JP2014020833A - Wheel position detection device and tire air pressure detection device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more surely receive a transmission frame from a transmitter, and to more surely specify wheel positions.SOLUTION: A delay time from a reference angle is set in accordance with a transmission frequency, and each time the transmission frequency is increased, the delay time is shifted by a fixed period of time. When the angle of a transmitter reaches a reference angle, and the delay time elapses, frame transmission is performed. Thus, it is possible to change a transmission angle at which the frame transmission is performed in accordance with the transmission frequency, and to more surely perform frame reception. On the basis of a lapsed time since the previous frame reception to this time frame reception and the transmission cycle of the frame, it is possible to estimate the transmission frequency since the previous frame reception to this time frame reception. Thus, it is possible to calculate tooth positions in the case of accurately performing the frame transmission at a fixed angle as a reference even when any information on the delay time or the transmission frequency is not included in the frame.

Description

  The present invention relates to a wheel position detection device that automatically detects at which position of a vehicle a target wheel is mounted. In particular, tire pressure is detected by directly attaching a transmitter with a pressure sensor to the wheel to which the tire is attached, transmitting the detection result of the pressure sensor from the transmitter, and receiving it by a receiver attached to the vehicle body. It is suitable to be applied to a direct tire pressure detecting device that performs the above.

  Conventionally, there is a direct type as one of tire pressure detecting devices. In this type of tire pressure detecting device, a transmitter equipped with a sensor such as a pressure sensor is directly attached to a wheel side to which a tire is attached. In addition, an antenna and a receiver are provided on the vehicle body side. When a detection signal from the sensor is transmitted from the transmitter, the detection signal is received by the receiver via the antenna, and tire pressure is detected. Done.

  In such a direct tire pressure detecting device, it is necessary to be able to determine whether the transmitted data is for the host vehicle and to which wheel the transmitter is attached. For this reason, ID information for discriminating whether the vehicle is the own vehicle or another vehicle and discriminating the wheel to which the transmitter is attached is individually given in the data transmitted by the transmitter.

  Further, in order to specify the position of the transmitter from the ID information included in the transmission data, it is necessary to register the ID information of each transmitter in advance on the receiver side in association with the position of each wheel. For this reason, at the time of tire rotation, it is necessary to re-register the transmitter ID information and the wheel positional relationship with the receiver. A technique for automatically performing this registration has been proposed.

  Specifically, it is detected that the wheel has reached a predetermined rotational position based on the acceleration detection signal of the acceleration sensor provided in the transmitter on the wheel side, and the radio signal from the transmitter is also received on the vehicle body side. Detect the rotational position of the wheel. And the wheel position is specified by monitoring the change of these relative angles. In this method, a change in the relative angle between the rotational position of the wheel detected on the wheel side and the rotational position of the wheel detected on the vehicle body side is monitored based on the deviation of a predetermined number of data, and there is a variation with respect to the initial value. The wheel position is specified by determining that the allowable value is exceeded.

  In the above method, a radio signal is transmitted when the wheel reaches a predetermined rotational position. However, there is a place where it is difficult for the radio signal to reach the vehicle body side like so-called Null, and if the rotation position where the radio signal is transmitted is Null, it will not reach the vehicle body side no matter how many times the radio signal is transmitted. There is a problem. In such a case, it may take time to detect the wheel position, or the detection may not be performed.

  Therefore, in Patent Document 1, it is proposed to transmit radio signals at two or more different angles in order to prevent radio signals from being transmitted every time at the null position. .

US Patent Application Publication No. 2012/0112899

  However, even if wireless signals are transmitted at two or more different angles as in Patent Document 1, if one of the points is a null position, the wireless signal transmitted at that point every time. Will not reach the car body. And in patent document 1, although the point to which a radio signal is transmitted is made into two or more, since it is set as the same point every time of wheel position detection, the above-mentioned problem generate | occur | produces even if it performs wheel position detection many times. End up.

  In view of the above points, the present invention provides a wheel position detection device and a tire air pressure detection device including the wheel position detection device that can more reliably receive a transmission frame from a transmitter and can more reliably identify a wheel position. The purpose is to provide.

  In order to achieve the above object, in the invention described in claim 1, the transmitter (2) outputs a detection signal corresponding to an acceleration including a gravitational acceleration component that changes with rotation of a wheel to which the transmitter is attached. The first control unit (23) has an acceleration sensor (22) for outputting, and sets a delay time that is varied by a predetermined time corresponding to the number of transmissions of the frame, and the wheel to which the transmitter is attached is set. The angle of the transmitter is detected on the basis of the gravitational acceleration component included in the detection signal of the acceleration sensor with the central axis as the center and an arbitrary position in the circumferential direction of the wheel as an angle of 0 °. By setting the transmission timing when the delay time has elapsed from the reference angle, frames are repeatedly transmitted at different transmission angles according to the number of transmissions. In the receiver (3), the second control unit (33) stores the frame transmission cycle and the amount of delay time shifted for each transmission, and rotates in conjunction with a plurality of wheels. Gear information indicating the tooth position of the gear is acquired based on the detection signal of the wheel speed sensor (11a to 11d) that outputs a detection signal corresponding to the passage of the tooth of the gear (12a to 12d) to be generated, and the previous frame The number of transmissions from the previous frame reception to the current frame reception is calculated from the reception timing of this time, the current reception timing, and the transmission cycle, and the delay time is estimated based on the number of transmissions and the amount of deviation to determine the frame reception timing. It is characterized in that the wheel to which the transmitter (2) to which the frame is transmitted is attached is specified based on the tooth position and the delay time.

  In this way, the delay time from the reference angle is set according to the number of transmissions, and the delay time is shifted by a certain time each time the number of transmissions increases. Then, frame transmission is performed when the delay time elapses after the transmitter angle reaches the reference angle. As a result, the transmission angle at which frame transmission is performed can be changed according to the number of transmissions, so even if some of them match the position of Null, Null can be avoided in other cases, and transmission can be performed more reliably. Frames can reach the receiver.

