Valve Plate Research Articles

Finite Element Simulation and Structural Optimization of Structural Flow Sequential Field for Sequential Boost Switching Valve

Turbocharging technology is an important part of engine technology. Under the working condition of 730 °C and 0.5 MPa, the valve plate opening and closing will bear the high pressure of the internal fluid medium, resulting in the deformation of the switching valve. In this paper, ANSYS finite element simulation software is used to establish the valve fluid domain model, and the stress field and deformation law of the valve under the valve plate opening of 0 °~ 90 °are simulated and analyzed. Based on the fluid-solid coupling theory, the deformation and stress distribution of the valve plate structure are obtained by simulation analysis. The simulation results show that the smaller the opening of the valve plate, the more disordered the flow condition. As the opening increases, the flow tends to be stable. When the opening is 30 °, the negative pressure inside the valve is the largest; combined with the fluid-solid coupling analysis, the maximum stress load on the valve plate appears at the connection between the valve plate and the long valve shaft and the short valve shaft, and the maximum pressure appears at the opening of 60 °, which is 37.144 MPa; the maximum deformation occurs at the outer edge of the valve plate. Based on the results of this simulation analysis, the corresponding multi-objective structural optimization of the valve structure is carried out to provide technical reference for the structural design of similar valves.

The Leakage Current Characteristics of High-Gradient MOA Plate and Its Heating Analysis with Coatings under High-Frequency Overvoltage

High-frequency overvoltage generated in railways results in explosions of Electric Multiple Units’ (EMUs) arrestors. To solve this problem, the leakage current characteristics and heat transfer process of high-gradient MOA plates under high-frequency overvoltage has been studied. The leakage current characteristics of arrestor plates under high-frequency voltage was obtained and the element distribution has been analyzed. Heat transfer distribution and the thermal properties of the Metal Oxide Arrestor (MOA) have been modelled. According to the results, for a given voltage, the higher the harmonic frequency, the greater the leakage current of the arrestor valve plate, and the greater the resistive component of the leakage current. The Zn and O elements in high-gradient MOA plates are more uniform. Under the same leakage current as conventional ones, the undertake voltage of a high-gradient MOA plate will increase by 10%. Longtime high-order harmonic action will still significantly improve the core rod temperature when MOA plates are coated. The temperature rise in the power supply section of EMUs during operation is roughly 35 °C. This result will provide a foundation and supporting data for the applicability of high-gradient valve plates in railroads and coating improvements for traditional arrestor plates.

Forward design of the hydraulic system for the two-speed electric drive automatic transmission

The two-speed electric drive automatic transmission (2EDAT) is an effective scheme to improve the economy and power performance of electric vehicles. It is significant to carry out forward design, valve body improvement, and oil circuit optimization of the hydraulic system for 2EDAT. In the study, the functional requirement of 2EDAT hydraulic system was firstly analyzed and key parameters were calculated to determine the principle design of the hydraulic system. Then, the simulation model of the hydraulic system was established in the multidisciplinary dynamic simulation platform ITI-SimulationX and the changes in the pressure of the main oil circuit, the clutch oil pressure, and the cooling and lubrication flow in the shift process of the hydraulic system were simulated and analyzed. Furthermore, according to the principle scheme and constraint conditions of the whole machine, the overall layout and the hydraulic valve plate of the hydraulic system were designed and the valve plate and hydraulic system were tested on the bench. The test results of clutch pressure were 5.73%–13.12% lower than the designed value and did not meet the design requirements. Finally, according to test results, the processing defects of the pressure reducing valve were mitigated and the main oil circuit was optimized for another test of the valve plate and the hydraulic system. The test results of clutch pressure were 0.35%–8.60% higher than the designed value and met the design requirements. The results showed that the optimized hydraulic system realized the better control effects on the main oil pressure and clutch oil pressure in the shift process, including the fast and accurate clutch shift response, the sufficient cooling and lubrication flow, and smooth working conditions.

Investigation of the Pressure Fluctuation of Piston Chambers with Variable Slot Geometry

High-pressure fluctuation and flow ripple may cause unexpected vibration and noise when the piston pump works under severe conditions, and eventually lead to hydraulic transmission failure. The geometry of the valve plate has a great influence on the pressure fluctuation of the piston chamber. In order to optimize the structure of the valve plate, a mathematical model considering the slot geometry and the flow leakage of the lubricating interfaces was established in this paper. The model was used to investigate the pressure of the piston chamber, and then the accuracy of the model was validated by comparing simulation and experimental results. Further simulation results show that the pressure fluctuation in the piston chamber can be effectively suppressed by optimizing the triangular slots parameter of the valve plate, and a good design of the slot geometry could reduce the undershoot and overshoot of the pressure in piston chamber at the starting moment.

