JP6084515B2 - Wheel position determination device - Google Patents

Description

  The present invention relates to a wheel position determination device that determines the position of a wheel.

  Conventionally, various devices have been proposed as tire wear detection devices for detecting wear of tires (specifically, tread portions). For example, as shown in FIG. 7, the tire wear detection device disclosed in Patent Document 1 is installed in a vehicle body, a wear detector 82 embedded in a tread portion 81 of a tire 80, a sensor unit 84 provided in a wheel 83, and a vehicle body. Receiver unit (not shown). The wear detector 82 includes a piezoelectric element and a resonance circuit that generates a radio wave signal from a voltage signal generated by the piezoelectric element. In the wear detector 82, as wear of the tread portion 81 progresses, the impact that the piezoelectric element receives from the road surface increases, and the level of the voltage signal generated by the piezoelectric element also increases. For this reason, the level (intensity) of the radio signal generated by the resonance circuit also increases.

  The sensor unit 84 wirelessly transmits a pressure data signal indicating the internal air pressure of the tire 80, receives the radio signal generated by the wear detector 82, and wear data signal indicating the wear state of the tire 80 based on the received radio signal. And the wear data signal is transmitted wirelessly. The receiver unit receives the pressure data signal and the wear data signal from the sensor unit 84, and determines the wear state of the tire 80 based on the received wear data signal.

JP 2011-189795 A

  By the way, in the tire wear detection device, which of the plurality of tires 80 the tire unit 80 provided in which of the plurality of tires 80 is transmitted, in other words, the received data signal. It is necessary to determine at the receiver unit the position of the tire 80 (wheel) associated with the. As a wheel position specifying method, for example, identification information is set in the sensor unit 84, and a wheel position and identification information are registered in the receiver unit in advance. Then, the sensor unit 84 wirelessly transmits the identification information together with each data signal, thereby specifying the position of the wheel that wirelessly transmitted each data signal by the receiver unit. However, when the position of each tire 80 changes due to tire rotation or the like, the identification information registered in the receiver unit and the position of the wheel are changed. Then, the receiver unit cannot accurately determine which wheel the transmitted wear data signal belongs to.

  An object of the present invention is to provide a wheel position determination device that can determine a correct wheel position even if the wheel position is changed.

A wheel position determination device that solves the above problems is provided in a vehicle that includes a plurality of wheels with tires attached to a wheel portion, and includes a rotation position detection unit that detects a rotation position of the wheel corresponding to each wheel, A vehicle position determination device for determining a position of the wheel, wherein the plurality of wheels are joined to an inner peripheral surface of the tire in a state of being separated from each other and insulated from each other along an axial direction of the tire. A pair of electrodes formed, a power source provided in a case of the tire sensor unit, a measurement circuit for measuring a capacitance when a voltage is applied to the electrode, and wear of a tread portion of the tire based on the capacitance a wear detector for detecting a said a transmission circuit for outputting as a transmission signal capacitance measured by the measuring circuit, have a, and a wheel-side control unit for transmitting the transmission signal, wherein the case Wear detection apparatus that is joined to the inner peripheral surface of the tire in a state straddling the pair of electrodes are provided, the vehicle includes a receiving circuit for receiving a transmission signal transmitted from the transmitting circuit, transmitting the transmission signal A vehicle-side control unit that determines the position of the wear detection device, and the wheel-side control unit causes the transmission signal to be transmitted at a predetermined position based on the measured capacitance, The gist of the vehicle-side control unit is to collate the rotational position of each wheel at the time when the receiving circuit receives the transmission signal and determine the position of the wear detection device that has transmitted the transmission signal.

  The wheels rotate as the vehicle travels. At this time, the number of rotations of each wheel is different. For this reason, when the vehicle is traveling, the rotational speed of each wheel varies, and the relative position of the electrodes provided on each wheel changes. Here, the capacitance value measured by the measurement circuit differs depending on the rotation position of the pair of electrodes on the wheel, and a substantially constant value is measured at a certain position. Therefore, every time the electrode is positioned at a certain position, the wheel side control unit transmits a transmission signal. And when a receiving circuit receives the transmission signal transmitted from the wear detection apparatus provided in a certain wheel, a vehicle side control part acquires the rotation position of each wheel from each rotation position detection part. Then, since the obtained rotation position has a substantially constant value, it can be determined that the wheel corresponding to the rotation position detection unit that continuously detects the rotation position of the constant value is the wear detection device that has transmitted the transmission signal. For this reason, even if the wheel position is changed, the correct wheel position can be determined.