  Based on the elapsed time from the previous frame reception to the current frame reception and the frame transmission cycle, the receiver can estimate the number of transmissions from the previous frame reception to the current frame reception. For this reason, the receiver can grasp the delay time without including information on the delay time or the number of transmissions, in other words, angle information. Therefore, it is possible to provide a wheel position detection device that can reliably identify the wheel position without including angle information in the frame while reliably receiving a transmission frame from the transmitter.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a diagram illustrating an overall configuration of a tire air pressure detection device to which a wheel position detection device according to a first embodiment of the present invention is applied. 3 is a diagram illustrating a block configuration of a transmitter 2. FIG. It is a figure which shows the block configuration of TPMS-ECU3. It is the figure which showed the relationship between the angle of the transmitter 2, and the value of a gravity acceleration component. It is the figure which showed the angle of the transmitter 2 in each wheel 5a-5d. It is a timing chart for explaining wheel position detection. It is the image figure which showed the change of gear information. It is the schematic diagram which illustrated the wheel position determination logic. It is the schematic diagram which illustrated the wheel position determination logic. It is the schematic diagram which illustrated the wheel position determination logic. It is the graph which showed the evaluation result of the wheel position. 6 is a chart showing the relationship between the number of transmissions and the delay time. It is the figure which showed an example of the relationship between the angle of the transmitter 2, the frequency | count of transmission, and delay time. It is the figure which showed the relationship between the value of the gravity acceleration component of the detection signal of the acceleration sensor 22, and the transmission timing set by providing a delay time from the reference angle. 6 is a chart showing the relationship between the number of transmissions and the delay time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. First, an overall configuration of a tire air pressure detection device to which a wheel position detection device according to a first embodiment of the present invention is applied will be described with reference to FIG. 1 corresponds to the front of the vehicle 1 and the downward direction of the paper corresponds to the rear of the vehicle 1.

  As shown in FIG. 1, the tire pressure detection device is attached to a vehicle 1 and is a tire pressure detection device ECU (hereinafter referred to as TPMS (Tire Pressure Monitoring System) -ECU) that functions as a transmitter 2 and a receiver. ) 3 and meter 4. The wheel position detection device uses the transmitter 2 and the TPMS-ECU 3 provided in the tire air pressure detection device, and is provided corresponding to each wheel 5 (5a to 5d) from a brake control ECU (hereinafter referred to as a brake ECU) 10. The wheel position is specified by acquiring gear information obtained from detection signals of the obtained wheel speed sensors 11a to 11d.

  As shown in FIG. 1, the transmitter 2 is attached to each of the wheels 5a to 5d, detects the air pressure of the tire attached to the wheels 5a to 5d, and frames information on the tire air pressure indicating the detection result. Store in and send. The TPMS-ECU 3 is attached to the vehicle body 6 side of the vehicle 1 and receives the frame transmitted from the transmitter 2 and performs various processes and calculations based on the reception timing and the detection signal stored in the frame. By doing so, wheel position detection and tire air pressure detection are performed. The transmitter 2 creates a frame by, for example, FSK (frequency shift keying), and the TPMS-ECU 3 reads the data in the frame by demodulating the frame, and performs wheel position detection and tire air pressure detection. Detailed configurations of the transmitter 2 and the TPMS-ECU 3 will be described with reference to FIGS. 2A and 2B.

  As shown in FIG. 2A, the transmitter 2 includes a sensing unit 21, an acceleration sensor 22, a microcomputer 23, a transmission circuit 24, and a transmission antenna 25, and is based on power supply from a battery (not shown). Each part is driven.

  The sensing unit 21 includes, for example, a diaphragm type pressure sensor 21a and a temperature sensor 21b, and outputs a detection signal corresponding to the tire pressure and a detection signal corresponding to the temperature. The acceleration sensor 22 is used to detect the position of the sensor itself at the wheels 5a to 5d to which the transmitter 2 is attached, that is, to detect the position of the transmitter 2 and the vehicle speed. The acceleration sensor 22 according to the present embodiment detects, for example, acceleration according to acceleration in both directions perpendicular to the radial direction of the wheels 5a to 5d, that is, the circumferential direction, among the accelerations acting on the wheels 5a to 5d when the wheels 5a to 5d rotate. Output a signal.

  The microcomputer 23 is a well-known one having a control unit (first control unit) and the like, and executes predetermined processing according to a program stored in a memory in the control unit. Individual ID information including identification information unique to the transmitter for identifying each transmitter 2 and identification information unique to the vehicle for identifying the host vehicle is stored in the memory in the control unit.

  The microcomputer 23 receives the detection signal related to the tire pressure from the sensing unit 21, processes the signal and processes it as necessary, and stores the information related to the tire pressure in the frame together with the ID information of each transmitter 2. . Moreover, the microcomputer 23 monitors the detection signal of the acceleration sensor 22, and detects the position of the transmitter 2 at the wheels 5a to 5d to which the respective transmitters 2 are attached and detects the vehicle speed. When the microcomputer 23 creates a frame, the microcomputer 23 transmits a frame (data transmission) from the transmission antenna 25 to the TPMS-ECU 3 via the transmission circuit 24 based on the position detection result of the transmitter 2 and the vehicle speed detection result. )I do.

  Specifically, the microcomputer 23 starts frame transmission on condition that the vehicle 1 is running, and the angle of the transmitter 2 to which the acceleration sensor 22 is attached is determined based on the detection signal of the acceleration sensor 22. Frame transmission is performed with a timing at which a predetermined delay is further provided as a transmission timing from the timing at which the reference angle is reached. The microcomputer 23 repeats this frame transmission at the timing when the transmission timing is reached.

  The fact that the vehicle is running is determined based on the vehicle speed detection result, and the angle of the transmitter 2 is determined based on the position detection result of the transmitter 2 based on the detection signal of the acceleration sensor 22. . That is, the microcomputer 23 detects the vehicle speed using the detection signal of the acceleration sensor 22, and determines that the vehicle 1 is running when the vehicle speed becomes a predetermined speed (for example, 3 km / h) or more. The output of the acceleration sensor 22 includes acceleration based on centrifugal force (centrifugal acceleration). The vehicle speed can be calculated by integrating the centrifugal acceleration and multiplying the coefficient. For this reason, the microcomputer 23 calculates the centrifugal acceleration by removing the gravitational acceleration component from the output of the acceleration sensor 22, and calculates the vehicle speed based on the centrifugal acceleration.

