JP2014231337A - Wheel position specification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel position specification device capable of correctly specifying a position of a wheel side unit which transmitted a signal even in a position specification method using reception intensity of a signal on a receiver.SOLUTION: An RF transmission circuit of a tire sensor unit 3 transmits RF signals from plural rotation angles including a reference angle on a wheel 2. On a receiver unit controller 33 of a receiver unit 4, position characteristic which is determined based on reception intensity difference in other rotation angle with respect to the reference angle is set for each position of the wheel 2. The receiver unit controller 33 specifies that from which wheel 2 comprising the tire sensor unit 3 the RF signal was transmitted based on the position characteristic.

Description

  The present invention relates to a wheel position specifying device for specifying the positions of a plurality of wheels provided in a vehicle, and more particularly to a wheel position specifying device suitable for use in a tire condition monitoring device.

  As a device for enabling a driver to check the state of a plurality of tires provided in a vehicle in a passenger compartment, a wireless tire state monitoring device has been proposed. In general, a tire condition monitoring device includes a plurality of transmitters (wheel side units) that are respectively mounted on wheels of a vehicle, and a receiver (receiver unit) that is mounted on a vehicle body of the vehicle. Each transmitter detects a corresponding tire state, that is, pressure and temperature in the tire, and wirelessly transmits a signal including data indicating the detected tire state through a transmission antenna.

  On the other hand, the receiver receives signals from the transmission antennas of the respective transmitters through the reception antennas, and displays information related to tire pressure on a display provided in the passenger compartment as necessary. Further, in the tire condition monitoring device, it is determined which of the plurality of tires the transmitted signal is transmitted from a transmitter, in other words, the position of the wheel related to the received signal. Are specified at the receiver.

  As a specifying method, there is a method of specifying the position of the transmitter in the receiver by comparing the reception intensity of the signal transmitted from each transmitter (see, for example, Patent Document 1). In Patent Document 1, when a transmitter provided on any of the wheels transmits a signal (radio wave), the signal is received by a plurality of receiving antennas in the receiver. At this time, since the level of the voltage induced in each reception antenna is different, the receiver specifies whether the wheel that transmitted the signal is the front wheel or the rear wheel based on the reception intensity at each reception antenna.

JP 2004-149093 A

  However, individual transmitters vary in their transmission outputs. Further, the receiver has directivity, and the reception intensity varies depending on the angle at which the signal transmitted from the transmitter is received. In addition, the amount of attenuation that occurs between the transmitter and the receiver due to a shield such as a vehicle body also varies. For this reason, there is a possibility that the position of the transmitter cannot be accurately specified only by the reception intensity due to various variations.

  An object of the present invention is to provide a wheel position specifying device capable of accurately specifying the position of a wheel side unit that has transmitted a signal, even if the position specifying method uses the reception intensity of a signal at a receiver. It is in.

  In order to solve the above problem, the wheel position specifying device according to claim 1 is a wheel position specifying device for specifying the positions of a plurality of wheels provided in a vehicle, and is provided in each of the wheels. A state detection unit that includes a wheel side unit and a receiver unit installed on the vehicle body of the vehicle, wherein the wheel side unit is set with unique identification information, and the wheel side unit detects the state of the wheel. And a transmission unit that wirelessly transmits a signal including the data detected by the state detection unit and the identification information, and the transmission unit receives the signal from a plurality of rotation angles including a reference angle in the wheel. The receiver unit includes a receiving unit for signals transmitted from each wheel side unit, and specifies which wheel side unit the signal is transmitted from. The wheel position specifying unit includes a wheel position specifying unit that receives signals at other rotation angles with respect to the received intensity at the reference angle with respect to the reception intensity of the signal at the receiving unit for all wheel side units. The gist is to set each position characteristic based on the magnitude relation of the intensity, and to specify which position the wheel-side unit transmits the signal based on the position characteristic.

  According to this, since the positions at which the wheel-side units are provided are all different from the receiving unit, the reception intensities at the receiving units of the signals transmitted from the respective angles of the wheel-side units are all different. And the positional characteristic was set for every wheel side unit, ie, every wheel, using the difference in the positional relationship with respect to a receiving part, and the difference in the angle which transmits a signal. Since this position characteristic is based on the magnitude of the reception intensity at other rotation angles with respect to the reference angle, the set position characteristic is relative, and it is affected by variations in the transmission output of the transmitter and the directivity of the receiver. Has universality. Therefore, since the wheel position is specified using the position characteristics set for each wheel, even the wheel position specifying operation using the received intensity can be accurately performed.

