JP5736959B2 - Tire pressure monitoring device - Google Patents

Description

  The present invention relates to a tire air pressure monitoring device that monitors the air pressure of each tire of a vehicle.

  2. Description of the Related Art Conventionally, there is known a tire pressure monitoring device that determines which wheel position (attachment position of a tire to a vehicle) a tire pressure sensor transmitter attached to each wheel tire is located (for example, Patent Document 1). .

JP 2007-245982 A

When traveling, the transmitter rotates with the wheels and there may be a difference in the number of rotations between the wheels. Therefore, in order to accurately determine the wheel position of the transmitter, it is preferable to accurately detect the rotation position (rotation angle) at which the transmitter transmits in each wheel on the vehicle body side. However, at the rotational position of the transmitter, there is a point or a region (null point) where the intensity of radio waves received from the transmitter on the vehicle body side becomes low. Therefore, if the rotational position at which the transmitter transmits is located near the null point, the reception probability decreases, and the rotational position at the time of transmission of the transmitter cannot be accurately detected on the vehicle body side. There is a risk that the determination accuracy of the wheel position of the vehicle will decrease.
An object of the present invention is to provide a tire pressure monitoring device that can determine the wheel position of a transmitter with higher accuracy.

  In order to achieve the above object, in the present invention, a transmitter overlaps a signal to be transmitted into a plurality of frames, transmits each frame at intervals, and transmits each frame to the transmitter at the time of transmission of the frame. The rotational position information at the time of transmission of the transmitter is estimated on the vehicle body side including the rotational position information on the basis of the reception information of the received frames.

  Therefore, it is possible to improve the reception probability and more accurately detect the rotational position at the time of transmission of the transmitter in each wheel on the vehicle body side, so that the wheel position of the transmitter can be determined with higher accuracy. .

It is a block diagram of a tire pressure monitoring device. 2 is a configuration diagram of a TPMS sensor 2. FIG. In Example 1, it is a figure which shows the transmission method of each flame | frame of TPMS data. It is a control block diagram of TPMSCU4 for implementing wheel position determination control. It is a figure which shows the rotational position calculation method of TPMS sensor 2 (transmitter 2d). It is a figure which shows the rotational position calculation method of TPMS sensor 2 (transmitter 2d). It is a figure which shows the calculation method of a dispersion | distribution characteristic value. It is a flowchart which shows the flow of a wheel position determination control process. 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 . FIG. 4 is a diagram showing a null point in each wheel 1. In Example 2, it is a figure which shows the transmission method of each flame | frame of TPMS data. In Example 3, it is a figure which shows the transmission method of each flame | frame of TPMS data.

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 device of the first embodiment includes a TPMS (Tire Pressure Monitoring System) sensor 2, a receiver 3, a TPMS control unit (TPMSCU) 4, a display 5, a wheel speed sensor (rotational position detecting means) 8, Is provided. The TPMS sensor 2 is attached to each wheel 1, and the receiver 3, the TPMSCU 4, the display 5, and the wheel speed sensor 8 are provided on the vehicle body side.

The TPMS sensor 2 is attached to an air valve (not shown) position of the tire. FIG. 2 is a configuration diagram of the TPMS sensor 2. The TPMS sensor 2 includes a pressure sensor (tire pressure detecting means) 2a, an acceleration sensor (G sensor) 2b, a sensor control unit (sensor CU) 2c, a transmitter 2d, and a button battery 2e.
The pressure sensor 2a detects tire air pressure [kPa].
The G sensor 2b detects centrifugal acceleration [G] acting on the tire.
The sensor CU2c operates by the electric power from the button battery 2e, and transmits TPMS data including the tire air 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.

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.
One receiver 3 is provided in the vehicle, receives the radio signal output from each TPMS sensor 2, decodes it, and outputs it to the TPMSCU 4.

  TPMSCU4 reads each TPMS data, and from the sensor ID of the TPMS data, the correspondence between each sensor ID stored in the non-volatile memory 4d (see Fig. 3) and each wheel position (FL, FR, RL, RR) The wheel position corresponding to the TPMS data is determined with reference, and the tire air pressure included in the TPMS data is displayed on the display 5 as the corresponding wheel position air pressure. Further, when the tire air pressure falls below the lower limit value, the driver is notified of a decrease in air pressure by changing the display color, blinking display, warning sound, or the like.

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, A stator (permanent magnet and coil) arranged on the vehicle body side and 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 stator, so that the magnetic flux density changes and an electromotive force is generated in the coil. This voltage change is output to the ABSCU 6 as a wheel speed pulse signal.
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 time interval ΔT0 (for example, a cycle of 20 msec).

As described above, the TPMSCU 4 determines which wheel data the received TPMS data is based on the correspondence between each sensor ID stored in the memory 4d and each wheel position. Therefore, when tire rotation is performed while the vehicle is stopped, the correspondence between each sensor ID and each wheel position stored in the memory 4d does not match the actual correspondence, and the TPMS data is the data of which wheel. I don't know. Here, “tire rotation” refers to changing the mounting position of the tire among a plurality of wheels 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 4d, it is determined whether there is a possibility that tire rotation has been performed. If possible, change the TPMS data transmission cycle on each TPMS sensor 2 side, and on the TPMSCU4 side, which wheel each TPMS sensor 2 belongs to based on the TPMS data transmission cycle and each wheel speed pulse Determine.

[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 equal to or longer than a predetermined time T1 (for example, 15 minutes).
When the vehicle stop determination time immediately before the start of traveling is less than the predetermined time T1, the sensor CU2c performs the “normal mode” in which TPMS data is transmitted at regular intervals (eg, 1 minute intervals). On the other hand, when the vehicle stop determination time is equal to or longer than the predetermined time T1, the sensor CU2c transmits TPMS data at a constant rotational position that is shorter than the transmission interval in the normal mode (for example, approximately 16 seconds). Implement "Position transmission mode".

  The sensor CU2c executes the fixed position transmission mode until the number of transmissions of TPMS data reaches a predetermined number N1 (for example, 40 times). The sensor CU2c shifts to the normal mode when the number of transmissions reaches the predetermined number N1. If it is determined that the vehicle has stopped before the number of transmissions of TPMS data reaches the predetermined number N1, if the vehicle stop determination time is less than the predetermined time T1 (15 minutes), the number of transmissions before the vehicle stops until the predetermined number N1 is reached. The fixed position transmission mode is continued, and when the vehicle stop determination time is equal to or longer than the predetermined time T1, 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, TPMS data is output at the highest point by outputting TPMS data at the peak of gravity acceleration dependent component (+1 [G]).

  In the fixed position transmission mode, as shown in FIG. 3, the sensor CU2c transmits a plurality of frames, specifically, three frames having the same content including tire pressure information and sensor ID for each transmission of TPMS data. To do. The first frame is transmitted at the top point, and other frames are transmitted at intervals. Specifically, the second frame is transmitted after a first time interval ΔT1 (for example, 100 msec) from the transmission of the first frame, and the third frame is transmitted from the transmission of the second frame to a second time interval ΔT2 (for example, 140 msec). ) Send later. Each frame is given a frame number (1 to 3) as identification information so that it can be seen what number the frame is.