Distribution Mechanism of Asymmetric Axial Piston Pump

Pump-controlled single-rod hydraulic cylinders are energy-saving and efficient, which is the development direction of hydraulic systems in the future. However, the flow imbalance caused by the unequal effective areas of the two chambers of single-rod hydraulic cylinders has always restricted the development and application of pump-controlled single-rod hydraulic cylinders. The flow rate of the inlet and outlet ports of the ordinary axial piston pump is equal and the flow rate of the large and small chambers of the single rod hydraulic cylinder does not match. In order to solve this problem, the ordinary axial piston pump is improved into an asymmetric axial piston pump, on this basis, the flow distribution mechanism of the asymmetric axial piston pump is explored, and the design theory of the asymmetric axial piston pump is improved. Theoretical analysis of the relationship between the angle of the distribution window of the asymmetrical axial piston pump and the area ratio of the single-rod hydraulic cylinder is carried out, and its mathematical model is derived. Design of valve plates for asymmetrical axial piston pumps to match single rod hydraulic cylinders with different area ratios. The physical model of the asymmetrical axial piston pump and the asymmetrical axial piston pump controlled single-rod hydraulic cylinder system was established in the computer simulation software AMESim. The simulation analysis of the inlet and outlet flow of the asymmetric axial piston pump under different working conditions and the matching of the asymmetric axial piston pump and the single-rod hydraulic cylinder with different area ratios. The simulation results show that the use of an asymmetrical axial piston pump can compensate the flow imbalance caused by the unequal effective areas of the two chambers of the single-rod hydraulic cylinder, so that the flow of the asymmetrical axial piston pump and the single-rod hydraulic cylinder can completely match.

Effect of solid particles in oil on tribological characteristics of the valve plate friction pair of a high-pressure vane pump

The friction pair wear in a high-pressure vane pump caused by solid particles in oil is a significant factor that affects the pump's service life. The study investigates the effects of solid particles on the tribological characteristics of the valve plate friction pair of a high-pressure vane pump. The effects of varying solid particle diameters (5–20 μm) and concentrations (0.001–0.015%) on the friction coefficient, wear rate, and surface morphology of the valve plate friction pair in a high-pressure vane pump were investigated. In addition, to study the effect of diameter and concentration of solid particle on the vane pump's volumetric efficiency, the volumetric efficiency of the vane pump was tested. According to the results, when the solid particle concentration was 0.001%, the friction coefficient increased first and then decreased as the solid particle diameter increased, with no obvious running-in process. Furthermore, the wear rate increased first and then decreased as the solid particle diameter also increased. When the solid particle diameter was greater than 15 μm, the friction coefficient decreased as the concentration increased, and a distinct running-in process was unobserved. During this time, the relationship between the valve plate's wear rate and the solid particle concentration was approximately linear. The wear of the valve plate with solid particles included the impact of scraping wear as well as the abrasive wear and slight adhesive wear caused by solid particles. The vane pump's volumetric efficiency decreased as the solid particle diameter increased with a linear relationship. The volumetric efficiency of the pump also showed a downtrend when the solid particle concentration increased. This research provides a reference for valve plate design and improving the performance of high-pressure vane pumps.

APPLICATION OF METAL-MATRIX COMPOSITES IN REPAIR AND RECOVERY TECHNOLOGIES (ON THE EXAMPLE OF ICE VALVE)