In the wheel position determination device, the fixed position is preferably when the pair of electrodes are grounded with the tire interposed therebetween.
According to this, at the position where the pair of electrodes are grounded with the tire sandwiched between them, the tire and the road become a dielectric, and the relative permittivity of the dielectric is larger than the case where only the tire is a dielectric. Also grows. Therefore, by outputting the transmission signal at the position where the electrostatic capacitance is maximized, it is possible to output the transmission signal accurately when the electrode is at a certain position.

About the said wheel position determination apparatus, it is preferable that the said rotational position detection part has a gearwheel which rotates integrally with the said wheel, and a detector arrange | positioned so as to oppose the outer peripheral surface of the said gearwheel.
According to this, since the gear and the detector are devices generally provided in the vehicle (so-called ABS), the rotational position of the wheel can be detected using this device.

  According to the present invention, the correct wheel position can be determined even if the wheel position is changed.

The schematic block diagram which shows the vehicle by which the tire condition monitoring apparatus of embodiment is mounted. The schematic block diagram which shows a rotation sensor unit. The fragmentary perspective view which shows the electrode in a tire, and a tire sensor unit. The figure which shows the circuit structure of a tire sensor unit and an abrasion detection apparatus. The schematic diagram which shows the positional relationship of an electrostatic capacitance and an electrode. The schematic diagram which shows the relationship of the rotation position of each wheel. The figure which shows background art.

Hereinafter, an embodiment in which the wheel position determination device is embodied will be described with reference to FIGS.
As shown in FIG. 1, the vehicle 10 is equipped with an ABS (anti-lock / brake system) 20 and a tire condition monitoring device 30. The ABS 20 includes an ABS controller 25 and rotation sensor units 21 to 24 respectively corresponding to the four wheels 1 to 4 of the vehicle 10. Each wheel 1-4 is comprised from the tire 6 with which the wheel part 5 and the wheel part 5 are mounted | worn. The ABS controller 25 is composed of a microcomputer or the like, obtains the rotational speed (rotational position) of each wheel 1 to 4 based on signals from the rotation sensor units 21 to 24, and based on this rotational speed, the slip rate of each wheel 1 to 4 Ask for. When the brake pedal (not shown) of the vehicle is depressed, the ABS controller 25 is a brake device (see FIG. 4) corresponding to each wheel 1-4 so that the slip rate of each wheel 1-4 does not exceed a predetermined allowable value. (Not shown) is controlled to adjust the braking force for each of the wheels 1 to 4. The wheel 1 is provided on the front left side, and the wheel 2 is provided on the front right side. The wheel 3 is provided on the rear left side, and the wheel 4 is provided on the rear right side. The rotation sensor unit 21 corresponds to a wheel provided on the front left side, and the rotation sensor unit 22 corresponds to a wheel provided on the front right side. The rotation sensor unit 23 corresponds to a wheel provided on the rear left side, and the rotation sensor unit 24 is provided corresponding to a wheel provided on the rear right side.

  As shown in FIG. 2, each rotation sensor unit 21 to 24 as a rotation position detection unit is provided near the wheels 1 to 4 and under a spring, and a gear 24 a that rotates integrally with the wheels 1 to 4, And a detector 24b arranged to face the outer peripheral surface of the gear 24a. A plurality of teeth (48 in this embodiment) are provided at equal angular intervals on the outer peripheral surface of the gear 24a. The detector 24b generates a pulse signal from the tooth position of the gear 24a. More specifically, the detector 24b detects the position of a tooth facing the detector 24b when wheels 1 to 4 described later are at a fixed position, and a signal related to the rotational position of the wheels 1 to 4 from the position of the tooth. (Pulse signal) is generated. The ABS controller 25 is wired to each detector 24b and obtains the rotational position of each wheel 1-4 based on the pulse signal from each detector 24b.

