JP2018047851A - Tire air pressure monitoring system and detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire air pressure monitoring system, which allows a monitoring device and a detecting device to perform two-way communication without adjusting rotation angles of tires during stopping of a vehicle, and yet can suppress consumed power by the detecting device.SOLUTION: A tire air pressure monitoring system comprises a detecting device that detects air pressure of tires provided in a vehicle C and transmits via radio waves air pressure signals obtained by the detection, and a monitoring device that receives the air pressure signals to monitor air pressure of each tire. The monitoring device 1 comprises a request signal transmitting portion that transmits via radio waves request signals for requesting the air pressure signals to the detecting device 2. The detecting device 2 comprises: a request signal receiving portion that receives request signals transmitted from the monitoring system 1; a rotation angle detecting portion that detects rotation angles of the tires 3; a sensitivity setting portion that sets reception sensitivity of the request signal receiving portion according to rotation angles detected by the rotation angle detecting portion; and an air pressure signal transmitting portion that transmits the air pressure signals when the request signal receiving portion receives the request signals.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire pressure monitoring system and a detection device.

  There is a tire pressure monitoring system (TPMS) that detects the air pressure of a tire provided in a vehicle and issues a warning to a user when the detected air pressure is abnormal. The tire pressure monitoring system includes a detection device provided for each tire and a monitoring device disposed on the vehicle body. The detection device detects the air pressure of the tire and wirelessly transmits the air pressure signal obtained by the detection using radio waves in the UHF band. The monitoring device receives the air pressure signal transmitted from each detection device, and monitors the air pressure of each tire based on the received air pressure signal. When there is an abnormality in the tire air pressure, the monitoring device displays a warning on the tire air pressure abnormality and issues a warning.

There are two types of communication methods in the tire pressure monitoring system: a unidirectional method in which the detection device spontaneously transmits an air pressure signal, and a bidirectional method in which the detection device transmits an air pressure signal in response to a request from the monitoring device. is there. When the vehicle is stopped, the bidirectional method is suitable.
Since the detection device is driven by a battery, the reception sensitivity of the request signal and the strength of the air pressure signal are set as small as possible in order to reduce power consumption. Also in the monitoring device, it is desirable to reduce the power consumption by setting the signal strength of the request signal and the reception sensitivity of the air pressure signal low. Then, a rotation angle range in which the request signal does not reach the detection device is generated depending on the positional relationship between the monitoring device and the detection device when the vehicle is stopped, that is, the rotation angle of the tire. Similarly, a range of rotational angles occurs where the air pressure signal does not reach the monitoring device.

  Patent Document 1 discloses a technique for detecting a rotational position of a tire and guiding the vehicle to a stop position where the rotational position does not hinder communication between the monitoring device and the detection device.

Japanese Patent Laying-Open No. 2015-20482

  However, in Patent Document 1, the user has to move the vehicle according to the guidance and adjust the rotation angle of the tire, and there is a problem that the tire air pressure cannot be detected while the vehicle is completely stopped. It was.

  An object of the present invention is to provide a tire pressure monitoring system in which the monitoring device and the detection device can perform two-way communication without adjusting the rotation angle of the tire when the vehicle is stopped, and the power consumption of the detection device can be suppressed. And providing a detection device.

  The tire pressure monitoring system according to this aspect is provided in a tire of a vehicle, and a detection device that wirelessly transmits a pressure signal obtained by detecting the pressure of the tire, and the pressure signal transmitted from the detection device. A tire pressure monitoring system including a monitoring device that receives and monitors the tire air pressure, the monitoring device including a request signal transmission unit that wirelessly transmits a request signal for requesting the air pressure signal to the detection device. The detection device includes a request signal receiving unit that receives the request signal transmitted from the monitoring device, a rotation angle detection unit that detects a rotation angle of the tire, and a rotation detected by the rotation angle detection unit. A sensitivity setting unit that sets the reception sensitivity of the request signal receiving unit according to an angle, and the air pressure signal is transmitted when the request signal is received by the request signal receiving unit. And a that pneumatic signal transmitter.

