tire pressure monitoring system

Abstract

To provide a tire air pressure monitoring system capable of specifying a wheel to which each sensor unit is attached, in a short time while simplifying a system composition.SOLUTION: A tire air pressure monitoring system includes sensor units 2 attached to respective wheels 10a to 10d, an on-vehicle unit 3 provided on the vehicle body 11 side and RFID tags 4 provided on positions corresponding to respective wheels 10a to 10d on the vehicle body 11 side. The sensor units 2 acquire wheel position information from the RFID tags 4 and transmits the acquired wheel position information toward the on-vehicle unit 3. Further, the on-vehicle unit 3, when receiving the wheel position information from the sensor units 2, specifies the positions of the sensor units 2 which transmit the wheel position information based on the wheel position information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to tire pressure monitoring systems. [Background technology]

[0002] One such system is known that can identify which of a plurality of wheels a sensor unit that detects tire air pressure is attached to, even if the tires have been rotated (see, for example, Patent Document 1). Patent Document 1 discloses a technology for identifying the wheel to which each sensor unit is attached based on the relative magnitude of the reception strength of trigger signals transmitted from a trigger device connected to an on-vehicle unit to each sensor unit. The on-vehicle unit and the trigger device are each provided on the vehicle body and connected to each other by a communication line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-158277 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as in Patent Document 1, a communication line connecting the vehicle-mounted unit and the trigger device and a harness for supplying power to the trigger device are required, which inevitably complicates the system configuration.

[0005] In response to this, there is a technology that acquires wheel speed pulses for each wheel from a brake ECU or the like, and identifies the wheel to which each sensor unit is attached based on the correspondence between the wheel speed pulses and the tire rotation angle obtained by each sensor unit.

[0006] However, with this technology, it is not possible to identify the wheels to which each sensor unit is attached unless the vehicle is driven until a clear difference in the rotational angle of each tire is observed.

[0007] An object of the present disclosure is to provide a tire pressure monitoring system that simplifies the system configuration and can quickly identify the wheels to which each sensor unit is attached. [Means for solving the problem]

[0008] Claim 1 、3 The invention described in A tire pressure monitoring system applied to a vehicle (10) having a body (11) and a plurality of wheels (10a to 10f) including tires attached thereto, a sensor unit (2) attached to each of a plurality of wheels and including an air pressure detection unit (21) for detecting the air pressure of the tire; an in-vehicle unit (3) provided on the vehicle body side and including a position identifying section (32) for identifying to which tire of a plurality of wheels the sensor unit is attached; and an electronic tag (4) provided at each of the positions corresponding to the plurality of wheels on the vehicle body side, capable of transmitting wheel position information including a correspondence relationship between the adjacent wheel and the position of the adjacent wheel on the vehicle body to the sensor unit of the nearest adjacent wheel among the plurality of wheels, The sensor unit includes a position information acquisition unit (27) that acquires wheel position information from the electronic tag and a communication unit (24) that transmits the wheel position information to the vehicle-mounted unit; When the position specifying unit receives the wheel position information from the sensor unit, it specifies the position of the sensor unit that transmitted the wheel position information based on the wheel position information. In the invention described in claim 1, when the position of the sensor unit identified by the position identification unit is the mounting position of a double tire having two tires, the vehicle-mounted unit identifies the position of the sensor unit that received wheel position information first as the inner tire, and identifies the position of the sensor unit that received wheel position information thereafter as the outer tire. In the invention described in claim 3, the sensor unit determines whether tire maintenance work, including tire removal and installation, has been performed, and if the result of this determination indicates that tire maintenance work has been performed, it transmits a request signal to the electronic tag requesting the transmission of wheel position information.

[0009] In this way, if the sensor unit is configured to acquire wheel position information from the electronic tag, there is no need to connect the electronic tag to the on-board unit, which simplifies the system configuration compared to conventional technology that connects the trigger device to the on-board unit with a communication line. In addition, unlike conventional technology, there is no need to run the vehicle until there is a clear difference in the rotational angle of each tire, so it is possible to identify the wheels to which each sensor unit is attached in a short time.

[0010] Therefore, according to the tire pressure monitoring system of the present disclosure, it is possible to simplify the system configuration and identify the wheels to which each sensor unit is attached in a short period of time.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall configuration diagram of a tire pressure monitoring system according to a first embodiment. [Figure 2] FIG. 2 is a block diagram of a sensor unit. [Figure 3] FIG. 2 is a block diagram of an in-vehicle unit. [Figure 4] FIG. 1 is a block diagram of an RFID tag. [Figure 5] FIG. 2 is an explanatory diagram for explaining an example of an attachment position of an RFID tag. [Figure 6] FIG. 2 is an explanatory diagram illustrating an example of communication between an RFID tag, a sensor unit, and an in-vehicle unit. [Figure 7] 5 is a flowchart illustrating an example of the flow of a control process in the sensor unit of the first embodiment. [Figure 8] 10 is a flowchart illustrating an example of the flow of a control process in the RFID tag of the first embodiment. [Figure 9]4 is a flowchart illustrating an example of the flow of control processing in the vehicle-mounted unit of the first embodiment. [Figure 10] FIG. 10 is a diagram showing the overall configuration of a tire pressure monitoring system according to a second embodiment. [Figure 11] FIG. 2 is an explanatory diagram for explaining an example of an attachment position of an RFID tag. [Figure 12] FIG. 2 is an explanatory diagram illustrating an example of communication between an RFID tag, a sensor unit, and an in-vehicle unit. [Figure 13] 10 is a flowchart illustrating an example of the flow of a control process executed by an in-vehicle unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the preceding embodiments will be given the same reference numerals, and their description may be omitted. Furthermore, in the embodiments, when only some of the components are described, the components described in the preceding embodiments can be applied to the remaining components. The following embodiments can be partially combined with each other, even if not specifically stated, as long as there is no particular problem with the combination.

[0014] (First embodiment) This embodiment will be described with reference to FIGS. 1 to 9. FIG. 1 is a diagram showing a tire pressure monitoring system (hereinafter referred to as TPMS) having a tire pressure detection function. In this embodiment, an example will be described in which the TPMS of the present disclosure is applied to a four-wheel vehicle 10 having four wheels 10a to 10d. Note that the front, rear, left and right shown in FIG. 1 refer to the front, rear, left and right of the vehicle 10. In the following, when the four wheels 10a to 10d attached to the body 11 of the vehicle 10 are to be distinguished from one another, the four wheels 10a to 10d may be referred to as a left front wheel FL, a right front wheel FR, a left rear wheel RL, and a right rear wheel RR. A single tire having a single tire is mounted on each of the wheels 10a to 10d.

