Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2001-03-05
2003-09-02
Rivell, John (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C091S37500R
Reexamination Certificate
active
06612336
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rotary-disk valve for motor vehicle power steering systems.
BACKGROUND INFORMATION
The rotary-disk valve according to the present invention contains two valve elements, which are movable coaxially into one another and are turnable with respect to one another to a limited degree in order to obtain a control path. A first valve element, which is connected non-rotatably to a valve inlet element, is connected to a valve outlet element via a torsion bar spring and via a mechanical drive in the form of a dead travel coupling. A second valve element is connected non-rotatably to a valve outlet element. The radially external valve element has internal longitudinal control grooves and the radially internal valve element has external longitudinal control grooves, which interact with one another in order to control a pressure medium to and from two working chambers of the servo motor and to a return connection for a pressure medium container.
Such a rotary disk valve is described, for example, in German Published Patent Application No. 1 913 837. In this rotary-disk valve, the pressure medium returns to the pressure medium container directly from the return grooves to a return connection. For this purpose, the return grooves are open to one side. This results in an interrupted bearing point on the circumference between the two valve elements, thereby resulting in certain disadvantages. Such a valve may tend to seize, which in turn may lead to undesirable noises and a poor steering feel.
A further rotary disk valve is described in European Published Patent Application 0 171 247. In this rotary disk valve, the return grooves are closed on both sides in their axial length. Return from the return grooves to the return connection occurs through an inner space in the radially internal valve element and via a diagonal hole in the radially internal valve element. Such diagonal holes are complicated and expensive to manufacture. In this radial disk valve, the radially internal valve element is supported on the torsion bar spring by a sliding bearing.
International Published Patent Application No. WO 87/04678 describes a rotary disk valve having a rotary disk, a control bushing surrounding a rotary disk and a working shaft, which is connectable with a pinion that engages with a gear rack. A pressure medium flow delivered by a pump is introduced into a circular groove of the valve housing surrounding these parts. The distribution of the pressure medium flow occurs according to the position of the control grooves, control edges and control holes in the rotary disk and the control bushing in hydraulic lines that lead to a working cylinder. A return line, which is supplied via a gap between the inner wall of the bearing parts and the torsion bar, is used for the return of the pressure medium.
One object of the present invention is to provide a rotary disk valve which can be produced simply and inexpensively. In addition, the return may be made without significant pressure losses, and the valve may be operated with as little friction and seizing as possible.
SUMMARY
The above and other beneficial objects of the present invention are achieved by providing a rotary disk valve which the rotary disk valve includes a return from the longitudinal grooves of the radially internal valve element controlling the return to the return connection through a roller bearing.
In a first embodiment, the roller bearing is one of the roller bearings with which the first valve element is supported in the other valve element.
In a second embodiment, the longitudinal control grooves of the radially internal valve element controlling the return connection are connected to an inner space of the radially internal valve element, and the torsion bar spring is supported in the inner space of the radially internal valve element via a roller bearing. The return from the inner space of the radially internal valve element to the return connection occurs through the roller bearing and the dead travel coupling. If the roller bearing is designed as a needle bearing, this bearing may be equipped with a needle cage, which has a cross-section favorable to flow and is provided with flow openings that permit the returning pressure medium to flow without a significant pressure drop. In addition, such a bearing may be installed under pre-stress, so that support of the internal valve element can be achieved without play together with a favorable rolling friction at the same time. Also seizing of the valve and the appearance of noises and abrupt changes in torque connected therewith is avoided.
If the longitudinal control grooves controlling the return connection of the radially internal valve element are connected to an internal space of the radially internal valve element, the torsion bar spring is supported in the internal area of the radially internal valve element via a roller bearing and return from the inner space of the radially internal valve element to the return connection occur through the roller bearing and through the dead travel coupling.
REFERENCES:
patent: 4137989 (1979-02-01), Rehfeld
patent: 4285266 (1981-08-01), Elser
patent: 4290452 (1981-09-01), Takahashi et al.
patent: 4905782 (1990-03-01), Rieger et al.
patent: 5086687 (1992-02-01), Elser et al.
patent: 5517899 (1996-05-01), Bohner
patent: 5538096 (1996-07-01), Breitweg
patent: 11 01 186 (1961-03-01), None
patent: 1 913 837 (1974-03-01), None
patent: 41 39 506 (1992-06-01), None
patent: 41 38 885 (1993-06-01), None
patent: 32 42 445 (1994-06-01), None
patent: 196 44 511 (1998-04-01), None
patent: 0 171 247 (1990-09-01), None
patent: 87/04678 (1987-08-01), None
patent: 94/00329 (1994-01-01), None
Ertle Peter
Hafermalz Jens-Uwe
Urban Karl-Heinz
Kenyon & Kenyon
Rivell John
ZF Lenksysteme GmbH
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