Trailer brake control system

• US 3,897,979 A
• Filed: 07/15/1974
• Issued: 08/05/1975
• Est. Priority Date: 07/15/1974
• Status: Expired due to Term

• Current Assignee: Vangalis Dan P. ,
• Original Assignee: Dan P. Vangalis, George K. Burdick
• Inventors: Vangalis, Dan P., Burdick, George K.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/488,273
• Time in Patent Office: 386 Days
• Field of Search: 73/488,510,514 180/82R,100,103-104 188/3R,112,181A 200/52A,61.45R,61.31,61.52 303/7,20,21A,24A,24B,24BB 338/2,46 340/262
• US Class Current: 303/24.1
• CPC Class Codes: B60Q 1/44 for indicating braking action or preparation for braking, e.g. by detection of the foot approaching the brake pedal
• CPC Class Codes: B60T 13/74 with electrical assistance or drive
• CPC Class Codes: B60T 7/20 specially for trailers, e.g. in case of uncoupling of or overrunning by trailer inertia-actuated overrun brakes B60T13/08
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations
• CPC Class Codes: B60T 8/245 Longitudinal vehicle inclination
• CPC Class Codes: B60T 8/248 Trailer sway, e.g. for preventing jackknifing
• CPC Class Codes: B60T 8/323 Systems specially adapted for tractor-trailer combinations
• CPC Class Codes: B60T 8/74 sensing a rate of change of velocity

Abstract

A trailer brake control system which includes a housing having a sealed compartment filled with a damping liquid and a strain gauge decelerometer and inclinometer transducer mounted in the sealed compartment, the transducer including an elongated cantilevered flat spring having a weight on its free end, the spring having a narrowed width portion adjacent its fixed end, with matched strain gauges bonded on opposite sides of the narrowed width portion. The strain gauges are included as component arms of a bridge circuit which drives a high gain integrated circuit amplifier that in turn controls a transistorized circuit for controlling electric power supplied from the brake light circuits of the towing vehicle to the trailer as the spring bends through a small angle. The housing has mounting apparatus which provides for the orientation of the elongated flat spring in the plane normal to the longitudinal axis of the trailer, with the spring extending laterally of the trailer.

Claims

1. An inertial and gravitational sensitive trailer brake control system adapted to be electrically coupled between a vehicle having brake light circuits and a wheeled trailer towed by the vehicle for controlling electric power supplied from the vehicle to electrically actuated brakes on the trailer, comprising:

a housing orthogonal longitudinal, lateral and vertical axes and a forward end;

means for mounting the housing on the trailer or vehicle with its forward end facing forward thereon and with its longitudinal and lateral axes approximately parallel respectively to the longitudinal and wheel axes of the trailer or vehicle on which it is mounted;

said housing including a closed compartment filled with a damping liquid;

a decelerometer and inclinometer transducer mounted in the housing;

said transducer comprising an elongated flat spring mounted in the closed compartment as a cantilever and having a fixed end and a free end, a weight mounted on the free end of the spring, and means for detecting flexure of said spring in the forward direction of said housing;

the elongated flat spring being oriented so that it extends approximately parallel to the lateral axis of the housing in a plane approximately normal to the longitudinal axis of the housing;

solid state electrical means coupled to the decelerometer and inclinometer transducer and sensitive to the response thereof and to energization of the brake light circuits of the vehicle for exercising a control over the degree of electric power supplied from the vehicle to the trailer brakes;

means for electrically coupling the solid state electrical means to the brake light circuits of the vehicle; and

, means for electrically coupling the solid state electrical means to the trailer brakes.

2. The apparatus of claim 1 wherein the towing vehicle has left and right brake light circuits coupled to left and right turn signal circuits, and wherein the means for electrically coupling the solid state electrical means to the brake light circuits of the vehicle includes a pair of rectifiers, and means for electrically coupling the rectifiers respectively to the left and right brake light circuits of the vehicle.

