JP5741768B2 - Tire pressure monitoring device - Google Patents

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, addition and subtraction correction are performed by adding and subtracting a correction value corresponding to the centrifugal acceleration to the rotational position of each wheel when a radio signal including certain identification information is transmitted. The rotational position is calculated, and the left and right positions of the transmitter corresponding to the identification information are determined based on the addition and subtraction correction rotational positions of the wheels.

  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. It is an estimation map of the inclination angle θ according to the wheel speed dependent component of the centrifugal acceleration Gs. It is a figure which shows the calculation method of a dispersion | distribution characteristic value. 6 is a flowchart illustrating a flow of a left / right position determination control process by the TPMSCU 4 according to the first embodiment. It is a figure which shows the relationship between the rotation position (the number of teeth of a rotor) of each wheel 1FL, 1FR, 1RL, and 1RR when the rotation position of the TPMS sensor 2FL of the left front wheel 1FL becomes the highest point and the number of receptions of TPMS data . 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. It is a correction tooth number calculation map according to vehicle speed. It is a flowchart which shows the flow of the left-right position determination control processing by TPMSCU4 of Example 2.

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
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 Rotation position correction unit (Rotation position correction means)
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, and the wheel speed sensor 8 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 the centrifugal acceleration [G] acting on the TPMS sensor 2.
The temperature sensor 2f detects the temperature [° C.] in the tire.
The sensor CU2c is operated by electric power from the button battery 2e, and wirelessly transmits TPMS data including at least tire pressure information detected by the pressure sensor 2a, centrifugal acceleration acting on the TPMS sensor 2, and sensor ID (identification information). To transmit from the transmitter 2d. 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. 2 side changes the TPMS data transmission cycle, and TPMSCU4 side determines which TPMS sensor 2 is based on TPMS data radio wave intensity, TPMS data transmission cycle, each wheel speed pulse and centrifugal acceleration acting on TPMS sensor 2. Determine if it is a wheel.

[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 Judgment 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 rotation position. A correction unit (rotational position correction unit) 12 and a left / right position determination unit (left / right position determination unit) 13 are 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 simultaneously inputs the centrifugal acceleration detected by the G sensor 15 and outputs it to the rotational position correction unit 12 together with the calculated rotational 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 rotational position correction unit 12 inputs the rotational position (number of teeth z _t2 ) of each wheel 1 calculated by the rotational position calculation unit 11 and the centrifugal acceleration, and the wheel speed dependent component of the centrifugal acceleration (from the centrifugal acceleration to the gravity The inclination angle θ with respect to the initial position of the main body 24 is estimated from the value of the component excluding the acceleration dependent component) with reference to the map of FIG. FIG. 6 is an estimation map of the inclination angle θ according to the wheel speed dependent component of the centrifugal acceleration Gs. The inclination angle θ has a characteristic that increases as the wheel speed dependent component of the centrifugal acceleration Gs increases. . This characteristic can be obtained in advance by experiments or the like.
The rotation position correction unit 12 converts the estimated inclination angle θ into a correction tooth number (correction value) Δz, and adds correction by adding the correction tooth number Δz to the tooth number z _t2 calculated by the rotation position calculation unit 11 The rotation position (z _t2 + Δz) and the subtraction correction rotation position (z _t2 −Δz) obtained by subtracting the correction tooth number Δz are respectively calculated. Here, since the rotor has 48 teeth, the conversion from the inclination angle θ to the correction tooth number Δz can be realized by dividing the inclination angle θ by 7.5 [°].

The left-right position determination unit 13 accumulates the addition correction rotation position and the subtraction correction rotation position of each wheel 1 calculated by the rotation position correction unit 12 for each sensor ID to obtain rotation position data, and each rotation position for each sensor ID. The degree of data variation is calculated as a dispersion characteristic value.
FIG. 7 is a diagram illustrating a method of calculating the dispersion characteristic value. In the first embodiment, a unit circle (circle having a radius of 1) centered on the origin (0,0) is considered on each two-dimensional plane. 1 rotation position θ [deg] (= 360 × number of teeth of rotor / 48) is converted into coordinates (cosθ, sinθ) on the circumference of the unit circle. That is, the rotational position of each wheel 1 is regarded as a vector of length 1 with the origin (0,0) as the start point and the coordinates (cosθ, sinθ) as the end point, and the average vector (ave_cosθ, ave_sinθ) is calculated, and the scalar quantity of the average vector is calculated as the dispersion characteristic value X of the rotational position data.
(cosθ, sinθ) = (cos ((z _t2 +1) * 2π / 48), sin ((z _t2 +1) * 2π / 48))
Therefore, if the number of receptions of TPMS data of the same sensor ID is n (n is a positive integer), the average vector (ave_cosθ, ave_sinθ) is
(ave_cosθ, ave_sinθ) = ((Σ (cosθ)) / n, (Σ (sinθ)) / n)
The dispersion characteristic value X is
X = ave_cosθ ² + ave_sinθ ²
Can be expressed as

