Since many studies on axial piston pumps aim at enhancing their high power-weight ratio, many researchers have focused on the generated mechanical losses by the three friction pairs in such pumps and attempted to diminish them through abundant and new structural designs of the pump’s components. In this paper, a high-speed 2D piston pump is introduced and its architecture is specifically described. Afterward, a mathematical model is established to study the pump’s mechanical efficiency, including the mechanical losses caused by the viscosity and stirring oil. Additionally, in this study the influences of the rotational speed, the different load pressures, and the rolling friction coefficient between the cone roller and the guiding rail are considered and discussed. By building a test rig, a series of experiments were carried out to prove that the mechanical efficiency was accurately predicted by this model at low load pressures. However, there was an increasing difference between the test results and the analytical outcomes at high pressures. Nevertheless, it is still reasonable to conclude that the rolling friction coefficient changes as the load pressure increases, which leads to a major decrease in the mechanical efficiency in experiments.

The magnetic circuit of existing linear force motors does not consider the issue of energy utilization of permanent magnets, and the structure is complicated. To achieve high energy utilization and simplify the structure, this paper presents a novel magnetic circuit topology for the linear force motors of electro-hydraulic servo-proportional valves. In order to rapidly and accurately calculate the static characteristics of the force motor, an analytical model is established by using the equivalent magnetic circuit method. The model comprehensively considers the magnetic leakage effect, edge effect, and permeability nonlinearity. A prototype of the force motor is designed and manufactured, and a special experimental platform is built. The prototype force motor has a linear force-displacement characteristic and the output force increases with the increase of the excitation currents, which can reach about 41 N at 2 A. This indicates that it is suitable as an electro-mechanical converter for electro-hydraulic servo-proportional valves. Moreover, the analytical model is used to perform parameter optimization and calculate the magnetic flux density in the working air gap and the force-displacement characteristics under different excitation currents. The results are in good agreement with the electromagnetic field finite element simulation and experimental results. They indicate that the analytical model can rapidly and accurately predict the static characteristics of the force motor. The research work provides good reference means for the design of magnetic circuit topology with consideration of the high energy utilization of permanent magnets, and also the accurate analytical modeling of valve electro-mechanical converters.

In order to improve the volumetric efficiency of the axial piston pump, this paper proposes a novel stacked roller 2D piston pump. It utilizes the alternate communication between the distribution cylinder and the oil intake and discharge ports of the housing to realize the flow distribution. While removing the independent flow distribution mechanism of the traditional piston pump, the leakage loss at the distribution friction pair can be reduced to improve the volumetric efficiency. Based on the flow distribution principle, an analytical model of the volumetric efficiency of the stacked roller 2D piston pump was established. Then, a co-simulation model of the whole pump was built using both the Simulink and AMESim software. The variation curve of output flow and leakage flow under different load pressures and rotational speeds was obtained, as well as the influence of backflow, axial leakage, and circumferential leakage on the volumetric efficiency. On this basis, a prototype of the stacked roller 2D pump was designed and manufactured in order to measure the output flow under different load pressures and rotational speeds, and a dedicated test bench was established. The experimental results are consistent with the simulation results; when the rotational speed is 6000 rpm and the load pressure is 5 MPa, the volumetric efficiency of the prototype pump can reach 98.6%. The research work validates that the novel stacked roller 2D piston pump has high volumetric efficiency.

In this paper, a novel maglev coupling based on the opposed Halbach array is proposed as the interface between the linear electro-mechanical converter and 2D valve body. This non-contact maglev coupling possesses several advantages over existing mechanical couplings such as zero friction and wear, low vibration and noise, and no lubrication, which is expected to greatly improve the control accuracy and life cycle of the 2D valve. A detailed analytical model of maglev coupling is established based on the electro-magnetic theory. Firstly, the permanent magnets of the Halbach array is decomposed into several types of basic elements to obtain their individual analytical expressions, which are then re-superimposed into the whole coupling to obtain the analytical formula of torque–displacement characteristics. In order to obtain maximum output torque of maglev coupling, a parametric analysis was performed using an analytical model and optimal pitch angle and shifted distance was explored and found. To verify the correctness of the analytical modelling and parametric analysis results, the torque–displacement characteristics were also studied through both the FEM simulation and experimental approach. The results of analytical modelling, FEM simulation and experiment were in a good agreement, which shows that the maximum magnetic torque can reach about 0.579 N·m when the external armature displacement is 1 mm. The research work provides an important reference for the future application of maglev coupling in a 2D valve.

Although a two-dimensional (2D) valve has excellent performance, the processing of its spiral groove has a high cost and is time-consuming. This paper proposes a novel torque motor based on an annulus air gap (TMAAG) to replace the negative feedback function of the spiral groove to reduce the machining difficulty. In order to study the torque change law of the TMAAG, the air gap permeance was analyzed, and then a qualitative analytical model was established. Orthogonal tests were carried out to initially select the crucial parameters, which were further optimized through a back propagation (BP) neural network and genetic algorithm. The prototype of TMAAG was machined, and a special experimental platform was built, and experiment results are similar to the simulation values, which verifies the accuracy of the air gap analysis and qualitative model. For torque-angle characteristics, the output torque increases with both current and rotation angle and reaches about 0.754 N·m with 2 A and 1.5°. While for torque-displacement characteristics, due to the negative feedback mechanism, the output torque decreases with increasing armature displacement, which is about 0.084 N·m with 2 A and 1 mm. The research validates the unique negative feedback mechanism of the TMAAG and indicates that it can be potentially used as an electro-mechanical converter of a 2D valve.

We proposed a novel 2D electric feedback flow control valve to solve the problem of low integration and control accuracy of flow control valves. The torque motor of the valve drives the 2D piston to rotate, and the rotational motion is converted to axial motion and drives the spool. The differential pressure feedback rod on the valve body can accurately measure the differential pressure of the oil inlet and outlet and cooperate with the spool displacement to form a closed loop of flow. This loop of flow then overcomes the influence of the valve port’s load change on the flow. We first established the mathematical model of the valve, obtained the transfer function, and performed the stability analysis. Then, we used AMESim as a platform for simulation analysis. Finally, we conducted the experimental verification of the valve. The verification showed the following characteristics of the valve. The hysteresis loop is 4.4%. The linearity is 1.6%. The response time is about 44 ms. The amplitude bandwidth is about 17 Hz. The phase bandwidth is about 28 Hz. The valve’s steady-state flow error is less than 8%, suggesting its broad application prospect in the aerospace and military fields.