  The detection device according to this aspect is a detection device that is provided in a tire of a vehicle and wirelessly transmits a pneumatic signal obtained by detecting the pneumatic pressure of the tire, and receives a request signal for requesting the pneumatic signal. A request signal receiver, a rotation angle detector that detects the rotation angle of the tire, and a sensitivity setting unit that sets the reception sensitivity of the request signal receiver according to the rotation angle detected by the rotation angle detector And a pneumatic signal transmitter that transmits the pneumatic signal when the request signal is received by the request signal receiver.

  Note that the present application can be realized not only as a tire pressure monitoring system, a monitoring device, and a detection device having such a characteristic configuration, but also as a tire pressure monitoring method using such characteristic processing as a step. The program can be realized as a program for causing a computer to execute such steps. Further, it may be realized as a semiconductor integrated circuit that realizes part or all of the tire pressure monitoring system, monitoring device or detection device, or may be realized as another system including the tire pressure monitoring system, monitoring device or detection device. it can.

  According to the above, the tire pressure monitoring system and the monitoring device and the detection device can perform two-way communication without adjusting the rotation angle of the tire when the vehicle is stopped, and the power consumption of the detection device can be suppressed. A detection device can be provided.

It is a conceptual diagram which shows the example of 1 structure of the tire pressure monitoring system which concerns on embodiment of this invention. It is a block diagram which shows one structural example of the monitoring apparatus. It is a conceptual diagram which shows an example of an identifier table. It is a block diagram which shows the example of 1 structure of a detection apparatus. It is a conceptual diagram which shows LF dead zone. It is a conceptual diagram which shows an example of a dead zone table. It is a flowchart which shows the process sequence of a monitoring apparatus. It is a flowchart which shows the process sequence of a detection apparatus.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described. Moreover, you may combine arbitrarily at least one part of embodiment described below.

(1) A tire air pressure monitoring system according to this aspect is provided in a tire of a vehicle, and a detection device that wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire, and the above-mentioned transmitted from the detection device A tire pressure monitoring system comprising a monitoring device that receives a pressure signal and monitors the tire pressure, wherein the monitoring device wirelessly transmits a request signal for requesting the pressure signal to the detection device. The detection device includes a request signal reception unit that receives the request signal transmitted from the monitoring device, a rotation angle detection unit that detects a rotation angle of the tire, and a detection by the rotation angle detection unit. A sensitivity setting unit that sets a receiving sensitivity of the request signal receiving unit according to the rotation angle, and the air pressure signal when the request signal is received by the request signal receiving unit. And a pneumatic signal transmitting section for transmitting.

In this aspect, the monitoring device transmits a request signal to the detection device with a signal intensity corresponding to the rotation angle of the tire, and the detection device transmits an air pressure signal to the detection device according to the request signal. The positional relationship between the monitoring device and the detection device changes depending on the rotation angle of the tire when the vehicle is stopped, and the intensity of the request signal that reaches the detection device also changes. When the detection sensitivity of the request signal in the detection device is low, it becomes difficult to receive the request signal depending on the rotation angle of the tire.
However, since the detection device can change the reception sensitivity of the request signal according to the rotation angle of the tire, the detection device can receive the request signal regardless of the rotation angle of the tire. Therefore, the detection device can set the reception sensitivity of the request signal to high sensitivity as necessary, and can suppress power consumption in the detection device.

(2) The detection device determines a rotation angle range in which the intensity of the request signal reaching the detection device is increased according to a rotation angle of the tire, and a rotation angle range in which the intensity of the request signal is reduced, A request signal dead zone angle storage unit that stores information for setting the reception sensitivity of the request signal is provided, and the sensitivity setting unit stores the rotation angle detected by the rotation angle detection unit and the request signal dead zone angle storage unit. If the rotation angle of the tire belongs to a rotation angle range in which the strength of the request signal is strong based on the information to be set, the reception sensitivity of the request signal receiving unit is set to low sensitivity, the rotation angle of the tire, A configuration in which the reception sensitivity of the request signal receiving unit is set to a high sensitivity is preferable when the request signal belongs to a rotation angle range in which the intensity of the request signal is weak.

