JPWO2013133309A1 - Tire pressure monitoring device - Google Patents

Abstract

The rotational position of each wheel when a wireless signal including certain identification information is transmitted is acquired at a plurality of different centrifugal accelerations and stored as rotational position data of each wheel. The rotational direction of each rotational position of each rotational position data Approximate lines are calculated from the distribution of rotational positions with respect to acceleration, and the left and right positions of the transmitter corresponding to the identification information are determined based on the approximate line shape of the rotational position data with the smallest degree of variation of each rotational position with respect to the approximate line. To do.

Description

  The present invention relates to a tire pressure monitoring device.

  In Patent Document 1, acceleration detection means for detecting rotational direction acceleration and acceleration detection means for detecting centrifugal direction acceleration are provided on a wheel, and the wheel is attached to a tire based on the direction of phase shift of output waveforms of the two acceleration detection means. A technique for determining the left and right position of a tire pressure sensor is disclosed.

JP 2006-205906 A

However, the above-described prior art has a problem in that the cost is increased because two acceleration detecting means are required for each wheel.
An object of the present invention is to provide a tire air pressure monitoring device capable of determining the left and right position of a transmitter with one acceleration detecting means for each wheel.

  In order to achieve the above-described object, in the present invention, the rotational position of each wheel when a radio signal including certain identification information is transmitted is acquired at a plurality of different centrifugal accelerations and stored as rotational position data of each wheel. The approximate line is calculated from the distribution of the rotational position with respect to the centrifugal acceleration at each rotational position of each rotational position data, and based on the shape of the approximate line of the rotational position data with the smallest degree of variation of each rotational position with respect to the approximate line. The left and right positions of the transmitter corresponding to the identification information are determined.

  Therefore, in the present invention, the left and right positions of the transmitter can be determined by one acceleration detection means for each wheel.

1 is a configuration diagram of a tire air pressure monitoring device of Example 1. FIG. It is sectional drawing which shows the attachment position in the tire of the TPMS sensor 2 of Example 1. FIG. 1 is a perspective view showing a configuration of a TPMS sensor 2 of Example 1. FIG. It is a control block diagram of TPMSCU4 for carrying out left-right position determination control. 3 is a diagram showing a method for calculating the rotational position of each wheel 1. FIG. 5 is a flowchart showing a flow of a left / right position determination control process by a left / right position determination unit 12. It is a figure showing the difference in the TPMS data transmission timing of the TPMS sensor 2 of the right front wheel (or right rear wheel 1RR) by the difference in vehicle speed. It is a change characteristic figure of rotation position data to vehicle speed.

1 Each wheel
2 TPMS sensor
2a Pressure sensor (Tire pressure detection means)
2b G sensor (acceleration detection means)
2c Sensor CU
2d transmitter
2e button battery
2f Temperature sensor
2g board
3a receiver
3b receiver
5a display
5b Warning lamp
6 ABSCU
7 Communication line
8 Wheel speed sensor
9 memory
10a Front position detector
10b Rear position determination unit
11 Rotation position calculation unit (Rotation position detection means)
12 Map generator
13 Left / right position determination unit (left / right position determination means)
15 Vehicle speed sensor (vehicle speed detection means)
20 Air valve
21 tires
22 foil rim
23 Valve hole
24 Main unit
24a center
24b right side
24c Left side
25 well
26 Rubber part (elastic body)
27 cases
28 faces

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described using embodiments based on the drawings.
[Example 1]
FIG. 1 is a configuration diagram of a tire pressure monitoring apparatus according to the first embodiment. In the figure, FL at the end of each symbol indicates a left front wheel, FR indicates a right front wheel, RL indicates a left rear wheel, and RR indicates a right rear wheel. In the following description, the description of FL, FR, RL, and RR is omitted when there is no need to explain them individually.
The tire pressure monitoring apparatus of the first embodiment includes a TPMS (Tire Pressure Monitoring System) sensor 2, receivers 3a and 3b, a TPMS control unit (TPMSCU) 4, a display 5a, a warning lamp 5b, and a wheel speed sensor 8. And a vehicle speed sensor (vehicle speed detection means) 15. The TPMS sensor 2 is attached to each wheel 1, and the receivers 3a and 3b, the TPMSCU 4, the display 5a, the warning lamp 5b, the wheel speed sensor 8 and the vehicle speed sensor 15 are provided on the vehicle body side.

