JP2015042503A - Wheel information acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce time required for determination processing for determining a position of a wheel of a sensor unit.SOLUTION: A four-wheel ID determination part 54 stores a pulse signal outputted at a rotation position where a pitch error of a magnetic rotor disposed on a wheel speed sensor 60 becomes maximum as a pulse number 1, and increments the pulse number for every pulse signal input. Therefore the pulse number indicates an absolute rotation position of the wheel. A sensor unit 10 transmits a radio signal at a constant turning position. The four-wheel ID determination part 54 performs sampling of the pulse numbers of four wheels as it receives the sensor ID, and registers the wheel position of the wheel speed sensor 60 where variation of the pulse number becomes minimum as the wheel position of the sensor ID.

Description

  The present invention includes a wheel sensor fixed to a wheel and a vehicle body side device fixed to the vehicle body, and transmits a wheel state quantity such as tire air pressure from the wheel sensor to the vehicle body side device by a radio signal. The present invention relates to a wheel information acquisition device that acquires wheel information with a device.

  2. Description of the Related Art Conventionally, as an example of a wheel information acquisition device, a tire pressure monitoring device that notifies a driver of tire pressure information is known. The tire pressure monitoring device includes a tire pressure sensor unit (referred to as a wheel sensor) that detects tire pressure for each wheel, transmits tire pressure information from the wheel sensor by radio signals, and transmits the radio signals to the vehicle body side device. And tire pressure information is acquired. When it is determined that the tire air pressure is decreasing based on the received tire air pressure information, the vehicle body side device displays a message to that effect and notifies the driver.

  In such a tire pressure monitoring device, in order to determine from which wheel sensor the radio signal received by the vehicle body side device is transmitted, the radio signal includes the identification of the wheel sensor in addition to the tire pressure information. The sensor ID which is information is included. The sensor ID is registered in advance in the vehicle body side device in association with the wheel position where the wheel sensor is provided. Therefore, tire pressure information can be acquired separately for each wheel.

  However, when tire rotation is performed or wheels are replaced with other ones, the sensor ID registration status is different from the actual one. With respect to such a problem, the device proposed in Patent Document 1 has a configuration for automatically determining the wheel position of each wheel sensor. In this device, an acceleration sensor is incorporated in the wheel sensor, the rotation angle of the wheel is detected by the acceleration in the rotation direction of the wheel detected by the acceleration sensor, and the tire air pressure is detected at the timing when the rotation direction acceleration becomes the vertical direction. And a wireless signal including the rotation angle of the wheel and the sensor ID is transmitted. On the other hand, the vehicle body side device is configured to detect the rotation angle of each wheel based on the count value of the pulse signal output from the wheel speed sensor, and the pulse output from each wheel speed sensor when a radio signal is received from the wheel sensor. The count value of the signal is stored as an initial value. And every time a radio signal is received from a wheel sensor during driving | running | working, the count value of the pulse signal which each wheel speed sensor outputs is sampled. The vehicle body side device compares the sampled count value with the initial value, excludes the wheel position of the wheel speed sensor whose deviation between the count value and the initial value exceeds the allowable value, and determines the last remaining wheel position. It is determined as the wheel position of the wheel sensor.

JP 2010-1222023 A

  In the apparatus proposed in the above-mentioned Patent Document 1, the rotation angle of the wheel from that time point is detected by counting the number of pulse signals output from the wheel speed sensor after the arbitrarily set time point. For this reason, the rotational position of the wheel detects the relative position with respect to the position where the counting is started. If the vehicle stops while the wheel position determination process of the wheel sensor is being performed, the pulse signal is not output from the wheel speed sensor, so the determination process is interrupted.

  However, when the vehicle is stopped, chattering noise may occur in the output of the wheel speed sensor due to passengers getting on and off or engine vibration. In that case, noise is counted, and the count value does not correspond to the rotation angle of the wheel. Therefore, in the conventional apparatus, when the vehicle stops, after the vehicle starts running, the count value of the pulse signal is reset and the count value of the pulse signal is sampled again from the beginning. That is, in the conventional device, the rotational position of the wheel represents a relative position with respect to the position where the counting of the pulse signal is started, so when the count value has increased due to chattering noise during stopping, The relationship between the count value and the relative position is shifted. For this reason, the count value sampled before stopping cannot be used. Therefore, it is necessary to repeat the sampling of the count value of the pulse signal from the beginning, and it takes a long time to complete the wheel position determination process.

  An object of the present invention is to cope with the above-described problem, and is to shorten the time for determining the wheel position of the wheel sensor.

In order to achieve the above object, the present invention is characterized in that it is fixed to each wheel of a vehicle, detects a wheel state quantity, and transmits the detected wheel state quantity together with a sensor ID by a radio signal. A wheel sensor (10) is provided fixed to the vehicle body, receives a radio signal transmitted from the wheel sensor, acquires a wheel state quantity for each registered sensor ID, and according to the wheel state quantity In the wheel information acquisition device including the vehicle body side device (50) that performs processing,
Each wheel sensor is configured to transmit a wireless signal including sensor turning position information representing a sensor turning position that is a turning position around its own axle,
The vehicle body side device is:
It is provided on the vehicle body side corresponding to each wheel, and outputs a pulse signal every time the wheel rotates by a predetermined angle, and only when the rotation position of the wheel passes a specific rotation position that is always constant with respect to the vehicle body, Vehicle body side rotation signal output means (60) for changing the output state of the pulse signal;
Vehicle body side rotational position detecting means (S11 to S15) for detecting the rotational position of each wheel based on the specific rotational position based on the pulse signal output by the vehicle body side rotational signal output means;
A wheel sensor is provided for each wheel sensor based on the relationship between the sensor turning position when the wireless signal transmitted by the wheel sensor is received and the rotational position of each wheel detected by the vehicle body side rotational position detecting means. Sensor wheel position determining means (S17 to S20, S17 to S201) for determining the determined wheel position;
There is a sensor wheel position registration means (53) in which the sensor ID of the wheel sensor from which the wheel position is determined is registered as the sensor ID of the wheel position.

  The present invention includes a wheel sensor fixed to each wheel and a vehicle body side device fixed to the vehicle body. The wheel sensor detects the wheel state quantity and transmits the detected wheel state quantity together with the sensor ID by a radio signal. For example, the wheel sensor includes a tire air pressure sensor that detects tire air pressure, and transmits information representing the detected tire air pressure together with the sensor ID by a radio signal. The sensor ID is identification information that identifies the wheel sensor. The vehicle body side device receives the radio signal transmitted from the wheel sensor, acquires the wheel state quantity detected by the wheel sensor specified by the registered sensor ID, and performs processing according to the wheel state quantity. For example, notification processing of tire pressure information is performed.

  The wheel sensor turns around the axle as the wheel rotates. Each wheel sensor transmits a radio signal including sensor turning position information representing a sensor turning position that is a turning position around its own axle. The sensor turning position information is not limited to the information representing the turning position of the wheel sensor by the rotation angle, and for example, by configuring the wheel sensor to transmit a wireless signal at a timing at which the turning position is set in advance, Wireless signal transmission timing information can also be used as sensor turning position information.

