Hydraulic pump performance deterioration detection system

A hydraulic pump performance deterioration detection system comprising:

• a variable displacement hydraulic pump;
• a switching valve that is connected to the hydraulic pump by a pump line and to a hydraulic actuator by a supply/discharge line and that blocks the pump line causing the hydraulic actuator to not move;
• a regulator that changes a displacement of the hydraulic pump in accordance with a command current and that limits the displacement of the hydraulic pump to a limiting value when a delivery pressure of the hydraulic pump has become higher than a setting value;
• control circuitry that feeds the command current to the regulator, the control circuitry including a hardware processor;
• and
• a pressure sensor that measures the delivery pressure of the hydraulic pump,
• wherein with the hydraulic actuator not moving the control circuitry:
• feeds the command current to the regulator such that the displacement of the hydraulic pump is minimized,
• performs a performance check to determine whether or not performance of the hydraulic pump has deteriorated based on a current value of the command current and the delivery pressure of the hydraulic pump measured by the pressure sensor, and
• wherein the control circuitry further:
• changes the command current
• stores, as a determination-use current value, the current value of the command current when the delivery pressure of the hydraulic pump measured by the pressure sensor has become a threshold value;
• compares the stored determination-use current value with a prestored reference current value;
• and
• determines that the performance of the hydraulic pump has deteriorated in a case where the determination-use current value is greater than the reference current value by at least a setting value.

A hydraulic pump performance deterioration detection system comprising:

• a hydraulic cylinder that extends to press a workpiece;
• a hydraulic pump that is connected to the hydraulic cylinder by a pair of supply/discharge lines in a manner to form a closed circuit;
• an electric motor that drives the hydraulic pump;
• control circuitry that controls the electric motor, the control circuitry including a hardware processor;
• and
• a pressure sensor that measures a delivery pressure of the hydraulic pump when the hydraulic cylinder extends, wherein
• the control circuitry:
• while the hydraulic cylinder is pressing the workpiece, adjusts a rotation speed of the electric motor such that the delivery pressure of the hydraulic pump, which is measured by the pressure sensor, is a setting value;
• stores the adjusted rotation speed as a determination-use rotation speed;
• and
• compares the determination-use rotation speed that has been newly stored with a previously stored determination-use rotation speed to determine whether or not performance of the hydraulic pump has deteriorated.