Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2000-07-24
2001-11-13
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S129070, C251S325000, C137S625650, C137S625680, C335S255000, C335S262000
Reexamination Certificate
active
06315268
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a solenoid, in particular, for actuating a hydraulic valve of a motor vehicle, that comprises a pole core delimiting an armature chamber, wherein an armature is slidingly movable in the armature chamber and wherein a minimal axial spacing of the armature relative to the pole core is determined by an anti-stick disc. The solenoid further comprises an armature piston that is received in a central receptacle of the armature and extends through a central bore of the pole core, preferably with formation of a radial gap, wherein the armature piston is preferably made of nonmagnetic material and is used to actuate a valve member when acted on by the armature.
2. Description of the Related Art
Such a solenoid is, for example, known from the German patent document 197 17 445 A1 or the German patent document 195 04 185 A1. In these solenoids the armature piston is produced of solid rod material that has nonmagnetic properties. Between the facing end faces of the armature and the pole core an anti-stick disc is arranged which surrounds the armature piston and whose thickness defines a minimal axial air gap between the armature and the pole core. The anti-stick disc is a separate part and must be threaded onto the armature piston and mounted together with the armature and the armature piston, the latter being pressed into a blind bore of the armature. Overall, the manufacture of the individual parts and their assembly are complex and expensive.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to develop a solenoid of the aforementioned kind such that it can be produced in a cost-effective manner.
In accordance with the present invention, this is achieved in that for a solenoid of the aforementioned kind the armature piston is produced as a tubular member from a planar sheet metal and comprises an anti-stick disc as a monolithic part of the tubular member wherein the anti-stick disc is formed from the sheet metal by bending parts of the sheet metal material radially outwardly. According to the invention, the armature piston and the anti-stick disc thus are formed as a monolithic part from of a planar sheet metal. In principle, this manufacture can be realized by a stamped-bent part or a deepdrawn part and, especially for large production numbers, can be highly automated. By providing a monolithic part, the assembly expenditure is reduced significantly. Moreover, the process safety is increased because the possibilities of assembly errors are reduced. Overall, the solenoid according to the invention can be produced more cost-effectively and with excellent quality.
According to a preferred embodiment, the armature piston is a stamped-bent part rolled to a tubular member from a planar sheet metal piece. In the vicinity of the armature several metal strips are cut out of the piston wall of the armature piston and bent radially outwardly to form the anti-stick disc while forming openings in the piston wall of the armature piston.
According to another embodiment of the invention, the metal strips, for increasing the thickness of the formed anti-stick disc, are folded over at least once.
Preferably, the individual metal strips and openings are distributed with identical angular spacing about the armature piston. Especially preferred is an arrangement with three metal strips and three corresponding openings having a respective spacing of 120° from one another.
In a preferred embodiment of the invention, the armature piston has on its end face facing away from the armature, or in the vicinity of this end face, an additional opening.
Expediently, the end face of the armature piston facing away from the armature has sheet metal material bent inwardly.
Advantageously, several sheet metal segments of the sheet metal are bent radially inwardly at the end face and leave open a central opening.
When producing the armature piston as a deepdrawn part, the sheet metal material for forming the armature piston is upended in the area of the anti-stick disc and in this way the anti-stick disc is formed. However, when a radial gap is provided between the armature piston arid the central bore of the pole core, which must be bridged by the anti-stick disc, the anti-stick disc must be provided, if needed, with such a great outer diameter that difficulties will arise during the deepdrawing process. When the armature piston is a stamped-bent part, the anti-stick disc is preferably produced in that several metal strips are cut out of the piston wall of the armature piston and are bent radially outwardly in order to produce the anti-stick disc, while leaving openings in the piston wall. In particular, the resulting openings are positioned outside of the armature so that they can be used for oil exchange between the two partial chambers of the armature chamber on both ends of the armature and between the armature chamber and a space in front of the pole core. The formation of the anti-stick disc from individual metal strips has furthermore the advantage that the anti-stick disc will not completely close off a radial gap between the armature piston and the pole core, even though it rests against the inner wall of the pole core. This is different for an uninterrupted anti-stick disc.
A relatively thin sheet metal material is preferably used because it can be easily processed. It is in this connection possible to produce an anti-stick disc which has a thickness that is greater than the thickness of the sheet metal material by folding over the sheet metal strips at least once.
It is especially expedient when the armature piston has an additional opening on the end face facing away from the armature, or in the vicinity of this end face. Via this additional opening, an oil exchange, that is independent of the radial gap between the pole core and the armature piston, can take place between the hollow spaces of the solenoid and a valve connected thereto in order to compensate volume changes resulting from the move men t of the armature and the armature piston or in order to compensate temperature-caused volume changes of the hydraulic oil present within the hollow spaces of the solenoid.
The invention also concerns a hydraulic valve with a hollow piston which is positioned in a valve bore adjoining the pole core. The hollow piston has an end wall delimiting a hollow space in the hollow piston and rests in one end position with the end wall, which can be loaded by the armature piston, against the pole core. In accordance with the present invention, an open connection, i.e., fluid communication, between the hollow spaces of the valve and the hollow spaces of the solenoid can be provided, even when the hollow piston of the valve rests against the pole core, by providing in the end face of the hollow piston a connecting bore which is open toward the hollow chamber and, in the end position of the hollow piston in which the end wall rests against the pole core, this connecting bore is open to the central bore of the pole core. In an especially preferred embodiment, the connecting bore coincides with, or is concentric to, the axis of the hollow piston and is open to the central opening in the end face of the armature piston when the end wall of the hollow piston rests against the pole core. In this way an oil exchange between the valve and the solenoid can take place through the end face of the armature piston.
REFERENCES:
patent: 3606241 (1971-09-01), Bornholdt
patent: 3726315 (1973-04-01), Sheppard
patent: 3896405 (1975-07-01), Pauli
patent: 3932826 (1976-01-01), Read, Jr.
patent: 4563664 (1986-01-01), Chin et al.
patent: 4835426 (1989-05-01), Henville
patent: 4838954 (1989-06-01), Perach
patent: 4917352 (1990-04-01), Hauet et al.
patent: 5402093 (1995-03-01), Gibas et al.
patent: 5856771 (1999-01-01), Nippert
patent: 5871201 (1999-02-01), Cornea et al.
patent: 5967487 (1999-10-01), Cook et al.
patent: 12 49 043 (1967-08-01), None
patent: 42 10 740 C2 (1993-10-01), None
patent: 195 04 185 A1 (1996-08-01), None
patent: 197 17 4
Cornea Marius
Leutwein Hans-Ulrich
Lippert Lorenz
Huckett Gudrun E.
Hydraulik-Ring GmbH
Keasel Eric
Shaver Kevin
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