Next, the tire condition monitoring device 30 will be described.
As shown in FIG. 1, the tire condition monitoring device 30 includes four tire sensor units 13 that are respectively attached to the four wheels 1 to 4 of the vehicle 10, and a receiver unit 31 that is installed on the vehicle body of the vehicle 10. ing.

  As shown in FIG. 3, a wear detection device 40 is mounted inside the tire 6. The direction in which the central axis of the tire 6 extends is the axial direction of the tire 6, and the rotational direction of the wheel 2 is the rotational direction of the tire 6.

  The tire 6 includes a plurality of tread grooves 8 extending in the rotation direction in the axial direction, and includes a tread portion 7 in contact with the road surface between the tread grooves 8 adjacent in the axial direction. Each tire sensor unit 13 is installed on the inner peripheral surface of the tire 6 so as to be disposed in the internal space of the tire 6. Each tire sensor unit 13 detects the state of the corresponding tire 6 (in-tire pressure) and the wear of the tread portion 7, and transmits data including the detected tire state (including the worn state of the tire 6). Wireless transmission of signals.

  As shown in FIG. 4, each tire sensor unit 13 includes a pressure sensor 11, a sensor unit controller 14, a transmission circuit 16, a measurement circuit 17, and a power source 18 in a case 13a, and a pair of electrodes 19 outside the case 13a. Prepare for. The pair of electrodes 19 are rectangular plates of the same size, and are joined to the inner peripheral surface of the tire 6 in a state where they are insulated from each other with an interval along the axial direction of the tire 6. The case 13 a is joined to the inner peripheral surface of the tire 6 in a state of straddling the pair of electrodes 19.

  The tire sensor unit 13 operates by supplying power from the power source 18. The pressure sensor 11 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 sensor unit controller 14 includes a microcomputer including a CPU and a storage unit (RAM, ROM, etc.), and an ID code as identification information unique to each tire sensor unit 13 is registered in the storage unit. This ID code is information used to identify each tire sensor unit 13 in the receiver unit 31. The sensor unit controller 14 outputs the tire pressure data to the transmission circuit 16. The transmission circuit 16 modulates data and generates an RF signal. The sensor unit controller 14 wirelessly transmits an RF signal from the transmission antenna 26.

  The pair of electrodes 19 is electrically connected to the power source 18 via the measurement circuit 17, and a voltage is applied to the pair of electrodes 19 by the power source 18. When a voltage is applied to the pair of electrodes 19, electric lines of force F are generated between the pair of electrodes 19, and electrons move between the pair of electrodes 19. Since the tire 6 as a dielectric is interposed between the pair of electrodes 19, an electrostatic capacity can be provided between the pair of electrodes 19. This capacitance depends on the amount of electric force lines F passing through the tire 6, and the amount of electric force lines F leaking from the tire 6 is so small that the wear of the tread portion 7 does not progress. Since the ratio increases, the capacitance between the pair of electrodes 19 increases. On the other hand, as the wear of the tread portion 7 progresses, the amount of electric lines of force F leaking from the tire 6 increases and the relative dielectric constant of the tire 6 decreases, so that the capacitance between the pair of electrodes 19 decreases.

  The measurement circuit 17 is electrically connected to the pair of electrodes 19, and the measurement circuit 17 detects the capacitance between the pair of electrodes 19 as a voltage. The measurement circuit 17 is signal-connected to the sensor unit controller 14, and a signal related to the capacitance measured by the measurement circuit 17 is output to the sensor unit controller 14.

  The storage unit of the sensor unit controller 14 stores an overall program that comprehensively controls the operation of the tire sensor unit 13. The sensor unit controller 14 applies a voltage to the pair of electrodes 19 a plurality of times while the wheels 1 to 4 (tire 6) rotate once (during a certain period), and each time the wheel is applied, the pair of electrodes 19 The measurement circuit 17 is caused to measure the capacitance between 19. Therefore, a plurality of capacitances are input to the sensor unit controller 14 during a certain period, and the plurality of capacitances are stored in the storage unit.

