BRAKE FORCE CONTROL SYSTEM FOR VEHICLES

• US 3,797,893 A
• Filed: 07/06/1972
• Issued: 03/19/1974
• Est. Priority Date: 07/06/1971
• Status: Expired due to Term

• Current Assignee: Hellmut Krohn, Manfred H. Burckhardt
• Original Assignee: Hellmut Krohn, Manfred H. Burckhardt
• Inventors: Burckhardt, Manfred H., Krohn, Hellmut
• Primary Examiner(s): Halvosa, George E. A.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/269,433
• Time in Patent Office: 621 Days
• Field of Search: 188/181 303/20,21 324/161-162 340/52B,262-263 180/82R,103,104
• US Class Current: 303/159
• CPC Class Codes: B60T 8/17613 based on analogue circuits or digital circuits comprised of discrete electronic elements
• CPC Class Codes: B60T 8/58 responsive to speed and another condition or to plural speed conditions

Abstract

A brake force control system for vehicles, especially for motor vehicles, in which a sensor is coordinated to each wheel for determining its rotational condition, whose signals actuate inlet and outlet valves when exceeding or dropping below certain threshold values so that the brake pressure either increases, remains constant, or decreases, whereby, particularly in vehicles with a high center of gravity and especially with a short wheel base, an additional logic circuit connection is provided which decreases the pressure at the front wheel brakes if a signal symbolizing the road traction of the rear wheels does not arrive within a certain delay.

Claims

1. A brake force control system for vehicles with front and rear wheel brakes controlled by valve means, especially for motor vehicles, which includes means coordinated to each wheel for detecting the rotational condition of the wheel and operable to produce signals representative of such conditions, inlet and outlet valve means, and connecting means including logic circuit means for actuating said valve means in response to the signals of the detecting meansexceeding or dropping below certain threshold values so means exceeding the brake pressure either increases, remains constant or decreases, characterIzed in that the connecting means includes additional logic circuit means operatively connected between the detecting means and the valve means which include means for decreasing the pressure at the front wheel brakes if a signal symbolizing the road adherence of the rear wheels does not arrive within a predetermined delay.

2. A brake force control system according to claim 1, characterized in that control system is used in vehicles with high center of gravity and short wheel base. beginning after

3. A brake force control system according to claim 1, wherein the control system provides a pure acceleration control or combined acceleration-slippage control, characterized in that the additional logic circuit connection means includes means for decreasing the pressure at the front wheel brakes if not reacceleration signal occurs at the rear wheels after a delay of about 200-300 ms. -beginningafter the expiration of the filtering time following a pressure decrease signal at the rear wheels.

4. A brake force control system according to claim 1, wherein the control system provides a pure slippage control or a pure slippage guidance of the rear wheels, characterized in that the additional logic circuit means includes means for decreasing the pressure at the front wheel brakes if after a delay of about 100 to 200 ms. -beginning with the pressure decrease signal when exceeding the upper slippage threshold of the rear wheels-a dropping below a slippage threshold is not signalled at the rear wheels.

5. A brake force control system according to claim 1, characterized in that the logic circuit means include means for blocking the pressure increase signals for the front wheels in the presence of a pressure decrease signal at the rear wheels and for permitting the passage of only pressure decrease signals for the front wheels.

6. A brake force control system, according to claim 5, characterized in that the additional logic circuit means includes means responsive only to the signals of one rear wheel.

7. A brake force control system according to claim 5, characterized in that the additional logic circuit means responsive only to the signals of both rear wheels.

8. A brake force control system according to claim 5, characterized by means for realizing the pressure decrease at the front wheel brakes intermittently.

9. A brake force control system, according to claim 1, characterized in that the additional logic circuit means includes means responsive only to the signals of one rear wheel.

10. A brake force control system according to claim 1, characterized in that the additional logic circuit includes means responsive only to the signals of both rear wheels.

11. A brake force control system according to claim 1, characterized by means for realizing the pressure decrease at the front wheel brakes intermittently.