Traditional technologies for building restorative coatings have exhausted their resource and their use does not provide the required economic indicators. Therefore, the issues of finding innovative approaches in repair production remain relevant and require a fundamental approach. (Research purpose) The research purpose is studying the possibilities of using thin metal matrix composites in repair and restoration coatings. (Materials and methods) Used a metal composition based on a metal matrix - nickel, additionally reinforced with boron carbide and zirconium oxide and applied to the working surface of the valve plate of the internal combustion engine. For the first time, the technology of selective laser sintering was used in the formation of thin reducing coatings under conditions of short-pulse laser reflow of powder media. To assess the heat resistance of the analyzed coating, we have developed a method for testing the temperature resistance of valves, simulating the operation of the valve mechanism of an internal combustion engine. Tribological indicators of coatings were studied using modern techniques and instrumentation to study anti-wear properties. (Results and discussion) Confirmed the possibility of practical implementation of restorative coatings based on metal composite compounds. The restorative coatings studied on the surface of the valve plates of internal combustion engines showed an increase in the wear resistance of the interfaces up to 480 percent. Higher temperature resistance and bully resistance of the contacting surfaces were observed under conditions of oil starvation and dry friction. It was revealed that the decrease in the wear resistance of coatings is determined by a decrease in the coefficient of friction due to the action of tribofilms formed as a result of high temperatures in the friction zone and resistant to dynamic and kinematic loading. (Conclusions) The presented research results have high scientific potential and practical significance. Their use will increase the reliability and durability of machine parts in the conditions of repair and machine-building production.

Development of a pneumatic actuated low-pressure direct injection gas injector for hydrogen-fueled internal combustion engines

Mixture formation is one of the greatest challenges for the development of robust and efficient hydrogen-fueled internal combustion engines. In many reviews and research papers, authors pointed out that direct injection (DI) has noteworthy advantages over a port fuel injection (PFI), such as higher power output, higher efficiency, the possibility of mixture stratification to control NOx-formation and reduce heat losses and above all to mitigate combustion abnormalities such as back-firing and pre-ignitions. When considering pressurized gas tanks for on-vehicle hydrogen storage, a low-pressure (LP) injection system is advantageous since the tank capacity can be better exploited accordingly. The low gas density upstream of the injector requires cross-sectional areas far larger than any other injectors for direct injection in today's gasoline or diesel engines. The injector design proposed in this work consists of a flat valve seat to enable the achievement of lifetime requirements in heavy-duty applications. The gas supply pressure is used as the energy source for the actuation of the valve plate by means of a pneumatic actuator. This article describes the design and the performed tests carried out to prove the concept readiness of the new LP-DI-injector.

Design and Analysis of a New Pressure Relief Valve for Oil-Immersed Electrical Equipment

Abstract Internal arcing in oil-immersed electrical equipment is inevitable and of great danger. Transient overpressure should be released by protectors quickly and controllably. Currently available pressure relief valves cannot fully protect the electrical equipment due to mismatch between insufficient relief capacity with correspondingly weak valve structure and increasing arcing energy in upgrading electrical systems. Additionally, flaming possibility of ejected high-temperature oil–gas mixture is distinct, and retained oil in an oil tank without any isolation may be ignited by the flame. Unfortunately, resealing of some existing single-outlet valves is out of control due to asymmetrical hydraulic pressure distribution on the valve plate which causes unstable valve plate movement. Therefore, a new pressure relief valve characterized by symmetrical outlets and improved pressure relief capacity was developed. The novel structure and function of the new valve was first introduced, and comprehensive analysis regarding dynamic performances, strength and fluid development during the relief process were conducted. Finally, a prototype was manufactured and tested on a specific arcing test system. The developed valve can well release the overpressure generated by a 6 MJ equivalent arcing fault without any flame during the entire relief process. Furthermore, the valve structure can withstand the pressure load, and valve plate can precisely reseal the oil tank due to optimized fluid pressure distribution. This research provides an optimized pressure relief valve and a design guide for improved pressure relief valve.

Two New Free-Living Marine Nematode Species of the Genus Haliplectus Cobb, 1913 (Haliplectidae) from Mangroves of Shenzhen, Guangdong Province, China

This study presents two new free-living marine nematodes, Haliplectus major sp. nov. and Haliplectus futianisus sp. nov., from a mangrove reservation in Shenzhen, China. Haliplectus major sp. nov. can be distinguished by its total body length of 1615–1998 µm; a cuticle annulated with eight rows of cuticle pores; amphidial fovea at 9–12 µm from the anterior end; a bipartite basal bulb with striated valve plates in both sexes; five to seven closely spaced precloacal supplements in males; a didelphic reproductive system in females, with the vulva at 49.64–52.37% of body length; and sexual dimorphism in tail shape, arcuate-conoid and 2.3–3.2 times anal body diameter long in males and elongate-conid and 3.5–4.2 times anal body diameter long in females. Haliplectus futianisus sp. nov. is characterized by a total body length of 574–655 µm; a cuticle annulated with eight rows of cuticle pores; amphidial fovea at 8–11 µm from the anterior end; a monopartite basal bulb with unstriated valve plates in both sexes; an absence of precloacal supplements in males; and a didelphic reproductive system in females, with the vulva at 42.33–45.63% of body length. The identification was confirmed by analyzing morphological characteristic and 18S rRNA gene sequences. The maximum likelihood (ML) topology was regarded as morphological evidence of H. major sp. nov. and H. futianisus sp. nov. being two distinct species.