  In this aspect, when the rotation angle of the tire belongs to the rotation angle range in which the request signal reaching the detection device is strong, the sensitivity setting unit sets the reception intensity of the request signal to low sensitivity. On the other hand, when the rotation angle of the tire belongs to a rotation angle range in which the request signal reaching the detection device becomes weak, the sensitivity setting unit sets the reception intensity of the request signal to high sensitivity. Therefore, the detection device can receive the request signal by setting the reception sensitivity of the request signal to high sensitivity as necessary, and can transmit the air pressure signal to the monitoring device in response to the request of the monitoring device. it can.

(3) It is preferable that the detection device includes a signal strength setting unit that sets a signal strength transmitted by the air pressure signal transmission unit in accordance with the rotation angle detected by the rotation angle detection unit.

  In this aspect, the detection device transmits an air pressure signal to the monitoring device with a signal intensity corresponding to the rotation angle of the tire. The positional relationship between the monitoring device and the detection device changes depending on the rotation angle of the tire when the vehicle is stopped, and the intensity of the air pressure signal reaching the monitoring device also changes. However, since the detection device can change the signal strength of the air pressure signal according to the rotation angle of the tire, the monitoring device can receive the air pressure signal of a certain strength or more regardless of the rotation angle of the tire. Become. Therefore, the detection device can set the signal strength of the air pressure signal as high as necessary, and the power consumption in the detection device can be suppressed.

(4) The detection device determines a rotation angle range in which the strength of the air pressure signal reaching the monitoring device is increased according to a rotation angle of the tire, and a rotation angle range in which the strength of the air pressure signal is decreased, and A pneumatic signal dead zone angle storage unit that stores information for setting the signal strength of the pneumatic signal, and the signal strength setting unit includes the rotation angle acquired by the rotational angle detection unit and the pneumatic signal dead zone angle storage unit; Based on the stored information, when the rotation angle of the tire belongs to a rotation angle range in which the intensity of the air pressure signal is increased, the signal intensity of the air pressure signal is set to a weak level, and the rotation angle of the tire is In the case of belonging to a rotation angle range in which the strength of the air pressure signal becomes weak, a configuration in which the signal strength of the air pressure signal is set to a high level is preferable.

  In this aspect, when the rotation angle of the tire belongs to a rotation angle range in which the air pressure signal reaching the monitoring device is strong, the detection device transmits the air pressure signal at a weak level. On the contrary, when the rotation angle of the tire belongs to the rotation angle range in which the request signal reaching the monitoring device is weak, the detection device and the air pressure signal are transmitted at a high level. Therefore, the detection device can set the signal strength of the air pressure signal as high as necessary, and the power consumption in the detection device can be suppressed.

(5) The detection device according to this aspect is a detection device that is provided in a vehicle tire and wirelessly transmits a pneumatic signal obtained by detecting the pneumatic pressure of the tire, and a request signal that requests the pneumatic signal. The request signal receiving unit for receiving the rotation angle, the rotation angle detecting unit for detecting the rotation angle of the tire, and the reception sensitivity of the request signal receiving unit are set according to the rotation angle detected by the rotation angle detection unit. A sensitivity setting unit; and a pneumatic signal transmission unit that transmits the pneumatic signal when the request signal is received by the request signal reception unit.

  In this aspect, like the aspect (1), the detection apparatus can set the reception sensitivity of a request signal to high sensitivity as needed, and can suppress power consumption in the detection apparatus.

[Details of the embodiment of the present invention]
A specific example of a tire pressure monitoring system according to an embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

  FIG. 1 is a conceptual diagram showing a configuration example of a tire pressure monitoring system according to an embodiment of the present invention. The tire pressure monitoring system according to the present embodiment includes a monitoring device 1 provided at an appropriate position of the vehicle body, a detection device 2 provided on each of the wheels of a plurality of tires 3 attached to the vehicle C, and a notification device 4. Is provided. In the tire pressure monitoring system of the present embodiment, when the vehicle stops, the monitoring device 1 performs two-way wireless communication with each detection device 2 to acquire the pressure information of each tire 3, and the notification device 4 acquires the acquired pressure information. Notification according to is performed.

