Brake Diagnostic Computer

An Appendix to this patent application, comprising six sheets of computer program listings illustrating a preferred embodiment of the computer software code contemplated by the invention disclosed herein is appended hereto.

This invention relates to a method and device for throughly testing the braking system of a vehicle so as to identify any deficiency in performance of the brake system and also identify the cause of such deficiency so that such deficiency may be repaired and the cause eliminated.

Heretofore, brakes were customarily tested in a shop on a roller/torque device wherein the vehicle's wheels were placed on a pair of rollers driven by a torque motor that drives the wheels at a constant speed. While the wheels are turning, the vehicle brakes are applied and the magnitude of the torque drive required to rotate the rollers is then measured. Such measurement gives a measurement of the vehicle's brake force and thus an indication of brake performance. Such tests were often augmented, especially if brake performance was low, by a visual inspection of the vehicle's brakes which involves removal of the wheel and visual examination of the brake parts.

The prior methods were highly subjective and the results varied as to whether operation was within normal limits based upon the mechanic's interpretation of the appearance. The variety of results were primarily due to the failure of the test as most methods of brake testing are less than a scientific diagnosis of brake related problems. The methods that are now common practice in the automotive repair aftermarket are far from complete or accurate.

To properly inspect a brake system on today's vehicles, technicians must follow a flow chart, or a specific step by step procedure to determine the exact condition of each components in the brake system. Because most technicians do a quick manual inspection of the vehicle's brake system and then make an educated guess as to the condition of each of the brake components, the current state of the art often gives an inacurrate result.

Normal testing methods also fail to address a crucial issue in brake performance, i.e. the integrity of the brake hydraulic condition. Brake line fluid absorbs water quite readily and any opening in an otherwise closed brake system provides an area where water may be taken up by the brake fluid. When water is found in the brake fluid it promotes corrosion of the parts of the system which will produce a failure of the system at that corroded part.

Additionally the prior methods of brake testing do not relate the state of the brakes or their performance to optimal vehicle specifications as established by the manufacturer.

Accordingly one object of the invention is to provide a mechanism for collecting data on a vehicle's brake system such as measurements of the actual brake pad placement and thickness so as to determine wear and damage and to compare such information to manufacturer specification. A further object of this invention is to measure the water content of the brake fluid at various points to determine the structural integrity of the brake lines and system. Another object of the invention is to provide a method of analysis whereby all salient information is collected and stored so that an accurate diagnosis as to the condition of a vehicle's brake system may be made. Such a method allows the mechanic to keep all test results organized while also accomplishing the objective of reminding the mechanic of all necessary tests that must be performed before an accurate diagnosis can be achieved.

By using the proper flow chart and procedures to diagnosis brake systems, the exact condition of the brake drums, brake rotors, brake linings, brake pads and brake hold down parts can accurately be determined. The inventive device has shown the most efficient and time saving way to diagnose brake condition is to follow a proper flow chart and to use a computer that prompts a technician in a logical step by step procedure to properly inspect the brake system components.

Automotive brake systems are comprised of two separate systems, the mechanical system consisting of the drums, brake rotors, brake linings, brake pads, brake hold downparts, and the hydraulic system that contains a master cylinder, wheel cylinders, calipers, brake lines and brake hoses.

The condition of master cylinders, wheel cylinders and calipers cannot accurately be determined even if a technician follows the best flow chart. The only way to be sure of their condition is to disassemble them and inspect the bore of each cylinder or the caliper piston. However, these hydraulic components most often fail because of oxidation or rust. Oxidation or rust occurs in these cylinders because the brake fluid is water absorbing, or hydroscopic. By using an electronic hydrometer as a component of the inventive device and by using the inventive method to measure the amount of water and contaminates in the brake fluid, an assessment of the condition of the master cylinder, wheel cylinders and the integrity of the hydraulic system can be made accurately and quickly.

FIG. 1 is a plan view of the device showing the interrelationship of the various measuring instruments in the device.

FIG. 2 is a schematic block diagram showing the connection of the various components of the brake testing device.

FIG. 3 is a schematic block diagram showing the interconnection of the keypad input device to the brake testing device.

FIG. 4 is a schematic block diagram showing the interconnections of the hydrometer device with the brake testing device.

FIGS. 5 through 12 are flow diagrams of the diagnostic process.

In FIG. 1 the brake testing device is shown composed of a central processing unit CPU 10 which interfaces with a monitor 20, a keyboard for data entry 30, a micrometer 40, a hydrometer 50 and a torque wrench 60. The central processing unit 10 may be any of a variety of commercially available computers which may be programmed with a variety of commercially available operating systems that are able to receive the inputs from the keyboard 30, the electronic caliper 40, the electronic hydrometer 50, or the electronic torque wrench 60 and display the results of such inputs as well as outputs from the central processing unit 10 on a monitor 20.