  When managing the wheel information for each wheel position, it is necessary to register the relationship between the sensor ID of the wheel sensor and the wheel position. However, tire rotation is performed or the wheel is replaced with another one. In this case, the sensor ID registration status is different from the actual one. In order to cope with such a situation, the vehicle body side device includes vehicle body side rotation signal output means, vehicle body side rotation position detection means, sensor wheel position determination means, and sensor wheel position registration means.

  The vehicle body side rotation signal output means is provided on the vehicle body side corresponding to each wheel, and outputs a pulse signal every time the wheel rotates by a predetermined angle. The output state of this pulse signal changes only when the wheel passes through a specific rotational position where the rotational position of the wheel is always constant with respect to the vehicle body. That is, the vehicle body side rotation signal output means outputs a pulse signal whose output state is different between when the rotation position of the wheel passes the specific rotation position and when the wheel does not pass the specific rotation position. Therefore, it is possible to detect that the rotational position of the wheel has passed the specific rotational position by detecting a change in the output state of the pulse signal.

  The vehicle body side rotational position detecting means detects the rotational position of each wheel based on the specific rotational position based on the pulse signal output by the vehicle body side rotational signal output means. The pulse signal is output every time the wheel rotates by a predetermined angle. For this reason, the rotational position of the wheel can be detected from the number of output pulse signals after the rotational position of the wheel has passed the specific rotational position. The specific rotation position represents a rotation position that is always constant with respect to the vehicle body. Therefore, the rotational position of each wheel detected by the vehicle body side rotational position detecting means represents the absolute rotational position.

  The vehicle body side rotational position detection means detects the rotational position of each wheel, but the positional relationship between the rotational position of one of the wheels and the sensor turning position of one wheel sensor should always be constant. That is, the rotational position of the wheel detected with respect to the common wheel (the same wheel) and the sensor turning position always have a certain relationship. On the other hand, the relationship between the rotational position of one wheel and the sensor turning positions of the remaining wheel sensors varies during traveling. That is, the rotation position of the wheel detected with respect to the non-common wheel (different wheel) and the sensor turning position do not have a fixed relationship.

  By utilizing this, the sensor wheel position determining means is based on the relationship between the sensor turning position when the wireless signal transmitted from the wheel sensor is received and the rotational position of each wheel detected by the vehicle body side rotational position detecting means. The wheel position at which the wheel sensor is provided is determined for each wheel sensor. The sensor ID of the wheel sensor from which the wheel position is determined is registered in the sensor wheel position registration unit as the sensor ID of the wheel position. In this case, since the wheel rotation position and the sensor turning position represent the absolute rotation position around the axle, the wheel position provided with the wheel sensor can be determined in a short time.

  For example, if the sensor wheel position determination means is configured to determine the wheel position of the wheel sensor based on the transition of the relationship between the sensor turning position and the wheel rotation position, the vehicle is traveling. Even when the vehicle stops in the middle of the discrimination process, data representing the relationship between the sensor turning position detected before stopping and the rotational position of the wheel can be used. Therefore, after the start of traveling, it is only necessary to acquire the shortage of data representing the relationship between the sensor turning position and the wheel rotation position. For this reason, the time required to discriminate the wheel position where the wheel sensor is provided can be shortened.

  In addition, a configuration is adopted in which the wheel position of the wheel sensor is uniquely determined from the relationship between the sensor turning position and the wheel rotation position without detecting the transition of the relationship between the sensor turning position and the wheel rotation position. You can also. In this case, the time required for discriminating the wheel position where the wheel sensor is provided can be further shortened.

Another feature of the present invention is that the pulse signal output from the vehicle body side rotation signal output means is uniform in the rotation angle interval at which the pulse signal is output only when the rotation position of the wheel passes the specific rotation position. The degree is reduced,
The vehicle body side rotational position detecting means obtains a specific rotational position at which the degree of uniformity of the rotational angle interval at which the pulse signal is output is reduced by calculation, and detects the rotational position of each wheel based on the specific rotational position. (S12 to S14)

  In the present invention, only when the rotational position of the wheel passes the specific rotational position, the degree of uniformity of the rotational angle interval of the pulse signal output from the vehicle body side rotational signal output means decreases. That is, when the rotational position of the wheel passes through the specific rotational position, the degree of uniformity of the rotational angle interval at which the pulse signal is output is lower than when the wheel does not pass through the specific rotational position. Accordingly, the specific rotation position can be obtained by calculating the degree of uniformity of the rotation angle interval for each pulse signal. The vehicle body side rotational position detecting means obtains a specific rotational position where the degree of uniformity of the rotational angle interval from which the pulse signal is output is reduced by calculation, and detects the rotational position of each wheel based on this specific rotational position. Thereby, the absolute rotational position of the wheel can be detected.

In another feature of the present invention, the vehicle body side rotation signal output means includes a magnetic rotor (70) provided with a magnetized ring plate (72) having magnetic poles formed at equal intervals in the circumferential direction so as to be rotatable integrally with a wheel. And an encoder (60) having a magnetic detector (80) that is fixed to a vehicle body and detects the magnetism of the magnetized ring plate and outputs the pulse signal as the magnetic rotor rotates.
In the manufacturing process of the magnetized ring plate, the connecting portion (A) in which both ends of the base material of the magnetized ring plate are connected to each other becomes a portion where the degree of uniformity of the rotation angle interval at which the pulse signal is output decreases. There is.

  The present invention includes an encoder having a magnetic rotor and a magnetic detector as vehicle body side rotation signal output means. The magnetic rotor includes a magnetized ring plate having magnetic poles formed at equal intervals in the circumferential direction so as to be rotatable integrally with the wheel. The magnetic detector is fixed to the vehicle body, detects the magnetism of the magnetized ring plate, and outputs a pulse signal along with the rotation of the magnetic rotor. In the magnetized ring plate, in the manufacturing process, the base material is rolled into a ring shape, and both ends of the base material are connected. It is difficult to magnetize the connected portions with higher accuracy than the other portions, and the degree of uniformity of the rotation angle interval at which the pulse signal is output decreases. In the present invention, focusing on the fact that the magnetization accuracy is lowered at the connecting portion, the rotational position of the wheel detected by the magnetic detector by the connecting portion is set as the specific rotational position. Therefore, the output state of the pulse signal can be changed at the specific rotational position without newly providing a special member.

Another feature of the present invention is that each wheel sensor transmits a radio signal at a timing at which a turning position about its own axle becomes a preset setting position, so that the sensor turning position information is transmitted to the vehicle body side device. Is to provide
The sensor wheel position discriminating means is provided with a wheel sensor for each wheel sensor based on the rotational position of each wheel detected by the vehicle body side rotational position detecting means when the wireless signal transmitted from the wheel sensor is received. The wheel position is determined.

  In the present invention, each wheel sensor transmits a radio signal at a timing at which the turning position around its own axle becomes a preset position. For this reason, the transmission timing of a radio | wireless signal can be utilized as information showing the turning position of a wheel sensor. For example, the wheel sensor is provided with an acceleration sensor for detecting the acceleration in the direction of the centrifugal force or the circumferential direction of the wheel, and the turning position around its own axle is determined in advance from the transition of the gravitational acceleration component of the acceleration detected by this acceleration sensor. Get the timing for the set position. Therefore, the rotational position of the wheel detected by the vehicle body side rotational position detection means when receiving the radio signal transmitted by the wheel sensor is always constant only for the wheel to which the wheel sensor is attached. For this reason, it is possible to easily determine the wheel position where the wheel sensor is provided.

