Apparatus and method for monitoring tire condition

• US 20020073771A1
• Filed: 09/20/2001
• Published: 06/20/2002
• Est. Priority Date: 12/15/2000
• Status: Active Grant

• Current Assignee: Pacific Industrial Company Limited
• Original Assignee: Pacific Industrial Company Limited
• Inventors: Katou, Michiya
• Granted Patent: US 6,705,155 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0416 allocating a corresponding wheel position on vehicle, e.g. front/left or rear/right
• CPC Class Codes: B60C 23/0444 Antenna structures, control or arrangements thereof, e.g. for directional antennas, diversity antenna, antenna multiplexing or antennas integrated in fenders
• CPC Class Codes: B60C 23/0459 self triggered by motion sensor
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: B60C 23/0464 to avoid signal interference
• CPC Class Codes: B60C 23/0489 for detecting the actual angular position of the monitoring device while the wheel is turning

Abstract

A transmitter device includes a rotational direction sensor that generates a specific pattern signal when a corresponding tire rotates. The pattern signal of the left tires is different from the pattern signal of the right tires. A front reception antenna is near the front tires. A rear reception antenna is near the rear tires. A receiver includes a switch circuit that selectively connects the front reception antenna or the rear reception antenna to a controller. When one transmitter device transmits a radio signal, the controller determines which transmitter device is the source of the radio signal in accordance with the level of the signals from the reception antennas and the pattern signal, which is included in the data transmitted by the transmitter device.

Claims

1. A tire condition monitoring apparatus for monitoring the condition of a plurality of tires attached to a vehicle, wherein the tires include left and right front tires and left and right rear tires, the apparatus comprising:

a transmitter device, which is attached to each tire, wherein the transmitter device has a condition sensor that detects the condition of the corresponding tire and a signal generator that generates a specific pattern signal when the tire rotates, wherein the pattern signal generated by the signal generator of the transmitter device attached to each left tire is different from the pattern signal generated by the signal generator of the transmitter device attached to each right tire when the vehicle moves in a given direction, and each transmitter device transmits a radio signal that includes data that represents the tire condition and data that represents the pattern signal;

a front reception antenna, which is installed in a body of the vehicle at a position that is relatively near to the left and right front tires, wherein the front reception antenna receives radio signals from the transmitter devices;

a rear reception antenna, which is installed in the vehicle body at a position that is relatively near to the left and right rear tires, wherein the rear reception antenna receives radio signals from the transmitter devices; and

a receiver, which receives reception signals from the front and rear reception antennas, wherein the receiver includes a controller, and wherein, when one of the transmitter devices has transmitted a radio signal, the controller determines which transmitter device has transmitted the radio signal in accordance with the level of reception signals from the reception antennas and the data that represents the pattern signal, which is included in the radio signal transmitted by the transmitter device.

2. The apparatus as set forth in claim 1, wherein the receiver further includes a switch circuit that selectively connects the front reception antenna or the rear reception antenna to the controller.

3. The apparatus as set forth in claim 1, wherein each signal generator generates a first pattern signal when the corresponding tire rotates in one direction, and each signal generator generates a second pattern signal, which is different from the first pattern signal, when the tire rotates in the other direction.

4. The apparatus as set forth in claim 3, wherein the signal generators that correspond to the left front and rear tires generate the first pattern signals and the signal generators that correspond to the right front and rear tires generate the second pattern signals if the vehicle moves forward, and the signal generators that correspond to the left front and rear tires generate the second pattern signals and the signal generators that correspond to the right front and rear tires generate the first pattern signals if the vehicle moves rearward.

5. The apparatus as set forth in claim 3, wherein each signal generator includes:

a case, in which an annular passage is formed; and

a movable body, which is located in the annular passage, wherein the movable body moves in the annular passage circumferentially in the case when the corresponding tire rotates, and the direction in which the movable body moves changes in accordance with the direction in which the tire rotates.

6. The apparatus as set forth in claim 5, wherein each signal generator generates the first pattern signal when the movable body moves in one direction and generates the second pattern signal when the movable body moves in the other direction.

7. The apparatus as set forth in claim 5, wherein the movable body is formed of a conductive material, and each signal generator further includes a pair of annular electrode plates, which are located in the annular passage and are electrically connected to each other through the movable body, and at least one electrode plate includes a plurality of non-conductive portions, each of which is circumferentially spaced from the adjacent non-conductive portion, by a predetermined interval, and the electrode plates are not electrically connected to each other when the movable body is located at a position corresponding to one of the non-conductive portions.