  Since the acceleration sensor 22 outputs detection signals corresponding to the rotation of the wheels 5a to 5d, the gravitational acceleration component is included in the detection signal during traveling, and the amplitude corresponding to the wheel rotation is increased. Signal. For example, as shown in FIG. 3A, the amplitude of the detection signal is the maximum negative amplitude when the transmitter 2 is located at the upper position around the central axis of the wheels 5a to 5d, and when the transmitter 2 is located at the horizontal position. When it is at zero or a lower position, the maximum amplitude is positive. For this reason, based on this amplitude, the position of the transmitter 2 to which the acceleration sensor 22 is attached can be detected, and the angle of the transmitter 2 can be detected. For example, as shown in FIG. 3B, the angle of the transmitter 2 when the transmitter 2 is positioned at the upper position around the central axis of each of the wheels 5a to 5d can be grasped. As shown in FIG. 3A, the angle of the transmitter 2 is associated with the value of the gravitational acceleration component, so that the angle of the transmitter 2 can be detected based on the value of the gravitational acceleration component.

  Therefore, the reference angle is set when the vehicle speed reaches the predetermined speed or when the angle of the transmitter 2 reaches the predetermined angle after the vehicle speed reaches the predetermined speed. Then, the frame transmission from each transmitter 2 can be performed with the timing at which a predetermined delay is further provided from the timing at which the reference angle is reached as the transmission start timing. After that, frame transmission can be repeatedly performed at the transmission timing. Note that the transmission timing may be every one amplitude period of the value of the gravitational acceleration component. However, in consideration of the battery life, frame transmission is not always performed every period, for example, every predetermined period (for example, 15 seconds). It is preferable to transmit frames at a rate of once per frame.

  The transmission circuit 24 functions as an output unit that transmits the frame transmitted from the microcomputer 23 to the TPMS-ECU 3 through the transmission antenna 25. For frame transmission, for example, radio waves in the RF band are used.

  The transmitter 2 configured in this way is attached to an air injection valve in each of the wheels 5a to 5d, for example, and is arranged so that the sensing unit 21 is exposed inside the tire. Then, the corresponding tire pressure is detected, and as described above, when the vehicle speed exceeds a predetermined speed, the transmitter 2 repeatedly transmits frames through the transmission antenna 25 provided in each transmitter 2 at the transmission timing. . After that, it is possible to transmit the frame at the transmission timing set as described above, but it is better to increase the transmission interval in consideration of the battery life. For this reason, when the time assumed to be necessary for identifying the wheel position elapses, the wheel position determination mode is switched to the periodic transmission mode, and frame transmission is performed at a longer fixed period (for example, every minute), thereby TPMS-ECU 3 side. A signal related to the tire pressure is periodically transmitted to. At this time, for example, by providing a random delay for each transmitter 2, the transmission timing of each transmitter 2 can be shifted, and reception by the TPMS-ECU 3 side due to radio wave interference from a plurality of transmitters 2 is possible. It can be prevented from disappearing.

  Further, as shown in FIG. 2B, the TPMS-ECU 3 includes a receiving antenna 31, a receiving circuit 32, a microcomputer 33, and the like. The TPMS-ECU 3 acquires gear information from the brake ECU 10 through an in-vehicle LAN such as CAN as will be described later, and the teeth indicated by the number of teeth (or the number of teeth) of the gears rotated together with the wheels 5a to 5d. Get the position.

  The receiving antenna 31 is for receiving a frame transmitted from each transmitter 2. The receiving antenna 31 is fixed to the vehicle body 6 and may be an internal antenna disposed in the main body of the TPMS-ECU 3, or may be an external antenna in which wiring is extended from the main body.

  The receiving circuit 32 functions as an input unit that receives a transmission frame from each transmitter 2 received by the receiving antenna 31 and sends the frame to the microcomputer 33. When receiving a signal (frame) through the receiving antenna 31, the receiving circuit 32 transmits the received signal to the microcomputer 33.

  The microcomputer 33 corresponds to a second control unit, and executes wheel position detection processing according to a program stored in a memory in the microcomputer 33. Specifically, the microcomputer 33 performs wheel position detection based on the relationship between the information acquired from the brake ECU 10 and the reception timing at which the transmission frame from each transmitter 2 is received. From the brake ECU 10, the microcomputer 33 acquires the gear information of the wheel speed sensors 11a to 11d provided corresponding to the wheels 5a to 5d at every predetermined period (for example, 10 ms).

  The gear information is information indicating the tooth positions of gears (gears) that are rotated together with the wheels 5a to 5d. The wheel speed sensors 11a to 11d are configured by, for example, electromagnetic pickup sensors that are disposed to face the gear teeth, and change the detection signal as the gear teeth pass. Since these types of wheel speed sensors 11a to 11d output square pulse waves corresponding to the passage of teeth as detection signals, the rising and falling of the square pulse waves pass through the tooth edge of the gear. Will be expressed. Therefore, the brake ECU 10 counts the number of tooth edges of the gear, that is, the number of passing edges from the number of rising and falling edges of the detection signals of the wheel speed sensors 11a to 11d, and the tooth edge at that time at every predetermined cycle. The number is transmitted to the microcomputer 33 as gear information indicating the tooth position. Thereby, in the microcomputer 33, it is possible to grasp which tooth of the gear has passed.

  The number of tooth edges is reset every time the gear rotates once. For example, when the number of teeth provided on the gear is 48 teeth, the number of edges is counted in a total of 96 from 0 to 95, and when the count value reaches 95, it is returned to 0 and counted again.

  Here, the number of tooth edges of the gear is transmitted from the brake ECU 10 to the microcomputer 33 as gear information, but the number of teeth which is a count value of the number of passing teeth may be used. Further, the number of edges or teeth passed during the predetermined period is transmitted to the microcomputer 33, and the microcomputer 33 adds the number of edges or teeth passed during the predetermined period to the previous number of edges or teeth. You may make it count the number of edges or the number of teeth in the period. That is, it is only necessary that the microcomputer 33 can finally acquire the number of edges or the number of teeth in the cycle as gear information. The brake ECU 10 resets the number of gear teeth (or the number of teeth) every time the power is turned off, but again starts measuring at the same time when the power is turned on or when the vehicle speed reaches the predetermined vehicle speed. ing. As described above, even when the power is turned off, the same tooth is represented by the same number of edges (or the number of teeth) while the power is turned off.