  Another feature of the present invention is that the rotational position detected by the vehicle body side rotational position detection means when receiving the radio signal transmitted by the wheel sensor, regardless of the phase of the wheel attached to the vehicle body. Is that the encoder is assembled at a position where the wheel is not the same between the wheels.

  For example, in the case of a four-hole fastening type in which the wheel is fastened to the hub with four bolts, the wheel can be fastened to the vehicle body (hub) in four different phases (rotational positions). In the present invention, the rotational position detected by the vehicle body side rotational position detecting means when receiving the wireless signal transmitted by the wheel sensor is not the same between the wheels, regardless of the phase of the wheel attached to the vehicle body. An encoder is assembled at the position. For example, the rotational position of the wheel detected by the vehicle body side rotational position detection means when receiving the radio signal transmitted by the wheel sensor is not the same among all the wheels, and the angle of the rotational position between the wheels. The encoder assembly position may be set so that the difference does not become an integral multiple of an angle obtained by dividing 360 deg by the number of fastening bolts (number of fastening holes).

  Thus, according to the present invention, the rotation position of the wheel when the sensor turning position becomes the set position, that is, the wheel sensor transmits, without detecting the transition of the relationship between the sensor turning position and the wheel rotation position. The wheel position of the wheel sensor can be uniquely determined from the rotational position of the wheel when the wireless signal to be received is received. Therefore, it is possible to further reduce the time required for determining the wheel position where the wheel sensor is provided.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiment in parentheses, but each constituent element of the invention is the reference numeral. It is not limited to the embodiment defined by.

It is a schematic block diagram of the wheel information acquisition apparatus which concerns on embodiment of this invention. It is a functional block diagram in a sensor unit and wheel ECU. It is a flowchart showing a sensor ID registration routine. It is a figure showing the image of the pulse number memorize | stored in a pulse number memory | storage part. It is a figure showing the image about the change of a pulse number. It is the schematic showing the side and front of an encoder. It is a manufacturing process figure of a magnetized ring board. It is a wave form diagram of the pulse signal which a wheel speed sensor outputs. It is a figure showing the display screen which an alarm device displays. It is a flowchart showing the sensor ID registration routine of a modification.

  Hereinafter, a vehicle wheel information acquisition apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a wheel information acquisition device used in a tire pressure monitoring system (TPMS). The wheel information acquisition device is a device for notifying a driver of tire pressure information, and is fixed to a vehicle body B and a tire pressure sensor unit 10 (hereinafter referred to as a sensor unit 10) fixed to each wheel W. The wheel state information processing unit 50 (hereinafter referred to as the wheel ECU 50) and the alarm 100 are provided. FIG. 2 is a functional block diagram of the sensor unit 10 and the wheel ECU 50. Since all the sensor units 10 provided in each wheel W have the same function, only one of them is shown in FIG.

  The sensor unit 10 is attached to the tire air injection valve of the wheel W. The sensor unit 10 includes an air pressure sensor 11, a temperature sensor 12, an acceleration sensor 13, a control unit 20, an antenna 14, and a battery 15. The air pressure sensor 11 detects the air pressure of the tire and outputs a detection signal representing the air pressure P to the control unit 20. The temperature sensor 12 detects the tire temperature and outputs a detection signal representing the tire temperature T to the control unit 20. The acceleration sensor 13 detects the acceleration of the wheel W in the centrifugal force direction and outputs a detection signal representing the acceleration G to the control unit 20.

  The control unit 20 includes a microcomputer and a communication circuit as main parts, and paying attention to its function, the timing setting unit 21 that sets the timing for transmitting a wireless signal, and the ID storage that stores the sensor ID that is identification information of the sensor unit 10 Unit 22 includes a transmission processing unit 23 that generates a radio signal and transmits it via the antenna 14.

  The timing setting unit 21 sets the transmission timing of the radio signal based on the acceleration G detected by the acceleration sensor 13 and the transmission time interval. Since the sensor unit 10 including the acceleration sensor 13 also turns around the axle when the wheel W is rotating, the output of the acceleration sensor 13 is a pulsation waveform with one rotation of the wheel W taken as one cycle with the addition of gravitational acceleration. become. For this reason, the timing at which the sensor unit 10 becomes the uppermost point or the lowermost point of the wheel W can be detected by extracting the pulsation of the acceleration G. Therefore, the timing setting unit 21 sets the timing at which the turning position of the sensor unit 10 is the highest point (may be the lowest point) as the wireless signal transmission timing based on the acceleration G.

  If the transmission timing of the radio signal is simply set based on the turning position of the sensor unit 10, the transmission interval during traveling is shortened, so the transmission time interval is equal to or longer than a predetermined time (for example, 1 minute). A transmission time interval condition is added. In other words, the timing at which the elapsed time since the last transmission of the wireless signal is equal to or longer than the predetermined time and the turning position of the sensor unit 10 is the set position (in this example, the highest point) is the transmission timing of the wireless signal. Set to.

  The timing setting unit 21 includes a timekeeping timer, and measures an elapsed time since the wireless signal was transmitted immediately before. Then, based on the measured timer value and the change in the acceleration G detected by the acceleration sensor 13, the transmission timing of the radio signal is set as described above, and the transmission command is transmitted when the transmission timing arrives. To the unit 23. In this embodiment, the acceleration sensor 13 detects the acceleration G in the centrifugal force direction of the wheel W, but may detect the circumferential acceleration of the wheel W instead. In that case, the timing at which the turning position of the sensor unit 10 becomes the foremost point and the rearmost point (intermediate position between the uppermost point and the lowermost point) of the wheel W can also be detected based on the pulsation of the acceleration G. Therefore, the timing setting unit 21 can set the transmission timing according to the direction of acceleration detected by the acceleration sensor 13.

  When the transmission processing unit 23 receives a transmission command from the timing setting unit 21, the air pressure P output from the air pressure sensor 11, the tire temperature T output from the temperature sensor 12, and the sensor ID stored in the ID storage unit 22. Is generated, transmission data in which the sensor ID is added to the air pressure P and the tire temperature T is generated, and a radio signal obtained by modulating the transmission data is transmitted via the antenna 14. The air pressure P and the tire temperature T are the latest information when transmitting a radio signal.

  The battery 15 supplies power to each electric load in the sensor unit 10.

  The sensor unit 10 of the present embodiment can only transmit to the wheel ECU 50 (incapable of bidirectional communication), and unilaterally transmits the radio signal at the above-described cycle.

  Next, the wheel ECU 50 will be described. The wheel ECU 50 includes a microcomputer and a communication circuit as main parts. Focusing on the functions, the wheel ECU 50 includes a reception processing unit 51, a data processing unit 52, a registration ID storage unit 53, a four-wheel ID determination unit 54, and a pulse number storage unit 55. ing. Moreover, the wheel ECU 50 is connected to the alarm device 100 provided near the driver's seat.

  The reception processing unit 51 connects the antenna 90 and receives a radio signal transmitted from each sensor unit 10 via the antenna 90. Each time the reception processing unit 51 receives a wireless signal, the reception processing unit 51 extracts data representing the sensor ID, the air pressure P, and the tire temperature T from the wireless signal and outputs the data to the data processing unit 52. In addition, the reception processing unit 51 outputs data representing the sensor ID to the four-wheel ID determination unit 54 at the timing when the wireless signal is received from the sensor unit 10.