FIG. 2 is a cross-sectional view showing the mounting position of the TPMS sensor 2 of the first embodiment in the tire, and FIG. 3 is a perspective view showing the configuration of the TPMS sensor 2 of the first embodiment.
The TPMS sensor 2 includes an air valve 20 and a main body 24 attached to one end of the air valve 20. The air valve 20 is a snap-in type air valve in which a rubber part (elastic body) 26 covering the outer periphery is fixed to the valve hole 23 of the wheel rim 22. The main body 24 is attached to the end of the air valve 20 on the side located in the tire 21. Therefore, the main body portion 24 is located outside the well 25 of the wheel rim 22 in the tire radial direction in the tire 21. The main body 24 is attached so as to be horizontal with respect to the ground when the tire 21 rotates and the valve hole 23 is at the uppermost point.
In the main body 24, a substrate 2g and a button battery 2e are stored inside a resin case 27. The main body 24 extends in a direction perpendicular to the axial direction of the air valve 20, the substrate 2g is disposed from the central portion 24a to the right side 24b of the main body 24, and the button battery 2e is disposed on the left side 24c of the main body 24. ing.
A pressure sensor (tire pressure detecting means) 2a, a G sensor (acceleration detecting means) 2b, a temperature sensor 2f, a sensor control unit (sensor CU) 2c, and a transmitter 2d are mounted on the board 2g.
The pressure sensor 2a detects tire air pressure [kPa].
The G sensor 2b detects centrifugal acceleration [G] acting on the tire.
The temperature sensor 2f detects the temperature [° C.] in the tire.
The sensor CU2c operates by the electric power from the button battery 2e, and transmits TPMS data including at least the tire pressure information detected by the pressure sensor 2a and the sensor ID (identification information) from the transmitter 2d by a radio signal. In the first embodiment, the sensor ID is 1 to 4.
Since the button battery 2e is heavier than the substrate 2g, the center of gravity in the longitudinal direction of the main body 24 is located closer to the button battery 2e than the surface 28 including the tire rotation shaft and the valve hole 23.

The sensor CU2c compares the centrifugal acceleration detected by the G sensor 2b with a preset traveling determination threshold value, and determines that the vehicle is stopped if the centrifugal acceleration is less than the traveling determination threshold value, and determines TPMS data. Stop sending On the other hand, if the centrifugal acceleration is equal to or greater than the travel determination threshold, it is determined that the vehicle is traveling, and TPMS data is transmitted at a predetermined timing. Sensor CU2c also sends a motion flag ON signal that informs TPMSCU4 of the start of wireless signal transmission when the centrifugal acceleration reaches or exceeds the travel determination threshold, and the centrifugal acceleration is determined to be the travel determination threshold. When the value falls below, a motion flag OFF signal is sent once to notify the TPMSCU4 of the end of wireless signal transmission.
The receivers 3a and 3b receive the radio signal output from each TPMS sensor 2 and output it to the TPMSCU 4. Here, the receiver 3a is disposed on the front side of the vehicle and between the left and right front wheels 1FL and 1FR, and the receiver 3b is disposed on the rear side of the vehicle and between the left and right rear wheels 1RL and 1RR. Yes.

  The TPMSCU4 reads each TPMS data, refers to the correspondence between each sensor ID and each wheel position stored in the nonvolatile memory 9 (see FIG. 4) from the sensor ID of the TPMS data, and which wheel the TPMS data has It is determined whether it corresponds to the position, and the tire air pressure included in the TPMS data is displayed on the display 5a as the air pressure at the corresponding wheel position. Further, when the tire air pressure falls below a lower limit value (for example, 80% of the recommended pressure), the driver is warned of a decrease in tire air pressure by changing the display color, blinking display, lighting of the warning lamp 5b, or blinking.

ABSCU 6 detects the wheel speed of each wheel 1 based on the wheel speed pulse from each wheel speed sensor 8, and when a certain wheel tends to lock, it activates the ABS actuator (not shown) to turn the wheel cylinder of that wheel. Implement anti-skid brake control that suppresses the tendency to lock by increasing or decreasing the pressure. The ABSCU 6 outputs the count value of the wheel speed pulse to the CAN communication line 7 at a predetermined cycle (for example, 20 msec).
Each wheel speed sensor 8 is a pulse generator that generates a predetermined number z (for example, z = 48) of wheel speed pulses for one rotation of the wheel 1, a gear-shaped rotor that rotates in synchronization with the wheel 1, It is composed of a permanent magnet and a coil which are disposed on the vehicle body side and are opposed to the outer periphery of the rotor. When the rotor rotates, the uneven surface of the rotor crosses the magnetic field formed around the wheel speed sensor 8 to change its magnetic flux density, generating an electromotive force in the coil, and this voltage change is applied to the ABSCU 6 as a wheel speed pulse signal. Output.

