Tire pressure monitoring system transmission protocol

• US 7,095,316 B2
• Filed: 11/15/2002
• Issued: 08/22/2006
• Est. Priority Date: 11/15/2001
• Status: Expired due to Term

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Kachouh, Patricia, Desai, Tejas B., VanDrus, Kurt
• Primary Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US10/298,058
• Publication Number:
  US 20030122660A1
• Time in Patent Office: 1,376 Days
• Field of Search: 340/442, 340/445, 340/447, 340/448, 340/449, 340/426.17, 340/426.36, 340/5.61, 340/5.6, 340/5.64, 340/10.1, 340/10.5, 340/825.69, 340/826.58, 340/10.2, 731/462, 731/465, 731/468, 731/46
• US Class Current: 340/442
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: B60C 23/0464 to avoid signal interference

Abstract

A system for monitoring conditions within a tire includes a sensor assemblies (14). The sensor assemblies (14) emit a transmission (26) containing information indicative of conditions within a tire to a receiver (16). The transmission (26) from the sensor assemblies (14) includes an amplitude shift key wake up portion and various data packet portions. The data packet portions are separated by a variable interval to prevent collisions of transmissions at the receiver.

Claims

1. A system for monitoring conditions within a tire comprising;

a sensor disposed within a tire for sensing conditions within said tire;

a transmitter for transmitting a signal indicative of conditions within said tire;

a receiver for receiving said signal;

said signal indicative of conditions within a tire includes a first preamble portion and at least one data packet portion wherein there is a variable interval between the at least one data packet portions, wherein said variable interval varies according to the equation Interval length=Standard length+(beta * standard length)

Where;

interval length is the length of time in ms between data frames;

standard length is a predetermined duration of time in ms; and

Beta is a random variable with a value between 0 and 1.

2. The system of claim 1, wherein said preamble portion includes an Amplitude Shift Keyed wake up signal.

3. The system of claim 1, wherein said plurality of data packets are transmitted in Frequency Shift Keyed format.

4. The system of claim 1, wherein said plurality of data packets include a data preamble including 15 data zero bits and one start bit having a data value of “

1”

.

5. The system of claim 1, wherein said plurality of data packets include an identification code.

6. The system of claim 1, wherein said plurality of data packets includes an identification number including device serial number and product type.

7. The system of claim 1, wherein said plurality of data packets includes pressure information indicative of pressure within said tire.

8. The system of claim 1, wherein said plurality of data packets includes temperature information indicative of temperature within said tire.

9. The system of claim 1, wherein said plurality of data packets include status information indicative of current operational conditions of said sensor.

10. The system of claim 9, wherein said status information includes information indicative of a low battery condition.

11. The system of claim 1, wherein said signal indicative of tire conditions is initiated at predetermined intervals.

12. The system of claim 11, wherein said signal indicative of tire conditions is initiated at intervals shorter than said predetermined intervals in response to a desired rate of change of any conditions monitored within the tire.

13. The system of claim 1, wherein said time interval between said plurality of data packets is variable.

14. The system of claim 13, wherein said variable time interval varies between 100 milliseconds and 200 milliseconds.

15. The system of claim 1, including a check sum data packet including a binary value equivalent to a decimal sum of all data bits.

16. The system of claim 1, including a low battery bit set to a value of “

0”

when at battery voltage is within a predetermined range, and set to a value of “

1”

when out of said predetermined range.

17. The system of claim 2 wherein said wake up portion includes a pattern selected to minimize duty cycle.

18. The system of claim 1, including four bits indicating specific wake up status codes.

19. The system of claim 18, wherein said wake up status codes indicates a status of said sensor, said status includes learn, Normal, Over temp, Wake and LF.

20. The system of claim 1, including transmitting said signal at predetermined intervals in response to movement of the motor vehicle.

21. The system of claim 1, including increasing the duration between transmissions of signals in response to the motor vehicle decreasing in speed below a predetermined speed.

22. The system of claim 1, including at receiver for receiving ASK signals and FSK signals.

23. The system of claim 22, wherein said receiver defaults to receiving ASK signals.

24. The system of claim 22, wherein said receiver receives ASK signals from a remote keyless entry system.

25. The system of claim 1, wherein each of said plurality of data packets includes a time interval value indicating when transmission of a subsequent one of said plurality of data packets will occur.