JP2011126371A - Tire air pressure monitoring system and tire air pressure detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire air pressure monitoring system capable of determining at which tire of respective wheels abnormality is caused irrespective of a simple configuration. <P>SOLUTION: The tire air pressure monitoring system includes sensor units SU1-SU4 for detecting the air pressure of the tire and wirelessly transmitting a detection signal including information about the detected air pressure, and monitors the air pressure of the tires of the respective wheels W1-W4 based on the information about the air pressure including in the detection signal. Different magnetic fields are applied to the respective wheels W1-W4 by forming static magnetic fields M1, M2. In the sensor units SU1-SU4, a magnetic field that is applied is detected through a magnetic sensor and information about the magnetic field detected through the magnetic sensor is included in the detection signal and then transmitted. From which one of the sensor units SU1-SU4 of the respective wheels W1-W4 the detection signal is transmitted is determined based on the information about the magnetic field included in the detection signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tire air pressure monitoring system that monitors the air pressure of a tire of each wheel provided in a vehicle, and a tire air pressure detection method that detects the air pressure of the tire of each wheel.

  A so-called tire pressure monitoring system (TPMS: Tire Pressure Monitoring) that monitors the tire air pressure of each wheel provided in the vehicle through a sensor and warns the driver when an abnormality is detected in the tire air pressure. System) is well known. If such a system is installed in the vehicle, the driver can know the abnormality of the tire air pressure at an early stage, so that, for example, the ride comfort and fuel consumption of the vehicle can be kept good and the tread is peeled off. And tire bursts can be prevented.

  By the way, such a tire pressure monitoring system initially warns when an abnormality is detected in any of the air pressures detected through sensors provided on the wheels. That is, a warning is given when an abnormality occurs in any of the tires without specifying a tire in which an abnormality in air pressure has occurred. For this reason, in recent years, a system that allows a driver to discriminate a tire in which an abnormality has occurred is desired in order to quickly and accurately take measures against a tire in which an abnormality in air pressure has occurred. Conventionally, for example, a system described in Patent Document 1 is known as such a system. FIG. 15 shows an outline of a tire pressure monitoring system that has been generally adopted in general, including the system described in Patent Document 1.

  As shown in FIG. 15, in this system, initiators 30a to 30d are provided in the vicinity of the wheels W1 to W4 of the vehicle, respectively, and from the initiators 30a to 30d, the surroundings of the corresponding wheels W1 to W4. Send a trigger signal to. On the other hand, each of the wheels W1 to W4 is provided with sensor units 31a to 31d that detect tire air pressure when a trigger signal is received. When these sensor units 31a to 31d detect tire air pressure, A detection signal including information on the detected air pressure is transmitted. In this system, the detection signals transmitted from the sensor units 31a to 31d are received by the receiver 32 provided in the vehicle, and transmitted to the control device 33 that comprehensively executes various controls related to the system. Is done. The control device 33 monitors the air pressure of each tire based on the air pressure information included in the received detection signal, and when an abnormality is detected in the tire air pressure, an indicator 34 provided in the vehicle interior. To warn the driver through

  On the other hand, in this system, the control device 33 executes transmission control for selectively transmitting a trigger signal from each of the initiators 30a to 30d. Thereby, when the control device 33 receives the detection signal via the receiver 32, the control device 33 determines which of the sensor units 31a to 31d of the wheels W1 to W4 is the detection signal. It becomes possible to grasp. That is, the control device 33 can grasp which wheel tire pressure information is included in the detection signal. Therefore, when the warning is given through the indicator 34, the warning can be given in the form of specifying the tire in which the abnormality in the air pressure has occurred, so that the driver can discriminate the tire in which the abnormality has occurred.

JP 2006-62516 A

  In this way, if an initiator for transmitting a trigger signal is provided in the vicinity of each tire, a warning can be given in the form of identifying a tire in which an abnormality in air pressure has occurred, so that the driver has an abnormality. It is possible to discriminate the tires that have been used. However, in this tire pressure monitoring system, four sets of four initiators and their wiring systems provided corresponding to each tire are required, and this is one factor causing an increase in manufacturing cost.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a tire pressure monitoring system and a tire pressure that can determine which tire of each wheel has an abnormality while having a simple configuration. It is to provide a detection method.

  In order to solve the above-mentioned problem, the invention according to claim 1 is provided with a sensor unit that is provided on each wheel of the vehicle and detects the tire air pressure, and wirelessly transmits a detection signal including information on the detected air pressure. And a tire pressure monitoring system for monitoring the tire pressure of each wheel based on the information on the air pressure included in the detection signal, and a magnet for forming a static magnetic field to apply a different magnetic field to each wheel. The sensor unit includes a magnetic detection element that detects an applied magnetic field, and transmits information including information on a magnetic field detected through the magnetic detection element, the detection unit being configured to detect the detection. Based on the information of the magnetic field included in the signal, while determining which sensor unit of each wheel the same detection signal is transmitted It is summarized as monitoring the tire pressure of the wheels.

  According to a twelfth aspect of the present invention, the sensor unit includes a sensor unit that is provided on each wheel of the vehicle and detects a tire air pressure, and wirelessly transmits a detection signal including information on the detected air pressure. In the tire air pressure detection method for detecting the tire air pressure of each wheel based on the information on the air pressure included in the signal, the wheel includes a magnet for forming a static magnetic field to apply a different magnetic field to each wheel, After detecting the magnetic field applied to the sensor unit, the detected magnetic field information is included in the detection signal and transmitted from the sensor unit, and based on the magnetic field information included in the detection signal, The gist of detecting the tire air pressure of each wheel while discriminating from which sensor unit of each wheel the same detection signal is transmitted. It is.

  According to the system and the method described above, it is possible to determine which tire pressure of each wheel indicates the air pressure information included in the detection signal without requiring the initiator provided on each wheel described above. It becomes possible to discriminate. Therefore, it is possible to determine which tire of each wheel has an abnormality while omitting the initiator and its wiring system from the system and simplifying the configuration.

  In this case, specifically, as in the invention according to claim 2, the magnet has the direction of the magnetic field in each of the right wheel and the left wheel among the wheels as the static magnetic field. The sensor unit includes, as the magnetic field information, information on the direction of the magnetic field detected through the magnetic detection element as the magnetic field information. Based on the information on the direction of the magnetic field included in the detection signal, it is determined whether the detection signal is transmitted from the sensor unit of the right wheel or the left wheel. However, it is effective to employ a configuration in which the tire air pressure of each wheel is monitored. According to such a configuration, it is possible to easily determine whether the information on the air pressure included in the detection signal indicates the air pressure of the right wheel or the left wheel.

  According to a third aspect of the present invention, in the tire pressure monitoring system according to the second aspect, the magnets are configured such that magnetic field directions of the right wheel and the left wheel are different from each other when viewed from the respective wheels. In order to form a static magnetic field, the directions of the magnetic fields on the right wheel and the left wheel are respectively in a first direction from the outside of the vehicle to the inside along their rotation axes, and from the inside to the outside of the vehicle. The gist is that it forms a static magnetic field that is the second direction toward.

  According to the system, even if the sensor unit rotates with the rotation of each wheel, the direction of the magnetic field in each sensor unit is difficult to change. In other words, it is possible to avoid a situation in which the information on the direction of the magnetic field included in the detection signal changes as each wheel rotates. Therefore, since it becomes possible to accurately determine whether the information on the air pressure included in the detection signal indicates the air pressure of the right wheel or the left wheel, the right wheel and the left wheel Which tire has an abnormality can be determined with higher accuracy.

  Moreover, in the tire pressure monitoring system according to any one of claims 1 to 3, as in the invention according to claim 4, the magnet is used as the static magnetic field of the wheels. The sensor unit forms static magnetic fields with different magnetic field strengths at the front and rear wheels, and the sensor unit detects information on the magnetic field strength detected through the magnetic detection element as the magnetic field information. The signal is transmitted by being included in a signal, and the detection signal is transmitted from either the front wheel or the rear wheel based on the information on the magnetic field strength included in the detection signal. It is also effective to adopt a configuration in which the tire pressure of each wheel is monitored while determining whether or not. According to such a configuration, it is possible to easily determine whether the information on the air pressure included in the detection signal indicates the air pressure of the front wheel or the rear wheel.