12. A brake force control system for the brakes of vehicles equipped with control valve means, in which a sensing means coordinated to each wheel for determining its rotational condition, influences the brakes when a predetermined threshold value is exceeded or dropped below, each sensing means includes means responsive to the speed of the wheel for providing measuring magnitudes in the form of first, second and third signals representing wheel slippage, acceleration and deceleration, respectively, threshold circuit means for each of these signals for providing an output signal indicative of whether the threshold value has been exceeded or not, means for combining the output signals of said threshold circuit means to provide an output signal which serves as a control signal for the value means of the brakes, and additional means operatively connected between said sensing means and the valve means for producing control signals overriding said first-mentioned control signal to decrease the pressure at the front wheel brakes if a signal indicative of road traction at the rear wheels does not arrive within a predetermined delay.

13. A brake force control system according to claim 12, characterized in that the measuring magnitude which is proportional to the rotational speed and is derived from the corresponding sensing means, serves, on the one hand, for the formation of the measuring magnitude representing the slippage by a comparison with a comparison standard representing the speed of the fastest wheel and, on the other, for the formation of the measuring magnitude representing the acceleration by differentiation.

14. A brake force control system according to claim 13, characterized by comparison means operatively connected to said sensing means for producing the measuring magntidue representing the slippage and differentiating means operatively connected with the corresponding sensing means for forming the measuring magnitude representing the acceleration.

15. A brake force control system according to claim 13, characterized in that a frequency generator means is drivingly connected with each wheel as sensing means.

16. A brake force control system according to claim 15, characterized in that the frequency generator means is arranged at a respective wheel.

17. A brake force control system according to claim 15, characterized in that a frequency voltage converter means is operatively connected with each frequency generator means, the output from said frequency voltage converter means being connected together by way of diodes to a point for forming the maximum voltage representing the speed of the fastest wheel, while the outputs of said frequency voltage converter means are also operatively connected with differentiator means in by-passing relationship to the maximum voltage point.

18. A brake force control system according to claim 17, characterized in that the maximum voltage prevailing at the maximum voltage point is subdivided at the ratio of the desired response condition by resistance means and a partial voltage is fed to a differential amplifier means constructed as threshold circuit means.

19. A brake force control system according to claim 12, characterized in that a frequency voltage converter means is operatively connected with each frequency generator means drivingly connected with each wheel as sensing means, the outputs from said frequency voltage converter means being connected together by way of diodes to a point for forming the maximum voltage representing the speed of the fastest wheel, while the outputs of said frequency voltage converter means are also operatively connected with differentiator means in by-passing relationship to the maximum voltage point.

20. A brake force control system according to claim 19, characterized in that the maximum voltage prevailing at the maximum voltage point is subdivided at the ratio of the desired response condition by resistance means and a partial voltage is fed to a differential amplifier means constructed as threshold circuit means.

21. A brake force control system according to claim 12, characterized by a safety installation for continuously monitoring and supervising the control system which prevents a transmission of signals to an adjusting valve means in case of erroneous signals.

22. A brake force control system according to claim 21, characterized in that the adjusting valve means for valves of the brakes are so actuated in case of erroneous signals that the brakes operate in the normal manner.

23. A brake force control system according to claim 21, characterized in that the safety installation includes an electric logic circuit means operatively connected between an output transistor and its corresponding adjusting means which de-energizes the adjusting valve means in case of response of its circuit.

24. A brake force control system according to claim 23, characterized in that the test program means are provided for applying signals to the control system with non-actuated brakes for producing output control signals by the simulated rotational speed changes thereof which are continuously monitored by the safetY installation.

