Motors: expansible chamber type – With motive fluid valve – Electrically operated
Patent
1993-05-04
1995-05-02
Michalsky, Gerald A.
Motors: expansible chamber type
With motive fluid valve
Electrically operated
13759617, 13762565, 3031192, F15B 13044
Patent
active
054109434
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a pressure regulation device for a hydraulic system.
It is particularly suited to motor vehicle braking systems with anti-locking of the wheels during braking, and/or anti-wheelspin during acceleration. Current anti-locking systems use, between a source of fluid under pressure and a hydraulic receiver such as a brake actuator, an electrovalve controlled by a computer as a function of signals representative of the rotation of the wheels of the vehicle, in order, in a general manner, to release the pressure of the fluid in the brake actuator when the computer detects the imminence of the locking of a wheel, and then to connect a second source of fluid under pressure so as to raise the pressure once more, until the imminence of locking is detected once again, the cycle then renewing itself. Electrovalves of the same type are used in anti-wheelspin systems in order to generate a pressure in a brake actuator of a driving wheel when the computer detects a tendency of this driving wheel to spin, and then to release this pressure when the tendency to spin has disappeared.
The electrovalves used are electrovalves operating in all-or-nothing manner, one electrovalve being used in order to release the pressure, another in order to raise the pressure, and this for each wheel of the vehicle. However the periods of anti-locking or anti-wheelspin in which cycles as described above succeed one another, last for a very short time during which the electrovalve changes state a very large number of times. This causes an unpleasant noise of hammering of the movable part of the electrovalve, multiplied by the number of electrovalves.
Moreover, as the electrovalves operate in all-or-nothing manner, pressure surges appear in the brakes producing poorly controlled transient conditions.
The present invention has the object of obviating these disadvantages by using an electrovalve termed proportional producing in the user system the phases of release of pressure and of raising of pressure as a function of the current circulating in the coil of the electrovalve in a given range of displacement of the magnetic core of the electrovalve.
Anti-locking and/or anti-wheelspin braking systems using proportional electrovalves are known, moreover, for example from WO-A-91/15388 or EP-A-0,254,483, which systems lead to relatively complex and therefore costly production.
Such an anti-locking or anti-wheelspin system then has the advantage of being controllable simply by causing to vary the current circulating in a single coil per monitored wheel of the vehicle; this therefore results in a large reduction in the pressure surges in the brakes. In addition, such an electrovalve may easily be of simplified design, resulting in a simplified assembly. This, combined with a large reduction in the number of the components of an anti-locking or anti-wheelspin system, reduces considerably the cost of such a system.
The subject of the present invention is therefore a pressure regulation device for a hydraulic system comprising at least one generator of fluid under pressure, a brake actuator and a reservoir of fluid under low pressure, and including a proportional electrovalve controlled by a computer, the electrovalve being connected via a duct to the generator of fluid under pressure and via a duct to the brake actuator, and comprising in a casing an electrical coil and a sliding magnetic core controlling a slide valve determining two chambers arranged on either side of the slide valve and being formed with a valve with ball co-operating with a seating formed on the casing, the slide valve being formed with a groove delimited by two bearing surfaces, one of the bearing surfaces co-operating with the duct for connection with the hydraulic actuator and having a length greater than the diameter of that duct by a length representing a functional overlap.
The invention will now be described by way of example with reference to the accompanying drawings [sic] in which:
The single FIGURE shows diagrammatically in section an embodiment of
REFERENCES:
patent: 3880476 (1976-04-01), Belart et al.
patent: 4744389 (1988-05-01), Ichihashi
patent: 5234030 (1993-08-01), Kervagoret et al.
patent: 5248191 (1993-09-01), Kondo et al.
Fabian et al, Machine Design, pp. 59-62, Jan. 24, 1991.
AlliedSignal Europe Services Techniques
Michalsky Gerald A.
Palguta Larry J.
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