JP2006306184A - Wheel side antenna device, and tire condition detecting device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel side antenna device capable to communicate in a wide range even if it is mounted in a space-limited place, and a tire condition detecting device having the antenna device. <P>SOLUTION: This wheel side antenna device is installed to wheels 6a-6d, for communicating with a vehicle body 7 side. A plurality of antennas 24 constituted by winding a conducting wire 24b around a magnetic core 24a are provided, and a plurality of antennas 24 are connected in parallel. Thereby, unless the length of the magnetic core 24a is made large, a range capable to communicate with the vehicle body 7 side can be made wider than when a single antenna is provided. Also, when a plurality of antennas 24 are provided, the length of one antenna 24 can be made short, so that the device can be mounted in a narrow place. Thus, if the antenna 24 is mounted to the space-limited place, a wide range of communication is possible. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wheel side antenna device for communicating with a vehicle body side and a tire condition detecting device using the wheel side antenna device.

  Conventionally, in a tire condition detection device, a transmitter equipped with a sensing unit such as a pressure sensor and an antenna for communicating with a vehicle body side is attached to a wheel side to which a tire is attached, and a detection signal from the sensor is indicated. Transmitting radio waves to the car body. (For example, refer to Patent Document 1).

When the antenna mounted on the wheel side is configured by winding a conductive wire around the magnetic core, the antenna gain increases as the length of the magnetic core increases with respect to the cross-sectional area of the magnetic core. Thus, the range in which communication with the vehicle body side is possible is widened.
Japanese Patent No. 3212311

  However, since such an antenna is disposed in a wheel such as in an air injection valve, there is a limitation on a mounting location. As a result, the length of the magnetic core is also limited by the size of the space in which the antenna is mounted, so that there is a problem that the range in which communication with the antenna on the vehicle body side is possible is limited to a narrow range.

  An object of this invention is to provide the wheel side antenna apparatus which can be communicated in a wide range even if it mounts in the place where the space was restricted, and a tire condition detection apparatus which has it.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a wheel side antenna device provided on the wheels (6a to 6d) for communicating with the vehicle body (7) side, wherein the magnetic core (24a ) Is provided with a plurality of antennas (24) formed by winding a conductive wire (24b), and the plurality of antennas (24) are connected in parallel.

  In this way, by connecting a plurality of antennas (24) in parallel, communication with the vehicle body (7) side can be achieved compared to the case of providing a single antenna without increasing the length of the magnetic core (24a). The possible range can be widened. Moreover, since the length per antenna (24) can be shortened by using a plurality of antennas (24), it can be mounted in a narrow place. Therefore, even if the antenna (24) is mounted in a place where space is limited, it is possible to communicate over a wide range.

  Further, as in the invention described in claim 2, by providing the plurality of antennas (24) at positions where the distance between the plurality of antennas (24) is maximized, the radio waves of each of the plurality of antennas (24) are provided. Can interfere with each other and reduce the antenna gain.

  Further, as in the invention described in claim 3, a detection signal corresponding to the air pressure of the tire provided on each of the plurality of wheels (6a to 6d) and provided to each of the plurality of wheels (6a to 6d) is provided. The sensing unit (21) for output, the control unit (23a) for signal processing the detection signal of the sensing unit (21), and the detection signal signal-processed by the control unit (23a) are transmitted to the vehicle body (7) side. A plurality of antennas (24) may be mounted on a sensor device (2) having a transmitting unit.

  Further, when the sensor device (2) is provided inside the air injection valve (8) for injecting air into the tire as in the invention described in claim 4, the space is limited, so that the effect is particularly effective. Demonstrate.

  Further, as in the invention described in claim 5, the transmission / reception unit (23b) is configured to receive a radio wave for power charging from the vehicle body (7) side, and the sensor device (2) You may have the charge part (22) which performs electric power charge by the electromagnetic wave for charge.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The wheel side antenna device of the present embodiment is used as a wheel side antenna of the tire condition detecting device.

  FIG. 1 is a block diagram showing the overall configuration of a tire condition detection device according to an embodiment of the present invention. The upper direction in the drawing of FIG. 1 corresponds to the front of the vehicle 1 and the lower direction of the drawing corresponds to the rear of the vehicle 1. With reference to this figure, the tire condition detection apparatus in this embodiment is demonstrated.