As described above, since the TPMSCU 4 determines which wheel data the received TPMS data is based on the correspondence between each sensor ID stored in the memory 9 and each wheel position, the vehicle is stopped. When the tire rotation is performed, the correspondence between each sensor ID and each wheel position stored in the memory 9 does not match the actual correspondence, and it is impossible to know which wheel data the TPMS data is. Here, “tire rotation” refers to changing the mounting position of the tire in order to make the tire tread wear uniform and extend the life (tread life). For example, in a passenger car, the left and right tire positions are generally crossed to replace the front and rear wheels.
Therefore, in Example 1, in order to register the correspondence between each sensor ID and each wheel position after tire rotation by storing and updating in the memory 9, there is a possibility that tire rotation has been performed. The TPMS data transmission cycle is changed on the 2nd side, and the TPMSCU4 side determines which wheel each TPMS sensor 2 belongs to based on the TPMS data radio wave intensity, the TPMS data transmission cycle, each wheel speed pulse, and the vehicle speed. To do.

[Position transmission mode]
The sensor CU2c of the TPMS sensor 2 determines that there is a possibility that tire rotation has been performed when the vehicle stop determination time immediately before the start of traveling is a predetermined time (for example, 15 minutes) or more.
When the vehicle stop determination time immediately before the start of traveling is less than the predetermined time, the sensor CU2c performs the “normal mode” in which TPMS data is transmitted at regular intervals (for example, 1 minute intervals). On the other hand, when the vehicle stop determination time is equal to or longer than the predetermined time, it is an interval shorter than the transmission interval in the normal mode (for example, about 16 seconds interval), and transmits TPMS data at a constant rotational position. Is implemented.
The fixed position transmission mode is carried out until the number of transmissions of TPMS data reaches a predetermined number (for example, 40 times), and when the number of transmissions reaches a predetermined number, the mode shifts to the normal mode. If it is determined that the vehicle has stopped before the number of transmissions of TPMS data reaches the predetermined number, if the vehicle stop determination time is less than the predetermined time (15 minutes), the fixed position transmission before the vehicle stops until the number of transmissions reaches the predetermined number The mode is continued, and when the vehicle stop determination time is a predetermined time or longer, the continuation of the fixed position transmission mode before the vehicle is stopped is canceled and the fixed position transmission mode is newly started.

  The sensor CU2c determines the transmission timing of the TPMS data in the fixed position transmission mode based on the gravitational acceleration dependent component of the centrifugal acceleration detected by the G sensor 2b during the fixed position transmission mode. The centrifugal acceleration acting on the TPMS sensor 2 changes with the acceleration / deceleration of the wheel 1, but its gravitational acceleration dependent component is always constant, +1 [G] at the highest point and -1 [G] at the lowest point The waveform which is 0 [G] at a position of 90 degrees with respect to the uppermost point and the lowermost point is shown. That is, the rotational position of the TPMS sensor 2 can be grasped by monitoring the magnitude and direction of the gravitational acceleration component of the centrifugal acceleration. Therefore, for example, by outputting TPMS data at the peak of the gravity acceleration dependent component, TPMS data can always be output at the highest point.

[Auto learning mode]
The TPMSCU 4 determines that the tire rotation may have been performed when the elapsed time from the ignition switch OFF to the ON is equal to or longer than a predetermined time (for example, 15 minutes).
TPMSCU4 monitors the tire air pressure of each wheel 1 based on the air pressure information of TPMS data transmitted from each TPMS sensor 2 when the elapsed time from the ignition switch OFF to ON is less than the predetermined time. Is implemented. On the other hand, when the elapsed time from the ignition switch to the ON is equal to or longer than a predetermined time, the “auto-learning mode” for determining the wheel position of each TPMS sensor 2 is performed. The auto-learning mode is executed until the wheel positions of all the TPMS sensors 2 are determined. When the wheel positions of all the TPMS sensors 2 are determined, the monitor mode is entered.
Note that even during the auto-learning mode, the tire pressure can be monitored from the air pressure information included in the TPMS data. Therefore, during the auto-learning mode, each sensor ID and each wheel position currently stored in the memory 9 can be monitored. Air pressure display and warning of air pressure drop based on the corresponding relationship.

