Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Patent
1998-11-23
1999-12-07
Hepperle, Stephen M.
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
F16K 1704
Patent
active
059966165
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a hydraulic pressure-reducing valve with an upstream control valve.
Pressure-reducing valves and control valves are already known as individual components in a wide variety of forms.
For hydraulic activation of certain devices, e.g. a holding brake, it is necessary to connect a control valve upstream of the pressure-reducing valve in order to achieve a defined activation characteristic, for example as shown in FIG. 4. In addition to a low-pressure range, in which the valve is not supposed to respond, a proportional control range and a pressure-limiting range, in which the control pressure is limited to a maximum pressure, are to be created. Hitherto it was customary to produce this control characteristic by having several single valves, in particular a control valve and a pressure-reducing valve, connected together as single components. However, this solution consisting of several single valves is costly and requires a relatively large installation space owing to the minimum of two single valves to be provided. A relatively complex construction results, especially if a discharge throttle is to be provided in addition.
The object of the invention is therefore to combine the functions of a control valve and a pressure-reducing valve in a single combined hydraulic valve.
This object is achieved by the features of claim 1.
The invention is based on the formulated solution of displacing an actuating piston proportionally to a supply pressure and of assigning to the actuating piston different control functions in the range between the starting position and a minimum displacement, the range between the minimum displacement and maximum displacement and on reaching the maximum displacement respectively.
Claims 2 to 14 contain advantageous developments of the invention.
According to claim 2, a third pressure medium connection can be provided on the hydraulic valve according to the invention, which connection is connected to the second pressure medium connection via a throttle. A discharge throttle can thus be integrated additionally into the hydraulic valve according to the invention, so that the number of functions of the hydraulic valve according to the invention and the degree of integration can be increased further. According to claim 3, the throttle can be formed simply on the actuating piston as a flattening, notch or hole, which is particularly easy to realize in manufacturing technology.
The restoring force proportional to the supply pressure can be exerted for example according to claim 5 by a restoring spring formed on the end opposing the pressure surface, which spring can likewise be integrated easily into the valve casing. The restoring force exerted by the restoring spring can be adjustable advantageously according to claim 6 by changing the position of a spring plate, so that the characteristic of the hydraulic valve according to the invention is adjustable from outside the valve body.
A first annular groove can be formed according to claim 7 on the control piston, one lateral edge of which groove according to claim 8 advantageously forms the second control edge. The pressure-reducing or pressure-limiting function is assigned here to the control edge formed on the first annular groove. A second annular groove can be formed accordingly on the actuating piston according to claim 10, one lateral edge of which groove according to claim 11 advantageously forms the first control edge. Assigned to the second annular groove here is the control function on reaching the minimum displacement of the actuating piston corresponding to the first threshold value of the supply pressure and the pressure-regulating function proportional to the supply pressure in the range between the minimum and maximum displacement of the actuating piston. The first annular groove, second annular groove and a pressure chamber of the valve body adjacent to the pressure surface of the actuating piston can be connected to one another via one or more holes provided in the actuating piston according to claim 12.
Fur
REFERENCES:
patent: 1959909 (1934-05-01), Farmer
patent: 2630825 (1953-03-01), Stephens
patent: 4237933 (1980-12-01), Bauer
Brueninghaus Hydromatik GmbH
Hepperle Stephen M.
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