Hydraulic pump performance deterioration detection system

A hydraulic pump performance deterioration detection system comprising:

• a hydraulic pump that is driven by a prime mover and that supplies a hydraulic liquid to a hydraulic actuator to move the hydraulic actuator;
• a switching valve located on a passage through which the hydraulic liquid delivered from the hydraulic pump flows, the switching valve being switchable between an open position in which the switching valve opens the passage and a particular restrictive position in which an opening degree of the switching valve is within a range of 1 to 70%;
• control circuitry, including a hardware processor, configured to change a rotation speed of the prime mover;
• and
• a pressure sensor that measures a delivery pressure of the hydraulic pump at a position upstream of the switching valve, wherein
• the control circuitry switches the switching valve to the particular restrictive position,
• when the hydraulic actuator is not moving, in a state where the switching valve is switched to the particular restrictive position, the control circuitry determines whether or not performance of the hydraulic pump has deteriorated based on the rotation speed of the prime mover and the delivery pressure of the hydraulic pump measured by the pressure sensor, and
• in the state where the switching valve is switched to the particular restrictive position, the control circuitry:
• changes the rotation speed of the prime mover,
• stores, as a determination-use rotation speed, the rotation speed of the prime mover when the delivery pressure of the hydraulic pump measured by the pressure sensor has become a threshold value,
• compares the stored determination-use rotation speed with a prestored reference rotation speed, and
• determines that the performance of the hydraulic pump has deteriorated in a case where the determination-use rotation speed is greater than the reference rotation speed by at least a setting value.

A hydraulic pump performance deterioration detection system comprising:

• a hydraulic pump that is driven by a prime mover and that supplies a hydraulic liquid to a hydraulic actuator to move the hydraulic actuator;
• a switching valve located on a passage through which the hydraulic liquid delivered from the hydraulic pump flows, the switching valve being switchable between an open position in which the switching valve opens the passage and a particular restrictive position in which an opening degree of the switching valve is within a range of 1 to 70%, the opening degree of the switching valve in the particular restrictive position being a predetermined value;
• control circuitry, including a hardware processor, configured to change a rotation speed of the prime mover;
• and
• a pressure sensor that measures a delivery pressure of the hydraulic pump at a position upstream of the switching valve, wherein
• the control circuitry switches the switching valve to the particular restrictive position,
• when the hydraulic actuator is not moving, in a state where the switching valve is switched to the particular restrictive position, the control circuitry determines whether or not performance of the hydraulic pump has deteriorated based on the rotation speed of the prime mover and the delivery pressure of the hydraulic pump measured by the pressure sensor,
• the hydraulic pump supplies the hydraulic liquid to the hydraulic actuator via a control valve,
• the passage is an unloading passage branched off from a supply passage that connects the hydraulic pump to the control valve,
• the switching valve is an unloading valve whose opening degree is arbitrarily changeable within a range of 0 to 100%, and
• the opening degree of the switching valve in the open position is 100%, the opening degree of the switching valve in a closed position is 0%, and the closed position is a position in which the switching valve, which is the unloading valve, blocks the unloading passage.