Failsafe system for skid control systems and the like

• US 3,891,279 A
• Filed: 10/19/1973
• Issued: 06/24/1975
• Est. Priority Date: 10/19/1973
• Status: Expired due to Term

• Current Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: John S. Frait
• Inventors: Frait, John S.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/408,104
• Time in Patent Office: 613 Days
• Field of Search: 246/167R 303/7,20,21AF 324/51 340/52B,213,253B,253C,255,256,409,415
• US Class Current: 303/122.05
• CPC Class Codes: B60T 2270/414 Power supply failure
• CPC Class Codes: B60T 8/885 using electrical circuitry
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/28 Testing of electronic circuits, e.g. by signal tracer EMC, EMP or similar testing of electronic circuits G01R31/002; testing for short-circuits, discontinuities, leakage or incorrect line connection G01R31/50; checking computers or computer components G06F11/00; checking static stores for correct operation G11C29/00 ; testing receivers or transmitters of transmission systems H04B17/00

Abstract

A failsafe system for a skid control system for a multi-axle wheeled vehicle. The skid control system has a plurality of skid control modules, each of which is operatively associated with one of the axles of the vehicle and the skid control modules are operatively coupled by wiring on the vehicle. Each skid control module comprises a skid control circuit for skid controlling the wheels of the associated axle, which circuit is supplied from an electrical power source such as the vehicle battery, either regulated or unregulated. A failsafe circuit is provided in each skid control module and the failsafe circuits of the several modules are connected in cascade fashion to form a chain. An input signal is supplied to the input of the first of the cascaded failsafe circuits and can propagate through the chain of failsafe circuits to the output of the last failsafe circuit only if wiring connecting the modules is proper, the failsafe circuits themselves are operating properly, and electrical power is supplied to each module. A warning occurs when the signal fails to propagate through all the failsafe circuits, and this indicates loss of power or a fault in the modules or the wiring connecting the modules.

Claims

1. In a multi-axle wheeled vehicle having a plurality of skid control modules with each skid control module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels of the associated axle and first and second supply terminals to which first and second reference potentials are intended to be respectively supplied, and including supply means for supplying said first and second reference potentials, the invention wherein each said skid control module further includes a failsafe circuit means having an input terminal to which an input signal is intended to be supplied and an output terminal which is intended to supply an output signal, means for supplying an input signal to the input terminal of one of said failsafe circuit means, means for operatively coupling the output terminal of each preceding failsafe circuit means to the input terminal of the succeeding failsafe circuit means whereby an output signal from the failsafe circuit means of a preceding skid control module is supplied as the input signal to the failsafe circuit means of a succeeding skid control module, each said failsafe circuit means comprising means responsive to the presence of an input signal at its input terminal and tHe presence of the respective reference potentials at the respective supply terminals of its module for providing an output signal at its output terminal only when all of said input signal and said respective reference potentials are present, and warning means operatively coupled with the output terminal of failsafe circuit means of the last succeeding skid control module for providing a warning when an output signal does not appear at the output terminal of said last-mentioned failsafe circuit means so as to indicate when one of said input signal and said respective reference potentials is not present at any one of said failsafe circuit means.

2. The invention as claimed in claim 1 wherein one of said reference potentials is ground.

3. In a multi-axle wheeled vehicle having a plurality of skid control modules with each skid control module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels of the associated axle and first and second supply terminals to which first and second reference potentials are intended to be respectively supplied, and including supply means for supplying said first and second reference potentials, the invention wherein each said skid control module further includes a failsafe circuit means having an input terminal to which an input signal is intended to be supplied and an output terminal which is intended to supply an output signal, means for supplying an input signal to the input terminal of one of said failsafe circuit means, means for operatively coupling the output terminal of each preceding failsafe circuit means to the input terminal of the succeeding failsafe circuit means whereby an output signal from the failsafe circuit means of a preceding skid control module is supplied as the input signal to the failsafe circuit means of a succeeding skid control module, each said failsafe circuit means comprising means responsive to the presence of an input signal at its input terminal and the presence of the respective reference potentials at the respective supply terminals of its module for providing an output signal at its output terminal, and warning means operatively coupled with the output terminal of failsafe circuit means of the last succeeding skid control module for providing a warning when an output signal does not appear at the output terminal of said last-mentioned failsafe circuit means, each failsafe circuit means comprising an electronic switch means having three terminals, means operatively coupling each of said three terminals of said electronic switch means with said first and second supply terminals and with said input terminal such that said electronic switch means is actuated only when an input signal is present at said input terminal and the first and second reference potentials are present at said first and second supply terminals and means responsive to actuation of said electronic switch means for supplying an output signal at the output terminal when said electronic switch means is actuated.

