ANTI-SKID VEHICLE BRAKING SYSTEM

• US 3,771,840 A
• Filed: 07/12/1971
• Issued: 11/13/1973
• Est. Priority Date: 07/12/1971
• Status: Expired due to Term

• Current Assignee: Harold C. Hubbard
• Original Assignee: Harold C. Hubbard
• Inventors: Hubbard, Harold C.
• Primary Examiner(s): Buchler, Milton
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/161,885
• Time in Patent Office: 855 Days
• Field of Search: 180/82 188/3R,163,181C 192/3H 200/61.45 244/8B,111 303/7,20,21,89 317/5 318/52 324/160,161 340/263
• US Class Current: 303/176
• CPC Class Codes: B60T 8/323 Systems specially adapted for tractor-trailer combinations
• CPC Class Codes: B60T 8/327 Pneumatic systems
• CPC Class Codes: B60T 8/96 on speed responsive control means
• CPC Class Codes: G01P 1/10 for indicating predetermined speeds
• CPC Class Codes: Y10S 188/02 Hill holder
• CPC Class Codes: Y10S 303/08 Antichatter

Abstract

A non-skid brake control system for vehicles, particularly towed vehicles having electrically, pneumatically and/or hydraulically operated brakes controlled from the towing vehicle. A pair of braked wheels of the towed vehicle, one on each side of the vehicle, each have a speed sensing switch to sense the rate of rotation of the associated braked trailer wheel so as to provide anti-skid modulation to the associated brake when differential braking occurs between these braked wheels. The system automatically disables the anti-skid modulation when the vehicle speed is below an adjustable predetermined speed to thereby provide full braking effort under static, hill-holding or low speed conditions. Wheel speed sensing switch constructions are employed which utilize reed switches magnetically actuated by a permanent magnet carried on a centrifugally actuated flyweight mechanism. The anti-skid system may be further modulated by a vehicle speed sensing switch to prevent dual wheel lock-up above a given vehicle speed.

Claims

1. An electrically controlled brake system for a vehicle having left and right electrically braked wheels, first and second direct circuit means for respectively supplying braking current directly to said left and right wheel brakes, first and second crossover circuit means in shunt with said second and first direct circuit means respectively for respectively supplying braking current to said left and right wheel brakes, first and second wheel speed sensing means for sensing the rotational velocity of said left and right wheels respectively and means operably coupling said first and second wheel speed sensing means to said first and second direct and crossover circuit means respectively whereby:

a. when the rotational velocity of said left wheel is below a given low speed said first direct circuit means is open and said second crossover circuit is closed;

b. when the rotational velocity of said left wheel is above said given speed said first direct circuit means is closed and said first crossover circuit is open;

c. when the rotational velocity of said right wheel is below said given speed said second direct circuit means is open and said first crossover circuit is closed; and

d. when the rotational velocity of said right wheel is above said given speed said second direct circuit means is closed and said first crossover circuit is open.

2. The system as set forth in claim 1 further including easy-on circuit means compriSing a limiting resistor in common series circuit with said direct and crossover circuit means, a shunt means across said limiting resistor and time delay means for closing said shunt means after a predetermined time delay initiated by connecting a source of braking current across said direct and crossover circuit means.

3. The system as set forth in claim 1 wherein each of said crossover circuits includes a pair of normally open relay contacts in series circuit therein, a relay coil for actuating said contacts simultaneously, relay energizing circuit means for energizing said relay coil in response to application of a source of braking current across said direct circuit means, and time delay means in said relay energizing circuit means for delaying energization of said relay coil for a predetermined time from said application of the source of braking current to a time correlated with the time required to reaccelerate the associated braked wheel to said given wheel after the braking current applied thereto has been reduced by opening of the associated direct circuit means.

4. In an anti-skid electric brake system for a vehicle having right and left wheel electric brakes actuated by applying a source of braking current across a current responsive element in each brake, the imrpovement comprising:

a. direct and crossover left brake energizing circuits connected across said left wheel brake and said source, b. direct and crossover right brake energizing circuits connected across said right wheel brake and said source, c. left and right wheel speed sensing switches respectively associated with said left and right wheels and operable to close above a given rotational speed of the associated wheel and to open below said speed, d. left and right wheel relay circuits connected across said source and each having a coil energized by closure of the associated left and right sensing switches and de-energized by opening of the associated sensing switch, e. normally closed contacts in said right wheel crossover circuit and normally open contacts in said left wheel direct circuit operable to be respectively opened and closed by energization of said left wheel relay coil, and f. normally closed contacts in said left wheel crossover circuit and normally open contacts in said right wheel direct circuit operable to be respectively opened and closed by energization of said right wheel relay coil, and g. control means in common series circuit with said direct, crossover and relay circuits across said source of braking current for disconnecting said circuits from said source.

