JP2005335654A - Tire monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire monitoring system capable of identifying a tire position to which each sensor device is mounted with one antenna disposed in an existing vehicle later. <P>SOLUTION: One antenna 50 connected to a monitoring unit 40 via a coaxial cable 40a is disposed on the right side of the windowpane on the front surface of the vehicle 1, and has uniform directivity in the horizontal surface. The sensor device 3 disposed in each tire 2 transmits the same transmission frame 60 a plurality of times with a different interval. The monitoring unit 40 identifies the tire position to which each sensor device is mounted based on the average of receiving strengths per unit time and the number of receivings of the electric wave received via the antenna 50. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tire monitoring system, and more particularly to a tire monitoring system that can identify the position of a tire to which a sensor device provided in each tire is attached by using one antenna provided later on an existing vehicle. .

  Conventionally, inspection of a physical state of a tire such as tire air pressure is an indispensable work for safe driving of a vehicle. However, since it takes time and labor to manually inspect tires, a tire monitoring system that automatically detects the physical state of tires such as air pressure has been developed and started to be used in general vehicles.

  The tire monitoring system generally includes a sensor device that is attached to a tire to detect a physical state of the tire and wirelessly transmits the detection result, and a monitoring unit that receives data transmitted from the sensor device. It is configured. The sensor device is generally provided inside the tire and is often fixed to the rim or embedded in the tire.

  Conventionally, as such a tire monitoring system, each tire of a vehicle is provided with a sensor device and an antenna in each tire house. The tire pressure data transmitted from the sensor device is received by the antenna and connected to these antennas. A monitoring unit that informs the driver of air pressure information of each tire has been proposed (see, for example, Patent Document 1).

  However, when changing the tire position by tire rotation, replacing the tire, etc., if the relationship between the identification number of the sensor device and the tire position is not manually reset to identify the tire position where the sensor device is provided, There was a problem that it was not possible to notify the air pressure information of the correct tire position.

  As a method for solving this problem, the monitoring unit switches the circuits including the antennas provided in each tire house one by one in order within a predetermined time, so that the amplitude of the received signal is larger than a predetermined value. The thing which memorize | stores the identification number of the sensor apparatus contained in the corresponding tire position and signal is proposed (for example, refer patent document 2).

In addition, the monitoring unit outputs an operation signal to one antenna provided in each tire house in every minute time in order, and corresponds to the antenna that has measured the maximum signal strength among the signal strengths received by the operated antenna. One that stores the tire position and the identification number of the sensor device (see, for example, Patent Document 3), and a directional antenna that is set in the direction in which the directivity to each tire is the strongest are provided, and the monitoring unit sequentially There has been proposed an antenna that selects and receives an antenna and specifies a tire position corresponding to an antenna having the maximum reception intensity among all antennas (see, for example, Patent Document 4).
Special table 2003-509260 gazette JP 2003-196777 A JP 2003-118333 A Special table 2003-306017 gazette

  However, in the tire monitoring system of Patent Document 2 or 3, an antenna must be provided for each tire house, and it takes much time and effort to route the coaxial cable connecting the monitoring unit and the antenna. There was a problem of becoming high.

  Further, Patent Document 4 proposes a method in which radio waves from a plurality of sensor devices are received by a single antenna provided on the roof or floor of a vehicle. However, a hole is formed in the roof or floor when the antenna is provided. Since the vehicle needs to be significantly modified, it is assumed that the vehicle is provided with an antenna in advance, and it has been difficult to provide an antenna on an existing vehicle.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to identify a tire position where each sensor device is attached to an existing vehicle with one antenna provided later. It is to provide a tire monitoring system.

  In order to achieve the above object, the present invention has at least one sensor mounted on each tire of a vehicle, and detects a physical quantity inside the tire, and transmits a detection result by the sensor to the outside of the tire by radio waves. In a tire monitoring system, comprising: a plurality of sensor devices; and a monitoring unit that receives radio waves from the plurality of sensor devices and acquires detection results of the sensors for each sensor device. One antenna having uniform directivity in a horizontal plane for receiving radio waves transmitted from the device, the antennas are provided at different positions with respect to the plurality of sensor devices, A tie to which the plurality of sensor devices are attached based on radio field intensity received by the monitoring unit via the antenna. It is characterized in that it comprises means for identifying the location.