  When the microcomputer 33 receives a frame transmitted from each transmitter 2, the microcomputer 33 measures the reception timing, and the number of gear edges at the frame reception timing (or the number of teeth) from the acquired number of gear edges (or the number of teeth) ( Alternatively, the wheel position is detected based on the number of teeth). Thus, the wheel position detection which identifies which wheel 5a-5d each transmitter 2 was attached to is performed based on the reception timing and the tooth position indicated by the gear information. A specific method for detecting the wheel position will be described in detail later.

  Further, the microcomputer 33 stores the ID information of each transmitter 2 and the position of each wheel 5a to 5d to which each transmitter 2 is attached in association with the result of wheel position detection. Then, based on the ID information stored in the transmission frame from each transmitter 2 and the data related to the tire pressure, the tire pressure of each wheel 5a to 5d is detected, and an electrical signal corresponding to the tire pressure is sent to CAN or the like. Is output to the meter 4 through the in-vehicle LAN. For example, the microcomputer 33 detects a decrease in tire air pressure by comparing the tire air pressure with a predetermined threshold Th, and outputs a signal to that effect to the meter 4 when a decrease in tire air pressure is detected. Thus, the meter 4 is informed that the tire pressure of any of the four wheels 5a to 5d has decreased.

  The meter 4 functions as an alarm unit, and as shown in FIG. 1, is arranged at a place where the driver can visually recognize, and is configured by a meter display or the like installed in an instrument panel in the vehicle 1, for example. . For example, when a signal indicating that the tire air pressure has decreased is sent from the microcomputer 33 in the TPMS-ECU 3, the meter 4 displays a decrease in the tire air pressure while identifying the wheels 5a to 5d. Informs that the tire pressure of the specific wheel has decreased.

  Next, the operation of the tire pressure detection device of the present embodiment will be described. Hereinafter, the operation of the tire air pressure detection device will be described, but the description will be divided into wheel position detection and tire air pressure detection performed by the tire air pressure detection device.

  First, wheel position detection will be described. First, as a reference, a wheel position detection method when Null is not taken into account will be described with reference to FIGS. As a case where Null is not taken into account, a case will be described in which the frame position is transmitted when the angle of the transmitter 2 reaches a predetermined transmission angle, and the wheel position is detected by the receiver 3 receiving it.

  On the transmitter 2 side, the microcomputer 23 detects the vehicle speed and the angle of the transmitter 2 of the wheels 5a to 5d by monitoring the detection signal of the acceleration sensor 22 at every predetermined sampling period based on the power supply from the battery. ing. Then, when the vehicle speed reaches a predetermined speed, the microcomputer 23 repeatedly performs frame transmission with a transmission timing when the angle of the transmitter 2 reaches a predetermined transmission angle.

  That is, when the gravitational acceleration component of the detection signal of the acceleration sensor 22 is extracted, a sine wave as shown in FIG. 3A is obtained. Based on this sin wave, the angle of the transmitter 2 is known. For this reason, it detects that the angle of the transmitter 2 became a transmission angle based on the sine wave, and performs frame transmission.

  On the other hand, on the TPMS-ECU 3 side, the gear information of the wheel speed sensors 11a to 11d provided corresponding to the wheels 5a to 5d is acquired from the brake ECU 10 at every predetermined period (for example, 10 ms). Then, the TPMS-ECU 3 measures the reception timing when the frame transmitted from each transmitter 2 is received, and the frame reception timing is determined from the number of edges (or the number of teeth) of the acquired gear. Get the number of gear edges (or the number of teeth).

  At this time, the reception timing of the frame transmitted from each transmitter 2 does not always coincide with the period in which the gear information is acquired from the brake ECU 10. For this reason, the number of gear edges (or the number of teeth) indicated by the gear information acquired in the cycle closest to the frame reception timing from the cycle in which the gear information is acquired from the brake ECU 10 is set to the gear timing at the frame reception timing. It can be used as the number of edges (or the number of teeth). The cycle closest to the reception timing here may be either the cycle immediately before or just after the reception timing. Further, when the frame reception timing is obtained by using the number of gear edges (or the number of teeth) indicated by the gear information acquired in the period immediately before and after the frame reception timing from the period in which the gear information is acquired from the brake ECU 10. The number of edges (or the number of teeth) of the gear may be calculated. For example, the intermediate value of the number of gear edges (or the number of teeth) indicated by the gear information acquired immediately before and after the frame reception timing is used as the number of gear edges (or the number of teeth) at the frame reception timing. Can be used.

  The operation of obtaining the number of gear edges (or the number of teeth) at the reception timing of the frame is repeated every time the frame is received, and the number of gear edges (or the number of gear edges at the received frame reception timing) The wheel position is detected based on the number of teeth. Specifically, the variation in the number of gear edges (or the number of teeth) at the frame reception timing is within a predetermined range set based on the number of gear edges (or the number of teeth) at the previous reception timing. The wheel position is detected by determining whether or not there is.

  For the wheel that has received the frame, the frame is transmitted from the transmitter 2 at the timing when the angle of the transmitter 2 becomes the transmission angle. For this reason, when the transmission angle is the same angle, the tooth position indicated by the number of gear edges (or the number of teeth) at the frame reception timing almost coincides with the previous time. Accordingly, the variation in the number of gear edges (or the number of teeth) at the frame reception timing is small and falls within a predetermined range. This is true even when multiple frames are received, and the variation in the number of gear edges (or the number of teeth) at the reception timing of each frame is within a predetermined range determined at the first frame reception timing. It will fit. On the other hand, for a wheel different from the wheel that received the frame, the tooth position indicated by the number of edges (or the number of teeth) of the gear at the reception timing of the frame transmitted from the transmitter 2 of the other wheel varies.

  That is, since the rotation of the gears of the wheel speed sensors 11a to 11d is linked to the wheels 5a to 5d, the number of edges (or the number of teeth) of the gears at the reception timing of the frames is determined for the wheels that have received the frames. The tooth positions shown are nearly identical. However, the rotation state of the wheels 5a to 5d varies depending on road conditions, turning, lane change, etc., so the rotation states of the wheels 5a to 5d cannot be completely the same. For this reason, for a wheel that is different from the wheel that received the frame, the tooth position indicated by the number of gear edges (or the number of teeth) at the frame reception timing varies.