  A plurality of LF transmission antennas 14 a corresponding to the respective tires 3 are connected to the monitoring device 1. For example, the four LF transmitting antennas 14a are provided at the right front, right rear, left rear, and left front tire positions of the vehicle C. The tire position is the position of the tire 3 house and its surroundings, and is a position where the detection device 2 provided in each tire 3 can individually receive a signal transmitted from each LF transmitting antenna 14a.

  Note that the LF band and the UHF band are examples of a radio wave band used when performing wireless communication, and are not necessarily limited thereto. The monitoring device 1 is connected to the notification device 4 via a communication line, and the monitoring device 1 transmits the acquired air pressure information to the notification device 4. The notification device 4 receives the air pressure information transmitted from the monitoring device 1 and notifies the air pressure of each tire 3. Further, the notification device 4 issues a warning when the air pressure of the tire 3 is less than a predetermined threshold value.

  FIG. 2 is a block diagram illustrating a configuration example of the monitoring device 1. The monitoring device 1 includes a control unit 11 that controls the operation of each component of the monitoring device 1. A storage unit 12, a pneumatic signal reception unit 13, a request signal transmission unit 14, and a communication unit 15 are connected to the control unit 11.

  The control unit 11 is a microcomputer having, for example, one or a plurality of CPUs (Central Processing Units), a multi-core CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like. The CPU of the control unit 11 is connected to the storage unit 12, the pneumatic signal reception unit 13, the request signal transmission unit 14, and the communication unit 15 via an input / output interface. The control unit 11 controls the operation of each component by executing a control program stored in the storage unit 12 and executes the tire pressure monitoring process according to the present embodiment.

  The storage unit 12 is a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. The storage unit 12 stores a control program for executing tire pressure monitoring processing by the control unit 11 controlling the operation of each component of the monitoring device 1. The storage unit 12 stores an identifier table 12a. Details of the identifier table 12a will be described later.

  An RF receiving antenna 13 a is connected to the air pressure signal receiving unit 13. The air pressure signal receiving unit 13 receives a signal transmitted from the detection device 2 using radio waves in the RF band by the RF receiving antenna 13a. The air pressure signal receiving unit 13 is a circuit that demodulates the received signal and outputs the demodulated signal to the control unit 11. Although a UHF band of 300 MHz to 3 GHz is used as a carrier wave, the carrier wave is not limited to this frequency band.

  The request signal transmission unit 14 is a circuit that modulates the signal output from the control unit 11 into an LF band signal and transmits the modulated signal to the plurality of detection devices 2 from the plurality of LF transmission antennas 14a. Specifically, the request signal transmission unit 14 sequentially transmits a request signal for requesting transmission of a pneumatic signal from each LF transmission antenna 14a in accordance with the control of the control unit 11. As a carrier wave, an LF band of 30 kHz to 300 kHz is used, but it is not limited to this frequency band.

  The communication unit 15 is a communication circuit that performs communication according to a communication protocol such as CAN (Controller Area Network) or LIN (Local Interconnect Network), and is connected to the notification device 4. The communication unit 15 transmits information related to the air pressure of the tire 3 to the notification device 4 under the control of the control unit 11.

  The notification device 4 is, for example, a display unit or a display unit provided in an instrument panel instrument, which is provided with a display unit or a speaker that notifies information related to the air pressure of the tire 3 transmitted from the communication unit 15 by an image or sound. Etc. The display unit is a liquid crystal display, an organic EL display, a head-up display, or the like. For example, the notification device 4 displays the air pressure of each tire 3 provided in the vehicle C with images or characters.

