| 摘要 |
This hydraulic device for driving an oil well pump is provided, as a pump main body within a single housing by means of a single unit structure, with at least a bidirectional variable-capacity piston pump, a discharge quantity detection unit, a discharge pressure detection unit, and a magnetic proportional control valve. Within the pump main body are provided: a connection section that is provided to the housing side surface and to which the pump discharge duct of an external pilot hydraulic circuit is connected; and a second pilot duct that leads an external pilot pressure from the connection section to a pilot duct between the magnetic proportional control valve and the discharge duct of the piston pump. A means that mechanically cuts off the supply of the external pilot pressure at the point in time when the discharge pressure of the piston pump becomes no greater than a preset pressure is further provided on the second pilot duct. As a result, it is possible, by means of a simple configuration that does not lead to increased cost and that does not rely on electrical control, to provide a hydraulic device that is for driving an oil well pump and that can avoid the occurrence of cavitation even if a control system halts. |
