Brake anti-lock test system

• US 3,866,980 A
• Filed: 06/28/1973
• Issued: 02/18/1975
• Est. Priority Date: 06/29/1972
• Status: Expired due to Term

• Current Assignee: Ardelio Gualco, Friedrich Rabus, Harald Kizler, Hermann Eisele, Johannes Locher, Peter Jurgen Schmidt, Wolfgang Misch
• Original Assignee: Ardelio Gualco, Friedrich Rabus, Harald Kizler, Hermann Eisele, Johannes Locher, Peter Jurgen Schmidt, Wolfgang Misch
• Inventors: Eisele, Hermann, Kizler, Harald, Schmidt, Peter Jurgen, Locher, Johannes, Misch, Wolfgang, Gualco, Ardelio, Rabus, Friedrich
• Primary Examiner(s): Halvosa, George E. A.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/374,306
• Time in Patent Office: 600 Days
• Field of Search: 303/21AF 324/51,73R 340/52R,52B,410
• US Class Current: 303/122.1
• CPC Class Codes: B60T 2270/406 Test-mode; Self-diagnosis
• CPC Class Codes: B60T 8/58 responsive to speed and another condition or to plural speed conditions
• CPC Class Codes: B60T 8/885 using electrical circuitry
• CPC Class Codes: B60T 8/90 using a simulated speed signal to test speed responsive control means
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder

Abstract

To test operational reliability and proper functioning of a wheel brake antilock system having a fluid operated brake, a pressure relief valve in the pressure feed line to the brake and various switches controlling operation of the relief valve, controlled by wheel deceleration (acceleration) sensing apparatus, a pressure switch is connected to be responsive to pressure in one brake cylinder, and electrical apparatus are provided to simulate a wheel deceleration signal which is connected to control operation of the switch which operates the relief valve, a test indicator is provided and further electrical apparatus which senses change in response of the pressure switch upon energization of the system, so that malfunction, for example non-response of the system, or excessive bleeding of brake pressure fluid can be indicated.

Claims

1. Test system to test operational reliability of a vehicle wheel brake anti-lock system having a pressure fluid operated brake, a pressure relief valve (14) in the pressure fluid line to the brake, controlled switching means (38) controlling operation of said relief valve (14), and a wheel acceleration sensing means (29) having means (32, 33) generating a deceleration signal (b1) connected to and controlling operation of the controlled switch means (38) when a predetermined level of wheel deceleration is sensed, said test and monitor system comprising a pressure switch (25) connected to be responsive to fluid pressure in the respective wheel brake cylinder (16) and providing a pressure signal (p1);

electrical means (54) generating a simulated wheel deceleration signal (w) connected to the deceleration signal generating means (32,

     33);

a test indicator (60);

a logic circuit (44) having said deceleration signal (b1) and said pressure signal (p1) applied thereto and logically combining said signals to provide an output signal indicative of presence of the pressure signal (p1) and the wheel deceleration signal (b1); and

controlled switch means (45) connected to said indicator, and being controlled to set to '"'"''"'"''"'"''"'"'test'"'"''"'"''"'"''"'"' state upon energization of the controlled switching means, said controlled switch means being further connected to and controlled by the output of said logic circuit (44) to reset in response to an output from said logic circuit (44).

2. System according to claim 1 wherein the deceleration simulation means comprises a monostable flip-flop (54).

3. System according to claim 1 wherein the controlled switch means sensing output from said logic circuit (44) comprises a first bistaBle flip-flop (45) having a set input (S) and a reset input (R), an energization switch (61) for the system, the set input (S) being controlled by the energization switch and the reset input (R) by said logic circuit (44).

4. System according to claim 1 for use with a wheel anti-lock system wherein the wheel acceleration-deceleration sensing means comprises a pulse tachometer generator (30), a frequency voltage converter (31) connected to the tachometer generator, and a differentiator (32) connected to receive the output from the converter to provide a wheel rate of change signal, and a first threshold switch (33) forming said deceleration signal generating means and providing said deceleration signal when the wheel speed rate of change exceeds the predetermined level;

the output (w) of the wheel deceleration simulating means (54) being connected to the input of the differentiator (32); and

the logic circuit (44) comprises a logic gate (44), having the outputs of the first threshold switch (33) and of the pressure switch (25) applied thereto, the output of the logic gate (44) being connected to said controlled switch means (45).

5. System according to claim 4 wherein said controlled switch means comprises a first bistable flip-flop (45), the output of said logic gate (44) being connected to the reset input (R) of the first bistable flip-flop (45).