  Left and right position determination unit 13 received TPMS data corresponding to a certain sensor ID 10 times or more, and accumulated TPMS data at 60 [km / h] or more 5 times (predetermined number) When the dispersion characteristic value X of each rotational position data of the same sensor ID is compared, and the maximum value of the dispersion characteristic value X is equal to or greater than a predetermined left / right determination threshold value, the dispersion characteristic value X is the addition correction rotational position. In this case, it is determined that the transmitter 2d corresponding to the sensor ID is the left wheel, and if it is the subtraction correction rotation position, it is determined that the transmitter 2d is the right wheel. By executing 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. 8 is a flowchart showing the flow of the left / right position determination control process by the TPMSCU 4 according to the first embodiment. 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, the rotational position calculation unit 11 inputs TPMS data.
In step S2, the rotational position computing unit 11 computes the rotational position of each wheel 1.
In step S3, the rotational position correction unit 12 estimates the inclination angle θ with respect to the initial position of the main body 24 from the value of the wheel speed dependent component of the centrifugal acceleration with reference to the map of FIG.
In step S4, the rotation position correction unit 12 corrects the rotation position data of each wheel 1 with the correction tooth number Δz corresponding to the inclination angle θ, and calculates the addition correction rotation position and the subtraction correction rotation position.
In step S5, the left / right position determination unit 13 determines whether or not the TPMS data of sensor ID = 1 has been received 10 times or more. If YES, the process proceeds to step S6, and if NO, the process returns to step S1.

In step S6, the left / right position determination unit 13 determines whether or not TPMS data having a vehicle speed equal to or higher than a predetermined vehicle speed (for example, 60 [km / h]) is received five or more times among the TPMS data with the sensor ID = 1. If YES, the process proceeds to step S7. If NO, the process returns to step S1.
In step S7, the left / right position determination unit 13 calculates the dispersion characteristic value X of the rotational position data of each wheel 1.
In step S8, the left / right position determination unit 13 determines whether or not the maximum value of the dispersion characteristic value X is greater than or equal to a predetermined left / right determination threshold value. If YES, the process proceeds to step S9. If NO, the process proceeds to step S9. Return to S1.
In step S9, the left / right position determination unit 13 determines whether or not the highest dispersion characteristic value X is the subtraction correction rotation position. If YES, the process proceeds to step S10, and if NO, the process proceeds to step S11.
In step S10, the left / right position determination unit 13 determines that the left / right position of the TPMS sensor 2 corresponding to sensor ID = 1 is the right wheel, and this control is terminated.
In step S11, the left / right position determination unit 13 determines that the left / right position of the TPMS sensor 2 corresponding to sensor ID = 1 is the left wheel, and ends this control.

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 output cycle of the wheel speed sensor 8 for the same wheel is always synchronized (matched) regardless of the travel distance or travel state.

Fig. 9 shows the relationship between the rotational position of each wheel 1FL, 1FR, 1RL, 1RR (number of teeth on the rotor) and the number of TPMS data received when the rotational position of the TPMS sensor 2FL of the left front wheel 1FL is the highest point. (A) is the wheel speed sensor 8FL for the left front wheel 1FL, (b) is the wheel speed sensor 8FR for the right front wheel 1FR, (c) is the wheel speed sensor 8RL for the left rear wheel 1RL, and (d) is the right Corresponds to the wheel speed sensor 8RR of the rear wheel 1RR.
As is apparent from FIG. 9, the wheel positions (number of teeth) obtained from the wheel speed sensors 8FR, 8RL, 8RR of the other wheels (right front wheel 1FR, left rear wheel 1RL, right rear wheel 1RR) have a large degree of variation. On the other hand, the wheel position obtained from the wheel speed sensor 8FL of the own wheel (the left front wheel 1FL) has the smallest degree of variation, and the output cycle of the TPMS sensor 2FL and the output cycle of the wheel speed sensor 8FL are almost synchronized.

