Automatic neutral point detecting system for hydraulic pump

摘要

An automatic neutral point detecting system for a hydraulic pump equipped with a displacement varying device capable of shifting both in a (+) direction and in a (-) direction and connected to at least one hydraulic actuator to form a hydraulic circuit to drive the hydraulic actuator. The system includes pressure sensors for sensing the port pressures of the hydraulic pump, a shifting detector for detecting the shifting of the displacement varying device, a closing device for closing the hydraulic circuit and blocking the flow of a hydraulic fluid, a start switch for giving a command to start detection of the neutral point of the hydraulic pump, and a control unit for detecting the neutral point of the hydraulic pump. The control unit includes means responsive to the command given by the start switch for giving a command to activate the closing device, data collecting means for causing the displacement varying device to shift at least once in the (+) direction and in the (-) direction based on information from the pressure sensors and the shifting detector until the port pressure on the discharge side of the hydraulic pump becomes at least substantially equal to the same predetermined pressure set beforehand for each shifting direction and collecting data on the values of the shifting of the displacement varying device when the port pressure on the discharge side of the hydraulic pump becomes substantially equal to the predetermined pressure, and means for producing a mean of the values collected by the data collecting means.