JP2014231338A - Wheel position specification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel position specification device capable of easily specifying a longitudinal position of a wheel side unit by using acceleration.SOLUTION: A wheel side units 3 make an RF transmission circuit transmit an RF signal when acceleration of gravity which is detected when a wheel 2 travels on an obstacle exceeds a preset threshold value. A receiver unit controller 33 of a receiver unit 4 specifies a position of the wheel side unit 3 which transmitted the RF signal earlier as a front side position and specifies a position of the wheel side unit 3 which transmitted the RF signal later as a rear side position if it receives the RF signals twice with an interval.

Description

  The present invention relates to a wheel position specifying device for specifying front and rear 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. Generally, the tire condition monitoring device includes a plurality of wheel side units that are respectively mounted on the wheels of the vehicle, and a receiver unit that is mounted on the vehicle body of the vehicle. Each wheel unit detects the state of the corresponding tire, that is, the pressure and temperature in the tire, and wirelessly transmits a signal including data indicating the detected tire state through the transmission antenna.

  On the other hand, the receiver unit receives a signal from each wheel side unit, 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 tires the received signal is transmitted from the wheel side unit provided in the tire, in other words, the wheel related to the received signal. The position is specified in the receiver unit.

  An example of the position specifying method is Patent Document 1. In Patent Document 1, vibration generated in each wheel during traveling is detected by an acceleration sensor, and an air pressure inside the tire when the vibration is generated is detected by an air pressure sensor provided inside the tire. The correlation calculation unit calculates the correlation between the vibration information detected by the acceleration sensor and the air pressure information detected by the air pressure sensor. Based on the obtained correlation, the position of the air pressure sensor that outputs the air pressure information, that is, the wheel Identify the location.

JP 2007-139701 A

  However, in the configuration in which the position is specified using the vibration (acceleration) generated in the wheel, the air pressure information must be correlated with the vibration information by the correlation calculation unit, and the position specification is troublesome.

  An object of the present invention is to provide a wheel position specifying device that can easily specify the front-rear position of a wheel-side unit using acceleration.

  In order to solve the above problem, the wheel position specifying device according to claim 1 is a wheel position specifying device for specifying front and rear positions of a plurality of wheels provided in a vehicle, and is provided in each of the wheels. And a receiver unit installed on the vehicle body of the vehicle, the wheel side unit rotating with the wheel and detecting an acceleration, and a signal including the acceleration detected by the acceleration sensor The receiver unit is equipped with a receiver for signals transmitted from each wheel side unit, and the signal is transmitted from any of the front and rear wheel units. A wheel position specifying unit for specifying whether or not the wheel side unit is preset with the acceleration detected when the wheel travels on an obstacle. When the signal exceeds the threshold value, the transmission unit transmits the signal, and when the wheel position specifying unit receives the signal twice at intervals, the position of the wheel side unit that transmitted the signal first is defined as the front side. The gist is to identify the position of the wheel side unit that has been identified and later transmitted the signal as the rear side.

  According to this, when the wheel travels on the obstacle, the acceleration detected by the acceleration sensor greatly changes from the acceleration detected when the wheel does not travel on the obstacle. And when the acceleration which changed greatly exceeds a threshold value, a transmission part transmits a signal. For example, when the vehicle travels straight and the front wheel passes over the obstacle, the rear wheel also passes over the same obstacle immediately after that. Therefore, the two front and rear wheel side units transmit signals including the same value of acceleration at intervals. When the wheel position specifying unit receives two signals including acceleration of the same value, the wheel side unit that transmitted the signal first is provided on the front wheel, and the wheel side unit that transmitted the signal later It can be easily identified as being provided on the rear wheel.

  Further, in the wheel position specifying device, the wheel position specifying unit divides the wheel base of the vehicle by the vehicle speed, and the rear wheel side unit passes through the obstacle and the rear wheel side unit moves to the obstacle. Calculate the time taken to pass over the obstacle, calculate the time taken to receive the signal from the timing when the signal was received first, and compare and send the two calculated times It is preferable to determine whether or not the two received signals have been transmitted when passing over the obstacle.

