JP5933472B2 - Tire wear detection device - Google Patents

Description

  The present invention relates to a tire wear detection device for detecting wear on a tread portion of a tire.

  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

  However, as in Patent Document 1, when a dedicated tire having a wear detection device embedded therein is used, when the tire is replaced, it must be replaced with a dedicated tire in order to enable subsequent wear detection. This will increase the burden on the vehicle user.

  An object of the present invention is to provide a tire wear detection device capable of detecting wear on a tread portion without using a dedicated tire in which a wear detection device is embedded.

In order to solve the above problem, the tire wear detection device according to claim 1 is a tire wear detection device that is mounted inside a tire of a vehicle and detects wear on a tread portion of the tire, And a pair of electrodes that are spaced apart from each other and bonded to the inner circumferential surface of the tire, and a capacitance of the electrodes when a voltage is applied from the power source to the pair of electrodes. a measuring circuit, based on said capacitance measured by the measurement circuit have a, a wear detector for detecting wear of said tread portion, a plurality of steel wires are embedded in the said tire, of said pair The gist of the electrodes is that the steel wires intersecting with one electrode are arranged at intervals so as not to intersect with the other electrode .

  According to this, when a voltage is applied to the pair of electrodes, lines of electric force are generated between the pair of electrodes. Since the area and distance of the pair of electrodes are constant, the number of lines of electric force leaking from the tire as a dielectric between the pair of electrodes is small as the wear of the tread portion does not progress, and the ratio of the tire Since the dielectric constant increases, the capacitance between the pair of electrodes increases. On the other hand, as the wear of the tire progresses, the amount of electric lines of force leaking from the tire increases and the relative permittivity of the tire decreases, so that the capacitance between the pair of electrodes decreases. And the electrostatic capacitance between a pair of electrodes is measured by a measuring circuit, and if this measured electrostatic capacitance becomes small, the wear detector can detect the wear of the tread portion. Therefore, the wear of the tread portion can be detected simply by joining a pair of electrodes to the inner peripheral surface of the tire and providing the power source, the measurement circuit, and the wear detection portion in the tire, and the wear detection device is embedded in the tire. Even if the tire is not a dedicated tire, the wear of the tread portion can be detected.

And when wear of a tread part advances and a tire is exchanged, the tire wear detecting device may be removed from the tire and installed on a new tire, so that the burden on the vehicle user does not increase. In addition, it is possible to prevent the pair of electrodes from being conducted by the steel wire, and to reliably generate lines of electric force between the pair of electrodes.

In addition, the tire wear detection device preferably includes a dew condensation removing unit that removes dew condensation generated on the electrode.
According to this, by removing the condensation generated on the electrodes by the condensation removing unit, it is possible to suppress the capacitance provided between the pair of electrodes from being reduced due to the condensation, and it is difficult to detect wear. It becomes easy to avoid.

In the tire wear detection device, the dew removal part may be a water repellent layer provided on the exposed surface of the electrode.
According to this, the water repellent layer can remove the condensation generated on the electrode, and the capacitance provided between the pair of electrodes is reduced by the condensation without increasing the number of parts of the tire wear detection device. This can be suppressed.

Further, in the tire wear detection device, the dew condensation removing unit may be a groove provided on a surface of the electrode opposite to the bonding surface to the tire.
According to this, the dew condensation generated on the electrode can be removed outside the electrode through the groove, and the capacitance provided between the pair of electrodes can be increased by the dew condensation without increasing the number of parts of the tire wear detection device. It can suppress that it becomes small.

In the tire wear detection device, it is preferable that the groove extends along a rotation direction of the tire.
According to this, the water | moisture content in a groove | channel can be blown out of an electrode along a groove | channel by rotation of a tire.

Also, the tire wear detection device, the installed in the tire inside, the tire sensor unit having a transmission unit for transmitting the tire information detected by the state detector and the state detector detects the state of the tire, the The vehicle has a tire condition monitoring device that is installed in a vehicle body and includes a receiver unit that includes a receiver that receives tire information transmitted by the tire sensor unit, and the power source of the tire wear detection device, The tire sensor unit may include the measurement circuit and the wear detection unit.