  According to a fifth aspect of the present invention, in the tire pressure monitoring system according to the fourth aspect, the magnets are different from each other in the direction of the magnetic field in the right wheel and the left wheel of the front wheel when viewed from the respective wheels. The first electromagnet that forms a static magnetic field such that the magnetic field strength at each wheel is greater than or equal to a predetermined value and the direction of the magnetic field at the right and left wheels of the rear wheel are different from each other when viewed from the respective wheels. And a second electromagnet that forms a static magnetic field such that the magnetic field strength at each wheel is equal to or greater than a predetermined value, and selectively energizes the first and second electromagnets. By performing, the magnetic field intensity in any one of the front wheel and the rear wheel is set to be equal to or higher than the predetermined value, and the detection signal is a sensor unit of either the front wheel or the rear wheel. Whether the determination is that the al transmitted, are summarized as be based on the first and energized state to the second electromagnet, and the magnetic field strength information included in the detection signal.

  According to the system, it is only possible to determine whether the information on the air pressure included in the detection signal indicates the air pressure of the front wheel or the rear wheel based on the information on the magnetic field strength included in the detection signal. Instead, it is performed based on the energization state of the first and second electromagnets. For this reason, it becomes possible to perform the above-described determination more accurately, and as a result, it is possible to determine with high accuracy which tire of each wheel has an abnormality.

  Furthermore, in the tire pressure monitoring system according to any one of claims 1 to 3, as in the invention according to claim 6, the sensor unit is not less than a predetermined threshold value through the magnetic detection element. The magnet transmits the detection signal on condition that a magnetic field strength is detected, and the magnet has a magnetic field strength at one of the front wheels and the rear wheels of the wheels equal to or greater than the threshold value. Comprising a third electromagnet that forms a static magnetic field, wherein the magnetic field strength in one of the front wheel and the rear wheel is set to be equal to or greater than the threshold value through energization of the third electromagnet, The determination of whether the detection signal is transmitted from either the front wheel or the rear wheel sensor unit is made such that the magnetic field strength of the front wheel or the rear wheel is greater than or equal to the threshold value. Dolphin performed based on, it is also effective to adopt a configuration such. Even with such a configuration, it is possible to easily determine whether the information on the air pressure included in the detection signal indicates the tire air pressure of the front wheel or the rear wheel.

  The gist of a seventh aspect of the present invention is the tire pressure monitoring system according to any one of the first to fourth aspects, wherein the magnet is an electromagnet that forms the static magnetic field when energized.

According to the system, since the static magnetic field can be changed only by changing the energization amount, the above-described static magnetic field can be easily formed.
According to an eighth aspect of the present invention, in the tire pressure monitoring system according to any one of the fifth to seventh aspects, the electromagnet is provided in a vehicle interior so as to constitute an electronic key system provided in the vehicle. The gist is that the bar antenna is used.

According to the system, since it is not necessary to newly provide an electromagnet, the cost can be further reduced.
A ninth aspect of the present invention provides the tire pressure monitoring system according to any one of the first to eighth aspects, wherein the sensor unit transmits a unique identification registered in advance when transmitting the detection signal. When a code is included in the detection signal and transmitted, and when it is determined from which sensor unit of each wheel the detection signal is transmitted based on the determination result The tire location registration process is performed to store the identification code included in the storage unit in a one-to-one correspondence with the position of each wheel in a one-to-one correspondence. After being stored in the storage means in a corresponding manner, based on the comparison between the identification code included in the detection signal and the identification code stored in the storage means, Information of air pressure contained in the detection signal is summarized in that monitoring the air pressure of said each wheel tire while Determine shows the air pressure of any tire of each wheel.

  According to the system, after the identification code of the sensor unit corresponding to each wheel is determined, the air pressure information included in the detection signal is not generated for any tire on each wheel without forming a static magnetic field. Can be determined. As a result, in a system in which a static magnetic field is formed through energization of the electromagnet, it is not necessary to energize the electromagnet, so that power consumption as the system can be reduced.

  A tenth aspect of the present invention is the tire pressure monitoring system according to any one of the first to ninth aspects, wherein the sensor unit spontaneously transmits the detection signal. Yes.

  According to this system, since it is not necessary to provide an initiator for transmitting a trigger signal for requesting transmission of a detection signal to the sensor unit, it is possible to reduce the number of parts and the cost.

  According to an eleventh aspect of the present invention, in the tire pressure monitoring system according to any one of the first to tenth aspects, the sensor unit is based on information on a magnetic field detected through the magnetic detection element. The gist is that the operation state is switched.

  A conventional sensor unit usually has an antenna built therein, and the sensor unit is started / stopped by receiving the command signal transmitted from the above-described initiator via the antenna, or transmits the detection signal. Is configured to do. In this respect, according to the system described above, the operation state can be switched only by changing the magnetic field applied to the sensor unit, so that it is not necessary to incorporate an antenna as in the conventional initiator. For this reason, the structure of the sensor unit can be simplified.

  According to the tire air pressure monitoring system of the present invention, it is possible to determine which tire of each wheel has an abnormality even with a simple configuration.

The block diagram which shows the system configuration | structure about 1st Embodiment of the tire pressure monitoring system concerning this invention. The block diagram which shows the system configuration | structure of the electronic key system mounted in the vehicle by which the tire pressure monitoring system of the said 1st Embodiment is mounted. The perspective view which shows the perspective structure of the sensor unit about the tire pressure monitoring system of the said 1st Embodiment. The block diagram which shows the system configuration | structure of the sensor unit. The figure which shows typically the content of the detection signal transmitted from the sensor unit. The flowchart which shows the process sequence about the static magnetic field formation process by the tire pressure monitoring system of the said 1st Embodiment. The flowchart which shows the process sequence about the front side tire location registration process by the tire pressure monitoring system of the said 1st Embodiment. The block diagram which shows the operation example of the tire pressure monitoring system of the 1st embodiment. The block diagram which shows the operation example of the tire pressure monitoring system of the 1st embodiment. The block diagram which shows the system configuration | structure about 2nd Embodiment of the tire pressure monitoring system concerning this invention. The flowchart which shows the process sequence about the tire location registration process by the tire pressure monitoring system of the said 2nd Embodiment. The block diagram which shows the system configuration | structure about 3rd Embodiment of the tire pressure monitoring system concerning this invention. The flowchart which shows the process sequence about the rear side tire location registration process by the tire pressure monitoring system of the said 3rd Embodiment. (A), (b) is a timing chart which shows the method of detecting the change pattern of the magnetic field strength by the sensor unit about the modification of the tire pressure monitoring system concerning this invention. The block diagram which shows the system structure about the conventional tire pressure monitoring system.

(First embodiment)
Hereinafter, a first embodiment in which a tire pressure monitoring system according to the present invention is embodied will be described with reference to FIGS. FIG. 1 is a block diagram showing the system configuration of a tire pressure monitoring system. First, the configuration of the tire pressure monitoring system will be described with reference to FIG.

  As shown in FIG. 1, in the tire pressure monitoring system, sensor units SU1 to SU4 are provided on the wheels W1 to W4 of the vehicle, and the tire pressure and temperature are detected through the sensor units SU1 to SU4. Is done. Incidentally, the sensor units SU1 to SU4 generate detection signals including various types of detected tire information, and also wirelessly transmit the generated detection signals. In addition, the vehicle is provided with a receiver 11 that receives the detection signals transmitted from the sensor units SU1 to SU4, and an indicator 12 that displays various types of tire information detected through the sensor units SU1 to SU4. ing. Specifically, as shown in the enlarged view in the drawing, the indicator 12 includes a warning lamp 12a that is turned on when an abnormality occurs in the tire, and a display unit 12b that displays the tire pressure and temperature. Information on the tires W1 to W4 can be displayed individually. The processing of the detection signal received through the receiver 11 and the display processing of the indicator 12 are executed through the system control device 13 mainly composed of a microcomputer.

