Motor vehicles – Steering gear – With fluid power assist
Patent
1994-09-30
1996-07-23
Culbreth, Eric D.
Motor vehicles
Steering gear
With fluid power assist
180441, 180428, 91375A, B62D 5083
Patent
active
055380964
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a rotary slide valve for auxiliary power steering systems in motor vehicles. The rotary slide valve contains two valve elements that are arranged so that they are coaxially movable inside each other and so that they can be turned by a maximum of the turning distance of a dead-travel clutch with respect to each other. The first valve element is connected in a non-rotary manner with a valve inlet member and the second valve element is connected with a valve outlet member via a dead-travel clutch. The first valve element is connected with the valve outlet member via a torsion rod. Both valve elements have longitudinal control grooves that, at least partly, are limited in terms of their axial length and that cooperate directly with each other for the control of a pressure medium to and from two working chambers of a servomotor.
2. Description of the Prior Art
Such a rotary slide valve is known, for example, from U.S. Pat. No. 3,746,045. Like other known rotary slide valves, the known rotary slide valve contains a rotary slide that is guided in an axial borehole of a control sleeve. The rotary valve is connected with a valve outlet member via a torsion rod. Besides, the rotary slide is connected with the valve outlet member via a dead-travel clutch. Such a dead-travel clutch limits the relative turning of the two valve elements toward each other and creates a mechanical stop of the valve after the turning path of the dead-travel clutch has been used up. In case the auxiliary power support fails, it must be possible to transmit the entire mechanical steering force via this mechanical stop. These operating conditions create the dimensions of the dead-travel clutch and thus of the two valve elements and the entire rotary slide valve. The outside dimensions of the rotary slide valve, which are determined by the possible high mechanical stresses, are frequently too great for the limited installation space in a motor vehicle.
The task of the invention, therefore, is to reduce the dimensions of a known rotary slide valve and to improve the steering qualities of the auxiliary power steering.
SUMMARY OF THE INVENTION
This problem is solved by the rotary slide valve of the present invention. The solution consists in the fact that the rotary slide is not the internal but rather the external valve element so that the control sleeve is guided as a second valve element inside the rotary slide in an axial borehole. This arrangement is achieved, in particular, in that the control sleeve is made by means of a non-cutting production process. The control sleeve can be made with its control grooves and control edges ready for use by means of cold shaping. The control sleeve can be made of sheet metal with very thin walls with the help of the non-cutting production process. In spite of the thin wall, one gets a very stable control sleeve on account of the favorable material flow; the outside dimensions of that control sleeve are considerably smaller than comparable, hitherto known parts. The reduction of the valve diameters results in essentially less valve friction and thus an improved steering sensation.
The dead-travel clutch is formed by an internal gearing of the rotary slide and by an external gearing of the valve outlet member and thus rests on a relatively large diameter that ensures reliable catching even if the auxiliary power support should fail. Because the rotary slide is guided with its external circumferential surface directly in the valve housing and therefore must, on its outer circumferential surface, reveal the required ring grooves for the connections of the servopump, the tank, and the servomotor, it is possible to arrange sealing rings between these ring grooves. At least two of the customarily present four sealing rings are impacted by the working pressure and are therefore pressed against the borehole of the valve housing and thus have an advantageous attenuating effect.
If the rotary slide is positioned via two roller bearin
REFERENCES:
patent: 3707167 (1972-12-01), Colleti
patent: 3746045 (1973-07-01), Bunker et al.
patent: 3807456 (1974-04-01), Colleti
patent: 4063490 (1977-12-01), Duffy
patent: 4335749 (1982-06-01), Walter
patent: 4373598 (1983-02-01), Elser
patent: 4378030 (1983-03-01), Duffy
patent: 4465101 (1984-08-01), Hasegawa
patent: 4516471 (1985-05-01), Duffy
patent: 4623839 (1986-11-01), Rayner
patent: 4742883 (1988-05-01), Duffy
patent: 4759420 (1988-07-01), Schipper, Jr. et al.
patent: 4768604 (1988-09-01), Schipper
patent: 4788877 (1988-12-01), Robinson et al.
patent: 4796715 (1989-01-01), Futaba et al.
patent: 4905782 (1990-03-01), Rieger et al.
patent: 5029513 (1991-07-01), Duffy
patent: 5069301 (1991-12-01), Adams
patent: 5189941 (1993-03-01), Roethlisberger et al.
patent: 5392875 (1995-02-01), Duffy
Culbreth Eric D.
Zeender F.
ZF Friedrichshafen AG
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