Valves and valve actuation – Electrically actuated valve – With means to bias valve open
Patent
1998-08-07
2000-11-28
Lee, Kevin
Valves and valve actuation
Electrically actuated valve
With means to bias valve open
3031192, F16K 3106
Patent
active
061524204
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on an electromagnetically actuated valve for hydraulic motor vehicle brake systems.
In slip-controlled hydraulic brake systems, valves are used which in their electromagnet-actuated closing position are subjected to very strong hydraulic opening forces. The electromagnetic circuit of these valves must therefore, in the valve closing position, bring to bear a holding-closed force on the magnet armature that is greater than the maximum hydraulic opening force plus the force of a restoring spring. A magnetic circuit designed in this way requires corresponding space for installation and with other disadvantages prevents the disposition of such valves in a space-saving, tight package.
German Patent Application DE 31 26 246 A1 discloses a valve of this generic type in which to reduce the holding-closed force by means of pressure equilibrium operative at the tappet, a relatively short pin in the end portion toward the valve dome of the tappet that is passed through the magnet armature and form-lockingly united with it is disposed, such that it is movable for steering purposes, in a longitudinal bore of the tappet. A force originating in the inflow-side pressure on the pin is therefore deviated via the valve dome to the valve housing. This provision allows making the magnet circuit smaller in size. Functionally, the known valve is a 2/2-way valve, which has only two switching positions, in which the full flow cross section of a seat valve is either uncovered or fully blocked. This lessens the mobility of such valves. Moreover, their considerable switching noises are often disadvantageous.
ADVANTAGES OF THE INVENTION
The valve according to the invention has the advantage over the prior art that in a way similar to a proportional valve, it can be transferred, by controlling the magnetic force and with short strokes, to an arbitrary number of intermediate positions but without having to have the complicated design of a proportional valve. This mode of operation can be ascribed to the fact that the restoring spring essentially determines the course of the force engaging the tappet over the valve stroke, while the hydraulic force acting on the closing member has only subordinate influence, because of the diameter ratios of the inflow bore and the sealing diameter of the valve seat and because of the force deviation to the valve dome. A largely continuous flow control is therefore attainable with the valve of the invention. In many applications it can be used instead of proportional valves. In slip-controlled brake systems, the use of the valve of the invention makes it possible to achieve a higher closed-loop control quality and lower noise emissions than in the known valve.
By means of the provisions recited in the dependent claims, advantageous refinements of and improvements to the valve defined by claim 1 are possible.
With the embodiments defined herein a more-defined separation of the stream of pressure medium from the closing member or the valve seat is attained after the valve opens. Unstable flow forces are thus largely avoided.
The refinement of the invention defined has the advantage that a stream of pressure medium once separated from the closing member and the valve seat, in its further course now no longer strikes the tappet. This precludes disruptive influences of flow forces.
With the embodiment of the invention defined hereinafter, it is possible in a simple way to adjust the spring force of the restoring spring, for instance in the closing position of the seat valve, by adjusting the position of the sleeve relative to the tappet.
BRIEF DESCRIPTION OF THE DRAWINGS
One exemplary drawing of the invention is shown in simplified form and described in further detail in the ensuing description.
FIG. 1 shows a longitudinal section through an electromagnetically actuated valve with a seat valve;
FIG. 2 shows a detail II of FIG. 1 in the form of the seat valve, in the closing position, on a larger scale than in FIG. 1; and
FIG. 3 shows a graph of the forces operative in t
REFERENCES:
patent: 5673980 (1997-10-01), Schwarz et al.
patent: 5791628 (1998-08-01), Wolff et al.
Greigg Edwin E.
Greigg Ronald E.
Lee Kevin
Robert & Bosch GmbH
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