Study on the Thermohydrodynamic Friction Characteristics of Surface-Textured Valve Plate of Axial Piston Pumps.

The purpose of this paper is to study the oil film and friction characteristics of valve plates with a micro-textured surface and to explore the influence of textures of different shapes and sizes on the valve plates. Firstly, on the basis of thermohydrodynamic theory, this paper established the lubrication model of the oil film on the valve plate pair of swashplate axial piston pumps, according to the Reynolds equation. Secondly, the micro-texture was added to the mathematical model of the valve plate pair's oil film. A combination of the energy equation, oil-film-thickness equation, elastic deformation equation, viscosity-pressure and viscosity-temperature equation, the finite difference method, as well as the relaxation iteration method, was used to solve the problem, and the textured and non-textured valve plate surfaces were simulated. The nephogram of the oil-film-thickness distribution, elastic deformation distribution, oil-film-pressure distribution and oil-film-temperature distribution were generated. Then, the control variable method was used to change the cylinder rotational speed, tilt angle, oil viscosity, initial oil film thickness and other parameters to analyze their effects on oil film characteristics. In addition, the friction characteristics of non-textured surfaces, square textured surfaces, triangular textured surfaces and circular textured surfaces were compared and analyzed. It was found that the textured surface of valve plates can obviously improve friction efficiency under the same operating conditions. The square texture, especially, is the preferable shape, rather than the triangular texture and the circular texture, and the friction performance is at its best when the texture depths are between 20 μm and 50 μm. The results provide a theoretical basis for the design and improvement of the valve plate.

Study on noise reduction method of main noise transmission path of axial piston pump with new damping material

Axial piston pump is complex fluid machinery with mechanical fluid coupling, and it has the characteristics of multiple noise sources. In order to solve the high noise problem of axial piston pump, this paper proposes a noise reduction method by identifying the main noise sources of axial piston pump and laying new damping materials to reduce noise. It breaks through the existing method of optimizing the parameters of piston pump shell and valve plate structure. A multi-parameter trajectory sensitivity identification and noise reduction method for vibration transmission path of axial piston pump is proposed in this paper. First, the lumped parameter method is used to establish the mathematical model of vibration transmission path of axial piston pump. The sensitivity of structural vibration response to transmission path multi-parameters are analyzed based on trajectory sensitivity method. The most sensitive parameters in the main noise transmission path are determined. Then, the experimental study of radiated noise transmission path of axial piston pump is carried out. A new type of viscous damping material is proposed to reduce the noise on the transmission path of the main noise source. The experimental results show that the noise of piston pump is reduced by 2.32 dB. The research results provide a new method and way for the design and manufacture of low noise piston pump.

Design and Testing of a Prototype Eddy Current Actuated Valve for the ITER Shattered Pellet Injection System

Reliably mitigating disruptions is essential for ITER to meet its long-term operational research plan without damage to the in-vessel components. Currently, the shattered pellet injection (SPI) technique is the most effective radiator of thermal energy and has been chosen for the baseline disruption mitigation system (DMS) for ITER. The SPI process uses cryogenic temperatures to desublimate material into the barrel of a pipe gun forming a solid cylindrical pellet. Pellets for ITER will initially be hydrogen and hydrogen–neon mixtures. Once formed, pellets are dislodged and accelerated using high-pressure gas (40–60 bar) delivered by a fast-opening valve. The solenoid valves currently used for SPI experiments will not operate in an ITER environment due to the large background magnetic field. An ITER prototype fast-opening valve, called a flyer plate valve (FPV), has been designed and has undergone a wide range of testing. The FPV operates by pulsing current through a pancake coil that is closely coupled with a “flyer plate.” The flyer plate is an aluminum plate in which eddy currents are generated creating a repulsive force from the pancake coil. The force generated in the flyer plate rapidly lifts the valve tip off the seat and delivers a pulse of gas to the rear of the pellet, breaking it free from the barrel and accelerating the pellet downstream to its intended target. The design of the valve has been iterated on over the lifetime of this project, as the DMS for ITER shifted from massive gas injection (MGI) to SPI. The most recent design has been tested, and operational ranges have been mapped. The valve must survive 3000+ cycles in an ITER-like magnetic field. The principal functional requirement of this valve is to reliably dislodge and accelerate hydrogen (or H–Ne mixture) pellets into ITER. The valve was mated with an ITER SPI test stand and has been shown to be capable of launching pellets reliably. The valve and power supply design will be discussed in this article, along with the various testing setups used to determine the feasibility of this valve for use on ITER.