The vehicle is also equipped with a so-called electronic key system that starts the vehicle-mounted engine through wireless communication with the portable device 20 carried by the driver along with such a tire pressure monitoring system. Next, the configuration and operation of this electronic key system will be briefly described with reference to FIG. As shown in FIG. 2, in this electronic key system, a request signal is transmitted from the front bar antenna 14a disposed between the front wheels W1 and W2 through the transmitter 14 using LF band radio waves. At the same time, a detection signal B is uniformly transmitted through the transmitter 15 from the rear bar antenna 15a disposed between the rear wheels W3 and W4, thereby forming a detection area B in the vehicle interior. On the other hand, when the portable device 20 receives a request signal transmitted to the detection area B, the portable device 20 transmits a response signal including an identification code (ID code). That is, when the user who has the portable device 20 enters the detection area B, a response signal is transmitted from the portable device 20. In this system, the response signal transmitted from the portable device 20 is received by the receiver 11 and transmitted from the receiver 11 to the system control device 13. When the response signal is transmitted in this way, the system control device 13 collates the identification code of the portable device 20 included in the response signal with the identification code stored in the memory 13a as the storage means. Do. The vehicle-mounted engine 17 is started on the condition that it is determined that the identification codes match each other and the engine switch 16 provided in the vicinity of the vehicle steering device is pushed by the user.

  By the way, since the bar antennas 14a and 15a are coil-shaped antennas for transmitting LF band radio waves, they can function as electromagnets by passing a direct current. That is, as indicated by a two-dot chain line in FIG. 1, by forming a direct current through the bar antennas 14a and 15a, the static magnetic fields M1 and M2 that can apply a magnetic field to the wheels W1 to W4 are formed. Is possible. When such static magnetic fields M1 and M2 are formed, the direction of the magnetic field in the right wheels W1 and W3 is as shown by the arrows in the drawing along the rotation axes W1a and W3a from the outside of the vehicle to the inside. The direction of the magnetic field in the left wheels W2 and W4 is the second direction from the inside to the outside of the vehicle along the rotation axes W2a and W4a. That is, the direction of the magnetic field in each of the right wheels W1, W3 and the left wheels W2, W4 is different from each other when viewed from the respective wheels. Therefore, if the sensor units SU1 to SU4 transmit the information on the direction of the magnetic field in the respective detection signals, the detection signals are transmitted from any of the right wheel W1, W3 and the left wheel W2, W4. Can be determined. Incidentally, if the direction of the magnetic field in each wheel W1 to W4 is set in the direction along the rotation axis as described above, even if the sensor units SU1 to SU4 rotate with the rotation of each wheel W1 to W4, The direction of the magnetic field in each sensor unit is difficult to change. In other words, it is possible to avoid a situation in which the information on the direction of the magnetic field included in the detection signal changes as the wheels W1 to W4 rotate.

  Furthermore, since only one of the static magnetic fields M1 and M2 can be formed by selectively energizing the bar antennas 14a and 15a, for example, the front wheels W1 and W2 can be formed by forming only the static magnetic field M1. It is possible to set only the magnetic field intensity at or above the predetermined value B1. That is, the magnetic field strengths at the front wheels W1, W2 and the rear wheels W3, W4 can be made different from each other. Therefore, when the bar antennas 14a and 15a are selectively energized and the sensor units SU1 to SU4 transmit the information on the magnetic field strength in the respective detection signals, the detection signals are transmitted to the front wheels W1 and W2 and the rear wheels. It is possible to determine which sensor unit is transmitted from the wheels W3 and W4.

  Therefore, in the present embodiment, magnetic sensor for detecting the direction and intensity of the magnetic field is provided in each of the sensor units SU1 to SU4, and information on the magnetic field detected through the magnetic sensor is included in the detection signal. To send. And based on the information of the magnetic field contained in this detection signal, it is discriminate | determined from which sensor unit of each wheel W1-W4 the detection signal was transmitted.

  Next, the structure of the sensor units SU1 to SU4 will be described in detail with reference to FIGS. FIG. 3 shows a perspective structure of the sensor units SU1 to SU4, and FIG. 4 shows a system configuration of the sensor units SU1 to SU4 in a block diagram. Since each of the sensor units SU1 to SU4 has the same structure, only the sensor unit SU1 will be described below as a representative for convenience.

  As shown in FIG. 3, the sensor unit SU1 includes a unit main body 21 that incorporates an air pressure sensor, a temperature sensor (not shown), and the like, and a tire valve 22 that protrudes from the unit main body 21 as a portion where air is sucked. And is composed of. Incidentally, the unit body 21 is formed with an air hole 21a for guiding the air sucked from the tire valve 22 to the inside of the tire, and a sensor hole 21b for guiding the air inside the tire to the internal air pressure sensor or temperature sensor. Has been. Further, as shown in FIG. 1, the sensor units SU1 to SU4 are mounted on the wheels W1 to W4 in such a manner that the tire valve 22 faces the outside of the vehicle.

  On the other hand, as shown in FIG. 4, the sensor unit SU1 is provided with various sensors for detecting the state of the tire. Specifically, together with the air pressure sensor 23 and the temperature sensor 24 described above, an acceleration sensor 25 for detecting the acceleration of the tire (strictly speaking, the centrifugal acceleration of the tire), and the remaining amount of the battery that is the power source of the sensor unit SU1. A battery remaining amount sensor 26 to detect and a magnetic sensor 27 to detect a magnetic field applied to the sensor unit SU1 are provided. Here, the magnetic sensor 27 includes a magnetic field strength detector 27a that detects the magnetic field strength in the sensor unit SU1, and a magnetic field direction detector 27b that similarly detects the direction of the magnetic field in the sensor unit SU1. Among these, the former magnetic field strength detection unit 27a is composed of a Hall element that outputs a Hall voltage signal by the Hall effect according to the applied magnetic field strength (magnetic flux density), its signal processing circuit, and the like. A voltage signal corresponding to the magnetic field strength to be output is output. On the other hand, the latter magnetic field direction detector 27b is also composed of a Hall element, its signal processing circuit, and the like, and the direction of the magnetic field in the sensor unit SU1 is the protruding direction of the tire valve 22 (the direction indicated by the arrow a in FIG. 3). It is possible to detect whether it has a component in the same direction as or a component in the direction opposite to the protruding direction of the tire valve 22.

  Then, the output signals of the sensors 23 to 27 are taken into a sensor unit control device 28 that is mainly composed of a microcomputer. The sensor unit control device 28 generates a detection signal based on the output signals of the sensors 23 to 27 and transmits the generated detection signal to the receiver 11 via the transmitter 29. Incidentally, as shown in FIG. 5, the detection signal includes the tire air pressure, the tire temperature, the battery remaining amount, the tire acceleration, and the magnetic field information in the sensor unit SU <b> 1 detected through the sensors 23 to 27. Information such as an identification code unique to the sensor unit SU1 stored in advance in a memory built in the unit controller 28 is included. Here, the magnetic field information is set based on the output signal of the magnetic sensor 27, for example, with a bit string shown in the following (a1) to (a3).

  (A1) A component in which the magnetic field intensity detected through the magnetic field intensity detector 27a is equal to or greater than the predetermined value B1, and the direction of the magnetic field detected through the magnetic field direction detector 27b is opposite to the protruding direction of the tire valve 22. If you have In this case, the magnetic field information is set to the bit string “11”.

  (A2) A component in which the magnetic field intensity detected through the magnetic field intensity detector 27a is equal to or greater than the predetermined value B1, and the direction of the magnetic field detected through the magnetic field direction detector 27b is the same as the protruding direction of the tire valve 22. If you have In this case, the magnetic field information is set to the bit string “00”.

(A3) The magnetic field intensity detected through the magnetic field intensity detection unit 27a is less than the predetermined value B1. In this case, the magnetic field information is set to the bit string “10”.
The sensor unit control device 28 spontaneously transmits a detection signal, and intermittently transmits the detection signal with a predetermined period T. This eliminates the need for providing an initiator for transmitting a trigger signal for requesting transmission of a detection signal to each of the sensor units SU1 to SU4 as in the conventional tire pressure monitoring system described above. Reduction and cost reduction can be achieved.

  And the detection signal transmitted from each sensor unit SU1-SU4 is transmitted to the system control apparatus 13 while receiving via the receiver 11 provided in a vehicle as mentioned above. The system control device 13 determines which of the sensor units SU1 to SU4 of the wheels W1 to W4 has transmitted the detection signal based on the magnetic field information included in the detection signal. And a tire location registration process is performed based on the discrimination | determination result and the various information contained in the detection signal. The tire location registration process stores the identification codes ID1 to ID4 of the sensor units SU1 to SU4 included in the detection signal in the memory 13a in a one-to-one correspondence with the positions of the wheels W1 to W4. In this process, various types of tire information included in the detection signal are displayed on the indicator 12. Further, when executing the tire location registration process, the system controller 13 selectively forms the static magnetic fields M1 and M2 by selectively energizing the bar antennas 14a and 15a. Processing is also executed.