  As shown in FIG. 1, the tire condition detection device is attached to a vehicle 1 and includes a sensor device 2, a transceiver 3, a control device 4, and an alarm device 5.

  As shown in FIG. 1, the sensor device 2 is attached to each wheel 6 a to 6 d in the vehicle 1, detects the air pressure of the tire attached to the wheels 6 a to 6 d, and detects a detection signal indicating the detection result. Data is stored in a transmission frame and transmitted. The transmitter / receiver 3 is attached to the vehicle body 7 side of the vehicle 1, and charges the power to the sensor device 2 and receives a transmission frame transmitted from the sensor device 2. The control device 4 obtains the tire pressure by performing various processes and calculations based on the detection signal stored in the transmission frame received via the transceiver 3.

  FIG. 2 shows a block configuration of the sensor device 2. The sensor device 2 is driven by the electric wave transmitted from the transmitter / receiver 3 for electric power charging, and is driven based on the charged electric power.

  As shown in FIG. 2, the sensor device 2 has a configuration including a sensing unit 21, a charging unit 22, a microcomputer 23, and an antenna 24, and transmits radio waves for power charging from the transceiver 3 through the antenna 24. It operates by receiving and converting the radio wave into electric power energy and storing it in the charging unit 22. The power charging by the transponder method is well known in the field of battery-less ID tag recognition and the like, and will not be described here.

  The sensing unit 21 includes, for example, a diaphragm type pressure sensor and a temperature sensor, and outputs a detection signal corresponding to the tire pressure and a detection signal corresponding to the temperature. The charging unit 22 charges the radio wave received from the antenna 24 and supplies power to the sensing unit 21 and the microcomputer 23.

  The microcomputer 23 includes a CPU, a ROM, a RAM, an I / O, and the like. The microcomputer 23 includes a control unit 23a, a transmission / reception unit 23b, and the like, and executes predetermined processing according to a program stored in the ROM. It has become.

  The control unit 23a receives the detection signal from the sensing unit 21, performs signal processing on the signal as necessary, and uses this as data indicating the detection result as the sensor device 2 attached to any of the wheels 6a to 6d. It is stored in the transmission frame together with the ID information indicating that. Thereafter, the control unit 23a transmits the transmission frame to the transceiver 3 through the transmission / reception unit 23b. The process of sending a transmission frame to the transceiver 3 is executed according to the program when a radio wave transmission for performing the power charging is turned off. For example, the control unit 23a monitors ON / OFF of radio wave transmission from the transceiver 3, and executes a process of sending a transmission frame based on a falling signal when the radio wave transmission is turned off.

  The transmission / reception unit 23b functions as an input unit that receives a radio wave for power charging through the antenna 24 and sends it to the charging unit 22 and the control unit 23a, and transmits a transmission frame sent from the control unit 23a to the transceiver 3. It functions as an output unit for transmission.

  3A is a cross-sectional view of the air injection valve 8 incorporating the sensor device 2 as viewed from the front, and FIG. 3B is a cross-sectional view taken along line AA of FIG. As shown in FIGS. 3A and 3B, the sensor device 2 is integrally formed with the air injection valve 8 (70 × 30 × 10 mm) by a resin mold or the like. The antenna 24 is a solenoid-type magnetic field antenna, and is configured by winding a conductive coil 24b around a ferrite core 24a. Two antennas 24 are mounted on the substrate of the sensor device 2 so as to be parallel to each other. The two antennas 24 are electrically connected in parallel, and are provided at positions where the distance between the two antennas 24 in the air injection valve 8 is maximum (in this embodiment, both ends of the substrate).

  The air injection valve 8 is attached to the tire wheel such that the sensor device 2 is located inside the tire wheel and the air injection port is located outside the tire wheel. Thus, the corresponding tire air pressure is detected, and the transmission frame is transmitted at a predetermined transmission timing every predetermined cycle (for example, every minute) through the antenna 24 provided in each sensor device 2.

