WO2013132960A1

WO2013132960A1 - Tire condition monitor device

Info

Publication number: WO2013132960A1
Application number: PCT/JP2013/053102
Authority: WO
Inventors: 勝宏清野
Original assignee: アルプス電気株式会社
Priority date: 2012-03-06
Filing date: 2013-02-08
Publication date: 2013-09-12

Abstract

The purpose of the present invention is to reduce the number of low-frequency (LF) antennas and reduce costs while improving the degree of freedom in vehicle body layout. A tire condition monitor device comprises sensor units (13A-13D) respectively provided on front wheels (12A, 12B) and rear wheels (12C, 12D); an LF antenna (15) that transmits a response request signal to the sensor units (13A-13D) which requests a response from the sensor units; and an on-car device (14). The communication area of the LF antenna (15) is set such that one wheel group is located inside the communication area while the other wheel group is located outside the communication area. The on-car device (14) determines wheels in accordance with whether or not the sensor signals received from each of the sensor units (13A-13D) are synchronized with said response request signal and the rotational direction information of the wheels.

Description

Tire condition monitoring device

The present invention relates to a tire condition monitoring device that monitors tire information through wireless communication between a plurality of sensor units provided on a front wheel and a rear wheel of a vehicle and a vehicle body side device.

Conventionally, in vehicles such as automobiles, TPMS (Tire Pressure Monitoring System) for monitoring tire conditions such as air pressure and temperature of tires constituting wheels has been known. In TPMS, a sensor unit having a sensing function for detecting a tire condition and a wireless communication function is directly attached to each wheel, and a vehicle body side device that wirelessly communicates with the sensor unit of each wheel is provided on the vehicle body side. The vehicle body side device monitors the tire condition of each wheel based on the sensor signal received from the sensor unit of each wheel, detects an abnormality in the tire condition, and notifies the user.

In such TPMS, it is necessary for the vehicle body side device to specify the sensor unit (wheel) that is transmitting the sensor signal indicating the tire condition. For this reason, the TPMS performs wheel determination that associates the sensor unit with the wheel to which the sensor unit is attached. For example, at the timing when the ignition switch for starting the engine is turned on from OFF, wheel determination processing is performed to associate sensor identification information for identifying the sensor unit with the position of the wheel on which the sensor unit is provided (for example, Patent Document 1).

The tire condition monitoring device of Patent Document 1 includes a first transmission antenna that is provided at the front of the vehicle body and used for determining the front wheel, and a second transmission antenna that is provided at the rear of the vehicle body and used for determining the wheel of the rear wheel. The side device receives a sensor signal from the front wheel sensor unit or a sensor signal from the rear wheel sensor unit. Based on the RSSI (Received Signal Strength Strength Indication) of the received sensor signal, the control device of the vehicle body side device identifies the position of the wheel to which the sensor unit that transmitted the signal is attached. Specifically, the first transmission antenna and the second transmission antenna are respectively installed at eccentric positions in the axle direction (left-right direction). And the sensor unit which received the LF signal from the 1st antenna with the front wheel sensor unit received with the receiving antenna on the vehicle body side, and transmitted the sensor signal based on the RSSI of the received sensor signal Is attached to the left or right front wheel. Similarly, the sensor unit that receives the LF signal from the second antenna by the rear wheel sensor unit receives the sensor signal at the receiving antenna, and transmits the sensor signal based on the RSSI of the received sensor signal. Determine whether it is attached to the left or right rear wheel. The control device stores the identified wheel position and the identification information of the sensor unit in the storage unit in association with each other.

JP 2009-214708 A

However, since the tire condition monitoring device of Patent Document 1 is provided with the first antenna corresponding to the front wheel sensor unit and the second antenna corresponding to the rear wheel sensor unit, the four wheels on the front, rear, left and right are provided. In order to determine the above, it is necessary to provide at least two antennas on the front and rear of the vehicle body. For this reason, there is a problem in that the cost for installing two antennas is high, and restrictions on the antenna installation are large, and the degree of freedom in layout of the vehicle body is reduced.

The present invention has been made in view of the above points, and can reduce the number of antennas that transmit response request signals for requesting responses to the wheel sensor units, thereby reducing costs and freeing the layout of the vehicle body. It is an object to provide a tire condition monitoring device capable of improving the degree.

