Pumps – One fluid pumped by contact or entrainment with another – Diverse pumps
Patent
1994-09-30
1996-03-05
Bertsch, Richard A.
Pumps
One fluid pumped by contact or entrainment with another
Diverse pumps
417189, 417198, 239600, F04B 2308, B05B 100
Patent
active
054961521
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This is a national phase of PCT/EP 92/02584 filed 13 Oct. 1992 and based, in turn, on German national application P41 38 516.0 of 23 Nov. 1991.
The invention relates to a pump which comprises a delivery system in a pump hosing, a fluid supply channel extending in the pump housing, and a control valve between suction and pressure regions of the pump. An injector actuatable by fluid under high pressure transports fluid from the supply channel or passage to the suction region of the delivery system.
BACKGROUND OF THE INVENTION
Pumps of the aforedescribed type are used for instance in power-assisted steering systems and feed a special fluid, e.g. an oil, for assistance of the steering forces exerted on the steering wheel of a motor vehicle. Preferably these pumps are vane pumps, which suck oil from a supply outside the pump, such as a reservoir. Such pumps are equipped with a valve, i.e. a flow control valve, through which the oil can be directed from the, high pressure region to the suction region of the pump. Starting from a certain rotational speed of the pump and at firmly established flow rates the valve opens an escape bore, wherein the oil under high pressure can escape. The bypassed oil reaches the intake space of the delivery system. Frequently the pump is not completely filled with the hydraulic oil. Moreover the channels through which the oil flows can be damaged due to cavitation.
OBJECT OF THE INVENTION
From U.S. Pat. No. 2,724,335 a pump for delivering a fluid is known wherein an injector is actuatable by fluid under high pressure and through this injector fluid is delivered from the supply channel to the suction region of the delivery system. It is a disadvantage that the injector, particularly during pressure fluctuations of the fluid, can not always insure that a sufficient quantity of fluid can be delivered to the suction region of the delivery system.
Furthermore arrangement of injectors are known also from printed applications FR-A-2 074 206 and FR-A-2 443 598, wherein by means of a fluid exiting a reservoir under high pressure a further fluid can be delivered to the suction area of delivery system. Here too it is disadvantageous that in case of pressure fluctuations an insufficient amount of fluid is directed towards the suction area.
Therefore with the known injector arrangements it is practically impossible to insure a cavitation-free operation in presence of variable flow rates of the delivery system.
OBJECT OF THE INVENTION
It is therefore the object of the invention to enable a cavitation-free operation of the pump for the entire range of rotational speeds, whereby a sufficient filling of the pump with hydraulic oil is insured.
SUMMARY OF THE INVENTION
This object is attained in a pump of the type described, but wherein the body of the injector is surrounded by an annular channel which is connected with the supply channel.
By means of the injector which is actuated by a fluid coming from an area under high pressure and feeds oil from the supply channel to the suction region of the delivery system, a sufficient filling of the suction region is insured for all stages of the opeation. Therefore based on the good supply of the suction region with hydraulic oil cavitation damage can be avoided.
A preferred embodiment of the pump has an inlet zone of the injector located close to the outlet of the control valve, which optionally allows a fluid under high pressure to empty into an escape bore. The energy-rich fluid is captured by the injector, so that damage inside the pump housing is avoided. Based on the fact that the opening of the injector into the supply channel is arranged immediately ahead of the suction region of the delivery system, an optimal guidance of the oncoming fluid is insured, so that even at a high flow rate of the pump cavitation can be avoided.
The basic body of the injector can be surrounded by an annular channel which is connected to the supply channel. Oil coming from an oil supply located outside the pump, for insta
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Heise Manfred
Lauth Hans J.
Nguyen Van D.
Stammler Erwin
Bertsch Richard A.
Dubno Herbert
Kim Ted
Luk Farhzeug-Hydraulik GmbH & Co. KG
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