Anti-lock brake system

Claim 2

In a motor vehicle having a fluid pressure operated brake actuating device, a pump, and a reservoir, the combination comprising; conduit means communicating operating fluid from the pump means to the brake actuating device; open center valve means including a movable valve seat member and a movable valve member and communicating the operating fluid from the pump means to the fluid reservoir when in the open center position whereby the operating fluid pressure is substantially zero; means including the pressure force of the operating fluid for holding the valve seat member normally stationary; operator actuatable means adapted to progressively move the valve member relative the valve seat member to restrict fluid communication with the reservoir thereby providing operating fluid pressure to the brake actuating device; an accumulator; a check valve for communicating operating fluid to the accumulator whenever the operating fluid pressure exceeds the accumulator pressure; and valve means including the normally stationary movable valve seat member for normally blocking communication of accumulator pressure to the brake actuating device, the valve seat member being engaged and moved by the valve member when force applied thereagainst by the operator actuatable means exceeds the force of the means for holding the valve seat member stationary whereby the accumulator pressure is communicated to the brake actuating device.

Claim 3

In a motor vehicle having a fluid pressure operated brake actuating device, a pump providing a source of fluid flow and pressure, and a reservoir, the combination comprising: a housing forming a first chamber in fluid communication with the pump means and a second chamber in fluid communication with the reservoir; a lockout piston having axially spaced lands slidably engaging the housing and forming therewith a third chamber; an accumulator in fluid communication with the third chamber, the accumulator pressure holding the lockout piston in a normal position in the housing; check valve means communicating operating fluid from the first chamber to the third chamber whenever the first chamber pressure exceeds the third chamber pressure; a valve seat member having a fluid passage therethrough connecting the first and second chambers, the valve seat member being slidable in the lockout piston and forming therewith a first valve selectively permitting communication between the first and third chambers; means including the operating fluid pressure in the first chamber for holding the first valve normally closed; a valve member in the second chamber being normally spaced from the fluid passage through the valve seat member to permit unrestricted fluid communication from the pump means to the reservoir; operator actuatable means slidable in the housing and connected for moving the valve member into flow restricting proximity with the valve seat member to increase the first chamber pressure, for further moving the valve member into engagement with and moving the valve seat member to open the first valve and thereby communicate third chamber pressure to the first chamber.

Claim 4

In a motor vehicle having a fluid pressure operated brake actuating device, a pump providing a source of fluid flow and pressure, and a reservoir, the combination comprising: a housing forming a first chamber in fluid communication with the pump means and a second chamber in fluid communication with the reservoir; a lockout piston having axially spaced lands slidably engaging the housing and forming therewith a third chamber; an accumulator in fluid communication with the third chamber, the accumulator pressure holding the lockout piston in a normal position in the housing; check valve means communicating operating fluid from the first chamber to the third chamber whenever the first chamber pressure exceeds the third chamber pressure; a valve seat member having a fluid passage therethrough connecting the first and second chambers, the valve seat member being slidable in the lockout piston and forming therewith a first valve selectively permitting communication between the first and third chambers; means including the operating fluid pressure in the first chamber for holding the first valve normally closed; a valve member in the second chamber being normally spaced from the fluid passage through the valve seat member to permit unrestricted fluid communication from the pump means to the reservoir; operator actuatable means slidable in the housing and connected for moving the valve member into flow restricting proximity with the valve seat member to increase the first chamber pressure, for further moving the valve member into engagement with and moving the valve seat member to open the first valve and thereby communicate third chamber pressure to the first chamber.

Claim 5

In a motor vehicle having a plurality of fluid pressure operated wheel brakes, a plurality of master cylinders, each master cylinder being fluidly connected to at least one wheel brake, a fluid pressure operated booster associated with each master cylinder for actuation thereof, a pump means providing a source of fluid flow and pressure, and a reservoir, the combination of: conduit means communicating the operating fluid from the pump means to each of the boosters; a housing forming a first chamber in fluid communication with the pump means and a second chamber in fluid communication with the reservoir; a lockout piston having axially spaced lands slidably engaging the housing and forming therewith a third chamber; an accumulator in fluid communication with the third chamber, the accumulator pressure holding the lockout piston in a normal position in the housing; check valve means communicating operating fluid from the first chamber to the third chamber whenever the first chamber pressure exceeds the third chamber pressure; a valve seat member having a fluid passage therethrough connecting the first and second fluid chambers, being slidable in the lockout piston, and forming therewith a first valve selectively permitting communication between the first and third chambers; means holding the first valve normally closed; a valve member in the third chamber being normally spaced from the fluid passage through the first valve seat member to permit unrestricted fluid communication from the pump means to the reservoir; operator actuable means slidable in the housing and connected for moving the valve member into flow restricting proximity with the valve seat member to increase the first chamber pressure, for further moving the valve member into sealing engagement with the valve seat member to open the first valve and being further movable to engage and move the lockout piston subsequent to a substantial dissipation of third chamber pressure; a force transmitting linkage connecting the operator actuable means with the plurality of master cylinders for actuation thereof upon overtravel of the operator actuable means consequent with movement of the lockout piston; and anti-lock valve means in said conduit means fluidly intermediate the pump means and at least one of the boosters and adapted to selectively reduce and reapply the operating fluid pressure to the booster.