A tire condition monitoring device according to the present invention includes a plurality of sensor units provided respectively on front wheels and rear wheels constituting a vehicle wheel, and a vehicle body side antenna that transmits a response request signal for requesting a response to the sensor unit. A vehicle body side device that wirelessly communicates with each sensor unit, and the vehicle body side antenna receives the response request signal from a front wheel or a rear wheel closer to the vehicle body side antenna, and the vehicle body side The front wheel or the rear wheel on the side far from the antenna is arranged so as not to receive the response request signal, and each of the sensor units transmits the sensor signal including the sensor identification information by the vehicle body side antenna. Asynchronously with the signal, the signal is transmitted to the vehicle body side device, and if the response request signal is received, a sensor signal including sensor identification information is used as the response request signal. The sensor units are arranged so that rotational direction information indicating the rotational directions of the left and right wheels of the front wheel and the rear wheel is different from each other, and detects the rotational direction of the wheels. A sensor signal including rotation direction information indicating the detected wheel rotation direction and sensor identification information is transmitted to the vehicle body side device, and the vehicle body side device is included in the sensor signal received in synchronization with the response request signal. From the detected sensor identification information, the wheel closer to the vehicle body side antenna is determined, and from the sensor identification information included in the sensor signal received asynchronously to the response request signal, the wheel far from the vehicle body side antenna is determined. The left and right wheels are determined from the rotational direction information included in the sensor signal.

According to this configuration, the communication area is set so that the wheel group closer to the antenna transmitting the response request signal enters the communication area and the wheel group far from the antenna does not enter the communication area. Depending on whether or not the received sensor signal is synchronized with the response request signal, the distance between the wheel and the vehicle body side antenna is determined, and the left and right are determined by the wheel rotation direction. The number can be reduced to one, and the cost can be reduced and the degree of freedom of the layout of the vehicle body can be improved. Note that “synchronization” described in the present specification means that a plurality of signals have the same period and the same phase.

Each sensor unit transmits a sensor signal asynchronously with the response request signal in a first cycle, and the vehicle body side antenna requests a response in a second cycle shorter than the first cycle until the wheel is determined. It is desirable to transmit a signal. According to this configuration, since the second period is shorter than the first period, the wheel can be determined in a short time. Further, the vehicle body side antenna may be installed at a front portion of the vehicle. According to this configuration, the distance difference between the wheel group on the side closer to the vehicle body side antenna and the wheel group on the side far from the vehicle body side antenna can be increased compared with the case where the vehicle body side antenna is arranged in the center of the vehicle. A wheel group that cannot communicate with a wheel group that cannot communicate with each other can be reliably identified.

According to the present invention, it is possible to reduce the number of vehicle body side antennas that transmit a response request signal for requesting a response to the wheel sensor unit, thereby reducing the cost and improving the degree of freedom of the vehicle body layout.

1 is an overall configuration diagram of a tire condition monitoring device according to the present embodiment. It is a detailed functional block diagram of the tire condition monitoring apparatus which concerns on this Embodiment. It is a figure for demonstrating the example of a detection of the rotation direction of the wheel which concerns on this Embodiment. It is a figure for demonstrating the relationship between reception of the UHF signal which concerns on this Embodiment, and transmission of LF signal. It is a figure which shows the memory content of the memory | storage part which matched and memorize | stored sensor identification information and wheel identification information. It is a flowchart for wheel decision in this Embodiment.

Hereinafter, the tire condition monitoring apparatus according to the present embodiment will be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of a tire condition monitoring apparatus according to the present embodiment. 1 shows a configuration in which the tire condition monitoring device of the present embodiment is applied to a four-wheel vehicle 10. The vehicle 10 includes a vehicle body 11 and four wheels 12A to 12D attached to the vehicle body 11. In the following description, the direction of the arrow FR is the front of the vehicle 10, and the direction of the arrow BK opposite to the arrow FR is the rear of the vehicle 10. Further, as appropriate, the

wheels

12A and 12B attached to the front of the vehicle body 11 are referred to as

front wheels

12A and 12B, and the

wheels

12C and 12D attached to the rear of the vehicle body 11 are referred to as

rear wheels

12C and 12D.