  Therefore, as shown in FIG. 5, for a wheel different from the wheel that received the frame, from the state in which the number of edges of the gears 12 a to 12 d was 0 when the ignition switch (IG) was turned on, The tooth position at the reception timing gradually varies. The wheel position can be detected by determining whether or not the variation is within a predetermined range.

  For example, as shown in FIG. 6A, it is assumed that the position of the transmitter 2 at the first frame transmission is the first reception angle. Also, the variation allowable width, which is the allowable width for the number of gear edges (or the number of teeth), is a value corresponding to a range of 180 ° centered on the first reception angle (the range of the first reception angle ± 90 °). Suppose there is. Assume that the number of edges is a range of ± 24 edges centered on the number of edges at the first reception, and the number of teeth is a range of ± 12 teeth centered on the number of teeth at the first reception. In this case, as shown in FIG. 6B, if the number of gear edges (or the number of teeth) at the time of the second frame reception is within the range of tolerances determined by the first frame reception, the wheel is The wheel may match the wheel on which the frame was transmitted. In this case, the determination result is TRUE (correct).

  However, also in this case, the variation allowable width is determined around the second reception angle that is the angle of the transmitter 2 at the time of the second frame reception, and is equivalent to 180 ° (± 90 °) around the second reception angle. Value. For this reason, a variation allowable width of 180 ° (± 90 °) centered on the first reception angle that is the previous allowable variation width and a variation allowable width of 180 ° (± 90 °) centered on the second reception angle The overlapping portion becomes a new variation allowable width (edge number range is 12 to 48). A new variation allowable width can be narrowed in the overlapping range.

  Therefore, as shown in FIG. 6C, if the number of gear edges (or the number of teeth) at the time of the third frame reception is outside the range of allowable variation determined by the first and second frame reception, the wheel is It does not match the wheel where the frame was sent. For this reason, the determination result is FALSE (error). At this time, even if it is within the range of allowable variation determined by the first frame reception, if it is outside the range of allowable variation determined by the first and second frame reception, it is determined as FALSE. Yes. In this way, it is possible to specify which of the wheels 5a to 5d the transmitter 2 that has transmitted the received frame is attached to.

  That is, as shown in FIG. 7A, for a frame including ID1 as identification information, the number of gear edges (or the number of teeth) is acquired at each reception timing of the frame, and the corresponding wheel is obtained. This is stored for each (left front wheel FL, right front wheel FR, left rear wheel RL, right rear wheel RR). Each time a frame is received, it is determined whether or not the acquired number of gear edges (or the number of teeth) is within the range of allowable variation, and a transmitter that transmits the frame out of the range is transmitted. 2 is excluded from the attached wheel candidates. And the wheel which was not excluded until the last is registered as a wheel with which the transmitter 2 with which the flame | frame was transmitted was attached. In the case of a frame including ID1, the right front wheel FR, the right rear wheel RR, and the left rear wheel RL are excluded from the candidates in this order, and the remaining left front wheel FL is finally attached to the transmitter 2 to which the frame is transmitted. Register as a wheel.

  Then, as shown in FIGS. 7B to 7D, the same processing as that for a frame including ID1 is performed for a frame including ID2 to ID4 as identification information. Thereby, it is possible to specify the wheel to which the transmitter 2 to which each frame is transmitted is attached, and to specify all four wheels to which the transmitter 2 is attached.

  In this way, it is specified which of the wheels 5a to 5d each frame is attached to. Then, the microcomputer 33 stores the ID information of each transmitter 2 that has transmitted the frame in association with the position of the wheel to which it is attached. Thereby, wheel position detection can be performed.

  However, it is sufficient that all four wheels to which the transmitter 2 is attached can be specified by the method described above, but the location of the transmitter 2 in which the frame transmitted like Null is difficult to reach the TPMS-ECU 3 and the frame transmission is performed. There is a possibility that the transmission angle, which is an angle, matches. In that case, if the transmission angle is always set to the same angle, the frame may not be received by the TPMS-ECU 3 every time.

  Therefore, it is conceivable to change the frame transmission angle for each frame transmission so as to avoid Null. However, even if the frame transmission angle is changed every time the frame is transmitted, the TPMS-ECU 3 cannot receive the signal when the Null position is reached again. Depending on the angle to be changed, for example, when the transmission angle is shifted by 180 ° each time, if the transmission angle and the position of the Null match, there is a possibility that the TPMS-ECU 3 cannot receive the signal once every two times. There is. When the transmission angle at which frame transmission is started every time wheel position detection is performed is set to the same angle, the transmission angle and the null position coincide with each other at a predetermined rate, and the wheel position detection is performed many times. The above-mentioned problem will occur even if it is performed.

  For this reason, in this embodiment, the transmitter 2 counts the number of transmissions, and the transmission timing is set according to the number of transmissions. Specifically, when the transmitter 2 determines that the vehicle is running, the angle of the transmitter 2 is determined by using the angle of the transmitter 2 at the moment when the vehicle speed reaches a predetermined speed or a predetermined angle of the transmitter 2 as a reference angle. Is detected to have become the reference angle. Then, the amount of shift is determined so as to shift the transmission time by a fixed time according to the number of transmissions from the timing at which the reference angle is reached, the delay time is set, and frame transmission is performed with the timing delayed by the delay time as the transmission timing.

  For example, the shift amount can be set so that the delay time increases as the number of transmissions increases, or the shift amount can be set so that the delay time decreases as the number of transmissions increases. In the former case, for example, as shown in FIG. 8, when the number of transmissions is the first time, the delay time is 0 ms, the second time is the delay time of 5 ms, and thereafter the delay time is increased at intervals of 5 ms as the number of transmissions increases. Can be. That is, when the number of transmissions is the Nth, the delay time can be set to (N−1) × 5 ms.

  Thus, by setting the delay time from the reference angle according to the number of transmissions, the angle of the transmitter 2 that performs frame transmission can be changed. For example, assuming that the reference angle is when the angle of the transmitter 2 is 0 ° as shown in FIG. 9, after the reference angle is recognized, the frame transmission is performed with the delay time shown in FIG. 8 according to the number of transmissions. Done. As a result, as shown in FIG. 10, frame transmission can be performed at an angle where the amplitude of the gravitational acceleration component of the detection signal of the acceleration sensor 22 is shifted from the position of the negative maximum amplitude by the delay time. In this way, the transmission angle at which frame transmission is performed can be changed according to the number of transmissions, so even if some of them coincide with the position of Null, Null can be avoided in other cases, and transmission can be performed more reliably. The made frame can be made to reach the TPMS-ECU 3.