  FIG. 3 is a conceptual diagram showing an example of the identifier table 12a. The identifier table 12a includes a plurality of tire positions, an antenna identifier for identifying the LF transmission antenna 14a disposed in the vicinity of the tire position, and a sensor identifier of the detection device 2 provided in the tire 3 at the tire position. It is stored in association. In the example shown in FIG. 3, the antenna identifiers “1”, “2”, “3”, and “4” are the LF transmission antennas provided at the right front, right rear, left front, and left rear tire positions, respectively. 14a is shown. Also, sensor identifiers “1111”, “2222”, “3333”, and “4444” are associated with the front right, right rear, left rear, and left front tire positions, respectively.

  FIG. 4 is a block diagram illustrating a configuration example of the detection device 2. The detection device 2 includes a sensor control unit 21 that controls the operation of each component of the detection device 2. A sensor storage unit 22, an air pressure signal transmission unit 23, a request signal reception unit 24, an air pressure detection unit 25, a temperature detection unit 26, and a rotation angle detection unit 27 are connected to the sensor control unit 21.

  The sensor control unit 21 is a microcomputer having, for example, one or a plurality of CPUs, a multi-core CPU, a ROM, a RAM, an input / output interface, and the like. The CPU of the sensor control unit 21 is connected to the sensor storage unit 22, the air pressure signal transmission unit 23, the request signal reception unit 24, the air pressure detection unit 25, the temperature detection unit 26, and the rotation angle detection unit 27 via an input / output interface. Yes. The sensor control unit 21 reads a control program stored in the sensor storage unit 22 and controls each unit. The detection device 2 includes a battery (not shown) and operates with electric power from the battery.

  The sensor storage unit 22 is a nonvolatile memory. The sensor storage unit 22 stores a control program for the CPU of the sensor control unit 21 to perform processing related to detection and transmission of the air pressure of the tire 3. The sensor storage unit 22 stores a dead zone table 22a. Details of the dead zone table 22a will be described later. Furthermore, a unique sensor identifier for identifying itself and the other detection device 2 is stored.

  The air pressure detection unit 25 includes, for example, a diaphragm, and detects the air pressure of the tire 3 based on the deformation amount of the diaphragm that changes depending on the magnitude of the pressure. The air pressure detection unit 25 outputs a signal indicating the detected air pressure of the tire 3 to the sensor control unit 21.

  The temperature detection unit 26 includes, for example, an element whose electrical resistance changes with temperature, and detects the temperature of the tire 3 based on the voltage between the elements that changes with temperature change. The temperature detection unit 26 outputs a signal indicating the detected temperature of the tire 3 to the sensor control unit 21.

  The rotation angle detection unit 27 includes a gyro sensor that can detect its own posture, for example. Since the detection device 2 is provided on the wheel of the tire 3, when the tire 3 rotates, the posture of the rotation angle detection unit 27 also changes. The rotation angle detection unit 27 specifies the rotation angle of the tire 3 based on the detection result output from the gyro sensor, and outputs angle information indicating the specified rotation angle to the sensor control unit 21. The angle information is, for example, information that represents the rotation angle of the tire 3 with reference to the rotation angle at which the detection device 2 is located at the highest point.

  An RF transmission antenna 23 a is connected to the air pressure signal transmission unit 23. The air pressure signal transmission unit 23 modulates the air pressure signal generated by the sensor control unit 21 into a UHF band signal, and transmits the modulated air pressure signal using the RF transmission antenna 23a. The air pressure signal transmission unit 23 includes an RF signal strength changing unit 23b that changes the signal level of the air pressure signal to be transmitted. The RF signal strength changing unit 23 b is an amplifier, for example, and changes the signal strength of the pneumatic signal according to the control signal output from the sensor control unit 21.

  The request signal receiving unit 24 is connected to an LF receiving antenna 24a. The request signal receiving unit 24 receives various signals such as a request signal transmitted from the monitoring device 1 using radio waves in the LF band by the LF receiving antenna 24 a and outputs the received signals to the sensor control unit 21. Further, the request signal receiving unit 24 includes an LF signal reception sensitivity changing unit 24b that changes the reception sensitivity of a request signal that is an LF signal. The LF signal reception sensitivity changing unit 24 b is an amplifier, for example, and changes the reception sensitivity of the request signal according to the control signal output from the sensor control unit 21.