Effect of controlled operating pressure on physical optical and electrical properties of AZO thin film by DC magnetron sputtering technique

The study aimed to research the controlled operating pressure in the range of 1.10 × 10–2 − 2.60 × 10–3 mbar with the adjustment position of plate valve (40 – 100%) using DC pulsed magnetron sputtering system. The AZO films were prepared onto n-type silicon (100) and glass slide substrates. A comparison, all samples were assigned 400 nm of AZO film thickness and then the prepared AZO films were investigated by field-emission scanning electron microscope (FE-SEM) for surface morphologies, X-ray diffraction (XRD) for crystallinity, UV-Vis-NIR spectrophotometry for optical property, Four-point probe and Hall effect instrument for electrical properties, respectively. The results from FE-SEM image showed that the AZO film was columnar structure. The XRD patterns of AZO films demonstrated the crystal growth direction which preferred AZO growth was indicated the (polycrystalline) hexagonal wurtzite structure. For the optical property, the transmittance (%T) clearly showed transparent film, indicating good average value which was 81.54 – 83.28% in visible region (380 to 780 nm of wavelength). Furthermore, the sheet resistivity, high mobility and carrier concentration displayed 91.48 Ohm sq−1, 3.40 cm2 Vs–1 and 7.00 × 1020 cm–3, respectively. These results were decided that the position of plate valve of 85% with operating pressure of 2.70 × 10–3 mbar was the optimal condition. Finally, the excellent electrical and good optical properties of AZO film is mainly applied in several application for optoelectronic device and solar cell.

Research on the electrical performance variation characteristics of internal damp roof arrester of EMU

In order to study the reason of performance deterioration of roof arrester, this paper conduct the disassembly inspection of the burst arrester, and conducts the SEM test and EDS test to the valve plates, and the microscopic variation characteristics of the valve plates were analyzed and the electrical parameters variation characteristic under different internal damp was studied. Microscopic test results show that the white matter on the valve plate surface is caused by moisture oxidation of the aluminum spray layer. The results of simulation damp test show that the DC reference voltage decreased obviously, it is only 55.2 kV even under mild damp, which is lower than the standard value of 58.0 kV. At the same time, the leakage current rises to 46 μA under 0.75 times of DC reference voltage, and the full current reaches 1.21 mA under 42 kV with AC voltage. The peak value of the fundamental wave of the resistive current reached 1.35 mA.

The effect of discharge areas on the operational performance of a liquid-ring vacuum pump: Numerical simulation and experimental verification

To determine the effect of discharge area on the ability of a liquid-ring vacuum pump, the inspiratory capacity and shaft power are numerically investigated for different discharge areas adjusted by the number of discharge ports at different inlet pressures. Besides, the numerical results of these key operating parameters are verified by experiments in a developed testing system with a flexible valve plate on the discharge ports. The result shows that there exists an optimal discharge area of the liquid-ring vacuum pump at each inlet pressure, and good agreements are found between the experimental data and numerical results. For a 2BEC-40 vacuum pump, the maximum isothermal compression efficiencies can reach 39.99%, 46.80%, 49.16% and 40.82% for the inlet pressures of 20 kPa, 40 kPa, 55 kPa and 70 kPa with the optimum number of discharge ports is 1, 5, 12 and 12, respectively. The results suggest that the self-adaptive adjustment of discharge areas by the valve plates is of great importance to practical applications of a liquid-ring vacuum pump.