[Auto learning mode]
The TPMSCU 4 determines that there is a possibility that the tire rotation has been performed when the elapsed time from the OFF to the ON of the ignition switch is equal to or longer than a predetermined time T2 (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 T2. "Mode" is implemented. On the other hand, when the elapsed time from the ignition switch to the ON is equal to or longer than the predetermined time T2, the “auto learning mode” for determining the wheel position of each TPMS sensor 2 is performed. The auto-learning mode is performed until the wheel positions of all the TPMS sensors 2 are determined, or until a predetermined cumulative traveling time (for example, 8 minutes) has elapsed from the start of the mode. When the wheel positions of all the TPMS sensors 2 are determined, or when a predetermined accumulated traveling time has elapsed, the monitor mode is entered.

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, air pressure is displayed and air pressure drop warning is performed based on the correspondence between each sensor ID and each wheel position currently stored in the memory 4d.
The TPMSCU 4 receives the wheel speed pulse count value from the ABS control unit (ABSCU) 6 via the CAN communication line 7 during the auto-learning mode, and performs wheel position determination control as described below.

[Wheel position determination control]
FIG. 4 is a control block diagram of the TPMSCU 4 for performing the wheel position determination control. The TPMSCU 4 includes a rotational position calculation unit 4a, a dispersion calculation unit 4b, a wheel position determination unit 4c, and a memory 4d.
The rotational position calculation unit 4a inputs the decoded TPMS data output from the receiver 3 and the count value of each wheel speed pulse output from the ABSCU 6 to the CAN communication line 7, and outputs each TPMS sensor 2 (transmitter 2d). ) (When the rotational position becomes the highest point), the rotational position (number of teeth of the rotor z) of each wheel 1 is calculated. Here, the “number of teeth of the rotor” indicates which tooth of the rotor is counted by the wheel speed sensor 8, and the count value of the wheel speed pulse is set to the count value for one rotation of the tire (for one rotation). The number of teeth can be obtained by the remainder divided by z = 48). In Example 1, the remainder obtained by dividing the count value of the wheel speed pulse input first after the start of the auto-learning mode by the number of teeth for one rotation (= 48) is used as the reference number of teeth. The number of teeth is determined based on the count number of wheel speed pulses from (current count value−reference number of teeth).

FIG. 5 is a diagram illustrating a calculation method of the rotational position of the TPMS sensor 2 (transmitter 2d) in each wheel 1, which is executed by the rotational position calculation unit 4a.
Each time the rotational position calculation unit 4a receives TPMS data (first to third frames), it stores the reception time and data contents. Each time the count value of the wheel speed pulse is received via the CAN communication line 7, the input time and count value are stored.

First, a calculation method when the first frame is received will be described. In FIG. 5, the time when the wheel speed pulse count value (previous value) was input immediately before the start of reception of TPMS data (first frame) is t1, and the rotational position of the TPMS sensor 2 is the highest point. The time when the transmission of (first frame) is commanded is t2, and the time when TPMS sensor 2 actually starts transmitting TPMS data (first frame) (the time when TPMSCU4 starts receiving the first frame) can be regarded as the same. .) Is t3, the time when TPMSCU4 has finished receiving TPMS data (first frame) (it can be considered the same as the time when TPMS sensor 2 finished sending the first frame), t4, TPMS data (first frame) T5 is the time at which the count value (current value) of the wheel speed pulse is input immediately after the reception of is completed. The rotational position calculation unit 4a stores the times t1, t4, and t5, and the transmission time Δt1 of the TPMS data (first frame) from the time t4 (specified in advance as a value unique to the transmitter 2d according to the data length) For example, the time t3 is calculated by subtracting about 10 msec) (t4−Δt1 = t3). Also, the time t2 is calculated by subtracting the transmission time lag Δt0 (which can be obtained in advance through experiments or the like) from the time t3 (t3−Δt0 = t2). Instead of calculating the time t2 from the time t4, the time t3 may be directly detected and stored, and the time t2 may be calculated from the time t3.
Therefore, if the number of teeth of the rotor at time t1 is z _t1 , the number of teeth at time 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 transmission is commanded with the rotational position of the TPMS sensor 2 as the highest point is
z _t2 = z _t1 + (z _t5 -z _t1 ) × (t2-t1) / (t5-t1) (1)
Can be calculated. {(Z _t5 -z _t1 ) / (t5 -t1)} in the above formula (1) corresponds to the number of teeth per unit time.
In some cases, the count value of the wheel speed pulse is input during reception of TPMS data (see FIG. 6). Also in this case, based on the time t1 when the count value of the wheel speed pulse was input immediately before receiving the TPMS data and the time t5 when the count value of the wheel speed pulse was input immediately after receiving the TPMS data, the above formula ( The number of teeth z _t2 at time t2 can be calculated using 1).
As described above, for each wheel 1, the rotational position calculation unit 4a receives the reception information (reception completion time t4) of the radio signal (transmission data) from the transmitter 2d and the wheels input via the CAN communication line 7. Based on the rotational position information (input time t1, t5, number of teeth z _t1 , z _t5 ) of 1, the rotational position (number of teeth z _t2 ) at the time of transmission of the transmitter 2d (transmission command time _t2 ) is estimated.

Next, a calculation method when the second frame is received without receiving the first frame will be described. The second frame is transmitted 100 msec after the transmission of the first frame, that is, after the time interval ΔT1 for five times of the period ΔT0 (20 msec) in which the count value of the wheel speed pulse is input. Therefore, if z _t1 and z _t5 before 5 periods (ΔT0 × 5) are used in the above equation (1), when the rotational position of the TPMS sensor 2 reaches the highest point (the time when the transmission of the first frame is commanded) The rotational position z _t2 of the wheel 1 at t2) can be calculated. Specifically, the time when the wheel speed pulse count value (previous value) was input immediately before the start of reception of the second frame is t1 ′, and the second frame after 100 msec from the transmission command time t2 of the first frame. T2 ', the time when TPMS sensor 2 actually started the transmission of the second frame, t3', the time when TPMSCU4 completed the reception of the second frame, t4 ', the reception of the second frame T5 ′ is the time when the count value (current value) of the wheel speed pulse is input immediately after the completion of. The rotational position calculation unit 4a stores the times t1 ′, t4 ′, t5 ′, and determines that the second frame is received from the frame number,
t1 = t1 '-100msec
t4 = t4 '-100msec
t5 = t5 '-100msec
Thus, times t1, t4, and t5 (see FIG. 5) when the first frame is received are calculated. Further, the rotational position calculation unit 4a stores the number of teeth z _t1 at the time t1 and the number of teeth z _t5 at the time _t5 . further,
(t2-t1)
= {t4-(t4-t3)-(t3-t2)-t1}
= (t4 '-(t4'-t3 ')-(t3'-t2 ')-t1'}
Is established. That is, (t4 '-t1') = (t4-t1), (t4 '-t3') = (t4-t3) = Δt1, and (t3 '-t2') = (t3-t2) = Δt0. Therefore, the number of teeth z _{t2 at} time t2 when the rotational position of the TPMS sensor 2 becomes the highest point can be calculated by the above equation (1). After calculating the number of teeth at the transmission command time t2 ′ of the second frame by the same method as the above equation (1), the number of teeth at the transmission command time t2 of the first frame is subtracted by subtracting the number of teeth for 100 msec. The number z _t2 may be calculated.

Next, a calculation method when the third frame is received without receiving the first and second frames will be described. The third frame is transmitted 140 msec after the transmission of the second frame, that is, after a time interval ΔT2 of seven times (ΔT0 × 7) of the period ΔT0 (20 msec) in which the count value of the wheel speed pulse is input. Therefore, when the rotational position calculation unit 4a determines that the third frame is received from the frame number, z _t1 and z _t5 before 12 (= 5 + 7) periods (ΔT0 × 12) in the above equation (1) are used. Similarly to the above-described case where the second frame is received, the number of teeth z _t2 when the rotational position of the TPMS sensor 2 becomes the highest point is calculated.