  The sensor control unit 21 executes the control program to acquire signals indicating the air pressure and temperature of the tire 3 from the air pressure detection unit 25 and the temperature detection unit 26, and the air pressure information and temperature information based on the signals and the detection device 2 is generated and output to the air pressure signal transmission unit 23.

FIG. 5 is a conceptual diagram showing the LF dead zone, and FIG. 6 is a conceptual diagram showing an example of the dead zone table 22a. Since the detection device 2 is provided on the wheel of the tire 3, when the tire 3 rotates, the positional relationship between the LF transmission antenna 14a and the detection device 2 changes. For this reason, as shown in FIG. 5, there is a rotation angle range in which the intensity of the request signal reaching the detection device 2 becomes weak. The said angle range is an area | region where the detection apparatus 2 cannot receive the request signal transmitted with the weak signal strength from the monitoring apparatus 1, or it becomes difficult to receive. Hereinafter, the region is appropriately referred to as an LF dead zone.
Similarly, there is a rotation angle range in which the intensity of the air pressure signal reaching the monitoring device 1 becomes weak. The angle range is an area where the monitoring device 1 cannot receive the air pressure signal transmitted from the detection device 2 with a weak signal strength, or is difficult to receive. Hereinafter, the region is appropriately referred to as an RF dead zone.

  The dead zone table 22a associates the rotation angle range in which the intensity of the LF signal reaching the detection device 2 becomes weak with the rotation angle range in which the intensity of the RF signal transmitted from the detection device 2 and reaches the monitoring device 1 becomes weak. I remember. The rotation angle range where the intensity of the LF signal becomes weak and the rotation angle range where the RF signal cannot be received are values obtained by measurement in advance. The rotation angle range is expressed with reference to the origin, for example. The position of the origin is not particularly limited. For example, the rotation angle when the detection device 2 is positioned at the highest point may be the origin. Note that the rotation angle range in which the strength of the request signal reaching the detection device 2 is weak and the rotation angle range in which the strength of the air pressure signal reaching the monitoring device 1 is generally different. The dead zone table 22a corresponds to the request signal dead zone angle storage unit and the pneumatic signal dead zone angle storage unit of the above aspect.

  Next, the procedure of the tire pressure monitoring process will be described. Below, the process of the monitoring apparatus 1 and the process of the detection apparatus 2 are demonstrated separately.

  FIG. 7 is a flowchart showing a processing procedure of the monitoring apparatus 1. The control unit 11 of the monitoring device 1 monitors the air pressure of the tire 3 by executing the following process at an arbitrary timing while the vehicle is stopped. For example, the following processing is executed at the timing when an ignition switch (not shown) is turned on from an off state. First, the control unit 11 selects a tire position where the air pressure of the tire 3 has not been detected among the right front, left front, right rear, and left rear (step S11).

  Next, the control unit 11 causes a request signal for requesting an air pressure signal to be transmitted from the LF transmission antenna 14a corresponding to the tire position selected in Step S11 (Step S12). And the control part 11 receives the air pressure signal transmitted from the detection apparatus 2 according to a request signal (step S13), and outputs the air pressure information contained in the received air pressure signal to the alerting | reporting apparatus 4, thereby providing air pressure information. Is notified to the driver (step S14).

  Next, the control unit 11 determines whether or not all the air pressures of the tires 3 have been confirmed (step S15). When it is determined that there is a tire 3 whose air pressure has not been confirmed (step S15: NO), the control unit 11 returns the process to step S11 and executes the same process for the tire 3 whose air pressure has not been detected. When it determines with having confirmed the air pressure of all the tires 3 (step S15: YES), the control part 11 finishes a tire air pressure monitoring process.

