Variable displacement pump
AssigneeHitachi Astemo, Ltd.
InventorShigeyuki Miyazawa
Life of this patent
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Abstract
A variable displacement pump according to the present invention is notably configured such that the opening area of a variable metering orifice (MO) is variably controlled by a second control valve (6) as a spool valve having a second spool valve body (61). According to this type of the second control valve (6), a larger amount of movement (stroke movement) of the second spool valve body (61) can be ensured. Consequently, the opening area of the variable metering orifice (MO) can be controlled without being restricted by a range of variation in a proper discharge amount based on an amount of movement of a cam ring (2), thereby achieving sufficient energy conservation of the pump.
Claims14
A variable displacement pump, comprising:
- a pump housing including a pump element accommodation part thereinside;
- a cam ring formed in an annular shape and provided inside the pump element accommodation part;
- a rotor and a plurality of vanes configured to carry out suction and discharge of hydraulic fluid, wherein the rotor is rotatably provided inside the cam ring, and wherein the plurality of vanes are accommodated on an outer circumferential side of the rotor so as to retractably move through the outer circumferential side in a radial direction, and wherein a plurality of pump chambers, each of which is partitioned by a pair of vanes of the plurality of vanes arranged adjacent to each other, are formed between the cam ring and the rotor;
- a first fluid pressure chamber and a second fluid pressure chamber that are a pair of spaces provided between the pump element accommodation part and the cam ring, wherein a pressure within the first fluid pressure chamber moves the cam ring about a pin member in the pump element accommodation part to vary a discharge amount from a pump formed of the rotor and the vanes;
- a suction port provided to the pump housing and opened to a suction region formed between the cam ring and the rotor;
- a discharge port provided to the pump housing and opened to a discharge region formed between the cam ring and the rotor;
- a suction passage provided to the pump housing and used for supplying the hydraulic fluid to the suction port;
- a discharge passage provided to the pump housing and used for supplying the hydraulic fluid discharged from the discharge port to an outside of the pump housing;
- a variable metering orifice that is a throttle portion provided to the discharge passage;
- a first control valve controlled based on a pressure within the discharge region of the pump chambers and a pressure of a downstream side of the variable metering orifice, and which is configured to control a pressure to be introduced into the first fluid pressure chamber with a pressure on the variable metering orifice and a pressure of the suction passage;
- and
- a second control valve configured to variably control an opening area of the variable metering orifice, and provided with a valve body controlled based on a pressure of the second fluid pressure chamber or the pressure of the suction passage and a pressure of the first fluid pressure chamber.
Dependencies are inferred from the claim text.