JP2013067244A - Vehicle wheel position determining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle wheel position determining device that can determine right-and-left positions of vehicle wheels with a low-cost configuration.SOLUTION: Each tire sensor unit 3 includes a distortion sensor 20 for detecting a distortion of a base plate 21 caused by an acceleration of a traveling vehicle, and generating a data signal according to the distortion, and a transmission antenna 19 for radio-transmitting the data signal. A receiver unit controller of a receiver unit determines, based on information relating to the distortion included in a received data signal, whether the received data signal is the data signal transmitted from the tire sensor unit 3 provided on a left wheel of the vehicle or the data signal transmitted from the tire sensor unit 3 provided on a right wheel of the vehicle.

Description

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

  For example, Patent Document 1 proposes a wireless tire condition monitoring apparatus as an apparatus for enabling a driver to check the condition of a plurality of tires provided in a vehicle in a passenger compartment. The tire condition monitoring device described in Patent Literature 1 includes a plurality of transmitters that are respectively mounted on the wheels of a vehicle and a receiver that is mounted on a vehicle body of the vehicle. Each transmitter detects the state of the corresponding tire, that is, the pressure and temperature in the tire, and wirelessly transmits a data signal including data indicating the detected tire state. On the other hand, the receiver receives a data signal from each transmitter through the receiving antenna, and displays information on the tire condition on a display provided in the vehicle interior as necessary. The receiver includes four transmitters so as to correspond to the four transmitters. When a trigger signal is wirelessly transmitted from each transmitter, and the transmitter detects a trigger signal from the corresponding transmitter, the tire state is detected.

  In the tire condition monitoring device as described above, it is related to the received data signal whether the received data signal is transmitted from which transmitter among the plurality of tires. It is desirable to be able to determine the position of the tire (wheel) to be performed at the receiver. So, in the said patent document 1, each transmitter is provided with an angular acceleration sensor, respectively. When the vehicle is accelerated, the angular acceleration value output from the angular acceleration sensor in the transmitter has a different polarity between the left tire and the right tire, so that the controller of each transmitter receives the angular acceleration from the angular acceleration sensor. Based on the data, it is determined whether the tire is provided on the left or right tire.

JP 2004-262324 A

However, in patent document 1, in order to detect a tire condition, four transmitters are required corresponding to each transmitter, and the cost of the tire condition monitoring device increases.
The objective of this invention is providing the wheel position determination apparatus which can determine the left-right position of a wheel with an inexpensive structure.

  In order to solve the above problems, the invention according to claim 1 is a wheel position determination device for determining the positions of a plurality of wheels provided in a vehicle, wherein the wheel side unit is provided in each of the wheels. And a receiver unit installed on the vehicle body of the vehicle, wherein each wheel side unit detects a strain of the object to be measured accompanying acceleration or deceleration of the vehicle and generates a data signal corresponding to the strain. A strain sensor; and a transmitter that wirelessly transmits the data signal, wherein the receiver unit receives a data signal transmitted from each wheel side unit through a reception antenna; and a received data signal Whether the data signal is a data signal transmitted from the wheel side unit provided on the left wheel of the vehicle based on the information on the strain included in the vehicle Having a determining wheel position determination unit whether a transmitted data signal from said wheel-side unit provided.

  According to this, when the vehicle is accelerated or decelerated, distortion due to acceleration or deceleration is generated in the object to be measured due to acceleration or deceleration in the circumferential direction of the wheel. Since the rotation direction is reversed between the left wheel and the right wheel, the strain value is also reversed between the left wheel and the right wheel, and a difference occurs in the data signal generated from the strain sensor. Based on the difference in strain value, the wheel position determination unit determines whether the wheel unit to which the data signal is transmitted is provided on the left wheel or the right wheel. be able to. If the left and right positions of the wheels can be determined by the wheel position determination unit, the state of the wheel at each position can be grasped by the receiver unit. Therefore, according to the present invention, as in the background art, the receiver unit can detect and grasp the state of the wheel without requiring a transmitter corresponding to each wheel side unit. The wheel position determination device can be made cheaper than when a transmitter is required for each wheel.