However, in a driving scene in which the vehicle speed changes from low speed to high speed, the rotational position obtained from the wheel speed sensor 8 of the own wheel converges within a predetermined range by shifting the transmission timing of the TPMS data from the specified timing. Disappear. That is, a difference in the degree of variation between the rotational position data of the own wheel and the rotational position data of the other wheel is unlikely to occur.
FIG. 10 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. 10 (a) is a diagram at an extremely low speed (for example, 5 [km / h )), FIG. 10 (b) is during low speed travel (for example, 40 [km / h]), and FIG. 10 (c) is during high speed travel (for example, 90 [km / h]).
As shown in FIG. 10 (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. 10B, 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. 10C, in addition to the inclination of the main body 24 due to the twist of the rubber part 26, the right side of the main body 24 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.
That is, 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.
On the other hand, FIG. 11 (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. The rotational position 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, the inclination angle θ of the main body 24 is estimated based on the wheel speed dependent component of the centrifugal acceleration when the TPMS data of a certain sensor ID is transmitted, and the inclination angle θ is set to the correction tooth number Δz. Then, the addition correction rotation position and the subtraction correction rotation position obtained by adding and subtracting the correction tooth number Δz are calculated and accumulated as rotation position data. The rotation position data has the smallest variation degree (the dispersion characteristic value X is large). ) Based on whether the rotational position data is the addition correction rotational position or the subtraction correction rotational position when the degree of variation of the rotational position data is equal to or less than a predetermined value (dispersion characteristic value X is equal to or greater than the left / right determination threshold value). Thus, the left and right positions of the transmitter 2d corresponding to the sensor ID are determined.
Since the inclination angle θ and the wheel speed dependent component of the centrifugal acceleration acting on the TPMS sensor 2 have a certain relationship, the inclination angle θ can be accurately estimated from the wheel speed dependent component of the centrifugal acceleration.
The correction tooth number Δz represents a deviation from a specified rotational position (uppermost point) corresponding to the centrifugal acceleration acting on the TPMS sensor 2 when the TPMS sensor 2 transmits TPMS data.

For this reason, one of the addition correction rotation position and the subtraction correction rotation position obtained by correcting the rotation position of the same wheel as the transmitter 2d corresponding to a certain sensor ID by the correction tooth number Δz has the rotation position of the TPMS sensor 2 at the highest point. Therefore, the rotational position obtained from the wheel speed sensor 8 of the own wheel converges within a predetermined range. As a result, a difference in the degree of variation between the rotational position data of the own wheel and the rotational position data of the other wheel is likely to occur, so that it is easy to determine the left and right positions of the transmitter 2d corresponding to the sensor ID.
At this time, as described above, from the relationship between the rotation direction of the wheel and the inclination direction of the main body 24, the transmission speed of the TPMS data for the right wheel becomes slower than the specified timing as the vehicle speed increases, and the left wheel is conversely faster. Therefore, when the addition correction rotation position has the smallest degree of variation, i.e., when each rotation position converges within a predetermined range by the correction that delays the timing, the right and left positions of the TPMS sensor 2 corresponding to the sensor ID are determined. It can be determined as the left wheel. On the other hand, when the subtraction correction rotation position has the smallest degree of variation, that is, when each rotation position has converged within a predetermined range by correction that advances the timing, the right and left positions of the TPMS sensor 2 corresponding to the sensor ID are Can be determined.
Therefore, since the right and left positions of each transmitter 2d can be determined by one G sensor 2b for each wheel 1, the cost can be kept low.

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 for detecting the rotation position of each wheel 1 from the count value of the wheel, and adding and subtracting the correction tooth number Δz corresponding to the detected centrifugal direction acceleration to the detected rotation position of each wheel 1 A rotational position correction unit 12 that calculates the added and subtracted corrected rotational position, and a left and right position determining unit 13 that determines the left and right position of the transmitter 2d corresponding to the sensor ID based on the added and subtracted corrected rotational position of each wheel; , With.
Thereby, since the left-right position of each transmitter 2d can be determined by one G sensor 2b for each wheel 1, the cost can be kept low.

(2) The left / right position determination unit 13 acquires the addition and subtraction correction rotation positions calculated from the rotation position of each wheel 1 when a wireless signal including a certain sensor ID is transmitted, and accumulates it as rotation position data. Then, the left and right positions of the transmitter 2d corresponding to the sensor ID are determined based on whether the rotational position data having the smallest variation degree of the rotational position data is the addition correction rotational position or the subtraction correction rotational position.
Thereby, the left-right position of each transmitter 2d can be determined with high accuracy.