In the wheel position specifying device, the position characteristic is preferably set in the wheel position specifying unit when the wheel side unit is installed in the vehicle.
According to this, when the position specifying operation of the wheel side unit is performed while the vehicle is running, it is not necessary to set the directivity by the receiver unit, and the position specifying operation can be promptly performed.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is the position identification method using the received strength of the signal in a receiver, the position of the wheel side unit which transmitted the signal can be pinpointed correctly.

The schematic block diagram which shows the vehicle by which the tire condition monitoring apparatus of embodiment is mounted. The block diagram which shows the circuit structure of a tire sensor unit. The graph which shows the relationship between the position of an acceleration sensor, and acceleration. The figure which shows the receiving strength and receiving strength difference in each rotation angle in each wheel. The figure which shows the receiving strength and receiving strength difference in each rotation angle after wheel rotation.

  Hereinafter, an embodiment in which the wheel position specifying device is applied to a tire condition monitoring device will be described with reference to FIGS. As shown in FIG. 1, the traveling direction of the vehicle 1 is the front-rear direction of the vehicle 1, and the vehicle width direction of the vehicle 1 is the left-right direction of the vehicle 1.

  As shown in FIG. 1, the tire condition monitoring device includes four tire sensor units 3 as wheel-side units respectively attached to four wheels 2 of the vehicle 1, and a receiver unit 4 installed on the vehicle body of the vehicle 1. It has. Each wheel 2 includes a wheel portion 5 and a tire 6 attached to the wheel portion 5. Note that, hereinafter, the front left side is indicated by a reference symbol FL, the front right side is indicated by a reference symbol FR, the rear left side is indicated by a reference symbol RL, and the rear right side is indicated by a reference symbol RR.

  Each tire sensor unit 3 is attached to the wheel portion 5 to which the tire 6 is mounted so as to be disposed in the internal space of the tire 6. Each tire sensor unit 3 detects the state of the corresponding tire 6 (in-tire pressure, in-tire temperature) and the like, and includes a signal including data indicating the detected tire state, that is, a tire state data signal (hereinafter, data signal). Radio).

  As shown in FIG. 2, each tire sensor unit 3 includes a pressure sensor 11, a temperature sensor 12, an acceleration sensor 13, a sensor unit controller 14, and an RF transmission circuit 16 as a transmission unit. The tire sensor unit 3 is operated by a battery (not shown). The pressure sensor 11 as a state detection unit detects the pressure in the corresponding tire 6 (in-tire pressure), and outputs the in-tire pressure data obtained by the detection to the sensor unit controller 14. The temperature sensor 12 as a state detection unit detects the temperature in the corresponding tire 6 (in-tire temperature), and outputs tire temperature data obtained by the detection to the sensor unit controller 14.

  The acceleration sensor 13 is known as, for example, a piezoresistive type or a capacitance type acceleration sensor, and generates and outputs a data signal corresponding to the acceleration. As the acceleration sensor 13, an acceleration sensor capable of detecting an acceleration component in a direction along one detection axis is used, and gravitational acceleration is detected by the acceleration sensor 13. With the rotation of the wheel 2 when the vehicle 1 moves forward, the position, that is, the angle, of the tire sensor unit 3 in the rotation direction of the wheel 2 changes.

  As shown in FIG. 3, when the tire sensor unit 3 moves to the lowest position of the wheel 2, the acceleration sensor 13 detects an acceleration of + 1G when the detection sensor is attached in a state of extending in the vertical direction. Further, when the tire sensor unit 3 rotates 90 degrees from the lowest position of the wheel 2, the acceleration sensor 13 detects an acceleration of 0G. Furthermore, when the tire sensor unit 3 rotates 180 degrees from the lowest position of the wheel 2 and moves to the highest position of the wheel 2, the acceleration sensor 13 detects an acceleration of -1G. When the tire sensor unit 3 rotates 270 degrees from the lowest position of the wheel 2, the acceleration sensor 13 detects an acceleration of 0G. The acceleration sensor 13 outputs acceleration data obtained by the detection to the sensor unit controller 14.