  Each of the wheel side units includes an acceleration sensor that rotates together with the wheel and generates a data signal reflecting centrifugal acceleration, and the wheel position determination unit is triggered by the fact that the centrifugal acceleration is changing from zero. Whether the vehicle is in a starting state, or whether the vehicle is in a stopped state when the centrifugal acceleration is changing to zero, and the vehicle is in the starting state or the When it is determined that the vehicle is stopped, the left and right positions of the wheels may be determined based on the data signal of the strain sensor.

  According to this, when the vehicle is in a constant speed running state, the strain value detected by the strain sensor is substantially the same for the left wheel and the right wheel, and the wheel position determination unit determines the difference in strain. This makes it difficult to determine the left and right positions of the wheels. The state of the vehicle when the centrifugal acceleration is changed from zero by the acceleration sensor or when the centrifugal acceleration is changed to zero is not a constant speed running state but a starting state or a stopped state. For this reason, by using an acceleration sensor, it can be determined that the vehicle is in a starting state or a stopping state, and the left wheel and the right wheel are in a starting state or a stopping state with different strain values. Sometimes the left and right positions of the wheels can be determined. As a result, it is possible to eliminate a useless determination process in which the wheel position determination unit becomes unable to determine the right and left positions of the wheels during constant speed traveling.

The object to be measured may be a substrate of the wheel side unit.
According to this, since the strain sensor is housed in the wheel side unit, the left and right positions of the wheel can be determined without increasing the size of the wheel side unit.

  According to the present invention, the left and right positions of the wheels can be determined with an inexpensive configuration.

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 the tire sensor unit of FIG. The figure which shows a wheel partially broken in order to show arrangement | positioning of a tire sensor unit.

Below, one Embodiment which actualized the wheel position determination apparatus of this invention to the tire condition monitoring apparatus is 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. In the following, the front left wheel 2 is indicated by reference symbol FL, the front right wheel 2 is indicated by reference symbol FR, the rear left wheel 2 is indicated by reference symbol RL, and the rear right wheel 2 is indicated by reference symbol RR. Show.

  Each tire sensor unit 3 as a wheel side unit is attached to a wheel portion 5 to which the tire 6 is attached 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 includes a signal including data indicating the detected tire state, that is, a tire state data signal (hereinafter referred to as a data signal). Radio).

  As shown in FIG. 3, in each tire sensor unit 3, a substrate 21 is housed in the case 3a. As shown in FIG. 2, the substrate 21 includes a pressure sensor 11, a temperature sensor 12, and an acceleration sensor. 13, a strain sensor 20, a sensor unit controller 14, and an RF transmission circuit 16 as a transmission unit are provided. The pressure sensor 11, the temperature sensor 12, the acceleration sensor 13, the strain sensor 20, the sensor unit controller 14, and the RF transmission circuit 16 are driven by electric power supplied from a battery 22 built in the tire sensor unit 3.

  The pressure sensor 11 detects the pressure (internal air pressure) in the corresponding tire 6 and outputs tire pressure data obtained by the detection to the sensor unit controller 14. The temperature sensor 12 detects the temperature (internal air temperature) in the corresponding tire 6 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. In the present embodiment, the acceleration sensor 13 is a uniaxial acceleration sensor, that is, in a direction along one detection axis. An acceleration sensor capable of detecting an acceleration component is used. As shown in FIG. 3, the acceleration sensor 13 is arranged on the substrate 21 so that the acceleration detection direction (that is, the detection axis) 10 coincides with the radial direction of the wheel 2.

  Then, the acceleration sensor 13 detects the acceleration of the corresponding wheel 2 and outputs tire acceleration data obtained by the detection to the sensor unit controller 14. For example, the wheel 2 outputs to the sensor unit controller 14 acceleration data whose value increases when the vehicle 1 starts or accelerates, and acceleration data whose value decreases when the vehicle 1 stops or decelerates.

  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 that is 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 and is included in a transmission signal from the sensor unit controller 14. The sensor unit controller 14 outputs tire pressure data, tire temperature data, tire acceleration data, and data including an ID code to the RF transmission circuit 16. The RF transmission circuit 16 modulates data from the sensor unit controller 14 to generate a modulation signal, and wirelessly transmits the modulation signal from the transmission antenna 19.