4. The invention as claimed in claim 3 wherein said means responsive to actuation of said electronic switch means for supplying said output signal at said output terminal comprises a second electronic switch means operatively coupled with said first-mentioned electronic switch means and an output circuit operatively coupling said second electronic switch means with said output terminal, said second electronic switch means being operatively coupled with said first electronic switch such that said second electronic switch means is actuated in response to actuation of said first electronic switch means.

5. The invention as claimed in claim 4 wherein said output circuit operatively coupled with said second electronic switch means comprises a voltage dividing circuit and said output signal at said output terminal is developed by said voltage dividing circuit as a fraction of the difference between said first reference Potential and said second reference potential relative to one of said reference potentials.

6. In a multi-axle wheeled vehicle having a plurality of skid control modules with each skid control module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels of the associated axle and first and second supply terminals to which first and second reference potentials are intended to be respectively supplied, and including supply means for supplying said first and second reference potentials, the invention wherein each said skid control module further includes a failsafe circuit means having an input terminal to which an input signal is intended to be supplied and an output terminal which is intended to supply an output signal, means for supplying an input signal to the input terminal of one of said failsafe circuit means, means for operatively coupling the output terminal of each preceding failsafe circuit means to the input terminal of the succeeding failsafe circuit means whereby an output signal from the failsafe circuit means of a preceding skid control module is supplied as the input signal to the failsafe circuit means of a succeeding skid control module, each said failsafe circuit means comprising means responsive to the presence of an input signal at its input terminal and the presence of the respective reference potentials at the respective supply terminals of its module for providing an output signal at its output terminal, and warning means for providing a warning when an output signal does not appear at the output terminal of said last-mentioned failsafe circuit means, said warning means comprising an indicating element having a pair of terminals, one of said indicating element terminals being operatively coupled with said output terminal of the last failsafe circuit means and the other terminal of said indicating element being operatively coupled with one of said first and second reference potentials, said failsafe circuit means being operative when providing an output signal at its output terminal to prevent said indicating element from being energized via said one reference potential and when an output signal is absent at its output terminal operative to permit said indicating element to be energized via said one reference potential.

7. The invention as claimed in claim 6 wherein said failsafe circuit means comprises switch means, means operatively coupling said switch means between the output terminal and one of the supply terminals of the failsafe circuit means, said switch means being actuated in response to the absence of a signal at the output terminal to cause current to be conducted through said indicating element.

8. The invention as claimed in claim 7 wherein said switch means comprises a transistor means.

9. In a multi-axle wheeled vehicle having a plurality of skid control modules with each module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels of the associated axle and including means for supplying a potential difference to each skid control module, the invention wherein each said skid control module comprises a failsafe circuit means, each said failsafe circuit means having an input terminal and an output terminal, means for cascading the failsafe circuit means of successive skid control modules such that the output terminal of eacch preceding failsafe circuit means is operatively coupled with the input terminal of the succeeding failsafe circuit means whereby a signal at the output terminal of each failsafe circuit means is supplied as an input signal to the input terminal of the succeeding failsafe circuit means, warning means operatively coupled with the output terminal of the failsafe circuit means of the last of the cascaded failsafe circuit means, means for providing a signal to the input terminal Of the first of the cascaded failsafe circuit means, each said failsafe circuit means comprising means responsive to the presence of a signal at its input terminal and to the presence of said potential difference at its module for providing a signal at its output terminal only when both said signal at its input terminal and said potential difference are present, said warning means providing a warning when a signal fails to appear at the output terminal of the last of said failsafe circuit means so as to indicate when either said input signal or said potential difference at any one of said failsafe circuit means is not present.

10. In a multi-axle wheeled vehicle having a plurality of skid control modules with each module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels of the associated axle and including means for supplying a potential difference to each skid control module, the invention wherein each said skid control module comprises a failsafe circuit means, each said failsafe circuit means having an input terminal and an output terminal means for cascading the failsafe circuit means of successive skid. control modules such that the output terminal of each preceding failsafe circuit means is operatively coupled with the input terminal of the succeeding failsafe circuit means whereby a signal at the output terminal of each failsafe circuit means is supplied as an input signal to the input terminal of the succeeding failsafe circuit means, warning means operatively coupled with the output terminal of the failsafe circuit means of the last of the cascaded failsafe circuit means, means for providing a signal to the input terminal of the first of the cascaded failsafe circuit means, each said failsafe circuit means comprising means responsive to the presence of a signal at its input terminal and to the presence of said potential difference at its module for providing a signal at its output terminal, said warning means providing a warning when a signal fails to appear at the output terminal of the last of said failsafe circuit means, each said failsafe circuit means comprising a transistor having base, emitter and collector terminals, means operatively coupling the base terminal with the input terminal, means operatively coupling the emitter and collector terminals with said potential difference including a second transistor having base emitter and collector terminals, said failsafe circuit means further including a voltage divider output circuit operatively coupling the emitter-collector circuit of the second transistor with said potential difference, the base terminal of said second transistor being operatively coupled with the emitter-collector circuit of the first transistor, each said failsafe circuit means being operative upon application of an input signal to the input terminal such that the first transistor is actuated to in turn actuate the second transistor, the second transistor causing an output signal to appear across the voltage divider circuit, said voltage divider circuit providing at the output terminal an output signal equal to a fraction of said potential difference.