Next, with reference to FIG.6 and FIG.7, the specific procedure of these tire location registration processes and a static magnetic field formation process is demonstrated.
FIG. 6 is a flowchart showing the processing procedure of the static magnetic field forming process executed through the system control device 13. First, the static magnetic field forming process will be described. This process is executed when the in-vehicle engine 17 is started based on the push operation of the engine switch 16.

  As shown in FIG. 6, in this static magnetic field forming process, first, a direct current is passed through the front-side bar antenna 14a to form the static magnetic field M1 (step S10). It is determined whether or not the transmission period T of the detection signal has elapsed since the start of energization of the front bar antenna 14a. Specifically, the elapsed time from the time when the DC current starts to flow through the front bar antenna 14a is measured through the internal timer of the system control device 13, and whether this elapsed time has reached the transmission period T of the detection signal. Judgment is based on whether or not. Here, the formation process of the static magnetic field by the front bar antenna 14a in step S10 is a period in which the transmission period T of the detection signal has not elapsed since the start of energization of the bar antenna 14a (step S11: NO). Only maintained. Then, when the transmission period T of the detection signal has elapsed (step S11: YES), the same energization process is performed on the rear bar antenna 15a.

  That is, a DC current is passed through the rear bar antenna 15a to form the static magnetic field M2 (step S12), and as a process of the subsequent step S13, the detection signal is started from the time when energization to the rear bar antenna 15a is started. It is determined whether or not the transmission cycle T has elapsed. Here, the formation process of the static magnetic field M2 by the rear bar antenna 15a in step S12 is also a period in which the transmission cycle T of the detection signal has not elapsed since the start of energization to the bar antenna 15a (step S13: NO). Only). Then, when the transmission period T of the detection signal has elapsed (step S13: YES), the system control device 13 ends this series of processing.

Next, the tire location registration process will be described.
The tire location registration process mainly includes two processes shown in the following (b1) and (b2).

  (B1) Front-side tire location registration processing that is repeatedly executed with a predetermined calculation period during the period in which the static magnetic field M1 is formed by the front-side bar antenna 14a through the static magnetic field formation processing.

  (B2) A rear tire location registration process that is repeatedly executed with a predetermined calculation period during a period in which the static magnetic field M2 is formed by the rear bar antenna 15a through the static magnetic field forming process.

  The latter rear side tire location registration process is a process according to the former front side tire location registration process, and therefore, only the front side tire location registration process will be described below for convenience of explanation.

FIG. 7 is a flowchart showing a processing procedure of front tire location registration processing executed through the system control device 13.
As shown in FIG. 7, in this front tire location registration process, it is first determined whether or not a detection signal has been received via the receiver 11 (step S20). When the detection signal is received (step S20: YES), it is determined whether or not the static magnetic field information included in the detection signal is the bit string “11” as the processing of the subsequent step S21 (step S21: YES). Step S21). Here, when the static magnetic field information included in the detection signal is the bit string “11” (step S21: YES), it is determined that the detection signal is transmitted from the sensor unit of the right front wheel W1. Then, the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the right front wheel W1 (step S22). Subsequently, various pieces of tire information included in the detection signal are displayed on the indicator 12 as tire information of the right front wheel W1 (step S23), and the system control device 13 ends this series of processing.

  On the other hand, if it is determined in step S21 that the magnetic field information included in the detection signal is not the bit string “11” (step S21: NO), this time, the magnetic field information included in the detection signal is not detected. It is determined whether or not the information is a bit string “00” (step S24). Here, when the magnetic field information included in the detection signal is the bit string “00” (step S24: YES), it is determined that the detection signal is transmitted from the sensor unit of the left front wheel W2. Then, the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the left front wheel W2 (step S25). Further, various pieces of tire information included in the detection signal are displayed on the indicator 12 as tire information of the left front wheel W2 (step S26), and the system control device 13 ends this series of processing.

  When it is determined in the process of step S24 that the magnetic field information included in the detection signal is not the bit string “00” (step S24: NO), that is, the magnetic field information is the bit string “10”. In addition, the system control device 13 ends this series of processing.

  Next, with reference to FIG. 8 and FIG. 9, a description will be given of how the indicator 12 is displayed and the identification codes of the sensor units SU <b> 1 to SU <b> 4 are registered based on the static magnetic field forming process and the tire location registration process. To do.

  As shown in FIG. 8, during the period in which the front-side bar antenna 14a is energized through the static magnetic field forming process, that is, during the period in which the static magnetic field M1 is formed, the magnetic fields in the front wheels W1, W2 Only the intensity is equal to or greater than the predetermined value B1. At this time, since the direction of the magnetic field in the right front wheel W1 is the direction from the outside to the inside of the vehicle, that is, the direction opposite to the protruding direction of the tire valve 22, the detection signal transmitted from the sensor unit SU1 of the right front wheel W1. Becomes a signal including a bit string “11” as magnetic field information. Therefore, when this detection signal is received via the receiver 11, the identification code ID1 included in the detection signal is stored in the memory 13a as the identification code of the sensor unit SU1 of the right front wheel W1, and similarly Various pieces of tire information included in the detection signal are displayed on the indicator 12 as tire information of the right front wheel W1. On the other hand, the direction of the magnetic field in the left front wheel W2 is the same as the direction from the inner side to the outer side of the vehicle, that is, the protruding direction of the tire valve 22, so the detection signal transmitted from the sensor unit SU2 of the left front wheel W2 The signal includes a bit string “00” as the information. Therefore, when this detection signal is received via the receiver 11, the identification code ID2 included in the detection signal is stored in the memory 13a as the identification code of the sensor unit SU2 of the left front wheel W2, and similarly Various types of tire information included in the detection signal are displayed on the indicator 12 as tire information of the left front wheel W2. Since the magnetic field strength at the rear wheels W3 and W4 is equal to or less than the predetermined value B1, the detection signal transmitted from the sensor units SU3 and SU4 is a signal including the bit string “10” as magnetic field information. Based on this, the registration process of the identification code and the display process of the indicator 12 are not performed.

  Subsequently, as shown in FIG. 9, during the period in which the rear-side bar antenna 15a is energized through the static magnetic field forming process, that is, the period in which the static magnetic field M2 is formed, this time, the rear wheel W3. , W4, the same processing is performed, the identification codes ID3, ID4 of the sensor units SU3, SU4 are stored in the memory 13a, and the tire information of the rear wheels W3, W4 is displayed on the indicator 12.

  According to such a configuration as a tire pressure monitoring system, tire information of each wheel W1 to W4 can be displayed on the indicator 12 while omitting the initiator and the wiring system provided in the conventional system. It becomes like this. For this reason, it becomes possible to determine through the indicator 12 which tire of each of the wheels W1 to W4 has an abnormality.

  Incidentally, the system control device 13 stores the identification codes ID1 to ID4 of the sensor units SU1 to SU4 and the positions of the wheels W1 to W4 in a one-to-one correspondence in the memory 13a and thereafter included in the detection signal. It is determined as follows whether the various pieces of information on the tires are information on which of the wheels W1 to W4. First, when the detection signal is received via the receiver 11, the identification code included in the detection signal is compared with the identification code stored in the memory 13a, and this detection is performed based on the comparison result. It is determined from which sensor unit of each wheel W1 to W4 the signal is transmitted. Specifically, when the identification code included in the detection signal is ID1, it is determined that this detection signal is transmitted from the sensor unit of the right front wheel W1. Further, based on the determination result, a process for displaying various information on the tire included in the detection signal on the indicator 12 is performed. According to such a configuration, after the identification codes ID1 to ID4 of the sensor units SU1 to SU4 corresponding to the wheels W1 to W4 are determined, the detection signals are generated without forming the static magnetic fields M1 and M2. It is possible to determine which sensor unit of the wheels W1 to W4 is transmitted. Therefore, it is not necessary to energize the bar antennas 14a and 15a, so that power consumption as a system can be reduced.

  On the other hand, a tire mounted on a vehicle is usually rotated (position exchange) in accordance with, for example, the travel distance of the vehicle in order to make the wear uniform and extend the life. Here, when such rotation is performed, the positions of the sensor units SU1 to SU4 change, and thus the tire location registration process described above needs to be executed again. In this regard, according to the tire pressure monitoring system according to the present embodiment, the tire location registration process is automatically executed every time the vehicle-mounted engine 17 is started without manual operation by the driver. Will be improved.