  For example, each tire sensor unit 3 periodically performs a tire state measurement operation at a first predetermined time interval (for example, every 1 to 15 seconds), while performing a data signal transmission operation at a first predetermined time interval. It is periodically performed at a second predetermined time interval (for example, 1 minute interval) longer than that. When the acceleration data of the acceleration sensor 13 exceeds a certain threshold, the transmission operation may be performed at an interval shorter than the second predetermined time interval. That is, the transmission operation may be performed by changing the second predetermined time interval between the running state and the stopped state of the vehicle 1. However, when the measured tire state 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.

  As shown in FIG. 1, the receiver unit 4 is installed at a predetermined location of the vehicle body, and operates by power from a battery (not shown) of the vehicle 1, for example. The receiver unit 4 includes a receiving antenna 32 disposed at an arbitrary position of the vehicle body, receives a data signal from each tire sensor unit 3 through the receiving antenna 32, and processes the received signal. In the present embodiment, the reception antenna 32 is disposed at a substantially intermediate position between the front wheel 2 and the rear wheel 2 in the front-rear direction of the vehicle 1.

  The receiver unit 4 includes a receiver unit controller 33 as a wheel position determination unit and an RF reception circuit 35 as a reception unit. 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 modulated signal received from each tire sensor unit 3 through the receiving antenna 32 and sends it to the receiver unit controller 33. The receiver unit controller 33 grasps the internal air pressure and the internal temperature of the tire 6 corresponding to the transmitting tire sensor unit 3 based on the data signal from the RF receiving circuit 35.

  Furthermore, the receiver unit controller 33 is based on the data signal from the RF receiving circuit 35, and is the transmission source tire sensor unit 3 provided on the left wheel 2 (FL, RL) of the vehicle 1? Then, it is determined whether the right wheel 2 (FR, RR) is provided.

  The receiver unit controller 33 causes the display 38 to display information on the internal air pressure and the internal 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.

  As shown in FIGS. 2 and 3, the strain sensor 20 provided on the substrate 21 of the tire sensor unit 3 has, for example, a metal resistor (metal foil) laid out in a zigzag shape on a thin insulator. The structure to be measured is used by being attached to the object to be measured, which is the substrate 21 in this embodiment. The strain sensor 20 detects that when the substrate 21 is deformed, the resistor has a reduced cross-sectional area due to elongation and is increased in length, and the resistance value of the resistor increases (piezoresistive effect). The distortion of the substrate 21 is detected. In the present embodiment, a single-axis strain sensor 20 having one element is used.

  The strain sensor 20 generates a data signal corresponding to the change in the resistance value and outputs it to the sensor unit controller 14. Since the change in resistance value is minute, a bridge circuit / amplifier circuit (not shown) is connected to the strain sensor 20 and is output as a data signal by these circuits.

  In the present embodiment, the strain sensor 20 is attached to the substrate 21 of the tire sensor unit 3, and the tire sensor unit 3 is attached to the wheel portion 5 to be provided on the wheel 2. Then, when the vehicle 1 starts acceleration, stops, or decelerates, stress is generated in the substrate 21 due to the acceleration / deceleration, and distortion occurs (deforms). Then, the strain sensor 20 attached to the substrate 21 detects the strain of the substrate 21 and outputs a data signal to the sensor unit controller 14.

  Specifically, for example, the strain sensor 20 provided on the front left side (FL) wheel 2 generates positive strain data in the direction opposite to the tangential acceleration direction of the wheel 2 when the vehicle 1 is accelerated, and accelerates when the vehicle 1 is decelerated. Conversely, negative strain data is output to the sensor unit controller 14. On the other hand, the front right side (FR) wheel 2 rotates in the opposite direction to the front left side (FL) wheel 2. For this reason, the strain sensor 20 provided on the front right wheel (FR) 2 has negative strain data opposite to the front left wheel (FL) when the vehicle 1 is accelerated, and the front side when the vehicle 1 is decelerated. In contrast to the left side (FL) wheel 2, positive strain data is output to the sensor unit controller 14, respectively. The same applies to the rear left wheel (RL) 2 and the rear right wheel (RR) 2.