Claim 6

In a motor vehicle having a plurality of fluid pressure operated wheel brakes, a plurality of master cylinders, each master cylinder being fluidly connected to at least one wheel brake, a fluid pressure operated booster associated with each master cylinder for actuation thereof, a pump means providing a source of fluid flow and pressure, and a reservoir, the combination of: conduit means communicating the operating fluid from the pump means to each of the boosters; a housing forming a first chamber in fluid communication with the pump means and a second chamber in fluid communication with the reservoir; a lockout piston having axially spaced lands slidably engaging the housing and forming therewith a third chamber; an accumulator in fluid communication with the third chamber, the accumulator pressure holding the lockout piston in a normal position in the housing; check valve means communicating operating fluid from the first chamber to the third chamber whenever the first chamber pressure exceeds the third chamber pressure; a valve seat member having a fluid passage therethrough connecting the first and second fluid chambers, being slidable in the lockout piston, and forming therewith a first valve selectively permitting communication between the first and third chambers; means holding the first valve normally closed; a valve member in the third chamber being normally spaced from the fluid passage through the first valve seat member to permit unrestricted fluid communication from the pump means to the reservoir; operator actuable means slidable in the housing and connected for moving the valve member into flow restricting proximity with the valve seat member to increase the first chamber pressure, for further moving the valve member into sealing engagement with the valve seat member to open the first valve and being further movable to engage and move the lockout piston subsequent to a substantial dissipation of third chamber pressure; a force transmitting linkage connecting the operator actuable means with the plurality of master cylinders for actuation thereof upon overtravel of the operator actuable means consequent with movement of the lockout piston; and anti-lock valve means in said conduit means fluidly intermediate the pump means and at least one of the boosters and adapted to selectively reduce and reapply the operating fluid pressure to the booster.

Claim 7

In a motor vehicle having wheels, fluid pressure operated wheel brakes adapted to impart braking effort to the wheels, means providing braking pressure for operation of the wheel brakes, brake pressure controlling means responsive to pressure variations and effective to modulate braking pressure to the wheel brakes for preventing wheel lockup, pump means including a reservoir and providing fluid pressure for operation of the brake pressure controlling means, and wheel condition sensing and control logic means, a fail safe valve circuit operated by the wheel condition sensing and control logic means and adapted to provide the pressure variations for operation of the brake pressure controlling means and comprising: first conduit means connecting the pump means and the brake pressure controlling means; normally open valve means in the first conduit means being shifted by the wheel condition sensing and control logic means upon impending wheel lock to block fluid communication therethrough; a first flow rate control valve in parallel flow relationship with the normally open valve means and providing fluid communication at a limited rate from the pump means to the brake pressure controlling means; second conduit means connecting the brake pressure controlling means and the reservoir; a second flow rate control valve in the second conduit means limiting the rate of fluid communication therethrough to a lesser extent than the first flow rate control valve and to a greater extent than the combined fluid communication through the normally open valve means and the first flow rate control valve; and normally closed valve means in the second conduit means being cyclically shifted between the normal closed position and an open position during the sensed wheel lock condition whereby the pressure at the brake pressure controlling means is cyclically reduced through the second flow rate control valve and increased through the first flow rate control valve, the normally closed valve means remaining in the closed position when the wheel lock condition has been arrested and the normally open valve means being returned to the open position to reestablish unrestricted fluid communication between the pump means and the brake pressure controlling means.