As described above, according to the tire pressure monitoring system according to the present embodiment, the following effects can be obtained.
(1) The magnetic field directions at the right wheels W1, W3 and the left wheels W2, W4 are different from each other when viewed from the respective wheels, and the magnetic field strengths at the front wheels W1, W2 and the rear wheels W3, W4 are different from each other. The static magnetic fields M1 and M2 are selectively formed by the bar antennas 14a and 15a. Further, in the sensor units SU1 to SU4, information on the magnetic field detected through the magnetic sensor 27 is included in the detection signal and transmitted. Based on the magnetic field information included in the detection signal and the energization state of the bar antennas 14a and 15a, it is determined from which sensor unit of each of the wheels W1 to W4 this detection signal is transmitted. I decided to distinguish. As a result, it is possible to determine which tire of each of the wheels W1 to W4 has an abnormality while omitting the initiator and its wiring system from the system and simplifying the configuration.

  (2) The direction of the magnetic field in the right wheels W1, W3 is the first direction from the outside of the vehicle to the inside along the rotation axes W1a, W3a, and the direction of the magnetic field in the left wheels W2, W4 is those The static magnetic fields M1 and M2 are formed along the rotation axes W2a and W4a in the second direction from the inside to the outside of the vehicle. Thereby, even if the sensor units SU1 to SU4 rotate with the rotation of the wheels W1 to W4, the direction of the magnetic field in the sensor units SU1 to SU4 becomes difficult to change, so the right wheels W1, W3 and the left wheels W2, It becomes possible to determine with high accuracy which tire of W4 has an abnormality.

  (3) In forming the static magnetic fields M1 and M2, the bar antennas 14a and 15a used in the electronic key system are used as electromagnets. As a result, it is not necessary to newly provide an electromagnet, so that the cost can be further reduced.

  (4) When it is determined from which sensor unit of each wheel the detection signal is transmitted, the identification code included in the detection signal and the position of each wheel W1 to W4 based on the determination result Are stored in the memory 13a in a one-to-one correspondence. Then, the positions of all the wheels W1 to W4 and the identification codes ID1 to ID4 of the sensor units SU1 to SU4 are stored in the memory 13a in a one-to-one correspondence, and thereafter the identification code and the memory included in the detection signal are stored. Based on the comparison with the identification code stored in 13a, it is determined whether the various types of tire information included in the detection signal indicate the information of which tire of each wheel. This eliminates the need to energize the bar antennas 14a and 15a after the identification codes of the sensor units SU1 to SU4 corresponding to the wheels W1 to W4 are determined, thereby reducing power consumption as a system. Will be able to.

  (5) The tire location registration process is executed every time the in-vehicle engine 17 is started. As a result, the tire location registration process is automatically executed without any manual operation by the driver, so that the convenience of the driver is improved.

  (6) The detection signals from the sensor units SU1 to SU4 are transmitted spontaneously. This eliminates the need to provide an initiator for transmitting a trigger signal for requesting transmission of a detection signal to the sensor unit as in the conventional system, so that the number of parts and the cost can be reduced. Become.

(Second Embodiment)
Next, a second embodiment of the tire pressure monitoring system according to the present invention will be described with reference to FIGS. The tire air pressure monitoring system according to the second embodiment also has a basic structure similar to that shown in FIG. 1, and here, as a diagram corresponding to FIG. The system configuration is shown in FIG. In FIG. 10, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. Hereinafter, differences between the two will be mainly described.

  As shown in FIG. 10, in the tire pressure monitoring system according to the present embodiment, a static magnetic field is formed only by the front-side bar antenna 14a among the bar antennas 14a and 15a described above. Further, the magnetic field strength of the static magnetic field M1 formed by the antenna 14a is increased by appropriately changing the energization amount to the front bar antenna 14a. And the magnetic field is applied to all the wheels W1 to W4 by forming the static magnetic field M1 having such a strong magnetic field strength. At this time, the magnetic field strength at the front wheels W1 and W2 becomes larger than the first threshold value B21, and the magnetic field strength at the rear wheels W3 and W4 becomes larger than the second threshold value B22 (<B1).

  On the other hand, the sensor units SU1 to SU4 in the present embodiment are configured so that when the magnetic field intensity detected through the magnetic field intensity detection unit 27a exceeds the first threshold value B21 or exceeds the second threshold value B22. The detection signal is transmitted. That is, in this embodiment, if the static magnetic field M1 is formed by the front bar antenna 14a, detection signals are transmitted from all the sensor units SU1 to SU4.

  Incidentally, a conventional sensor unit usually has an antenna, and is configured to transmit a detection signal by receiving the command signal transmitted from the above-described initiator via the antenna. On the other hand, in the present embodiment, since the sensor units SU1 to SU4 transmit detection signals only by applying a magnetic field to the sensor units SU1 to SU4 without incorporating antennas, the sensor units SU1 to SU4 The structure can be simplified.

The information on the magnetic field included in the detection signal is set based on the output signal of the magnetic sensor 27 with the bit strings shown in the following (c1) to (c4).
(C1) In a situation where a detection signal is transmitted on condition that the magnetic field intensity detected through the magnetic field intensity detection unit 27a reaches the first threshold value B21, the direction of the magnetic field detected through the magnetic field direction detection unit 27b is the tire. When having a component in the direction opposite to the protruding direction of the valve 22. In this case, the magnetic field information is set to the bit string “10”.

  (C2) In a situation where a detection signal is transmitted on condition that the magnetic field intensity detected through the magnetic field intensity detection unit 27a reaches the first threshold value B21, the direction of the magnetic field detected through the magnetic field direction detection unit 27b is the tire. A component having the same direction as the protruding direction of the valve 22. In this case, the magnetic field information is set to the bit string “01”.

  (C3) In a situation where a detection signal is transmitted on condition that the magnetic field strength detected through the magnetic field strength detection unit 27a reaches the second threshold B22, the direction of the magnetic field detected through the magnetic field direction detection unit 27b is the tire. When having a component in the direction opposite to the protruding direction of the valve 22. In this case, the magnetic field information is set to the bit string “11”.

  (C4) In a situation where a detection signal is transmitted on condition that the magnetic field intensity detected through the magnetic field intensity detection unit 27a reaches the second threshold B22, the direction of the magnetic field detected through the magnetic field direction detection unit 27b is the tire. A component having the same direction as the protruding direction of the valve 22. In this case, the magnetic field information is set to the bit string “00”.

Such a configuration as the sensor unit is the same for the sensor units SU2 to SU4.
By the way, if each sensor unit SU1-SU4 is comprised in this way, if the static magnetic field M1 was formed with the front side bar antenna 14a, the detection signal transmitted from the sensor units SU1-SU4 of each wheel W1-W4 will be: As shown in FIG. 10, the signal includes bit strings “11”, “00”, “10”, and “01” as magnetic field information. That is, the magnetic field information included in the detection signal is different from each other depending on the position of the wheel on which each sensor unit SU1 to SU4 is disposed. Based on this, it is possible to determine from which sensor unit of each wheel the detection signal is transmitted.

  Therefore, in the present embodiment, based on the information of the magnetic field included in the detection signal, the tire is determined while determining from which sensor unit of each of the wheels W1 to W4 the detection signal is transmitted. The location registration process is executed. Note that the system controller 13 performs the tire location registration process as a static magnetic field forming process as described above, during a period from when the on-vehicle engine 17 is started until a predetermined time elapses. The process which forms the static magnetic field M1 by supplying with electricity to 14a is performed.

  FIG. 11 is a diagram corresponding to FIG. 7 described above, and shows a processing procedure of tire location registration processing executed through the system control device 13 in the present embodiment in a flowchart. In FIG. 11, the same processes as those in FIG. 7 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 11, in the tire location registration process of the present embodiment, when it is determined in the process of step S24 that the magnetic field information included in the detection signal is not the bit string “00” ( Step S24: NO), it is determined whether or not the information of the magnetic field is a bit string “10” (Step S30). Here, when the magnetic field information included in the detection signal is the bit string “10” (step S30: YES), it is determined that this detection signal is transmitted from the sensor unit of the right rear wheel W3. Then, the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the right rear wheel W3 (step S31). Subsequently, various pieces of tire information included in the detection signal are displayed on the indicator 12 as information on the right rear wheel W3 (step S32), and the system control device 13 ends this series of processing.