Next, the operation of the tire condition monitoring device will be described.
When the vehicle 1 starts, when the wheels 2 start to rotate, the tire sensor units 3 provided on the front left side (FL) and front right side (FR) wheels 2 respectively rotate, and the centrifugal acceleration that has been zero until then is reduced. It is detected by each acceleration sensor 13. Each acceleration sensor 13 detects centrifugal acceleration and outputs a data signal reflecting tire acceleration data obtained by the detection to the sensor unit controller 14.

  Further, when the tire sensor unit 3 provided on the front left (FL) wheel 2 rotates and a stress is generated on the substrate 21, the left strain sensor 20 detects positive strain data and outputs it to the sensor unit controller 14. To do. On the other hand, when the tire sensor unit 3 provided on the wheel 2 on the front right side (FR) rotates and a stress is generated on the substrate 21, the strain sensor 20 on the right side detects negative strain data and outputs it to the sensor unit controller 14. To do. The sensor unit controller 14 transmits a data signal including tire acceleration data and strain data to the RF receiving circuit 35.

  The RF receiving circuit 35 demodulates the modulated signal received from each tire sensor unit 3 through the receiving antenna 32 and sends it to the receiver unit controller 33. Then, the receiver unit controller 33 determines that the vehicle 1 is in a starting state because the centrifugal acceleration is changing from zero based on the tire acceleration data. Further, the receiver unit controller 33 determines whether the data signals are data signals transmitted from the left tire sensor unit 3 based on the difference (positive or negative) in the polarity of the strain data, or the right tire sensor unit 3. It is determined whether the data signal is transmitted from. In the present embodiment, the tire sensor unit 3 that has transmitted positive strain data is located on the left side, and the tire sensor unit 3 that has transmitted negative strain data is located on the right side. Then, when the positions of the front left side (FL) wheel 2 and the front right side (FR) wheel 2 are specified, the receiver unit controller 33 determines the transmission source based on the data signal from each tire sensor unit 3. The tire internal pressure and the tire internal temperature of the tire 6 corresponding to the tire sensor unit 3 are grasped.

Similarly, the left and right positions of the rear left side (RL) wheel 2 and the rear right side (RR) wheel 2 are similarly determined.
According to the above embodiment, the following effects can be obtained.

  (1) The strain sensor 20 is provided on the substrate 21 of the tire sensor unit 3. When accelerating when the vehicle 1 starts, distortion occurs in the substrate 21 of the tire sensor unit 3 along with the acceleration. Since the rotation direction is opposite between the left side and the right side of the wheel 2, the data signal reflecting the distortion generated from the strain sensor 20 is reversed, and the tire sensor unit 3 to which the data signal is transmitted is on the left side. It is possible to determine whether the wheel 2 is provided on the right wheel 2 or the right wheel 2. And if the left-right position of the wheel 2 can be determined, the receiver unit controller 33 can grasp the state of each tire 6 based on the data signal from each tire sensor unit 3. Therefore, the receiver unit 4 can detect and grasp the state of the tire 6 without requiring a transmitter corresponding to each tire sensor unit 3, compared with the case where a transmitter is required. Thus, the tire condition monitoring device can be made inexpensive.

  (2) When the vehicle 1 travels at a constant speed, the strain detected by the left and right strain sensors 20 is substantially the same between the right wheel 2 and the left wheel 2, and the left and right positions of the wheels 2 are determined by the receiver unit controller 33. Difficult to judge. Here, the state of the vehicle when the value detected by the acceleration sensor 13 is changing from zero is not a constant speed running state but a starting state. For this reason, by using the acceleration sensor 13, it can be determined that the vehicle 1 is accelerating at the time of starting, and when the left wheel 2 and the right wheel 2 have different strain values, the wheel 2 Can be determined. As a result, it is possible to eliminate a useless determination process in which the receiver unit controller 33 becomes unable to determine the right and left positions of the wheels 2 during constant speed traveling.

  (3) The strain sensor 20 is added to the substrate 21 of the tire sensor unit 3, and the left / right position of the wheel 2 is determined based on the data signal from the strain sensor 20. Since the strain sensor 20 is inexpensive, it is possible to reduce the manufacturing cost of the tire sensor unit 3 by reducing the cost of parts added for determining the left and right positions of the wheels 2.