  The sensor unit controller 14 acquires the maximum value from a plurality of capacitances. As shown in FIG. 5, the maximum value of the capacitance is when the pair of electrodes 19 are grounded on the road surface with the tire 6 in between. This is because the tire 6 and the road become a dielectric, and the dielectric constant of the dielectric increases, so that the electrostatic capacity also increases. On the other hand, when the pair of electrodes 19 are not grounded on the road surface with the tire 6 in between, the capacitance is smaller than that at the time of grounding.

  The sensor unit controller 14 as the wheel side control unit causes the transmission circuit 16 to output a transmission signal when the electrostatic capacitance is the maximum value, and causes the transmission antenna 26 to transmit the transmission signal. As described above, the capacitance has the maximum value when the pair of electrodes 19 are grounded with the tire 6 interposed therebetween. For this reason, the transmission circuit 16 provided in each tire 6 outputs a transmission signal at a position where the electrode 19 is in a fixed position, that is, a position where the pair of electrodes 19 are grounded with the tire 6 in between.

  In addition, a threshold for comparison with the voltage (capacitance) measured by the measurement circuit 17 is stored in advance in the storage unit of the sensor unit controller 14. The threshold is set with a margin more than the voltage (capacitance) detected when the wear of the tread portion 7 proceeds excessively. When the voltage detected by the measurement circuit 17 exceeds the threshold value, the sensor unit controller 14 generates an alarm signal and transmits it from the transmission circuit 16. On the other hand, the sensor unit controller 14 does not generate an alarm signal when the voltage detected by the measurement circuit 17 does not exceed the threshold value. Therefore, in this embodiment, the sensor unit controller 14 constitutes a wear detection unit that detects wear of the tread portion 7. In the present embodiment, the wear detection device 40 includes a power source 18 provided in the case 13a of the tire sensor unit 13, a measurement circuit 17, a sensor unit controller 14 (wear detection unit), a transmission circuit 16, and A transmission antenna 26 and a pair of electrodes 19 outside the case 13a are provided.

  As shown in FIG. 1, the receiver unit 31 includes a receiver unit controller 33 and an RF receiving circuit 35 as a receiving circuit. A display unit 38 is connected to the receiver unit controller 33 of the receiver unit 31. The receiver unit controller 33 is composed of a microcomputer including a CPU and a storage unit (ROM, RAM, etc.), and a program for comprehensively controlling the operation of the receiver unit 31 is stored in the storage unit. The RF receiving circuit 35 demodulates the RF signal received from each tire sensor unit 13 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 state of the tire 6 (the tire internal pressure and the tire wear state) corresponding to the tire sensor unit 13 of the transmission source. The receiver unit controller 33 causes the display 38 to display information related to the tire internal pressure. The indicator 38 is arranged in the visible range of the passenger of the vehicle 10 such as in the passenger compartment, and the receiver unit controller 33 displays (informs) an abnormality in the tire pressure on the indicator 38. In addition, when receiving a warning signal from the tire sensor unit 13, the receiver unit controller 33 displays a warning regarding the wear of the tire 6 on the display 38.

  The receiver unit controller 33 is connected to the ABS controller 25 and receives the pulse signals generated by the rotation sensor units 21 to 24 through the ABS controller 25. Further, when the receiver unit controller 33 receives the transmission signal output from the transmission circuit 16, when the RF reception circuit 35 receives the transmission signal, the receiver unit controller 33 outputs the pulse signals generated by the rotation sensor units 21 to 24. Acquire and specify the rotational position of the wheels 1 to 4.

  The number of rotations of each of the wheels 1 to 4 differs depending on the influence of a differential gear, right / left turn, and the like. As described above, the transmission circuit 16 provided on each of the wheels 1 to 4 outputs a transmission signal when the pair of electrodes are grounded with the tire 6 interposed therebetween.

