Patent Application
20090066497
The present invention relates generally to a tire pressure monitoring system and more particularly to a tire pressure monitoring system using dual antennas with a single receiver module.
Automotive design has adapted to incorporate an ever increasing range of convenience and safety features. These features are located throughout the vehicle. While many of the electronic features are positioned with easy access to centralized processors, there are some features whose location and functionality requires remote location.
One such feature is the tire pressure monitoring system. These system must register pressure within a vehicles tire. As such, the sensors within the rotating wheel must communicate wirelessly with a remote receiver. Furthermore, the receiver must have the ability to discriminate from the sensor in each wheel independently to properly inform the driver. Therefore, existing systems often incorporate complex signal triggers and identification signals to isolate one pressure sensor signal from another. These sensors are costly and complex. Furthermore, replacement during the vehicle life cycle can require costly reconfiguration of the main receiver system.
An additional concern involves the standardization of pressure sensor signal frequencies. As the majority of vehicles begin to utilize TPM systems operating at identical frequencies, simultaneous transmissions from nearby vehicles can result in radio frequency collisions that lose the tire data. It would be highly desirable to reduce the power of the sensor signals in order to reduce incidents of interference.
As such it would be highly desirable to have a tire pressure monitoring system that could be inexpensively and simply implemented. It would also be highly desirable for such a tire pressure monitoring system to minimize the chance for interference with nearby vehicles.
In accordance with the desires of the present invention an automotive tire pressure monitoring system is provided including a group of tire pressure monitor sensors each comprising a pressure sensor element, a dual-axis accelerometer, and a transmitter generating a pressure signal including accelerometer information. A front antenna and a rear antenna are both in communication with a tire pressure monitoring receiver. The tire pressure monitoring receiver includes logic adapted to: determine a pressure signals left/right designation from the accelerometer information and determine a pressure signal's front/rear designation using comparative signal strength from the front antenna and the rear antenna.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description and preferred embodiment when taken in conjunction with the attached drawings and claims.
Referring now to
The tire pressure monitoring system 10 includes a group of tire pressure monitor sensors 22 each of which comprises a pressure sensor element 24, a dual-axis accelerometer 26, and a transmitter 28. (See
The group of tire pressure monitor sensors 22 are preferably trigger less sensors who do not require an initiator signal to broadcast. This significantly reduces their complexity and cost. In addition, the sensors 22 preferably incorporate low power transmission such that their effective transmission radius 56 is less than a vehicle width 58 to minimize interference with nearby vehicles. In at least one embodiment it is contemplated that the transmission radius 56 be between half a vehicle width 58 and a vehicle width 58.
The present invention incorporates a tire pressure monitoring receiver 60 mounted within the automobile 12. The tire pressure monitoring receiver 60 is in communication with a front antenna 62 and a rear antenna 64. The front antenna is preferably mounted near the vehicle centerline 66 in close proximity to the right front tire pressure sensor 32 and the left front tire pressure sensor 38. The rear antenna 64 is preferably mounted near the vehicle centerline 66 in close proximity to the right rear tire pressure sensor 44 and the left rear tire pressure sensor 50. In one embodiment it is contemplated that the rear antenna 64 may be mounted within the vehicle trunk 68. Although the front antenna 62 and the rear antenna 64 may be independent and mounted remotely from the tire pressure monitoring receiver 60, in is contemplated that one of them may be integrated into the tire pressure monitoring receiver 60. In
The tire pressure monitoring receiver 60 receives signals 36,42,48,54 from the front antenna 62 and the rear antenna 64. The tire pressure monitoring receiver 60 incorporates logic adapted to determine the signals front/rear designation using comparative signal strength from the front antenna 62 and rear antenna 64. In one embodiment this is contemplated to be achieved through the use of a simple received signal strength indicator circuitry (RSSI). In another embodiment it is contemplated that the tire pressure monitoring receiver 60 includes a switch element 70. The switch element 70 allows the tire pressure monitoring receiver 60 to independently poll the front antenna 62 and rear antenna 64 to determine comparative signal strength. This allows the tire pressure monitoring receiver 60 to determine of the signal come from the front sensors 32,38 or the rear sensor 44,50.
The tire pressure monitoring receiver 60 further includes logic adapted to determine the signals left/right designation from the accelerometer information contained in the pressure signal 30. The accelerometer information produced by the dual-axis accelerometer 26 will vary dependent on vehicle dynamics and the left/right designation of the sensor. By way of example, during a left hand turn the right front dual-axis accelerometer 34 will experience a greater rotational speed than the left front dual-axis accelerometer 40. In this fashion, it is possible for the logic to determine a left/right designation from the accelerometer information contained in the pressure signal 30.
The present invention accomplishes pressure sensor signal location without complex sensors or unique identification signals. The present invention allows for the use of trigger less sensors and removes the necessity of initiator signals. Finally, the present invention allows for the use of low power transmissions which reduce interference with nearby vehicles.
While the invention has been described in connection with one or more embodiments, it is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of the principles of the invention, numerous modifications may be made to the methods and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.