In the preferred embodiment, a IBM 286 or IBM clone operating at 12 megahertz with two megabite random access memory on a hard disc drive which has been augmented with a VGA card, a 40 megabite seagate harddrive and a 31/2"1.4 megabite floppy disc has been selected as the central processing unit. Such hardware, in the preferred embodiment, is booted up with a DOS operating system from Micro-Soft and augmented with drivers that allow the central processing unit 10 to interact with the various instruments which are component parts of the device; specifically the caliper 40, the hydrometer 50 and the torque wrench 60. Such drivers are commercially available from companies such as Borland International, Inc. of 1800 Green Hill Road, Scotts Valley, Calif. 95067. Such software is augmented by the specific program which has been appended to this patent application as Appendix A comprising six sheets of computer program listings and illustrating the preferred embodiment of the computer software code contemplated by the invention disclosed herein. In the preferred embodiment, a library of manufacturer's brake specifications is loaded into the CPU memory.

FIG. 2 shows in schematic form the interrelationships between the central processing unit 10, the VGA or MGA monitor 20, the keyboard input device 30, the micrometer or caliper 40, the hydrometer 50, the torque wrench 60, dial indicator 80, and the parallel printer 70.

FIG. 3 is a schematic block diagram of the interconnection between the inputs from the hydrometer 50 and micrometer 40 as they are wired through the multiplexer 12 at port 13 of multiplexer as well as game port 14 of the central processing unit 10 as shown in FIG. 2.

FIG. 4 is a schematic block diagram showing the relationship within the hydrometer 50 as well as the wiring for the results obtained from a reading as shown in indicator lights 53 through 56.

A more complete understanding of the inventive method and the use of the device may be had by reference to the flow diagrams in FIGS. 5 through 12. The analysis of a brake system is begun at FIG. 5 by entering into the CPU 10 from the keyboard 30 the identifying information as to the customer and any performance observations observed during a test drive of the vehicle in question. The program automatically calls up the manufactures specifications on the brake system for that vehicle's particular model from a data base stored in memory of the CPU 10. The technician is then prompted by the computer to perform a brake pedal test, the results of which are entered via the keyboard 30 into the program being run on CPU 10. The technician is then prompted to perform a master cylinder test by use of the hydrometer 50 and the results of the fluid analysis in that master cylinder, i.e., 6000 medium, fair or bad are entered into the program being run. As shown in FIG. 6, the technician is then prompted to perform a wheel test wherein the wheel bearings are checked for movement and the results entered into the program via the keyboard 30. The brake hoses are then visually inspected for cracking or frayed areas and the results are entered into the program via keypad 41 as shown in FIG. 2. As shown in FIG. 7, the rotor drum is measured by use of the micrometer or caliper 40 shown in FIG. 1. The micrometer 40 is used by either increasing the opening of the blades of the micrometer, or decreasing the span and the results are entered into the program automatically by pressing the enter button 43 on keypad 41. A comparison is made by the program with vehicle specifications from the manufacture's information stored in the data base and the program makes the determination as to whether the rotor drum for that wheel passes. Similar measurements are also done for the inboard brake pad and the outboard brake pad and the results compared to manufacture's specifications.

As shown in FIG. 8, the technician is then prompted to visually check the wheel cylinder bleed bleed screw for rust and the technician enters the results into the program. The technician is then prompted to check the wheel cylinder fluid by use of the hydrometer 50 shown in FIG. 1 and measure the water content of the brake fluid by setting switch 45 of the keypad 41 to show a hydrometer reading is being taken as shown in FIG. 2. The probe 51 of hydrometer 50 is then inserted into the fluid and the results of the test are shown on indication lights 53 through 56 which registers respectively good fluid 53, medium fluid 54, fair fluid 55, and bad fluid 56, which results are entered into the program by pressing key 43 of keypad 41.

As shown in FIG. 9, the cylinder piston for that wheel is then checked visually for movement and the results entered into the program, the dust bout inspected defects and the results entered into the program. The remaining brake holddown hardware is inspected visually for defects with the results entered into the program. These tests are repeated for each wheel.

As shown in FIGS. 8, 10, 11 and 12, the results of the tests are compared to vehicle specifications from the manufacturer and a printout via printer 70 is made identifying the defects in the brake system. The technician is then prompted to make the repairs called for by the program. After such repairs are made a final check of the system is made by prompting the technician to recheck the areas repaired and a printout is made of the problems encountered and the repairs made via printer 70 FIG. 2. The wheels are re-assembled and the trueness of the rotor is checked by use of the dial indicator 80. The tires and rims are bolted back onto the wheel using the electronic torque wrench 60 which tightens the lug bolt nuts to the appropriate tightness.

The preferred embodiments of the present invention have been described herein and shown in the accompanying drawing to illustrate the underlying principles of the invention, but it is to be understood that a number of modifications or alternate embodiments may be made utilizing either the components described herein, the alternate components described herein, or their equivalents in a variety of combinations, all without departing from the spirit and scope of the invention.