  The data processing unit 52 creates air pressure information at each wheel position based on the data input from the reception processing unit 51 and the sensor IDs of the four wheels stored in the registration ID storage unit 53.

  The registration ID storage unit 53 is a nonvolatile memory that stores the sensor ID of the sensor unit 10 attached to the wheel W of the host vehicle for each wheel position. The registration ID storage unit 53 stores a left front wheel ID storage area 53FL that stores a sensor ID provided in the sensor unit 10 for the left front wheel, and a right front wheel ID storage area that stores a sensor ID provided in the sensor unit 10 for the right front wheel. 53FR, a left rear wheel ID storage area 53RL for storing the sensor ID provided in the sensor unit 10 for the left rear wheel, and a right rear wheel ID storage area for storing the sensor ID provided for the sensor unit 10 for the right rear wheel 53RR. Hereinafter, the sensor ID stored in the registered ID storage unit 53 is referred to as a registered sensor ID.

  The data processing unit 52 refers to the correspondence relationship between the registration sensor ID stored in the registration ID storage unit 53 and the wheel position, and determines the four-wheel air pressure P as the wheel position based on the data input from the reception processing unit 51. Separately generated notification data is generated, and the generated notification data is output to the notification device 100. Further, the air pressure P is compared with the appropriate judgment value Pref for each wheel, and if the air pressure P is lower than the proper judgment value Pref, the air pressure insufficient wheel position data specifying the wheel position where the air pressure is insufficient is sent to the alarm device 100. Output.

  The data processing unit 52 also determines whether or not the tire temperature T is abnormally high based on the input tire temperature T, and if a tire overheating state is detected, the data processing unit 52 displays tire overheating information. Output to other vehicle control device (not shown). Further, a warning display command may be output to the alarm device 100. Further, the appropriateness determination value Pref for determining the appropriateness of the tire pressure may be corrected based on the tire temperature T.

  The alarm device 100 includes, for example, a display provided at a position visible from the driver's seat, a display driver that drives the display, and a display microcomputer that controls the display driver, and according to the notification data output from the data processing unit 52. The tire pressure monitor screen is displayed on the display.

  FIG. 9 shows a tire pressure monitor screen D displayed on the display of the alarm device 100. The tire pressure monitor screen D includes a vehicle body mark M1 that represents a plan pattern of the vehicle body, a pneumatic pressure value display M2 that is provided next to each wheel position and displays the tire air pressure numerically, and a warning mark that alerts the driver. M3 is displayed. Based on the notification data input from the data processing unit 52, the alarm device 100 displays the air pressure numerically on the air pressure numerical value display unit M2. On the basis of the insufficient air pressure wheel position data, when the air pressure is insufficient, the display of the numerical value display unit M2 of the wheel position is reversed and the warning mark M3 is turned on. The warning mark M3 is visible to the driver only when it is lit, and is not visible to the driver when it is unlit. Accordingly, the driver can recognize which wheel has insufficient air pressure along with the air pressure value.

  The registered sensor ID stored in the registered ID storage unit 53 is correct at the time of shipment of the vehicle. Thereafter, when the tire is rotated or the wheel W is replaced with another one. The registration status stored in the registration ID storage unit 53 is different from the actual one. Further, the sensor unit 10 may be replaced due to a failure or the like.

  In order to deal with such a situation, the wheel ECU 50 is provided with a four-wheel ID determination unit 54 and a pulse number storage unit 55.

  The four-wheel ID discriminating unit 54 is a sensor unit that is identified by a sensor ID included in a radio signal, which wheel W the radio signal received by the reception processing unit 51 is transmitted from. It is a functional unit that automatically determines which wheel W is attached to 10 by estimation, and identifies the wheel position in the registered ID storage unit 53 and registers the sensor ID based on the determination result. The pulse number storage unit 55 is a non-volatile memory that temporarily stores a pulse number (to be described later) required for the arithmetic processing when the four-wheel ID determination unit 54 automatically determines the sensor ID.

  The four-wheel ID discriminating unit 54 is connected to a wheel speed sensor 60 for detecting the rotational speed of the wheel W. The four-wheel ID determination unit 54 receives a pulse signal output from the wheel speed sensor 60 and detects the rotational position of the wheel W based on the pulse signal. And based on the count value of the pulse signal which the wheel speed sensor 60 outputs in the timing which received the radio signal transmitted from the sensor unit 10, the sensor unit 10 (sensor ID) which transmitted the radio signal is specified. In the conventional apparatus, based on the count value of the pulse signal output from an arbitrary time point, the relative rotational position where the wheel W has rotated from the arbitrary time point is obtained. On the other hand, in the present embodiment, the specific rotation position of the wheel W relative to the vehicle body B (a fixed position that does not vary) is used as a reference after the rotation position of the wheel W passes the specific rotation position (the specific rotation position and Counts the output pulse signal (after matching). Therefore, this count value represents the absolute rotational position of the wheel W.

  As shown in FIG. 6, the wheel speed sensor 60 is configured by an encoder having a magnetic rotor 70 built in and fixed to a hub and a magnetic detector 80 that faces the magnetic rotor 70 and is fixed to the vehicle body so as not to rotate. Yes. The magnetic rotor 70 includes a ring-shaped washer 71 that rotates integrally coaxially with the hub, and a magnetized ring plate 72 that is fixed to the washer 71. The magnetized ring plate 72 is formed by forming a synthetic rubber (for example, NBR) material mixed with a magnetic material into a ring plate shape having a thickness of about 1 mm, and the N pole and the S pole are in the circumferential direction. Are formed alternately.

  FIG. 7 shows a process in which the magnetized ring plate 72 is manufactured. The magnetized ring plate 72 is manufactured by processing a rod body in which a synthetic rubber material mixed with a magnetic material is formed into a rod shape (FIG. 7: a). The material from which the magnetized ring plate 72 is manufactured is called a base material. The rod-shaped base material 720 is rounded so as to form a ring shape, and both ends thereof are connected to face each other and processed into a ring shape (FIG. 7: b, c). Then, by pressing the ring-shaped base material 721 connected in a ring shape in a direction perpendicular to the ring surface, a ring plate 722 having a thickness of about 1 mm is formed (FIG. 7: d). Then, the ring plate 722 is set in a magnetizing device (not shown) and magnetized on the ring plate 722 (FIG. 7: e). In the present embodiment, 48 N poles and S poles are alternately formed in the circumferential direction.

  In the magnetized ring plate 72 manufactured in this way, a deviation occurs in the magnetization orientation at the connecting portion A where both ends of the base material are connected. The magnetic detector 80 detects the magnetism of the rotating magnetized ring plate 72 and outputs a pulse signal as shown in FIG. 8, but in this connection A, the pulse signal is smaller than in other places. The accuracy (uniformity) of the output rotation angle interval θpitch (interval at which the pulse signal is output with respect to the rotation angle) decreases. In order to accurately detect the wheel speed, it is ideal that a pulse signal is output from the magnetic detector 80 at an equal pitch with respect to the rotation angle of the magnetic rotor 70. However, due to the above manufacturing reasons, a portion where the pitch accuracy is lowered occurs in the connecting portion A.