The tire condition monitoring device includes sensor units 13A to 13D attached to the wheels 12A to 12D, a control device 14 as a vehicle body side device provided at a predetermined position (for example, near the center) of the vehicle body 11, and an LF communication area described later. And an LF antenna 15 provided in front of the vehicle body 11 so that R is set.

The sensor units 13A to 13D are fixed inside the tires (for example, wheels) of the wheels 12A to 12D, respectively, and rotate integrally with the wheels 12A to 12D.

The control device 14 receives sensor signals from the sensor units 13A to 13D in a predetermined cycle, and detects the state (whether there is an abnormality, etc.) of the wheels 12A to 12D to which the sensor units 13A to 13D are attached based on the received sensor signals. To do. Here, the sensor signal is a signal for notifying the tire condition of the wheels 12A to 12D to which the sensor units 13A to 13D are attached, and includes sensor identification information for identifying the sensor units 13A to 13D. For example, a UHF signal of 433.92 MHz and 9.6 kbps is used as the sensor signal. The sensor signal is a signal that can be distinguished from an LF (Low Frequency) signal used for a request signal described later, such as an RF signal, and a signal with a different specification can be used as long as communication quality can be ensured. Good.

The LF antenna 15 is disposed relatively close to one of the front wheel group and the rear wheel group. Here, the front wheel group is a wheel group to which the

front wheels

12A and 12B belong, and the rear wheel group is a wheel group to which the

rear wheels

12C and 12D belong. In the present embodiment, the LF antenna 15 is disposed on the front bumper of the vehicle body 11. The LF antenna 15 receives a request from the control device 14 and transmits a response request signal for requesting a response from the sensor unit. Here, the response request signal is a signal that requests the sensor units 13A to 13D to transmit a sensor signal, and for example, an LF signal of 125 kHz and 3.9 Kbps is used.

The range in which the sensor unit can detect the response request signal transmitted from the LF antenna 15 is the LF communication area R. The size of the LF communication area R is determined by the relationship between the signal strength of the response request signal that is an LF signal and the reception sensitivity of the sensor unit. In the present embodiment, as shown in FIG. 1, the

sensor units

13A and 13B attached to the

front wheels

12A and 12B are included in the LF communication area R, while the

sensor units

13C and 13D attached to the

rear wheels

12C and 12D are The arrangement position of the LF antenna 15 is determined so as not to be included in the LF communication area R. Therefore, the

sensor units

13A and 13B of the front wheel group included in the LF communication area R respond to (synchronize) the response request signal and return the sensor signal, but the rear wheel group of the rear wheel group not included in the LF communication area R. The

sensor units

13C and 13D do not respond (synchronize) with the response request signal.

The installation position of the LF antenna 15 is set so that the

sensor units

13C and 13D of the rear wheel group are included in the LF communication area R and the

sensor units

13A and 13B of the front wheel group are not included in the LF communication area R. Then, the

sensor units

13C and 13D in the rear wheel group send back notification signals in synchronization with the response request signal, but the

sensor units

13A and 13B in the front wheel group do not respond to the response request signal. When such an LF communication area R is set, the LF antenna 15 is disposed behind the vehicle body 11. Hereinafter, as illustrated in FIG. 1, an example in which the LF antenna 15 is disposed in front of the vehicle body 11 will be described.

FIG. 2 is a functional configuration diagram of the tire condition detection device of the present embodiment. Hereinafter, when the wheels 12A to 12D and the sensor units 13A to 13D are not distinguished, they are collectively referred to as the wheels 12 and the sensor unit 13. In the following, it is assumed that a UHF signal is used as a sensor signal and an LF signal is used as a response request signal.

As shown in FIG. 2, the sensor unit 13 attached to each wheel 12 includes a reception unit 132 that receives an LF signal as a response request signal via the reception antenna 131, and a UHF as a sensor signal via the transmission antenna 133. The transmission unit 134 that transmits a signal, the tire state acquisition unit 135 that acquires the tire state such as air pressure and temperature, the rotation direction acquisition unit 136 that acquires the rotation direction of the wheel 12, and the sensor unit 13 are individually assigned. And a storage unit 137 for storing the unit identifier.