[Left / right position determination control]
FIG. 4 is a control block diagram of the TPMSCU 4 for performing the left / right position determination control. The TPMSCU 4 includes a front position determination unit 10a, a rear position determination unit 10b, a rotation position calculation unit (rotation position detection means) 11, and a left / right position. A determination unit (left / right position determination means) 12 is provided.
The front position determination unit 10a determines that the TPMS data output from the receiver 3a whose radio field intensity is greater than or equal to the threshold is TPMS data from the TPMS sensor 2 mounted on either the left or right front wheel 1FL or 1FR. And output to the rotational position calculation unit 11 as TPMS data of the front wheels.
The rear position determination unit 10b is the TPMS data from the TPMS sensor 2 mounted on either the left or right rear wheel 1RL or 1RR of the TPMS data output from the receiver 3b whose radio wave intensity is greater than or equal to the threshold value. This is determined and output to the rotational position calculation unit 11 as TPMS data for the rear wheels.
That is, since the receiver 3a is disposed on the front side of the vehicle and the receiver 3b is disposed on the rear side of the vehicle, the radio field intensity of the radio signal output from the near transmitter 2d is output from the distant transmitter 2d. For example, if the radio field strength of the TPMS data received by the receiver 3a is equal to or greater than the threshold, the TPMS data is transmitted from the transmitter 2d of the left and right front wheels 1FL, 1FR. It can be determined that the data is TPMS data. Similarly, when the radio field intensity of the TPMS data received by the receiver 3b is equal to or greater than the threshold, it can be determined that the TPMS data is TPMS data transmitted from the transmitter 2d of the left and right rear wheels 1RL and 1RR.

The rotational position calculation unit 11 inputs each TPMS data output from the front position determination unit 10a and the rear position determination unit 10b and the count value of each wheel speed pulse output from the ABSCU 6 to the CAN communication line 7, and outputs each TPMS. The rotational position (number of teeth of the rotor) of each wheel 1 when the rotational position of the sensor 2 reaches the highest point is calculated. Here, “the number of teeth of the rotor” indicates which number of teeth of the rotor is counted by the wheel speed sensor 8, and the count value of the wheel speed pulse is a count value for one rotation of the tire (= 1 rotation). The number of teeth z = 48) can be obtained by division. The rotation position calculation unit 11 is based on the value obtained by adding 1 to the remainder of dividing the count value by the number of teeth for one rotation when the count value of each wheel speed pulse is input for the first time after starting the auto-learning mode. The number of teeth is determined based on the number of wheel speed pulses counted from the reference number of teeth (current count value minus the first count value) from the second time onward.
When the TPMS data is input, the rotational position calculation unit 11 inputs the vehicle speed detected by the vehicle speed sensor 15 at the same time, and regards this vehicle speed as the vehicle speed at the time when the rotational position of the TPMS sensor 2 is the highest point. The result is output to the map generation unit 12 together with the rotation position.

FIG. 5 is a diagram illustrating a method for calculating the rotational position of each wheel 1.
In FIG. 5, the time when the count value of the wheel speed pulse is input is t1, the time when the rotational position of the TPMS sensor 2 is the highest point is t2, and the time when the TPMS sensor 2 actually starts transmitting TPMS data. t3, the time when TPMSCU4 completes the reception of TPMS data is t4, and the time when the wheel speed pulse count value is input is t5. At this time, t1, t4, t5 can be actually measured, t3 can be calculated by subtracting the data length of TPMS data (specified value, for example, about 10 msec) from t4, and t2 is a time lag at the time of transmission from t3 ( It can be calculated in advance by experiments etc.).
Therefore, if the number of teeth at _t1 is z _t1 , the number of teeth at _t2 is z _t2 , and the number of teeth at _t5 is z _t5 ,
(t2-t1) / (t5-t1) = (z _t2 -z _t1 ) / (z _t5 -z _t1 )
Is established,
z _t2 -z _t1 = (z _t5 -z _t1 ) * (t2-t1) / (t5-t1)
Therefore, the number of teeth z _{t2 at} time t2 when the rotational position of the TPMS sensor 2 becomes the highest point is
z _t2 = z _t1 + (z _t5 -z _t1 ) * (t2-t1) / (t5-t1)
It becomes.

