Design Of Two-Dimensional Cartridge Pressure Valve And Research On Damping Stabilization Technology

In the development of modern hydraulic technology,the cartridge valve stands out in various connection modes due to its simple structure and easy integration,which has become the development direction of hydraulic valves.The pilot valve and the main valve of the electro-hydraulic pressure servo valve are placed in parallel and cannot be inserted,so the power-to-weight ratio cannot be further improved.The two-dimensional servo valve based on the servo screw mechanism integrates the pilot stage and the power stage on a 2D moving valve spool,and the torque motor and the valve spool are arranged axially,which conforms to the structural requirements of the cartridge valve.While common pressure servo valves are pursuing higher pressure gains,its stability will decrease,which is easy to form self-oscillation.In order to suppress the occurrence of this phenomenon,the stability of the system is usually increased by using a damping hole,a throttle groove or a squeeze oil film.However,the orifice affects the response speed and accuracy of the servo valve.There is pressure loss in the throttle groove.The squeeze film limits the displacement of the spool.At the same time,they ignore the influence of temperature on the stability of the pressure valve.Aiming at the above two shortcomings of common pressure valves,this paper designs a new type of two-dimensional cartridge electro-hydraulic pressure servo valve,which makes the structure simpler,the power-to-weight ratio is further improved.Moreover,the damping piston structure with the material of polyoxymethylene is added to the pressure servo valve,which not only avoids the above problems,but also has the function of temperature compensation.Therefore,the main contents and research results of this paper are as follows:(1)According to the characteristics of 2D servo valve,a new type of 2D cartridgepressure valve is proposed and the specific principle is explained.Then the structural design is elaborated in three aspects: valve body module,electro-mechanical converter module and displacement sensor module.(2)The transfer functions of the 2D valve assembly and the main valve assembly are respectively established,and the stability analysis of the two is carried out in consideration of the cavitation.The resonance phenomenon of the main valve assembly is analyzed and the effect of the presence or absence of damping on the resonance peak of the system is investigated by means of energy conservation.Finally,the relationship between the viscous damping coefficient and the resonance peak is obtained,which provides a basis for the study of the subsequent damping technique.(3)A new type of damping piston structure is proposed and the principle is described and a mathematical model is established.Then the formula of the viscous damping coefficient provided by the damping piston structure is derived.The relationship between the viscous damping coefficient and the diameter and length of the damping piston,the diameter of the valve core,the gap between the damping piston and the valve sleeve and the viscosity of the oil are investigated through the matlab.Finally,considering the effect of temperature on the viscosity of the oil,the material of the damping piston is changed to polyoxymethylene with a large linear expansion coefficient,so that the damping provided during the temperature change is kept in a small range,which called temperature compensation.(4)For the above research,the design experiment was verified.Firstly,the damping piston is heated and cooled,and its size is measured to see that the change does meet the theoretical dimensional change,which verifies the feasibility of temperature compensation.The experimental platform was then built to explore the performance of the 2D cartridge electro-hydraulic pressure servo valve.The spool displacement hysteresis is 1%,the pressure hysteresis is 3%,the spool displacement frequency response is 50 Hz,the pressure frequency response is 35 Hz,and the pressure fluctuation ratio at 5-10 MPa is 5-6%,which meets the design requirements.The 2D cartridge electro-hydraulic pressure servo valve designed in this paper is not only simple in structure,easy to integrate,high in power-to-weight ratio,but also has high stability and temperature compensation,which is very suitable for aerospace.