  According to this, the tire wear detection device can be provided in the tire simply by joining the pair of electrodes to the inner peripheral surface of the tire and installing the tire sensor unit in the tire.

  According to the present invention, it is possible to detect wear on a tread portion without using a dedicated tire in which a wear detection device is embedded.

The schematic block diagram which shows the vehicle by which the tire condition monitoring apparatus of embodiment is mounted. 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 a tire wear detection apparatus. The partial top view which shows the positional relationship of a pair of electrode and the steel wire in a tire. The figure which shows the tire wear detection apparatus which detects wear of a tread part. (A) is a partial fracture perspective view which shows the state which provided the groove | channel in the electrode, (b) is a partial expanded sectional view which shows an electrode and a groove | channel. The figure which shows background art.

Hereinafter, an embodiment in which the tire wear detection device is embodied will be described with reference to FIGS.
As shown in FIG. 1, the tire condition monitoring apparatus includes four tire sensor units 3 that are respectively attached to four wheels 2 of the vehicle 1 and a receiver unit 4 that is installed on the vehicle body of the vehicle 1. Each wheel 2 includes a wheel portion 5 and a tire 6 attached to the wheel portion 5. A tire wear detection device 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.

  As shown in FIGS. 2 and 3, 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 3 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 3 detects the state of the corresponding tire 6 (in-tire pressure) and the wear of the tread portion 7, and wirelessly transmits a signal including data indicating the detected tire state and the worn state.

  Each tire sensor unit 3 includes a pressure sensor 11, a sensor unit controller 14, a transmission circuit 16, a measurement circuit 17, and a power source 18 inside the case 3a, and a pair of electrodes 19 outside the case 3a. 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. In addition, the case 3 a is joined to the inner peripheral surface of the tire 6 so as to straddle the pair of electrodes 19. Further, each electrode 19 is an exposed surface into the tire 6 except for a joint surface to the inner peripheral surface of the tire 6, and this exposed surface is covered with a water repellent layer 19a as a dew condensation removing portion. ing.

As shown in FIG. 4, a plurality of steel wires W such as breaker cords and carcass cords are embedded in the tire 6.
As shown in FIG. 3, the tire sensor unit 3 operates by supplying power from a power source 18. The pressure sensor 11 as a state detector 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 3 is registered in the storage unit. This ID code is information used to identify each tire sensor unit 3 in the receiver unit 4. The sensor unit controller 14 outputs the tire pressure data to the transmission circuit 16. The transmission circuit 16 as a transmission unit modulates data to generate an RF signal, and wirelessly transmits the RF signal from the transmission antenna 21.

  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. A large number of steel wires W are embedded in the tire 6, but by spacing the electrodes 19 so that the steel wires W that intersect each electrode 19 do not intersect the other electrode 19, The electric lines of force F are generated 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 the voltage signal 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 3. 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 tire wear detection device includes a power supply 18 provided in the case 3a of the tire sensor unit 3, a measurement circuit 17, a sensor unit controller 14 (wear detection unit), and a pair outside the case 3a. The electrode 19 is provided.

  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 connected 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 a program for comprehensively controlling the operation of the receiver unit 4 is stored in the storage unit. 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.

  The receiver unit controller 33 grasps the in-tire pressure of the tire 6 corresponding to the tire sensor unit 3 that is the transmission source based on the RF signal and the ID code from the RF receiving circuit 35. The receiver unit controller 33 causes the display 38 to display information related to the tire internal pressure. 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 on the indicator 38. In addition, when receiving a warning signal from the tire sensor unit 3, the receiver unit controller 33 displays a warning regarding the wear of the tire 6 on the display 38.