  According to the present invention, each sensor device is attached with one antenna without manually setting the tire position of the sensor device by causing a difference in radio field intensity received by the monitoring unit via the antenna. The tire position can be identified. In addition, the sensor device transmits the same information multiple times to increase the probability that the monitoring unit will receive, and the monitoring unit identifies the tire position by identifying based on the average received intensity per unit time and the number of times received. Accuracy can be increased. Furthermore, by attaching an antenna element provided with a transparent film to the window glass, an antenna can be provided later on an existing vehicle without obstructing the field of view or impairing the appearance.

  The object, configuration, characteristics and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

  1 to 13 show an embodiment of the present invention. FIG. 1 is an external perspective view showing a vehicle equipped with a tire monitoring system. FIG. 2 is a horizontal plan view of the tire monitoring system shown in FIG. 1 is a block diagram showing an electrical circuit of the sensor device shown in FIGS. 1 and 2, FIG. 4 is a configuration diagram of a transmission frame transmitted from the sensor device, FIG. 5 is a schematic diagram of antenna installation, and FIG. 6 is shown in FIG. FIG. 7 is a configuration diagram of the power feeding unit shown in FIG. 5, FIG. 8 is a distribution diagram of received intensity in the horizontal plane of the antenna, FIG. 9 is a measurement result of radio field intensity received by the monitoring unit, and FIG. FIG. 11 is a block diagram showing an electrical circuit of the monitoring unit, FIG. 12 is a flowchart showing the operation of the monitoring unit, and FIG. 13 shows the sensor device position identification process shown in FIG. It is a flow chart.

  First, the configuration of the tire monitoring system will be described with reference to FIGS. 1 and 2. In the description here, the front is the front, the rear is the rear, the right is the right, and the left is the left as viewed from the driver's seat (not shown) in FIG.

  The vehicle 1 is, for example, a four-wheel ordinary passenger car, and is provided with a sensor device 3 that detects the state of the tire 2 in each of the four tires 2 in the front, rear, left, and right, and transmits the detection result by radio waves that are frequency-modulated.

  A monitoring unit 40 that includes a controller and a display panel in the vicinity of a driver's seat (not shown), receives radio waves transmitted from the sensor device 3 and displays the detection result on the display panel is installed. Furthermore, the antenna 50 connected to the monitoring unit 40 via the coaxial cable 40a is provided on the right side of the window glass 4 on the front surface of the vehicle 1 and has uniform directivity in the horizontal plane.

  Since the radio wave intensity transmitted from each sensor device 3 is the same, the radio wave intensity received by the monitoring unit 40 via the antenna 50 is less affected by the directivity of the antenna 50 and is determined by the distance to each sensor device 3. . By providing the antenna 50 at a position where the distance from each sensor device 33 is different, it is possible to cause a difference in reception intensity, and the monitoring unit 40 can identify each sensor apparatus 3 based on the reception intensity.

  The antenna 50 is not limited to the right side of the window glass 4 on the front surface of the vehicle 1 as long as the antenna 50 is provided at a position where the distance from each sensor device 3 is different. Similarly, when the antenna 50 having a predetermined directivity in the horizontal plane is used to make a difference in the reception intensity of the radio wave transmitted from each sensor apparatus 3, each sensor apparatus 3 is similarly identified by the reception intensity. Can do.

  Next, the configuration, operation, and transmitted radio wave of the sensor device shown in FIGS. 1 and 2 will be described with reference to FIGS. 3 and 4.

  In FIG. 3, reference numeral 3 denotes a sensor device, which includes an antenna 31, an antenna switch 32, a rectifier circuit 33, a central processing unit 34, a detection unit 35, a transmission unit 36, and a sensor unit 37.

  In this embodiment, the antenna 31 is matched to a communication frequency of 315 MHz.

  The antenna switch 32 is constituted by, for example, an electronic switch or the like, and switches between the connection between the antenna 31 and the rectifier circuit 33 and the detection unit 35 and the connection between the antenna 31 and the transmission unit 36 under the control of the central processing unit 34.

