Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1995-08-23
1998-06-16
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
13762565, 25112921, 3031152, B60T 836
Patent
active
057659303
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to pressure-regulating solenoid valves for hydraulic circuits, more particularly but not exclusively to solenoid valves intended for the braking circuits of motor vehicles, provided with an antilock braking system.
Current antilock braking systems employ, between a source of pressurized fluid and a pressure receiver such as a brake motor, a solenoid valve commanded by a computer on the basis of signals representing the speed of rotation of the wheels in order, in general, to relieve the pressure of the fluid in the brake motor when the computer detects imminent locking of the wheel associated with this brake motor, then to connect a second source of pressurized fluid in order to increase the hydraulic pressure in the brake motor again until imminent locking is detected again, the pressure relief and raising cycle then recommencing.
The solenoid valves used operate most of the time in all-or-nothing mode, one solenoid valve being used to relieve the pressure in the brake motor, and another to make the pressure in this brake motor rise again, this being for each wheel of the vehicle.
These successive phases of relieving the pressure and making it rise again each last for a very short period of time and follow on rapidly from one another, which results in the solenoid valves changing state rapidly many times. This gives rise to significant noise due to the beating of the movable part of these solenoid valves, accompanied by abrupt changes in pressure in the brake motors, giving rise to transient ill-controlled conditions.
In order to avoid these drawbacks, it has since been proposed, for example in the documents FR-A-2,679,299 or FR-A-2,683,338, to use three-way solenoid valves of the proportional type. They allow, on the one hand, use of just one solenoid valve per wheel of the vehicle to be commanded, and, on the other hand, they operate much more quietly.
Such proportional solenoid valves nevertheless still have the drawback of exhibiting a significant overall size. Indeed, these solenoid valves most of the time are made up of a purely electrical part including the electrical coil, the pole pieces and a movable magnetic core, and a purely hydraulic part including a distributor slide valve sliding in a bore or a sleeve formed in a body including various hydraulic ducts, the connection between these two parts being effected by a push rod integral with the movable magnetic core on which the distributor slide valve comes to bear.
Such an in-line arrangement of the electrical and hydraulic parts gives known solenoid valves longitudinal dimensions which may make it difficult, or even impossible, to install them in the event of the space given over to them being too limited.
The object of the present invention is therefore to propose a pressure-regulating solenoid valve which exhibits a reduced overall size, and this being without increasing either the difficulties of manufacture or consequently the cost, and the operation of which is reliable under all circumstances.
To this end, the invention proposes a pressure-regulating solenoid valve for a hydraulic circuit comprising at least one generator of pressurized fluid, a pressure receiver and a reservoir of fluid under low pressure, the solenoid valve including an electrical coil interacting with two pole pieces, a magnetic body which can move under the effect of an actuating force generated by a magnetic field created by the electrical coil, and a distributor element interacting with a sleeve structure in order to command the communication between a duct connected to the pressure receiver and one or other of ducts connected to the generator of pressurized fluid, and to the reservoir of fluid under low pressure, the solenoid valve including at least one reaction chamber permanently communicating with the pressure receiver and determining a reaction force which is added to the actuating force generated by the coil, counter to the force generated by a preloaded elastic means on the movable magnetic body.
According to the present inventi
REFERENCES:
patent: 4619289 (1986-10-01), Tsuru et al.
patent: 4714300 (1987-12-01), Heess et al.
patent: 5005919 (1991-04-01), Shuey et al.
patent: 5445189 (1995-08-01), Yamamuro
Bourlon Philippe
Cheron Jean Marc
Kervagoret Gilbert
Bosch System De Freinage
Comstock Warren
Graham Matthew C.
McCormick Jr. Leo H.
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