The time interval ΔT between frames is not limited to a multiple of the input period ΔT0 (20 msec) of the count value of the wheel speed pulse, and any value can be used. Also in this case, the number of teeth z _t2 when the rotational position of the TPMS sensor 2 is at the highest point (time t2 when the transmission of the first frame is commanded) is obtained from the information received from the transmitter 2d (other than the first frame). It can be calculated based on frame reception start time or reception completion time) and rotational position information (count value input time and number of teeth) input via the CAN communication line 7. In the first embodiment, the time intervals ΔT1 and ΔT1 between frames are set to a multiple (100 msec, 140 msec) of the input cycle ΔT0 (20 msec) from the CAN communication line 7, so that the calculation can be simplified.

The dispersion calculation unit 4b accumulates the rotation position (the number of teeth z _t2 ) of each wheel 1 calculated by the rotation position calculation unit 4a for each sensor ID, and sets the rotation position data for each sensor ID. The degree of variation is calculated as a dispersion characteristic value. The calculation of the dispersion characteristic value is performed every time the rotation position of the same sensor ID is calculated by the rotation position calculation unit 4a.
FIG. 7 is a diagram illustrating a method for calculating the dispersion characteristic value. In Example 1, a unit circle (circle having a radius of 1) centered on the origin (0,0) on a two-dimensional plane is considered, and the rotational position θ [deg] of each wheel 1 (= 2π × the number of teeth of the rotor) z _t2 / 48) is converted into the 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). Then, the scalar quantity of the average vector is calculated as the dispersion characteristic value X of the rotational position data.
(cosθ, sinθ) = (cos (2π × z _t2 ) / 48), sin (2π × z _t2 ) / 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)
It becomes. Dispersion characteristic value X is
X = ave_cosθ ² + ave_sinθ ²
Can be expressed as
The rotational position of the wheel 1 is angular data with periodicity. By calculating the scalar quantity of the average vector as the dispersion characteristic value X, it is possible to obtain the degree of variation in rotational position while avoiding periodicity.

The wheel position determination unit 4c compares the dispersion characteristic values X of the rotational position data of the same sensor ID calculated by the dispersion calculation unit 4b. When the maximum dispersion characteristic value X is greater than the first threshold (for example, 0.57), and all the remaining three dispersion characteristic values X are less than the second threshold (for example, 0.37) , The wheel position of the rotational position data corresponding to the highest dispersion characteristic value X, that is, the wheel position of the wheel speed sensor 8 that detected the rotational position data is the value of the TPMS sensor 2 corresponding to the sensor ID of the rotational position data. Determine wheel position. By performing this determination for all the sensor IDs, the correspondence between each sensor ID and each wheel position is obtained and registered by updating the memory 4d.
Rather than simply selecting the maximum value of the dispersion characteristic value X, a certain determination accuracy can be ensured by comparing the maximum value with the first threshold value (0.57). Furthermore, by comparing the dispersion characteristic value X other than the maximum value with the second threshold value (0.37), it can be confirmed that there is a difference of more than the predetermined value (0.2) between the maximum value and the other three values. Can be further enhanced. For this reason, it is possible to achieve both of ensuring the determination accuracy and shortening the determination time with a small number of receptions of 10 times.

[Wheel position determination control processing]
FIG. 8 is a flowchart illustrating the flow of the wheel position determination control process 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 wheel position determination control processing is similarly performed in parallel for other IDs (ID = 2, 3, 4).
In step S1, the rotational position calculation unit 4a receives TPMS data of sensor ID = 1. If at least one of the first to third frames is received, TPMS data is received once.
In step S2, the rotational position calculation unit 4a calculates the rotational position of each wheel 1 based on the information of the received data (any one of the first to third frames).

In step S3, the dispersion calculation unit 4b calculates the dispersion characteristic value X of the rotational position data of each wheel 1.
In step S4, it is determined whether or not the TPMS data of sensor ID = 1 has been received a predetermined number of times (for example, 10 times) or more. If YES, the process proceeds to step S5. If NO, the process returns to step S1.
In step S5, the wheel position determination unit 4c determines whether or not the maximum value of the dispersion characteristic value is greater than the first threshold value 0.57 and the remaining dispersion characteristic value is less than the second threshold value 0.37. Determine. If YES, the process proceeds to step S6. If NO, the process proceeds to step S7.

In step S6, the wheel position determination unit 4c determines that the wheel position of the rotational position data corresponding to the highest dispersion characteristic value is the wheel position of the sensor ID, and ends the auto-learning mode.
In step S7, the wheel position determination unit 4c determines whether or not a predetermined cumulative travel time (for example, 8 minutes) has elapsed since the start of the auto-learning mode. If NO, the process returns to step S1, and if YES, the auto-learning mode is terminated.
If the wheel positions can be determined for all the sensor IDs within a predetermined cumulative travel time, the wheel position determination unit 4c registers the correspondence between each sensor ID and each wheel position by storing and updating the memory 4d. On the other hand, if the wheel positions cannot be determined for all the sensor IDs within the predetermined cumulative travel time, the correspondence relationship between each sensor ID and each wheel position currently stored in the memory 4d is continuously used.

Next, the operation will be described.
Each 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 travel is 15 minutes or more, and shifts from the normal mode to the fixed position transmission mode. In the fixed position transmission mode, each TPMS sensor 2 transmits TPMS data when 16 seconds have elapsed from the previous transmission time and its own rotational position has reached a predetermined position (the highest point). On the other hand, TPMSCU4 shifts from the monitor mode to the auto-learning mode when the elapsed time from the ignition switch OFF to ON is 15 minutes or more. In auto-learning mode, every time TPMSCU4 receives TPMS data from each TPMS sensor 2, the rotational position of the TPMS sensor 2 is set to the predetermined position from the input time of the count value of the wheel speed pulse, the reception completion time of the TPMS data, etc. Calculate the rotational position (number of teeth of the rotor) of each wheel 1 when it reaches (top point). The TPMSCU 4 repeats this calculation 10 times or more and accumulates it as rotational position data, and determines the wheel position corresponding to the rotational position data having the smallest variation among the rotational position data as the wheel position of the TPMS sensor 2.

Here, by setting the transmission interval of TPMS data to 16 seconds + α, a certain amount of accumulated travel distance can be secured until TPMS data is received 10 times or more. Therefore, a sufficient difference can be obtained in the dispersion characteristic value X between the own wheel and the other wheel, and the wheel position can be accurately determined.
The TPMS sensor 2 shifts to the normal mode when transmitting TPMS data 40 times in the fixed position transmission mode. That is, the TPMS sensor 2 consumes the most power of the button battery 2e when transmitting TPMS data. Therefore, if the position of each wheel cannot be determined even after a sufficient accumulated travel time has elapsed, the battery life of the button battery 2e can be prevented from decreasing by terminating the fixed position transmission mode and shifting to the normal mode.
On the other hand, if TPMSCU4 cannot determine the correspondence between each sensor ID and each wheel position even after 8 minutes have elapsed since the start of auto-learning mode, it ends auto-learning mode and shifts to monitor mode. To do. The total number of TPMS data transmitted from the TPMS sensor 2 when the cumulative traveling time has passed 8 minutes is less than 30, and the auto-learning mode can be terminated almost in synchronization with the end of the fixed-position transmission mode of the TPMS sensor 2.

