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.

A miniature single-piston valve flow-matching water-hydraulic pump is described in this paper, which designs with a unique double-face cam mechanism to achieve the reciprocating motion of the piston and a new flow-matching valve to adapt to the requirements of the frequency of flow-matching, and the use of a brushless DC motor to regulate the speed and control the flow of the pump. In this paper, the mechanical structure and working principle of this new type of water-hydraulic pump are described, the mathematical model of the valve flow distribution process is established, the transfer functions of the suction and drain process are obtained, and the relationship between the structural parameters of the distribution valve and the transient output characteristics of this type of water-hydraulic pump is simulated, and the simulation results show that the quality of the valve spool is the key factor affecting the switching speed of the distribution valve. The transient pressure and transient flow rate of the pump are studied experimentally, which reveals the pulsation law of the output characteristics of this single-piston pump, and lays a theoretical foundation for the design of a double-piston pulsation-free hydraulic pump.

For the hydraulic drilling tool under deep water, an integrated structure of a water hydraulic electrohydraulic motor is proposed, which consists of three parts: pump unit, motor unit, and DC brushless motor. The two-dimensional piston in the pump unit has two degrees of freedom of motion: rotation and reciprocation, so it is compact and can be matched with a high-speed motor to become a high-speed motor pump; the two sets of plungers in the motor unit are balanced with two end-facing cam drive mechanisms to achieve axial force, which is also suitable for high-speed rotation. In this paper, the mechanical structure and working principle of the electrohydraulic motor are described, the mathematical model of the output characteristics of the electrohydraulic motor is established, and the joint simulation model of Adams and AMESim is built, then the relationship between the dynamic characteristics of the electrohydraulic motor and the structure and working parameters is studied. The results show that the higher the speed of the pump unit, the smoother the characteristics of the electrohydraulic motor, when the motor speed is increased from 1000 r/min to 3000 r/min, the pulsation amplitude of the electrohydraulic motor speed is decreased by 200%; the plunger sub of the motor unit should take proper clearance, if the plunger sub clearance is increased to 12 μm, the output speed is decreased by 40% and the leakage volume is increased by 25 times; the motor unit should have proper back pressure to facilitate the smoothness and life of the motor, when the back pressure value is increased from 0.2 MPa to 1.2 MPa, the pressure pulsation at the beginning of the start-up is also greatly reduced.

This article presents the design of a two-dimensional (2D) piston pump flow-distribution port with an overlapped structure that reduces backflow in the pump chamber and pressure ripples at the pump outlet, thus minimizing vibration and noise caused by the high-frequency distribution process of a single two-dimensional (2D) piston pump. We describe the flow distribution structure and operation principle of the 2D pump, create a mathematical model of the pump chamber pressure by using the motion and flow continuity equations of the 2D piston, and use a Matlab program to compile and solve them. The influence of the flow distribution port overlap on the pump chamber pressure and the outlet flow rate was simulated. A prototype was designed and tested on a dynamic performance test bench. Our test bench results show that the flow distribution port overlap can reduce the pressure ripple at the pump outlet, which is consistent with the simulation results.

In a hydraulic system, a micro variable pump is required to be high pressure and high speed, and this work presents a new type of 2D bivariable pump structure in which the worm gear and worm mechanism are used to rotate the cylinder block to change the flow distribution state of the cylinder window and the piston groove to change the displacement of the 2D pump. The flow–pressure mathematical model of the 2D variable pump is established to analyze the relationship between pump displacement and the pump cylinder rotation angle and the effects of variable displacement on pump pressure characteristics, flow characteristics, and volume efficiency in Matlab. During the experiment, we tested the change in the corresponding pump output flow when the cylinder rotation angle is 0~12°, which verifies the correctness of the variable calculation model. The experimental results indicate that the volume efficiency and mechanical efficiency of the single-piston 2D pump are reduced to different degrees after variable displacement, the volume efficiency is reduced by approximately 3% at most, and the mechanical efficiency is reduced by approximately 5% at most.

The thrust system, an important subsystem of a tunnel boring machine (TBM), primarily provides thrust force and adjusts TBM’s attitude in real time. In the tunneling process, only controlling the thrust speed causes pressure oscillations, increases soil deformation, and leads to surface subsidence or upheaval. Conversely, solely relying on pressure control causes fluctuations in speed, making it difficult to ensure that the deviation between the designed tunneling axis (DTA) and the actual tunneling axis (ATA) remains within the permissible range. Due to the increase in geological complexity and higher construction quality standards, primarily relying on single-mode speed or pressure control has become inadequate to meet operational demands. Therefore, to realize higher safety and precise trajectory tracking, it is necessary to ensure speed and pressure compound control for thrust systems. This paper proposes a novel adaptive sliding mode control (ASMC) strategy for thrust systems, which is composed of a proportional pressure relief valve (PPRV) and a proportional flow control valve (PFCV). Firstly, PPRV and PFCV are modeled as a second-order system and an ASMC is employed to control the pressure and speed. Next, to assess the performance of the ASMC controller, simulation experiments were conducted under various conditions, including speed regulation, sudden changed load, and disturbed load. The simulation results indicate that compared to the Proportion–Integral–Differential (PID) controller, the ASMC controller shows almost no overshoot in speed and pressure control during the initial stages, with the response time reduced by approximately 70%. During speed regulation process and sudden changed load process, the response time for both speed and pressure control is shortened by about 80%. In the disturbed load process, the ASMC controller maintains pressure stability. In conclusion, the ASMC controller significantly improves the response speed and stability of the thrust system, exhibiting better control performance under various operating conditions.