3. An inertial and gravitational sensitive trailer brake control system adapted to be electrically coupled between a wheeled vehicle having brake light circuits and a wheeled trailer towed by the vehicle for controlling electric power supplied from the vehicle to electrically actuated brakes on the trailer, comprising:

a housing having orthogonal longitudinal, lateral and vertical axes and a forward end;

means for mounting the housing on the trailer or vehicle with its forward end facing forward thereon and with its longitudinal and lateral axes approximately parallel respectively to the longitudinal anD wheel axes of the trailer or vehicle on which it is mounted;

a strain gauge decelerometer and inclinometer transducer mounted in the housing and responsive on a continuously variable basis to forward deceleration and gravitational force components directed longitudinally of the housing;

means for substantially isolating the response of the strain gauge decelerometer and inclinometer transducer from acceleration components other than those directed longitudinally of the housing;

solid state electrical means coupled to the strain gauge decelerometer and inclinometer transducer and sensitive to the response thereof and to energization of the brake light circuits of the vehicle for exercising a control over the degree of electric power supplied from the vehicle to the trailer brakes;

means for electrically coupling the solid state electrical means to the brake light circuits of the vehicle; and

, means for electrically coupling the solid state electrical means to the trailer brakes.

4. The apparatus of claim 3 wherein the strain gauge decelerometer and inclinometer transducer comprises an elongated flat spring extending laterally of the housing in a plane approximately normal to the longitudinal axis of the housing, the spring having a fixed end and a free end with a weight thereon, the spring also having a narrowed portion near the fixed end thereof, and at least one strain gauge bonded to the narrowed portion of the spring.

5. The apparatus of claim 3 wherein the strain gauge decelerometer and the inclinometer transducer comprises an elongated flat spring disposed in a plane approximately normal to the longitudinal axis of the housing, the spring being in the form of a cantilever and having a fixed end and a free end with a weight thereon, the spring having a flat narrowed portion near the fixed end thereof, and a pair of matched strain gauges bonded on opposite sides of the flat narrowed portion of the spring.

6. The apparatus of claim 5 wherein the housing contains a closed compartment enclosing the strain gauge decelerometer and inclinometer transducer, said compartment being filled with a damping liquid.

7. The apparatus of claim 6 wherein the total angle through which the spring can bend is restricted by the confines of the compartment to an angle on the order of 10* or less.

8. The apparatus of claim 5 wherein the elongated flat spring extends approximately parallel to the lateral axis of the housing, hence laterally of the trailer or vehicle when the housing is mounted thereon.

9. The apparatus of claim 5 wherein the solid state electrical means comprises an electrical bridge circuit which electrically includes the strain gauges as component arms, a transistorized power control circuit for controlling electric power from the vehicle brake light circuits to the trailer brakes, and a direct coupled integrated circuit differential voltage amplifier coupling the bridge circuit to the power control circuit.

10. The apparatus of claim 9 wherein an adjustable potentiometer is mounted in an accessible position on the housing, and controls the supply voltage to the bridge circuit and amplifier.

11. The apparatus of claim 5 wherein the strain gauge decelerometer and inclinometer transducer provides its full range of response over a bending of the spring through an angle on the order of 10* or less.

12. In combination, a wheeled trailer having an electric brake system including electric brake coils and an electric power line running to the brake coils, the trailer having a longitudinal axis and a forward end;

and, an inertial and gravitational sensitive brake control device serially interposed in said electric power line, said brake control device comprising a housing having a closed compartment filled with a damping liquid, an elongated flat spring mounted as a cantilever in the closed compartment and having a free end with a weight affixed thereto, the elongated flat spring being oriented in a plane approximately normal to the longitudinal axis of the trailer with the spring extending laterally of the trailer approximately parallel to the wheel axes thereof, means for detecting flexure of the spring in the forward direction of the trailer, and solid state electrical means responsive to the detecting means and to the input of electrical power on said power line for varying the degree of electrical power supplied to said brake coils.

13. The apparatus of claim 12 wherein the spring has a narrowed width portion near its fixed end, and the detecting means comprises a pair of matched strain gauges bonded on opposite sides of the narrowed width portion of the spring.

14. The apparatus of claim 13 wherein the confines of the housing compartment limits bending of the spring to an angle on the order of 4* or less.