The tire state acquisition unit 135 acquires tire state information indicating the tire state such as air pressure and temperature, and outputs the acquired tire state information to the transmission unit 134. The tire state acquisition unit 135 may be configured by an air pressure sensor or a temperature sensor, or may be an interface connected thereto.

The rotation direction acquisition unit 136 is arranged so that the rotation direction information indicating the rotation direction of the left and right wheels 12 is different from each other on the front wheel and the rear wheel to which the sensor unit 13 is attached, and the acquired rotation direction information is transmitted to the transmission unit 134. Output to. The rotation direction acquisition unit 136 may be configured from a sensor that detects the rotation direction of the wheel 12, or may be an interface connected to the sensor. The rotation direction of the wheel 12 is determined based on the phase difference between the outputs of the two acceleration sensors provided on the wheel 12.

Specifically, as shown in FIG. 3, the wheel 12 includes an acceleration sensor X (not shown) having a detection direction A1 perpendicular to the tangential direction of the wheel 12 and detection parallel to the tangential direction of the wheel 12. An acceleration sensor Y (not shown) having a direction A2 is provided at a predetermined position A of the wheel 12. When the two acceleration sensors rotate left together with the wheel 12, that is, when the acceleration sensors X and Y rotate along the route A → B → C → D, the output of the acceleration sensor X at the predetermined position A is the centrifugal force of the wheel rotation. The output is increased as the wheel 12 rotates to B, and the output increases at the position C. The output is maximized because it receives the influence of gravity according to the centrifugal force of the wheel rotation. As a result, the output decreases. On the other hand, the output of the acceleration sensor Y increases as it rotates from A to B, reaches a maximum at B, then decreases as it rotates to C, and reaches a minimum at D. Therefore, when the outputs of the acceleration sensor X and the acceleration sensor Y are compared, the phase of the sensor Y is 90 degrees earlier than the sensor X, and the phase difference is −90 degrees. Conversely, when the acceleration sensor rotates right together with the wheel 12, the phase of the sensor X is 90 degrees earlier than the sensor Y, and the phase difference is +90 degrees. Thus, the rotation direction of the wheel 12 is determined by the positive / negative of the phase difference.

As shown in FIG. 2, the transmission unit 134 transmits a UHF signal via the transmission antenna 133. Specifically, the transmission unit 134 includes UHF including sensor identification information stored in the storage unit 137, tire state information acquired by the tire state acquisition unit 135, and rotation direction information acquired by the rotation direction acquisition unit 136. Generate and send a signal. As shown in FIG. 4A, when receiving the LF signal (response request signal) from the LF antenna 15, the transmission unit 134 transmits a UHF signal in a cycle C2 in synchronization with the LF signal. As shown in FIG. 4B, when the LF signal is not received, the transmission unit 134 transmits the UHF signal in a predetermined cycle C1 asynchronously with the LF signal from the LF antenna 15. In FIG. 4, the transmitter 134 of the

sensor units

13B and 13D is not shown for convenience of explanation.

The control device 14 provided in the vehicle body 11 includes a transmission unit 141 that transmits an LF signal via the LF antenna 15, a reception unit 143 that receives a UHF signal via the reception antenna 142, and a sensor unit that transmits the UHF signal. 13 includes a wheel determination unit 144 that specifies the position of the wheel 12 to which the wheel 13 is attached, and a storage unit 145 that stores the position specified by the wheel determination unit 144 in association with the unit identifier.

The transmission unit 141 transmits an LF signal via the LF antenna 15. Specifically, as illustrated in FIG. 4, the transmission unit 141 transmits the LF signal asynchronously with a predetermined period C1 at which the reception unit 143 receives the UHF signal. Moreover, the transmission part 141 transmits an LF signal with the period C2 shorter than the predetermined period C1 by which a UHF signal is received.

Further, the transmission unit 141 transmits an LF signal with transmission power that maintains a predetermined signal strength in a predetermined LF communication area. Here, as described above, the predetermined LF communication area is set so as to include a wheel group on the side closer to the LF antenna 15 and not include a wheel group on the far side. In the present embodiment shown in FIG. 1, transmission section 141 transmits an LF signal with transmission power that maintains a predetermined signal strength in LF communication area R that includes a front wheel group and does not include a rear wheel group.