  The rectifier circuit 33 includes diodes 331 and 332, a capacitor 333, and a resistor 334, and forms a known full-wave rectifier circuit. An antenna 31 is connected to the input side of the rectifier circuit 33 via an antenna switch 32. The rectifier circuit 33 rectifies the high frequency current induced in the antenna 31 by the information request signal transmitted from the monitoring unit 40, for example, converts it into a direct current and stores it in the capacitor 333, which is stored in the central processing unit 34, the detection unit 35, And it outputs as a drive power supply of the transmission part 36. FIG. The capacitor 333 performs both functions of smoothing and storage, but a super capacitor or a secondary battery may be provided for temporary storage.

  The central processing unit 34 includes a well-known CPU 341, a digital / analog (hereinafter referred to as D / A) conversion circuit 342, and a storage unit 343. The CPU 341 operates based on a program stored in the semiconductor memory of the storage unit 343. When the power is supplied and driven, the CPU 341 connects the battery 381 of the power supply unit 38 to the sensor unit 37 to drive the sensor unit 37. Then, the sensor detection result is transmitted to the monitoring unit 40 wirelessly. Further, when the received signal includes write target information together with the write command, the CPU 341 rewrites, adds, or deletes information in the storage unit 341 according to the write command.

  The storage unit 343 includes a ROM in which a program for operating the CPU 341 is recorded, and an electrically rewritable nonvolatile semiconductor memory such as an EEPROM (electrically erasable programmable read-only memory). The unique identification information is stored in advance in an area designated as non-rewritable in the storage unit 343 at the time of manufacture.

  The detection unit 35 includes a diode 351 and an A / D converter 352, the anode of the diode 351 is connected to the antenna 31, and the cathode is connected to the CPU 341 of the central processing unit 34 via the A / D converter 352. . As a result, the received signal is converted into digital data by the detector 35 and input to the CPU 341.

  The transmission unit 36 includes an oscillation circuit 361, a modulation circuit 362, and a high frequency amplification circuit 363. The carrier wave oscillated by the oscillation circuit 361 is modulated by the modulation circuit 362 based on the information signal input from the central processing unit 34, This is supplied to the antenna 31 as a response signal via the high frequency amplifier circuit 363 and the antenna switch 32.

  The sensor unit 37 includes first and second sensors 371 and 372, a switch 373 and an A / D conversion circuit 374. As the first and second sensors 371 and 372, sensors that detect the state of the tire 2 and convert it into an electrical signal and output it are used, such as an air pressure sensor, a temperature sensor, a humidity sensor, a vibration sensor, and an acceleration sensor. In the present embodiment, the first sensor 371 is an air pressure sensor that detects the air pressure inside the tire and outputs a voltage corresponding to the air pressure, and the second sensor 372 is a voltage corresponding to the temperature by detecting the temperature inside the tire. A temperature sensor that outputs Note that the number of sensors is not limited to two, and may be added or decreased as necessary.

  The switch 373 is composed of, for example, an electronic switch, and switches between the output of the first sensor 371 and the output of the second sensor 372 under the control of the central processing unit 34 and connects to the input of the A / D conversion circuit 374.

  The A / D conversion circuit 374 converts the input output voltage of the first sensor 371 or the output voltage of the second sensor 372 into a digital value and outputs it to the CPU 341. The detection results of the first and second sensors 371 and 372 are preferably expressed in three or more stages so that normal and abnormal can be discriminated, and in addition, it can be discriminated that a state of caution is required. It is preferable to convert to a value. In this embodiment, an A / D conversion circuit 374 that converts an 8-bit digital value is used.

  Next, a radio wave transmitted as a response signal will be described.

  The sensor device 3 transmits the contents of the transmission frame 60 shown in FIG. 4 by using a frequency-modulated radio wave. One unit of the transmission frame 60 is 96 bits, and includes a 16-bit preamble 61, a 24-bit frame tuning code 62, and a 64-bit data section 63. The monitoring unit 40 that has received the radio wave determines that the radio wave should be received when the preamble and 61 frame tuning code 62 have a predetermined value, and decodes the contents of the data portion 63.