5. An electrically controlled brake system for a vehicle having left and right electrically controlled and pneumatically braked wheels, first and second direct circuit means for respectively supplying brake releasing current directly to said left and right wheel brakes, first and second crossover circuit means in shunt with said first and second direct circuit means respectively supplying brake releasing current to said left and right wheel brakes, first and second wheel speed sensing means for sensing the rotational velocity of said left and right wheels respectively and means operably coupling said first and second wheel speed sensing means to said first and second direct and crossover circuit means respectively whereby:

a. when the rotational velocity of said left wheel is below a given low speed siad first direct circuit means is closed and said second crossover circuit is closed;

b. when the rotational velocity of said left wheel is above said given speed said first direct circuit means is open and said second crossover circuit is open;

c. when the rotational velocity of said right wheel is below said given speed said second direct circuit means is closed and said first crossover circuit is closed; and

d. when the rotational velocity of said right wheel is above said given speed said second direct circuit means is open and said first crossover circuit iS open.

6. The system as set forth in claim 5 further including time delay circuit means in shunt circuit with said direct and crossover circuit means, contact means in common series circuit with said first and second crossover circuit means and operably controlled by said time delay means for opening said first and second crossover circuit means after a predetermined time delay initiated by connecting a source of brake releasing current across said direct and crossover circuit means.

7. The system as set forth in claim 5 wherein each of said crossover circuits includes a set of normally closed relay contacts in series circuit therein, a relay coil for actuating said contacts, relay energizing circuit means for energizing said relay coil in response to application of a source of brake releasing current across said direct circuit means, and time delay means in said relay energizing circuit means for delaying energization of said relay coil for a predetermined time after said application of the source of brake releasing current, said predetermined time being correlated with the time period required to reaccelerate the associated brake wheel to said given speed after the brake releasing current applied via the associated direct circuit means has been reduced by the associated wheel speed sensing means causing opening of the associated direct circuit means.

8. In an anti-skid brake system for a vehicle having right and left wheel electrically controlled brakes actuated by controlling the application of a source of brake controlling current across a current responsive element in a control means for each brake, the improvement comprising:

a. direct and crossover left brake actuating circuits connected across said left wheel brake control means and said source, b. direct and crossover right brake actuating circuits connected across said right wheel brake control means and said source, c. left and right wheel speed sensing switches respectively associated with said left and right wheels and operable to actuate to a first state above a given rotational speed of the associated wheel and to actuate to a second state below said speed, d. left and right wheel relay circuits connected across said source and each having a coil energized by the first state condition of the associated left and right sensing switches and deenergized by the second state condition of the associated sensing switch, e. normally closed contacts in said right wheel crossover circuit and normally open contacts in said left wheel direct circuit operable to be respectively opened and closed by energization of said left wheel relay coil, f. normally closed contacts in said left wheel crossover circuit and normally open contacts in said right wheel direct circuit operable to be respectively opened and closed by energizaion of said right wheel relay coil, and g. control means in common series circuit with said direct, crossover and relay circuits across said source of braking current for disconnecting said circuits from said source.

9. In an anti-skid brake system for a vehicle having right and left wheel electrically controlled brakes actuated by controlling the application of a source of brake controlling current across a current responsive element in a control means for each brake, the improvement comprising:

a. direct and crossover left brake actuating circuits connected across said left wheel brake control means and said source, b. direct and crossover right brake actuating circuits connected across said right wheel brake control means and said source, c. left and right wheel speed sensing switches respectively associated with said left and right wheels and operable to actuate to a first state above a given rotational speed of the associated wheel and to actuate to a second state below said speed, d. left and right wheel relay circuits connected across said source and each actuated between first and second conditions by the first and second state cOnditions respectively, of the associated left and right sensing switches, e. a first set of contacts in said right wheel crossover circuit and a second set of contacts in said left wheel direct circuit operable to be respectively actuated to opposite state conditions by actuation of said left wheel relay coil, f. a third set of contacts in said left wheel crossover circuit and a fourth set of contacts in said right wheel direct circuit operable to be respectively actuated to opposite state conditions by actuation of said right wheel relay coil, and, g. control means in common series circuit with said direct, crossover and relay circuits across said source of braking current for disconnecting said circuits from said source.

10. In an anti-skid control for the brake system of a vehicle having left and right hand road wheels and left and right brake mechanisms respectively associated therewith energized from a source of an actuating medium by controlling the flow of the actuating medium to said brake mechanism, the combination comprising firt and second means for conducting said medium from the source to said left and right brake mechanisms respectively, first and second means for sensing the rotational velocity of said left and right wheels respectively, first and second electrical control circuit means for controlling flow of the medium through said conducting means to vary the braking force developed by said left and right brake mechanisms respectively, first and second control means in said first and second control circuit means respectively operably connected respectively to said first and second wheel velocity sensing means to cause the braking medium supplied to the brake mechanism of the associated wheel to be reduced when such wheel drops below a given rotational velocity to thereby effect anti-skid modulation of such wheel, and disabling circuit means responsive to vehicle speed for rendering said anti-skid modulation of said flow controlling circuit means ineffective when the road speed of said vehicle drops below a given value, said disabling circuit means comprising first and second crossover circuits for conducting said medium from said first conducting means to said right brake mechanism and from said second conducting means to said left brake mechanism, and third and fourth control means enabling conduction of the medium through said first and second crossover networks respectively in response to actuation of said first and second control means respectively to a flow reducing state.

