Oil-well-pump driving hydraulic system
AssigneeYuken Kogyo Kabushiki Kaisha
InventorsHirokazu Hiraide, Akihiro Hayashi
Life of this patent
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Abstract
In an oil-well-pump driving hydraulic system capable of avoiding occurrence of cavitation, at least a bidirectional variable displacement piston pump, a discharge rate detection portion, a discharge pressure detection portion, and a proportional solenoid control valve are contained as a single unit structure in a same housing as a pump body. The pump body includes: a connection portion provided on a side surface of the housing and to which a pump discharge passage of an external pilot hydraulic circuit is connected; and a second pilot passage that introduces an external pilot pressure from the connection portion to a pilot passage between the discharge passage of the piston pump and the proportional solenoid control valve.
Claims2
An oil-well-pump driving hydraulic system comprising:
- a bidirectional variable displacement piston pump that is rotationally driven by an external driving source and that displaces variable elements to control a discharge rate by pilot control using an autogenous pressure of part of a discharge pressure of the pump against a spring force to make the discharge rate variable;
- a discharge rate detection portion that detects the discharge rate of the piston pump and outputs a corresponding detection signal;
- a discharge pressure detection portion that detects the discharge pressure of the piston pump and outputs a corresponding detection signal;
- a control amplifier that outputs an output signal responsive to a difference between an external flow rate setting signal and the detection signal from the discharge rate detection portion or an output signal controlled responsive to a difference between an external pressure setting signal and the detection signal from the discharge pressure detection portion;
- a proportional solenoid control valve that controls a pump discharge rate by proportionally adjusting an opening of a communication portion between a pressure reception portion of one of the variable elements and a pump discharge port in response to an input signal from the control amplifier to control a displacement of the one of the variable elements;
- and
- an external pilot hydraulic circuit that introduces a discharge pressure from an external pump as a pilot control pressure,
- wherein at least the bidirectional variable displacement piston pump, the discharge rate detection portion, the discharge pressure detection portion, and the proportional solenoid control valve are provided as a single unit structure in a same housing as a pump body,
- wherein the pump body includes:
- a connection portion which is provided on a side surface of the housing and to which a pump discharge passage of the external pilot hydraulic circuit is connected;
- and
- a second pilot passage that introduces an external pilot pressure from the connection portion to a pilot passage between the discharge passage of the piston pump and the proportional solenoid control valve, and
- wherein a pilot operation check valve that mechanically cuts off supply of the external pilot pressure when the discharge pressure of the piston pump is under a predetermined pressure is provided on the second pilot passage, the pilot operation check valve using part of the discharge pressure of the piston pump as a pilot pressure.
Dependencies are inferred from the claim text.