  The data unit 63 uses a plurality of types of information depending on the state of the sensor device 3. For example, the data part 63 of the detection result transmission mode transmitted when the sensor device 3 normally detects the state of the tire 2 is 24 bits as the ID code 63a and the identification number information of the sensor device 30 as 4 bits as the type 63b. Information on the type of data to be transmitted, information on the number of transmissions per unit time in 4 bits as counter 63c, information on tire pressure in 8 bits as pressure 63d, information on tire pressure in 8 bits as temperature 63e, and information in tire temperature in 8 bits as CRC 63f It has known CRC (Cyclic Redundancy Check) error check information.

  In the present embodiment, the sensor device 3 that detects the air pressure and temperature of the tire 2 and transmits the detection result using one frame has been described. However, the tire air pressure and the tire temperature are respectively transmitted using different frames. The sensor device 3 for transmission may be used, or transmission may be performed using a communication method other than the frame.

  Also, frequency-modulated radio waves have the property of canceling the other radio wave when the radio wave intensity is stronger, so the other radio wave receives the predetermined radio wave intensity without affecting the radio wave intensity of the stronger radio wave intensity be able to.

  However, when radio waves from a plurality of sensor devices 3 overlap, the monitoring unit 40 may be able to receive only one radio wave.

  Therefore, in the present embodiment, the sensor device 3 transmits the same transmission frame 60 a plurality of times at different intervals, so that, for example, even when the first transmission overlaps with radio waves from other sensor devices 3, the second and subsequent times. Prevent duplication of radio waves during transmission.

  In order to prevent radio waves from overlapping, different transmission intervals may be set between the sensor devices, and each sensor device 3 may transmit a plurality of times at the same interval. You may transmit only once in order.

  Next, the configuration and installation state of the antenna shown in FIGS. 1 and 2 will be described with reference to FIGS.

  As shown in FIG. 5, the antenna 50 is a λ / 4 monopole antenna including an antenna element 51, a power feeding unit 52, and a copper plate seal 53 provided on the right surface of the window glass 4 on the front surface of the vehicle 1. It is.

  The antenna element 51 shown in FIG. 6 includes a conductor 51a printed on a transparent film 51b (for example, a polyimide film) and a feeding point 51c. The conductor 51a is bent at a right angle, and the total length of the two sides. L1 + L2 is set to a length of 1/4 of the effective wavelength corresponding to the frequency of the radio wave transmitted from the sensor device 3. The feeding point 51c is a metal piece having a size of L3 × L4, and is attached to the window glass 4 by connecting to the feeding terminal 523 shown in FIG.

  The antenna 50 is not limited to a monopole antenna, and the film 51b does not need to be transparent, for example, when provided at a position other than the window glass 4 of the vehicle 1 or when provided on a motorcycle.

  In this embodiment, the frequency of the transmission radio wave of the sensor device 3 is set to L1 = 80 mm, L2 = 75 mm, L3 = 5 mm, and L4 = 5 mm as an example with respect to 315 MHz. The dimension of the film 51b does not matter.

  The power supply unit 52 includes an installation unit 521 and a connection unit 522, and a power supply terminal 523 is provided on the surface of the installation unit 521 that is attached to the window glass 4. The connection unit 522 has a high-pass filter and a negative feedback amplifier, which will be described later, and is connected to the monitoring unit 40 via a coaxial cable 40a.

  In addition, the power feeding part 52 is also attached to the window glass 4 and fixed with a copper plate seal 53 from above the connection part 522, and one end of the copper plate seal 53 is grounded with the metal of the window frame portion 4a as the ground. Thereby, the shield wire of the coaxial cable 40a is conductively connected to the metal of the window frame portion 4a.

  Since the antenna 50 in this embodiment functions as the antenna 50 of the tire monitoring system by connecting to the coaxial cable 40a, the antenna 50 can be provided only by being attached to a position where one coaxial cable 40a can be routed. .

  Further, since one side of the antenna element 51 is pasted so as to extend in the vertical direction of the window glass 4, the reception intensity in the horizontal plane shown in FIG. 8 becomes substantially uniform regardless of the angle in the horizontal plane. Here, it is considered that the increase in reception intensity at 0 to 90 [deg] as compared with other angles is because the antenna 50 is provided on the right side of the front window glass 4 of the vehicle 1.