  According to this, if the calculated two times are the same, it can be determined that the two received signals are signals transmitted when the front and rear wheels pass over the same obstacle. Therefore, it is possible to avoid erroneously specifying the front and rear positions.

In the wheel position specifying device, the wheel side unit includes a state detection unit that detects a state of the wheel, and the signal includes a detection result of the state detection unit.
According to this, the state of the wheel can be grasped simultaneously with the specification of the front and rear position of the wheel.

  According to the present invention, the front-rear position of the wheel-side unit can be easily specified using the acceleration.

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 wheel side unit. (A) is a graph showing the relationship between the acceleration detected on the front left wheel and the number of measurements, and (b) is a graph showing the relationship between the acceleration detected on the rear left wheel and the number of measurements.

  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 wheel-side 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. 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. In the vehicle 1, the distance in the front-rear direction between the axis of the front wheel 2 and the axis of the rear wheel 2 is used as the wheel base.

  Each wheel side 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 wheel side unit 3 detects the state of the corresponding tire 6 (in-tire pressure, in-tire temperature) and the like, and wirelessly transmits a signal including data indicating the detected tire state.

  As shown in FIG. 2, each wheel side 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. The wheel side 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 rotates with the rotation of the wheel 2 and is known as a piezoresistive type or electrostatic capacitance type acceleration sensor, for example, and generates and outputs a data signal corresponding to the gravitational acceleration. As the acceleration sensor 13, an acceleration sensor capable of detecting a gravitational acceleration component in a direction along one detection axis along the circumferential direction of the wheel 2 is used.

  As shown in FIGS. 3 (a) and 3 (b), when the vehicle 1 is traveling, the wheel 2 does not pass over the obstacles A and B, but is traveling on a flat surface, the acceleration sensor 13 is Theoretically, the gravitational acceleration is detected within a range of plus or minus 1G. On the other hand, when the wheel 2 rides on the obstacle A (convex part), the acceleration sensor 13 detects the gravitational acceleration exceeding the plus 1G in the plus direction, and when the wheel 2 gets in the obstacle B (concave part), The acceleration sensor 13 detects a gravitational acceleration exceeding minus 1G in the minus direction. The acceleration sensor 13 outputs gravity acceleration data obtained by the detection to the sensor unit controller 14.

  As shown in FIG. 2, the sensor unit controller 14 includes a microcomputer including a CPU and a storage unit 14a (RAM, ROM, etc.), and the storage unit 14a has an ID as identification information unique to each wheel side unit 3. The code is registered. This ID code is information used to identify each wheel side unit 3 in the receiver unit 4. As shown in FIG. 1, in the present embodiment, the ID code of the wheel side unit 3 of the front left side FL is ID1, the ID code of the wheel side unit 3 of the front right FR is ID2, and the wheel side 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 gravity acceleration data to the RF transmission circuit 16. An RF transmission circuit 16 as a transmission unit modulates each data to generate an RF signal, and wirelessly transmits the RF signal from the transmission antenna 18.

  The storage unit 14a of the sensor unit controller 14 stores an overall program for comprehensively controlling the operation of the wheel side unit 3. In addition, a threshold for comparison with the gravitational acceleration detected by the acceleration sensor 13 is stored in the storage unit 14a in advance.

  As shown in FIGS. 3 (a) and 3 (b), the threshold value is a positive threshold value A that is compared with the gravitational acceleration detected when the wheel 2 rides on the obstacle A (convex portion), and The threshold B on the negative side compared with the gravitational acceleration detected when the obstacle B (concave portion) is filled, and is obtained in advance by experiments or the like. The threshold value A on the plus side is a value (for example, plus 2G) that is set larger with a margin than plus 1G, and the threshold value B on the minus side is set smaller with a margin than minus 1G. Value (for example, minus 2G). Then, when the gravitational acceleration detected by the acceleration sensor 13 exceeds the thresholds A and B, the sensor unit controller 14 modulates the detected gravitational acceleration data with the RF transmission circuit 16 to generate an RF signal, The generated RF signal is transmitted from the RF transmission circuit 16.

