The hydraulic brake booster (12) includes a resilient member (96) disposed between an input member (94, 194, 294) and a pair of valve members (98, 101; 112) which control fluid pressure flow from an accumulator (14) When the input member (94, 194, 294) is actuated by the vehicle operator, theresilient member (96) is compressed so that the input member (94, 194, 294) moves relative to the valve members (98, 101; 112) and thus provides for greater movement of the input member (94, 194, 294) than for the valve members (98, 101; 112) The booster (12) includes a hydraulic or mechanical lockout which, in the absence of fluid pressure from the accumulator (14), eliminates the movement of the input member (94, 194, 294) relative to the valve members (98, 101; 112) so that the relative movement eliminated is not added to the valve stroke during manual operation of the booster (12)

Hydraulic brake booster

A booster for a vehicle braking system has an input piston, a boost piston and an output piston working a bore, the boost piston being advanced in the bore in response to pressure fluid from a source pressurizing a boost chamber under control of a valve. The operation of the valve is dependent on the pressure in the system, and the valve has a valve mechanism working in a bore in the boost piston of which one part has a pressure-responsive face, the valve being operative, on initial movement of the input piston to cause pressurization of the braking system to the threshold level, and application of pressure fluid to the pressure-responsive face to move the part relative to the input piston to place the boost chamber in communication with the pressure source. Threshold pressurization of the braking system may be achieved by pressurization of the boost chamber, or an auxiliary chamber forward of the boost piston to a predetermined level.

Power-operated boosters

In order to stabilize the line pressure developed by a line pressure regulator valve and simultaneously control the operation of a variable capacity pump in a manner that the latter exhibits the desired degree of response to changes in the line pressure, a flow restriction is defined in the bore of the valve itself. This flow restriction is defined between the wall of the bore in which the spool is disposed and a portion of the spool which extends between two adjacent lands and which has a diameter which is slightly smaller than that of the bore.

Regulator valve for hydraulic control system including variable displacement pump

An air management system is described for removing and reintroducing a desired amount of air into an air passage of a pressure measurement catheter. More specifically, the system includes a cylindrical housing, check valves in communication with the housing and an moveable shaft with multiple sealing members along its length. As the shaft is moved within the housing, a piston member causes the residual air in the catheter air passage to be evacuated to a defined negative pressure. Further movement of the shaft causes a piston member to inject a predetermined volume of air into the catheter air passage. In this respect, periodic adjustments of the piston member returns the volume of air in a variable volume chamber to one that is unaffected by residual volume in the chamber and that provides an optimum volume of air to maximize the time the sensor can function accurately between recharging events.

Catheter air management system

A hydraulic brake booster includes a booster piston axially slidable in a bore of a housing and delimiting therein a boosting compartment, and a brake pedal responsive operating element which partially extends into the boosting compartment to act as a plunger therein. A control valve has a valve body which is stationary relative to the housing and a valve member which is slidably received in the valve body and controls communication of a pressure chamber with sources of control fluid at reference pressure and at control pressure, the pressure in the boosting compartment being proportionate to the pressure in the pressure chamber. A flexible elongated tubular element equidistantly interconnects the valve body with the booster piston, and an elastic body of substantially constant length, such as a cable, elastic rod, or a body of incompressible liquid, which is at least partially received in the tubular element, converts the displacement of the operating element relative to the booster piston into movement of the valve member relative to the valve body and thus controls the pressure in the boosting compartment. The pressure chamber may be filled with liquid and directly be connected with the boosting compartment, or it may be constituted by one of the two chambers of a vacuum booster having a movable wall separating the two chambers from one another and connected to a piston received in a bore containing boosting liquid and communicating with the boosting compartment.

A hydraulic power brake unit including a power piston operatively engaging a conventional master cylinder and an annular valve spool having differential end areas communicating with the power chamber formed by the power piston and being normally positioned in the housing to communicate hydraulic fluid from a pressure source to the power steering unit and communicate the power chamber to the power source reservoir. When the brake pedal is actuated, an actuating spring acting between the valve spool and a reaction piston attached to the pedal pushrod is compressed and the valve spool is moved to restrict fluid communication from the pressure source to the power steering unit and divert the flow to the power chamber while simultaneously blocking communication of the power chamber to the reservoir so that the power chamber is pressurized and the power piston fluidly displaced to actuate the master cylinder. The power chamber pressure acts on the differential area of the valve spool to resist its movement by the actuating spring and causes it to function as a regulating valve which continuously provides a power chamber pressure proportional to the force of the actuating spring. Upon a malfunction caused loss of hydraulic pressure the reaction piston moves into abutting engagement with the power piston to provide a rigid force transmitting link between the pushrod and the master cylinder whereby the brakes are actuated independently of the hydraulic boost.

D Flory

Papers

Hydraulic power brake unit