  On the other hand, when it is determined in the process of step 30 that the magnetic field information included in the detection signal is not the bit string “10” (step S30: NO), that is, when the magnetic field information is the bit string “01”. Is determined that the detection signal is transmitted from the sensor unit of the left rear wheel W4, and the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the left rear wheel W4. (Step S33). Further, various pieces of tire information included in the detection signal are displayed on the indicator 12 as tire information of the left rear wheel W4 (step S34), and the system control device 13 ends this series of processing.

  Even with such a configuration as a tire pressure monitoring system, it is possible to display the tire information of the wheels W1 to W4 on the indicator 12 while omitting the initiator and the wiring system provided in the conventional system. become. For this reason, it becomes possible to determine through the indicator 12 which tire of each of the wheels W1 to W4 has an abnormality.

  As described above, according to the present embodiment, in addition to the effects (2) to (5) according to the first embodiment, the effects in place of the effects (1) and (6) above can be obtained. The following effects can be obtained.

  (7) The magnetic field directions at the right wheels W1, W3 and the left wheels W2, W4 are different from each other when viewed from the respective wheels, and the magnetic field strengths at the front wheels W1, W2 and the rear wheels W3, W4 are different from each other. The static magnetic field M1 is formed by the front bar antenna 14a. Further, in the sensor units SU1 to SU4, information on the magnetic field detected through the magnetic sensor 27 is included in the detection signal and transmitted. And based on the information of the magnetic field contained in a detection signal, it was made to discriminate | determine from which sensor unit of each wheel W1-W4 this detection signal was transmitted. Thus, it is possible to determine which tire of each of the wheels W1 to W4 has an abnormality while omitting the initiator and its wiring system from the system and simplifying the configuration.

  (8) The detection signals are transmitted from the sensor units SU1 to SU4 based on the magnetic field intensity detected through the magnetic field intensity detector 27a. Thereby, since it is not necessary to incorporate an antenna in the sensor unit as in the conventional tire pressure monitoring system, the structure of the sensor units SU1 to SU4 can be simplified.

(Third embodiment)
Next, a third embodiment of the tire pressure monitoring system according to the present invention will be described with reference to FIGS. Note that the basic structure of the tire pressure monitoring system according to the third embodiment is similar to the structure shown in FIG. 10, and here, as a diagram corresponding to FIG. The system configuration is shown in FIG. In FIG. 12, the same elements as those shown in FIG. 10 are denoted by the same reference numerals, and redundant description is omitted. Hereinafter, differences between the elements will be mainly described.

  In the tire pressure monitoring system according to the present embodiment, the magnetic field strength of the static magnetic field M1 formed by the antenna 14a is increased or decreased by appropriately changing the energization amount to the front bar antenna 14a. Specifically, when the magnetic field strength of the static magnetic field M1 is increased, the static magnetic field illustrated in FIG. 10 is formed. On the other hand, when the magnetic field strength of the static magnetic field M1 is weakened, the magnetic field is applied only to the front wheels W1, W2, as shown in FIG. In the situation where the magnetic field strength of the static magnetic field M1 is weakened, the magnetic field strength in the front wheels W1, W2 is set to be larger than the second threshold value B22.

  On the other hand, the sensor units SU1 to SU4 in the present embodiment are configured to transmit the detection signal when the magnetic field intensity detected through the magnetic field intensity detection unit 27a exceeds the second threshold B22.

The magnetic field information included in the detection signal is set in the bit string shown in the following (d1) and (d2) based on the output signal of the magnetic sensor 27.
(D1) The direction of the magnetic field detected through the magnetic field direction detector 27b has a component in the direction opposite to the protruding direction of the tire valve 22. In this case, the magnetic field information is set to the bit string “11”.

  (D2) When the direction of the magnetic field detected through the magnetic field direction detector 27b has a component in the same direction as the protruding direction of the tire valve 22. In this case, the magnetic field information is set to the bit string “00”.

Such a configuration as the sensor unit is the same for the sensor units SU2 to SU4.
By the way, if each of the sensor units SU1 to SU4 is configured in this way, if the static magnetic field M1 having a weak magnetic field strength as illustrated in FIG. 12 is formed by the front side bar antenna 14a, the sensors of the front wheels W1 and W2 A detection signal is transmitted only from the units SU1 and SU2. Therefore, when the detection signal is received via the receiver 11, it can be determined that the detection signal is transmitted from the sensor units SU1 and SU2 of the front wheels W1 and W2. The system control device 13 can grasp the identification codes ID1, ID2 of the sensor units SU1, SU2 of W2.

  On the other hand, if a static magnetic field M1 having a strong magnetic field strength as illustrated in FIG. 10 is formed by the front bar antenna 14a, detection signals are transmitted from all the sensor units SU1 to SU4. However, at this time, if the identification codes ID1 and ID2 of the sensor units SU1 and SU2 of the front wheels W1 and W2 are already known, detection signals including other identification codes are sent from the sensor units SU3 and SU4 of the rear wheels W3 and W4. It is possible to determine that it has been transmitted. That is, if the identification codes ID1 and ID2 of the sensor units SU1 and SU2 of the front wheels W1 and W2 can be discriminated in advance, it is determined whether the detection signal is transmitted from the sensor units SU3 and SU4 of the rear wheels W3 and W4. Can be discriminated automatically.

  Therefore, in the present embodiment, as the static magnetic field forming process, first, the front bar antenna 14a is energized for a period until a predetermined time elapses from the time when the on-vehicle engine 17 is started, and the previous FIG. The static magnetic field M1 having a low magnetic field strength exemplified in (1) is formed. Then, after a predetermined time has elapsed, the front-side bar antenna 14a is energized this time so that the static magnetic field M1 having a strong magnetic field exemplified in FIG. 10 is formed for a predetermined time.

On the other hand, in the present embodiment, the following two processes shown in (e1) and (e2) are executed as the tire location registration process.
(E1) Front-side tire location registration processing that is repeatedly executed with a predetermined calculation period during a period in which the static magnetic field M1 having a weak magnetic field intensity is formed through the static magnetic field formation processing.

(E2) Rear-side tire location registration process that is repeatedly executed with a predetermined calculation period during the period in which the static magnetic field M1 having a strong magnetic field intensity is formed through the static magnetic field forming process.
The former front-side tire location registration process is the same as the process illustrated in FIG. That is, the system controller 13 stores the identification codes of the sensor units SU1 and SU2 of the front wheels W1 and W2 in the memory 13a through the front side tire location registration process, and the tire information of the front wheels W1 and W2 as the indicator. 12 is displayed.

FIG. 13 is a flowchart showing a processing procedure of rear tire location registration processing executed through the system control device 13.
As shown in FIG. 13, in the rear tire location registration process, first, it is determined whether or not a detection signal has been received via the receiver 11 (step S40). If the detection signal is received (step S40: YES), the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the front wheels W1 and W2 as the processing of the subsequent step S41. It is determined whether or not. Here, when the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the front wheels W1 and W2 (step S41: YES), this detection signal is sent to the front wheels W1 and W2. The system control device 13 determines that it is transmitted from the sensor unit, and ends this series of processing.

  On the other hand, when the identification code included in the detection signal is not stored in the memory 13a as the identification code of the sensor unit of the front wheels W1 and W2 in the process of step S41 (step S41: NO), the following step S42 As a process of (1), it is determined whether or not the magnetic field information included in the detection signal is a bit string “11” (step S42). Here, when the magnetic field information included in the detection signal is the bit string “11” (step S42: YES), it is determined that this detection signal is transmitted from the sensor unit of the right rear wheel W3. Then, the identification code included in the detection signal is stored in the memory 13a as the identification code of the sensor unit of the right rear wheel W3 (step S43). Subsequently, various pieces of tire information included in the detection signal are displayed on the indicator 12 as tire information of the right rear wheel W3 (step S44), and the system control device 13 ends this series of processing.

  On the other hand, in the process of step S42, when the magnetic field information included in the detection signal is not the bit string “11” (step S42: NO), that is, the magnetic field information included in the detection signal is the bit string “00”. ”, It is determined that the detection signal is transmitted from the sensor unit of the left rear wheel W4, and the identification code included in the detection signal identifies the sensor unit of the left rear wheel W4. The code is stored in the memory 13a (step S45). Subsequently, various types of tire information included in the detection signal are displayed on the indicator 12 as tire information of the left rear wheel W4 (step S44), and the system control device 13 ends this series of processing.