[0015] As shown in Fig. 1, the TPMS includes multiple sensor units 2, an in-vehicle unit 3, and an RFID tag 4. The TPMS monitors tire pressure using each sensor unit 2 and the in-vehicle unit 3, and notifies the user of the monitoring results via a notification unit such as a meter 5. The TPMS also has a wheel position identification function that automatically identifies which of the four wheels 10a to 10d the sensor unit 2 is attached to.

[0016] The sensor unit 2 is a tire sensor that mainly detects tire air pressure. The sensor unit 2 is attached to a plurality of wheels 10a to 10d. The sensor unit 2 detects the air pressure of the tires attached to the wheels 10a to 10d, and transmits information relating to the tire air pressure that indicates the detection results, stored in a frame.

[0017] The vehicle-mounted unit 3 is attached to the body 11 of the vehicle 10, and receives frames transmitted from the sensor unit 2, and detects tire air pressure by performing various processing and calculations based on the information stored therein.

[0018] The RFID tag 4 is an electronic tag that can transmit wheel position information including the correspondence between the adjacent wheel and its position on the vehicle body 11 to the sensor unit 2 of the closest adjacent wheel among the plurality of wheels 10a to 10d.

[0019] As shown in FIG. 2, the sensor unit 2 includes an air pressure detection unit 21, an acceleration sensor 22, a first microcomputer 23, a tire radio 24, a tire-side memory unit 25, a battery 26 that serves as a driving power source for the sensor unit 2, and an RFID reader 27.

[0020] The air pressure detection unit 21 detects the tire air pressure. The air pressure detection unit 21 includes a pressure sensor 211 and a temperature sensor 212, and outputs a detection signal corresponding to the tire air pressure and a detection signal corresponding to the temperature inside the tire.

[0021] The acceleration sensor 22 is a sensor that outputs acceleration that changes with the rotation of the wheels 10a to 10d. The acceleration sensor 22 is used to detect the rotation angle of the sensor unit 2 and the traveling speed (i.e., vehicle speed) of the vehicle 10. The acceleration sensor 22 is configured, for example, as a two-axis acceleration sensor that can detect the radial acceleration and circumferential acceleration of each of the wheels 10a to 10d.

[0022] The first microcomputer 23 is an MCU that constitutes the control unit of the sensor unit 2 and includes a processor, various memories, I / O, etc. MCU is an abbreviation for Micro Controller Unit. The first microcomputer 23 executes predetermined processing in accordance with programs stored in its built-in memory. A unique tire ID for identifying each sensor unit 2 is stored in the memory.

[0023] The first microcomputer 23 receives, for example, detection signals from the pressure sensor 211 and the temperature sensor 212, processes the signals and, if necessary, processes the signals, and stores the tire pressure information together with ID information in a frame. Then, the first microcomputer 23 transmits frames from the tire radio 24 to the in-vehicle unit 3 at a predetermined timing. For example, the first microcomputer 23 transmits frames periodically or irregularly while the vehicle 10 is traveling.

[0024] Here, the ID information is identification information including a unique sensor ID for identifying each sensor unit 2 and a unique in-vehicle device ID for identifying the in-vehicle unit 3 mounted on the subject vehicle. The in-vehicle device ID is subject vehicle identification information for distinguishing the subject vehicle from other vehicles.

[0025] The first microcomputer 23 also monitors the detection signal from the acceleration sensor 22 to determine whether tire maintenance work, including tire removal and installation, such as tire replacement or rotation, has been performed. When tire maintenance work has been performed, the first microcomputer 23 acquires wheel position information and an in-vehicle device ID from the RFID tag 4 and stores this information together with air pressure information in a frame. The first microcomputer 23 then transmits a frame to the in-vehicle unit 3 to identify the positions of the wheels 10a to 10d on which the sensor units 2 are provided.

[0026] The tire radio 24 transmits the wheel position information and ID information acquired from the RFID tag 4 to the in-vehicle unit 3. In this embodiment, the tire radio 24 constitutes a "communication unit." The tire radio 24 includes a first transmitting / receiving circuit 241 and a first communication antenna 242. The first transmitting / receiving circuit 241 is a communication circuit that performs bidirectional communication with the in-vehicle unit 3 via the first communication antenna 242. The first transmitting / receiving circuit 241 performs wireless communication based on a communication method such as BLE. BLE is an abbreviation for Bluetooth (registered trademark) Low Energy. Note that the first transmitting / receiving circuit 241 may perform wireless communication based on a communication method other than BLE.

[0027] The first communication antenna 242 is an antenna for two-way communication with the in-vehicle unit 3. By including the tire radio 24, the sensor unit 2 is not limited to one-way communication from the sensor unit 2 to the in-vehicle unit 3, but is capable of two-way communication with the in-vehicle unit 3. The first communication antenna 242 may be an internal antenna disposed within the body of the sensor unit 2, or may be an external antenna with a wire extended from the body.

[0028] The tire-side memory 25 is configured with a non-volatile memory that can retain information even when the power supply from the battery 26 is stopped. The tire-side memory 25 stores various information such as sensor position information and an on-board device ID received from the on-board unit 3 as registered information. Note that the sensor unit 2 may be configured to store wheel position information and an on-board device ID obtained from the RFID tag 4 as registered information in the tire-side memory 25, instead of the information transmitted from the on-board unit 3.

[0029] The RFID reader 27 is a radio device that transmits coded radio signals to query RFID tags 4 within the signal range of the radio signals and receives response signals and the like from the RFID tags 4. The RFID reader 27 has a main body 271 and an antenna 272. The radio wave output of the RFID reader 27 is set to a magnitude that is limited to communication only with the RFID tags 4 provided around the wheels 10a to 10d to which the sensor units 2 are attached. In other words, the signal range of the RFID reader 27 is limited to the periphery of the wheels 10a to 10d to which the sensor units 2 are attached.

[0030] For example, when tire maintenance work is performed, the RFID reader 27 transmits a request signal to the RFID tag 4 requesting transmission of wheel position information. Then, the RFID reader 27 receives a signal including the wheel position information and the on-board device ID transmitted as a response signal from the RFID tag 4. In this embodiment, the RFID reader 27 constitutes a "position information acquisition unit" that acquires the wheel position information from the RFID tag 4.

[0031] The sensor unit 2 configured in this manner is attached to the air valve AV provided on each of the wheels 10a to 10d. The sensor unit 2 may be configured integrally with the air valve AV or may be configured separately.

[0032] The vehicle-mounted unit 3 is provided in a vehicle body 11. As shown in Fig. 3, the vehicle-mounted unit 3 includes an in-vehicle radio 31, a second microcomputer 32, an in-vehicle storage unit 33, etc. The vehicle-mounted unit 3 is connected to a meter 5, a mobile communication device 6, etc. via an in-vehicle LAN (Local Area Network) such as a CAN (Controller Area Network).