(3) The left / right position determination unit 13 sets the addition correction rotation position and the subtraction correction rotation position of each wheel 1 on the two-dimensional plane from the origin (0,0) as a starting point and a point (cosθ, sinθ) is converted to a vector whose end point is calculated, the scalar quantity of the average vector (ave_cosθ, ave_sinθ) of each rotational position data vector is calculated as the dispersion characteristic value X, and each rotational position data is compared by comparing each dispersion characteristic value X. Obtain the degree of variation of.
As a result, it is possible to avoid the periodicity of the rotational position data and obtain the degree of variation of the rotational position.

  (4) The left / right position determination unit 13 corresponds to the sensor ID when the rotational speed data corresponding to a certain sensor ID is 5 or more when the vehicle speed is 60 [km / h] or higher. To determine the left and right positions of the transmitter 2d, the change amount of the correction tooth number Δz with respect to the vehicle speed change is larger than 60 [km / h], and the difference between the addition correction rotation position and the subtraction correction rotation position tends to occur By using a lot of rotational position data at / h or more, the determination accuracy of the left and right positions can be improved.

  (5) When the rotational position is at the highest point, the left wheel main body 24 has a center of gravity on the left side of the plane 28 including the tire rotation axis and the valve hole 23 when viewed from the inside of the vehicle. 13 is a transmitter 2d attached to the left wheel in order to determine the left and right positions of the transmitter 2d corresponding to the sensor ID as the left wheel when the rotation position data whose variation degree is equal to or less than a predetermined value is the addition correction rotation position. Can be determined.

  (6) When the rotation position is at the highest point, the right wheel main body 24 has a center of gravity on the left side of the plane 28 including the tire rotation shaft and the valve hole 23 when viewed from the inside of the vehicle, and the right / left position determination The unit 13 is attached to the right wheel in order to determine the right and left positions of the transmitter 2d corresponding to the sensor ID as the right wheel when the rotation position data whose variation degree is equal to or less than the predetermined value is the subtraction correction rotation position. The left and right positions of the transmitter 2d can be determined.

(7) The rotational position correction unit 12 increases the correction tooth number Δz as the detected centrifugal acceleration increases.
As the centrifugal acceleration increases, the transmission timing of TPMS data deviates from the specified timing. Therefore, the larger the centrifugal acceleration, the larger the correction tooth number Δz, so that one of the addition correction rotation position and the subtraction correction rotation position is set as the TPMS sensor. It is possible to approach the rotation position when the rotation position of 2 is at the uppermost point. Therefore, a difference is easily generated in the degree of variation between the rotational position data of the own wheel and the rotational position data of the other wheel, and determination of the left and right positions of the transmitter 2d is facilitated.

(8) The rotational position correction unit 12 estimates the inclination angle θ of the main body 24 from when the vehicle is stopped based on the detected centrifugal acceleration, and sets the correction tooth number Δz based on the estimated inclination angle θ. To do.
By determining the correction tooth number Δz from the inclination angle θ of the main body 24, one of the addition correction rotation position and the subtraction correction rotation position can be corrected to the rotation position when the rotation position of the TPMS sensor 2 is at the highest point. A difference is likely to occur between the rotational position data of the wheel and the rotational position data of the other wheel, and the determination of the left and right position of the transmitter 2d is facilitated.

[Example 2]
The second embodiment is different from the first embodiment in that the rotational position correction unit 12 calculates addition and subtraction corrected rotational positions by adding and subtracting the correction tooth number Δz according to the vehicle speed instead of the detected centrifugal acceleration. Is different.
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. Output to the rotational position correction unit 12 together with the rotational position.
The rotation position correction unit 12 calculates the correction tooth number (correction value) according to the vehicle speed from the map of FIG. 12 according to the rotation speed (number of teeth zt2) of each wheel 1 calculated by the rotation position calculation unit 11 and the corresponding vehicle speed. Δz is obtained, and an addition correction rotation position and a subtraction correction rotation position obtained by adding and subtracting the correction tooth number Δz corresponding to the vehicle speed to the rotation position of each wheel 1 are calculated.
FIG. 12 is a correction tooth number calculation map according to the vehicle speed, and as shown in FIG. 12, the correction tooth number Δz has a characteristic of increasing as the vehicle speed increases. Further, in the vehicle speed range where the vehicle speed is equal to or higher than the predetermined vehicle speed (60 [km / h]), the amount of change with respect to the vehicle speed change is larger than the vehicle speed range below the predetermined vehicle speed.
The rotational position correction unit 12 is a subtraction correction rotational position obtained by subtracting the correction tooth number Δz and the addition correction rotation position (zt2 + Δz) obtained by adding the correction tooth number Δz to the tooth number zt2 calculated by the rotation position calculation unit 11. (zt2-Δz) is calculated.

