Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1994-08-15
1995-12-19
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
25112915, B60T 836
Patent
active
054763134
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to electromagnetic valves and more particularly relates to electromagnetic valves for use in hydraulic brake systems with slip control.
BACKGROUND OF THE INVENTION
In the electromagnetic valve described in patent application No. P 40 28 447.6, it has become evident that the pressure relief valve function can be impaired if exact tolerances are not maintained in the valve needle guide of the magnet armature, due to the large frictional forces developed along the long valve needle guide of the magnet armature. As a further disadvantage, looseness may develop distance between the valve closing member and the valve seat due to inaccuracies or to wear.
It is, therefore, the object of the present invention to develop further an electromagnetic valve that avoids the above-mentioned disadvantages. Such a valve includes a precise, easily adjustable valve needle guide featuring minimum friction which guarantees a dependable closure of the valve needle.
SUMMARY OF THE INVENTION
According to one aspect, the valve of the present invention includes a stepped bore that extends over nearly the entire length of the magnet armature and in which configuration an end range within the magnet armature encircling the valve needle in an almost disc-shaped manner guides the valve needle. In the closing position of the valve the first stop being lifted off from the shoulder of the step of the bore by a defined axial distance, contrasting the effect of the compression spring.
The invention is, thus, based on the concept of creating a valve guide having as little friction as possible in the magnet armature and to apply adjustable bearing bushings which are introduced into the magnet armature separately.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the cross section of an electromagnetic valve in the unactuated (lefthand view of the valve) and in the actuated switching position of the valve (righthand view of the valve).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now referring to FIG. 1, magnet core 13 is retained within the valve housing 15 by caulking with the relatively thin-wall, drawn valve dome 14. The magnet coil 16 which is slid over the valve dome 14 being fastened by means of a locking ring 18 which is abutted against the coil housing 17 and against the valve dome 14.
In the lefthand illustration in FIG. 1 the valve needle 1 which is guided in the stepped bore 8 of the magnet armature 2 is in the non-energized normal position in which the valve permits of a free passage of the hydraulic pressure agent, so that through the annular slot between the valve seat 3 and the valve needle 1 an opening exists between the first and the second hydraulic pressure agent ducts 11, 12. Ducts 11, 12 are preferably in communication with a slip-controlled wheel brake.
Return spring 4 which is clamped in between the magnet core 13 and the magnet armature 2 lifts the valve needle 1 from the valve seat 3 when the valve coil 16 is in the electromagnetically non-energized normal position. A second compression spring 5 which is positioned in the coaxial stepped bore 8 of the magnet armature 2 and which takes support at a (second) stop 7 being fixed within the magnet armature by a pressing operation maintains the valve needle in the normal position shown in the illustration on the left as seen from the center line of the valve. Furthermore, between the front face of the magnet armature 2 and that of the magnet core 13 a non-ferromagnetic disc 10 is disposed which prevents the undesirable and generally known "sticking" of the magnet armature 2 to the magnet core 13.
As arranged to the right of the centre line of the valve, FIG. 1 moreover shows the movable valve components in the electromagnetically energized position, which will now be described.
MODE OF FUNCTIONING
As a result of the actuating force caused by the magnet coil 16 being energized by the supply of electric current, the valve needle 1 will close the valve seat 3. The valve is designed such that when needle 1 is seated against
REFERENCES:
patent: 4666125 (1987-05-01), Marts et al.
patent: 4898434 (1990-02-01), Kohno et al.
patent: 4929038 (1990-05-01), Reinartz et al.
patent: 5000420 (1991-03-01), Hendrixon
patent: 5167442 (1992-12-01), Alaze et al.
Graham Matthew C.
ITT Automotive Europe GmbH
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