The left / right position determination unit 12 accumulates the rotation position of each wheel 1 calculated by the rotation position calculation unit 11 and the vehicle speed at that time for each sensor ID to obtain rotation position data. The rotation position data is updated each time the rotation position of the same sensor ID is calculated by the rotation position calculation unit 11.
The left-right position determination unit 12 determines the left-right position of the TPMS sensor 2 corresponding to the sensor ID by performing left-right position determination control as described below. Thereby, the wheel position of the TPMS sensor 2 corresponding to the sensor ID can be specified.
By performing this determination for all sensor IDs, the correspondence between each sensor ID and each wheel position is specified and registered by storing and updating in the memory 9.

[Left / Right Position Judgment Control Processing]
FIG. 6 is a flowchart showing the flow of the left / right position determination control process by the left / right position determination unit 12, and each step will be described below. In the following description, the case of sensor ID = 1 will be described, but the left / right position determination control processing is also performed in parallel for other IDs (ID = 2, 3, 4).
In step S1, it is determined whether data in the vicinity of a vehicle speed of 60 [km / h] to 100 [km / h] has been received. If YES, the process proceeds to step S2, and if NO, step S1 is repeated.
In step S2, the rotational positions are rearranged in order of increasing vehicle speed in each rotational position data.
In step S3, in each rotational position data, an approximate line having the horizontal axis as the rotational position (number of teeth) and the vertical axis as the vehicle speed is obtained.
In step S4, it is determined whether or not each rotational position is within ± 12 teeth from the approximate line. If YES, the process proceeds to step S5, and if NO, the process proceeds to step S8.
In step S5, it is determined whether or not the inclination of the approximate line is equal to or greater than zero. If YES, the process proceeds to step S6, and if NO, the process proceeds to step S7.
In step S6, the left / right position of the TPMS sensor 2 corresponding to sensor ID = 1 is determined as the right wheel, and this control is terminated.
In step S7, the left / right position of the TPMS sensor 2 corresponding to sensor ID = 1 is determined as the left wheel, and this control is terminated.
In step S8

Next, the operation will be described.
[Left / right position determination]
When the vehicle travels, the rotational speed of each wheel 1 varies depending on the difference between the inner and outer wheels when turning, the locking and slipping of the wheel 1, and the tire pressure difference. It is known that even during straight running, there is a difference in rotational speed between the front and rear wheels 1FL and 1FR and between the left and right wheels 1RL and 1RR due to a slight correction rudder by the driver and a difference in the left and right road surface conditions. In other words, the rotational speed of each wheel 1 varies depending on the traveling, whereas the TPMS sensor 2 and the wheel speed sensor 8 (the rotor teeth) rotate together, so that the transmission timing of certain TPMS data The rotational position calculated from the count value of the wheel speed pulse of the wheel speed sensor 8 of the same wheel is always synchronized regardless of the travel distance and the travel state.

At this time, the transmission timing of the TPMS data changes according to the vehicle speed.
FIG. 7 is a diagram showing a difference in TPMS data transmission timing of the TPMS sensor 2 of the right front wheel (or right rear wheel 1RR) due to a difference in vehicle speed, and FIG. 7 (a) shows an extremely low speed (for example, 5 [km / h 7) is a low-speed traveling (for example, 40 [km / h]), and FIG. 7 (c) is a high-speed traveling (for example, 90 [km / h]).
As shown in FIG. 7 (a), the main body 24 of the TPMS sensor 2 is assembled to the wheel rim 22 so as to be parallel to the ground when the TPMS sensor 2 reaches the uppermost point. Thus, the G sensor 2b outputs a value of + 1G when the TPMS sensor 2 is at the uppermost point, and TPMS data is output.
Here, the center of gravity of the main body 24 is set at a position closer to the button battery 2e than the surface 28 (see FIG. 3) including the tire rotation shaft and the valve hole 23. Therefore, the centrifugal force acting on the left side portion 24c is larger than the centrifugal force acting on the right side portion 24b, and the difference increases as the centrifugal acceleration acting on the main body portion 24 increases. At this time, since the air valve 20 that supports the main body portion 24 employs a snap-in method that is fixed to the valve hole 23 of the wheel rim 22 via the soft rubber portion 26, the rubber portion 26 is twisted and the main body portion 24 is twisted. Inclination occurs. When the main body 24 is tilted, as shown in FIG. 7B, the rotational position where the G sensor 2b outputs a value of + 1G, that is, the position where the main body 24 is parallel to the ground is the original position (the highest point). ), The rotation angle is advanced by the inclination angle θ of the main body 24.