  As shown in FIG. 6, for example, when attention is paid to the transmission circuit 16 provided on the wheel 1, when the electrode 19 provided on the wheel 1 is grounded with the tire 6 interposed therebetween (time t1, t2, t3, t4). Since the transmission signal is output, the transmission circuit 16 provided in the wheel 1 outputs the transmission signal when the rotational position of the wheel 1 is always the same position. On the other hand, since the rotational speeds of the wheels 1 to 4 are different, the rotational positions of the wheels 2 to 4 when the transmission circuit 16 provided in the wheel 1 outputs a transmission signal (time t1, t2, t3, t4) Variation occurs. Similarly, when the transmission circuit 16 provided on the wheel 2 outputs a transmission signal, the rotational position of the wheel 2 is always the same, but the rotational positions of the wheels 1, 3 and 4 vary. The same applies to the wheels 3 and 4. Note that the transmission circuit 16 ideally outputs when the rotational positions of the wheels 1 to 4 provided with the transmission circuits 16 are the same, but in practice, due to the measurement error associated with the running state, etc. There is some variation in the position where the transmission circuit 16 performs transmission. Therefore, the fixed position from which the transmission circuit 16 outputs a transmission signal indicates a position within a certain range including variations due to errors and the like.

  The receiver unit controller 33 as the vehicle side control unit acquires the pulse signals of the wheels 1 to 4 from the ABS controller 25 when the RF receiving circuit 35 receives the transmission signal, and each wheel 1 based on the pulse signal. Determine the position of ~ 4. At this time, the receiver unit controller 33 can determine the wheel having the smallest variation in the value of the pulse signal as the wheels 1 to 4 provided with the transmission circuit 16 that transmits the transmission signal. Therefore, the wheel position determination device of the present embodiment includes the transmission circuit 16, the measurement circuit 17, the power supply 18, the electrode 19, the sensor unit controller 14, the rotation sensor units 21 to 24, and the receiver unit 31 of the wear detection device 40. An RF receiving circuit 35 and a receiver unit controller 33 are included.

Next, the operation of the wheel position determination device of this embodiment will be described.
As indicated by an arrow Y1 in FIG. 1, for example, the wheel 1 is provided on the rear left side, the wheel 2 is provided on the rear right side, the wheel 3 is provided on the front right side, and the wheel 4 is on the front side. When provided on the left side, the ID code registered in the receiver unit controller 33 does not correspond to the tire sensor unit 13. Then, even if information about the tire condition is transmitted from the tire sensor unit 13, the transmission source cannot be specified. For this reason, after changing the wheel position, it is necessary to update the correspondence between the ID code of the tire sensor unit 13 and the wheel position and store it in the receiver unit controller 33, which takes time.

  In the present embodiment, the position of each wheel 1 to 4 is referred to a plurality of times when the maximum value of the capacitance is detected by the wear detection device 40 and the RF reception circuit 35 receives the transmission signal transmitted from the wheel 1. Then, the variation in the rotational position of the wheel 1 detected by the rotation sensor unit 23 is minimized. Since the rotation sensor unit 23 is a sensor unit corresponding to a wheel provided on the rear left side, it can be determined that the wheel 1 that has transmitted the transmission signal is provided on the rear left side. Similarly, the wheel positions of the wheels 2 to 4 can be determined. The receiver unit controller 33 can determine which wheel of the four wheels 1 to 4 is the transmission signal transmitted from the transmission circuit 16 from the ID code.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The capacitance is measured using the electrode 19 of the wear detection device 40. The transmission circuit 16 provided on each of the wheels 1 to 4 outputs a transmission signal when the electrostatic capacitance reaches the maximum value, so that the transmission signal is output every time the electrode 19 is positioned at a certain position. Is output. The receiver unit controller 33 detects the rotation positions of the wheels 1 to 4 at the time when the RF reception circuit 35 receives the transmission signal transmitted from the transmission circuit 16 by the rotation sensor units 21 to 24. By comparing the rotational positions of the wheels 1 to 4 when the transmission signal is transmitted, the positions of the wheels 1 to 4 can be determined, and even when the wheel position is changed, the correct wheel position is determined. be able to. The rotation positions of the wheels 1 to 4 can be detected by the rotation sensor units 21 to 24 of the ABS 20. For this reason, the position of the wheels 1-4 can be specified using the wear detection device 40 and the ABS 20, and the wheel position determination device can be configured using the existing configuration. A dedicated member for providing the wheel position determination device is not necessary, and the wheel position determination device can be provided with a simple configuration.

