Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Patent
1998-10-02
2000-08-01
Michalsky, Gerald A.
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
13711523, G05D 700
Patent
active
06095177&
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The invention is based on a precontrolled 3-way pressure control valve.
A 3-way pressure control valve of kind is known from the book "Hydraulik Trainer Band 1" [Hydraulics Trainer Volume 1], published in 1991 by Mannesmann Rexroth GmbH, pages 236 to 239. In this pressure control valve, the main piston has a piston bead by which the middle control chamber can be sealed off from the first and second control chambers and which is abutted on either side by a piston neck from which control grooves distributed around the circumference extend into the piston bead. The control grooves that begin at a piston neck are located at an axial distance from the control grooves departing from the other piston neck, said distance being approximately equal to the axial extent of the middle control chamber.
The pilot valve of the known precontrolled pressure-regulating valve is a direct-controlled pressure-regulating valve with a pressure connection, a tank connection, and a control connection. The control connection is connected with a pressure chamber in front of one end of the main piston by fluid. Control oil from the pressure connection of the main valve flows to the pressure connection of the pilot valve. Depending on the adjustment of a spring, a certain pressure is set in the control connection of the pilot valve and hence in front of one end of the main piston. The middle control chamber of the valve bore of the main valve is connected by a housing channel with a pressure chamber in front of the other end of the main piston. In each case, a pressure becomes established in the middle control chamber and hence in the control connection such that an equilibrium exists at the main piston between the various pressure and spring forces. A precontrolled 3-way pressure control valve in which the pilot valve is supplied with the control oil from the pressure connection of the main valve is referred to as being high-pressure-controlled. The special advantage of this type of precontrol consists in the main piston not tightening even with a large volume flow and a large pressure differential between the pressure connection and the control connection of the main valve, i.e. the connection between the pressure connection and the control connection is interrupted by the main piston and hence the applicability of the valve is limited. It is disadvantageous that the known precontrolled pressure control valve has a tendency toward instability under certain operating conditions, in other words pressure fluctuations occur at the control connection.
SUMMARY OF THE INVENTION
The object of the invention, with a valve of the above-mentioned type, is to provide precontrolled, 3-way pressure control valve that exhibits very stable behavior and does not tighten in response to large volume flows with a high pressure differential between the pressure connection and the control connection.
The 3-way pressure control valve according to the invention is low-pressure-controlled, since the control oil is supplied to the pilot valve, designed as a pressure-limiting valve, not from the pressure connection but from the control connection and/or from an area of the valve in which the regulating pressure prevails. The stability of the pressure-control valve is considerably improved by this type of control oil removal and by the type of pilot valve.
For a general understanding of a precontrolled 3-way pressure control valve it is sufficient to assume that in all the chambers of the valve openly connected with the control connection, the same static pressure prevails, namely the control pressure. On closer examination, however, it becomes evident that there are local deviations from the control pressure everywhere, caused by the geometry of the main piston and the hollow chambers in the valve housing, and that therefore the geometry and the point at which the control oil flowing to the pilot valve is removed influence the function of the pressure control valve. In a precontrolled 3-way pressure control valve accord
REFERENCES:
patent: 4321941 (1982-03-01), Hunschede et al.
patent: 4463660 (1984-08-01), Mucheyer et al.
patent: 4531707 (1985-07-01), Dotti et al.
patent: 4785849 (1988-11-01), Masuda
Grundlagen und Komponenten der Fluidtechnik Hydraulik, Hydraulics Trainer vol. 1, published by Mannesmann Rexroth GmbH, pp. 236 to 239, (RD 00290/10.91).
Machat Gotz-Dieter
Meyer Karl-Josef
Stroka Wilfried
Zugner Jurgen
Farber Martin A.
Mannesmann Rexroth AG
Michalsky Gerald A.
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