  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 a program for comprehensively controlling the operation of the receiver unit 4 is stored in the storage unit. Furthermore, data related to vehicle speed is input to the receiver unit controller 33 of the receiver unit 4 from a vehicle speed sensor (not shown). Further, the wheel base of the vehicle 1 is stored in advance in the storage unit. The RF receiving circuit 35 demodulates the RF signal received from each wheel side unit 3 through the RF receiving antenna 32 and sends the demodulated signal 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 tire temperature of the tire 6 corresponding to the wheel side unit 3 that is the transmission source. 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.

  The receiver unit controller 33 specifies the front and rear positions of the wheels 2 based on the program. Therefore, in this embodiment, the receiver unit controller 33 corresponds to a wheel position specifying unit. When the position is specified, the receiver unit controller 33 uses the gravitational acceleration included in the RF signal output from the RF receiver circuit 35 so that the transmission-side wheel-side unit 3 is provided on any wheel 2 before or after the vehicle 1. It is specified whether it is what was done. When specifying the position, the receiver unit controller 33 divides the wheel base of the vehicle 1 of the wheel 2 by the vehicle speed, and after the front wheel 2 passes over the obstacle, the rear wheel 2 becomes the obstacle. The time taken to pass above (passing time t1) is calculated. Further, when the position is specified, when the receiver unit controller 33 receives the RF signal twice at intervals, the time (elapsed time t2) required from the timing when the RF signal is received first to the time when the RF signal is received later is received. ) Is calculated.

  Next, a method for specifying the front and rear positions of the wheels will be described with reference to FIG. A case where the position of the wheel 2 on the front left side FL and the position of the wheel 2 on the rear left side RL is specified will be described.

  As shown in FIG. 3 (a), when the wheel 2 on the front left side FL rides on the obstacle A while the vehicle 1 is traveling, the acceleration sensor 13 in the wheel side unit 3 on the front left side FL moves plus 1G in the plus direction. Detect the gravitational acceleration that exceeded. Then, the gravitational acceleration data detected by the acceleration sensor 13 is output to the sensor unit controller 14, and the sensor unit controller 14 compares the detected gravitational acceleration with a positive threshold A. When the detected gravitational acceleration exceeds the threshold value A, the sensor unit controller 14 sends an RF signal including tire information, gravitational acceleration, and ID code detected when the vehicle gets on the obstacle A from the RF transmission circuit 16. Send it.

Subsequently, the wheel 2 of the rear left RL rides on the obstacle A with a certain interval.
Then, as shown in FIG.3 (b), in the wheel side unit 3 of the rear left side RL, the acceleration sensor 13 detects the gravitational acceleration exceeding plus 1G in the plus direction. Then, the gravitational acceleration data detected by the acceleration sensor 13 is output to the sensor unit controller 14, and the sensor unit controller 14 compares the detected gravitational acceleration with the threshold A on the plus side. If the detected gravitational acceleration exceeds the threshold A, the sensor unit controller 14 transmits an RF signal including tire information, gravitational acceleration, and ID code detected when the vehicle gets on the obstacle A to the RF transmission circuit. 16 is transmitted.

  In the receiver unit 4, the RF signal transmitted by the wheel side unit 3 of the front left side FL and the RF signal transmitted by the wheel side unit 3 of the rear left side RL are transmitted through the RF receiving antenna 32 at a certain interval. Received by the receiving circuit 35. The RF signal received by the RF receiving circuit 35 is output to the receiver unit controller 33. The receiver unit controller 33 calculates the elapsed time t2 from the two reception timings.

  The receiver unit controller 33 calculates the passing time t1 using the wheel base of the vehicle 1 and the vehicle speed. Then, the receiver unit controller 33 compares the calculated elapsed time t2 with the passage time t1. If it is determined that they match, the receiver unit controller 33 determines that the two transmitted RF signals are transmitted when they pass over the same obstacle A. Conversely, when the elapsed time t2 and the passage time t1 do not match, the receiver unit controller 33 does not specify the front-rear position of the wheel 2.