[0033] The in-vehicle radio 31 includes a second communication antenna 311 and a second transmission / reception circuit 312. The second communication antenna 311 is an antenna for performing two-way communication with each sensor unit 2. The second communication antenna 311 is used not only to receive frames and the like sent from each sensor unit 2, but also to transmit signals to each sensor unit 2. The second communication antenna 311 may be an internal antenna disposed within the main body of the in-vehicle unit 3, or may be an external antenna with wiring extending from the main body.

[0034] The second transmission / reception circuit 312 is a communication circuit that communicates bidirectionally with each sensor unit 2 through the second communication antenna 311. The second transmission / reception circuit 312 performs wireless communication based on a communication method such as BLE. The second transmission / reception circuit 312 functions as an input unit that inputs transmission frames received from each sensor unit 2 by the second communication antenna 311 and sends the frames to the second microcomputer 32. When the second transmission / reception circuit 312 receives a frame through the second communication antenna 311, it transmits the received signal to the second microcomputer 32.

[0035] The second microcomputer 32 constitutes a control unit in the on-vehicle unit 3 and is an MCU equipped with a processor, various memories, I / O, etc. The second microcomputer 32 executes a tire pressure detection process in accordance with a program stored in the built-in memory. The second microcomputer 32 also executes a process to identify which tire of the plurality of wheels 10a to 10d the sensor unit 2 is attached to.

[0036] Specifically, the second microcomputer 32 identifies the positions of the wheels 10a to 10d to which the sensor units 2 are attached, based on the wheel position information included in the transmission frame from the sensor units 2. In this embodiment, the configuration in the in-vehicle unit 3 that executes the above-mentioned processing constitutes a "position identification unit."

[0037] The on-board storage unit 33 is configured with a non-volatile memory that can retain information even when the power supply is stopped. The on-board storage unit 33 stores various information received from the sensor unit 2, such as tire pressure information, wheel position information, and ID information.

[0038] The RFID tag 4 is an electronic tag in which wheel position information and an on-board device ID are stored in advance in a memory, and which can transmit a signal including the wheel position information and the on-board device ID to the RFID reader 27. RFID is an abbreviation for Radio Frequency Identification.

[0039] The RFID tag 4 is a passive tag that operates using radio waves emitted by the RFID reader 27 of the sensor unit 2 as its energy source. The RFID tag 4 transmits wheel position information to the sensor unit 2 in response to a request signal from the sensor unit 2 located around the RFID tag 4.

[0040] 4, the RFID tag 4 has an IC chip 41 and an antenna 42. The IC chip 41 has a processor 411 and various memories 412. The IC chip 41 is supplied with power by an induced electromagnetic field generated near the antenna 42.

[0041] An in-vehicle device ID and wheel position information are stored in advance in the memory 412 of the RFID tag 4 as vehicle identification information. The wheel position information is information that includes the correspondence between the nearby wheel that is the closest to the RFID tag 4 among the multiple wheels 10a to 10d and the position of the nearby wheel on the vehicle body 11. For example, the RFID tag 4 arranged around the left front wheel FL on the vehicle body 11 stores in advance, as wheel position information, information indicating that the left front wheel FL is in a left front position on the vehicle body 11.

[0042] Here, the vehicle-mounted device ID may be stored in a non-writable memory (for example, ROM) in the RFID tag 4, or may be stored in a readable and writable memory (for example, RAM or EEPROM).

[0043] The RFID tags 4 are provided at positions corresponding to the plurality of wheels 10a to 10d on the vehicle body 11. In response to a request from the RFID reader 27, the RFID tags 4 transmit wheel position information to the sensor unit 2 of the nearest wheel among the plurality of wheels 10a to 10d.

[0044] The RFID tag 4 is attached to the vehicle body 11. For example, as shown in Fig. 5, the RFID tag 4 is attached to the inner surface of a tire well TH that forms a storage space for the wheels 10a to 10d. The RFID tag 4 is preferably configured in a plate or sheet shape so as not to interfere with other devices. The RFID tag 4 may also be attached directly to a portion of the vehicle body 11 that is close to the wheels 10a to 10d.

[0045] The meter 5 is a display unit provided in the vehicle cabin that displays various information. The meter 5 displays various information when the power is on, specifically when an accessory switch (hereinafter referred to as ACC) or a start switch such as an ignition switch IG is turned on. The display on the meter 5 is basically performed when the power is on.

[0046] The meter 5 is arranged in a location visible to the driver, and is configured, for example, by a multi-information display installed in the instrument panel of the vehicle 10, a display of a navigation device, or the like. For example, when a signal indicating a drop in tire air pressure is sent from the on-vehicle unit 3, the meter 5 notifies the driver of the drop in tire air pressure of the wheel 10a-10d by identifying the wheel 10a-10d and displaying a display indicating the drop in tire air pressure. In this embodiment, the meter 5 constitutes a "notification unit."

[0047] The mobile communication device 6 is a wireless communication unit for communicating with communication destinations outside the vehicle 10. When the ignition switch IG is turned on, the mobile communication device 6 becomes active and wirelessly connects to a wireless base station 61 connected to a communication network 62, thereby communicating with a service center 63 and a cloud server 64 connected to the communication network 62.

[0048] The service center 63 acquires various types of information via the communication network 62 and communicates with a user terminal (not shown) (a terminal carried by the user of the vehicle 10) via the communication network 62. The cloud server 64 is a server created in a cloud environment and stores various types of information. The in-vehicle unit 3 is able to acquire various types of information stored in the cloud server 64 via the communication network.

[0049] The TPMS configured as above monitors the tire pressure of each of the wheels 10a to 10d by performing a tire pressure detection process. The tire pressure detection process is performed periodically or irregularly by the in-vehicle unit 3 of the TPMS.

[0050] In the tire pressure detection process, the tire pressures of the wheels 10a to 10d to which each sensor unit 2 is attached are detected. Specifically, the in-vehicle unit 3 detects the tire pressure of each wheel 10a to 10d based on the ID information and pressure information stored in the transmission frame from each sensor unit 2. Then, an electrical signal corresponding to the tire pressure detection result is output to the meter 5 via an in-vehicle LAN such as a CAN. For example, the in-vehicle unit 3 outputs a message indicating the tire pressure of each wheel 10a to 10d to the meter 5. The in-vehicle unit 3 detects a decrease in tire pressure by comparing the tire pressure detection result with a predetermined alarm threshold, and when a decrease in tire pressure is detected, outputs a message indicating the decrease to the meter 5. This notifies the meter 5 that the tire pressure of one or more of the four wheels 10a to 10d has decreased, and the meter 5 displays this information.

[0051] Here, when tire maintenance work including tire removal and installation is performed, the actual position of the sensor unit 2 may differ from the registered position registered in the in-vehicle unit 3. This is undesirable because it prevents appropriate information from being provided to the user.

