston pump

A new prediction method of operating moment and cylinder pressure of a swash plate type axial piston pump

零傾角近傍における可変容量形斜板ピストンポンプの特性 （第２報 零傾角復帰方向のモーメントの理論解析）

零傾角近傍における可変容量形斜板ピストンポンプの特性 （第２報 零傾角復帰方向のモーメントの理論解析）