  Thereafter, the receiver unit controller 33 determines that the wheel-side unit 3 that has transmitted the RF signal earlier is that of ID1 provided on the front wheel 2, and later transmits the wheel-side unit 3 that has transmitted the RF signal to the rear side. It determines with the thing of ID3 provided in the wheel 2 of the side. Therefore, the front / rear position of the wheel 2 is specified by the receiver unit controller 33.

  Similarly, as shown in FIGS. 3 (a) and 3 (b), when the wheel 2 on the front left side FL is obstructed by the obstacle B during traveling of the vehicle 1, in the wheel side unit 3 on the front left side FL, The acceleration sensor 13 detects gravitational acceleration exceeding minus 1G in the minus direction. Further, in the wheel side unit 3 on the rear left side RL with a certain interval, the acceleration sensor 13 detects gravitational acceleration exceeding minus 1G in the minus direction. Then, the sensor unit controller 14 compares the detected gravitational acceleration with a negative threshold B. If the detected gravitational acceleration exceeds the threshold value B, the sensor unit controller 14 transmits an RF signal including tire information, gravitational acceleration, and an ID code detected when the obstacle B is covered with the RF transmission circuit 16. To send from.

  In the receiver unit 4, the receiver unit controller 33 calculates the passage time t1 and the elapsed time t2 in the same manner as described above, and compares the calculated elapsed time t2 with the passage time t1. And when it determines with it agree | coinciding, the receiver unit controller 33 determined the wheel side unit 3 which transmitted RF signal previously as that of ID1 provided in the front wheel 2, and transmitted RF signal later. The wheel side unit 3 is determined to be that of ID3 provided on the rear wheel 2. Therefore, the front / rear position of the wheel 2 is specified by the receiver unit controller 33.

According to the above embodiment, the following effects can be obtained.
(1) While the vehicle 1 is traveling, the front and rear wheels 2 pass on the same obstacles A and B on one side of the vehicle 1 in the left-right direction. For this reason, the same gravitational acceleration is detected at the front and rear wheels 2, and the receiver unit controller 33 of the receiver unit 4 receives the RF signal including the same gravitational acceleration twice. The receiver unit controller 33 can identify the wheel side unit 3 that has transmitted the RF signal first as the front side and the wheel side unit 3 that has transmitted the RF signal later as the rear side. Therefore, the front-rear position of the wheel 2 can be easily specified only by detecting the event that the rear wheel 2 passes behind the obstacles A and B with a delay from the front wheel 2 by the acceleration sensor 13. .

  (2) The receiver unit controller 33 calculates the passage time t1 from the wheel base and the vehicle speed, and calculates the elapsed time t2 from the reception timing of the RF signal. Then, the receiver unit controller 33 compares the elapsed time t2 with the passage time t1, and determines whether or not the two transmitted RF signals are transmitted when the obstacles A and B are passed. judge. For this reason, it can avoid that specification of the front-back position of the wheel 2 is performed accidentally.

  (3) When the gravitational acceleration exceeds the threshold values A and B, the wheel side unit 3 transmits an RF signal including tire pressure data and tire temperature data to the receiver unit 4 in addition to the gravitational acceleration. Therefore, the receiver unit controller 33 can specify the front-rear position of the wheel 2 and display the tire information of the specified wheel 2 on the display 38.

  (4) The acceleration sensor 13 having one detection axis along the circumferential direction of the wheel 2 was used. Therefore, the acceleration sensor 13 can detect the gravitational acceleration excluding the centrifugal acceleration, and can accurately detect the gravitational acceleration when the wheel 2 passes over the obstacles A and B.

  (5) The receiver unit controller 33 calculates the passage time t1 from the wheel base and the vehicle speed, and calculates the elapsed time t2 from the reception timing. Therefore, time comparison for avoiding erroneous specification of the front and rear positions of the wheel 2 can be performed by the receiver unit controller 33, and the burden on the wheel side unit 3 can be reduced.