6. System according to claim 4 wherein the wheel anti-lock system further comprises a speed comparison loop including a comparator comparing circumferential wheel speed and vehicle speed, the comparator (35) having one input connected to the output of the frequency - voltage converter, and wherein a second threshold switch (36) is provided controlled by the output from said comparator (35) and changing state when sensed wheel speed and vehicle speed exceed a predetermined level;

and wherein the output of the second threshold switch (36) is connected as a further input to the logic gate (44).

7. System according to claim 6 to test the operating reliability of a plurality of wheel brake anti-lock systems, associated with different wheels of the vehicle, wherein a plurality of logic gates (41, 42, 43) are provided, having their outputs connected to said first logic gate (44);

said plurality comprising at least second, third and fourth logic gates, the second logic gate (41) having connected thereto as input the outputs of all the pressure switches (25) associated with the respective vehicle wheels;

the inputs of the third logic gate (42) being connected to the outputs of all the second threshold switches (36) associated with the respective anti-lock systems; and

the inputs of the fourth logic gate (43) being connected to the outputs of all the first threshold switches (33) of all the anti-lock systems.

8. System according to claim 7 wherein the controlled switch means sensing change of response of the pressure switches comprises a first bistable flip-flop (45) having a set input (S) and a reset input (R);

a second bistable flip-flop (48), the output of the second bistable flip-flop being connected to the first logic gate (44) the set inputs of said flip-flops (45,

     48) being enabled by the main switch of the vehicle; and

a system logic gate (47) is provided, all pressure switches (25), all first threshold switches (33) and all second threshold switches (36) being connected to the inputs of the system logic gate (47), the output of the system logic gate controlling the reset terminal of the second bistable flip-flop (48), the reset terminal of said first bistable flip-flop (45) being controlled by said pressure switches (25).

9. System according to claim 8 wherein said system logic gate is a conjunctive gate (NOR - 47).

10. System according to claim 8 wherein said first logic gate is a conjunctive gate (NOR - 44).

11. System according to claim 7 wherein the electrical means simulating a wheel deceleration signal comprises a monostable flip-flop (54);

a third bistable flip-flop (53) is provided, the output of the second logic gate (41) being connected to the reset input of the third bistable flip-flop (53), the set input of the third bistable flip-flop being connected to the main vehicle switch (61) and said monostable flip-flop (54) being controlled by the output from the third bistable flip-flop (53).

12. System according to claim 11 wherein the vehicle has a parking brake switch (49), a fifth logic gate (52) is provided connected to the reset input (R) of the third bistable flip-flop (53);

said fifth logic gate having connected to its inputs;

the parking brake switch (49) and the output of said second logic gate (41).

13. System according to claim 12 wherein said fifth logic gate is a conjunctive gate (NOR - 52).

14. System according to claim 11 wherein the vehicle has a parking brake switch (49);

the system comprises a fifth logic gate (52), the output of the fifth logic gate (52) being connected to the set input (S) of the monostable flip-flop (54) forming said wheel deceleration simulating means, the inputs to fifth logic gates comprising;

the output of the parking brake switch (49) and the output of a third bistable flip-flop (53), the setting of which is controlled by closing of the main vehicle switch (61) and the resetting by sensing of change in pressure of the pressure switches of the vehicle brake anti-lock systems (FIG.

     6).

15. System according to claim 14 wherein the fifth logic gate (52) is a conjunctive gate.

16. System according to claim 7 further comprising a sixth logic gate (58), the output of which is connected to the test indicator (60), the outputs of the third logic gate (42) and of the first bistable flip-flop (45) being connected to inputs of said sixth logic gate (58) to provide an indication of malfunction during operation of the vehicle by energization of the indicator upon simultaneous occurrence of sensing of change of response of the pressure switch and difference between wheel speed and vehicle speed in excess of a predetermined value.

17. System according to claim 16 wherein said sixth logic gate comprises a conjunctive gate (NOR-58).

18. System according to claim 16 further comprising additional inputs (52'"'"''"'"') to said fifth logic gate (52), said additional inputs being connected to stages of the anti-lock system to be monitored.

19. System according to claim 18 further comprising a seventh logic gate (57) having its output connected to an additional input of the sixth logic gate (58);

one input of said seventh logic gate being connected to the brake light switch (28) of the vehicle, and another input of the seventh logic gate being connected to the output of the third logic gate (42), said seventh logic gate being conjunctive.

