Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Patent
1998-12-14
2000-05-09
Hepperle, Stephen M.
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
13711507, 13711515, 13711519, B62D 507, F16K 326
Patent
active
060589620
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a flow control valve for a hydraulic pump suitable for use as a hydraulic power source for a power steering device of a vehicle.
BACKGROUND ART
A power steering device equipped with a conventional flow control valve for a hydraulic pump is disclosed in Japanese Patent Application No. 115052/1995 filed by the assignee.
FIG. 7(A) shows a hydraulic pump in which a flow control valve FV disclosed in the Japanese application is integrally incorporated. A vane pump VP is used as the hydraulic pump.
The vane pump VP includes a housing H constructed of a pump body 10 and a cover 11. The housing H is formed with a shaft hole 12, in which a shaft 14 is rotatably supported through a bearing 13 arranged in the shaft hole 12. The shaft 14 functions as a drive shaft for a rotor 15 arranged in the pump body 10. The rotor 15 has a plurality of vanes 16 radially incorporated therein.
Also, the rotor 15 is mounted thereon with a cam ring 17 as shown in FIG. 7(B) which is viewed along line X--X of FIG. 7(A). The cam ring 17 has an inner surface formed into an elliptic shape. Driving of the shaft 14 permits rotation of the rotor 15, during which the vanes 16 are accessed to the inner surface of the cam ring 17. Thus, the vanes 16 are rotated while being intimately contacted with the cam ring 17 and permit chambers independent from each other to be defined therebetween.
When the chambers thus defined each are subject to a contraction stroke, hydraulic oil or fluid is discharged from a discharge port; whereas when each of the chambers is subject to an expansion stroke, hydraulic fluid is sucked thereinto.
The rotor 15 and cam ring 17 are commonly provided on a side surface thereof with a side plate 18. This results in a high-pressure chamber 19 being defined on a rear surface side of the side plate 18, so that a pump discharge pressure may be guided to the high-pressure chamber 19. A pressure of hydraulic fluid in the high-pressure chamber 19 forces the side plate 18 against the rotor 15 to keep loading balance.
The flow control valve VP, which will be described hereinafter, is arranged in a manner to be integral with the pump body 10 of the vane pump VP, so that a body of the flow control valve VP may also act as the body 10 of the vane pump VP.
The shaft 14 of the vane pump VP is connected to an engine (not shown), so that starting of the engine permits rotation of the rotor 15 connected to the shaft 14. Thus, an increase in rotational speed of the engine leads to an increase in fluid discharge rate at which hydraulic fluid is discharged from the vane pump VP.
The hydraulic fluid thus discharged from the vane pump VP, as shown in FIGS. 4 to 6, is guided through a pump port 4 to a pressure chamber 8a of the flow control valve PV and fed from an actuator port 20a to a power steering circuit PS through a feed passage.
At this time, such flowing of the hydraulic fluid discharged results in a pressure difference occurring between both sides of a variable constriction 3 arranged in the course or middle of the feed passage. A pressure on an upstream side acts on a left end surface of a spool 7 positioned on a side of the pressure chamber 8a and a pressure on a downstream side acts on a right end surface of the spool positioned on a side of a pilot chamber 8b through a pilot passage 29.
However, the spool 7 is not permitted to be moved in a right-hand direction unless thrust obtained by multiplying the pressure difference between both sides of the variable constriction 3 by a pressure receiving area of the spool 7 exceeds initial load of a spring 9 or unless a predetermined fluid discharge rate of the pump is obtained, resulting in a pump port 4 and a drain port 5 being kept isolated from each other. Therefore, all hydraulic fluid discharged from the pump is fed to the power steering circuit PS (an interval a of a characteristic line K shown in FIG. 4(B)).
When a rotational speed of the engine is increased to increase a fluid discharge rate, resulting in the pressure difference between bo
REFERENCES:
patent: 2642887 (1953-06-01), Renick
patent: 2696828 (1954-12-01), Husing
patent: 4311161 (1982-01-01), Narumi et al.
patent: 5513672 (1996-05-01), Nguyen et al.
Hayashi Masumi
Hayashi Tetsuji
Nagasaka Ryoichi
Hepperle Stephen M.
Kayaba Kogyo Co., Ltd.
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