US 4,072,011 A · Hydraulic brake booster

Abstract

A brake booster for use in a braking system having a control valve which is responsive to a hydraulic output force created by manually moving a piston in a bore of a master cylinder. The hydraulic output force actuates the control valve which proportionally directs a portion of the fluid output of a pump which supplies a power steering gear with hydraulic fluid, into the bore. This portion of the output of the pump acts on the piston and provides an auxiliary force for moving the piston through which the hydraulic output force is created. When the hydraulic output force of the brake booster reaches a predetermined value, the control valve engages a stop member to limit the diversion of the fluid output from the pump and thereby assure that a minimal quantity of the fluid output is continually available to operate the power steering gear.

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Drawings

Claims9

Dependent claims

A combined wheel brake actuator and power steering mechanism for a vehicle comprising:

a housing having a first bore, a second bore and a third bore located therein;
a first piston located in said first bore for establishing a first pressurizing chamber and a power chamber therein;
a second piston located in said first bore for establishing a second pressurizing chamber therein;
a first plunger located in said second bore for establishing a first flow through chamber, a distribution chamber and a control chamber, said first flow through chamber being connected to said first pressurizing chamber by a first passage and to a first outlet port, said first outlet port being connected by a first conduit to a first set of wheel brakes on the vehicle, said distribution chamber being connected to said power chamber by a distribution passage and to a reservoir by a relief conduit, said control chamber being connected by a first supply conduit to receive the fluid output of a pump and to said third bore through a second supply conduit;
a second plunger located in said second bore for establishing a second flow through chamber therein, said second flow through chamber being connected to said second pressurizing chamber by a second passage and to a second outlet port, said second outlet port being connected by a second conduit to a second set of wheel brakes on the vehicle;
resilient means located in said second bore for urging said first plunger into engagement with said second plunger to permit the fluid output of the pump to freely flow through said control chamber;
a rotary valve located in said third bore for controlling the communication of the fluid output of the pump in said second supply conduit to a steering gear in response to an operator steering input to aid in turning the wheels of the vehicle, said third bore being connected to said relief conduit by a relief passage to permit the fluid output in the third bore to be returned to the reservoir of the pump;
actuator means responsive to an operator brake input force for moving said first piston to create a first fluid actuation pressure in said first pressurizing chamber, said first fluid actuation pressure being communicated through said first passage, said first flow through chamber, said first outlet port, and said first conduit to initiate operation of said first set of wheel brakes, said first fluid actuation pressure in said first flow through chamber moving said first plunger in opposition to said resilient means to interrupt communication between said distribution chamber and said relief passage and thereafter restrict the flow of the fluid output of the pump through the control chamber and proportionally allow a portion of the fluid output of the pump in the control chamber to flow into said distribution chamber for communication to said power chamber, said portion of the fluid output of the pump in the power chamber acting on said first piston to provide an auxiliary input force for moving said first piston in the first pressurizing chamber to create an operational brake fluid pressure;
and
stop means located in said second bore for limiting the movement of said first plunger and correspondingly that portion of the fluid output of the pump diverted from said control chamber to assure that minimal fluid output from the pump is continually available to operate said steering gear.

7 more elements

Dependencies are inferred from the claim text.

Description3,711 words

Summary820 words

#Hydraulic power brake boosters have been proposed as a replacement for pneumatic power brake boosters because of a reduction in available space under the hoods of some vehicles. In an effort to provide a uniform braking force corresponding to an operator input force, a hydraulic ratio changer as disclosed in U.S. Pat. No. 3,831,491 was introduced into such brake boosters. Unfortunately, in these hydraulic ratio changers, the change in movement of the input pedal varies with the change in volume of a hydraulic fluid in the control chamber. In an effort to compensate for volumetric change of the fluid in the control chamber, fluid communication with a reservoir is established when the input force from the operator terminates. Unfortunately, such compensation is dependent upon the position of an actuation member and not the pressure producing piston.

#The hydraulic brake booster in U.S. Pat. No. 3,838,629 discloses a manually operated ratio changer having a plunger which pressurizes fluid in a closed chamber whenever an input force is applied to the boost operating mechanism. The pressurized fluid is communicated to a spool valve which in turn controls the communication of hydraulic fluid under pressure. The hydraulic fluid under pressure moves a piston in a master cylinder and provides an energizing force for operating the wheel brakes in a vehicle.

#I have devised a hydraulic brake booster means having a control valve which is activated by an operational output force created through the movement of a piston means in a bore by a manual input force. The control valve diverts a portion of the output of a hydraulic pump into the bore which acts on the piston means to provide an auxiliary force through which the operational output is created.

Brief description of the drawings3 figures

#FIG. 1 is a schematic view of a common fluid hydraulic braking and steering system for use in a vehicle, showing a broken sectional view of a brake booster incorporating the teachings of my invention;

#FIG. 2 is a sectional view of a second control means for use with the brake booster of FIG. 1; and

#FIG. 3 is a schematic view of a two-fluid hydraulic braking and steering system for use in a vehicle, showing a broken sectional view of a brake booster incorporating the teachings of my invention.

Detailed description2,801 words

#The common fluid hydraulic braking and steering systems 10, shown in FIG. 1, has a brake booster means 12 integrally located in a common housing 14 with a power steering gear 16. The brake booster means 12 is connected to the front wheel brakes 18 and to the rear wheel brakes 20 through a valve means 22 located in the housing 14. Similarly, the power steering gear 16 is connected to an engine driven pump means 24 through the valve means 22. The valve means 22 responds to the output of the brake booster means 12 for diverting a portion of the output of the pump means 24 into the brake booster means 12 to thereby provide an auxiliary force for operating the brake booster means 12.

#In more particular detail, the brake booster means 12 includes a bore 26 located in the housing 14. The bore 26 is divided into a first pressurizing chamber 30 by a first piston 34 and a second pressurizing chamber 36 by a second piston 38. A projection 40 holds the first piston 34 away from the first end 42 of the bore 26 to establish a power chamber 32. A seal 44 located in groove 46 in the first piston 34 separates the first pressurizing chamber 30 from the power chamber 32.

#A return spring 48 located in the second pressurizing chamber 36 acts through the second piston 38 and actuation spring 50 to urge the projection 40 on the first piston 34 against the first end 42 of the housing 14.

Hydraulic brake booster

Life of this patent

Hydraulic brake booster

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims9

Description3,711 words

Drawings

Classification2 codes

Life of this patent

Description3,711 words