The wheel determination unit 144 determines the wheel of the wheel 12 according to whether the UHF signal received by the reception unit 143 is synchronized with the LF signal transmitted from the LF antenna 15. Here, the wheel determination of the wheel 12 refers to specifying the position of the wheel 12 to which the sensor unit 13 that has transmitted the UHF signal received by the receiving unit 143 is attached.

Specifically, when the UHF signal received by the reception unit 143 is synchronized with the LF signal transmitted from the LF antenna 15, the wheel determination unit 144 determines that the sensor unit (wheel) that has transmitted the UHF signal is It is determined that the wheel group is close to the LF antenna 15. For example, when the LF communication area R shown in FIG. 1 is set, if the UHF signal received by the receiving unit 143 is synchronized with the LF signal transmitted via the LF antenna 15, It is determined that the UHF signal is from the

wheels

12A and 12B (

sensor units

13A and 13B) belonging to the group. Further, the wheel determination unit 144 determines which one of the left and

right wheels

12A and 12B of the front wheel group is the UHF signal based on the rotation direction information included in the UHF signal. As shown in FIG. 5, if the correspondence between the sensor unit 13 and the wheel 12 is confirmed, the wheel determination unit 144 includes the determined wheel identification information (here, 12A and 12B) and the UHF signal. Sensor identification information (in this case, 13A, 13B) is stored in the storage unit 145 in association with each other.

Further, when the UHF signal received by the receiving unit 143 is asynchronous with the LF signal transmitted from the LF antenna 15, the wheel determining unit 144 determines whether the sensor identification information included in the UHF signal has been determined. Determine whether or not. The wheel determination unit 144 determines that the wheel group is far from the LF antenna 15 when the wheel has not been determined. For example, when the LF communication area R shown in FIG. 1 is set, the wheel determination unit 144, when the sensor identification information included in the received UHF signal is not wheel determination,

wheels

12C and 12D (sensors belonging to the rear wheel group) It is determined that the signal is a UHF signal from the

units

13C and 13D). In addition, the wheel determination unit 144 determines one of the left and

right wheels

12C and 12D of the rear wheel group based on the rotation direction information included in the UHF signal. As shown in FIG. 5, the wheel determination unit 144 associates the determined wheel identification information (here, 12C, 12D) with the sensor identification information (here, 13C, 13D) included in the UHF signal. The data is stored in the storage unit 145.

Next, the operation of the tire condition monitoring apparatus configured as described above will be described.
As shown in FIG. 4, the sensor unit 13A (13B) (front wheel group), the sensor unit 13C (13D) (rear wheel group) transmit UHF signals at a predetermined cycle C1, and the predetermined period until the LF antenna 15 determines the wheel. Over a period, the LF signal is transmitted in a cycle C2 that is sufficiently shorter than the UHF signal transmission cycle C1. The front wheel group sensor unit 13A (13B) existing in the LF communication area R transmits a UHF signal having a predetermined period C2 in synchronization with the received LF signal. On the other hand, the sensor unit 13C (13D) in the rear wheel group outside the LF communication area R does not respond because it cannot receive the LF signal, and therefore does not transmit the UHF signal of the cycle C2 synchronized with the LF signal and transmits the UHF signal of the cycle C1. Keep sending.

The receiving unit 143 of the control device 14 receives a UHF signal having a predetermined period C1 from the sensor unit 13A (13B) of the front wheel group and the sensor unit 13C (13D) of the rear wheel group, and transmits an LF signal from the antenna 15. Then, the UHF signal having the period C2 synchronized with the LF signal is received only from the sensor unit 13A (13B) of the front wheel group. The wheel determination unit 144 of the control device 14 executes the following wheel determination process from the UHF signal received at the cycle C1 and the UHF signal received at the cycle C2.

FIG. 6 is a flowchart showing the wheel determination operation in the present embodiment. The transmission unit 141 of the control device 14 transmits an LF signal that can be detected within the LF communication area R as a response request signal via the LF antenna 15 (step S101).

The wheel determination unit 144 of the control device 14 determines whether or not a UHF signal as a sensor signal has been received from the sensor unit 13 (step S102). When no UHF signal is received from the sensor unit 13 (step S102; No), the process returns to step S101.