  Returning to FIG. 1, the transmitter / receiver 3 outputs a power charging radio wave at a predetermined communication timing every predetermined cycle (for example, every minute) to charge the power of the sensor device 2. After completion, the electric wave for power charging is turned on and off at a predetermined timing synchronized with the rotation of the wheels 6a to 6d. And the transmission frame sent from the sensor apparatus 2 at that time is received.

  FIG. 4 is a block diagram showing the configuration of the transceiver 3. As shown in FIG. 4, the transceiver 3 includes a transceiver 31 and a transceiver antenna 32. The transmission / reception unit 31 inputs a function as an output unit that outputs a radio wave for power charging to the sensor device 2 through the antenna 32 and the received transmission frame from each sensor device 2 and receives the transmission frame. Thus, it functions as an input unit to be sent to the control device 4. As described above, the transmitter / receiver 3 according to the present embodiment has a configuration that serves as both a transmission unit that transmits a radio wave for power charging and a reception unit that receives a transmission frame. However, these may be configured separately. It is. The antenna 32 is used for both transmission and reception, but is hereinafter referred to as a “transmission antenna”.

  5 and 6 show the positional relationship between the sensor device 2 and the transceiver 3, FIG. 5 is a view as seen from the vehicle traveling direction, and FIG. 6 is a side view. Each transceiver 3 is installed at a location corresponding to the position of each sensor device 2 in the vehicle body 7. For example, as shown in FIGS. 5 and 6, the vehicle body 7 is located at a predetermined distance from each sensor device 2. It is fixed to.

  Returning to FIG. 1, the control device 4 is a known device including a CPU, a ROM, a RAM, an I / O, a counter, and the like, and executes a predetermined process in accordance with a program stored in the ROM. .

  The control device 4 receives vehicle speed data obtained by another ECU (for example, a meter ECU) through an in-vehicle LAN (CAN) or the like, detects the rotational state of each wheel 6a to 6d based on the vehicle speed data, A radio wave for power charging is output to each sensor device 2 according to the detected rotation state. Further, the control device 4 receives the transmission frame sent from the transceiver 3, and based on the ID information indicating the wheel to which each sensor device 2 is stored, the transmission frame sent is the wheel 6a. -6d is specified.

  Further, the control device 4 obtains the tire pressure of each of the wheels 6a to 6d by performing various signal processing and calculation based on the data indicating the detection result stored in the received transmission frame, and the obtained tire pressure. An electrical signal corresponding to the above is output to the alarm device 5. Specifically, the control device 4 determines whether or not the tire air pressure is below a predetermined threshold value, and outputs a signal indicating that the tire air pressure has decreased to the alarm device 5 based on the determination result. It has become.

  The alarm device 5 is disposed at a place where the driver can visually recognize, and is configured by, for example, an alarm lamp, an alarm indicator (display), or an alarm buzzer installed in an instrument panel in the vehicle 1. For example, when a signal indicating a decrease in tire air pressure is sent from the control device 4, the alarm device 5 notifies the driver of the decrease in tire air pressure by issuing an alarm indicating that fact. The tire condition detection device is configured as described above.

  Next, in the antenna 24 of the sensor device 2, the superiority of the antenna 24 of the present embodiment is shown in comparison with several types of antennas having the same mass and different shapes.

  FIG. 7 shows the external appearance of the antennas A to E. The antennas A to E shown in FIG. 7 all have the same mass. An antenna E in FIG. 7 corresponds to the antenna 24 of the present embodiment.

  Subsequently, after these antennas A to E are built in the air injection valve 8, they are mounted on an actual vehicle and the communicable ranges are measured. FIG. 8 is a side view showing the positional relationship between the air injection valve 8 and the transceiver 3. As shown in FIG. 8, the transmitter / receiver 3 is provided with a determination lamp 33 that is turned on when a radio wave is received. Whether or not the transceiver 3 has received radio waves from the antennas A to E on the wheel 6 side can be determined by the determination lamp 33, so that the communicable range of the antennas A to E can be measured using this. it can.