  FIG. 8 is a flowchart showing a processing procedure of the detection apparatus 2. The detection device 2 includes an acceleration sensor (not shown). When the rotation stop of the tire 3 is detected, the sensor control unit 21 of the detection device 2 executes the following process. When the rotation of the tire 3 is stopped, the sensor control unit 21 detects the rotation angle of the tire 3 by the rotation angle detection unit 27 and determines whether or not the detection device 2 is in the LF dead zone. (Step S31). Specifically, the sensor control unit 21 reads the rotation angle range of the LF dead zone from the dead zone table 22a, and determines whether or not the rotation angle of the tire 3 belongs to the rotation angle range.

  When it is determined that the detection device 2 is in the LF dead zone (step S31: YES), the sensor control unit 21 outputs a control signal to the LF signal reception sensitivity changing unit 24b and sets the reception sensitivity of the LF signal to high sensitivity. (Step S32) When it is determined that the detection device 2 is not in the LF dead zone (Step S31: NO), the sensor control unit 21 outputs a control signal to the LF signal reception sensitivity changing unit 24b to increase the reception sensitivity of the LF signal. Low sensitivity is set (step S33).

  Then, the sensor control unit 21 transitions to a standby state in which power consumption is reduced (step S34). The detection device 2 in the standby state monitors the request signal without performing air pressure detection and air pressure signal transmission (step S35), and when the request signal is received by the request signal receiving unit 24 (step S35: YES), the sensor control unit 21 is activated (step S36), and the air pressure detection unit 25 and the temperature detection unit 26 detect the air pressure and temperature of the tire 3 (step S37). The request signal is monitored with the reception sensitivity of the LF signal set in step S32 or step S33. If the request signal has not been received (step S35: NO), the request signal is continuously monitored in the standby state.

  And the sensor control part 21 determines whether the detection apparatus 2 exists in RF dead zone (step S38). Specifically, the sensor control unit 21 reads the rotation angle range of the RF dead zone from the dead zone table 22a, and determines whether or not the rotation angle of the tire 3 belongs to the rotation angle range.

  When it is determined that the detection device 2 is in the RF dead zone (step S38: YES), a control signal is output to the RF signal strength changing unit 23b to set the signal strength of the RF signal to a strong level (step S39), and the RF dead zone. If it is determined that it is not present (step S38: NO), the sensor control unit 21 outputs a control signal to the RF signal strength changing unit 23b to set the signal strength of the RF signal to a weak level (step S40).

  And the sensor control part 21 produces | generates the pneumatic pressure signal containing the air pressure information and temperature information which were detected by step S37, the sensor identifier intrinsic | native to its own detection apparatus 2, etc., and RF transmission is carried out about the produced | generated pneumatic signal. Transmission is performed from the antenna 23a to the monitoring device 1 (step S41), and the process is terminated.

In the tire pressure monitoring system configured as described above, the monitoring device 1 and the detection device 2 can perform bidirectional communication without adjusting the rotation angle of the tire 3 when the vehicle is stopped. Power consumption can be reduced.
Specifically, the monitoring device 1 refers to the dead zone table 22a to determine whether or not the detection device 2 of each tire 3 is in a position where the signal intensity of the request signal reaching the detection device 2 is reduced. Can be determined. And the detection apparatus 2 sets the receiving sensitivity of a request signal to high sensitivity, when it exists in the position where the signal strength of a request signal falls. Therefore, even if the rotation angle of the tire 3 is adjusted or the reception sensitivity of the LF signal in the detection device 2 is not always set high, the monitoring device 1 can activate the detection device 2 and execute the air pressure detection process. And power consumption of the detection device 2 can be suppressed.