  On the other hand, in the TPMS-ECU 3, after detecting the tooth position at the reception timing of the frame, the tooth position is corrected to the tooth position when the reception timing is advanced by the delay time, so that the reference angle is fixed. The tooth position when the frame is transmitted is calculated. For example, the tooth position when the frame is transmitted at the reference angle is calculated by using the reference angle as a reference constant angle. That is, the TPMS-ECU 3 detects the wheel position by confirming whether or not the number of gear edges (or the number of teeth) at the reception timing of the transmitted frame is included in the range of allowable variation. Yes. For this reason, when frame transmission is performed at a plurality of different transmission angles, the number of gear edges (or the number of teeth) at the reception timing of a frame transmitted at different transmission angles is set to that transmitted at the same transmission angle. It will be necessary to correct.

  At this time, if the delay time cannot be grasped in the TPMS-ECU 3, the above correction cannot be performed. However, the TPMS-ECU 3 can recognize the delay time according to the number of transmissions based on the received timing. For this reason, the TPMS-ECU 3 stores in advance the relationship that the delay time is shifted by a fixed time each time the number of transmissions increases (for example, it is increased by 5 ms each time as described above). Correction can be performed.

  As for the number of transmissions, if the number of transmissions from the start of transmission is included in the transmission count data in the frame, it can be easily confirmed on the TPMS-ECU 3 side. The amount of displacement can be corrected. However, as the transmission count data is included, the amount of transmission data increases, leading to a decrease in battery life. For this reason, the number of transmissions from the previous frame reception to the current frame reception is estimated on the TPMS-ECU 3 side using the fact that the frame transmission cycle is determined. Then, the delay time of the frame transmitted this time is estimated from the number of transmissions. The number of transmissions here does not have to be the number of transmissions from the start of transmission, but may be the number of transmissions from the previous frame reception to the current frame reception.

  That is, since it is considered that the frame transmission is performed the number of times corresponding to the elapsed time from the previous frame reception, the number of transmissions from the previous frame reception can be grasped from the elapsed time. Therefore, the elapsed time from the previous frame reception to the current frame reception is calculated as the number of transmission cycles, and the amount of delay time that is shifted by a fixed time with respect to the number of cycles is calculated. By multiplying, the delay time of the frame transmitted this time can be calculated. Therefore, even if the transmission count data is not included in the frame and the number of transmissions from the start of transmission cannot be grasped, the number of transmissions from the previous frame reception to the current frame reception can be grasped, and the above-mentioned problem is not caused. Correction can be performed.

  Actually, the elapsed time from the previous frame reception to the current frame reception also includes the delay time difference, so the transmission from the previous frame reception to the current frame reception is included in consideration of that time. The number of times can be calculated. However, since the transmission cycle is set sufficiently longer than the delay time in consideration of the battery life, the number of transmissions may be calculated ignoring the delay time.

  There may be a case where the frame cannot be received at the null position. However, even in that case, since the delay time can be grasped based on the frame transmission interval and the reception interval of each frame, the above correction can be performed without any problem even if the frame cannot be received at the null position. If the frame at the start of transmission is not received and is received from a frame transmitted thereafter, the frame received for the first time is transmitted at an angle shifted by the delay time from the reference angle. For this reason, when the angle of the frame received thereafter is corrected by the delay time, the angle of the frame received for the first time, that is, the angle shifted from the reference angle is corrected. However, there is no problem because the wheel position is detected only by using the angle as a reference constant angle, and the wheel position cannot be detected unless the angle is corrected to the reference angle.

  Thus, since the number of transmissions can also be grasped by the TPMS-ECU 3, the delay time can be estimated from the number of transmissions when the frame is received by the TPMS-ECU 3. For this reason, it is assumed that the TPMS-ECU 3 grasps the delay time and accurately transmits the frame at the reference angle without including information on the delay time and information on the number of transmissions, in other words, angle information in the frame. The tooth position can be calculated.

  Specifically, the number of gear edges (or the number of teeth) at the reception timing of each frame is corrected by the shift of the transmission angle, and the number of gear edges when the transmission angle is not shifted (or The number of teeth). For example, if the number of gear teeth is 48 and the vehicle speed is 40 km / h and the tire rotation is 200 ms and the delay time is 10 ms, the number of edges corresponding to the delay time is 96 ×. 10 / 200≈5. Similarly, the number of teeth corresponding to the delay time is × 10 / 200≈2. Therefore, the TPMS-ECU 3 corrects the number of edges (or the number of teeth) corresponding to the delay time from the number of edges (or the number of teeth) of the gear at the reception timing, thereby the number of edges (or the number of teeth) at the reference angle. Can be calculated. Then, it is possible to detect the wheel position based on whether or not the corrected number of edges (or the number of teeth) is included in the range of the variation allowable width.

  The TPMS-ECU 3 receives a frame transmitted when the vehicle speed reaches a predetermined speed, and stores gear information at the reception timing. However, the TPMS-ECU 3 has a predetermined travel stop determination speed (for example, 3 km / h) or less. Then, the gear information up to that point is discarded. When the vehicle starts running again, the wheel position is newly detected as described above.

  When wheel position detection is performed in this manner, tire air pressure detection is performed thereafter. Specifically, at the time of tire pressure detection, frames are transmitted from each transmitter 2 at regular intervals, and every time a frame is transmitted from each transmitter 2, four frames of frames are transmitted by the TPMS-ECU 3. Received. Then, the TPMS-ECU 3 specifies which frame 2 is sent from the transmitter 2 attached to the wheels 5a to 5d based on the ID information stored in each frame, and determines each frame from information related to tire pressure. The tire pressure of the wheels 5a to 5d is detected. Thereby, the fall of the tire air pressure of each wheel 5a-5d can be detected, and it becomes possible to specify which tire air pressure of the wheels 5a-5d is falling. When a decrease in tire air pressure is detected, the fact is notified to the meter 4 so that the meter 4 displays the wheel air pressure decrease while identifying the wheels 5a to 5d, and the tire air pressure of the specific wheel is indicated to the driver. Announcing a drop in