Among conventional tire pressure monitoring devices, the same number of receivers as TPMS sensors are placed in close proximity to each receiver, and the wheel position of each TPMS sensor is determined based on the radio wave intensity (difference) of the received radio signal It has been known. However, this apparatus requires a receiver layout that takes into account sensor output, receiver sensitivity variations, and the harness antenna effect, and the performance depends on the reception environment and layout. Further, since four receivers are necessary, the cost becomes high.
On the other hand, in the tire pressure monitoring device of the first embodiment, the wheel position of each TPMS sensor 2 can be determined without using the radio wave intensity (difference). Therefore, the wheel position of each TPMS sensor 2 can be determined regardless of the reception environment and layout. Further, since only one receiver 3 is required, the cost can be kept low.

  Further, among conventional tire pressure monitoring devices, there is known a device in which each TPMS sensor is provided with a tilt sensor and the wheel position of each TPMS sensor is determined using the relationship between the wheel position of each TPMS sensor and the tilt angle. (For example, patent document 1). However, in this device, the correspondence between the wheel position and the inclination angle of each TPMS sensor changes due to the difference in the rotational speed of the four wheels depending on the running. Therefore, the wheel position of each TPMS sensor cannot be accurately determined. That is, when the vehicle travels, the rotational speed of each wheel 1 varies depending on the difference between the inner and outer wheels during turning, the lock and slip 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. That is, the rotational speed of each wheel 1 varies depending on the traveling.

On the other hand, in the first embodiment, since the TPMS sensor 2 and the wheel speed sensor 8 (the rotor teeth thereof) rotate together, the output cycle of the wheel speed sensor 8 of the same wheel with respect to the output cycle of a certain TPMS sensor 2 Paying attention to the fact that it always synchronizes regardless of the travel distance and driving state, the rotational position of the TPMS sensor 2 detected on the wheel 1 side (output of the TPMS sensor 2) and the rotational position of the TPMS sensor 2 detected on the vehicle body side The wheel position of the TPMS sensor 2 is determined based on the correspondence with (the output of the wheel speed sensor 8). Specifically, the TPMS sensor 2 on the wheel 1 side detects the rotational position of the wheel 1 based on the gravity acceleration-dependent component of the centrifugal acceleration detected by the G sensor 2b, and the rotational position is a predetermined reference position ( In the first embodiment, TPMS data is transmitted when the top point is reached. Each time the TPMSCU 4 on the vehicle body receives TPMS data from each TPMS sensor 2, the rotational position (rotor) of each wheel 1 when the TPMS data is transmitted (that is, when the TPMS sensor 2 is at the reference position = the highest point). The number of teeth z _t2 ) is calculated.
While traveling, the rotational position (number of teeth z _t2 ) of each wheel 1 calculated in response to transmission from a certain TPMS sensor 2 (for example, ID = 1) is within a certain range only at certain wheel 1 (for example, the left front wheel 1FL). It is assumed that it is limited to. In this case, in this wheel 1 (left front wheel 1FL), the rotational position of the TPMS sensor 2 detected on the vehicle body side (the calculated value z _t2 ) and the rotational position of the TPMS sensor 2 detected on the wheel 1 side (ID = This means that there is a one-to-one correspondence with the reference position where the TPMS sensor 2 of 1 transmits (the highest point). Therefore, in the above case, it can be determined that the wheel position of the TPMS sensor 2 (ID = 1) is the wheel 1 (the left front wheel 1FL).

  Thus, the wheel position of each TPMS sensor 2 can be accurately determined by looking at the degree of variation in the rotational position data of each wheel 1 with respect to the transmission cycle of TPMS data. 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. FIG. (a) Wheel speed sensor 8FL for left front wheel 1FL, (b) Wheel speed sensor 8FR for right front wheel 1FR, (c) Wheel speed sensor 8RL for left rear wheel 1RL, (d) Wheel for right rear wheel 1RR Corresponds to speed sensor 8RR. 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 (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. .

The wheel position of the TPMS sensor 2 may be determined by comparing the rotational position detected on the wheel 1 side (output of the TPMS sensor 2) with the rotational position detected on the vehicle body side (output of the wheel speed sensor 8). Therefore, it is not always necessary to use the dispersion characteristic value X as in the first embodiment. For example, if there is a wheel 1 with the smallest change in the calculated value z _t2 by the wheel speed sensor 8 of each wheel 1 with respect to the output of a certain TPMS sensor 2 after traveling a predetermined distance, the position of this wheel 1 is determined as the TPMS sensor 2 The wheel position can be determined. In the first embodiment, the wheel position of each TPMS sensor 2 can be determined with higher accuracy by looking at the degree of variation using the dispersion characteristic value X.

The G sensor 2b of the TPMS sensor 2 may be a G sensor that detects acceleration in the rotational direction (perpendicular to the centrifugal direction), for example, instead of the acceleration in the centrifugal direction of the wheel 1. Further, the reference position at which the TPMS sensor 2 transmits (outputs) is not the highest point, but may be another rotational position, for example, the frontmost point, the last point, or the lowest point of the wheel 1. In the first embodiment, the fact that the rotational position of the TPMS sensor 2 is at the highest point is calculated from the gravity acceleration dependent component of the centrifugal acceleration detected by the G sensor 2b. The G sensor 2b is commonly used for stopping and running in existing tire pressure monitoring devices, so the existing TPMS sensor can be diverted, and the cost of adding a new sensor to the TPMS sensor 2 side can be saved. Can do. Further, by setting the highest point as the reference position, it can be easily determined by the G sensor 2b that the rotational position of the TPMS sensor 2 is at the reference position.
Furthermore, in Example 1, the TPMSCU 4 calculates the rotational position of each wheel 1 from the output of the wheel speed sensor 8 (the count value of the wheel speed pulse). Since the ABS unit is mounted on most of the vehicles, and the wheel speed sensor 8 is an essential configuration for the ABS unit, the cost of adding a new sensor on the vehicle side can be saved.

  However, when an existing system is used, the wheel speed pulse output from the wheel speed sensor 8 is input to the TPMSCU 4 from the ABSCU 6 via the CAN communication line 7 as a discrete count value with a predetermined period ΔT0. Therefore, the transmission timing from the TPMS sensor 2 to the TPMSCU 4 and the input timing of the count value of the wheel speed pulse to the TPMSCU 4 do not match. As shown in FIG. 5, the time t1, t5 when the count value of the wheel speed pulse is input, and the time t2 when the rotation position of the TPMS sensor 2 is set to the reference position (top point) and the transmission of TPMS data is commanded. There is a gap (time lag). Therefore, when the rotational position of the TPMS sensor 2 becomes the reference position (the highest point) (that is, when the TPMS sensor 2 transmits), the rotational position of each wheel 1 (the number of teeth of the rotor) It cannot be calculated accurately based on the count value of the wheel speed pulse. In other words, when the rotational position of the TPMS sensor 2 detected on the wheel 1 side (uppermost point) is associated with the rotational position of the wheel 1 detected on the vehicle body side (rotor tooth number), it is input from the CAN communication line 7 If the count value is used as it is as the rotational position of the wheel 1, the association becomes inaccurate. Therefore, the determination accuracy of the wheel position of the TPMS sensor 2 may be reduced. If the input cycle ΔT0 of the count value from the ABSCU 6 to the TPMSCU 4 is shortened, the input timing of the count value to the TPMSCU 4 may be brought closer to the transmission timing from the TPMS sensor 2 to the TPMSCU 4, and the determination accuracy may be improved. However, in order to shorten the period ΔT0, it is necessary to dramatically increase the communication speed via the CAN communication line 7, which increases the cost of the microcomputer (CU) and the like.