In addition, you may change this embodiment as follows.
In the embodiment, the acceleration sensor 13 having one detection axis along the circumferential direction of the wheel 2 is used. Not only this but what has a detection axis along the diameter direction of wheel 2 may be used. In this case, since the obtained gravitational acceleration changes according to the vehicle speed, the threshold when traveling on the obstacle is in the range of plus or minus of the gravitational acceleration according to the vehicle speed, and the detected gravitational acceleration is within the above range. Is exceeded, the wheel side unit 3 transmits an RF signal.

  In the embodiment, the wheel side unit 3 transmits the RF signal when the gravitational acceleration exceeds the thresholds A and B. However, the threshold may be changed as appropriate. For example, the difference between the plus or minus gravity acceleration when passing over an obstacle and the maximum value (plus 1G or minus 1G) of plus or minus when not passing over the obstacle is a predetermined value. When (threshold) is exceeded, the wheel side unit 3 may transmit an RF signal.

○ When the RF signal is transmitted when the gravitational acceleration exceeds the threshold value, the tire pressure data and the tire temperature data may not be included in the RF signal.
When the position is specified, the elapsed time t2 is compared with the passage time t1, and it is determined whether or not the two transmitted RF signals are transmitted when the obstacles A and B are transmitted. This determination may not be performed.

(Circle) It is not limited to application to the wheel position specific device for four-wheeled vehicles 1, You may apply to the wheel position specific device for two-wheeled vehicles.
The transmission unit of the wheel side unit 3 may be a low-frequency transmission circuit instead of the RF transmission circuit 16.

The receiving unit of the receiver unit 4 may be a low-frequency receiving circuit instead of the RF receiving circuit 35.
The wheel position specifying device is not limited to the application to the tire condition monitoring device, and can be applied to various devices that monitor the state of the wheel 2.

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 in which the state detection unit is a pressure sensor and a temperature sensor.
(B) The acceleration sensor is a wheel position specifying device including a detection axis along a circumferential direction of the wheel.

  A, B ... Obstacle, 1 ... Vehicle, 2 ... Wheel, 3 ... Wheel side unit, 4 ... Receiver unit, 11 ... Pressure sensor as state detector, 12 ... Temperature sensor as state detector, 13 ... Acceleration Sensor, 16 ... RF transmission circuit as transmission unit, 33 ... Receiver unit controller as wheel position specifying unit, 35 ... RF reception circuit as reception unit.

Claims (3)

A wheel position specifying device for specifying front and rear 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 the vehicle body of the vehicle,
The wheel side unit has an acceleration sensor that rotates together with the wheel and detects acceleration, and a transmission unit that can wirelessly transmit a signal including the acceleration detected by the acceleration sensor,
The receiver unit includes a receiving unit for signals transmitted from each wheel side unit, and a wheel position specifying unit for specifying whether the signal is transmitted from either the front or rear wheel side unit. ,
The wheel side unit causes the transmission unit to transmit the signal when the acceleration detected when the wheel travels on an obstacle exceeds a preset threshold,
When the wheel position specifying unit receives the signal twice with an interval, the wheel position specifying unit specifies the position of the wheel side unit that has transmitted the signal first as the front side, and later determines the position of the wheel side unit that has transmitted the signal. A wheel position specifying device characterized by specifying a side.   The wheel position specifying unit divides the wheel base of the vehicle by the vehicle speed until the rear wheel side unit passes over the obstacle after the front wheel side unit passes over the obstacle. Calculate the time taken, calculate the time taken from the timing of receiving the signal first to the time of receiving the signal later, and compare the two calculated times to determine whether the two signals transmitted The wheel position specifying device according to claim 1, wherein it is determined whether or not it is transmitted when passing over an object.   The wheel position specifying device according to claim 1, wherein the wheel side unit includes a state detection unit that detects a state of the wheel, and the signal includes a detection result of the state detection unit.