Further, in the region where the vehicle speed is equal to or higher than the predetermined vehicle speed (60 [km / h]), as shown in FIG. 7 (c), in addition to the inclination of the main body 24 due to the twisting of the rubber part 26, The inclination angle θ of the main body 24 increases as the vehicle speed increases due to the inclination of the main body 24 due to the deformation of 24b itself. At this time, the amount of change in the inclination angle θ of the main body 24 with respect to the change in the vehicle speed is larger than that in the case where the vehicle speed is less than the predetermined vehicle speed.
In other words, for the right wheel, as the vehicle speed increases, the transmission timing of the TPMS data becomes later than the prescribed timing. When the rotational position data of the wheel speed sensor 8FR of the right front wheel 1FR is plotted by vehicle speed, as shown in FIG. Characteristics. Fig. 8 (a) plots the rotation position calculated from the wheel speed pulse of the wheel speed sensor 8FR of the right front wheel 1FR when the TPMS sensor 2FR attached to the right front wheel 1FR transmits TPMS data. The position has a characteristic of shifting to the larger number of teeth as the vehicle speed increases. Further, the vehicle has a characteristic that the inclination is small when the vehicle speed is less than 60 [km / h], and the inclination is large when the vehicle speed is 60 [km / h] or more. Note that the same characteristics can be obtained from the TPMS sensor 2RR and the wheel speed sensor 8RR of the right rear wheel 1RR.

  On the other hand, in the left wheel, the positions of the right side 24b and the left side 24c of the main body 24 with respect to the rotation direction of the wheel are reversed with respect to the right wheel, so the transmission timing of TPMS data is earlier than the prescribed timing as the vehicle speed increases. Thus, when the rotational position data of the wheel speed sensor 8FL of the left front wheel 1FL is plotted for each vehicle speed, the characteristics as shown in FIG. 8B are obtained. Fig. 8 (b) plots the rotational position calculated from the wheel speed pulse of the wheel speed sensor 8FL of the left front wheel 1FL when the TPMS sensor 2FL attached to the left front wheel 1FL transmits TPMS data. Has a characteristic of shifting to a smaller number of teeth as the vehicle speed increases. Further, the vehicle has a characteristic that the inclination is small when the vehicle speed is less than 60 [km / h] and the inclination is large when the vehicle speed is 60 [km / h] or more. Note that the same characteristics are obtained from the TPMS sensor 2RL and the wheel speed sensor 8RL of the left rear wheel 1RL.

Therefore, in the first embodiment, paying attention to the fact that the change characteristic with respect to the centrifugal acceleration of the rotational position synchronized with the transmission timing of the TPMS data having a certain sensor ID is different between the right wheel and the left wheel, the left / right position determination unit 12 Calculates the approximate line from the distribution of the rotational position with respect to the centrifugal acceleration (≈ vehicle speed) of each rotational position of each rotational position data, and the approximate line of the rotational position data with the smallest degree of variation of each rotational position with respect to the approximate line. Based on the shape (characteristic), the left and right positions of the transmitter 2d corresponding to the sensor ID are determined.
The rotational position data synchronized with the transmission timing of certain TPMS data can be determined from the degree of variation of each rotational position with respect to the approximate line. Then, by looking at the shape of the approximate line of the rotational position data, it is possible to determine which of the left and right wheels the change characteristic of the rotational position data with respect to the centrifugal acceleration is.
Therefore, in the tire pressure monitoring apparatus of the first embodiment, the left and right positions of the transmitters 2d can be determined by one G sensor 2b for each wheel 1, and the cost can be kept low.