On the other hand, in the first embodiment, the TPMSCU4 (rotational position calculation unit 4a) receives the information received from the TPMS sensor 2 (reception completion time t4) and wheels that are discretely input to the TPMSCU4 at a predetermined period ΔT0 (20 msec). Based on the rotational position information (input time t1, t5, number of teeth z _t1 , z _t5 ) of 1, the rotational position (number of teeth z _t2 ) of the TPMS sensor 2 is estimated. Specifically, the number of teeth z _t2 at time t2 when the rotational position of the TPMS sensor 2 becomes the reference position (the highest point) is calculated by the above equation (1).
Therefore, even when the rotational position of the wheel 1 (the count value of the wheel speed pulse) is discretely detected on the vehicle body side, the rotational position of each TPMS sensor 2 (when the TPMS sensor 2 becomes the reference position (the highest point)) The rotational position of each wheel 1 (the number of teeth z _t2 )) can be accurately estimated. For this reason, the rotational position of the wheel 1 (number of teeth of the rotor) at the time of transmission of the TPMS sensor 2 estimated on the vehicle body side, and the rotational position of the wheel 1 at the time of transmission of the TPMS sensor 2 detected on the wheel side (top point) Can be associated with high accuracy. Therefore, it is possible to accurately estimate the wheel position of the TPMS sensor 2 while suppressing an increase in cost using an existing system.

It is also possible to calculate the rotational position of wheel 1 (the number of teeth z of the rotor) at the actual transmission start time (time t3), not at the time of transmission command of TPMS data (time t2). That is, assuming that the transmission delay (time lag Δt0) of the TPMS sensor 2 is zero, the rotational position z _t3 at time _t3 is calculated by the following equation (2), and this is used to determine the degree of variation of each rotational position data for each sensor ID. It may be used for this purpose.
z _t3 = z _t1 + (z _t5 -z _t1 ) × (t3-t1) / (t5-t1) (2)
In the first embodiment, the error due to the time lag Δt0 (= t3-t2) from the transmission command of the TPMS sensor 2 to the actual transmission is taken into account, and the rotational position z _t2 is calculated by the equation (1) to correct the transmission delay Δt0. To do. Therefore, the rotational position (number of teeth) of each wheel 1 when the rotational position of each TPMS sensor 2 actually becomes the reference position (uppermost point) can be calculated with higher accuracy. The information of the time lag Δt0 may be input to the TPMSCU 4 (rotational position calculation unit 4a) together with the data transmitted from the TPMS sensor 2, or may be stored in the TPMSCU 4 in advance.

Alternatively, the rotational position (number of teeth of the rotor z) of the wheel 1 at the time of completion of reception (time t4), not at the time of starting transmission of TPMS data (time t2 to t3) may be calculated. That is, assuming that the transmission time Δt1 = (t4-t3) of TPMS data is zero, the rotational position z _t4 at time _t4 is calculated by the following equation (3), and this is the degree of variation of each rotational position data for each sensor ID It may be used as a reference position for determining.
z _t4 = z _t1 + (z _t5 -z _t1 ) × (t4-t1) / (t5-t1) (3)
In the first embodiment, the rotational position z _t2 is calculated by Equation (1) in consideration of the transmission time Δt1 of TPMS data. Therefore, the rotational position (number of teeth) of each wheel 1 when the rotational position of each TPMS sensor 2 becomes the reference position (the highest point) can be calculated more accurately in accordance with the actual situation.

  In the first embodiment, the TPMS sensor 2 (transmitter 2d) transmits at the reference position (top point). Here, as shown in an example in FIG. 10, the rotation position (rotation angle) of the transmitter 2d in the wheel 1 includes a point or a region (Null point) where the radio wave intensity received by the receiver 3 is lowest (in the case of the case). There are several). If the reference position (the highest point) at which the transmitter 2d transmits data is located near the null point, it is difficult for the receiver 3 to receive the transmitted data. Therefore, the rotation position (reference position) of the wheel 1 at the time of transmission of the TPMS sensor 2 (transmitter 2d) may not be specified on the vehicle body side. For this reason, there is a possibility that the wheel position of the TPMS sensor 2 cannot be accurately estimated in the auto-learning mode or the time until the estimation is completed may be increased. Here, in order to improve the reception probability, the data of the TPMS sensor 2 may be duplicated and transmitted from the transmitter 2d as a plurality of frames having the same content. However, a plurality of frames are transmitted at different rotational positions. For this reason, even if the data is simply duplicated, even if the reception probability is improved, it does not know at which rotational position the received frame was transmitted, and the reference for determining the wheel position of the TPMS sensor 2 The rotational position (the number of teeth) becomes inconvenient on the vehicle body side.

In contrast, in the first embodiment, the TPMS sensor 2 transmits a plurality of data (first to third frames) so as to include the rotational position information of itself (transmitter 2d). Specifically, as shown in FIG. 3 (b), the TPMS sensor 2 overlaps the TPMS data into a plurality of frames having the same contents (first to third frames), and each time TPMS data is transmitted. , One reference frame (first frame) is transmitted at a predetermined rotational position. That is, the first frame is transmitted at a predetermined rotational position (uppermost point), and the rotational position (uppermost point) of the TPMS sensor 2 at the time of transmission of the first frame is set as a reference position for wheel position determination. Further, the rotational position information of the transmitter 2d at the time of transmission of the frame is included in the other frames (second and third frames). Specifically, the first to third frames are transmitted at predetermined time intervals (100 msec, 140 msec) with frame numbers (1 to 3) indicating the transmission order of the frames. When any one of the first to third frames is received, the rotational position calculation unit 4a causes the TPMS sensor 2 to detect the first frame based on the frame number (1 to 3) and the time interval (100 msec, 140 msec). _Is estimated, that is, the number of teeth z _t2 is estimated.
In this way, by overlapping the data of the TPMS sensor 2 into a plurality of frames, even if the transmission position (top point) of the first frame is located near the Null point, other frames (second , The third frame) is received, the reception probability can be improved. The number of frames is not limited to 3, and may be 2 or 4 or more, for example. In addition, since each frame includes rotational position information (frame number), regardless of which of the plurality of frames is received, the rotational position (tooth) at the time of transmission of the transmitter 2d is determined on the vehicle body side based on the received information. The number z _t2 ) can be estimated. Therefore, it is possible to more accurately detect the rotational position of each wheel 1 at the time of transmission of the transmitter 2d on the vehicle body side, and to determine the wheel position of the TPMS sensor 2 with higher accuracy. Therefore, the auto learning mode can be completed early.

The TPMS sensor 2 transmits a reference frame (first frame) at a predetermined rotation position (top point), and the rotation position calculation unit 4a transmits transmission order information (frames, for example, a second frame). Number), the predetermined rotational position (the number of teeth z _t2 at the uppermost point) is estimated. In other words, the rotation position that serves as a reference for determining the wheel position of the TPMS sensor 2 on the vehicle body side is set to the rotation position (uppermost point) at which the TPMS sensor 2 outputs the first frame, and this reference rotation position ( The number of teeth z _t2 ) is calculated based on the other received frames (second and third frames). Therefore, the rotational position (the number of teeth z _t2 ) at the time of transmission of the TPMS sensor 2 can be estimated on the vehicle body side while simplifying the configuration of the TPMS sensor 2. That is, unlike Example 1, a means for estimating the rotational position of the TPMS sensor 2 at the time of transmission of each frame is provided on the wheel 1 (TPMS sensor 2) side, and the estimated rotational position is included for each frame. Transmission to the vehicle body side is also conceivable. On the other hand, in the first embodiment, without providing the estimation means as described above, the transmission position information (frame number) is included as rotation position information in each frame, thereby determining the wheel position of the TPMS sensor 2. The reference rotational position (the number of teeth z _t2 ) can be specified on the vehicle body side. Therefore, it is possible to simplify the configuration of the TPMS sensor 2 and reduce costs. The reference position for wheel position determination (calculation of dispersion characteristic value X) is not limited to the rotational position at which the first frame is transmitted, but the rotational position at which the second frame is transmitted or the rotational position at which the third frame is transmitted. It may be.