  In this embodiment, since 48 magnetic poles (magnetic poles having a pair of N pole and S pole) are formed on the magnetized ring plate 72, the magnetic rotor 70 rotates 7.5 deg (360 deg / 48). Each time, a pulse signal is output from the magnetic detector 80. In this case, for example, the pitch accuracy of the magnetized ring plate 72 is about ± 1% for one magnetic pole serving as the connecting portion A and about ± 0.5% for the other magnetic pole.

  Thus, in the present embodiment, the rotational position of the wheel W relative to the specific rotational position is detected with the rotational position of the wheel W from which the connecting portion A is detected as the specific rotational position. Since the magnetic rotor 70 is fixed to the hub so as to be integrally rotatable, and the magnetic detector 80 is fixed to the vehicle body so as not to rotate, the specific rotational position is always a constant wheel rotational position. For this reason, the rotational position of the wheel W with respect to the specific rotational position can be handled as the absolute rotational position of the wheel W. The absolute rotation position of the wheel W can be expressed as a wheel rotation position with respect to the vehicle body or a wheel rotation position with respect to the ground plane.

  In calculating the wheel speed, the pitch error is corrected. For this reason, in the brake control such as ABS, the wheel speed is calculated based on the interval of the pulse signal after the pitch error is corrected. Therefore, the pitch error is not a problem.

  A process performed by the four-wheel ID determination unit 54 will be described. FIG. 3 illustrates a four-wheel ID determination routine performed by the four-wheel ID determination unit 54. The four-wheel ID determining unit 54 executes a four-wheel ID determining routine when the ignition switch is turned on. The four-wheel ID discriminating routine is roughly classified into detection processing (S1 to S14) of a position where the pitch accuracy of the magnetized ring plate 72 is lowered, and sampling of a pulse number when a radio signal is transmitted from the sensor unit 10. It consists of processing (S15 to S19), sensor ID wheel position determination processing (S20) based on the transition of the pulse number, and sensor ID registration processing (S21 to S22).

  When the four-wheel ID determination routine is activated, the four-wheel ID determination unit 54 determines whether or not the vehicle is traveling in step S11. In the present embodiment, it is determined that the vehicle is traveling when the vehicle speed is equal to or higher than a set speed (for example, 20 km / h). The four-wheel ID determination unit 54 acquires vehicle speed information from a CAN communication line or a vehicle speed sensor (not shown), and determines whether or not the vehicle is traveling by comparing the current vehicle speed with the set vehicle speed. The four-wheel ID discriminating unit 54 waits until the vehicle speed condition is satisfied. When the vehicle speed condition is satisfied, the four-wheel ID determination unit 54 arrives at step S12 based on the pulse signal output from the wheel speed sensor 60 (pulse signal output from the magnetic detector 80). The pitch accuracy of the magnetic ring plate 72 is calculated. That is, the pitch accuracy of the magnetic poles of the magnetized ring plate 72 is calculated for each magnetic pole.

  When calculating the wheel speed, the unevenness of the pitch of each magnetic pole is corrected. Similar to the correction calculation, the pitch of each magnetic pole is calculated by calculating a correction coefficient for correcting the pitch error of 48 magnetic poles. The degree of error can be detected. The closer the correction coefficient is to the value “1”, the smaller the pitch error, and the farther the correction coefficient is from the value “1”, the greater the pitch error. In the present embodiment, the correction coefficient is used as an index of pitch accuracy.

The four-wheel ID discriminating unit 54 calculates a correction coefficient for each magnetic pole using the following equation for the four wheels. The correction coefficient calculated by the current calculation is expressed as Coef (n), and the correction coefficient calculated by the previous calculation is expressed as Coef (n-1).
Coef (n) = Coef (n-1) + K (7.5 deg-Coef (n-1) * X) /7.5 deg

  X represents an angle (deg) representing the pulse interval (the width from the rising edge of the pulse signal to the rising edge of the next pulse signal) of the pulse signal output from the wheel speed sensor 60 (encoder). Further, K is a feedback count, and for example, a value of about “0.1” may be adopted. 7.5 deg represents an angle corresponding to a pulse interval for one magnetic pole (360 deg / 48). The initial value of the previous correction coefficient Coef (n−1) is “1”. The previous correction coefficient Coef (n-1) represents the correction coefficient Coef (n) calculated before 48 magnetic poles, that is, before one rotation of the wheel W.

  In step S13, the four-wheel ID discriminating unit 54 determines whether or not the calculation of pitch accuracy (calculation of a correction coefficient serving as an index of pitch accuracy) has been completed for the four wheels. With respect to the four wheels, it is determined that the calculation of the pitch accuracy is completed when there is no difference between the correction coefficient Coef (n) for each magnetic pole and the previous correction coefficient Coef (n-1). The four-wheel ID determination unit 54 returns the processing to step S11 while the calculation of the pitch accuracy is not completed. Thereby, the calculation process of pitch accuracy is repeated.

  When the calculation of the pitch accuracy is completed (S13: Yes), the four-wheel ID discriminating unit 54 stores the magnetic pole position where the pitch error is maximum (the magnetic pole position with the lowest pitch accuracy) for each wheel in the subsequent step S14. To do. More specifically, the pulse signal output from the magnetic detector 80 due to the magnetic action of the magnetic pole with the maximum pitch error is stored using the pulse number. In this embodiment, the pulse number of this pulse signal is number 1. The magnetic pole with the maximum pitch error is located at the connecting portion A of the magnetized ring plate 72. For this reason, the pulse signal of pulse number 1 is always output at a constant wheel rotation position. Therefore, if the pulse signal with the pulse number 1 is detected, the absolute rotational position of the wheel W can be detected by advancing the rotation angle corresponding to the number of pulse signals output from the magnetic detector 80 thereafter. . Hereinafter, the wheel position at which the magnetic pole with the maximum pitch error is detected is referred to as a specific rotational position.

  When the specific rotational position is detected for each wheel speed sensor 60, the four-wheel ID determination unit 54 starts counting pulse signals output from the wheel speed sensors 60 in step S15. That is, the pulse number of the pulse signal when the specific rotational position is detected is set to 1, and the count value of the pulse signal is incremented from “1” every time the pulse signal is input thereafter. When the count value reaches “48”, the count value when the pulse signal is input next is returned to “1”. The timing when the count value returns to “1” is the same as the timing when the rotational position of the wheel W returns to the specific rotational position. Hereinafter, the count value of the pulse signal starting from the specific rotation position may be referred to as a pulse number.

  Subsequently, the four-wheel ID determination unit 54 determines whether or not the vehicle is traveling in step S16. In the present embodiment, as in step S11, it is determined that the vehicle is running when the vehicle speed is equal to or higher than a set speed (for example, 20 km / h). If the vehicle speed condition is satisfied, the four-wheel ID determination unit 54 determines whether or not the sensor ID included in the wireless signal transmitted from the sensor unit 10 has been received in step S17. If not, the process returns to step S16.