  The result of having measured the communicable range of each antenna A to E in FIG. 9 is shown. As shown in FIG. 9, it can be seen that the communicable range becomes wider as the ferrite length of the antennas A to E becomes longer. In order to achieve a target communicable range (for example, 90 °) with a single antenna, the shape of the antenna B may be adopted. However, since the size of the air injection valve 8 is 70 × 30 × 10 mm, it is difficult to mount the antenna B having a ferrite length of 35 mm on the air injection valve 8. On the other hand, the antenna E of the present embodiment can realize a communicable range similar to that of the antenna B having a ferrite length of 35 mm, and further, since the ferrite length is 25 mm, it can be easily mounted on the air injection valve 8. become.

  As described above, by connecting the two antennas 24 in parallel, the communicable range with the vehicle body 7 side is wider than the case where a single antenna is provided without increasing the length of the magnetic core 24a. can do. Further, by using two antennas 24, the length of each antenna 24 can be shortened, so that it can be mounted in a narrow place. Therefore, even if the antenna 24 is mounted in a place where space is limited, it is possible to communicate over a wide range.

  Further, by providing the two antennas 24 at positions where the distance between the antennas 24 is maximized, it is possible to prevent the radio waves of the two antennas 24 from interfering with each other and lowering the antenna gain.

(Other embodiments)
In the above embodiment, the transponder system is used for wireless communication between the sensor device 2 on the wheel 6 side and the transceiver 3 on the vehicle body 7 side. However, a battery is provided on the wheel 6 side, and the sensor device 2 is operated by the battery. The wireless communication with the transmitter / receiver 3 on the vehicle body 7 side may be performed.

  Moreover, in the said embodiment, although the sensor apparatus 2 is built in the air injection valve 8, you may mount in any position not only in it but the wheel 6 side.

1 is a block diagram illustrating an overall configuration of a tire state detection device according to an embodiment of the present invention. 3 is a diagram showing a block configuration of a sensor device 2. FIG. (A) is sectional drawing which looked at the air injection valve 8 in which the sensor apparatus 2 was incorporated from the front, (b) is AA sectional drawing of (a). 2 is a block diagram showing a configuration of a transceiver 3. FIG. It is the figure seen from the vehicle advancing direction which shows the arrangement | positioning relationship between the sensor apparatus 2 and the transmitter / receiver 3. FIG. It is a side view which shows the arrangement | positioning relationship between the sensor apparatus 2 and the transmitter / receiver 3. FIG. It is explanatory drawing which shows the external appearance of antenna AE. 4 is a side view showing the arrangement relationship between the air injection valve 8 and the transceiver 3. FIG. It is a figure which shows the result of having measured the communicable range of antenna AE.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Sensor apparatus, 6a-6d ... Wheel, 7 ... Vehicle body, 8 ... Air injection valve, 21 ... Sensing part, 22 ... Charge part, 23a ... Control part, 23b ... Transmission / reception part, 24 ... Antenna, 24a ... Magnetic body core , 24b ... conducting wire.

Claims (5)

A wheel-side antenna device provided on the wheels (6a to 6d) for communicating with the vehicle body (7) side,
A plurality of antennas (24) configured by winding a conductive wire (24b) around a magnetic core (24a) are provided,
The plurality of antennas (24) are connected in parallel, and the wheel side antenna device is characterized. The wheel-side antenna device according to claim 1, wherein the plurality of antennas (24) are respectively provided at positions where a distance between the plurality of antennas (24) is maximized. A sensing unit (21) provided on each of the plurality of wheels (6a to 6d) and outputting a detection signal corresponding to the tire air pressure provided on each of the plurality of wheels (6a to 6d), and the sensing unit A control unit (23a) that performs signal processing on the detection signal of (21), and a transmission / reception unit (23b) that transmits the detection signal signal-processed by the control unit (23a) to the vehicle body (7) side. The tire condition detecting device according to claim 1 or 2, wherein the plurality of antennas (24) are mounted on a sensor device (2) having the same. The tire condition detection device according to claim 3, wherein the sensor device (2) is provided inside an air injection valve (8) for injecting air into the tire. The transceiver unit (23b) is configured to receive a radio wave for power charging from the vehicle body (7) side,
The tire condition detection device according to claim 3 or 4, wherein the sensor device (2) includes a charging unit (22) that performs power charging by the electric wave for power charging.

Images