Fluid handling – Systems – Supply and exhaust
Reexamination Certificate
1999-09-09
2001-12-11
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Supply and exhaust
C251S129140
Reexamination Certificate
active
06328065
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is based on an electromagnetic pressure regulating valve. A pressure regulating valve of this type is already known, for example, from DE 43 42 591 A1. This pressure regulating valve has, in its housing, a valve slide which is guided so as to be movable and whose position can be adjusted electromagnetically. The instantaneous regulating position of the valve slide can constantly be changed by a corresponding supply of current to its magnetic coil. In order for the pressure regulating valve to function properly in accordance with its application, great precision is required in the manufacture of the valve slide and slide guidance. The latter is a crucial factor in the tightness of the pressure regulating valve and its manufacturing cost. In addition, the valve slide requires a relatively high actuating force due to its relatively large effective pressure surfaces.
Further, DE 43 37 763 A1 discloses a valve which is referred to as a pressure regulating valve but which, in contrast to the subject matter of the invention, acts as a switching valve, its valve part being outfitted with two seat valves. One of the valve elements of the two seat valves is shaped conically and therefore necessitates a precise concentric arrangement with respect to its valve seat, which is expensive to carry out. In contrast to the subject matter of the invention, this known valve can be switched to three defined switching positions and is therefore incapable of generating at the consumer a continuous pressure regulating characteristic dependent on the current flowing to the magnet coil.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electromagnetic pressure control valve which avoids the disadvantages of the prior art.
In keeping with these objects, the valve part of the valve has a first seat valve with a closing element and an actuating element which is switched between the armature and the closing element, and the actuating element penetrates a control borehole of the valve part and has a control edge which forms a second seat valve in cooperation with the control borehole.
In contrast to the prior art, the electromagnetic pressure regulating valve according to the invention has the advantage that it ensures a relatively high degree of tightness, especially in its end positions, with reduced requirements for the precision of its individual structural component parts. Accordingly, functional characteristics, including unwanted leakage, can be improved while reducing production costs. This is achieved by means of constructing the valve elements in a seat type construction, which has the further advantage that the pressure regulating valve has a relatively low sensitivity to coaxial deviations and to blocking due to particles of dirt from the pressure medium. The operating range of the pressure regulating valve is expanded with respect to low pressures, has a continuous pressure regulating characteristic and requires relatively small magnetic actuating forces.
The surface ratio of less than 0.3 between the hydraulically active surfaces of the two seat valves makes it possible for the closing force of the second seat valve facing the magnet part to be greater than the opening force of the first seat valve remote of the magnet part. Therefore, the pressure regulated at the consumer, whose pressure force on the valve slide is in equilibrium with the force of the magnetic circuit, depends decisively on the precision of the first valve seat. The second seat valve can be constructed with reduced precision for cost reasons. Moreover, the bore hole of the second seat valve already assumes its full throttling function at small portions of the total lift of the valve element. This depends substantially on the manufacturing tolerances of the bore hole and not on the opening lift. Bore holes with exacting tolerances can be produced in an economical manner. Accordingly, the regulating pressure of the pressure regulating valve can be adjusted at low cost in a particularly accurate manner up to the very low pressure ranges. Flat seat valves are characterized in particular by good sealing properties while requirements for the concentric arrangement of the valve element with respect to the valve seat are relatively relaxed at the same time.
REFERENCES:
patent: 2868494 (1959-01-01), Kearns et al.
patent: 4312380 (1982-01-01), Leiber et al.
patent: 4338966 (1982-07-01), Smith
patent: 4998559 (1991-03-01), McAuliffe
patent: 5076323 (1991-12-01), Schudt
patent: 5104091 (1992-04-01), Rathay et al.
patent: 5135027 (1992-08-01), Miki et al.
patent: 5606992 (1997-03-01), Erickson et al.
patent: 5651391 (1997-07-01), Connolly et al.
patent: 43 42 591 A1 (1995-06-01), None
Ott Christof
Schmid Werner
Schuurman Raymond
Michalsky Gerald A.
Robert & Bosch GmbH
Striker Michael J.
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