  Even with such a configuration as a tire pressure monitoring system, it is possible to display the tire information of the wheels W1 to W4 on the indicator 12 while omitting the initiator and the wiring system provided in the conventional system. become. For this reason, it becomes possible to determine through the indicator 12 which tire of each of the wheels W1 to W4 has an abnormality.

  As described above, according to the present embodiment, in addition to the effects (2) to (5) and (8) according to the first and second embodiments, the above (1) and ( The following effects can be obtained instead of the effects of 7).

  (9) The detection signals are transmitted from the sensor units SU1 to SU4 on condition that the magnetic field intensity detected through the magnetic field intensity detection unit 27a exceeds the second threshold B22. Further, the static magnetic field M1 having a weak magnetic field strength is formed by the front-side bar antenna 14a, so that only the magnetic field strength in the front wheels W1, W2 is set to be equal to or higher than the second threshold B22. When a detection signal is received via the receiver 11 while the static magnetic field M1 having a weak magnetic field strength is formed by the front bar antenna 14a, the detection signal is received from the sensor units SU1 and SU2 of the front wheels W1 and W2. It was determined that it was sent. Further, based on the magnetic field information included in the detection signal, it is determined whether the detection signal is transmitted from the right wheel or the left wheel sensor unit. Thus, it is possible to determine which tire of each of the wheels W1 to W4 has an abnormality while omitting the initiator and its wiring system from the system and simplifying the configuration.

(Other embodiments)
In addition, each said embodiment can also be implemented with the following forms which changed these suitably.
In the first embodiment, the detection signals are spontaneously transmitted from the sensor units SU1 to SU4. Instead, for example, as in the second and third embodiments, the magnetic field intensity detection unit The detection signal may be transmitted based on the magnetic field intensity detected through 27a.

  In the second embodiment, the static magnetic field M1 is formed by using the front bar antenna 14a as an electromagnet. Instead, for example, the static magnetic field M1 is formed by using a permanent magnet. You may do it. In this case, it is effective to configure the sensor units SU1 to SU4 as follows. First, the sensor units SU1 to SU4 are configured to spontaneously transmit detection signals as in the first embodiment. In the magnetic field information setting process shown in the above (c1) to (c4), the magnetic field intensity detected through the magnetic field intensity detector 27a is equal to or higher than the first threshold B21, or equal to or higher than the second threshold B22. To do based on what is.

  In the second and third embodiments, the static magnetic field is formed only by the front bar antenna 14a. Instead, for example, the static magnetic field is formed only by the rear bar antenna 15a. Also good.

  In the second and third embodiments, as a condition for transmitting detection signals from the sensor units SU1 to SU4, the magnetic field intensity detected through the magnetic field intensity detection unit 27a reaches the first threshold B21. Alternatively, the condition is that the second threshold B22 is reached, but instead of this, for example, any one of the following conditions (f1) to (f3) may be adopted.

  (F1) The magnetic field intensity detected through the magnetic field intensity detector 27a changes with a predetermined pattern. Specifically, as shown in FIGS. 14A and 14B, for example, the output signal V of the magnetic field strength detection unit 27a is binarized based on the threshold voltage Vth through a comparator. The threshold voltage Vth is set based on the first and second threshold values B21 and B22 set for the magnetic field strength. The condition is that the binarized signal A changes with a predetermined pattern.

  (F2) The intensity detected through the magnetic field intensity detector 27a exceeds the first threshold B21 or the second threshold B22, and the acceleration detected through the acceleration sensor 25 exceeds a predetermined value.

(F3) The conditions of (f1) and (f2) are satisfied respectively.
According to such a configuration, for example, it is possible to avoid a situation in which the detection signal is erroneously transmitted in a situation where magnets are present near the sensor units SU1 to SU4. Become. In short, any sensor unit SU1 to SU4 may transmit the detection signal based on the magnetic field intensity detected through the magnetic field intensity detection unit 27a.

  In the second and third embodiments and the modifications thereof, the sensor units SU1 to SU4 transmit detection signals based on the magnetic field strength detected through the magnetic field strength detection unit 27a. For example, spontaneous transmission of a detection signal may be started based on the magnetic field strength detected through the magnetic field strength detection unit 27a. That is, the sensor units SU1 to SU4 may be activated / stopped based on the magnetic field strength detected through the magnetic field strength detection unit 27a. As a condition for stopping the operation of the sensor units SU1 to SU4, for example, the condition that the magnetic field intensity detected through the magnetic field intensity detector 27a reaches a predetermined threshold after transmitting the detection signal may be used. It is.

  -Sensor unit SU1-SU4 may transmit a detection signal on condition that the trigger signal transmitted from the initiator mentioned above is received. According to such a configuration, if the trigger signal is transmitted from the initiator, the detection signal is immediately transmitted from the sensor units SU1 to SU4. Therefore, the response of the sensor units SU1 to SU4 is compared with the above-described spontaneous sensor unit. Can be improved. However, in this case, it is necessary to provide at least one initiator in the vehicle.

  In each of the above embodiments, the tire location registration process is executed every time the in-vehicle engine 17 is started. However, for example, it may be executed after a predetermined time has elapsed since the in-vehicle engine 17 was started. .

  In each of the above embodiments, the process of storing the identification codes of the sensor units SU1 to SU4 of the wheels W1 to W4 in the memory 13a is performed, but the process can be omitted. In this case, each time the detection signal is received via the receiver 11, the detection signal is transmitted from any sensor unit SU1 to SU4 of each wheel W1 to W4 based on the magnetic field information included in the detection signal. What is necessary is just to discriminate | determine.

  In each of the above embodiments, by forming the static magnetic fields M1 and M2 with the bar antennas 14a and 15a, the direction of the magnetic field in the right wheels W1 and W3 is set to the first direction from the outside to the inside of the vehicle, and The direction of the magnetic field in the left wheels W2, W4 was set to the second direction from the inside to the outside of the vehicle. Instead, for example, the direction of the magnetic field in the right wheels W1, W3 is set to the direction from the inside of the vehicle to the outside, and the direction of the magnetic field in the left wheels W2, W4 is set to the direction from the outside of the vehicle to the inside. May be. In short, the direction of the magnetic field in each of the wheels W1 to W4 only needs to be set so as to have a component parallel to the direction along the rotation axis. Even with such a configuration, it is possible to determine whether the detection signal is transmitted from the sensor unit of the right wheel or the left wheel.

  In each of the above embodiments, the static magnetic fields M1 and M2 are formed using the bar antennas 14a and 15a of the electronic key system. Instead, for example, a new bar antenna is provided in the vehicle. The static magnetic fields M1 and M2 may be formed using this bar antenna. Such a configuration is particularly effective for a vehicle not equipped with an electronic key system.

In each of the above embodiments, the Hall element is adopted as the magnetic detection element for detecting the magnetic field applied to the sensor units SU1 to SU4. For example, the resistance is generated by the magnetoresistive effect according to the applied magnetic field. You may employ | adopt the magnetoresistive effect (MRE) element from which a value changes.
(Appendix)
Next, a technical idea that can be grasped from the above embodiment and its modifications will be additionally described.

  (A) In the tire pressure monitoring system according to claim 4, the magnet is mounted on either the front wheel or the rear wheel so as to form a static magnetic field such that the magnetic field strengths of the front wheel and the rear wheel are different from each other. A tire pressure monitoring system characterized by being arranged closer to one side. According to this system, the magnetic field strength at each of the front and rear wheels becomes different from each other only by arranging the magnets closer to one of the front and rear wheels. Therefore, the invention according to claim 4 is easily realized. Will be able to.

  (B) The tire pressure monitoring system according to claim 9, wherein the tire location registration process is executed every time the vehicle-mounted engine is started. In general, a tire mounted on a vehicle is rotated (position exchange) in accordance with, for example, the travel distance of the vehicle in order to make the wear uniform and extend the life. Here, when such rotation is performed, the position of the sensor unit is changed, so that the tire location registration process described above needs to be executed again. In this regard, if the tire location registration process is executed every time the vehicle-mounted engine is started as in the above system, the process is automatically performed without the manual operation of the driver. Will be improved.

  (C) In the tire pressure monitoring system according to any one of claims 1 to 9, appendix i, and appendix b, the vehicle transmits a trigger signal requesting transmission of the detection signal to the sensor unit. The tire pressure monitoring system is characterized in that one initiator is provided, and the sensor unit transmits the detection signal based on reception of the trigger signal. According to the system, it is possible to freely adjust the timing at which the detection signal is transmitted from the sensor unit simply by adjusting the timing at which the trigger signal is transmitted from the initiator, so that the degree of freedom in designing the system is improved. Will be able to.