  As shown in FIG. 2, the sensor unit controller 14 includes a CPU and a microcomputer including a storage unit 14 a (RAM, ROM, etc.), and the storage unit 14 a has an ID as identification information unique to each tire sensor unit 3. The code is registered. This ID code is information used to identify each tire sensor unit 3 in the receiver unit 4. As shown in FIG. 1, in the present embodiment, the ID code of the tire sensor unit 3 of the front left side FL is ID1, the ID code of the tire sensor unit 3 of the front right FR is ID2, and the tire sensor unit of the rear left RL 3 is ID3, and the ID code of the rear right RR is ID4.

  The sensor unit controller 14 outputs data including tire pressure data, tire temperature data, and acceleration data to the RF transmission circuit 16. The RF transmission circuit 16 modulates data from the sensor unit controller 14 to generate an RF signal, and wirelessly transmits the RF signal from the transmission antenna 18. The RF signal transmitted by the RF transmission circuit 16 has a frequency that can be used for wireless communication among electromagnetic waves and electrical signals, and is a high frequency in a range of approximately 300 Hz to 3 THz.

  For example, the sensor unit controller 14 of each tire sensor unit 3 periodically performs a tire state measurement operation at a first predetermined time interval, while performing an RF signal transmission operation more than the first predetermined time interval. Periodically at long second predetermined time intervals. However, when the measured tire condition shows an abnormality (for example, abnormal decrease in tire internal pressure, sudden change in tire internal pressure, sudden change in tire internal temperature, etc.), the tire sensor unit 3 has no relation to periodic transmission operation. Immediately perform the transmission operation.

Further, the sensor unit controller 14 performs an RF signal transmission operation at an interval different from the first and second predetermined time intervals during the position specifying operation of the wheel 2.
As shown in FIG. 1, the receiver unit 4 includes a receiver unit controller 33 and an RF receiver circuit 35 as a receiver. A display unit 38 is wired to the receiver unit controller 33 of the receiver unit 4. The receiver unit controller 33 is composed of a microcomputer including a CPU and a storage unit (ROM, RAM, etc.), and comprehensively controls the operation of the receiver unit 4. The RF receiving circuit 35 demodulates the RF signal received from each tire sensor unit 3 through the RF receiving antenna 32 and sends it to the receiver unit controller 33. Based on the RF signal from the RF receiving circuit 35, the receiver unit controller 33 grasps the tire pressure and the tire temperature of the tire 6 corresponding to the tire sensor unit 3 that is the transmission source.

  Furthermore, the receiver unit controller 33 determines which wheel 2 on the front, rear, left and right of the vehicle 1 is provided with the tire sensor unit 3 as a transmission source based on the RF signal from the RF receiving circuit 35. . Therefore, in this embodiment, the receiver unit controller 33 corresponds to a wheel position specifying unit.

  The receiver unit controller 33 causes the display 38 to display information on the tire pressure and the tire temperature. The indicator 38 is disposed in the visible range of the passenger of the vehicle 1 such as the passenger compartment, and the receiver unit controller 33 displays (informs) an abnormality in the tire pressure or the tire temperature on the indicator 38.

Next, a configuration for specifying the wheel position will be described.
The reception intensity at the RF receiving antenna 32 differs for each tire sensor unit 3 for each angle (rotation angle) of the wheel 2 and for each position of the wheel 2 where the tire sensor unit 3 is installed. Here, when the tire sensor unit 3 is positioned at the lowermost position of the wheel 2 as a reference angle (0 degree), the magnitude relationship of the received intensity at other angles is represented by each rotation with respect to the received intensity at the reference angle. This is expressed as the difference in received intensity at an angle.

  As shown in the table of FIG. 4, in each tire sensor unit 3, when rotated by 90 degrees (B in the graph), rotated by 180 degrees (C in the graph), and rotated by 270 degrees (graph) with respect to the reference angle. The difference in received intensity is calculated in advance by experiment or the like and registered in the receiver unit controller 33. For example, for the tire sensor unit 3 on the front left side FL, the received intensity difference is −3 dB when rotated 90 degrees, −2 dB when rotated 180 degrees, and +2 dB when rotated 270 degrees.