On the other hand, when the receiving unit 143 receives a UHF signal from the sensor unit 13 (step S102; Yes), the wheel determination unit 144 determines whether the UHF signal is synchronized with the LF signal transmitted in step S101. Is determined (step S103).

When the UHF signal received by the reception unit 143 is activated by the LF signal transmitted in step S101 and transmitted (step S103; Yes), the wheel determination unit 144 includes a wheel group in the LF communication area R ( The wheel determination process of the front wheel group close to the LF antenna 15 is performed. That is, it is determined whether the UHF signal is transmitted from the

sensor unit

13A or 13B provided on any of the left and

right wheels

12A and 12B constituting the front wheel group. For this reason, the wheel determination unit 144 extracts the rotation direction information included in the UHF signal received by the reception unit 143, and determines which of the front wheel group is the left or right wheel 12 based on the rotation direction information. (Steps S104 to S107). As described above, the rotation direction information is information indicating the rotation direction of the wheel 12 detected by a rotation direction sensor provided on the wheel 12. Here, when the vehicle body 11 is moving forward, the

wheels

12B and 12D attached to the right side of the traveling direction of the vehicle body 11 are recognized as rotating right and attached to the left side of the traveling direction of the vehicle body 11. The observation reference positions are determined so that the

wheels

12A and 12C are recognized as rotating left. For example, when the observation reference position is set at the axial center of the axle to which the left and right wheels are attached, and the vehicle body 11 is moving forward, the

wheels

12B and 12D attached on the right side from the observation reference position are moved in the axle direction. If it looks facing, it will look counterclockwise, and if it sees the

wheel

12A, 12C attached to the left side facing an axle direction, it will look clockwise. That is, it is recognized that the wheel 12 rotating forward in the same direction is rotating in different directions on the left and right. Since the rotation direction of the wheel 12 varies depending on the observation reference position, the position where the rotation direction is observed is defined as the observation reference position.

Specifically, when the rotation direction of the wheel 12 indicated by the rotation direction information is right rotation (step S104; Yes), the wheel determination unit 144 determines that the wheel determination unit 144 has the right wheel in the determined wheel group. It determines with it being the wheel 12, and determines the wheel position of the said UHF signal transmission origin. In the example illustrated in FIG. 1, the wheel determination unit 144 determines that the UHF signal transmission source wheel is the right front wheel 12B from the rotation direction information (right rotation) included in the UHF signal (step S105).

When the rotation direction of the wheel 12 is not right rotation (step S104; No), the wheel determination unit 144 determines whether or not the rotation direction of the wheel 12 is left rotation (step S106). When the rotation direction of the wheel 12 is the left rotation (step S106; Yes), the wheel determination unit 144 determines that the wheel of the UHF signal transmission source is the left front wheel 12A (step S107). When the rotation direction of the wheel 12 is not left-turning (step S106; No), the process returns to step S101.

On the other hand, when it is determined that the UHF signal received by the reception unit 143 is not synchronized with the LF signal transmitted from the LF antenna 15 (step S103; No), the wheel determination unit 144 transmits the UHF signal to the sensor unit. The wheel 12 to which 13 is attached is determined to be the wheel group outside the LF communication area R, that is, the left rear wheel 12C or the right rear wheel 12D included in the rear wheel group. In such a case, the wheel determination unit 144 determines whether the sensor unit 13 that has transmitted the UHF signal is attached to the left rear wheel 12C or the right rear wheel 12D based on the rotation direction information included in the received UHF signal. Determine.

Based on the rotation direction information included in the received UHF signal, the wheel determination unit 144 determines whether or not the rotation direction of the wheel 12 to which the sensor unit 13 that has transmitted the UHF signal is attached is a right rotation ( Step S108).

When the rotation direction of the wheel 12 is right rotation (step S108; Yes), the wheel determination unit 144 determines that the UHF signal is transmitted from the sensor unit 13D attached to the right rear wheel 12D (step S109).

When the rotation direction of the wheel 12 is not right rotation (step S108; No), the wheel determination unit 144 determines whether or not the rotation direction of the wheel 12 is left rotation (step S110). When the rotation direction of the wheel 12 is counterclockwise (step S110; Yes), the wheel determination unit 144 determines that the UHF signal is transmitted from the sensor unit 13C attached to the left rear wheel 12C (step S111). When the rotation direction of the wheel 12 is not left rotation (step S110; No), the process returns to step S101.

