Abstract: Aiming at the problem that when the existing new hydraulic transformer realizes the function of pressure transformation, the inlet and outlet flow also changes, the oblique axis piston four-port hydraulic transformer(FHT), which can be directly connected to the original hydraulic system, is proposed, it can recover differential pressure energy, braking energy and gravitational potential energy without changing the original hydraulic system. The mathematical model of the transformation ratio is established and analyzed, it is found that the main factors affecting the pressure transformation ratio characteristics are the control angle of the valve plate, the speed of the cylinder main shaft and the recovery pressure difference. Then, according to the function of FHT, the prototype is designed and prototyped, and the four-port hydraulic transformer test device is built in the laboratory. The theoretical model of the transformation ratio is verified by experiments. The results show that the flow rate of port A is the same as port B, the combination of port A and B is equivalent to a hydraulic motor, the flow rate of port O is the same as port T, and the combination of port O and T is equivalent to a hydraulic pump, and the pressure ratio can be changed by adjusting the control angle of the valve plate. When the control angle of the valve plate is constant, the transformation ratio decrease as the cylinder speed increases or the recycling pressure difference decreases. The results not only lay a foundation for the further perfection of the theory of FHT, but also have important reference and guiding significance for its application.

Key words: four distribution ports, hydraulic transformer, pressure ratio, theoretical and experimental, energy saving