  As shown in the graph of FIG. 4, different characteristics are obtained for each position of the four wheels 2, and this characteristic is used as the position characteristic. This position characteristic is registered in the receiver unit controller 33 when the tire sensor unit 3 is first installed in the vehicle 1.

Next, the position specifying operation of the tire sensor unit 3 in the tire condition monitoring apparatus will be described with reference to FIGS. 4 and 5 together with the operation.
Now, during the position specifying operation while the vehicle 1 is traveling, in one tire sensor unit 3, every time four rotation angles (0 degree, 90 degrees, 180 degrees, 270 degrees) are detected by the acceleration sensor 13. The sensor unit controller 14 causes the RF transmission circuit 16 to transmit an RF signal. The RF signal includes tire pressure data, tire temperature data, ID code data, and acceleration data.

  When the receiver unit controller 33 receives the RF signal through the RF receiving antenna 32, the receiver unit controller 33 stores the received intensity difference at other rotation angles with respect to the reference angle (0 degree). And the receiver unit controller 33 acquires the positional characteristic of the wheel 2 (tire sensor unit 3) which transmitted RF signal based on the received intensity difference in each rotation angle. Thereafter, the receiver unit controller 33 compares the acquired position characteristics with the position characteristics of all wheels 2 registered in advance, and transmits the positions of the wheels 2 having the matching position characteristics, that is, RF signals. The position of the tire sensor unit 3 is specified.

Next, the operation after the wheel rotation will be described.
As shown in FIG. 5, the wheel 2 on the front left side FL moves to the rear left side RL together with the tire sensor unit 3 (ID1), and the wheel 2 on the front right side FR moves to the rear right side RR together with the tire sensor unit 3 (ID2). Suppose you move. Further, it is assumed that the wheel 2 on the rear left side RL moves to the front right side FR together with the tire sensor unit 3 (ID3), and the wheel 2 on the rear right side RR moves to the front left side FL along with the tire sensor unit 3 (ID4).

  Even if the wheel rotation is performed, as shown in the graph of FIG. 5, the position characteristic of each wheel 2 does not change. Therefore, the receiver unit controller 33 determines the position characteristic of each wheel 2 and the tire sensor unit 3 that has moved. The relationship with the ID code is updated. That is, the tire sensor unit 3 with ID4 is located on the front left side FL, and the tire sensor unit 3 with ID3 is located on the front right side FR. Similarly, the tire sensor unit 3 of ID1 is located on the rear left side RL, and the tire sensor unit 3 of ID2 is located on the rear right side RR. As a result, the position of the wheel 2 can be specified using the position characteristics even after the wheel rotation.

According to the above embodiment, the following effects can be obtained.
(1) In the position specifying operation of the wheel 2, the tire sensor unit 3 transmits an RF signal to the receiver unit 4 at every four rotation angles, and the receiver unit controller 33 at other rotation angles with respect to the reference angle. A reception intensity difference is acquired, and a unique position characteristic is acquired for each tire sensor unit 3, that is, for each position of the wheel 2, from the reception intensity difference. This position characteristic is peculiar to the position where the tire sensor unit 3 is installed, that is, the position of the wheel 2, and a solid output difference of the RF transmission circuit 16 or a decrease in output due to battery consumption of the tire sensor unit 3 occurs. It will not collapse. For this reason, by using the position characteristics of the wheel 2, even the position specifying operation of the wheel 2 using the reception intensity in the receiver unit 4 can be accurately performed.

  (2) Even if the wheel rotation is performed and the relationship between the position characteristic for each wheel 2 registered in the receiver unit controller 33 and the ID code is broken, the position characteristic for each wheel 2 is not changed. Therefore, the position specifying operation of the wheel 2 can be performed by using the position characteristic for each wheel 2 even after the wheel rotation.