Claim 8

In a motor vehicle having wheels, fluid pressure operated wheel brakes adapted to impart braking effort to the wheels, means providing braking pressure for operation of the wheel brakes, brake pressure controlling means responsive to pressure variations and effective to modulate braking pressure to the wheel brakes for preventing wheel lockup, pump means including a reservoir and providing fluid pressure for operation of the brake pressure controlling means, and wheel condition sensing and control logic means, a fail safe valve circuit operated by the wheel condition sensing and control logic means and adapted to provide the pressure variations for operation of the brake pressure controlling means and comprising: first conduit means connecting the pump means and the brake pressure controlling means; normally open valve means in the first conduit means being shifted by the wheel condition sensing and control logic means upon impending wheel lock to block fluid communication therethrough; a first flow rate control valve in parallel flow relationship with the normally open valve means and providing fluid communication at a limited rate from the pump means to the brake pressure controlling means; second conduit means connecting the brake pressure controlling means and the reservoir; a second flow rate control valve in the second conduit means limiting the rate of fluid communication therethrough to a lesser extent than the first flow rate control valve and to a greater extent than the combined fluid communication through the normally open valve means and the first flow rate control valve; and normally closed valve means in the second conduit means being cyclically shifted between the normal closed position and an open position during the sensed wheel lock condition whereby the pressure at the brake pressure controlling means is cyclically reduced through the second flow rate control valve and increased through the first flow rate control valve, the normally closed valve means remaining in the closed position when the wheel lock condition has been arrested and the normally open valve means being returned to the open position to reestablish unrestricted fluid communication between the pump means and the brake pressure controlling means.

Claim 9

In a motor vehicle having a plurality of fluid pressure operated wheel brakes, each master cylinder being fluidly connected to at least one wheel brake, a fluid pressure operated booster associated with each master cylinder for actuation thereof, and means providing fluid pressure for operation of the boosters, the combination of: first conduit means connecting the means providing fluid pressure and the plurality of boosters; a single normally open valve means in the first conduit means being shifted upon impending wheel lock to block fluid communication therethrough; a plurality of cHeck valve means in the first conduit means each being fluidly intermediate the normally open valve means and one of the boosters and permitting fluid communication through the first conduit only in the direction from the means providing fluid pressure to the booster; a first plurality of flow rate control valves, each being connected in parallel flow relationship with the normally open valve means and one of the check valve means and providing fluid communication at a limited rate from the means providing fluid pressure to the associated booster; second conduit means connecting each of the boosters with the reservoir; a second plurality of flow rate control valves in the second conduit means, each being fluidly intermediate one of the boosters and the reservoir and each limiting the rate of fluid communication therebetween to a lesser extent than the associated flow rate control valve in the first conduit means and to a greater extent than the combined fluid communication through the normally open valve means and the associated flow rate control valve in the first conduit means; and a plurality of normally closed valve means in the second conduit means, each being fluidly intermediate one of the boosters and the reservoir and being individually cyclically shifted between the normal closed position and an open position during the sensed wheel lock condition whereby the pressure at the associated booster is cyclically reduced at a controlled rate through the flow rate control valve in the second conduit means and increased through the flow rate control valve in the first conduit means, the normally closed valve means remaining in the closed position when the wheel lock condition has been arrested and the normally open valve means being returned to the open position to reestablish unrestricted fluid communication between the means providing operating fluid and the booster.

Claim 10

In a motor vehicle having a plurality of fluid pressure operated wheel brakes, each master cylinder being fluidly connected to at least one wheel brake, a fluid pressure operated booster associated with each master cylinder for actuation thereof, and means providing fluid pressure for operation of the boosters, the combination of: first conduit means connecting the means providing fluid pressure and the plurality of boosters; a single normally open valve means in the first conduit means being shifted upon impending wheel lock to block fluid communication therethrough; a plurality of cHeck valve means in the first conduit means each being fluidly intermediate the normally open valve means and one of the boosters and permitting fluid communication through the first conduit only in the direction from the means providing fluid pressure to the booster; a first plurality of flow rate control valves, each being connected in parallel flow relationship with the normally open valve means and one of the check valve means and providing fluid communication at a limited rate from the means providing fluid pressure to the associated booster; second conduit means connecting each of the boosters with the reservoir; a second plurality of flow rate control valves in the second conduit means, each being fluidly intermediate one of the boosters and the reservoir and each limiting the rate of fluid communication therebetween to a lesser extent than the associated flow rate control valve in the first conduit means and to a greater extent than the combined fluid communication through the normally open valve means and the associated flow rate control valve in the first conduit means; and a plurality of normally closed valve means in the second conduit means, each being fluidly intermediate one of the boosters and the reservoir and being individually cyclically shifted between the normal closed position and an open position during the sensed wheel lock condition whereby the pressure at the associated booster is cyclically reduced at a controlled rate through the flow rate control valve in the second conduit means and increased through the flow rate control valve in the first conduit means, the normally closed valve means remaining in the closed position when the wheel lock condition has been arrested and the normally open valve means being returned to the open position to reestablish unrestricted fluid communication between the means providing operating fluid and the booster.