[0052] Taking these factors into consideration, when tire maintenance work is performed, the TPMS executes a wheel position identification process to identify which of the multiple wheels 10a to 10d the sensor unit 2 is attached to. An outline of the wheel position identification process will be explained below with reference to FIG.

[0053] 6, in the wheel position identification process, when tire maintenance work is performed, the sensor unit 2 activates the operation of the RFID reader 27 and transmits a request signal requesting wheel position information at a predetermined interval to the RFID tag 4. Upon receiving the request signal, the RFID tag 4 transmits the in-vehicle device ID, wheel position information, etc., possessed by the RFID tag 4 as a response signal to the sensor unit 2 that issued the request signal.

[0054] When the sensor unit 2 receives the response signal from the RFID tag 4, it disables the operation of the RFID reader 27 and stops sending a request signal to the RFID tag 4. Then, the sensor unit 2 stores the wheel position information, the on-board device ID, etc. acquired from the RFID tag 4 in a frame and transmits it to the on-board unit 3 of the vehicle.

[0055] The in-vehicle unit 3 stores the in-vehicle device ID and the like included in the frame received from the sensor unit 2 in the in-vehicle storage unit 33. Furthermore, the in-vehicle unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information based on the wheel position information included in the frame received from the sensor unit 2, and stores the identified position of the sensor unit 2 as sensor position information in the in-vehicle storage unit 33. For example, if the wheel position information indicates that the position of the tire sensor 2 is the left front wheel FL, the in-vehicle unit 3 identifies the position of the sensor unit 2 as the left front wheel FL.

[0056] Then, the on-vehicle unit 3 transmits the sensor position information and on-vehicle device ID stored in the on-vehicle storage unit 33 to the sensor unit 2 that transmitted the frame. When the sensor unit 2 receives the sensor position information and on-vehicle device ID from the on-vehicle unit 3, it stores the sensor position information, on-vehicle device ID, etc. received from the on-vehicle unit 3 as registration information in the tire-side storage unit 25. This allows information to be shared between the sensor unit 2 and the on-vehicle unit 3.

[0057] Next, a control process executed by the sensor unit 2, the RFID tag 4, and the in-vehicle unit 3 as the wheel position identification process will be described. In this embodiment, the control process executed by the sensor unit 2 will first be described with reference to Fig. 7. The process shown in Fig. 7 is executed by the sensor unit 2 periodically or irregularly, for example, when the vehicle 10 is stopped.

[0058] 7, in step S100, the sensor unit 2 determines whether tire maintenance work has been performed on the host vehicle. For example, when the host vehicle is in a stopped state and a predetermined acceleration change is detected by the acceleration sensor 22, the sensor unit 2 determines that tire maintenance work is being performed. The predetermined acceleration change is set to, for example, the fluctuation range of the detection value of the acceleration sensor 22 that occurs when a tire is replaced.

[0059] Here, the stopped state is, for example, a state in which the vehicle speed is less than 5 km / h. Note that in tire maintenance work, in consideration of work efficiency, the doors are often unlocked and the ignition switch IG is on. Therefore, the stopped state may be a state in which the vehicle speed is less than 5 km / h and the doors are unlocked or the ignition switch IG is on. Note that the determination of whether or not the vehicle is in a stopped state can be realized, for example, by acquiring various information from the in-vehicle unit 3.

[0060] If tire servicing work is being performed, the sensor unit 2 determines in step S110 whether or not registration information including location identification information is stored in the tire-side memory unit 25. This determination is made based on the presence or absence of registration information in the tire-side memory unit 25. Note that, for example, if the tire servicing work is a tire change, no registration information is stored in the tire-side memory unit 25 of the sensor unit 2. Also, if the tire servicing work is a tire rotation, the tire-side memory unit 25 of the sensor unit 2 stores registration information that was registered before the tire servicing work was performed.

[0061] Although not shown, when tire servicing work is being performed, the sensor unit 2 transmits a frame including information indicating that tire servicing work has been performed to the in-vehicle unit 3. This allows the in-vehicle unit 3 to also know that tire servicing work has been performed.

[0062] If the tire-side storage unit 25 has registered information, the sensor unit 2 resets the registered information stored in the tire-side storage unit 25 in step S120, and proceeds to processing in step S130. On the other hand, if the tire-side storage unit 25 does not have registered information, the sensor unit 2 skips the processing in step S120 and proceeds to processing in step S130.

[0063] Next, in step S130, the sensor unit 2 enables the operation of the RFID reader 27 and starts the RFID reader 27. As a result, request signals requesting wheel position information are sequentially transmitted from the RFID reader 27 to the RFID tag 4.

[0064] When the RFID reader 27 is activated, the RFID tag 4 starts operating using the radio waves emitted by the RFID reader 27 as an energy source, and the RFID reader 27 executes the control process shown in FIG.

[0065] 8, in step S300, the RFID tag 4 determines whether or not it has received a request signal for wheel position information from the sensor unit 2. The RFID tag 4 waits until it receives the request signal from the sensor unit 2, and proceeds to step S310 when it receives the request signal from the sensor unit 2. In step S310, the RFID tag 4 transmits information including the wheel position information and the in-vehicle device ID as a response signal to the RFID reader 27.

[0066] 7, in step S140, the sensor unit 2 determines whether or not wheel position information has been received from the RFID tag 4. This determination is made based on whether or not a response signal emitted by the RFID tag 4 has been received.

[0067] If wheel position information has been received, in step S150, the sensor unit 2 disables the operation of the RFID reader 27 and stops the RFID reader 27. This stops the transmission of a request signal from the RFID reader 27 to the RFID tag 4.

[0068] Next, in step S160, the sensor unit 2 transmits a frame including the wheel position information and the in-vehicle device ID to the in-vehicle unit 3. Upon receiving the wheel position information from the sensor unit 2, the in-vehicle unit 3 identifies the position of the sensor unit 2 based on the wheel position information and stores the identified position of the sensor unit 2 as position identification information in the in-vehicle storage unit 33. In addition, the in-vehicle unit 3 transmits registration information including the position identification information stored in the in-vehicle storage unit 33 to the sensor unit 2.

[0069] Next, in step S170, the sensor unit 2 determines whether or not registration information has been received from the in-vehicle unit 3. The sensor unit 2 waits until it receives the registration information from the in-vehicle unit 3, and proceeds to step S180 when it receives the registration information from the in-vehicle unit 3. In step S180, the sensor unit 2 stores the registration information in the tire-side memory unit 25 and exits this process.

[0070] On the other hand, if the wheel position information has not been received, the sensor unit 2 determines in step S190 whether a predetermined time has elapsed since the activation of the RFID reader 27. This predetermined time is set, for example, to a time several times the time required from the transmission of the request signal from the RFID reader 27 to the reception of the wheel position information.