  When the four-wheel ID discriminating unit 54 repeats such processing and receives the sensor ID transmitted from the sensor unit 10 while the vehicle is traveling, the four-wheel ID sensor 54 detects the four-wheel wheel speed sensor 60 detected at the time of reception in step S18. The pulse number (count value) of the pulse signal to be output is temporarily stored in the pulse number storage unit 55 in association with the received sensor ID. This pulse number represents the rotational position of the wheel W with respect to the specific rotational position. As described above, the sensor unit 10 transmits a wireless signal when the gravitational acceleration detected by the acceleration sensor 13 is -1G, that is, when the turning position of the sensor unit 10 is the highest point. Therefore, the pulse number at the time of receiving the radio signal is the rotation angle that the wheel W has rotated from the specific rotation position until the sensor unit 10 is positioned at the highest point, that is, the wheel W when the sensor unit 10 is positioned at the highest point. It represents the absolute rotation position.

  FIG. 5 illustrates an example of the relationship between the turning position of the sensor unit 10 and the gravitational acceleration component detected by the acceleration sensor 13, the radio signal transmission timing, and the change in the pulse number of the pulse signal output from the wheel speed sensor 60. FIG. Since the magnetic rotor 70 of the wheel speed sensor 60 is fixed to the hub and the magnetic detector 80 is fixed to the vehicle body side, the specific rotational position and the rotational position when the sensor unit 10 transmits a radio signal (transmission rotational position). The relationship with (and) is always constant. That is, the specific rotation position and the transmission rotation position are maintained at a constant angle difference with respect to the rotation center of the wheel W. Therefore, the pulse number when the wireless signal transmitted from the sensor unit 10 is received is basically constant if the sensor unit 10 and the wheel speed sensor 60 are provided on the common wheel W. In the example of FIG. 5, the pulse number of the wheel speed sensor 60 that detects the rotation of the right front wheel when the sensor unit 10 provided on the right front wheel (FR wheel) transmits a radio signal is always “3”. . Similarly, when the sensor unit 10 provided on the left front wheel (FL wheel) transmits a radio signal, the pulse number of the wheel speed sensor 60 that detects the rotation of the left front wheel is always “8”.

  The wheels W do not rotate at the same speed, but the rotational speeds of the wheels W differ from each other due to an inner wheel difference, an outer wheel difference, a slip, and the like. For this reason, every time a radio signal is received, the pulse numbers of the four wheel speed sensors 60 at the reception timing are sampled. For the reception timing of one sensor ID, except for the wheel speed sensor 60 of one wheel, The pulse number of the three-wheel wheel speed sensor 60 varies. Therefore, it can be estimated that the sensor unit 10 specified by the sensor ID is attached to the wheel W provided with the wheel speed sensor 60 in which the pulse number does not vary. The four-wheel ID discriminating unit 54 discriminates the wheel positions of the four sensor units 10 using this principle.

  When the four-wheel ID discriminating unit 54 stores the pulse number of the pulse signal output from the four-wheel wheel speed sensor 60 in step S18, each of the sensor IDs of the four-wheel sensor unit 10 is recorded five times in step S19. It is determined whether or not the pulse number is stored in the pulse number storage unit 55. That is, it is determined whether or not the reception of the sensor ID and the sampling of the pulse number at the time of reception have been performed five times. If sampling of the pulse number for five times is not completed, the process returns to step S16 and the above-described process is repeated.

  If the vehicle speed falls below the set vehicle speed before sampling of the pulse numbers for five times is completed (S16: No), the four-wheel ID determination unit 54 advances the process to step S11. When the vehicle stops, the magnetic rotor 70 of the wheel speed sensor 60 may vibrate due to an external force, so that the pulse signal of the wheel speed sensor 60 may not be counted properly. Therefore, when the vehicle speed falls below the set vehicle speed, the four-wheel ID determination unit 54 returns the process to step S11, calculates the specific rotational position again, and calculates the pulse number at the specific rotational position as “1”. To "". In this case, the four-wheel ID discriminating unit 54 does not delete the pulse number (sampling value) stored in the pulse number storage unit 55 and maintains the stored state as it is.

  When the four-wheel ID discriminating unit 54 repeats such processing and sampling of the pulse number for five times is completed for each sensor ID (S19: Yes), in step S20, the fluctuation of the pulse number for each sensor ID is minimized. The wheel position of the wheel speed sensor 60 is set as the wheel position at which the sensor unit 10 specified by the sensor ID is provided. FIG. 4 shows a sampling image of pulse numbers stored in the pulse number storage unit 55. The pulse number storage unit 55 stores, for every four sensor IDs, pulse numbers NFR, NFL, NRL, NRR of pulse signals output from the four wheel speed sensors 60 when the sensor IDs are received. . This pulse number becomes a sampling value at the time of reception of five radio signals.

  In this example, with respect to the sensor ID1, the pulse number NFR of the wheel speed sensor 60 provided on the right front wheel is always a constant value “3”. On the other hand, the pulse numbers NFL, NRL, and NRR of the wheel speed sensor 60 provided on the other three wheels fluctuate. Therefore, it can be estimated that the sensor unit 10 specified by the sensor ID 1 is provided on the right front wheel.

  When the four-wheel ID discriminating unit 54 discriminates the wheel position at which the sensor unit 10 is provided for each sensor ID, the four-wheel ID discriminating unit 54 registers the sensor ID in the registration ID storage unit 53 in the subsequent step S21. That is, the sensor ID distinguished for each currently stored wheel position is rewritten to the sensor ID estimated in step S20. Subsequently, the four-wheel ID discriminating unit 54 deletes the pulse number temporarily stored in the pulse number storage unit 55 in step S22 and ends this routine.

According to the wheel information acquisition apparatus of the present embodiment described above, the following effects are obtained.
1. The rotation position of the wheel W is detected based on the number (count value) of pulse signals output after passing through the specific rotation position with reference to the specific rotation position where the rotation position of the wheel W is always constant with respect to the vehicle body. . Therefore, the absolute rotational position of the wheel W can be detected. Thereby, even if the vehicle stops in the middle of the four-wheel ID discrimination routine, the sampling values (pulse numbers NFL, NFR, NRL, NRR) stored before stopping can be used effectively. Therefore, after the start of traveling, only the shortage of sampling values needs to be acquired. For example, if the vehicle stops at the stage where three pulse numbers are sampled, the sampling value of the pulse number for a predetermined number of times (5 times) is obtained by sampling the remaining two pulse numbers after the start of traveling. Is obtained. In this case, it is necessary to perform the specific rotational position detection process (S11 to S14) based on the pitch accuracy again. However, the time required for detecting the specific wheel position is about 20 seconds, compared with the transmission time interval of the radio signal. short. As a result, the time required for determining the wheel position of the sensor unit 10 can be shortened.

2. In the connection portion A of the magnetized ring plate 72, the magnetization orientation is deviated, so that the degree of uniformity of the rotation angle interval θpitch at which the pulse signal is output is lower than in other portions. Therefore, by setting the rotation position of the wheel W detected by the connecting portion A as the specific rotation position, the output state of the pulse signal can be changed at the specific rotation position without newly providing a special member. Moreover, the specific rotation position can be acquired by calculating the position of the magnetic pole where the pitch accuracy is lowered.

3. Each sensor unit 10 transmits a radio signal at a timing at which the turning position around its own axle becomes a preset setting position (the uppermost position in this example). For this reason, the transmission timing of the radio signal can be used as information representing the turning position of the sensor unit 10. Therefore, the rotational position of the wheel W detected by the four-wheel ID discriminating unit 54 when receiving the wireless signal transmitted from the sensor unit 10 is always constant for the wheel W to which the sensor unit 10 is attached. For this reason, it is possible to easily determine the wheel position where the sensor unit 10 is provided.