(3) Since the position characteristic for each wheel 2 is registered in advance in the receiver unit controller 33, the position specifying operation can be performed promptly.
(4) For the position specifying operation of the tire sensor unit 3, there is also a method using ABS. In this method, when the tire sensor unit is positioned at a predetermined rotation angle of the wheel, an RF signal is transmitted to the receiver unit. In the receiver unit, the rotation angles of the four wheels 2 are acquired at the reception timing of the RF signal. In the receiver unit, it is possible to continue to obtain a rotation angle value that is approximately approximated for only one wheel, and the rotation angle varies for the other wheels. For this reason, in the receiver unit, the value of the rotation angle that is approximately approximate can be continuously acquired, and the wheel is identified as the wheel provided with the tire sensor unit that transmits the RF signal.

  However, in the method using ABS, for example, when the wheel outer diameter is the same and the air pressure is the same, and the vehicle is traveling straight, the value of the rotation angle obtained by ABS does not vary. It may take time until the position of the wheel 2 is specified. On the other hand, in this embodiment, since the ABS is not used, the position of the wheel 2 can be specified without being affected by the running state, the outer diameter of the tire, the air pressure, and the like. Further, the receiver unit 4 does not require wiring for obtaining the rotation angle from the ABS or a configuration for receiving data.

  (5) In the tire sensor unit 3, the RF transmission circuit 16 transmits an RF signal when the acceleration sensor 13 detects a predetermined acceleration. For this reason, it is possible to accurately transmit the RF signal at a predetermined rotation angle, and to accurately perform the directivity grasping operation.

  (6) The position characteristic can be set by the rotation angle obtained from the detection value of the acceleration sensor 13 and the reception intensity at the RF receiving antenna 32. Therefore, the position characteristics can be set with the existing configuration in the tire sensor unit 3 and the receiver unit 4, and the position specifying operation can be performed accurately without increasing the number of parts.

In addition, you may change this embodiment as follows.
In the embodiment, the sensor unit controller 14 performs the RF signal transmission operation at an interval different from the first and second predetermined time intervals during the position specifying operation of the wheel 2, but is not limited thereto. The sensor unit controller 14 may perform the RF signal transmission operation at the same time interval as the first predetermined time interval or the second predetermined time interval during the position specifying operation of the wheel 2.

○ The number of locations where RF signals are transmitted from the tire sensor unit 3 may be two or more and any number.
In the embodiment, the acceleration sensor 13 is a uniaxial acceleration sensor, but it may be a biaxial or triaxial acceleration sensor, and the detection axis may extend in the horizontal direction.

(Circle) this invention is not limited to application to a tire condition monitoring apparatus, It can apply to the various apparatuses which monitor the state of the wheel 2. FIG.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

(A) The wheel position specifying device includes an acceleration sensor, and the transmission unit transmits the signal based on the acceleration detected by the acceleration sensor.
(B) Each wheel side unit is a wheel position specifying device that is a tire sensor unit that wirelessly transmits a signal including data indicating the detected tire state while detecting the state of the tire in the wheel.

  (C) The wheel position specifying device is a wheel position specifying device applied to a tire condition monitoring device.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Wheel, 3 ... Tire sensor unit as wheel side unit, 4 ... Receiver unit, 11 ... Pressure sensor as state detection part, 12 ... Temperature sensor as state detection part, 16 ... As transmission part RF transmitting circuit, 33... Receiver unit controller as wheel position specifying unit, 35. RF receiving circuit as receiving unit.

Claims (2)

A wheel position specifying device for specifying positions of a plurality of wheels provided in a vehicle,
A wheel-side unit provided on each of the wheels, and a receiver unit installed on a vehicle body of the vehicle, the wheel-side unit is set with unique identification information, and the wheel-side unit is in a state of the wheel And a transmitter that wirelessly transmits a signal including the data detected by the state detector and the identification information, and the transmitter includes a plurality of reference angles including the reference angle in the wheel. Send the signal from the rotation angle,
The receiver unit includes a receiving unit for signals transmitted from each wheel side unit, and a wheel position specifying unit that specifies from which wheel side unit the signal is transmitted,
The wheel position specifying unit, for all wheel side units, relates to the reception strength of the signal at the reception unit, based on the magnitude relationship of the reception strength at other rotation angles with respect to the reception strength at the reference angle. , Respectively, and based on the position characteristics, the position of the wheel-side unit that specifies the position of the signal transmitted from the wheel-side unit is specified.   The wheel position specifying device according to claim 1, wherein the position characteristic is set in the wheel position specifying unit when the wheel side unit is installed in the vehicle.