Electronic brake monitoring system and method

• US 4,937,554 A
• Filed: 05/22/1989
• Issued: 06/26/1990
• Est. Priority Date: 05/22/1989
• Status: Expired due to Fees

• Current Assignee: PACCAR Incorporated
• Original Assignee: PACCAR Incorporated
• Inventors: Herman, Mark N.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/355,687
• Time in Patent Office: 400 Days
• Field of Search: 73/121, 73/129, 73/132, 116/28 R, 188/1.11, 188/, 340/453, 340/454
• US Class Current: 340/453
• 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 13/66 Electrical control in fluid-pressure brake systems
• CPC Class Codes: B60T 17/22 Devices for monitoring or checking brake systems; Signal devices
• CPC Class Codes: F16D 65/52 self-acting in one direction for adjusting excessive play
• CPC Class Codes: F16D 65/60 for angular adjustment of two concentric parts of the brake control systems
• CPC Class Codes: F16D 66/025 sensing the position of parts of the brake system other than the braking members, e.g. limit switches mounted on master cylinders

Abstract

A brake monitoring system for a motorized vehicle having fluid brakes including a pressurized fluid chamber and brake engaging apparatus. Sensors are provided to measure the required fluid pressure exerted by the fluid chamber on the engaging apparatus to bring about braking of the vehicle. Measurement is also made of the distance the engaging apparatus is extended from the fluid chamber in braking. Apparatus is further provided to determine from the measured fluid pressure and measured engaging distance whether the brakes are properly adjusted.

Claims

1. In a braking system for a motorized vehicle having at least one fluid brake including a brake engaging means and a pressurized fluid chamber exerting fluid pressure on said engaging means to cause the engaging means to extend forward upon actuation of a brake pedal in order to exert pressure on a braking means that is connected to the engaging means, the improvement comprising:

means for sensing the fluid pressure exerted by the fluid chamber on the engaging means in order to cause the engaging means to extend forward toward the braking means;

means for measuring the distance the engaging member is extended from the fluid chamber toward the braking means; and

means for determining from said sensed fluid pressure and said measured engaging means distance the adjustment status of said fluid brake.

2. The braking system of claim 1 wherein the fluid pressure sensing means comprises a fluid pressure transducer which creates an electrical signal proportional to the amount of fluid pressure being supplied to the fluid chamber.

3. The braking system on claim 2 wherein the distance measuring means comprises an electromagnetic sensor for measuring the distance the engaging means has travelled by measuring the displacement in the braking means, said distance measuring means creating an electrical signal proportional to the distance the engaging means is extended from the fluid chamber.

4. The braking system of claim 3 wherein the determining means comprises a microprocessor having a table of corresponding fluid pressures and engaging means distances, said microprocessor determining from said table brake adjustment status based on a corresponding measurement of fluid pressure and engaging means distance.

5. A braking system for a motorized vehicle having at least one fluid brake including a pressurized fluid chamber which extends a pushrod that exerts pressure on a slack adjuster activating a braking means that is connected to the slack adjustor, comprising:

means for sensing the fluid pressure exerted by the fluid chamber on said pushrod causing said pushrod to be extended toward the slack adjuster;

means for measuring the distance the pushrod is extended from said fluid chamber toward said slack adjustor, moving said slack adjuster by a like amount; and

means for determining from said sensed fluid pressure and measured pushrod distance whether said brake is out of adjustment.

6. The braking system of claim 5 wherein the fluid pressure sensing means comprises a fluid pressure transducer which creates an electrical signal proportional to the amount of fluid pressure being supplied to the fluid chamber.

7. The braking system on claim 6 wherein the distance measuring means comprises an electromagnetic sensor for measuring the distance the pushrod has travelled by measuring the displacement in the slack adjuster, said distance measuring means creating an electrical signal proportional to the distance the pushrod is extended from the fluid chamber.

8. The braking system of claim 7 wherein the determining means comprises a microprocessor.

9. The braking system of claim 7 wherein the determining means further comprises:

means for converting the proportional electrical signals from the sensing means and the measuring means into digital signals;

means for tabulating the digital fluid pressure signal along one axis of a table in increasing order;

means for tabulating the digital pushrod distance along another axis of the table in increasing order; and

means for determining for each corresponding measurement of fluid pressure and pushrod distance in the table whether the brake is adjusted.

10. The braking system of claim 5 wherein the fluid is air.

11. An electronic braking system for a motorized vehicle having air brakes, the air brakes including a pressurized air chamber having a pushrod which exerts pressure on a slack adjuster turning the slack adjuster which is connected to a braking member, whereby the braking member is placed in contact with a brake drum causing the motorized vehicle to brake, comprising:

means for sensing the air pressure exerted by the air chamber on the pushrod to extend the pushrod;

means for measuring the distance the pushrod is extended from the air chamber;

means for tabulating said sensed air pressure and measured pushrod distance; and

means for determining from said tabulation whether the air brakes are out of adjustment.

12. A method of braking for a motorized vehicle having at least one fluid brake including a pressurized fluid chamber having an engaging means which exerts pressure on a braking means that is connected to the engaging means, whereby brake shoes of the braking means are placed in contact with a brake drum causing the motorized vehicle to brake, comprising the steps of:

sensing the fluid pressure exerted by the fluid chamber on the engaging means causing the engaging means to be extended toward the braking means;

measuring the distance the engaging member is extended from the fluid chamber toward the braking means; and

determining from said sensed fluid pressure and measured engaging means distance whether the brake is out of adjustment.

13. The method of braking of claim 12 wherein the step of fluid pressure sensing comprises the step of providing a fluid pressure transducer which creates an electrical signal proportional to the amount of fluid pressure being supplied to the fluid chamber.

14. The method of braking of claim 13 wherein the step of distance measuring comprises the step of providing an electromagnetic sensor for measuring the distance the engaging means has travelled, said distance measuring means creating an electrical signal proportional to the distance the engaging means is extended from the fluid chamber.

15. The method of braking of claim 14 wherein the step of determining comprises the steps of tabulating the fluid pressure signal and the engaging means distance signal and designating for each corresponding measurement of fluid pressure and engaging means distance in the table whether the brake is adjusted.