[Left / Right Position Judgment Control Processing]
FIG. 13 is a flowchart showing the flow of the left / right position determination control process by the TPMSCU 4, and each step will be described below. In addition, about the step which performs the same process as the left-right position determination control process of Example 1 shown in FIG. 8, the same step number is attached | subjected and description is abbreviate | omitted.
In step S21, the rotational position calculation unit 11 inputs the vehicle speed from the vehicle speed sensor 15.
In step S22, the rotation position correction unit 12 corrects the rotation position data of each wheel 1 from the map of FIG. 12 according to the vehicle speed, and calculates an addition correction rotation position and a subtraction correction rotation position.

Next, the operation will be described.
[Left / right position determination]
In the second embodiment, an addition correction rotation position and a subtraction correction rotation obtained by adding and subtracting the correction tooth number Δz corresponding to the vehicle speed to the rotation position of each wheel 1 detected when TPMS data of a certain sensor ID is transmitted. The position is calculated and accumulated as rotational position data. The rotational position data with the smallest degree of variation (large dispersion characteristic value X) among the rotational position data is less than a predetermined value (dispersion characteristic value X is determined to be left or right). When the rotation position data is the addition correction rotation position or the subtraction correction rotation position, the left and right positions of the transmitter 2d corresponding to the sensor ID are determined.
Here, as shown in FIG. 6, the correction tooth number Δz corresponding to the vehicle speed has a characteristic of increasing as the vehicle speed increases, and in the vehicle speed range where the vehicle speed is 60 [km / h] or higher, 60 [km / h]. The amount of change with respect to the vehicle speed change is larger than the vehicle speed range below h]. That is, the correction number of teeth Δz according to the vehicle speed represents a deviation from a specified rotational position (top point) according to the vehicle speed when the TPMS sensor 2 transmits TPMS data.

For this reason, one of the addition correction rotation position and the subtraction correction rotation position obtained by correcting the rotation position of the same wheel as the transmitter 2d corresponding to a certain sensor ID by the correction tooth number Δz has the rotation position of the TPMS sensor 2 at the highest point. Therefore, the rotational position obtained from the wheel speed sensor 8 of the own wheel converges within a predetermined range. As a result, a difference in the degree of variation between the rotational position data of the own wheel and the rotational position data of the other wheel is likely to occur, so that it is easy to determine the left and right positions of the transmitter 2d corresponding to the sensor ID.
At this time, as described above, from the relationship between the rotation direction of the wheel and the inclination direction of the main body 24, the transmission speed of the TPMS data for the right wheel becomes slower than the specified timing as the vehicle speed increases, and the left wheel is conversely faster. Therefore, when the addition correction rotation position has the smallest degree of variation, i.e., when each rotation position converges within a predetermined range by the correction that delays the timing, the right and left positions of the TPMS sensor 2 corresponding to the sensor ID are determined. It can be determined as the left wheel. On the other hand, when the subtraction correction rotation position has the smallest degree of variation, that is, when each rotation position has converged within a predetermined range by correction that advances the timing, the right and left positions of the TPMS sensor 2 corresponding to the sensor ID are Can be determined.
Therefore, since the right and left positions of each transmitter 2d can be determined by one G sensor 2b for each wheel 1, the cost can be kept low.

Next, the effect will be described.
In addition to the effects (1) to (6) of the first embodiment, the tire pressure monitoring device of the second embodiment has the effects listed below.
(9) A vehicle speed sensor 15 that detects the vehicle speed is provided, and the rotational position correction unit 12 adds and subtracts corrected rotations by adding and subtracting a correction value corresponding to the detected vehicle speed to the detected rotational position of each wheel. Calculate the position.
Thereby, since the left-right position of each transmitter 2d can be determined by one G sensor 2b for each wheel 1, the cost can be kept low.
(10) Since the correction tooth number Δz increases as the vehicle speed increases, the correction tooth number Δz corresponding to the vehicle speed is set to the specified rotational position (top point) according to the vehicle speed when the TPMS sensor 2 transmits TPMS data. The difference between the rotational position data of the same wheel as that of the transmitter 2d and the rotational position data of other wheels is likely to be different, so that the determination accuracy of the left and right positions can be improved.

[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.