[0071] If the predetermined time has not elapsed, the sensor unit 2 returns to step S140, and if the predetermined time has elapsed, the sensor unit 2 proceeds to step S200. In step S200, the sensor unit 2 disables the operation of the RFID reader 27, stops the RFID reader 27, and exits this process. This stops the transmission of a request signal from the RFID reader 27 to the RFID tag 4.

[0072] Here, if the sensor unit 2 has not received wheel position information even after a predetermined time has elapsed since the RFID reader 27 was activated, there is a risk that some kind of malfunction has occurred. Furthermore, if the sensor unit 2 has not received wheel position information, the wheel position identification process cannot be continued. For this reason, the process of step S200 is preferably not only to stop the RFID reader 27 but also to notify the user via a notification unit such as the meter 5 or to transmit to the in-vehicle unit 3 a message indicating that the wheel position identification process cannot be continued.

[0073] This concludes the description of the control processing executed by the sensor unit 2. Below, the control processing executed by the in-vehicle unit 3 as the wheel position identification processing will be described with reference to Fig. 9. Note that the processing shown in Fig. 9 is executed by the in-vehicle unit 3 periodically or irregularly when the vehicle 10 is stopped, for example.

[0074] 9, in step S400, the on-board unit 3 determines whether tire maintenance work has been performed on the vehicle. Specifically, the on-board unit 3 determines whether a frame including a signal indicating that tire maintenance has been performed has been received from the sensor unit 2. Note that the determination in step S400 may be made based on, for example, a detection value of the acceleration sensor 22 included in the frame transmitted from the sensor unit 2.

[0075] The on-board unit 3 waits until tire servicing work is performed, and once the tire servicing work is performed, the process proceeds to step S410. In step S410, the on-board unit 3 resets the sensor position information, etc. of the tire to be serviced. For example, if the sensor position information, etc. of the tire to be serviced is stored in the on-board storage unit 33, the on-board unit 3 deletes the corresponding information from the on-board storage unit 33.

[0076] Next, in step S420, the in-vehicle unit 3 determines whether or not a frame including wheel position information has been received from the sensor unit 2. The in-vehicle unit 3 waits until receiving the wheel position information from the sensor unit 2, and when receiving the wheel position information from the sensor unit 2, the process proceeds to step S430.

[0077] In step S430, the in-vehicle unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information based on the wheel position information, and stores the identified position of the sensor unit 2 in the in-vehicle storage unit 33 as sensor position information.

[0078] Next, in step S440, the in-vehicle unit 3 transmits the sensor position information stored in the in-vehicle storage unit 33 as registration information to the sensor unit 2 that transmitted the wheel position information, and then exits this process. As described above, the frame transmitted by the sensor unit 2 includes a unique tire ID for identifying each sensor unit 2. Therefore, the in-vehicle unit 3 can transmit information to the sensor unit 2 that transmitted the wheel position information.

[0079] The TPMS described above includes a sensor unit 2 attached to each of the wheels 10a to 10d, an in-vehicle unit 3 provided on the vehicle body 11, and an RFID tag 4 provided at a position on the vehicle body 11 corresponding to each of the wheels 10a to 10d. The sensor unit 2 acquires wheel position information from the RFID tag 4 and transmits the acquired wheel position information to the in-vehicle unit 3. Then, upon receiving the wheel position information from the sensor unit 2, the in-vehicle unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information based on the wheel position information.

[0080] This eliminates the need to connect the RFID tag 4 and the in-vehicle unit 3, simplifying the system configuration compared to the prior art in which the trigger device and the in-vehicle unit 3 are connected by a communication line. In addition, unlike the prior art, it is not necessary to run the vehicle 10 until a clear difference in the rotation angle of each tire is observed, so it is possible to identify the wheels 10a-10d to which each sensor unit 2 is attached in a short time. Therefore, the TPMS allows the wheels 10a-10d to which each sensor unit 2 is attached to be identified in a short time while simplifying the system configuration.

[0081] In particular, the TPMS of this embodiment automatically performs the wheel position identification process, eliminating the need for any extra work or operation, and simply performing normal tire maintenance work can identify which of the multiple wheels 10a to 10d the sensor unit 2 is attached to, and register the identified position of the sensor unit 2 as sensor position information.

[0082] In addition, according to the TPMS of this embodiment, the position of the sensor unit 2 can be identified and registered at the time when a tire is mounted on each of the wheels 10a to 10d or when the tire has made one rotation.

[0083] Furthermore, the TPMS of this embodiment has the following advantages.

[0084] (1) The RFID tag 4 is a passive tag that operates using radio waves emitted by the sensor unit 2 as its energy source, and transmits wheel position information to the sensor unit 2 of the nearby wheel in response to a request signal from the sensor unit 2 of the nearby wheel. This eliminates the need for a harness to supply power to the RFID tag 4, thereby simplifying the system configuration.

[0085] (2) The sensor unit 2 determines whether tire maintenance work, including tire removal and installation, has been performed, and if the result of this determination indicates that tire maintenance work has been performed, it transmits a request signal to the RFID tag 4 requesting transmission of wheel position information. This allows the sensor unit 2 to obtain wheel position information through signal exchange between the sensor unit 2 and the RFID tag 4, eliminating the need for communication equipment between the RFID tag 4 and the in-vehicle unit 3 and simplifying the system configuration.

[0086] (3) When the time elapsed since the above determination result indicating the need for tire maintenance exceeds a predetermined time, the sensor unit 2 stops transmitting the request signal. This prevents excessive transmission of request signals from the sensor unit 2 to the RFID tag 4, thereby reducing the power consumption of the sensor unit 2.

[0087] (4) The on-board unit 3 includes an on-board storage unit 33 that stores the positions of the sensor units 2 identified by itself as sensor position information. When the wheels 10a to 10d are removed during tire maintenance work, the on-board unit 3 resets the sensor position information corresponding to the sensor units 2 attached to the removed wheels 10a to 10d. In this way, it is desirable that the on-board unit 3 resets the sensor position information when the wheels 10a to 10d are removed during tire maintenance work. Note that the timing for resetting the sensor position information is not limited to the timing when the wheels 10a to 10d are removed. The timing for resetting the sensor position information may be any timing within the period from when the wheels 10a to 10d are removed until when they are attached.

[0088] (5) The sensor unit 2 includes a tire-side memory unit 25 that stores the sensor position information acquired from the in-vehicle unit 3. When the wheels 10a to 10d are removed for tire maintenance work, the sensor unit 2 resets the sensor position information that was stored in the tire-side memory unit 25 before the wheels were removed. In this way, it is desirable that the sensor unit 2 resets the wheel position information when the wheels 10a to 10d are removed for tire maintenance work.