  (D) In the tire pressure monitoring system according to claim 11, switching of the operation state of the sensor unit is performed based on a change in magnetic field intensity detected through the magnetic detection element with a predetermined pattern. Features tire pressure monitoring system. According to the system, it is possible to avoid a situation in which the operation state is switched only when an object that generates magnetism comes close to the sensor unit, and thus it is possible to prevent malfunction of the sensor unit. It becomes like this.

  (E) In the tire pressure monitoring system according to any one of claims 11 and D, the sensor unit further includes an acceleration sensor for detecting a centrifugal acceleration of the tire, and is detected through the magnetic detection element. The tire pressure monitoring system is characterized in that the operation state of the tire is switched based on the centrifugal acceleration of the tire detected through the acceleration sensor in addition to the magnetic field strength. According to the system, it is possible to avoid a situation in which the operation state is switched only when an object that generates magnetism comes close to the sensor unit, and thus it is possible to prevent malfunction of the sensor unit. It becomes like this.

  (F) In the tire pressure monitoring system according to any one of claim 11, appendix d, and appendix e, the sensor unit receives the detection signal before the predetermined time elapses after receiving the detection signal. A tire pressure monitoring system, wherein transmission of the detection signal is stopped based on detection of a magnetic field strength of a predetermined threshold value or more through a detection element. According to the system, it is possible to avoid a situation in which the operation state is switched only when an object that generates magnetism comes close to the sensor unit, and thus it is possible to prevent malfunction of the sensor unit. It becomes like this.

    B ... detection area, M1, M2 ... static magnetic field, W1 ... right front wheel, W2 ... left front wheel, W3 ... right rear wheel, W4 ... left rear wheel, SU1-SU4 ... sensor unit, W1a-W4a ... rotating shaft, 11, 32 ... Receiver, 12, 34 ... Indicator, 12a ... Warning lamp, 12b ... Display unit, 13 ... System controller, 13a ... Memory, 14 ... Transmitter, 14a ... Front side bar antenna, 15 ... Transmitter, 15a ... Rear side bar antenna, 16 ... engine switch, 17 ... in-vehicle engine, 20 ... portable device, 21 ... unit body, 21a ... air hole, 21b ... sensor hole, 22 ... tire valve, 23 ... air pressure sensor, 24 ... temperature sensor, 25 ... Acceleration sensor, 26 ... Battery level sensor, 27 ... Magnetic sensor, 27a ... Magnetic field intensity detector, 27b ... Magnetic field direction detector, 28 ... Sensor unit controller, 9 ... transmitter, 30 a to 30 d ... initiator, 31 a to 31 d ... sensor unit, 33 ... control unit.

Claims (12)

A sensor unit is provided on each wheel of the vehicle to detect the tire air pressure and wirelessly transmit a detection signal including information on the detected air pressure. Based on the air pressure information included in the detection signal In the tire pressure monitoring system for monitoring the tire pressure of each wheel,
The sensor unit includes a magnet that forms a static magnetic field to apply a different magnetic field to each wheel, and the sensor unit includes a magnetic detection element that detects the applied magnetic field, and a magnetic field detected through the magnetic detection element. Information is included in the detection signal and transmitted, and based on the magnetic field information included in the detection signal, which sensor unit of each wheel transmits the detection signal The tire air pressure monitoring system is characterized in that the tire air pressure of each wheel is monitored while discriminating the tire pressure. The magnet forms, as the static magnetic field, a static magnetic field in which the directions of the magnetic fields in each of the right wheel and the left wheel of the wheels are different from each other when viewed from the respective wheels. The sensor unit is configured to transmit, as information on the magnetic field, information on the direction of the magnetic field detected through the magnetic detection element included in the detection signal, and the direction of the magnetic field included in the detection signal. The tire air pressure according to claim 1, wherein the tire air pressure of each wheel is monitored while determining whether the detection signal is transmitted from the sensor unit of the right wheel or the left wheel based on the information. Monitoring system. The magnets have different magnetic field directions on the right wheel and the left wheel, respectively, so that the magnetic field directions on the right wheel and the left wheel are different from each other when viewed from the respective wheels. The static magnetic field which becomes the 1st direction which goes to the inside from the outside of the vehicle along those axis of rotation, and the 2nd direction which goes to the outside from the inside of the vehicle is formed. Tire pressure monitoring system. The magnet forms a static magnetic field such that the magnetic field strengths of the front wheels and the rear wheels of the wheels are different from each other as the static magnetic field, and the sensor unit uses the magnetic field information as Information on the magnetic field intensity detected through the magnetic detection element is transmitted in the detection signal, and based on the information on the magnetic field intensity included in the detection signal, the detection signal is transmitted to the front wheels and The tire pressure monitoring system according to any one of claims 1 to 3, wherein the tire air pressure of each of the wheels is monitored while determining which sensor unit of the rear wheel is transmitted. The magnets form a static magnetic field in which the directions of the magnetic fields of the right wheel and the left wheel of the front wheels are different from each other when viewed from the respective wheels, and the magnetic field strength of each wheel is a predetermined value or more. A static magnetic field is formed such that the direction of the magnetic field on the right and left wheels of the rear wheel is different from each other when viewed from the respective wheels, and the magnetic field strength at each wheel is greater than or equal to a predetermined value. And a second electromagnet that
By selectively energizing the first and second electromagnets, the magnetic field strength in one of the front wheel and the rear wheel is set to the predetermined value or more, and the detection signal is the front wheel and the Discrimination from which sensor unit of the rear wheel is transmitted is performed based on the energization state of the first and second electromagnets and the information on the magnetic field strength included in the detection signal. The tire pressure monitoring system according to claim 4. The sensor unit transmits the detection signal on condition that a magnetic field intensity equal to or higher than a predetermined threshold is detected through the magnetic detection element,
The magnet is constituted by a third electromagnet that forms a static magnetic field such that the magnetic field strength in any one of the front wheels and the rear wheels of the wheels is equal to or greater than the threshold value.
The detection signal is transmitted from any sensor unit of the front wheel or the rear wheel, with the magnetic field strength in one of the front wheel or the rear wheel being set to the threshold value or more through energization of the third electromagnet. The tire pressure monitoring system according to any one of claims 1 to 3, wherein the determination as to whether the vehicle is a vehicle is based on whether the magnetic field strength of the front wheel or the rear wheel is greater than or equal to the threshold value. The tire pressure monitoring system according to any one of claims 1 to 4, wherein the magnet is an electromagnet that forms the static magnetic field when energized. The tire pressure monitoring system according to any one of claims 5 to 7, wherein the electromagnet is a diversion of a bar antenna provided in a vehicle interior to constitute an electronic key system provided in a vehicle. The sensor unit, when transmitting the detection signal, includes a unique identification code registered in advance and transmits the detection signal,
When it is determined from which sensor unit of each wheel the detection signal is transmitted, the identification code included in the detection signal and the position of each wheel are determined based on the determination result. The tire location registration process stored in the storage means in a one-to-one correspondence is performed, and all the wheel positions and the sensor unit identification codes are stored in the storage means in a one-to-one correspondence. Based on the comparison between the identification code included in the signal and the identification code stored in the storage means, the air pressure information included in the detection signal indicates the tire pressure of any of the wheels. The tire air pressure monitoring system according to any one of claims 1 to 8, wherein the tire air pressure of each wheel is monitored while determining whether or not the tire pressure is. The tire pressure monitoring system according to any one of claims 1 to 9, wherein the sensor unit spontaneously transmits the detection signal. The tire pressure monitoring system according to any one of claims 1 to 10, wherein the sensor unit switches its operation state based on information on a magnetic field detected through the magnetic detection element. A sensor unit is provided on each wheel of the vehicle to detect the tire air pressure and wirelessly transmit a detection signal including information on the detected air pressure. Based on the air pressure information included in the detection signal In the tire pressure detecting method for detecting the tire pressure of each wheel,
A magnet for forming a static magnetic field to apply a different magnetic field to each wheel;
After detecting the magnetic field applied to each wheel through the sensor unit, information on the detected magnetic field is included in the detection signal and transmitted from the sensor unit, and information on the magnetic field included in the detection signal is included. The tire air pressure detection method according to claim 1, wherein the tire air pressure of each wheel is detected while determining from which sensor unit of each wheel the detection signal is transmitted.

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