Next, the operation of the tire wear detection device will be described.
As shown in FIG. 3, when a voltage is applied from the power source 18 to the pair of electrodes 19, electric lines of force F are generated between the pair of electrodes 19, and electrostatic capacitance is generated between the pair of electrodes 19. You can have it. Then, the measurement circuit 17 measures the electrostatic capacitance as a voltage, and outputs the measured voltage to the sensor unit controller 14. The sensor unit controller 14 compares the input voltage with a threshold value. If the voltage does not exceed the threshold value, the above alarm signal is not generated and the transmission operation by the transmission circuit 16 is not performed.

  On the other hand, as shown in FIG. 5, when the wear of the tread portion 7 progresses and the thickness of the tire 6 becomes thin, the amount of electric lines of force F leaking from the tire 6 increases, and the capacitance between the pair of electrodes 19 increases. As the voltage decreases, the voltage measured by the measurement circuit 17 also decreases. If the voltage input to the sensor unit controller 14 exceeds the threshold value, the sensor unit controller 14 generates an alarm signal and causes the transmission circuit 16 to transmit the alarm signal. In the receiver unit 4, the alarm signal is received by the RF receiving circuit 35 through the RF receiving antenna 32. The alarm signal received by the RF receiving circuit 35 is output to the receiver unit controller 33, and the receiver unit controller 33 causes the display 38 to display an alarm regarding tire wear.

According to the above embodiment, the following effects can be obtained.
(1) The tire wear detection device joins a pair of electrodes 19 to the inner peripheral surface of the tire 6 and wears the tread portion 7 based on a change in capacitance when a voltage is applied to the pair of electrodes 19. Can be detected. Therefore, it is possible to detect the wear of the tread portion 7 without burying a wear detecting device in the tire 6.

  (2) As for a pair of electrode 19, the exposed surface in the tire 6 is covered with the water-repellent processed layer 19a. For this reason, even if dew condensation occurs on the electrode 19, the water repellent function of the water repellent layer 19 a makes it difficult for moisture to remain attached to the electrode 19. If the tire 6 rotates, the moisture is quickly removed from the electrode 19. be able to. Therefore, it is possible to reliably detect wear of the tread portion 7 by avoiding that the capacitance between the pair of electrodes 19 is reduced due to moisture adhering to the electrodes 19.

  (3) Although many steel wires W are embedded in the tire 6, the electric lines of force F generated between the pair of electrodes 19 pass through the gaps between the steel wires W. Therefore, the electric lines of force F are not blocked by the steel wire W, and a capacitance can be provided between the pair of electrodes 19.

  (4) Among the tire wear detection devices, the measurement circuit 17, the power source 18, and the sensor unit controller 14 are provided in the case 3a of the tire sensor unit 3, and only the electrode 19 is provided outside the case 3a. The tire wear detection device can be easily attached to the inside of the tire 6 simply by joining the pair of electrodes 19 to the inner peripheral surface of the tire 6 and installing the tire sensor unit 3 inside the tire 6. In addition, unlike the case where the tire wear detection device and the tire sensor unit 3 are provided separately in the tire 6, it is possible to avoid an increase in the number of components in the tire 6 and an increase in the amount of the tire 6.

  (5) The pair of electrodes 19 are arranged at intervals so that the steel wires W intersecting with one electrode 19 do not intersect with the other electrode 19. For this reason, it is possible to prevent the pair of electrodes 19 from being conducted by the steel wire W, and it is possible to reliably generate the electric lines of force F between the pair of electrodes 19.

In addition, you may change this embodiment as follows.
○ As shown in FIGS. 6A and 6B, a plurality of grooves 19b may be provided as a dew condensation removing portion on the surface of the pair of electrodes 19 opposite to the bonding surface to the tire 6. Good. Each groove 19 b extends linearly in the rotation direction of the tire 6. Each groove 19 b is open at both ends along the rotation direction of the tire 6 at both ends of the electrode 19 along the rotation direction of the tire 6.

  If comprised in this way, if the dew condensation which generate | occur | produced in the electrode 19 enters into the groove | channel 19b, dew condensation (water | moisture content) can be removed outside the electrode 19 along the groove | channel 19b. Furthermore, the water in the groove 19b can be blown out of the electrode 19 along the groove 19b by the rotation of the tire 6. Therefore, it is possible to prevent the capacitance provided between the pair of electrodes 19 from decreasing due to condensation without increasing the number of parts of the tire wear detection device.