  As described above, in this embodiment, the delay time from the reference angle is set according to the number of transmissions, and the delay time is shifted by a certain time each time the number of transmissions increases. Then, frame transmission is performed when the delay time elapses after the angle of the transmitter 2 reaches the reference angle. As a result, the transmission angle at which frame transmission is performed can be changed according to the number of transmissions, so even if some of them match the position of Null, Null can be avoided in other cases, and transmission can be performed more reliably. The frame can reach the TPMS-ECU 3. Based on the elapsed time from the previous frame reception to the current frame reception and the frame transmission cycle, the number of transmissions from the previous frame reception to the current frame reception can also be estimated on the TPMS-ECU 3 side. Therefore, the TPMS-ECU 3 can grasp the delay time without including information on the delay time or the number of transmissions, in other words, angle information, in the frame, and the frame transmission is performed accurately at a fixed reference angle. It is possible to calculate the tooth position in the case of an accident. Therefore, it is possible to provide a wheel position detection device that can reliably identify the wheel position without including angle information in the frame while reliably receiving the transmission frame from the transmitter 2.

  Also, since frame transmission is performed by shifting the transmission angle in accordance with the number of transmissions, even if there is a case where the frame cannot be received at a null position or the like, the frame is surely received on the TPMS-ECU 3 side at other transmission angles. Can be received. For this reason, it is possible to provide a wheel position detection device that can specify the wheel position accurately and more reliably in a shorter time than in the case where repeated frame reception is not possible.

  Further, gear information indicating the tooth positions of the gears 12a to 12d is acquired based on detection signals of the wheel speed sensors 11a to 11d that detect the passage of the teeth of the gears 12a to 12d that are rotated in conjunction with the wheels 5a to 5d. doing. Then, the variation allowable width is set based on the tooth position at the reception timing of the frame, and the wheel position is determined based on whether the tooth position at the subsequent frame reception timing is within the range of the variation allowable width. I have identified. That is, if the tooth position at the reception timing of the frame is outside the range of allowable variation, it is excluded from the wheel candidates attached to the transmitter 2 to which the frame is transmitted, and the remaining wheels are removed from the frame. It is registered as a wheel to which the transmitted transmitter 2 is attached. For this reason, it is possible to specify the wheel position even if a large amount of data is not available.

  Furthermore, a portion that overlaps the variation allowable width based on the tooth position at the frame reception timing and the variation allowable width set at the previous frame reception timing is set as a new variation allowable width. For this reason, a new variation allowable width | variety can be narrowed in these overlapping ranges. Therefore, it is possible to provide a wheel position detection device that can specify the wheel position accurately in a shorter time.

  In addition, the vehicle 1 has started to travel because the vehicle transmission speed is set to the frame transmission condition or the position of the transmitter 2 is detected at each wheel 5a to 5d using the acceleration sensor 22. Although the wheel position can only be detected from the wheel, the wheel position can be detected immediately after traveling. Furthermore, it is possible to detect the wheel position without the need for a trigger machine or the like, as in the case where the wheel position is detected based on the reception intensity of the signal output from the trigger machine.

(Second Embodiment)
A second embodiment of the present invention will be described. In this embodiment, the frame transmission delay time setting method in the wheel position detection function is changed from the first embodiment. Since other aspects are the same as those in the first embodiment, only portions different from those in the first embodiment will be described.

  In the above embodiment, the delay time is increased or decreased as the number of transmissions increases. However, in this embodiment, two delay times corresponding to the number of transmissions are set, and these are alternately set according to the number of transmissions. Apply. For example, as shown in FIG. 11, the delay time is 0 ms when the number of transmissions is an odd number, and the delay time is 5 ms when the number of transmissions is a few corners.

  Thus, by changing the delay time between the odd number and the even number of times of transmission, the delay time from the reference angle can be changed according to the number of times of transmission.

  Note that in either the odd-numbered or even-numbered frame transmission, there is a possibility that frame reception cannot be performed in accordance with the Null position. However, the frame transmission angle is changed according to the delay time from the reference angle, and even if the delay time is the same, if the vehicle speed is different, the rotation angle of the tire that rotates during the delay time will be different. Can hardly be said to continue. Further, whether or not the frame can be received can be easily grasped on the TPMS-ECU 3 side based on the reception interval of each frame since the frame transmission interval is determined at a predetermined period. In other words, since it is considered that the frame transmission is performed the number of times corresponding to the elapsed time from the previous frame reception, it is understood from this elapsed time whether the frame received this time was transmitted to the odd number or the corner number it can. Therefore, even when a frame cannot be received at the Null position, the above correction can be performed without any problem.

(Other embodiments)
In the second embodiment, a case has been described in which two delay times are set for each of the odd number and even number of transmissions. However, the delay time may be greater than two. In that case, different delay times are set in order for each transmission, and when the number of transmissions reaches the number of delay times, different delay times are rotated so that different delay times are set in order again. Set it.

  Moreover, in the said embodiment, it is set as the time when the acceleration sensor 22 is located in the upper position centering on the center axis | shaft of each wheel 5a-5d as an angle which performs flame | frame transmission. However, this is merely an example, and an arbitrary position in the circumferential direction of the wheel may be set to 0 °.

  Further, in the above embodiment, the tooth position such as the number of edges or the number of teeth is corrected by the TPMS-ECU 3 in accordance with the delay time. However, the tolerance for variation may be shifted in accordance with the delay time. For example, a tolerance range used for determination at the time of second frame reception is a range obtained by adding an angle corresponding to the difference between the first and second delay times to a range of 90 ° centered on the first reception angle. To do. As described above, the variation allowable width may be corrected by an angle corresponding to the difference in delay time of each time.

  Further, in the above embodiment, the variation allowable width is changed at each frame reception timing so that the variation allowable width is gradually narrowed. However, the variation allowable width set around the tooth position is constant. . The variation allowable width set around this tooth position can also be changed. For example, the variation in the tooth position may increase as the vehicle speed increases. For this reason, it is possible to set a more accurate variation allowable width by increasing the variation allowable width as the vehicle speed increases. In addition, the longer the sampling period when the acceleration sensor 22 performs acceleration detection, the lower the detection accuracy of the timing when the angle of the transmitter 2 becomes a predetermined angle, so by changing the variation allowable width accordingly, A more accurate variation tolerance can be set. In that case, since the transmitter 2 knows the sampling period and the like, the frame transmitted by the transmitter 2 can be transmitted including data for determining the variation allowable width.

