Flow-control valve

Details Flow-control valve Flow-control valve

1998-07-14

1999-12-07

Hepperle, Stephen M.

Fluid handling

Line condition change responsive valves

Bi-directional flow valves

137501, G05D 701

Patent

active

059966157

DESCRIPTION:

BRIEF SUMMARY
The invention concerns a flow control valve in accordance with the preamble of claim 1.
The like flow control valves are preferably utilized if, for example, cylinders and motors in a hydraulic system are to be supplied with different and variable load pressures with a respective pre-selected, constant volume flow. I.e., the flow control valve determines the useful flow flowing to the user, for instance the hydrocylinder or the hydromotor. Fundamentally there are three possibilities of arranging flow control valves in hydrosystems, wherein the arrangement may be provided in the supply toward the user (primary control), in the drain of the user (secondary control), or in a bypass conduit of the hydropump (bypass control).
In the known flow control valves, serial arrangement of a fixedly adjustable narrowing, i.e. a restrictor orifice and a pressure regulator comprising a valve slide (control orifice) which is controllable in dependence on the variable pressure conditions, serves to maintain a constant pressure difference at the restrictor orifice, so that a constant flow through the flow control valve may be adjusted.
In FIG. 1, which shall even now be referred to, a two-way flow control valve is shown, as for example described in Data Sheet J2A 60 "2-Wege-Stromregelventil" [2-way Flow Control Valve], p. J.07, J.08 by the applicant.
Such a known flow control valve 1 includes a valve housing 2 having an axial bore as a valve bore 4, which in turn communicates with an inlet port P and on the other hand is closed by a throttle member 6 mounted in an axially slidable manner in the valve bore, with adjustment of the axial position being effected via an actuating means 8 which is accessible in the axial direction from the outside. The throttle member 6 includes a throttle pin 10 which projects into a throttle bush 12 so that, through co-operation of the throttle pin 10 and the throttle bush 12, the effective sectional area of the restrictor orifice is adjustable by axial displacement of the throttle member 6. The throttle bush 12 is supported on a front surface of the valve bore 4 and in the range of the throttle pin 10 provided with radial bores 14 whereby a connection of the inlet port P to an outlaw port A is achieved.
At the end portion of the throttle bush 12 removed from the throttle pin 10, a control spring 16 is supported which in turn biases a valve slide 18 guided in an axially slidable manner in the valve bore 4, and by the end portion thereof which is removed from the spring side the opening cross-section of the outlet port A may be controlled open or closed. The valve slide 18 has an inner bore, so that the port P is connected to the outlet pore A via the inner bore of the valve slide, the throttle bush (restrictor orifice) 12, and the radial bores 14. In the case of a flow in the direction of the longitudinal axis of the valve, the fluid flows through the inner bore of the valve slide 18 and through the adjustable ring gap of the restrictor orifice toward the controlled outlet. As soon as a pressure difference corresponding to the spring rate is reached between the inlet port P and the controlled outlet port A, the valve slide 18 is displaced to the left in the representation according to FIG. 1 such as to throttle the volume flow to the controlled outlet port A, and thus the pressure difference at the restrictor orifice is maintained constant. Owing to this constant pressure drop over the restrictor orifice, the controlled discharge volume flow is also maintained constant independently of the pressure fluctuations at the inlet port P. As was mentioned earlier on, the valve slide is only capable of varying the cross-section of the outlet port once the spring force of the control spring 16 is overcome. I.e., when the pressure difference over the restrictor orifice is greater than the spring force divided by the effective valve slide area.
Such flow control valves also permit flow through them in the reverse direction, i.e. from port A to port P, and in this case have a check valve effect, with the pr

REFERENCES:
patent: 3015341 (1962-01-01), Hedlund et al.
patent: 3145730 (1964-08-01), Presnell
patent: 3424196 (1969-01-01), Donner
patent: 4234013 (1980-11-01), Rikuta
patent: 4237922 (1980-12-01), Maier
patent: 4655245 (1987-04-01), Gellerso

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