Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1993-10-12
1995-10-03
Look, Edward K.
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
91380, 92 136, 1801325, F15B 910, F01B 3114
Patent
active
054542901
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hydraulic control device comprising, on the one hand, a valve which can be moved along an axial direction inside a sealed casing filled with a fluid whose flow is at least controlled by this valve and, on the other hand, opening means which enable this movable valve to be opened in a selective fashion when it is moved, under the effect of a first axial force of higher intensity than a first threshold, into an open position, and this open position to be chosen from a range of possible positions extending along the axial direction.
Such devices are especially used in order to determine the operating range of hydraulically assisted steering systems for motor vehicles.
In these systems, assistance in maneuvering the steering wheel is obtained by a modulation of the hydraulic pressure in complementary chambers delimited by a piston inside a cylinder, the operating range of the system being determined by the stroke of this piston.
This stroke is itself defined by means of stop valves, open at the end of the stroke of the piston by virtue of the movement of the latter, and establishing, between the chambers, a passage of hydraulic fluid preventing any further modification in the pressure modulation in the same direction.
Such a device is, for example, described in the U.S. Pat. No. 3 315 570, several variants of which are known in the prior art.
Regardless of their means of production, the known devices have the fault of requiring, for setting the opening position of the movable valve, a dismantling of the casing in which it is to be found and/or recourse to relatively significant additional setting means.
In this context, the object of the invention is to provide a hydraulic control device with a movable valve of simple structure which is easy to manufacture and nevertheless allows setting of the opening position of the valve from the outside of the casing in which it is housed.
To this end, the device of the invention is provided with settable opening means comprising: having one end in contact with which this valve can open when it is forced there by the first axial force; first and of lower intensity than the first threshold, these elastic means being sufficiently deformable to apply the second axial force to the stop regardless of the point of the said range at which the end of this stop is located; and preventing the stop from sliding in its housing under the effect of axial forces of lower intensity than a second threshold, itself higher than the first threshold.
The blocking means may, for example, comprise a screw capable of moving in a bore which is at least partially tapped emerging into the said housing.
Furthermore, these blocking means preferably comprise a bearing bush bearing against the stop and a spring compressed by the screw and itself pressing on the bearing bush.
In a simple embodiment, the elastic means essentially comprise a spring trapped between the bottom of the housing and the axial stop.
Other features and advantages of the invention will emerge clearly from the description which is given below, by way of example and in no way limiting, with reference to the appended drawings in which:
FIG. 1 is a sectional view of a device in accordance with the invention, used in a system viewed in partial section.
FIG. 2 is a view similar to that of FIG. 1, relating to a second embodiment of the invention.
The figures represent a portion of a power-assisted steering system especially comprising a sealed casing 1 and a movable piston 2 delimiting at least one pressure chamber 3 filled with a hydraulic fluid.
The chamber 3 is closed in a sealed fashion by the piston 2, but a flow of fluid towards the outside of this chamber is possible, in a controlled fashion, by virtue of a movable valve 4 carried by the piston 2 and moving with it along the direction of the axis 5.
The movable valve 4 comprises a flap 4a forced against a seat 4b by a spring 4c exerting a force corresponding to a first threshold.
It is therefore possible, by exerting on the flap a an axial force d
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patent: 4699231 (1987-10-01), Lang et al.
patent: 5322142 (1994-06-01), Elser
Bacardit Juan Simon
Cortes Guasch Esteve
Bendix Espana S.A.
Look Edward K.
McCormick Jr. Leo H.
Nguyen Hoang
Palguta Larry J.
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