<Modification>
In the above-described embodiment, a configuration is adopted in which the pulse number is sampled when a radio signal is received, and the wheel position of the sensor unit 10 is determined based on the transition of the pulse number. The configuration that does not need to detect the transition of the is adopted.

  For example, in the case of a four-hole fastening type in which the wheel W is fastened to the hub with four bolts, the wheel W can be fastened to the vehicle body (hub) in four phases (rotational positions). Regardless of the phase at which W is attached to the vehicle body, if the wheel rotation position when the wheel ECU 50 receives a radio signal is not the same between the wheels, the transition of the pulse number may not be detected. The wheel position of the sensor unit 10 can be determined only by the pulse number detected once. For that purpose, the rotational position (pulse number) of the wheel W when the sensor unit 10 transmits a radio signal is not the same among all the wheels, and the angular difference of the rotational position between the wheels is 360 deg. The assembly position of the wheel speed sensor 60 (encoder) may be set so as not to be an integral multiple of the angle divided by the number of fastening bolts (number of fastening holes) of the wheel W.

  The wheel rotation position is calculated by the number of pulse signals after passing through the detection position on the basis of the detection position of the connection part A of the magnetized ring plate 72 (position where the magnetic detector 80 detects the connection part A). . The encoder constituting the wheel speed sensor 60 is assembled to the hub. Therefore, the detection position of the connecting portion A can be arbitrarily determined for each wheel W depending on the assembly position of the encoder.

For example, in the case of a four-hole fastening type wheel W, for the right front wheel, left front wheel, right rear wheel, and left rear wheel, the encoder is mounted on the vehicle body so that the detection position of the connecting portion A is shifted by an angle corresponding to three pulse signals. Assemble. As a result, the pulse number when the radio signal is received can be 12n for the right front wheel, 12n + 3 for the left front wheel, 12n + 6 for the right rear wheel, and 12n + 9 for the right rear wheel. n is four numerical values (0, 1, 2, 3) that change depending on the mounting phase of the wheel W. Accordingly, the pulse number of each wheel has the following values for the four wheel mounting phases.
Right front wheel: 12, 24, 36, 48
Left front wheel: 3, 15, 27, 39
Right rear wheel: 6, 18, 30, 42
Left rear wheel: 9, 21, 33, 45

  According to this, no matter what phase the four wheels W are attached to the hub, the rotational position (pulse number) of the wheels W when the sensor unit 10 transmits a radio signal is the same among all the wheels. Not. Therefore, the wheel ECU 50 can identify the sensor unit 10 that has transmitted the radio signal from the pulse number when the radio signal is received. In the above example, if the pulse number when the radio signal is received is (12n + 6), it can be estimated that the sensor unit 10 that has transmitted the radio signal is the right rear wheel sensor unit 10.

  In this modification, the wheel ECU 50 includes a four-wheel ID determining unit 54 ′ instead of the four-wheel ID determining unit 54. The four-wheel ID discriminating unit 54 'stores a pulse number that should be counted when a wireless signal transmitted from the sensor unit 10 provided at the wheel position is received for each wheel position. For example, in the above example, the pulse number when a radio signal is received should be 12n for the right front wheel, 12n + 3 for the left front wheel, 12n + 6 for the right rear wheel, and 12n + 9 for the right rear wheel. The four-wheel ID discriminating unit 54 ′ stores wheel position discriminating data representing the relationship between the wheel position and the pulse number. Hereinafter, the pulse number specified by the wheel position determination data is referred to as a determination pulse number.

  The four-wheel ID discriminating unit 54 'executes a four-wheel ID discriminating routine shown in FIG. The four-wheel ID discrimination routine of this modification includes processes (steps S11 to S18, S21 to S22) similar to the four-wheel ID discrimination routine (FIG. 3) of the embodiment. Hereinafter, processes similar to those of the embodiment are denoted by the same step numbers as those of the embodiment, and description thereof is omitted.

  When the four-wheel ID discriminating unit 54 ′ receives the sensor ID transmitted from the sensor unit 10 in step S17, in step S18, the four-wheel ID discriminating unit 54 ′ detects the pulse signal output from the four-wheel wheel speed sensor 60 detected at the time of reception. The pulse number (count value) is temporarily stored in the pulse number storage unit 55 in association with the sensor ID. This pulse number represents the rotational position of the wheel W with respect to the specific rotational position.

  In the subsequent step S191, the four-wheel ID determination unit 54 ′ determines whether or not the pulse number of the four-wheel wheel speed sensor 60 is stored in the pulse number storage unit 55 for the sensor ID of the four-wheel sensor unit 10. . In the embodiment, the configuration is such that the pulse numbers for five times are stored, but in this modification, it is only necessary to store the pulse numbers for one time. If the storage of the pulse number for each sensor ID is not completed, the four-wheel ID determination unit 54 'returns the process to step S16.

  Thus, when the storage of the pulse number for each sensor ID is completed (S191: Yes), the four-wheel ID discriminating unit 54 ′ of the four-wheel wheel speed sensor 60 stored in the pulse number storage unit 55 in step S201. The wheel position corresponding to the sensor ID is determined based on the pulse number and the wheel position determination data. The wheel position determination data stores a determination pulse number that should be counted when a wireless signal transmitted from the sensor unit 10 provided at the wheel position is received for each wheel position.

  When the pulse number stored in the pulse number storage unit 55 is compared with the determination pulse number stored in the wheel position determination data, one of the four pulse numbers at the time of receiving each sensor ID is the wheel position. The value is the same as any one of the determination pulse numbers stored in the determination data, and the pulse numbers of the remaining three wheels are not the same as any of the determination pulse numbers stored in the wheel position determination data. Accordingly, the four-wheel ID discriminating unit 54 ′ judges whether or not there is a discriminating pulse number that is the same as the pulse number for each pulse number stored in the pulse number storage unit 55. If there is a discriminating pulse number that is the same, the wheel position set in the discriminating pulse number is used as the wheel position of the sensor unit 10 that transmitted the radio signal that triggered the pulse number. Set.

  For example, the case where the pulse numbers of the four wheels when a radio signal is received from the sensor unit 10 of sensor ID 1 is right front wheel: 13, left front wheel: 15, right rear wheel: 16, left rear wheel: 14 Think. In the wheel position determination data set as described above, 13, 14, and 16 are not stored as determination pulse numbers, and only 15 is stored. For this reason, the left front wheel set as the wheel position of the discrimination pulse number 15 is determined as the wheel position where the sensor unit 10 of the sensor ID1 is provided.

  When the four-wheel ID discriminating unit 54 ′ discriminates the wheel position at which the sensor unit 10 is provided for each sensor ID (S201: Yes), in the subsequent step S21, the sensor ID is associated with the wheel position. Register in the registration ID storage unit 53. Subsequently, in step S22, the pulse number temporarily stored in the pulse number storage unit 55 is deleted, and this routine is terminated.