20. System according to claim 1 wherein a single test system is provided to test the operability of a plurality of wheel anti-lock systems, each one associated with a different wheel of the vehicle;

wherein said test and monitoring system comprises a plurality of logic gates (41, 42,

     43), one of said logic gates (41) being connected to all the pressure switches (25) of the respective anti-lock systems, and sensing brake fluid pressure (p1) in the respective wheel brake cylinders; and

wherein the wheel anti-lock systems each comprise at least one threshold switch (35,

     36) responding when the difference in respective wheel speed and between another measured speed exceeds a predetermined limit, said test and monitoring system further comprising at least one further logic gate (42) and having connected thereto as input (v1) the outputs of all said threshold switches (36) comparing wheel speed with another speed.

21. System according to claim 20 wherein two further logic gates (42, 43) are provided, said one logic gate (42) having connected as an input signal representative of difference between wheel circumferential speed and vehicle speed in excess of a predetermined level;

and the otHer logic gate (43) having connected thereto as inputs said deceleration signals (b1) representative of instantaneous rate of change of wheel speed in excess of the predetermined level.

22. System according to claim 1 wherein the system comprises a plurality of bistable flip-flops (45, 48, 53);

the vehicle has a main switch (61) and a source of power supply (62); and

a capacitor (46) is provided, connected to the set inputs (S) of the bistable flip-flops (45, 48,

     53) and to the switch, to transfer a pulse to the set inputs upon closing of the switch.

23. System according to claim 1 wherein the vehicle has a main switch (61) connectible to a source of vehicle power supply (62);

said system comprises at least one bistable flip-flop (45, 48,

     53); and

a trigger monostable flip-flop (64) is provided, connected to the set inputs (S) of the bistable flip-flops (45, 48,

     53) the trigger flip-flop being triggered by closing of the main vehicle switch (61) and connection to the vehicle power supply.

24. System according to claim 1 wherein said system comprises logic gates including at least one of:

NAND-gates;

NOR-gates;

inverter stages; and

wherein the logic gates comprise DTLZ components to improve noise rejection of the system.

25. System according to claim 1 wherein the test indicator (60) includes a light indicator connected to light during test, and extinguishing upon proper operation of the system and after said wheel deceleration signal simulating means has operated to simulate wheel deceleration, resulting in the wheel anti-lock system passing through all steps of a first cycle of simulated response to simulated wheel deceleration above a predetermined limit.

26. System according to claim 1 further comprising a logic circuit (NOR-57;

NAND-42) interconnecting the pressure switch, the test indicator (60) and the acceleration sensing means (29), said logic circuit being connected to energize the test indicator when;

a. the acceleration sensing means (29) provides an output indicative of excessive wheel deceleration and b. the pressure switch is in a position indicative of non-operation of the brake, to provide an output indicative of trouble in the brake anti-lock system and when the brake has not been operated.

27. Test system to test operational reliability of a vehicle wheel brake anti-lock system having a pressure fluid operated brake and a controller therefor, a pressure relief valve (14) in the pressure fluid line to the brake, controlled switch means (38) controlling operation of said relief valve (14), a wheel deceleration/acceleration sensing means (29), an anti-lock circuit controlled by the deceleration/acceleration sensing means connected to and controlling operation of the controlled switch means (38) when a predetermined level of wheel rate of change of speed is sensed, a vehicle main switch (61) to connect the system to a source of power (62, 26), and a brake monitor switch (28;

c) operated upon operation of the vehicle brake controller, said test and monitor system comprising means (25) connected to be responsive to fluid pressure in the respective brake cylinder (16);

electric means simulating, for a limited time, a wheel rate of change of speed signal and energized upon energization of the main switch (61), the wheel rate of change of speed signal being thereupon applied to said anti-lock circuit;

a logic circuit energized upon energization of the main switch (61), the anti-lock circuit being connected to said logic circuit, said logic circuit evaluating the response of said anti-lock circuit upon having said simulated wheel deceleration signal applied thereto and upon operation of the brake controller, said logic circuit including electrical means (45) connected to said pressure sensing means (25) to sense change of fluid pressure commanded by the controller and modified by said anti-lock system;

a test indicator (60) connected in the logiC circuit and providing an indication during;

a. simultaneous application of brake pressure by the brake controller and b. initial response of the anti-lock system and continued bleeding of pressurized brake fluid, the indicator changing-indication upon cessation of bleeding of pressurized brake fluid when the simulated wheel rate of change of speed signal has terminated, to thereby indicate proper operation of the anti-lock system, but remaining in indicated position upon malfunction due to non-response of the anti-lock system or continued response of the anti-lock system after cessation of said simulated wheel rate of change of speed signal.