11. The invention as claimed in claim 10 wherein said first transistor is rendered conductive when the input signal is applied to the input terminal.

12. The invention as claimed in claim 11 wherein the second transistor is rendered conductive in response to conduction of the first transistor.

13. The invention as claimed in claim 12 wherein the voltage divider circuit is operatively coupled with said potential difference also through the emitter-collector circuit of said first transistor.

14. In a multi-axle wheeled vehicle having a plurality of skid control modules with each skid control module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels Of the associated axle, and including means for supplying a potential difference to each said skid control module, the invention wherein each skid control module comprises a failsafe circuit means, each said failsafe circuit means having an input circuit means and an output circuit means, means for successively cascading the failsafe circuit means of said skid control modules so that said failsafe circuit means form a chain along which a signal may be propagated, means for supplying said signal to the input circuit means of the first failsafe circuit means in the chain, each said failsafe circuit means comprising means responsive to the presence of said signal at its input circuit means and to the presence of said potential difference at its module for causing said signal to appear at its output circuit means and to thus be supplied to the input circuit means of the immediately succeeding failsafe circuit means in the chain only when both said signal at its input circuit means and said potential difference are present and warning means operatively coupled with the output circuit means of the last failsafe circuit means in the chain providing a warning when said signal fails to propagate along the chain to the output circuit means of said last failsafe circuit means in the chain so as to indicate when either said signal is not received at the input of one of said failsafe circuit means or said potential difference is not present at one of said failsafe circuit means.

15. In a multi-axle wheeled vehicle having a plurality of skid control modules with each skid control module being operatively associated with one of the axles of the vehicle, each said skid control module comprising a skid control circuit means for skid controlling the wheels of the associated axle, and including means for supplying a potential difference to each said skid control module, the invention wherein each skid control module comprises a failsafe circuit means, each said failsafe circuit means having an input circuit means and an output circuit means, means for successively cascading the failsafe circuit means of said skid control modules so that said failsafe circuit means form a chain along which a signal may be propagated, means for supplying said signal to the input circuit means of the first failsafe circuit means in the chain, each said failsafe circuit means comprising means responsive to the presence of said signal at its input circuit means and to the presence of said potential difference at its module for causing said signal to appear at its output circuit means and to thus be supplied to the input circuit means of the immediately succeeding failsafe circuit means in the chain and warning means operatively coupled with the output circuit means of the last failsafe circuit means in the chain providing a warning when said signal fails to progagate along the chain to the output circuit means of said last failsafe circuit means in the chain, aech said failsafe circuit means further comprising a first transistor having base emitter and collector terminals, means operatively coupling the base terminal to receive the input signal to the failsafe circuit, means operatively coupling the emitter and collector terminals with said potential difference including a second transistor having base emitter and collector terminals, said failsafe circuit means further including a voltage divider output circuit operatively coupling the emitter-collector circuit of the second transistor with said potential difference, the base terminal of said second transistor being operatively coupled with the emitter-collector circuit of the first transistor, each said failsafe circuit means being operative upon application of an input signal to the base terminal of the first transistor such that the first transistor is actuated to in turn actuate the second transistor, the second transistor causing an output signal to appear across the voltage divider circuit, said voltage divider circuit providing at the output circuit an output sIgnal equal to a fraction of said potential difference.

16. The invention as claimed in claim 15 wherein said first transistor is rendered conductive when the input signal is applied to the base terminal of the first transistor.

17. The invention as claimed in claim 15 wherein the second transistor is rendered conductive in response to conduction of the first transistor.

18. The invention as claimed in claim 17 wherein said warning means comprises an indicating element having a pair of terminals, one of which is coupled with the output circuit means of the last failsafe circuit and the other of which is coupled with a source of power, said indicating element being operative to provide a warning indication in response to non-conduction of said first and second transistors.