Brake pressure difference warning system for vehicles
AssigneeAisin Seiki Kabushiki Kaisha
InventorMizuo Nyunoya
Life of this patent
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Abstract
A brake pressure-failure warning system for use with a split or dual type brake system having two brake lines includes a stepped piston operatively associated with an electrical warning switch and supplied with brake pressure from both of the brake lines, a proportioning valve disposed within the rear wheel brake line, and three fluid chambers, two of which are usually in fluid communication through the proportioning valve and a passage. When either one of the three fluid chambers is subjected to a hydraulic failure, the two chambers are in direct fluidic communication without fluid passing through the proportioning valve, the passage in effect being utilized as a by-pass passage under such hydraulic failure conditions.
Claims10
A brake pressure difference and failure warning system operatively associated with a dual type master brake cylinder having two independent brake lines, one brake line being fluidically connected to rear wheel brakes while the other brake line is fluidically connected to front wheel brakes, comprising:
- a housing provided with an axial bore therein;
- a stepped piston slidably disposed within said bore and provided with a small diameter portion and a large diameter portion;
- a proportioning valve assembly disposed within said one of said brake lines;
- a first fluid chamber defined within said housing at one end of said small diameter portion of said stepped piston and disposed within said one brake line;
- a second fluid chamber defined within said housing and around said smaller diameter portion of said stepped piston and fluidically connected to said rear wheel brakes;
- a passage provided within said housing and disposed within said one of said brake lines, said second fluid chamber being normally fluidically connected to said first fluid chamber through means of said proportioning valve assembly and said passage, said proportioning valve assembly thereby controlling the pressurization of said second chamber;
- a third fluid chamber defined within said housing at the large diameter end portion of said stepped piston and disposed within said other brake line;
- seal means provided upon said small diameter portion of said stepped piston, and interposed between said first and second fluid chambers for permitting fluid communication therebetween when said stepped piston is axially moved;
- switch means operatively connected to said stepped piston;
- said stepped piston having a predetermined configuration, and the stepped portions thereof having a predetermined area ratio with respect to each other, such that said stepped piston is axially movable, so as to actuate said switch means when each one of said first and third fluid chambers is subjected to a fluidic failure;
- and,
- when the proportioning valve is inoperatively seated on its valve seat with said first and said second fluid chambers not subjected to fluid failure such that the hydraulic pressure within said second fluid chamber is lower than the normal hydraulic pressure supplied to said second fluid chamber, fluid communication between said master cylinder and said rear wheel brakes is established through means of said first and second fluid chambers, and said passage;
- and
- means disposed within said axial bore for controlling the fluid communication between said first and second fluid chambers when said piston is axially moved in response to a fluidic failure.
Dependencies are inferred from the claim text.