[0089] (6) The sensor unit 2 includes an acceleration sensor 22 that outputs acceleration that changes with the rotation of the wheels 10a to 10d. When the vehicle 10 is stationary and the acceleration sensor 22 detects a predetermined change in acceleration, the sensor unit 2 determines that tire servicing has been performed. In this way, by using the detection result of the acceleration sensor 22 provided in the sensor unit 2 to determine whether tire servicing has been performed, the system configuration can be simplified compared to when a dedicated sensor device is used to determine whether tire servicing has been performed.

[0090] (7) The RFID tag 4 pre-stores an onboard device ID in addition to wheel position information. This allows not only the location of the sensor unit 2 to be identified but also its registration to be completed in a short time. The onboard device ID may be stored in a non-writable memory (e.g., ROM) in the RFID tag 4, or in a readable / writable memory (e.g., RAM or EEPROM). If the onboard device ID is stored in a non-writable memory, the RFID tag 4 becomes a dedicated product specific to the subject vehicle and cannot be used for other vehicles. On the other hand, if the onboard device ID is stored in a readable / writable memory, for example, the provider or seller of the RFID tag 4 can store or delete the onboard device ID in the memory. Therefore, the RFID tag 4 can be used as a general-purpose product not only for the subject vehicle but also for other vehicles.

[0091] (Second embodiment) Next, a second embodiment will be described with reference to Figures 10 to 13. In this embodiment, differences from the first embodiment will be mainly described.

[0092] 10, in this embodiment, an example will be described in which a TPMS is applied to a six-wheel vehicle 10 having six wheels 10a to 10f. The vehicle 10 has two wheels 10a and 10b attached to the front of a body 11, and four wheels 10c to 10f attached to the rear of the body 11. Hereinafter, when the six wheels 10a to 10f attached to the body 11 of the vehicle 10 are to be distinguished from one another, the six wheels 10a to 10f may be referred to as a left front wheel FL, a right front wheel FR, a left rear front wheel RFL, a right rear front wheel RFR, a left rear rear wheel RRL, and a right rear rear wheel RRR.

[0093] The left front wheel (FL) and the right front wheel (FR) are fitted with single tires, while the left rear front wheel (RFL), right rear front wheel (RFR), left rear rear wheel (RRL), and right rear rear wheel (RRR) are fitted with double tires for increased load-bearing capacity.

[0094] A sensor unit 2 is attached to each tire of each of the wheels 10a to 10f. The left front wheel FL and the right front wheel FR are single tires, so one sensor unit 2 is attached to each. The left rear front wheel RFL, right rear front wheel RFR, left rear rear wheel RRL, and right rear rear wheel RRR are double tires, so two sensor units 2 are attached to each.

[0095] The vehicle-mounted unit 3 is provided in the vehicle body 11. Although FIG. 10 illustrates one vehicle-mounted unit 3 attached to the vehicle body 11, the vehicle-mounted unit 3 is not limited to this. The vehicle-mounted unit 3 may include, for example, multiple relay devices, taking into account the reach of the wireless signal. Furthermore, multiple vehicle-mounted units 3 may be attached to the vehicle body 11.

[0096] The RFID tags 4 are provided on the vehicle body 11 at positions corresponding to the wheels 10a to 10f. Fig. 11 is a schematic perspective view partially illustrating the underside of the vehicle 10. As shown in Fig. 11, the RFID tags 4 are attached, for example, to portions of the vehicle body 11 close to the wheels 10a to 10f. The number of RFID tags 4 is the same as the number of wheels 10a to 10f. The RFID tags 4 may be attached to the wheel wells TH as in the first embodiment.

[0097] Next, the wheel position identification process executed by the TPMS of this embodiment will be described. The wheel position identification process of this embodiment differs from that of the first embodiment in that it is possible to identify whether the sensor unit 2 is attached to the inner tire or the outer tire of a double tire. Note that the wheel position identification process described in the first embodiment is based on the premise that a single tire is attached to each of the wheels 10a to 10d, and does not assume that double tires are attached to some of the wheels 10a to 10f.

[0098] In this case, since the outer tire is attached after the inner tire of a dual tire vehicle, the wheel position information is transmitted to the on-board unit 3 from the sensor unit 2 attached to the inner tire before the sensor unit 2 attached to the outer tire.

[0099] In the wheel position identification process of this embodiment, the order in which the tires are mounted on the dual tire system is taken into consideration, and the position of the sensor unit 2 that receives wheel position information first is identified as the inner tire, and the position of the sensor unit 2 that receives wheel position information next is identified as the outer tire. An outline of the wheel position identification process of this embodiment will now be described with reference to FIG.

[0100] As shown in Figure 12, when tire installation work is performed on the inner tire of a double tire, the sensor unit 2 of the inner tire first enables the operation of the RFID reader 27 and transmits a request signal to the RFID tag 4 at regular intervals, requesting wheel position information.

[0101] When the RFID tag 4 receives the request signal, it transmits the vehicle-mounted device ID, wheel position information, and the like stored in the RFID tag 4 as a response signal to the sensor unit 2 of the inner tire.

[0102] When the sensor unit 2 of the inner tire receives the response signal from the RFID tag 4, it disables the operation of the RFID reader 27 and stops sending request signals to the RFID tag 4. Then, the sensor unit 2 of the inner tire stores the wheel position information and the on-board device ID acquired from the RFID tag 4 together with the air pressure information in a frame and transmits it to the on-board unit 3 of the vehicle.

[0103] The on-vehicle unit 3 stores the air pressure information, on-vehicle device ID, etc. contained in the frame received from the sensor unit 2 of the inner tire in the on-vehicle storage unit 33. Furthermore, based on the wheel position information contained in the frame received from the sensor unit 2 of the inner tire, the on-vehicle unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information as the inner tire. The on-vehicle unit 3 then stores the identified position of the sensor unit 2 as sensor position information in the on-vehicle storage unit 33. For example, if the wheel position information indicates that the position of the tire sensor 2 is the left rear wheel RRL, the on-vehicle unit 3 identifies the position of the sensor unit 2 as the inner tire of the left rear wheel RRL.

[0104] Thereafter, the on-board unit 3 transmits the sensor position information and on-board device ID stored in the on-board memory 33 to the sensor unit 2 of the inner tire that transmitted the frame. Upon receiving the sensor position information and on-board device ID from the on-board unit 3, the sensor unit 2 of the inner tire stores the sensor position information, on-board device ID, etc. received from the on-board unit 3 in the tire-side memory 25 as registration information.

[0105] Next, when the tire mounting work is performed on the outer tire of the double tire, the sensor unit 2 of the outer tire activates the operation of the RFID reader 27 and transmits a request signal to the RFID tag 4 at regular intervals, requesting wheel position information.

[0106] When the RFID tag 4 receives the request signal, it transmits the vehicle-mounted device ID, wheel position information, and the like stored in the RFID tag 4 as a response signal to the sensor unit 2 of the outer tire.

