Automatic brake actuator with controlled release

• US 4,608,825 A
• Filed: 10/07/1983
• Issued: 09/02/1986
• Est. Priority Date: 10/07/1983
• Status: Expired due to Fees

• Current Assignee: New Products Development Group, Inc.
• Original Assignee: Fail Safe Brake Corporation
• Inventors: Fontaine, William G.
• Primary Examiner(s): Love, John J.
• Assistant Examiner(s): CULBRETH, ERIC D
• Application Number:
  US06/540,060
• Time in Patent Office: 1,061 Days
• Field of Search: 60/376, 60/547.1, 60/582, 60/545, 60/550, 60/560, 91/509, 91/510, 91/519, 188/109, 188/353, 303/18, 303/19, 180/272, 180/273, 180/278
• US Class Current: 60/545
• CPC Class Codes: B60T 13/72 in vacuum systems or vacuum booster units
• CPC Class Codes: B60T 7/12 for automatic initiation; for initiation not subject to will of driver or passenger limiting speed of vehicles other than rail vehicles B60K31/00

Abstract

An automatic brake actuator for motor vehicles which operates to activate the vehicle brakes at a predetermined rate and at a predetermined amount of force in predetermined conditions. In a particular embodiment, the brake actuator is controlled by an electrical control system which includes a switch in the driver'"'"'s seat that automatically senses the weight of the driver when seated. The brake actuator may be connected to the vehicle'"'"'s vacuum brake system and may be combined therewith by means of a unique electrically operated air control valve that is inserted in the vacuum brake air path. An additional electrically operated constraining air valve may be provided which insures that the brake actuator is activated gradually at (a predetermined rate) in order to avoid sudden hazardous stopping of the vehicle. The brake actuator control may include access to other vehicle functions such as theft alarm, etc. to prevent unwanted operation of the vehicle. The control circuit includes provision for maintaining the brakes activated after the driver re-enters the vehicle and until he operates the accelerator pedal or corrects the problems activating the system (low oil pressure, engine overheating, anti-theft or other conditions) that would allow the vehicle to move forward or backwards again.

Claims

1. In a brake system for a motor vehicle having a brake, said brake system comprising:

a brake pedal operable in one direction to apply the brake;

a reciprocable brake shaft operated by said brake pedal;

a vacuum operated booster for said brake comprising a housing having a variable pressure chamber therein, a movable wall extending transversely across the interior of said housing on one side of said variable pressure chamber, and means for connecting said variable pressure chamber to a source of vacuum, said movable wall having an annular extension on the opposite side from said variable pressure chamber slidably supported on said housing and receiving said brake shaft reciprocably, and said movable wall having an air passageway providing fluid communication between said variable pressure chamber on said one side of the movable wall and the interior of said annular extension on the opposite side;

and flow restriction means on said brake shaft inside said annular extension for restricting the flow of air from the interior of said annular extension into said air passageway in said movable wall upon displacement of the brake shaft by the brake pedal toward said movable wall;

the improvement wherein;

said brake shaft has a passageway therein for providing fluid communication between the interior of said annular extension and the atmosphere, said brake shaft passageway defining a valve seat;

a magnetic valve member in said brake shaft passageway engageable with said valve seat to block fluid communication between the interior of said annular extension and the atmosphere;

spring means biaaing said valve member into engagement with said valve seat;

and a solenoid coil inductively coupled to said valve member for unseating said valve member from said seat in response to energization of the coil, whereby to connect said variable pressure chamber to the atmosphere through said air passageway in said movable wall and said annular extension.

2. A brake system according to claim 1, wherein:

said valve member is a plunger slidably reciprocable in said brake shaft passageway and having a plurality of longitudinal grooves therein;

and said brake shaft has an interior wall extending transverse to said plunger and providing said valve seat for engagement by the adjacent end of the plunger to block said grooves in the plunger.

3. A brake system according to claim 2, wherein:

said solenoid coil encircles said brake shaft, is slidably received in said annular extension and is rigidly coupled to said brake shaft for movement in unison therewith.

4. A brake system according to claim 3, wherein:

said passageway in the brake shaft is on the opposite side of said flow restriction means from said air passageway in said movable wall.

5. A brake system according to claim 1, wherein:

said passageway in the brake shaft is on the opposite side of said flow restriction means from said air passageway in said movable wall.

6. A brake system according to claim 1, wherein:

said solenoid coil encircles said brake shaft and is slidably received in said annular extension and is rigidly coupled to said brake shaft for movement in unison therewith.