Antiskid brake control system having malfunction protection

• US 3,920,280 A
• Filed: 05/23/1974
• Issued: 11/18/1975
• Est. Priority Date: 08/10/1973
• Status: Expired due to Term

• Current Assignee: Alfred Klatt, Dieter Luhdorff, Erich Reinecke, Lutz Weise
• Original Assignee: Alfred Klatt, Dieter Luhdorff, Erich Reinecke, Lutz Weise
• Inventors: Luhdorff, Dieter, Weise, Lutz, Reinecke, Erich, Klatt, Alfred
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/472,609
• Time in Patent Office: 544 Days
• Field of Search: 188/181 235/153AE 303/20,21 307/1R,204,219 317/5 324/161-162 340/52B,53,62,146.1BE,262,263
• US Class Current: 303/122.06
• CPC Class Codes: B60T 2270/416 Wheel speed sensor failure
• CPC Class Codes: B60T 8/885 using electrical circuitry

Abstract

A vehicle antiskid brake control system in which a skid control signal for modulating brake pressure at any one of the wheels is obtained when a disparity results from the comparison of a wheel velocity signal with a reference velocity signal formed by one or more of the wheel velocity signals so as to approximate the vehicle speed. The system includes an additional wheel velocity signal generator network in parallel with the conventional signal generator network at one or more wheels together with low and high signal selectors arranged so that a false wheel velocity signal arising from one of the signal generator networks due to a malfunction is rejected, thereby assuring that only the accurate wheel velocity signal from the other signal generator network is capable of influencing formation of the reference signal.

Claims

1. A vehicle antiskid brake control system comprising:

a. first means for providing wheel velocity signals according to the speeds of rotation of the individual wheels of the vehicle;

b. means for forming a reference velocity signal from a wheel velocity signal of at least one wheel of the vehicle as an approximation of the vehicle speed;

c. means for comparing said wheel velocity signals of the individual wheels with said reference velocity signal to obtain a wheel Skid control signal when differences therebetween occur so as to effect modulation of brake pressure at whichever wheel is providing said wheel velocity signal different than said reference velocity signal;

wherein the improvement comprises;

d. second means in parallel with said first means for providing additional wheel velocity signals according to the speeds of rotation of the individual wheels of the vehicle in addition to said first mentioned wheel velocity signals thereof and e. said means for forming a reference velocity signal including third means for selecting the lower one of said additional and said first mentioned velocity signals of said at least two wheels for use in forming said reference velocity signal.

2. An antiskid brake control system as recited in claim 1, further comprising:

a. fourth means for selecting the higher of said first mentioned wheel velocity signals corresponding to the speed of rotation of at least two individual wheels; and

b. fifth means for selecting the higher of said additional wheel velocity signals of said at least two wheels, whereby said lower one of said first mentioned wheel velocity signals and said additional wheel velocity signals selected by said third means for use in forming said reference velocity signal is the higher of said first mentioned wheel velocity signals and said additional wheel velocity signals of said at least two wheels.

3. An antiskid brake control system as recited in claim 2, further comprising:

a. sixth means for selecting a first output signal according to the higher of said wheel velocity signals selected by said fourth and said fifth means;

b. seventh means for selecting a second output signal according to the lower of said wheel velocity signals of at least said two wheels;

c. means for comparing said first and second output signals to provide an error signal when said first and second output signals differ; and

d. means responsive to said error signal for interrupting operation of the antiskid brake control system except when a brake application is already in effect at the time said error signal arises.

4. An antiskid brake control system as recited in claim 3, wherein said means for interrupting operating of the antiskid brake control system comprises an AND gate having one input subject to said error signal, a negated input subject to a brake pressure signal and an output providing an antiskid control cut-out signal only when said AND gate is enabled by the absence of said brake pressure signal at the time said error signal arises.

5. An antiskid brake control system as recited in claim 4, further comprising means for delaying reception of said error signal at said one input of said AND gate.

6. An antiskid brake control system as recited in claim 4, further comprising means operatively responsive to the presence of said error signal for indicating a wheel skid condition.

7. An antiskid brake control system as recited in claim 4, further comprising means for sustaining said brake pressure signal a predetermined duration following release of a brake application.

8. An antiskid brake control system, as recited in claim 1, further comprising differentiator means subject to said additional wheel velocity signal for providing a deceleration signal to effect modulation of brake pressure at an individual wheel whose rate of deceleration exceeds a certain chosen value.

9. An antiskid brake control system as recited in claim 1, further comprising memory means for modifying said wheel velocity signals such that said reference velocity signal approximates the vehicle speed during such time as said wheel velocity signals reflect a wheel whose rate of deceleration exceeds a certain chosen value.