25. A brake force control system for the brakes of vehicles equipped with control valve means, in which a sensing means coordinated to each wheel for determining its rotational condition influences the brakes when a predetermined threshold value is exceeded or dropped below, each sensing means includes means responsive to the speed of the wheel for providing measuring magnitudes in the form of first, second and third signals representing wheel slippage, acceleration and deceleration, respectively, threshold circuit means for each of these signals for providing an output signal indicative of whether the threshold value has been exceeded or dropped below, each sensing means includes means responsive to the speed of the wheel for providing measuring magnitudes in the form of first, second and third signals representing wheel slippage, acceleration and deceleration, respectively, threshold circuit means for each of these signals for providing an output signal indicative of whether the threshold value has been exceeded or not, means for combining the output signals of said threshold circuit means to provide an output signal which serves as a control signal for the valve means of the brakes, and additional means operatively connected between said sensing means and the valve means for producing control signals overriding said first-mentioned control signal to decrease the pressure at the front wheel brakes if a signal indicative of road traction at the rear wheels does not arrive within a predetermined delay, in that the measuring magnitude which is proportional to the rotational speed and is derived serves, on the one hand, for the formation of the measuring magnitude representing the slippage by a comparison with a comparison standard representing the speed of the fastest wheel and, on the other, for the formation of the measuring magnitude representing the acceleration by differentiation, in that a frequency generator means is drivingly connected with each wheel as sensing means, in that a frequency voltage converter means is operatively connected with each frequency generator means, the outputs from said frequency voltage converter means being connected together by way of diodes to a point for forming the maximum voltage representing the speed of the fastest wheel, while the outputs of said frequency voltage converter means are also operatively connected with differentiator means in by-passing relationship to the maximum voltage point, in that the maximum voltage prevailing at the maximum voltage point is subdivided at the ratio of the desired response condition by resistance means and a partial voltage is fed to a differential amplifier means constructed as threshold circuit means, and in that each differentiator means is connected with its output to two parallel frequency weighting means which, in their turn, are each operatively connected with a respective differential amplifier means constructed as threshold circuit means.

26. A brake force control system according to claim 25, characterized in that the frequency weighting means for deceleration and acceleration are different.

27. A brake force control system according to claim 26, characterized in that one threshold circuit means each for slippage, for acceleration and for deceleration is operatively associated with each adjusting valve means present in a respective brake circuit, the output signals of the three threshold circuit means being interconnected by combining means in the form of a logic circuit means according to a predetermined logic arrangement.

28. A brake force control system according to claim 27, characterized in that the threshold circuit means are differential amplifier means for the slippage, for the acceleration and for the deceleration.

29. A brake force control system according to claim 27, characterized in that the logic circuit means includes integrated circuits with a NOR-element having three inputs and a NOR-element having two inputs for each adjusting means.

30. A brake fOrce control system according to claim 29, characterized in that the output of each threshold circuit means is connected with one input of the NOR-element having three inputs whose output is connected with one input of the NOR-element having two inputs while the second input of the NOR-element having two inputs is operatively connected with the differential amplifier means of the threshold circuit means representing the acceleration.

31. A brake force control system according to claim 30, characterized by a safety installation for continuously monitoring and supervising the control system which prevents a transmission of signals to the adjusting valve means in case of erroneous signals.

32. A brake force control system according to claim 31, characterized in that the adjusting valve means for the valves of the brakes are so actuated in case of erroneous signals that the brakes operate in the normal manner.

33. A brake force control system according to claim 32, characterized in that the safety installation includes an electric logic circuit means operatively connected between an output transistor and its corresponding adjusting valve means which de-energizes the adjusting valve means in case of response of its circuit.

34. A brake force control system according to claim 33, characterized in that the adjusting valve means are solenoid valves which are de-energized.

35. A brake force control system according to claim 33, characterized in that test program means are provided for applying signals to the control system with non-actuated brakes for producing output control signals by the simulated rotational speed changes thereof which are continuously monitored by the safety installation.

36. A brake force control system for the brakes of vehicles equipped with control valve means, in which a sensing means coordinated to each sheel for determining its rotational condition influences the brakes when a predetermined threshold value is exceeded or dropped below, each sensing means includes means responsive to the speed of the wheel for providing measuring magnitudes in the form of first, second and third signals representing wheel slippage, acceleration and deceleration, respectively, threshold circuit means for each of these signals for providing an output signal indicative of whether the threshold value has been exceeded or not, means for combining the output signals of said threshold circuit means to provide an output signal which serves as a control signal for the valve means of the brakes, and additional means operatively connected between said sensing means and the valve means for producing control signals overriding said first-mentioned control signal to decrease the pressure at the front wheel brakes if a signal indicative of road traction at the rear wheels does not arrive within a predetermined delay, in that a frequency voltage converter means is operatively connected with each frequency generator means drivingly connected with each wheel as sensing means, the outputs from said frequency voltage converter means being connected together by way of diodes to a point for forming the maximum voltage representing the speed of the fastest wheel, while the outputs of said frequency voltage converter means are also operatively connected with differentiator means in by-passing relationship to the maximum voltage point, in that the maximum voltage prevailing at the maximum voltage point is subdivided at the ratio of the desired response condition by resistance means and a partial voltage is fed to a differential amplifier means constructed as threshold circuit means, and in that each differtiator means is connected with its output to two parallel frequency weighting means which, in their turn, are each operatively connected with a respective differential amplifier means constructed as threshold circuit means.