Study on the Measurement of the On-Site Overvoltage and Internal Temperature Rise Simulation of the EMU Arrester

In order to analyze the explosion accidents of the CRH5 EMU roof arrester in recent years, an internal temperature measuring platform based on fluorescence fiber was established, and the temperature distribution characteristics under the continuous operating voltage and high-current impulse were analyzed. The test results show that passing section overvoltage and steep impulse overvoltage have higher amplitudes, while high-harmonic overvoltage has a lower amplitude but a longer duration. The maximum temperature rise of the arrester was 5.2 °C under 34 kV for 3 h. The surface temperature of the valve plate column was high in the middle and low on both sides; the maximum temperature difference at different positions was only 2.2 °C. The maximum temperature of the valve plate column rose to 97.6 °C under 105 times of the high-current impulse, and the maximum temperature difference at different positions reached 33.8 °C. Then, the actual overvoltage of the arrester in operation was measured and analyzed statistically, and the arrester simulation model was established. The temperature characteristics of the normal arrester and the arrester with the electric tree were studied under the actual typical overvoltage, and the influence of air velocity on the internal temperature rise was analyzed. The simulation results show that, due to the low amplitude and small current of high-harmonic overvoltage, the internal temperature rise of the normal and defective arresters was very small. Under the effects of passing section overvoltage and steep impulse overvoltage, the internal temperature of the normal arrester can reach 36.57 °C and 241 °C, and the arrester with the electric tree defect can reach 44.75 °C and 536 °C, respectively. The air velocity has little effect on the internal temperature rise of the arrester. Passing section overvoltage and steep impulse overvoltage occur frequently and have an obvious influence on the internal temperature rise of the arrester, so the roof overvoltage of the EMU is an important reason for the arrester burst.

Analysis of pressure at transition zone of valve plate of radial piston pump

In present studies focuses on the characteristics of flow-pressure of piston cylinder barrel and silencing groove chambers near the transition zone of valve plate of a fixed displacement radial piston pump. The designing of silencing groove of valve plate of the pump is carried out with appropriate geometrical configuration, compute the orifice area of piston kidney over the silencing grooves and manifolds, the interaction area make a key role in fluid flow interaction. The pressure and flow of pump is analyzed in consideration the silencing groove as separate control volume from manifold, each silencing groove chamber is connected to the both end of the manifold chamber, the shape of the silencing groove is an asymmetric tetrahedron. The radial piston pump is modelled in simulation with consideration of five pump pistons barrel, analyses the pressures near at transition zone with different bridge angle. The flows interaction of pump piston cylinder barrel with silencing groove chamber and manifold chamber are also carried out. The overall pump volumetric efficiency, flow and pressure fluctuation of radial piston pump are analyzed to optimize the pump.

Research on Degradation State Recognition of Axial Piston Pump under Variable Rotating Speed

Under the condition of variable rotating speed, it is difficult to extract the degradation characteristics of the axial piston pump, which also reduces the accuracy of degradation recognition. To address these problems, this paper proposes a degradation state recognition method for axial piston pumps by combining spline-kernelled chirplet transform (SCT), adaptive chirp mode pursuit (ACMP), and extreme gradient boosting (XGBoost). Firstly, SCT and ACMP are proposed to deal with the vibration signal instability and high noise of the axial piston pump under variable rotating speed. The instantaneous frequency (IF) of the axial piston pump can be extracted effectively by obtaining the accurate time-frequency distribution of signal components. Then, stable angular domain vibration signals are obtained by re-sampling, and multi-dimensional degradation characteristics are extracted from the angular domain and order spectrum. Finally, XGBoost is used to classify the selected characteristics to recognize the degradation state. In this paper, the vibration signals in four different degradation states are collected and analyzed through the wear test of the valve plate of the axial piston pump. Compared with different pattern recognition algorithms, it is verified that this method can ensure high recognition accuracy.

Study on the Influence of Flow Distribution Structure of Piston Pump on the Output of Pulsation Pump

According to the working principle of the A10VNO swashplate axial piston pump, the output flow model of an axial piston pump in an ideal state and the output flow theoretical model of an axial piston pump considering the leakage and flow distribution process are established. The output flow pulsations of odd and even piston pumps are simulated and analyzed by Matlab, and the influence of a closed dead angle and a mismatch angle of the port plate on the output flow pulsation of the pump is obtained. Based on the theoretical model, AMESim is used to establish the overall model of the axial piston pump considering leakage, flow distribution process and oil compressibility under constant working conditions. By setting six different flow distribution boundary conditions corresponding to the theoretical research, the influence of flow distribution plate structure on pump output flow pulsation is studied. A test-bed was built and verified by experiments. The results show that when the mismatch angle of the valve plate is 3–5° and the dead angle is 6–10°, the difference between the output flow pulsations of the odd and even piston pumps is very small, so in the hydraulic pump hydraulic motor system, when the hydraulic pump is used as a hydraulic motor under the condition of power recovery, the odd number or adjacent even number of hydraulic motors are appropriate.