  In the above embodiment, the TPMS-ECU 3 acquires the gear information from the brake ECU 10, but it is sufficient that the TPMS-ECU 3 can acquire the number of tooth edges or the number of teeth of the gear as the gear information. For this reason, it may be acquired from another ECU, or the detection signals of the wheel speed sensors 11a to 11d may be input, and the number of tooth edges or the number of teeth of the gear may be acquired from the detection signals. In particular, in the above-described embodiment, the case where the TPMS-ECU 3 and the brake ECU 10 are configured by separate ECUs has been described. In that case, the ECU directly inputs the detection signals of the wheel speed sensors 11a to 11d, and acquires the number of teeth or the number of teeth of the gear from the detection signals. In that case, since the number of teeth or the number of teeth of the gear can always be obtained, unlike the case where these pieces of information are obtained every predetermined period, based on the gear information exactly at the reception timing of the frame. Wheel position detection can be performed.

  Moreover, although the said embodiment demonstrated the wheel position detection apparatus provided with respect to the vehicle 1 with which the four wheels 5a-5d were provided, this invention is applied similarly also to a vehicle with many wheels. be able to.

  Moreover, in the said embodiment, when performing wheel position specification based on gear information, the variation tolerance width | variety is set based on a tooth position, and wheel position specification is performed based on whether it is out of the range. . Then, by setting a portion where the previous variation allowable width and the current variation allowable width overlap as a new variation allowable width, the variation allowable width is narrowed. As a result, the wheel position can be specified in a shorter period of time, but the TPMS-ECU 3 can be changed by changing the transmission angle based on the delay time corresponding to the number of transmissions without reducing the variation allowable width. Can reliably receive the frame. From this, it is possible to specify the wheel position more accurately and more reliably in a shorter time than in the case where repeated frame reception is not possible.

  Furthermore, although the wheel position specification is performed using the tolerance width of the tooth position, the transmission is performed even when the wheel position specification is performed based on the standard deviation of the tooth position at the time of multiple frame transmissions. By shifting the angle for each frame transmission, the same effect as described above can be obtained.

  In the present invention, it is only necessary that the wheel speed sensors 11a to 11d can detect the passage of gear teeth that are rotated in conjunction with the rotation of the wheels 5a to 5d. For this reason, as a gear, what is necessary is just the structure from which the magnetic resistance differs in which the part located in between the tooth | gear part by which the outer peripheral surface was made into the conductor, and a tooth | gear is repeated. In other words, the outer edge portion is made uneven so that the outer peripheral surface is not only a general structure composed of a convex portion that becomes a conductor and a space that becomes a nonconductor, but, for example, the outer peripheral surface becomes a conductor and a nonconductor A rotor switch composed of an insulator is also included (see, for example, Japanese Patent Laid-Open No. 10-048233).

1 Vehicle 2 Transmitter 3 TPMS-ECU (Receiver)
5 (5a-5d) Wheel 6 Car body 10 Brake ECU
11a to 11d Wheel speed sensor 12a to 12d Gear 21 Sensing unit 22 Acceleration sensor 23, 33 Microcomputer

Claims (5)

Applied to a vehicle (1) to which a plurality of wheels (5a to 5d) equipped with tires are attached to a vehicle body (6);
A transmitter (2) having a first control unit (23) that is provided on each of the plurality of wheels and generates and transmits a frame including unique identification information;
The transmitter, which is provided on the vehicle body side and receives the frame transmitted from the transmitter via the receiving antenna (31), is attached to any of the plurality of wheels. And a second control unit (33) that performs wheel position detection that associates and stores the plurality of wheels and identification information of the transmitter provided on each of the plurality of wheels. (3) a wheel position detecting device comprising:
The transmitter has an acceleration sensor (22) that outputs a detection signal corresponding to an acceleration including a gravitational acceleration component that changes with rotation of a wheel to which the transmitter is attached,
In the transmitter, the first control unit sets a delay time that is varied by a predetermined time corresponding to the number of transmissions of the frame, and is centered on a central axis of a wheel to which the transmitter is attached, and The angle of the transmitter is detected based on the gravitational acceleration component included in the detection signal of the acceleration sensor with an arbitrary position in the circumferential direction of the wheel as an angle of 0 °, and the angle is determined from the predetermined reference angle to the delay. The frame is transmitted repeatedly at different transmission angles according to the number of transmissions by setting the transmission timing as time elapses,
In the receiver, the second control unit stores a transmission period of the frame and a shift amount of the delay time shifted for each transmission, and a gear that is rotated in conjunction with the plurality of wheels. Based on the detection signal of the wheel speed sensor (11a to 11d) that outputs a detection signal corresponding to the passage of the tooth of (12a to 12d), the gear information indicating the tooth position of the gear is acquired, and the previous time of the frame The number of transmissions from the previous frame reception to the current frame reception is calculated from the reception timing, the current reception timing, and the transmission cycle, and the delay time is estimated based on the number of transmissions and the amount of deviation. Based on the tooth position at the reception timing and the delay time, the wheel to which the transmitter to which the frame is transmitted is attached is specified. Wheel position detecting device according to symptoms.   2. The wheel position detection device according to claim 1, wherein the first control unit sets the delay time to be larger as the number of transmissions increases, or to decrease the delay time as the number of transmissions increases.   The first control unit sequentially sets different delay times set with a certain amount of deviation for each transmission, and once the number of transmissions reaches the number of different delay times, the different delay times are set again. The wheel position detection device according to claim 1 or 2, wherein the different delay times are set by rotation so as to be set in order.   The wheel position detection device according to claim 3, wherein the first control unit varies the delay time depending on whether the number of transmissions of the frame is an odd number and an even number. A tire pressure detecting device including the wheel position detecting device according to any one of claims 1 to 4,
The transmitter includes a sensing unit (21) that outputs a detection signal corresponding to an air pressure of the tire provided in each of the plurality of wheels, and the detection signal of the sensing unit is signal-processed by the first control unit. After storing information about tire pressure in a frame, send the frame to the receiver,
The receiver detects the air pressure of the tire provided in each of the plurality of wheels from the information related to the tire air pressure in the second control unit.

Images