Claims (12)

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 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;
Rotation position correction means for calculating an addition and subtraction correction rotation position obtained by adding and subtracting a correction value corresponding to the detected centrifugal acceleration to the detected rotation position of each wheel;
The addition and subtraction correction rotational position of each wheel, the rotational position data variation degree is equal to or less than a predetermined value, based on the relationship between the position of the center of gravity with respect to the surface, left and right transmitters corresponding to the identification information Left and right position determining means for determining a position;
A tire pressure monitoring device comprising: In the tire pressure monitoring device according to claim 1,
The left and right position determination means acquires the addition and subtraction correction rotation positions calculated from the rotation position of each wheel when a radio signal including certain identification information is transmitted, and accumulates the rotation position data as the rotation position data. Of the transmitter corresponding to the identification information on the basis of the position of the center of gravity point relative to the rotation position data and whether the rotation position data where the variation degree of each rotation position data is a predetermined value or less is the addition correction rotation position or the subtraction correction rotation position. A tire pressure monitoring device for determining a left-right position. In the tire pressure monitoring device according to claim 2,
The main body of the left wheel has a center of gravity on the left side of the plane including the tire rotation axis and the valve hole when viewed from the inside of the vehicle when the rotational position is at the uppermost point.
The left / right position determination means determines that the left / right position of the transmitter corresponding to the identification information is a left wheel when rotation position data whose variation degree is equal to or less than the predetermined value is the addition correction rotation position. Tire pressure monitoring device. In the tire pressure monitoring device according to claim 2 or claim 3,
The main body of the right wheel has a center of gravity on the left side of the plane including the tire rotation axis and the valve hole when viewed from the inside of the vehicle when the rotational position is at the uppermost point.
The left / right position determining means determines that the right / left position of the transmitter corresponding to the identification information is a right wheel when the rotational position data whose degree of variation is equal to or less than the predetermined value is the subtraction correction rotational position. Tire pressure monitoring device. The tire pressure monitoring device according to any one of claims 2 to 4,
The main body of the left wheel has a center of gravity on the right side of the plane including the tire rotation axis and the valve hole when viewed from the inside of the vehicle when the rotational position is at the uppermost point.
The left / right position determination means determines that the right / left position of the transmitter corresponding to the identification information is a right wheel when rotation position data whose variation degree is equal to or less than the predetermined value is the addition correction rotation position. Tire pressure monitoring device. In the tire pressure monitoring device according to any one of claims 2 to 5,
The main body of the right wheel has a center of gravity on the right side of the plane including the tire rotation axis and the valve hole when viewed from the inside of the vehicle when the rotational position is at the uppermost point.
The left / right position determining means determines that the left / right position of the transmitter corresponding to the identification information is a left wheel when the rotational position data whose degree of variation is equal to or less than the predetermined value is the subtraction correction rotational position. Tire pressure monitoring device. The tire pressure monitoring device according to any one of claims 2 to 6,
The left and right position determining means converts the addition and subtraction correction rotational positions of the wheels into a vector having a starting point on a two-dimensional plane and a point on the circumference of a unit circle as an end point. A tire air pressure monitoring device that calculates a scalar quantity of an average vector of vectors as a dispersion characteristic value and compares the dispersion characteristic values to obtain a degree of variation. The tire pressure monitoring device according to any one of claims 2 to 7,
The right and left position determining means, when the rotational position data when the vehicle speed is greater than or equal Jo Tokoro speed out of the rotational position data corresponding to a certain identification information is equal to or greater than a predetermined number of times, the right and left positions of the transmitters corresponding to the identification information The tire pressure monitoring device characterized by determining the tire pressure. The tire pressure monitoring device according to any one of claims 1 to 8,
The tire pressure monitoring device, wherein the rotational position correction means increases the correction value as the detected centrifugal acceleration increases. The tire pressure monitoring device according to any one of claims 1 to 9,
The rotational position correction means estimates a tilt angle of the main body from the time when the vehicle is stopped based on the detected centrifugal acceleration, and sets the correction value based on the estimated tilt angle. Tire pressure monitoring device. The tire pressure monitoring device according to any one of claims 1 to 10,
Vehicle speed detection means for detecting the vehicle speed,
The rotational position correction means calculates an addition and subtraction correction rotational position obtained by adding and subtracting a correction value corresponding to the detected vehicle speed to the detected rotational position of each wheel, and a tire air pressure monitoring device. . The tire pressure monitoring device according to claim 11,
The tire pressure monitoring device, wherein the correction value increases as the vehicle speed increases.

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