Pumps – With condition responsive pumped fluid control – Pressure responsive relief or bypass valve
Patent
1999-06-30
2000-12-26
Freay, Charles G.
Pumps
With condition responsive pumped fluid control
Pressure responsive relief or bypass valve
417313, 417533, 367142, 188 726, 180 63, 180140, 91499, 73 492, F04B 4900
Patent
active
061649279
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for deaerating hydraulic power-assisted steering systems with oil expansion volumes.
Generic-type power-assisted steering systems are known in prior art, whereby a power steering pump supplies a pressure medium, typically hydraulic oil, via a servo steering valve to the chambers of a hydraulic steering gear. It is known on the one hand that so-called air accumulations occur in hydraulic systems, which can result in undesirable and partly unpleasant steering results. On the other hand, so-called oil expansion volumes are created in hydraulic systems, for example, if resonators are used. Air may develop in different ways, for example, through leaks, elimination from the pressure medium, and the like. Particularly if the oil expansion volumes, e.g., the resonator, have a dome in which air may collect because the dome points upward in mounted position, a corresponding amount of air will accumulate over time within the dome and cause significant interference due to foaming and will consequently increase pump wear.
There is thus a need to take measures to reduce the enclosed air quantities.
Based thereon, it is the object of the invention to define a method for reducing air pockets. A further object of the invention is to define a hydraulic power-assisted steering system with reduced air constituents that will not have the disadvantages caused by air pockets.
For the technical solution to this problem, the invention defines a method for deaerating hydraulic power-assisted steering systems with oil expansion volumes, whereby the upper volume area as seen in mounted condition is connected with a tank volume.
To solve this technical problem, the invention proposes a hydraulic power-assisted steering system with at least one oil expansion volume in the form of a resonator arranged on a hydraulic pump. The top area of this resonator in mounted position has a connection to a tank volume provided by a valve that projects directly into the tank and is used simultaneously as a deaeration and feeding valve.
This technical solution according to the invention makes it possible to remove the air accumulating within the dome to an open system. This open system is realized by a tank volume. Other embodiments are feasible and fall within the scope of the invention. For this purpose, the invention provides that the connection between the two volumes advantageously depends on operating parameters. A suitable operating parameter is the hydraulic pressure.
Thus, at a given hydraulic pressure, a connection is established such that the air accumulated in an expansion volume can be removed to an open system. The invention advantageously proposes to use a connection line. Particularly advantageously, this connection line is realized by a valve or is provided with a valve.
The invention provides a simple, low-cost method to prevent to a large extent the formation of air pockets.
Applying the method according to the invention to a hydraulic power-assisted steering system results in a novel power-assisted steering system with an oil expansion volume, the top area of which, as seen in mounted condition, is provided with a connection to an open system, preferably a tank volume.
The invention may be applied with particular advantage to a hydraulic power-assisted steering system with integrated resonator.
Particular advantages result in steering systems, in which a resonator is arranged directly on the hydraulic pump. The resonator is a volume element with a plurality of chambers, whereby the pressure pulsation of the hydraulic oil is reduced in the resonator. It is known to arrange such a resonator directly in an upper area of the hydraulic pump. A tank, typically a plastic component, surrounds both a part of the pump and the resonator.
Particularly advantageously, a valve is disposed in the upper area of the resonator or of an expansion volume. According to a particularly advantageous proposal of the invention, this valve opens as a function of pressure.
According to an advantageous proposal of the
REFERENCES:
patent: 3893528 (1975-07-01), Rehfeld
patent: 4527654 (1985-07-01), Shibahata et al.
patent: 4782689 (1988-11-01), DeRome
patent: 4888980 (1989-12-01), DeRome
patent: 5042832 (1991-08-01), Takahashi et al.
patent: 5081908 (1992-01-01), McBeth et al.
patent: 5360322 (1994-11-01), Henein et al.
patent: 5407033 (1995-04-01), Weiler et al.
patent: 5508975 (1996-04-01), Walter
patent: 5769608 (1998-06-01), Seale
patent: 6085792 (2000-07-01), Cooper et al.
Brown Steven
Freay Charles G.
Marzocchi Pompe S.r.l.
TRW Fahrwerksysteme GmbH & Co. KG
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