8. The apparatus as set forth in claim 7, wherein the non-conductive portions are cut-away portions formed in one electrode plate, and the cut-away portions divide the electrode plate into a plurality of sections, and the sections have different circumferential dimensions.

9. The apparatus as set forth in claim 1, wherein the controller determines which transmitter device has transmitted the radio signal in accordance with the direction of movement of the vehicle.

10. The apparatus as set forth in claim 1, wherein the controller first determines whether the front or the rear tires correspond to the reception antenna that generates the highest level signal, and the controller subsequently determines which of the transmitter devices of the determined tires has transmitted the radio signal, in accordance with the data that represents the pattern signal, which is included in the radio signal transmitted by the transmitter device.

11. A tire condition monitoring apparatus for monitoring the condition of a plurality of tires attached to a vehicle, wherein the tires include left and right front tires and left and right rear tires, the apparatus comprising:

a transmitter device, which is attached to each tire, wherein the transmitter device includes;

a condition detecting means for detecting the condition of the corresponding tire;

a signal generating means for generating a specific pattern signal when the tire rotates, wherein the pattern signal generated by the signal generating means of the transmitter device attached to each left tire is different from the pattern signal generated by the signal generating means of the transmitter device attached to each right tire when the vehicle moves in a given direction; and

a transmitting means for transmitting a radio signal, the radio signal including data that represents the tire condition and data that represents the pattern signal;

a front reception antenna, which is installed in a body of the vehicle at a position that is relatively near to the left and right front tires, wherein the front reception antenna receives radio signals that are relatively strong from the transmitter devices of the left and right front tires;

a rear reception antenna, which is installed in the vehicle body at a position that is relatively near to the left and right rear tires, wherein the rear reception antenna receives radio signals that are relatively strong from the transmitter devices of the left and right rear tires;

a control means for receiving reception signals from the front reception antenna and the rear reception antenna; and

a switch means for selectively connecting the front reception antenna or the rear reception antenna to the control means, wherein, when one of the transmitter devices has transmitted a radio signal, the control means determines which transmitter device has transmitted the radio signal in accordance with the level of reception signals from the reception antennas and the data that represents the pattern signal, which is included in the radio signal transmitted by the transmitter device.

12. The apparatus as set forth in claim 11, wherein each signal generating means includes:

a case, in which an annular passage is formed; and

a movable body, which is located in the annular passage, wherein the movable body rolls in the annular passage circumferentially in the case when the corresponding tire rotates, and the direction in which the movable body rolls changes in accordance with the direction in which the tire rotates.

13. The apparatus as set forth in claim 12, wherein each signal generating means generates a first pattern signal when the movable body rolls in one direction and generates a second pattern signal, which is different from the first pattern signal, when the movable body rolls in the other direction.

14. The apparatus as set forth in claim 12, wherein the movable body is formed of a conductive material, and each signal generating means further includes a pair of annular electrode plates, which are located in the annular passage and are electrically connected to each other through the movable body, and at least one electrode plate includes a plurality of non-conductive portions, each of which is circumferentially spaced from the adjacent non-conductive portion, by a predetermined interval, and the electrode plates are not electrically connected to each other when the movable body is located at a position corresponding to one of the non-conductive portions.

15. The apparatus as set forth in claim 14, wherein the non-conductive portions are cut-away portions formed in one electrode plate, and the cut-away portions divide the electrode plate into a plurality of sections, and the sections have different circumferential dimensions.

16. The apparatus as set forth in claim 11, wherein the control means determines which transmitter device has transmitted the radio signal in accordance with the direction of movement of the vehicle.

17. The apparatus as set forth in claim 11, wherein the control means first determines whether the front or the rear tires correspond to the reception antenna that generates the highest level signal, and the control means subsequently determines which of the transmitter devices of the determined tires has transmitted the radio signal, in accordance with the data that represents the pattern signal, which is included in the radio signal transmitted by the transmitter device.

18. A tire condition monitoring method for monitoring the condition of a plurality of tires attached to a vehicle, wherein the tires include left and right front tires and left and right rear tires, the method comprising:

detecting the condition of each tire;

generating a specific pattern signal for each tire when the tires rotate, wherein the pattern signal generated for each left tire is different from the pattern signal generated for each right tire;

transmitting a radio signal from one of the tires, the radio signal including data that represents the tire condition and data that represents the pattern signal;

receiving the radio signal at a front location that is relatively near to the front tires;

receiving the radio signal at a rear location that is relatively near to the rear tires; and

determining which tire has transmitted the radio signal in accordance with the level of signals received at the front and rear locations and the data that represents the pattern signal, which is included in the transmitted radio signal.