  According to this modification, the rotation position of the wheel W when the turning position of the sensor unit 10 becomes the set position, that is, the wireless signal transmitted by the sensor unit 10 is received without detecting the transition of the pulse number. The wheel position of the sensor unit 10 can be uniquely determined from the rotational position of the wheel W at the time. Accordingly, it is possible to further reduce the time required to determine the wheel position where the sensor unit 10 is provided. Also, even if the mounting phase of the wheel W to the hub is changed, the pulse numbers output by the wheel speed sensors 60 (encoders) are not the same, so no matter what phase the four wheels W are mounted, The wheel position of the sensor unit 10 can be determined by detecting the pulse number once. In addition, since the hub to which the encoder is assembled has different parts shapes for the front, rear, left and right wheels, it is easy to adjust the encoder assembly for each wheel.

  The wheel information acquisition apparatus of this embodiment has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, the four-wheel ID determination unit 54 of the present embodiment automatically executes a four-wheel ID determination routine every time a preset timing arrives (for example, when the ignition switch is turned on). An operation switch (not shown) may be provided, and the above four-wheel ID determination routine may be started by an operation input of the user operation switch.

  In the present embodiment, the wireless signal is transmitted at a timing when the turning position of the sensor unit 10 becomes a set position (for example, the highest point), but the transmission timing of the wireless signal is not related to the turning position of the sensor unit 10. It may be a thing. For example, the sensor unit 10 may be configured to transmit a radio signal at a predetermined cycle (for example, 1 minute). In this case, the sensor unit 10 may detect the sensor turning position and transmit information including the sensor turning position in a wireless signal. Since the gravity acceleration component of the acceleration G detected by the acceleration sensor 13 changes in a sine wave shape, the sensor turning position can be calculated based on the waveform of the gravity acceleration component (G = sin θ). Therefore, the transmission processing unit 23 of the sensor unit 10 calculates the sensor turning position based on the acceleration G detected by the acceleration sensor 13, and uses the angle information representing the calculated sensor turning position as other information (sensor ID, air pressure P, What is necessary is just to comprise so that it may transmit with a radio signal with tire temperature T). In step S18, the four-wheel ID discriminating unit 54 correlates the pulse number of the pulse signal output from the four-wheel wheel speed sensor 60 detected at the time of reception with the sensor turning position in association with the sensor ID. The number is temporarily stored in the number storage unit 55. In step S20, the wheel position of the wheel speed sensor 60 in which the relationship between the wheel rotation position corresponding to the pulse number and the sensor turning position is constant (the change in the angle difference between the two is minimized) is determined as the sensor ID. What is necessary is just to set as a wheel position in which the sensor unit 10 specified by (2) was provided.

  Further, the four-wheel ID discriminating unit 54 of the present embodiment performs the sampling of the pulse number five times for each sensor ID, but the number of samplings is not limited to five, and may be a plurality of times.

  In the present embodiment, the tire air pressure and the tire temperature are acquired as the wheel state quantities, but a configuration in which only one of them is acquired may be employed. Moreover, you may acquire another wheel state quantity.

  Moreover, in this embodiment, although it is the structure which alert | reports a wheel state (tire pressure information) by a display screen, even if it is the structure which alert | reports a wheel state using the structure which does not use a display screen, for example, an audio | voice announcement apparatus. Good.

  In addition, the sensor unit 10 of the present embodiment can only transmit to the wheel ECU 50, but may be configured to be able to transmit and receive bidirectionally with the wheel ECU 50, for example.

  DESCRIPTION OF SYMBOLS 10 ... Sensor unit, 11 ... Air pressure sensor, 12 ... Temperature sensor, 13 ... Acceleration sensor, 14, 90 ... Antenna, 20 ... Control part, 21 ... Timing setting part, 22 ... ID memory | storage part, 23 ... Transmission process part, 50 ... Wheel ECU, 51 ... Reception processing section, 52 ... Data processing section, 53 ... Registration ID storage section, 54 ... Four-wheel ID discrimination section, 55 ... Pulse number storage section, 60 ... Wheel speed sensor (encoder), 70 ... Magnetic Rotor, 71 ... Washer, 72 ... Magnetized ring plate, 80 ... Magnetic detector, 100 ... Alarm, B ... Vehicle body, W ... Wheel.

Claims (5)

A wheel sensor that is fixed to each wheel of the vehicle, detects a wheel state quantity, and transmits the detected wheel state quantity together with a sensor ID by a radio signal;
A vehicle-side device that is fixed to a vehicle body, receives a radio signal transmitted by the wheel sensor, acquires a wheel state quantity for each registered sensor ID, and performs processing according to the wheel state quantity; In the wheel information acquisition device provided with
Each wheel sensor is configured to transmit a wireless signal including sensor turning position information representing a sensor turning position that is a turning position around its own axle,
The vehicle body side device is:
It is provided on the vehicle body side corresponding to each wheel, and outputs a pulse signal every time the wheel rotates by a predetermined angle, and only when the rotation position of the wheel passes a specific rotation position that is always constant with respect to the vehicle body, Vehicle body side rotation signal output means for changing the output state of the pulse signal;
Vehicle body side rotational position detecting means for detecting the rotational position of each wheel based on the specific rotational position based on the pulse signal output by the vehicle body side rotational signal output means;
A wheel sensor is provided for each wheel sensor based on the relationship between the sensor turning position when the wireless signal transmitted by the wheel sensor is received and the rotational position of each wheel detected by the vehicle body side rotational position detecting means. Sensor wheel position determining means for determining the wheel position received,
A wheel information acquisition device comprising: a sensor wheel position registration unit in which a sensor ID of a wheel sensor from which the wheel position is determined is registered as a sensor ID of the wheel position. The pulse signal output from the vehicle body side rotation signal output means is such that the uniformity of the rotation angle interval at which the pulse signal is output is reduced only when the rotation position of the wheel passes the specific rotation position.
The vehicle body side rotational position detecting means obtains a specific rotational position at which the degree of uniformity of the rotational angle interval at which the pulse signal is output is reduced by calculation, and detects the rotational position of each wheel based on the specific rotational position. The wheel information acquisition device according to claim 1. The vehicle body side rotation signal output means,
A magnetic rotor provided with magnetized ring plates having magnetic poles formed at equal intervals in the circumferential direction so as to be integrally rotatable coaxially with a wheel, and a magnetic rotor provided fixed to a vehicle body to detect magnetism of the magnetized ring plate An encoder having a magnetic detector that outputs the pulse signal with rotation of
In the manufacturing process of the magnetized ring plate, a connecting part that connects both ends of the base material of the magnetized ring plate to each other serves as a portion where the degree of uniformity of the rotation angle interval at which the pulse signal is output decreases. The wheel information acquisition device according to claim 2. Each wheel sensor provides the sensor turning position information to the vehicle body side device by transmitting a wireless signal at a timing when the turning position around its own axle becomes a preset setting position.
The sensor wheel position discriminating means is provided with a wheel sensor for each wheel sensor based on the rotational position of each wheel detected by the vehicle body side rotational position detecting means when the wireless signal transmitted from the wheel sensor is received. 4. The wheel information acquisition device according to claim 3, wherein the determined wheel position is discriminated.   A position where the rotational position detected by the vehicle body side rotational position detecting means when the wireless signal transmitted from the wheel sensor is received is not the same between the wheels, regardless of the phase of the wheel attached to the vehicle body. The wheel information acquisition apparatus according to claim 4, wherein the encoder is assembled to the wheel information acquisition apparatus.

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