Research On Sealing Characteristics Of Variable Gap Sealing Hydraulic Cylinder And Design Of Measurement And Control Test Bench

Hydraulic cylinders are important actuators of hydraulic systems,and their performance directly affects the working efficiency of the entire hydraulic system.The sealing method of the traditional hydraulic cylinder hydraulic cylinder piston adopts the contact sealing of the sealing ring.The reliability and service life of the hydraulic cylinder are restricted by the failure of the sealing ring,so that the hydraulic system cannot work in a long-term and efficient manner.For this reason,research on non-contact sealing of pistons has been carried out at home and abroad.The variable gap sealing hydraulic cylinder is used as a non-contact sealing cylinder for special piston structure.The axially symmetric annular groove is formed at both ends of the piston to form a deformable lip and lip.The amount of deformation of the edge changes as the pressure of the high pressure oil chamber changes.The utility model has the characteristics that the piston lip can be deformed,the piston leakage amount is adaptively adjusted with pressure,and the high frequency is loud.In this paper,the deformation trajectory of the piston lip of the variable gap seal hydraulic cylinder under different pressures and lip lengths,the theoretical study of the flow loss of the variable clearance field,the leakage analysis under different piston structures and the automation design of the test and control test bench are as the following research.(1)Applying the theory of elastic mechanics to the mechanical model of thick-walled cylinder for short-lip structure piston,formulating the deformation trajectory of short-lip edge;using Workbench simulation for long-lip structure and fitting the deformation of lip The trajectory;the result shows that the deformation of the short lip is a bell mouth shape,and the deformation amount is proportional to the product of the pressure and the length of the lip.The deformation of the long lip is the deformation of the front segment of the bell mouth to the waist drum shape.(2)Based on the theoretical analysis of the flow field of the constant gap seal,theflow model of the variable gap flow field is established,and the theoretical formula of the leakage of the variable gap seal is derived.Then the CFD simulation analysis is used for different piston structures.It is concluded that the sealing effect of the grooved structure with the variable clearance lip is the best.The number of uniform pressure grooves uniformly distributed on the piston will affect the leakage of the hydraulic cylinder.The more the number of pressure equalization grooves,the larger the leakage amount.(3)The shortcomings of the complicated operation and low efficiency of the original measurement test bench.The original hydraulic system was improved,and the closed-loop control of the PLC and the independent movement of the loading cylinder were adopted.The data acquisition system compiled by Labview was designed to make the measurement and control test bench more automated.