As described above, the wheel determination unit 144 determines whether the sensor unit 13 that transmitted the UHF signal is attached to the left front wheel 12A, the right front wheel 12B, the left rear wheel 12C, or the right rear wheel 12D. Determine. When determining the wheel 12 to which the sensor unit 13 is attached, the wheel determination unit 144 determines whether the received UHF signal includes identification information of the sensor unit 13 (steps S112 to S115).

When the received UHF signal includes the identification information of the sensor unit 13 (steps S112 to S115; Yes), the wheel determination unit 144 stores the determined position of the wheel 12 and the identification information of the sensor unit 13 in association with each other. The data is stored in the unit 145 (step S116). In addition, the wheel determination unit 144 outputs the determined position of the wheel 12 and the identification information of the sensor unit 13 to a vehicle-mounted device (not shown) via a communication unit (not shown) (step S117).

According to the tire condition monitoring apparatus according to the present embodiment, the LF antenna 15 is disposed on the front bumper of the vehicle body 11, only the front wheel group is set to enter the LF communication area R, and the UHF signal synchronized with the LF signal is transmitted to the front wheel. Since it is determined as a signal from the

sensor units

13A and 13B provided on the wheels 12 of the group, and the UHF signal that is asynchronous with the LF signal and the wheels excluding the wheels 12 of the front wheel group are determined as the rear wheel group, The number of antennas can be reduced to one, so that the cost can be reduced and the flexibility of the layout of the vehicle body can be improved.

In addition, the conventional method of determining the wheel using the RSSI value of the UHF signal may reduce the wheel determination accuracy due to factors such as a positional shift of the LF antenna and a change in radio wave intensity. According to the tire condition monitoring apparatus, the wheel group is determined synchronously / asynchronously with the LF signal, and the left and right are determined based on the wheel rotation direction. The accuracy of determination can be improved.

Note that the present invention is not limited to the above embodiment, and can be implemented with various modifications. For example, in the above-described embodiment, the biaxial acceleration sensor is used as the rotation direction sensor, but the rotation direction information may be acquired by a magnetic sensor or an optical sensor instead of the acceleration sensor. In addition, the arrangement, size, and the like of each component in the above embodiment can be changed as appropriate. In addition, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

This application is based on Japanese Patent Application No. 2012-049224 filed on March 6, 2012. All this content is included here.

Claims

A plurality of sensor units respectively provided on front wheels and rear wheels constituting a vehicle wheel, a vehicle body side antenna that transmits a response request signal for requesting a response to the sensor unit, and wireless communication with each sensor unit A vehicle body side device,
In the vehicle body side antenna, a front wheel or a rear wheel closer to the vehicle body side antenna receives the response request signal, and a front wheel or rear wheel far from the vehicle body side antenna receives the response request signal. Arrange to avoid receiving,
Each sensor unit transmits a sensor signal including sensor identification information to the vehicle body side device asynchronously with the response request signal transmitted by the vehicle body antenna, and receives the response request signal. A sensor signal including sensor identification information is transmitted in synchronization with the response request signal,
Each sensor unit is configured and arranged so that rotation direction information indicating rotation directions of the left and right wheels of the front wheel and the rear wheel is different from each other, and detects the rotation direction of the wheel, and detects the detected wheel. A sensor signal including rotation direction information indicating the rotation direction and sensor identification information is transmitted to the vehicle body side device;
The vehicle body side device determines a wheel closer to the vehicle body side antenna from the sensor identification information included in the sensor signal received in synchronization with the response request signal, and the sensor signal received asynchronously with the response request signal Determining the wheels on the side far from the vehicle body side antenna from the sensor identification information included in, and determining the left and right wheels from the rotation direction information included in the sensor signal,
The tire condition monitoring apparatus characterized by the above-mentioned.
Each sensor unit transmits a sensor signal asynchronously with the response request signal in a first cycle, and the vehicle body side antenna requests a response in a second cycle shorter than the first cycle until the wheel is determined. 2. The tire condition monitoring apparatus according to claim 1, wherein a signal is transmitted.
The tire state monitoring device according to claim 1 or 2, wherein the vehicle body side antenna is installed in a front portion of a vehicle.