The left / right position determination unit 12 excludes the rotational position data whose rotational position distance with respect to the approximate line is out of the predetermined range (± 12 teeth) from the candidates, and changes the shape of the approximate line of the remaining rotational position data to the last. Based on this, the left and right positions of the transmitter 2d corresponding to the sensor ID are determined.
When the distance between the approximate line and each rotational position is all within the predetermined range, the wheel corresponding to the rotational position data is likely to be the wheel of the transmitter 2d corresponding to the TPMS data. However, when the number of receptions of TPMS data is small or when the travel distance is small, a difference is hardly generated in the degree of variation of each rotational position with respect to the approximate line of each wheel. Note that it is easy to make a difference in the degree of variation after determining the degree of variation after the number of TPMS data reception reaches the predetermined number of revolutions or after the travel distance has reached the predetermined distance, but it takes time to determine the left and right positions. Cost.
On the other hand, in the first embodiment, a method is adopted in which rotational position data whose rotational position distance with respect to the approximate line exceeds a predetermined range, that is, rotational position data whose variation degree exceeds an allowable value, is sequentially removed from the candidates. The left and right positions of the transmitter 2d can be accurately determined while suppressing the determination time.

The left / right position determination unit 12 determines the right wheel when the inclination of the approximate line is greater than or equal to zero, and determines the left / right position of the transmitter 2d based on the inclination of the approximate line.
As the vehicle speed increases on the right wheel, the transmission timing of TPMS data becomes later than the prescribed timing. On the left wheel, the transmission timing of TPMS data becomes earlier than the prescribed timing as the vehicle speed increases. Therefore, the right and left positions of the transmitter 2d can be accurately determined by looking at the inclination of the approximation.
The left / right position determination unit 12 does not determine the left / right position of the transmitter 2d until TPMS data of 60 [km / h] or more is received.
As shown in FIG. 8, since the change characteristic according to the vehicle speed of the rotational position data synchronized with the transmission cycle of the TPMS data changes at the vehicle speed of 60 [km / h], it is 60 [km / h] or more. By including the rotational position data, it is possible to improve the determination accuracy of the left and right positions.

Next, the effect will be described.
The tire pressure monitoring device of the first embodiment has the following effects.
(1) A snap-in type air valve 20 fixed to the valve hole 23 of the wheel rim 22 of each wheel 1 via a rubber part 26, and a substrate 2g formed integrally with the air valve 20 in the tire 21. In addition, the pressure sensor 2a for detecting tire air pressure, the G sensor 2b for detecting centrifugal acceleration when the wheel 1 is rotating, and the tire when the value of the gravity acceleration dependent component of the centrifugal acceleration becomes + 1G A transmitter 2d that transmits air pressure information and a sensor ID by radio signal is attached, and a main body 24 having a center of gravity outside the plane including the tire rotation shaft and the valve hole 23, and a centrifugal direction acting on the main body 24 Centrifugal acceleration detecting means for detecting acceleration, receivers 3a and 3b provided on the vehicle body side for receiving radio signals, and wheels provided on the vehicle body side corresponding to each wheel 1 and proportional to the rotational speed of the wheel Wheel speed sensor 8 that outputs a speed pulse and each wheel speed sensor Rotation position calculation unit 11 that detects the rotation position of each wheel 1 from the count value of each wheel and the rotation position of each wheel 1 when a wireless signal including a certain sensor ID is transmitted is acquired with a plurality of different centrifugal accelerations. Each wheel 1 is accumulated as rotational position data, and an approximate line is calculated from the distribution of rotational positions with respect to centrifugal acceleration at each rotational position of each rotational position data. A left-right position determination unit 12 that determines the left-right position of the transmitter 2d corresponding to the sensor ID based on the shape of the approximate line of the position data.
Therefore, the rotational position data synchronized with the transmission timing of certain TPMS data can be determined from the degree of variation of each rotational position with respect to the approximate line, and the centrifugal direction of the rotational position data can be determined by looking at the shape of the approximate line of the rotational position data. It can be determined which of the left and right wheels the change characteristic with respect to acceleration is. As a result, the right and left positions of each transmitter 2d can be determined by one G sensor 2b for each wheel 1, and the cost can be kept low.

  (2) The left / right position determination unit 12 excludes the rotational position data whose rotational position distance from the approximate line is out of the predetermined range (± 12 teeth) from the candidates, and finally the approximate line of the remaining rotational position data Since the left and right position of the transmitter 2d corresponding to the sensor ID is determined based on the shape of the sensor ID, the left and right position of the transmitter 2d can be accurately determined while suppressing the determination time.