[0107] When the sensor unit 2 of the outer tire receives the response signal from the RFID tag 4, it disables the operation of the RFID reader 27 and stops sending request signals to the RFID tag 4. Then, the sensor unit 2 of the outer tire stores the wheel position information and on-board device ID acquired from the RFID tag 4 together with the air pressure information in a frame and transmits it to the on-board unit 3 of the vehicle.

[0108] The on-board unit 3 stores the air pressure information, on-board device ID, etc. contained in the frame received from the sensor unit 2 of the outer tire in the on-board storage unit 33. Furthermore, based on the wheel position information contained in the frame received from the sensor unit 2 of the outer tire, the on-board unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information as the outer tire. The on-board unit 3 then stores the identified position of the sensor unit 2 as sensor position information in the on-board storage unit 33. For example, if the wheel position information indicates that the position of the tire sensor 2 is the left rear wheel RRL, the on-board unit 3 identifies the position of the sensor unit 2 as the outer tire of the left rear wheel RRL.

[0109] Thereafter, the on-board unit 3 transmits the sensor position information and on-board device ID stored in the on-board memory 33 to the sensor unit 2 of the outer tire that transmitted the frame. Upon receiving the sensor position information and on-board device ID from the on-board unit 3, the sensor unit 2 of the outer tire stores the sensor position information, on-board device ID, etc. received from the on-board unit 3 in the tire-side memory 25 as registration information.

[0110] Hereinafter, the control process executed by the on-vehicle unit 3 as the wheel position identification process will be described with reference to Fig. 13. Note that the process shown in Fig. 13 is executed by the on-vehicle unit 3 periodically or irregularly when the vehicle 10 is stopped, for example.

[0111] 13, the on-board unit 3 determines whether tire maintenance work has been performed on the vehicle in step S400A. This determination process is similar to the process in step S400 in the first embodiment, and therefore a description thereof will be omitted.

[0112] The in-vehicle unit 3 waits until the tire maintenance work is performed, and once the tire maintenance work is performed, the process proceeds to step S410A and resets the sensor position information and the like of the tire to be maintained.

[0113] Next, in step S420A, the in-vehicle unit 3 determines whether or not a frame including wheel position information has been received from the sensor unit 2. The in-vehicle unit 3 waits until receiving the wheel position information from the sensor unit 2, and when receiving the wheel position information from the sensor unit 2, the process proceeds to step S430.

[0114] The vehicle-mounted unit 3 determines whether the sensor unit 2 that transmitted the wheel position information is attached to a single tire. For example, if the wheel 10a to 10d indicated by the wheel position information is one of the left front wheel FL and the right front wheel FR, the vehicle-mounted unit 3 determines that the sensor unit 2 that transmitted the wheel position information is attached to a single tire.

[0115] If the sensor unit 2 that transmitted the wheel position information is a single tire, the in-vehicle unit 3 proceeds to step S440A. In step S440A, the in-vehicle unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information based on the wheel position information, and stores the identified position of the sensor unit 2 in the in-vehicle storage unit 33 as sensor position information.

[0116] Next, in step S450A, the in-vehicle unit 3 transmits the sensor position information stored in the in-vehicle storage unit 33 as registration information to the sensor unit 2 that transmitted the wheel position information, and then exits this process.

[0117] On the other hand, if the sensor unit 2 that transmitted the wheel position information is a dual tire, the in-vehicle unit 3 proceeds to step S460A. In step S460A, the in-vehicle unit 3 determines whether or not the in-vehicle storage unit 33 has registered information related to the inner tire.

[0118] If there is no registration information related to the inner tire in the on-vehicle storage unit 33, the on-vehicle unit 3 proceeds to step S470A. In step S470A, the on-vehicle unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information as the inner tire, and stores the identified position of the sensor unit 2 as sensor position information in the on-vehicle storage unit 33. Thereafter, the on-vehicle unit 3 proceeds to step S450A, transmits the sensor position information stored in the on-vehicle storage unit 33 as registration information to the sensor unit 2 that transmitted the wheel position information, and then exits this process.

[0119] On the other hand, if the on-board storage unit 33 has registration information related to the inner tire, the on-board unit 3 proceeds to step S480A. In step S480A, the on-board unit 3 identifies the position of the sensor unit 2 that transmitted the wheel position information as the outer tire, and stores the identified position of the sensor unit 2 as sensor position information in the on-board storage unit 33. Thereafter, the on-board unit 3 proceeds to step S450A, where it transmits the sensor position information stored in the on-board storage unit 33 as registration information to the sensor unit 2 that transmitted the wheel position information, and then exits this process.

[0120] The rest of the configuration is the same as that of the first embodiment. The TPMS of this embodiment can obtain the same effects as those of the first embodiment that are achieved by a configuration common to or equivalent to that of the first embodiment.

[0121] In addition, the TPMS of this embodiment has the following effects.

[0122] (1) When the position of the sensor unit 2 identified by the in-vehicle unit 3 itself is the mounting position of dual tires, the in-vehicle unit 3 identifies the position of the sensor unit 2 that received wheel position information first as the inner tire, and identifies the position of the sensor unit 2 that received wheel position information thereafter as the outer tire. This makes it possible to accurately identify the position of each sensor unit 2 even in special vehicles equipped with dual tires, such as trucks and trailers.

[0123] (Modification of the second embodiment) In the second embodiment, an example of applying TPMS to a six-wheeled vehicle 10 was described, but the application of TPMS is not limited to this, and it can also be applied to, for example, eight-wheeled or twelve-wheeled vehicles 10.

[0124] (Other embodiments) Representative embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as follows.

[0125] In the above-described embodiment, the configuration of the TPMS and the processing performed by the TPMS have been described in detail, but the TPMS is not limited thereto. The configuration of the TPMS may be partially different from that described in the above-described embodiment. The same applies to the processing performed by the TPMS.

[0126] The TPMS of the above-described embodiment uses the RFID tag 4 as an electronic tag, but an electronic tag other than the RFID tag 4 may also be used. Furthermore, the RFID tag 4 may be an active tag that has its own power source instead of a passive tag.

[0127] As in the above-described embodiment, it is desirable that the TPMS be configured such that when tire maintenance work is performed, the sensor unit 2 transmits a request signal to the RFID tag 4 requesting transmission of wheel position information, but this is not limiting. For example, the TPMS may be configured such that the sensor unit 2 transmits a request signal to the RFID tag 4 based on an instruction from the user.

[0128] As in the above embodiment, the sensor unit 2 is preferably configured to stop transmitting the request signal when a predetermined time has elapsed since the indication that tire maintenance work is to be performed has been received, but is not limited to this. For example, the sensor unit 2 may stop transmitting the request signal after transmitting the request signal a predetermined number of times.