  Here, when the time interval for transmitting each frame is the same (for example, the transmission interval between the first and second frames and the transmission interval between the second and third frames are both 100 msec), each frame is transmitted. It is also conceivable that the rotational positions to be moved are all located near the same null point. For example, when the first transmission position is located near the null point and the rotation cycle of the wheel 1 and the transmission cycle of each frame are synchronized, the transmission position of each frame is changed every time the wheel 1 rotates. There is a possibility that none of the frames will be received because it coincides with the vicinity of the null point. In contrast, in the first embodiment, the transmitter transmits three or more frames (first to third frames), and transmits each frame at different time intervals (100 msec, 140 msec). Therefore, it is possible to suppress synchronization between the rotation cycle of the wheel 1 and the transmission cycle of each frame, thereby avoiding the above situation and improving the reception probability.

As the rotational position information of the transmitter 2d at the time of transmission of the frame included in each frame by the TPMS sensor 2, instead of the transmission order information (frame number), the rotational position of the transmitter 2d at the time of transmission of the frame is estimated. A value may be included. For example, when the sensor CU2c transmits each frame, the gravity acceleration-dependent component of the centrifugal acceleration detected by the G sensor 2b (the magnitude, sign, and change direction of the component sampled within each rotation period of the wheel 1) ) To calculate the rotational position (rotational angle) of the transmitter 2d and attach the rotational position to the frame to be transmitted. In this case, when any of the plurality of frames is received, the rotational position calculation unit 4a is the same as in the first embodiment (based on the above formula (1)), immediately before the reception start of the received frame and immediately after the reception is completed. The rotational position (number of teeth) at the time of transmission of the received frame is estimated based on the wheel speed pulse count value and the like that are input. The wheel position of the TPMS sensor 2 can be determined based on the correspondence between the estimated rotation position (number of teeth) and the rotation position (number of teeth converted from the rotation angle) included in the received frame. .
In the above determination, the dispersion characteristic value X as in the first embodiment may or may not be used. In addition, it is not necessary to provide a reference frame and transmit it at a predetermined rotational position (the highest point or the like), and each frame may be transmitted at an arbitrary rotational position. In other words, the rotational position of the TPMS sensor 2 at the time of transmission of each frame can be used as the reference position for determining the wheel position. The interval between frames (time interval or rotational position interval) need not be a predetermined value.
In the first embodiment, during the auto-learning mode, the TPMS sensor 2 of each wheel 1 waits for its rotational position to reach a predetermined position (the highest point, etc.) after 16 seconds from the previous TPMS data transmission time. The next TPMS data (reference frame) needs to be transmitted. On the other hand, in the above example in which the estimated value of the rotational position is included in each frame, TPMS data (arbitrary frame) can be transmitted at an arbitrary rotational position immediately after 16 seconds have elapsed since the previous transmission time. Therefore, during auto-learning mode, it is possible to obtain data for determining the wheel position of TPMS sensor 2 more quickly at each TPMS data transmission time, so the wheel position of TPMS sensor 2 can be determined earlier. can do.

Next, the effect will be described.
The tire pressure monitoring device of the first embodiment has the following effects.
(1) A tire air pressure monitoring device for monitoring the air pressure of each tire, which is mounted on the tire of each wheel 1 and provided on each wheel 1 with a tire air pressure detecting means (pressure sensor 2a) for detecting the tire air pressure. , A transmitter 2d that transmits air pressure information by radio signal and includes identification information (sensor ID) unique to each transmitter 2d in the radio signal, a receiver 3 that is provided on the vehicle body side and receives the radio signal, Corresponding to each wheel 1 is provided on the vehicle body side, and a rotational position detecting means (wheel speed sensor 8) for detecting the rotational position (wheel speed pulse) of each wheel 1 is provided on the vehicle body side, from the transmitter 2d. Based on the reception information (reception completion time t4) of the radio signal and the rotation position information (number of teeth z _t1 , z _t5 ) of the wheel 1 from the rotation position detection means (wheel speed sensor 8), transmission of the transmitter 2d when the vehicle body side to estimate the rotational position of the (transmission command time t2) (the number of teeth z _t2) Translocation estimation means and (rotational position calculation unit 4a), based on the estimated rotational position identification information included in the (number of teeth z _t2) and a radio signal (sensor ID), the transmitter 2d of the wheels 1 provided Wheel position determination means (wheel position determination unit 4c) for determining the position (FL to RR), and the transmitter 2d has a plurality of frames (first to third frames) by overlapping the radio signal, The frames are transmitted at intervals, and the rotational position information (frame number) of the transmitter 2d at the time of transmitting the frame is included in each frame.
Therefore, the reception probability can be improved and the wheel position of the transmitter 2d can be determined with higher accuracy.

(2) Each wheel 1 is provided with wheel side rotational position estimating means (G sensor 2b, sensor CU2c) for estimating the rotational position of the transmitter 2d at the time of transmission of each frame. The estimated rotational position may be included in each frame.
In this case, since it is only necessary to transmit each frame at an arbitrary rotational position, the wheel position of the transmitter 2d can be determined earlier.

(3) The transmitter 2d transmits a predetermined reference frame (for example, the first frame) among a plurality of frames (first to third frames) at a predetermined rotation position (top point), and transmits each frame to each other. Transmitting at predetermined intervals (time intervals of 100 msec, 140 msec), and including the transmission order information (frame number) of each frame as rotation position information, the vehicle side rotation position estimation means (rotation position calculation unit 4a) Estimates the predetermined rotation position (the number of teeth z _t2 at the highest point) based on the reception information (reception completion time t4 ′ and frame number) of a plurality of frames received (for example, the second frame) The wheel position determination means (wheel position determination unit 4c) determines the position (FL to RR) of the wheel 1 provided with the transmitter 2d based on the estimated predetermined rotation position (number of teeth z _t2 ). .
That is, transmission order information (frame number) attached to each frame (second and third frames) is combined with information of a predetermined interval (time interval 100 msec, 140 msec), and the frame (second and third frames) is combined. Represents rotational position information of the transmitter 2d at the time of frame transmission. Therefore, it is not necessary to provide each wheel 1 with means for estimating the rotational position of the transmitter 2d at the time of transmission of each frame, and the configuration can be simplified.

(4) The transmitter 2d transmits each frame (first to third frames) at predetermined time intervals (100 msec, 140 msec).
Accordingly, the vehicle body side rotational position estimating means (the rotational position calculation unit 4a) is configured to perform predetermined processing based on reception information (reception completion time t4 ′ and frame number) of a plurality of frames received (for example, the second frame). Can be estimated (the number of teeth z _t2 at the uppermost point).

(5) The transmitter 2d transmits three or more frames (first to third frames), and transmits each frame at different time intervals (100 msec, 140 msec).
Therefore, the reception probability can be further improved by suppressing the situation where the rotation period of the wheel 1 and the transmission period of each frame are synchronized and the transmission position of each frame coincides with the vicinity of the null point.