  (2) The transmission circuit 16 outputs a transmission signal when the electrode 19 is grounded with the tire 6 in between. When the electrode 19 is grounded with the tire 6 in between, the electrostatic capacity is maximized. When the electrostatic capacity is maximized, the transmission circuit 16 outputs a transmission signal so that the electrode 19 is at a fixed position. It is possible to cause the transmission circuit 16 to output a transmission signal accurately.

  (3) As the rotation position detection unit, a gear 24a that rotates integrally and a detector 24b that is disposed so as to face the outer peripheral surface of the gear 24a are used. For this reason, the rotational position of the wheels 1 to 4 can be detected using the ABS 20 provided in the vehicle 10.

In addition, you may change embodiment as follows.
The fixed position where the transmission circuit 16 outputs a transmission signal may not be when the electrode 19 is grounded with the tire 6 interposed therebetween. For example, the transmission circuit 16 may output a transmission signal when the electrode 19 rotates a certain number of times after being grounded with the tire 6 in between.

  -You may use a magnetic sensor as a rotation position detection part. In this case, for example, a magnetic material is installed in a wheel house or the like of the vehicle 10, and the electrostatic capacity is measured when the magnetic force of the magnetic material is detected by a magnetic sensor as the tire 6 rotates.

  In the embodiment, a part of the wear detection device 40 is provided in the case 13a of the tire sensor unit 13, the pair of electrodes 19 and the tire sensor unit 13 are integrated, and the wear detection device 40 and the tire sensor unit 13 are integrated. However, it is not limited to this. The tire sensor unit 13 and the wear detection device 40 may be provided in the tire 6 separately.

The pair of electrodes 19 need not have the same size and the same shape.
The wear detection device 40 is not limited to the application to the tire 6 in the four-wheel vehicle 10, and may be applied to a tire in a vehicle other than the four wheels such as a two-wheel or a three-wheel.

The transmission circuit 16 of the tire sensor unit 13 may be a transmission circuit 16 that generates an LF signal instead of the transmission circuit 16 that generates an RF signal.
The receiving circuit of the receiver unit 31 may be a low frequency receiving circuit instead of the RF receiving circuit 35.

  DESCRIPTION OF SYMBOLS 1-4 ... Wheel, 5 ... Wheel part, 6 ... Tire, 10 ... Vehicle, 13 ... Tire sensor unit, 14 ... Sensor unit controller, 16 ... Transmission circuit, 17 ... Measuring circuit, 18 ... Power supply, 19 ... Electrode, 21 -24 ... Rotation sensor unit, 24a ... gear, 24b ... detector, 33 ... receiver unit controller, 35 ... RF receiving circuit, 40 ... wear detection device.

Claims (3)

A vehicle position determination device that includes a plurality of wheels with tires attached to a wheel portion, and is provided in a vehicle that includes a rotation position detection unit that detects the rotation position of the wheel corresponding to each wheel, and determines the position of the wheel. Because
The plurality of wheels include a pair of electrodes that are spaced apart from each other along an axial direction of the tire and are joined to the inner peripheral surface of the tire in an insulated state, and a tire sensor unit case. Measured by a power supply, a measurement circuit that measures capacitance when a voltage is applied to the electrode, a wear detection unit that detects wear of a tread portion of the tire based on the capacitance, and the measurement circuit a transmission circuit for outputting a capacitance as a transmission signal, said a wheel-side control unit for transmitting a transmission signal, have a, wherein the case is bonded to the inner peripheral surface of the tire in a state straddling the pair of electrodes wear A detection device is provided,
The vehicle is provided with a receiving circuit that receives a transmission signal transmitted from the transmission circuit, and a vehicle-side control unit that determines the position of the wear detection device that has transmitted the transmission signal,
The wheel side control unit, based on the measured capacitance, causes the transmission signal to be transmitted at a predetermined position,
The vehicle-side control unit collates the rotational position of each wheel at the time when the reception circuit receives the transmission signal, and determines the position of the wear detection device that transmitted the transmission signal. apparatus.   The wheel position determination device according to claim 1, wherein the fixed position is when the pair of electrodes are grounded with the tire interposed therebetween.   The wheel position determination device according to claim 1, wherein the rotation position detection unit includes a gear that rotates integrally with the wheel, and a detector that is disposed so as to face an outer peripheral surface of the gear.