The Effect Of The Variable Load On The Pressure Of The Hydraulic Cylinder In The Entrance Throttle Governing System

Used the entrance throttle governing system in which the hydraulic cylinder was the executive element as research object in this thesis, the experimental research about the effect of various step loads on the pressure of the hydraulic cylinder chamber without piston-rod when series-connecting throttle valve or governor valve on the entrance oil-line was made.Accorded to the experimental research, under different flow area of flow valve and different adjusted pressure of relief valve, conclusions that the regulation of the dynamic variety of P1(t) (the pressure on the hydraulic cylinder chamber without piston-rod) when exerted by step loads were as follows:When the throttle valve was series-connected on the entrance oil-line in the entrance throttle governing system:Under the same flow area and the same adjusted pressure Pp of relief valve, and at the same piston-rod working position, with the incremental quantity of step loads, the Mp(maximum overshot of pressure), ts(setting time) and N(number of oscillation during setting time) of P](t) all decreased, meanwhile, it's tr (rise time) and tp(time to peak) both increased;Under the same adjusted pressure of relief valve, and at the same piston-rod working position, applied by the same quantity of step loads, with the increase of flow area , the Mp, ts and N of P1(t) all decreased, meanwhile, it's tr and tp both increased.Under the same flow area, and at the same piston-rod working position, applied by the same quantity of step loads, with the increase of adjusted pressure of relief valve, the Mp, ts and N of P|(t) all increased, meanwhile, it's tr and tp both decreased.The maximum Mp of P1(t) is 52.3% when Ppis less than 2.4 MPa and the flow through the entrance oil-line is more than 1029 ml/min and the maximum Mp of P|(t) is 57.8% when Pp is less than 4.2 MPa and the flow through the entrance oil-line is more than 2029 ml/min.When the governing valve was series-connected on the entrance oil-line in the entrance throttle governing system, all of the regulation of the dynamic variety of P](t) with the system applied by step loads is similar with the regulation when throttle valve was series-connected on the system, and The maximum Mp of P|(t) is 51.3% when Ppis less than 2.4 MPa and the flow through the entrance oil-line is more than 473 ml/min and themaximum Mp of P1(t) is 73.8% when Pp is less than 4.2 MPa and the flow through the entrance oil-line is more than 530 ml/min.Through experimental research, the calculation diagram that the maximum overshot of pressure P1(t) Varied with the various step loads and the formula about hydraulic elements main parameter (rated pressure) were both made, and another method of selecting the hydraulic elements main parameter was given.This thesis also have constructed mathematic model based on the analytic method, which used the load F(s) as input and the pressure P(s) as output, Meanwhile, It have made theoretic analysis of time response as well as stability analysis. The theoretic analysis results were highly agreed with the experimental result.