Level control system for a motor vehicle

• US 6,224,044 B1
• Filed: 01/20/2000
• Issued: 05/01/2001
• Est. Priority Date: 01/20/1999
• Status: Expired due to Term

• Current Assignee: Continental AG
• Original Assignee: Continental AG
• Inventors: Sommer, Stefan, Matthies, Thomas, Heilenkotter, Carsten
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): NGUYEN, XUAN LAN T
• Application Number:
  US09/487,873
• Time in Patent Office: 467 Days
• Field of Search: 188/322.5, 267/64.16, 303/3, 303/15, 280/735, 280/6.15, 280/5.5
• US Class Current: 267/64.16
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 2500/2012 Open systems
• CPC Class Codes: B60G 2500/30 Height or ground clearance

Abstract

The invention is directed to a level control system for a motor vehicle wherein the controllable valves (8a to 8d and 10) are controlled by a first control unit (24). The first control unit (24) transmits a signal to a second control unit (36) at time intervals. If the second control unit (36) does not receive the signal expected from the first control unit, then the second control unit (36) assumes the control of the valves (8a to 8d and 10) in such a manner that the motor vehicle is transferred into a dynamically safe driving condition.

Claims

1. A level control system for a motor vehicle, the system comprising:

a plurality of air springs;

a plurality of controllable first valves connected to corresponding ones of said air springs for filling and venting the respective air springs;

a controllable second valve switchable to connect said air springs to the atmosphere for venting said air springs;

a first control unit for controlling said controllable first and second valves to fill or vent said air springs;

a second control unit for controlling said controllable first and second valves to fill or vent said air springs;

said first control unit having means for transmitting check signals to said second control unit at respective time intervals; and

,

said second control unit having checking means for checking whether said second control unit receives each of said check signals from said first control unit and, when one of said signals expected from said first control unit is not received, said second control unit functioning to assume control of said controllable first and second valves so as to drive said first and second valves to bring said motor vehicle into a dynamically safe driving condition.

2. The level control system of claim 1, wherein said second control unit functions to open said controllable first and second valves so as to cause each of said air springs to be connected to the atmosphere when said second control unit does not receive the expected signal from said first control unit.

3. The level control system of claim 2, wherein said second control unit functions to open said controllable first and second valves to maintain a condition wherein each of said air springs is connected to the atmosphere over a pregiven time span;

and, after said time span elapses, said second control unit functions to close said controllable first and second valves; and

, said pregiven time span being so dimensioned that said air springs are emptied to the extent that said motor vehicle assumes the lowest possible level within said pregiven time span.

4. The level control system of claim 1, wherein said system further comprises at least one elevation sensor which generates an elevation signal dependent upon the level of said motor vehicle;

said second control unit functioning to evaluate said elevation signal of said elevation sensor at least in those time spans during which said second control unit assumes the control of said controllable first and second valves; and

,

said second control unit functioning to open said controllable first and second valves and connect all of said plurality of air springs to the atmosphere until the evaluation of said elevation signal indicates that said motor vehicle is in a pregiven dynamically safe elevation region when;

(a) said second control unit does not receive the check signal expected from said first control unit; and

,

(b) the evaluation of said elevation signal shows that the level of said motor vehicle lies above a pregiven level.

5. The level control system of claim 4, further comprising:

said second control unit functioning to continuously evaluate said elevation signal of said elevation sensor;

said second control unit further functioning to open said controllable first and second valves and to so connect said plurality of air springs to the atmosphere until the evaluation of said elevation signal shows that said motor vehicle is in a pregiven dynamically safe elevation region when the evaluation of said elevation signal shows that the level of said motor vehicle lies above a pregiven level independently of whether said check signal expected from said first control unit is received.

6. The level control system of claim 1, wherein said second control unit functions to transmit additional signals to said first control unit at time intervals;

said first control unit including checking means for checking whether said first control unit receives each of said additional signals from said second control unit and said first control unit functioning to actuate a warning device when said first control unit does not receive said additional signal expected from said second control unit.

7. The level control system of claim 1, said checking means in said second control unit including a continuously counting counter which is reset by each of said check signals transmitted from said first control unit;

and, said second control unit assuming the control of said controllable first and second valves when the count of said counter exceeds a predetermined value.