  (3) Since the left / right position determination unit 12 determines the left / right position of the transmitter 2d based on the inclination of the approximate line, the left / right position of the transmitter 2d can be accurately determined.

  (4) Since the left / right position determination unit 12 does not determine the left / right position of the transmitter 2d until TPMS data of 60 [km / h] or more is received, the left / right position determination accuracy can be improved.

(5) The centrifugal direction acceleration detecting means is the vehicle speed sensor 15, and the left / right position determination unit 12 determines the left / right position of the transmitter 2d based on the change characteristic of the rotation position data with respect to the vehicle speed of each rotation position data.
By not using the detection value of the G sensor 2, the amount of data transmitted by the TPMS sensor 2 can be reduced. Further, since the vehicle speed sensor 15 is mounted on all vehicles, the cost of adding a new sensor on the vehicle side can be saved.

[Other Examples]
The best mode for carrying out the present invention has been described with reference to the embodiments based on the drawings. However, the specific configuration of the present invention is not limited to the embodiments, and does not depart from the gist of the invention. Such design changes are included in the present invention.
For example, in the embodiment, an example in which two receivers are provided has been described, but one receiver may be disposed close to one of the vehicle front side and the vehicle rear side.
As the vehicle speed detecting means, a configuration for detecting the vehicle speed from the changing speed of the wheel speed pulse of the wheel speed sensor may be used. Since the ABS unit is mounted on most of the vehicles, and the wheel speed sensor is an essential component of the ABS unit, the cost of adding a new sensor on the vehicle side can be saved as in the embodiment.
In the embodiment, the vehicle speed sensor 15 is used as the centrifugal direction acceleration detecting means. However, the centrifugal direction acceleration detected by the G sensor 2b may be directly used.

Claims (5)

A snap-in type air valve fixed via an elastic body to the valve hole of the wheel rim of each wheel;
Tire pressure detecting means for detecting tire air pressure on a substrate formed integrally with the air valve inside the tire, acceleration detecting means for detecting centrifugal acceleration when the wheel is rotating, A transmitter that transmits the tire air pressure information and identification information unique to each transmitter by a radio signal when the value of the gravity acceleration dependent component of the centrifugal acceleration becomes a predetermined value is attached, and the tire rotation shaft and the valve hole A main body having a center of gravity outside the plane including
A centrifugal acceleration detecting means for detecting centrifugal acceleration acting on the main body;
A receiver provided on the vehicle body side for receiving the radio signal;
A wheel speed sensor provided on the vehicle body side corresponding to each wheel and outputting a wheel speed pulse proportional to the rotation speed of the wheel;
Rotation position detection means for detecting the rotation position of each wheel from the count value of each wheel speed pulse;
The rotational position of each wheel when a wireless signal including certain identification information is transmitted is acquired at a plurality of different centrifugal accelerations and stored as rotational position data of each wheel. The rotational direction of each rotational position of each rotational position data Approximate lines are calculated from the distribution of rotational positions with respect to acceleration, and the left and right positions of the transmitter corresponding to the identification information are determined based on the approximate line shape of the rotational position data with the smallest degree of variation of each rotational position with respect to the approximate line. Left and right position determination means for
A tire pressure monitoring device comprising: In the tire pressure monitoring device according to claim 1,
The left / right position determination means excludes rotational position data whose rotational position distance with respect to the approximate line is out of a predetermined range from the candidates, and identifies the identification information based on the shape of the approximate line of the remaining rotational position data. A tire air pressure monitor device that determines the left and right positions of a transmitter corresponding to the above. In the tire pressure monitoring device according to claim 1 or 2,
The tire pressure monitoring device according to claim 1, wherein the left / right position determining means determines a left / right position of the transmitter based on an inclination of the approximate line. The tire pressure monitoring device according to any one of claims 1 to 3,
The tire pressure monitoring device according to claim 1, wherein the left / right position determining means does not determine the left / right position of the transmitter until a rotational position at a centrifugal acceleration equal to or greater than a threshold value is detected. The tire pressure monitoring device according to any one of claims 1 to 4,
The centrifugal direction acceleration detection means is a vehicle speed detection means,
The tire pressure monitoring device according to claim 1, wherein the left / right position determination means determines the left / right position of the transmitter based on a change characteristic of rotation position data with respect to a vehicle speed of each rotation position data.

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