Flow characteristics of integrated motor-pump assembly with phosphate ester medium for aerospace electro-hydrostatic actuators

Zhao, Jingcheng; Fu, Jian; Li, Yuchen; Qi, Haitao; Wang, Yan; Fu, Yongling

doi:10.1016/j.cja.2022.11.013

Cited by 9 publications

(5 citation statements)

References 30 publications

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“…The net Couette flow equals zero due to the even distribution of pistons in the cylinder block around its centerline. Therefore, the Couette flow term can be dropped and the Poiseuille flow term is remained in equation (30). The Poiseuille flow can be further divided into two parts on the discharge and suction sides.…”

Section: Piston/cylinder Block Interfacementioning

confidence: 99%

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New analytical leakage models for tribological interfaces in axial piston pumps

Chao

Shao

Liu

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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Axial piston pumps act as the power source in hydraulic systems and their volumetric losses mainly arise from leakage of tribological interfaces. The leakage of tribological interfaces was often modeled as a simple mixture of pressure-induced flow and velocity-induced flow in previous studies. However, few studies have clarified the contribution of discharge pressure and rotational speed to the leakage flow. This work considers both pressure and velocity factors and establishes new analytical models for the leakage of tribological interfaces from Navier-Stokes equations. Experiments were performed on an actual axial piston pump to measure its leakage flow rates at different discharge pressures and rotational speeds. Results show that the total pump leakage excludes Couette flow and only includes Poiseuille and centrifugal flows. The Poiseuille flow predominates the pump leakage while the centrifugal flow contributes little to the pump leakage.

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Section: Piston/cylinder Block Interfacementioning

confidence: 99%

“…The second is Couette flow due to piston reciprocation in the cylinder bore. For two parallel rectangular plates, the combined Poiseuille flow 29,30 and Couette flow in a single piston/cylinder block interface is given by…”

Section: Mathematical Modelingmentioning

confidence: 99%

New analytical leakage models for tribological interfaces in axial piston pumps

Chao

Shao

Liu

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…In the relevant research, the parameters of the plunger, cylinder block and valve plate are necessary [1]. And the main parameters of the motor are listed in Table 1.…”

Section: σMmentioning

confidence: 99%

“…The oil-immersed motor pump is a novel electro-hydraulic integrated power unit comprising an axial piston pump and a motor, exhibiting remarkable advantages of high efficiency, compact size, high energy utilization rate, high power density, and extended lifespan. It constitutes the essential component of the rudder control system for future large airliners and advanced warplanes, and represents a critical technology for the realization of intelligent actuation of high-end equipment [1][2][3]. However, due to its high-speed operation, it generates considerable heat within a limited time [3].…”

Section: Introductionmentioning

confidence: 99%

Thermal-Hydraulic Modeling of Oil-Immersed Motor Pump

Shi,

Li,

Gao

et al. 2023

Applied Sciences

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The integrated design of the motor and axial piston pump eliminates the coupling structure, resulting in a compact and lightweight motor-pump structure. The challenge of motors overheating has always been a major concern. To address this issue, the hydraulic oil throughout the motor pump is utilized for cooling the high-speed motor, effectively improving the power density and heat dissipation capability of the hydraulic power unit. This integrated design approach has successfully resolved the significant issue of overheating motors, leading to enhanced performance of the hydraulic power unit. To address this concern, the entire motor pump’s oil is utilized to cool the high-speed motor. Consequently, the thermodynamic prediction of high-speed motor pumps has become increasingly important. In this study, the impact of motor heat generation on hydrodynamics is analyzed, and the heat transfer of the motor pump is investigated using the control volume method. Furthermore, thermodynamic models of hysteresis loss, eddy current loss, alternating current loss, churning loss, and throttling loss are established for the oil-immersed motor pump. The change in oil viscosity is also considered. The instantaneous temperature change rule of the oil within the oil-immersed motor pump is derived. Additionally, the influence of various working conditions such as pressure and speed on the temperature of the motor pump’s key node is examined. The experimental results indicate the accuracy of the thermodynamic calculation, and the significant effect of motor loss on the leakage temperature.

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“…Studies have shown that the flow characteristics of the EHA pump could be quite severe in a low speed and high-pressure environment. 11 The change of pressure and speed makes the working condition strict, especially exposing challenges when designing the main friction pairs 12 of the EHA pump (slipper/swash plate interface, 13,14 cylinder block/valve plate interface, 15 and piston/cylinder block interface 16 ). The volumetric losses mainly arise from leakage of tribological interfaces.…”

Section: Introductionmentioning

confidence: 99%

Tribological characteristics of hard-to-hard matching materials of cylinder block/valve plate interface in electro-hydrostatic actuator pumps

Fu,

Lyu,

Kang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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Axial piston pumps, serving as the essential power component in electro-hydrostatic actuators (EHA), play a crucial role in achieving advanced actuation by ensuring high efficiency and reliability. The cylinder block/valve plate interface, which is the greatest contact area inside the axial piston pump, significantly affects both leakage and energy dissipation. The interface experiences significant friction loss and severe wear in aerospace applications, primarily due to the rapidly changing mixed and boundary lubrication conditions under a wide range of speed and pressure. Therefore, to improve the efficiency and reliability of electro-hydrostatic actuators, strengthening the cylinder block/valve plate interface is a key problem to overcome. Previous studies have demonstrated that the utilization of soft-to-hard matching materials enhances the friction characteristics of the interface, but it also results in relatively severe wear on the soft material. Therefore, in this study, we propose the concept of employing hard-to-hard matching materials as a strategy to mitigate wear in axial piston pumps. An optimized friction simulation test apparatus is adopted, which contains a simulated piston structure to take the piston stirring effect into consideration. Experimental results show that the implementation of hard-to-hard materials leads to a substantial improvement in the wear resistance of the interface under a wide range of rotational speed (300–6000 rpm). The wear depths of the TiAlN/TiAlN (hard-to-hard) matching material are only 28.6%~34.7% of the tin bronze/TiAlN (soft-to-hard) matching material. Besides, compared with traditional tin bronze/nitrided (soft-to-hard) matching material, the hard-to-hard matching materials improve both friction and wear performance. The hard-to-hard matching materials provide a novel approach to reinforce the cylinder block/valve plate interface, and thus to promote volumetric efficiency and extend the service life of the axial piston pump.

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Flow characteristics of integrated motor-pump assembly with phosphate ester medium for aerospace electro-hydrostatic actuators

Cited by 9 publications

References 30 publications

New analytical leakage models for tribological interfaces in axial piston pumps

New analytical leakage models for tribological interfaces in axial piston pumps

Thermal-Hydraulic Modeling of Oil-Immersed Motor Pump

Tribological characteristics of hard-to-hard matching materials of cylinder block/valve plate interface in electro-hydrostatic actuator pumps

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