37. A brake force control system according to claim 36, characterized in that the frequency weighting means for deceleration and acceleration are different.

38. A brake force control system for vechicles with front and rear wheels according to claim 36, characterized in that said additional means includes separator means operable to separate out signals according to the polarity thereof and timer means operable to produce an output signal in the absence of an input signal within a predetermined delay from the time each timer means starts to run, said separator means and timer means having input and output means, the input means of the separator means being operatively connected to the outputs of the differential amplifier means associated with the rear wheels, the output means of the separator means being operatively connected to the input means of the timer means, and means operatively connecting the outupt means of the timer means to the control valve means of the front wheels to decrease the braking pressure at the front wheels in the absence of a signal, symbolizing road adherence of the rear wheels, at the input means of the timer means within said predetermined delay.

39. A brake force control system for the brakes of vehicles equipped with control valve means, in which a sensing means coordinated to each wheel for determining its rotational condition influences the brakes when a predetermined threshold value is exceeded or dropped below each sensing means includes means responsive to the speed of the wheel for providing measuring magnitudes in the form of first, second and third signals representing wheel slippage, acceleration and deceleration, respectively, threshold circuit means for each of these signals for providing an output signal indicative of whether the threshold value has been exceeded or not, means for combining the output signals of said threshold circuit means to provide an output signal which serves as a control signal for the valve means of the brakes, and additional means operatively connected between said sensing means and the valve means for producing control signals overriding said first-mentioned control signal to decrease the pressure at the front wheel brakes if a signal indicative of road traction at the rear wheels does not arrive within a predetermined delay, and in that one threshold circuit means each for slippage, for acceleration and for deceleration is operatively associated with each adjusting valve means present in a respective brake circuit, the output signals of the three threshold circuit means being interconnected by combining means in the form of a logic circuit means according to a predetermined logic arrangement.

40. A brake force control system according to claim 39, characterized in that the threshold circuit means are differential amplifier means for the slippage, for the acceleration and for the deceleration.

41. A brake force control system according to claim 39, characterized in that the logic circuit means includes integrated circuits with a NOR-element having three inputs and a NOR-element having two inputs for each adjusting means.

42. A brake force control system according to claim 41, characterized in that the output of each threshold circuit means in connected with one input of the NOR-element having three inputs whose output is connected with one input of the NOR-element having two inputs while the second input of the NOR-element having two inputs is operatively connected with the differential amplifier means of the threshold circuit means representing the acceleration.

43. A brake force control system for vehicles with front and rear wheel brakes controlled by valve means, especially for motor vehicles, the control system including sensing means coordinated to at least one wheel of each of a front and rear axle for detecting the rotational condition of the wheel and for producing signals representative of the rotational condition, inlet and outlet valve means, and connecting means including logic circuit means for actuating the valve means in response to the signals of the sensing means exceeding or dropping below predetermined threshold values so that the braKe pressure either increases, remains constant or decreases, characterized in that the connecting means includes additonal logic circuit means for preventing excessive forward pitching of the vehicle, the additional logic circuit means being operatively connected between the sensing means and the valve means and including decreasing pressure means responsive to the absence of a signal indicative of the road adherence of the rear wheels within a predetermined period of time for controlling the valve means for the front wheel brakes to decrease the pressure thereat so as to prevent excessive forward pitching of the vehicle.

44. A brake force control system according to claim 43, characterized in that the pressure decreasing means only decreases the pressure at the front wheel brakes.