Further, the detection device 2 can transmit an air pressure signal to the monitoring device 1 with an RF signal intensity corresponding to the rotation angle of the tire 3.
Specifically, the detection device 2 can determine whether or not the detection device 2 is at a position where the signal intensity of the air pressure signal reaching the monitoring device 1 is reduced by referring to the dead zone table 22a. When the air pressure signal is at a position where the air pressure signal decreases, the detection device 2 transmits the air pressure signal at a strong level. Therefore, the monitoring device 1 can receive a high-level air pressure signal transmitted from the detection device 2 without adjusting the rotation angle of the tire 3 when the vehicle is stopped. Further, when the detection device 2 is at a position where the signal strength of the air pressure signal does not decrease, the detection device 2 transmits the air pressure signal at a weak level. Therefore, it is possible to transmit an air pressure signal that can be received by the monitoring device 1 without constantly setting the RF signal intensity in the detection device 2 to a high level, and to suppress power consumption of the detection device 2.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Monitoring apparatus 2 Detection apparatus 3 Tire 4 Notification apparatus 11 Control part 12 Memory | storage part 12a Identifier table 13 Air pressure signal receiving part 13a RF receiving antenna 14 Request signal transmitting part 14a LF transmitting antenna 15 Communication part 21 Sensor control part 22 Sensor storage part 22a dead zone table 23 air pressure signal transmission unit 23a RF transmission antenna 23b RF signal strength change unit 24 request signal reception unit 24a LF reception antenna 24b LF signal reception sensitivity change unit 25 air pressure detection unit 26 temperature detection unit 27 rotation angle detection unit C vehicle

Claims (5)

A detection device that is provided on a tire of a vehicle and wirelessly transmits a pneumatic signal obtained by detecting the pressure of the tire, and receives the pneumatic signal transmitted from the detection device and monitors the pneumatic pressure of the tire A tire pressure monitoring system comprising a monitoring device,
The monitoring device
A request signal transmitter for wirelessly transmitting a request signal for requesting the air pressure signal to the detection device;
The detection device includes:
A request signal receiving unit for receiving the request signal transmitted from the monitoring device;
A rotation angle detector for detecting the rotation angle of the tire;
A sensitivity setting unit for setting the reception sensitivity of the request signal receiving unit according to the rotation angle detected by the rotation angle detecting unit;
A tire pressure monitoring system comprising: a pneumatic signal transmission unit that transmits the pneumatic signal when the request signal is received by the request signal receiving unit. The detection device includes:
The request signal reception sensitivity is set by determining a rotation angle range in which the intensity of the request signal reaching the detection device is increased according to a rotation angle of the tire and a rotation angle range in which the intensity of the request signal is decreased. A request signal dead zone angle storage unit for storing information for
The sensitivity setting unit
Based on the rotation angle detected by the rotation angle detection unit and the information stored in the request signal dead zone angle storage unit, when the rotation angle of the tire belongs to a rotation angle range in which the intensity of the request signal is increased, When the reception sensitivity of the request signal receiving unit is set to low sensitivity and the rotation angle of the tire belongs to a rotation angle range in which the intensity of the request signal is weak, the reception sensitivity of the request signal receiving unit is set to high sensitivity. The tire pressure monitoring system according to claim 1. The detection device includes:
The tire air pressure monitoring system according to claim 1, further comprising a signal intensity setting unit that sets a signal intensity transmitted by the air pressure signal transmission unit according to the rotation angle detected by the rotation angle detection unit. The detection device includes:
The signal strength of the air pressure signal is set by discriminating the rotation angle range in which the strength of the air pressure signal reaching the monitoring device is increased according to the tire rotation angle and the rotation angle range in which the strength of the air pressure signal is weakened. A pneumatic signal dead zone angle storage unit for storing information for
The signal strength setting unit is
Based on the rotation angle acquired by the rotation angle detection unit and the information stored in the air pressure signal dead zone angle storage unit, when the rotation angle of the tire belongs to a rotation angle range in which the intensity of the air pressure signal is increased, The signal strength of the air pressure signal is set to a high level when the signal strength of the air pressure signal is set to a weak level and the tire rotation angle belongs to a rotation angle range in which the strength of the air pressure signal becomes weak. The tire pressure monitoring system described. A detection device that is provided on a tire of a vehicle and wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire,
A request signal receiving unit for receiving a request signal for requesting the air pressure signal;
A rotation angle detector for detecting the rotation angle of the tire;
A sensitivity setting unit for setting the reception sensitivity of the request signal receiving unit according to the rotation angle detected by the rotation angle detecting unit;
An air pressure signal transmitting unit that transmits the air pressure signal when the request signal is received by the request signal receiving unit.

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