[0129] As in the above embodiment, when the wheels 10a-10d are removed for tire maintenance work, the on-board unit 3 is preferably configured to reset the sensor position information corresponding to the sensor unit 2 of the removed wheels 10a-10d, but is not limited to this. The on-board unit 3 may be configured to reset the sensor position information, for example, when new wheel position information is received from the sensor unit 2.

[0130] As in the above-described embodiment, when the wheels 10a to 10d are removed for tire maintenance work, the sensor unit 2 is preferably configured to reset the sensor position information stored in the tire-side memory 25 before the wheels 10a to 10d are removed, but this is not limiting. The sensor unit 2 may be configured to reset the sensor position information, for example, when new sensor position information is received from the in-vehicle unit 3.

[0131] As in the above embodiment, it is desirable that the sensor unit 2 determines that tire servicing has been performed when a predetermined change in acceleration is detected by the acceleration sensor 22 while the vehicle 10 is stationary, but this is not limiting. The sensor unit 2 may also be configured to determine whether tire servicing has been performed by a method other than the above.

[0132] As in the above embodiment, it is desirable that the RFID tag 4 pre-stores the on-board device ID in addition to the wheel position information, but this is not limitative. The RFID tag 4 may store the wheel position information but not the on-board device ID.

[0133] The sensor unit 2 and the in-vehicle unit 3 in the above-described embodiment are configured to be capable of bidirectional communication based on the BLE communication method, but may also be configured to be capable of bidirectional communication based on a communication method other than BLE.

[0134] In the above-described embodiment, the TPMS of the present disclosure is applied to a vehicle 10 having four or six wheels 10a to 10f, but the TPMS of the present disclosure can also be applied to a vehicle 10 having a different number of wheels.

[0135] In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle.

[0136] In the above-described embodiments, when numerical values such as the number, values, amounts, ranges, etc. of components of the embodiments are mentioned, they are not limited to the specific numbers unless they are expressly stated as being essential or are clearly limited to a specific number in principle.

[0137] In the above-described embodiments, when referring to the shapes, positional relationships, etc. of components, etc., the shapes, positional relationships, etc. are not limited to those unless otherwise specified or when they are limited in principle to specific shapes, positional relationships, etc.

[0138] The controller and method of the present disclosure may be implemented on a special-purpose computer by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. The controller and method of the present disclosure may be implemented on a special-purpose computer by configuring a processor with one or more dedicated hardware logic circuits. The controller and method of the present disclosure may be implemented on one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. The computer program may also be stored on a computer-readable non-transitory tangible storage medium as instructions executed by a computer. [Explanation of symbols]

[0139] 10 vehicles 10a~10f wheels 11 Body 2 Sensor Unit 21 Air pressure detection unit 24 Tire radio (communication unit) 27 RFID reader (location information acquisition unit) 3 In-vehicle unit 32 Second microcomputer (position identification unit) 4. RFID tags (electronic tags)

Claims

1. A tire pressure monitoring system applied to a vehicle (10) having a body (11) and a plurality of wheels (10a to 10f) including tires attached thereto, a sensor unit (2) attached to each of the plurality of wheels and including an air pressure detection unit (21) for detecting the air pressure of the tire; an in-vehicle unit (3) provided on the vehicle body side and including a position identification unit (32) that identifies to which of the plurality of tires of the wheels the sensor unit is attached; an electronic tag (4) provided at each of the positions corresponding to the plurality of wheels on the vehicle body side, capable of transmitting wheel position information including a correspondence relationship between the adjacent wheel and the position of the adjacent wheel on the vehicle body to the sensor unit of the adjacent wheel that is closest among the plurality of wheels; The sensor unit includes a position information acquisition unit (27) that acquires the wheel position information from the electronic tag and a communication unit (24) that transmits the wheel position information to the in-vehicle unit, the position specifying unit, upon receiving the wheel position information from the sensor unit, specifies the position of the sensor unit that transmitted the wheel position information based on the wheel position information; In a tire pressure monitoring system, when the position of the sensor unit identified by the position identification unit is the mounting position of a double tire having two of the tires, the vehicle-mounted unit identifies the position of the sensor unit that received the wheel position information first as the inner tire, and then identifies the position of the sensor unit that received the wheel position information next as the outer tire.

2. 2. The tire pressure monitoring system according to claim 1, wherein the electronic tag is a passive tag that operates using radio waves emitted by the sensor unit as an energy source, and transmits the wheel position information to the sensor unit of the adjacent wheel in response to a request signal from the sensor unit of the adjacent wheel.

3. A tire pressure monitoring system applied to a vehicle (10) having a body (11) and a plurality of wheels (10a to 10f) including tires attached thereto, a sensor unit (2) attached to each of the plurality of wheels and including an air pressure detection unit (21) for detecting the air pressure of the tire; an in-vehicle unit (3) provided on the vehicle body side and including a position identification unit (32) that identifies to which of the plurality of tires of the wheels the sensor unit is attached; an electronic tag (4) provided at each of the positions corresponding to the plurality of wheels on the vehicle body side, capable of transmitting wheel position information including a correspondence relationship between the adjacent wheel and the position of the adjacent wheel on the vehicle body to the sensor unit of the adjacent wheel that is closest among the plurality of wheels; The sensor unit includes a position information acquisition unit (27) that acquires the wheel position information from the electronic tag and a communication unit (24) that transmits the wheel position information to the in-vehicle unit, the position specifying unit, upon receiving the wheel position information from the sensor unit, specifies the position of the sensor unit that transmitted the wheel position information based on the wheel position information; The sensor unit determines whether tire maintenance work, including tire removal and installation, has been performed, and if the result of this determination indicates that tire maintenance work has been performed, transmits a request signal to the electronic tag requesting the transmission of the wheel position information.

4. 4. The tire pressure monitoring system according to claim 3, wherein the sensor unit stops transmitting the request signal when a predetermined time has elapsed since the result of the determination indicated that the tire maintenance work was to be performed.

5. 5. The tire pressure monitoring system according to claim 3, wherein the on-board unit includes an on-board memory unit (33) that stores the position of the sensor unit identified by the position identification unit as sensor position information, and when the wheel is removed during the tire maintenance work, the sensor position information corresponding to the sensor unit attached to the removed wheel is reset.

6. 6. The tire pressure monitoring system of claim 5, wherein the sensor unit includes a tire-side memory unit (25) that stores the sensor position information acquired from the vehicle-mounted unit, and when the wheel is removed for the tire maintenance work, the sensor position information stored in the tire-side memory unit before the wheel was removed is reset.

7. 7. The tire pressure monitoring system according to claim 3, wherein the sensor unit includes an acceleration sensor (22) that outputs an acceleration that changes with the rotation of the wheel, and when the acceleration sensor detects a predetermined change in acceleration while the vehicle is stationary, it determines that the tire maintenance work has been performed.

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