Hydraulic ABS modulator
AssigneeGeneral Motors Corporation
InventorDavid F. Reuter
Life of this patent
Estimating the term…
Abstract
An ABS hydraulic modulator suitable for vehicular applications is provided. The design utilizes an electric motor which powers a hydraulic pump unit used to recirculate brake fluid during ABS operation. The hydraulic circuit components also include a normally closed ABS release solenoid valve, an integral spring-loaded piston accumulator, an isolation valve and check arrangement, a number of strategically placed flow control orifices and an optional hydraulic damper assembly.
Claims8
A brake system modulator having a master cylinder port, a wheel brake port and a bore comprising:
- an isolation valve assembly including a piston slidably carried in the bore and having a first side and a second side, and including an obturator engageable with the first side of the piston and a spring engaging a spring side of the obturator biasing the obturator toward the piston with a first chamber defined in the bore on the first side of the piston, a second chamber defined in the bore on the second side of the piston and a third chamber defined in the bore on the spring side of obturator;
- an ABS release solenoid valve movable between a closed and an open position and communicating with the bore at the second chamber on the second side of the piston through a first conduit extending from the isolation valve assembly to the ABS release solenoid valve;
- a pump having an outlet check valve;
- a continuously open flow path through the modulator between the master cylinder and the wheel brake port including an ABS apply orifice assembly with a thin element having an opening forming an ABS apply orifice positioned in the continuously open flow path;
- and
- a second conduit extending from the ABS apply orifice to the first chamber of the isolation valve assembly wherein when the ABS release solenoid valve is moved to the open position to effect a pressure reduction at the wheel brake port the continuously open flow path remains open in both directions between the master cylinder port and the wheel brake port.
A modulator for operation in a brake system including a master cylinder and a wheel brake operating on fluid, the modulator comprising:
- an isolation valve assembly having a piston, a seat and an obturator wherein the piston is normally engageable with the obturator to move the obturator away from the seat, opening the isolation valve assembly;
- an orifice assembly having a square cornered opening forming a flow restrictive orifice wherein fluid flow from the master cylinder to the wheel brake through the modulator is normally through both a first path through the flow restrictive orifice and a second path that is independent of the first path through the seat of the isolation valve assembly;
- a solenoid operated normally closed valve;
- a pump integrated into the modulator;
- and
- an accumulator communicating with the pump and selectively communicating with the wheel brake through the solenoid operated normally closed valve wherein the modulator is operable to limit wheel slip by starting the pump and opening the normally closed valve permitting a release of pressure from the wheel brake to the accumulator and, when necessary, a pressure increase at the wheel brake is effected by closing the normally closed valve so that the pump supplies a fluid flow to the wheel brake through the square cornered opening that is controlled by the orifice assembly based on a pressure differential between the master cylinder and the wheel brake.
Dependencies are inferred from the claim text.