  (4) Since the single sensor type element having one element is employed as the strain sensor 20, it is possible to reduce the manufacturing cost of the tire sensor unit 3 by reducing the cost of components added for determining the left and right positions of the wheels 2.

  (5) For example, when the strain sensor 20 is provided in the wheel portion 5 of the wheel 2, it is necessary to connect the strain sensor 20 and the tire sensor unit 3 with a lead wire or the like, and the tire sensor unit 3 is increased in size. However, since the strain sensor 20 is attached to the substrate 21 of the tire sensor unit 3 and stored in the case 3a of the tire sensor unit 3, the left and right sides of the wheels 2 are not enlarged without increasing the size of the tire sensor unit 3. The position can be determined.

In addition, you may change the said embodiment as follows.
In the embodiment, when the acceleration data detected by the acceleration sensor 13 is changing from zero, it is determined that the vehicle 1 is starting, and the left and right positions of the wheels 2 are determined. Absent. For example, when the receiver unit controller 33 determines whether the vehicle 1 is in a stopped state when the centrifugal acceleration is changing to zero, and determines that the vehicle 1 is in a stopped state. The left and right positions of the wheel 2 may be determined based on the data signal of the strain sensor 20. Alternatively, the receiver unit controller 33 may determine the left and right positions of the wheels 2 during acceleration or deceleration while the vehicle 1 is traveling.

  In the embodiment, the strain sensor 20 employs a single-axis type having one element, but a two-axis type or a three-axis type in which two elements are arranged orthogonally or intersecting each other. It may be adopted.

  In the embodiment, the strain sensor 20 is attached to the substrate 21 of the tire sensor unit 3, but the strain sensor 20 may be attached to the case 3a (measurement object) of the tire sensor unit 3.

  In the embodiment, the left and right positions of the wheel 2 are determined using the strain sensor 20. However, the tire sensor unit 3 is attached to the wheel unit 5 in the wheel 2 using the detection data of the strain sensor 20. The presence or absence of damage to the substrate 21 may be detected.

(Circle) this invention is not limited to application to a tire condition monitoring apparatus, It can apply to the various apparatuses which determine the position 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 strain sensor is a single-axis type element having one element. The wheel position determination device according to any one of claims 1 to 3.
(B) Each of the wheel side units is a tire sensor unit that detects a state of the tire in the wheel and wirelessly transmits a data signal including data indicating the detected state of the tire. The wheel position determination device according to any one of the technical ideas (A).

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Wheel, 3 ... Tire sensor unit (wheel side unit), 4 ... Receiver unit, 13 ... Acceleration sensor, 16 ... RF transmission circuit (transmission part), 20 ... Strain sensor, 21 ... Substrate (cover Measurement object), 32... Reception antenna, 33... Receiver unit controller (wheel position determination unit), 35... RF reception circuit (reception unit).

Claims (3)

A wheel position determination device for determining the position 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 the vehicle body of the vehicle,
Each wheel side unit detects a strain of the object to be measured accompanying acceleration or deceleration of the vehicle, and generates a data signal corresponding to the strain,
A transmitter that wirelessly transmits the data signal;
The receiver unit receives a data signal transmitted from each wheel side unit through a receiving antenna; and
Whether the data signal is a data signal transmitted from the wheel-side unit provided on the left wheel of the vehicle based on information on the strain included in the received data signal, or the wheel provided on the right wheel A wheel position determination unit that determines whether the data signal is transmitted from the side unit.   Each wheel side unit includes an acceleration sensor that rotates together with the wheel and generates a data signal reflecting centrifugal acceleration, and the wheel position determination unit is triggered by the fact that the centrifugal acceleration is changing from zero. It is determined whether the vehicle is in a starting state or whether the vehicle is in a stopping state when the centrifugal acceleration is changing to zero, and the vehicle is in the starting state or the stopping state. The wheel position determination device according to claim 1, wherein when it is determined that the vehicle is in a state, the left and right positions of the wheel are determined based on the data signal of the strain sensor.   The wheel position determination device according to claim 1, wherein the object to be measured is a substrate of the wheel side unit.

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