  Further, the groove 19b as the dew condensation removing part extends not in the direction of rotation of the tire 6 but in the axial direction of the tire 6 or extends radially from the center of the electrode 19 along the surface of the electrode 19. The shape, arrangement, depth, and the like of the groove 19b are not particularly limited.

In addition to providing the electrode 19 with the water repellent layer 19a, a groove 19b may be provided.
In the embodiment, a part of the tire wear detection device is provided in the case 3a of the tire sensor unit 3, the pair of electrodes 19 and the tire sensor unit 3 are integrated, and the tire wear detection device and the tire sensor unit 3 are integrated. However, it is not limited to this. The tire sensor unit 3 and the tire wear detection device may be provided in the tire 6 separately.

  O The dew condensation removing unit may be a heater provided in the tire 6 instead of the water repellent layer 19a and the groove 19b. If comprised in this way, even if dew condensation arises in the electrode 19, the water | moisture content of the electrode 19 can be heated and evaporated with a heater, and a water | moisture content can be removed from the electrode 19. FIG.

The pair of electrodes 19 need not have the same size and the same shape.
The tire wear detection device is not limited to the application to the tire 6 in the four-wheel vehicle 1 but may be applied to the tire in the two-wheel vehicle.

The transmission unit of the tire sensor unit 3 may be a transmission circuit that generates an LF signal instead of the transmission circuit 16 that generates an RF signal.
The receiving unit of the receiver unit 4 may be a low-frequency receiving circuit instead of the RF receiving circuit 35.

  The state detector may be a temperature sensor or a humidity sensor in addition to the pressure sensor 11.

  W: Steel wire, 1 ... Vehicle, 3 ... Tire sensor unit, 4 ... Receiver unit, 6 ... Tire, 7 ... Tread part, 11 ... Pressure sensor as state detector, 14 ... Sensor unit controller as wear detector 16 ... Transmitting circuit as transmitting unit, 17 ... Measuring circuit, 18 ... Power source, 19 ... Electrode, 19a ... Water repellent layer as dew condensation removing unit, 19b ... Groove as dew removing unit, 35 ... As receiving unit RF receiver circuit.

Claims (6)

A tire wear detection device mounted on the inside of a vehicle tire for detecting wear on a tread portion of the tire,
Power supply,
A pair of electrodes that are spaced apart from each other and bonded to the inner circumferential surface of the tire in an insulated state;
A measurement circuit that measures the capacitance of the electrodes when a voltage is applied to the pair of electrodes from the power source;
Have a, a wear detector for detecting wear of the tread portion based on the electrostatic capacitance measured by the measuring circuit,
Tire wear detection in which a plurality of steel wires are embedded in the tire, and the pair of electrodes are spaced apart so that the steel wires that intersect one electrode do not intersect the other electrode apparatus.   The tire wear detection device according to claim 1, further comprising a dew condensation removing unit that removes dew condensation generated on the electrode.   The tire wear detection device according to claim 2, wherein the dew condensation removing unit is a water repellent layer provided on an exposed surface of the electrode.   4. The tire wear detection device according to claim 2, wherein the dew condensation removing portion is a groove provided on a surface of the electrode opposite to a bonding surface to the tire. 5.   The tire wear detection device according to claim 4, wherein the groove extends along a rotation direction of the tire. A tire sensor unit that is installed inside the tire and detects a state of the tire; a tire sensor unit that includes a transmission unit that transmits tire information detected by the state detector; and the tire sensor unit that is installed in a vehicle body of the vehicle. The vehicle has a tire condition monitoring device that includes a receiver unit that includes a receiving unit that receives tire information transmitted from the sensor unit, and the power source, the measurement circuit, and the wear detection unit of the tire wear detection device include: The tire wear detection device according to any one of claims 1 to 5 , wherein the tire sensor unit is provided.