11. In an anti-skid control for the brake system of a vehicle having left and right hand road wheels and left and right brake mechanisms respectively associated therewith energized from a source of an actuating mechanism by controlling the flow of the actuating medium to said brake mechanism, the combination comprising first and second means for conducting said medium from the source to said left and right brake mechanisms respectively, first and second means for sensing the rotational velocity of said left and right wheels respectively, first and second electrical control circuit means for controlling flow of the medium through said conducting means to vary the braking force developed by said left and right brake mechanisms respectively, first and second control means in said first and second control circuit means respectively operably connected respectively to said first and second wheel velocity sensing means to cause the braking medium supplied to the brake mechanism of the associated wheel to be reduced when such wheel drops below a given rotational velocity to thereby effect anti-skid modulation of such wheel, and disabling circuit means responsive to vehicle speed for rendering said anti-skid modulation of said flow controlling circuit means ineffective when the road speed of said vehicle drops below a given value, said first and second wheel velocity sensing means respectively comprising first and second reed switch means mounted on said vehicle, firsT and second electrical circuit means coupled across said first and second reed switch means and operably connected to the associated first and second control circuit means, first and second permanent magnet means mounted on said vehicle for closing and opening said first and second reed switch means respectively, and first and second centrifugally actuated means responsive to the rotational velocity of the associated left and right wheel respectively to vary the position of said first and second magnet means relative to said first and second reed switch means respectively such that said first and second reed switch means are respectively actuated when the rotational speed of the associated wheel varies through said given rotational velocity.

12. The system as set forth in claim 11 wherein said disabling circuit means comprises a switch coupled to the vehicle speedometer and including brush strip means operably connected in controlling relationship to said control circuit means such that said switch enables operation of said control circuit means in a range from a low vehicle speed up to a maximum vehicle speed and disables operation of said control circuit means in a range from said low speed to zero vehicle speed.

13. The system as set forth in claim 11 wherein each of said first and second reed switch means comprises first and second reed switches each having a pair of reeds with their free ends overlapped in a zone coincident with the axis of rotation of their associated wheel, said first and second reed switches being mounted with respect to each other and the wheel such that the longitudinal axes of said first and second switches are generally perpendicular to each other and to said axis of rotation of their associated wheel.

14. The system as set forth in claim 11 wherein each of said first and second reed switch means comprises a reed switch having a pair of reeds extending with their longitudinal dimensions in generally coaxial relation with the axis of rotation of their associated wheel.

15. In an anti-skid control for the brake system of a vehicle having left and right hand road wheels and left and right pressure fluid actuated brake mechanisms respectively associated therewith energized from a source of a pressure fluid by controlling the flow of the pressure fluid to said brake mechanism, the combination comprising first and second means for conducting said fluid from the source to said left and right brake mechanisms respectively to apply fluid pressure thereto, first and second means for sensing the rotational velocity of said left and right wheels respectively, first and second electrical control circuit means for controlling flow of the fluid through said conducting means to vary the braking force developed by said left and right brake mechanisms respectively, first and second control means in said first and second control circuit means respectively operably connected respectively to said first and second wheel velocity sensing means to cause the braking fluid pressure applied to the brake mechanism of the associated wheel to be released when such wheel drops below a given rotational velocity to thereby effect anti-skid modulation of such wheel, and disabling circuit means responsive to vehicle speed for rendering said anti-skid modulation of said flow controlling circuit means ineffective when the road speed of said vehicle drops below a given value, said disabling circuit means comprising first and second crossover circuits for respectively operably connecting said first control circuit means to said second control means and said second control circuit means to said first control means, and third and fourth control means for operably connecting said first and second crossover networks in shunt relationship with said first and second control means respectively in response to actuation of said first and second control means respectively to a fluid pressure releasing state.

16. The system as set forth in claim 15 wherein said first and second wheel veLocity sensing means respectively comprise first and second reed switch means mounted on said vehicle, first and second electrical circuit means coupled across said first and second reed switch means and operably connected to the associated first and second control circuit means, first and second permanent magnet means mounted on said vehicle for closing and opening said first and second reed switch means respectively, and first and second centrifugally actuated means responsive to the rotational velocity of the associated left and right wheel respectively to vary the position of said first and second magnet means relative to second first and second reed switch means respectively such that said first and second reed switch means are respectively actuated when the rotational speed of the associated wheel varies through said given rotational velocity.

17. The system as set forth in claim 16 wherein each of said first and second reed switch means comprise first and second reed switches each having a pair of reeds with their free ends overlapped in a zone coincident with the axis of rotation of their associated wheel, said first and second reed switches being mounted with respect to each other and the wheel such that the longitudinal axes of said first and second switches are generally perpendicular to each other and to said axis of rotation of the wheel.

18. The system as set forth in claim 16 wherein each of said first and second reed switch means comprises a reed switch having a pair of reeds extending generally longitudinally and being mounted in generally coaxial relation with the axis of rotation on their associated wheel.