(6) The rotational position detection means (wheel speed sensor 8, ABSCU6) sends the rotational position information (wheel speed pulse count value) of the wheel 1 to the communication line (CAN communication line 7) at a predetermined time interval (cycle 20msec). The vehicle body side rotational position estimating means (rotational position computing unit 4a) outputs a communication line immediately before the reception start (time t2 ′) and immediately after reception completion (time t4 ′) of the received frame (for example, the second frame). (Rotation position (number of teeth) of wheel 1 input via CAN communication line 7), input time (t1 ', t5') of rotation position of wheel 1, and reception start time (time t3 ') or Based on the reception completion time (time t4 ′), the rotational position (the number of teeth z _t2 ) at the time of transmission of the transmitter 2d is estimated.
Therefore, it is possible to accurately estimate the wheel position of the TPMS sensor 2 while suppressing an increase in cost using an existing system.

(Example 2)
In the second embodiment, in the fixed position transmission mode, each TPMS sensor 2 transmits a plurality of data (for example, first to fourth frames) including the rotational position information of itself (transmitter 2d). As shown in FIG. 11, for each transmission of TPMS data, the TPMS sensor 2 transmits one frame (first frame) at a predetermined rotational position (reference position = top point), and each frame is mutually predetermined. Are transmitted at intervals (for example, 90 degrees). Further, the rotational position information of the transmitter 2d at the time of transmission of the frame is included in the other frames (second to fourth frames). Specifically, the TPMS sensor 2 includes transmission order information (frame number) of the frame in each frame. When any one of the first to fourth frames is received, the rotational position calculation unit 4a causes the TPMS sensor 2 to perform the first frame based on the frame number (1 to 4) and the rotational position interval (90 degrees). _Is estimated, that is, the number of teeth z _t2 is estimated.
For example, when the received frame is the third frame, the rotational position calculation unit 4a calculates the rotational position (the number of teeth) at which the third frame is transmitted by the same method as the above equation (1). The first frame is transmitted by subtracting the rotation position interval from the first frame to the third frame (number of teeth of the rotor corresponding to 90 degrees x 2 = 180 degrees) from this calculated rotation position (number of teeth). The predetermined rotation position (the number of teeth z _t2 ) is calculated.
Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

Therefore, as in the first embodiment, it is possible to accurately estimate the wheel position of the TPMS sensor 2 and improve the auto-learning mode at an early stage while improving the reception probability.
In order to improve the reception probability, the rotation position interval between frames may be varied or the number of frames may be increased.
In addition, the rotational position information included in each frame may include an estimated value (by the sensor CU2c) of the rotational position of the transmitter 2d at the time of transmission of the frame. In this case, the reference position for transmitting the first frame is not limited to a specific rotation position (top point).

The tire air pressure monitoring apparatus according to the second embodiment has the following effects.
(1) The transmitter 2d transmits each frame (first to fourth frames) at a predetermined rotational position interval (for example, 90 degrees).
Therefore, the transmission order information (frame number) attached to each frame (second and third frames) is combined with information of a predetermined rotation position interval (90 degrees) to combine the frames (second and third frames). ) Represents the rotational position information of the transmitter 2d at the time of transmission. For this reason, the vehicle body side rotational position estimating means (the rotational position calculation unit 4a) is based on the reception information (the reception completion time t4 ′ and the frame number) of a plurality of frames received (for example, the second frame), A predetermined rotational position (the number of teeth z _t2 at the uppermost point) can be estimated.

Example 3
In the third embodiment, in the fixed position transmission mode, each TPMS sensor 2 has a plurality of frames (for example, first to third frames) including the rotational position information of itself (transmitter 2d) for each transmission of TPMS data. Are transmitted in plural sets (for example, first to fourth sets). In the third embodiment, four groups are provided, and each group has first to third frames. Therefore, the total number of frames transmitted by the TPMS sensor 2 is 12 (= 4 × 3).
As shown in FIG. 12, the TPMS sensor 2 (transmitter 2d) has a plurality of (four) predetermined rotational positions (reference positions of each set) provided at a predetermined rotational position interval (for example, 90 degrees). Then, one frame (first frame) of the corresponding set is transmitted. Specifically, the sensor CU2c calculates the rotational position of the TPMS sensor 2 (transmitter 2d) based on the gravitational acceleration dependent component of the centrifugal acceleration detected by the G sensor 2b during the fixed position transmission mode. Send the first frame of the set at the highest point (0 degrees), send the first frame of the second set at the last point (90 degrees), and send the first frame of the third set at the lowest point (180 degrees) Transmit the fourth set of first frames at the forefront (270 degrees). TPMS sensor 2 transmits the first frame of each set at the reference position (top point, end point, bottom point, foremost point) of each set, and then the other frames (second and third frames) of the same set For example, in the same manner as in the first embodiment. That is, at predetermined time intervals (100 msec, 140 msec), frame numbers (2, 3) indicating the transmission order of the frames are attached, and the second and third frames are transmitted. Further, information (set number or flag corresponding to the reference position of each set) indicating which set the frame belongs to is attached to each frame.

For example, the TPMS sensor 2 transmits the second set of first frames at the second set of reference positions (90-degree last point), transmits the second frame after 100 msec, and transmits the third frame after 140 msec. To do. When any one of the first to third frames of the second set is received, the rotational position calculation unit 4a receives the above formula (1) based on the frame number (1 to 3) and the time interval (100 msec, 140 msec). In the same manner as in 1), the second set of reference positions (last point), that is, the number of teeth z _t2 is estimated. Further, the rotational position calculation unit 4a calculates the estimated second set reference position (the number of teeth at the last point) based on the set number assigned to the received frame, and sets the first set reference position (the highest point). Converted to the number of teeth z _t2 ). Specifically, by subtracting the number of teeth corresponding to the rotation position interval (90 degrees) between the first and second sets from the estimated number of teeth z _{t2 of} the second set reference position (last point), The number of teeth z _t2 of the first set of reference positions (top points) is calculated.
Similarly, when the frames of other groups (third and fourth groups) are received, the number of teeth z _t2 of the reference position (top point) of the first group is calculated. The dispersion calculating unit 4b calculates the dispersion characteristic value X of the calculated number of teeth z _t2 of the first set of reference positions (top points). That is, the wheel position of the TPMS sensor 2 is determined based on the calculated first set of reference positions (top points).
Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

Next, the operation will be described.
Null points are not limited to one place, and there may be multiple places. In this case, even if each frame is transmitted at different time intervals (100 msec, 140 msec) as in the first embodiment, the transmission position of all the frames depends on the rotation cycle (number of rotations) of the wheel 1, in other words, depending on the vehicle speed. May coincide with the vicinity of the (null) Null point and none of the frames are received. On the other hand, in the third embodiment, the configuration as described above can avoid the above situation. Therefore, while further improving the frame reception probability, the rotation position (number of teeth at the reference position of the first set) used as a reference for determining the wheel position of the TPMS sensor 2 is more reliably specified on the vehicle body side. can do.
Note that the dispersion characteristic value X of the number of teeth at the reference position may be calculated for each group. In Example 3, all the received data is converted into the first set of reference positions (the number of teeth at the uppermost point), so that a significant difference in the dispersion characteristic value X between the own wheel and the other wheel can be obtained more quickly. Can be put out. Therefore, the wheel position of the TPMS sensor 2 can be estimated with higher accuracy in a shorter time. The reference position for wheel position determination (calculation of dispersion characteristic value X) is not limited to the first set of reference positions (top point), but other sets (second set, etc.) of reference positions (last point, etc.) ).

As in the second embodiment, the TPMS sensor 2 (transmitter 2d) may transmit each set of frames (first to third frames) at a predetermined rotational position interval.
Further, the TPMS sensor 2 may be provided with a predetermined rotational position (reference position of each group) for transmitting the first frame for each group at a predetermined time interval. Also in this case, the number of teeth at the first set of reference positions (top points) can be calculated by subtracting the number of teeth for the predetermined time interval. In the third embodiment, the calculation positions can be simplified because the reference positions of the respective groups are provided at predetermined rotational position intervals.
In addition, the rotational position information included in each frame may include an estimated value (by the sensor CU2c) of the rotational position of the transmitter 2d at the time of transmission of the frame. In this case, the reference position for transmitting the first frame of each group is not limited to a specific rotation position (the highest point or the like).
Further, the number of sets is not limited to four, and may be other numbers such as 2, 3, 5, and the like.

The tire pressure monitoring device of the third embodiment has the following effects.
(1) Transmitter 2d transmits a plurality of sets (first to fourth sets) of a plurality of frames (first to third frames), and a predetermined set provided for each set at a predetermined interval (90 degrees). Each set of reference frames (for example, the first frame) is transmitted at the rotation position (the highest point, the last point, the lowest point, and the highest point).
Therefore, the reception probability can be further improved, and the rotational position (the number of teeth at the first set of reference positions) that serves as a determination criterion for the wheel position of the transmitter 2d can be more reliably specified.

(2) The transmitter 2d includes group information (group number) indicating which group the frame belongs to in each frame (first to third frames), and includes vehicle body side rotational position estimation means (rotational position calculation unit 4a). Is based on a predetermined rotation position (the number of teeth at the last point) of the group to which the frame estimated for the received frame belongs (for example, the second group) and the group information (group number). To the fourth set), a predetermined rotational position (the number of teeth at the uppermost point) of one predetermined reference set (for example, the first set) is estimated, and the wheel position determination means (wheel position determination unit 4c) is estimated The position of the wheel 1 provided with the transmitter 2d is determined based on a predetermined rotational position (the number of teeth z _t2 at the highest point) of the reference group (first group).
Therefore, by converting all the received data to the reference position (number of teeth z _t2 at the highest point) of one reference group (first group), the wheel position of the transmitter 2d can be accurately determined in a shorter time. Can be estimated.

[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 is shown in which a wheel speed sensor is used as the rotational position detecting means. However, in a vehicle equipped with an in-wheel motor as a drive source, the rotational angle may be detected using a motor resolver.

1 wheel
2a Pressure sensor (Tire pressure detection means)
2d transmitter
3 Receiver
4a Rotational position calculation unit (vehicle side rotational position estimation means)
4c Wheel position determination unit (wheel position determination means)
8 Wheel speed sensor (rotation position detection means)

Claims (8)

A tire pressure monitoring device for monitoring the pressure of each tire,
Tire pressure detecting means mounted on the tire of each wheel and detecting the air pressure of the tire;
A transmitter provided on each wheel, transmitting the air pressure information by a radio signal, and including identification information unique to each transmitter in the radio signal;
A receiver provided on the vehicle body side for receiving the radio signal;
Rotation position detecting means provided on the vehicle body side corresponding to each wheel, detecting the rotation position of each wheel, and outputting the rotation position information of the wheel at a predetermined time interval to a communication line ;
Estimated rotational position at the time of transmission of the transmitter based on reception information of the radio signal from the transmitter and rotational position information of the wheel input via the communication line provided on the vehicle body side Vehicle body side rotational position estimating means,
Wheel position determination means for determining the position of the wheel provided with the transmitter based on the estimated rotational position and the identification information included in the radio signal,
The transmitter overlaps the radio signal into a plurality of frames, transmits each frame at an interval, and includes the rotational position information of the transmitter at the time of transmission of the frame in each frame ,
The vehicle body side rotational position estimating means is
Based on the received information of the received one of the plurality of frames, estimate the rotational position at the time of transmission of the transmitter,
The rotational position of the wheel that is input via the communication line immediately before the start of reception of the received frame and immediately after the completion of reception, the input time of the rotational position of the wheel, and the reception start time or the reception completion time Based on the above , a tire air pressure monitor device that estimates a rotational position at the time of transmission of the transmitter . In the tire pressure monitoring device according to claim 1,
Each wheel is provided with a wheel side rotational position estimating means for estimating the rotational position of the transmitter at the time of transmission of each frame,
The transmitter includes the estimated rotational position in each frame as the rotational position information. In the tire pressure monitoring device according to claim 1,
The transmitter transmits a predetermined one reference frame among the plurality of frames at a predetermined rotational position, transmits each frame at a predetermined interval, and transmits the frame to each frame as the rotational position information. Including transmission order information for
The vehicle body side rotational position estimating means estimates the predetermined rotational position based on reception information of the received one of the plurality of frames;
The wheel position determination means determines a position of a wheel provided with the transmitter based on the estimated predetermined rotational position. In the tire pressure monitoring device according to claim 3,
The tire pressure monitoring device, wherein the transmitter transmits each frame at a predetermined time interval. In the tire pressure monitoring device according to claim 4,
The tire pressure monitoring apparatus, wherein the transmitter transmits three or more frames and transmits each frame at different time intervals. In the tire pressure monitoring device according to claim 3,
The tire pressure monitoring device, wherein the transmitter transmits each frame at a predetermined rotational position interval. A tire pressure monitoring device for monitoring the pressure of each tire,
Tire pressure detecting means mounted on the tire of each wheel and detecting the air pressure of the tire;
A transmitter provided on each wheel, transmitting the air pressure information by a radio signal, and including identification information unique to each transmitter in the radio signal;
A receiver provided on the vehicle body side for receiving the radio signal;
Rotation position detecting means provided on the vehicle body side corresponding to each wheel, detecting the rotation position of each wheel, and outputting the rotation position information of the wheel at a predetermined time interval to a communication line;
Estimated rotational position at the time of transmission of the transmitter based on reception information of the radio signal from the transmitter and rotational position information of the wheel input via the communication line provided on the vehicle body side Vehicle body side rotational position estimating means,
Wheel position determination means for determining the position of the wheel provided with the transmitter based on the estimated rotational position and the identification information included in the radio signal,
The transmitter overlaps the radio signal into a plurality of frames, transmits a predetermined reference frame of the plurality of frames at a predetermined rotational position, and transmits each frame at a predetermined interval. , Including transmission order information of the frames as rotational position information of the transmitter at the time of transmission of the frames in each frame,
The vehicle body side rotational position estimating means estimates the predetermined rotational position based on reception information of the received one of the plurality of frames;
The wheel position determination means determines a position of a wheel provided with the transmitter based on the estimated predetermined rotational position,
The transmitter of the plurality of frames and a plurality of sets transmission, tire air pressure monitoring system and transmits the reference frame of each set at the predetermined rotational position which is provided for each set with a predetermined gap . In the tire pressure monitoring device according to claim 7,
The transmitter includes set information indicating which set the frame belongs to in each frame,
The vehicle body side rotational position estimating means is configured to determine the predetermined reference group of the predetermined one of the plurality of sets based on the predetermined rotational position of the set to which the frame estimated for the received frame belongs and the set information. Estimate the rotational position of
The tire pressure monitoring device, wherein the wheel position determination means determines a position of a wheel provided with the transmitter based on the estimated rotation position of the estimated reference set.

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