  Further, by using the transparent film 51b constituting the antenna element 51, the field of view is not obstructed even when the film is attached to the window glass 4 of the vehicle 1, and the appearance of the vehicle 1 is not impaired.

  Next, an actual measurement result of the radio field intensity received by the monitoring unit via the antenna shown in FIGS. 5 to 8 will be described with reference to FIGS. 9 and 10.

  FIG. 9 is an actual measurement result of the radio field intensity received by the monitoring unit 40 when each tire 2 makes one rotation of the radio wave transmitted by the sensor devices 3 provided on the four tires 2 in the front, rear, left, and right. The reception intensity of radio waves from the sensor device 3 provided on the left front tire 2 is approximately −80 [dBm], the reception intensity of radio waves from the sensor device 3 provided on the left rear tire 2 is approximately −82 [dBm], and right The reception intensity of radio waves from the sensor device 3 provided on the rear tire 2 is approximately −90 [dBm], and the reception intensity of radio waves from the sensor device 3 provided on the right front tire 2 is approximately −95 [dBm]. Here, the decrease in the reception intensity at a predetermined angle in the radio wave from the sensor device 3 provided in each tire 2 is because the sensor device 3 has moved to a position where the antenna 50 is difficult to receive due to the rotation of the tire 2. it is conceivable that.

  Since the reception intensity of the radio waves from the sensor devices 3 provided in the respective tires 2 is different and each has a constant value, the monitoring unit 40 identifies the tire position where each sensor device 3 is attached based on the reception intensity. can do. Therefore, even in the case of rotation of the tire 2 or replacement of the sensor device 3, the monitoring unit 40 can identify from which tire position the sensor device 3 is transmitting based on the received radio wave intensity.

  FIG. 10 is an actual measurement result diagram of the number of times that the monitoring unit 40 receives the radio wave transmitted from the sensor device 3 provided in each tire 2 per unit time via the antenna 50 and the average value of the received intensity. The monitoring unit 40 receives 297 times with respect to 303 transmissions from the sensor device 3 provided on the left front tire 2, has a reception probability of 98.0%, and an average received intensity (this received intensity is different from the received intensity). Dimension and unitless, the same applies hereinafter) is 127.37, and the reception probability is 97.3% with respect to 300 times of transmission from the sensor device 3 provided in the left rear tire 2 and 292 times. The reception intensity average value is 126.48, the reception probability is 93.1% with respect to 303 transmissions from the sensor device 3 provided in the right rear tire 2, the reception probability is 93.1%, and the reception intensity average value is 117.48. 33, the reception probability is 77.8% and the reception intensity average value is 114.56 with respect to the transmission frequency of 325 times from the sensor device 3 provided on the right front tire 2.

  The reception probability of the radio wave from each sensor device 3 is not equal to the case where the radio wave of the other sensor device 3 described above is overlapped. It has declined because it cannot be recognized.

  The sensor device 3 transmits the same transmission frame 60 a plurality of times. For example, even when the monitoring unit 40 cannot receive the first transmission, the reception intensity becomes larger than a predetermined value in the second and subsequent transmissions. Can be received.

  In the figure, the reception probability and the average reception intensity at each tire position decrease in the order of the left front tire, the left rear tire, the right rear tire, and the right front tire, and there are differences in the reception intensity and the number of receptions depending on the tire position. It is shown that. In addition, there is a correlation between the reception probability and the reception intensity average value, and the difference in the reception probability between the tire positions is more significant than the difference in the reception intensity average value, so the tire position is identified by the reception probability. You can also.

  In the present embodiment, the measurement accuracy is leveled by identifying based on the received intensity average value per unit time, but any other value can be identified as long as it is an attribute value of received intensity. Similarly, the reception probability per time can be identified by other attribute values of the number of receptions per unit time.

  Next, the configuration and operation of the monitoring unit shown in FIGS. 1 and 2 will be described with reference to FIGS.

  As shown in FIG. 11, the monitoring unit 40 includes a receiving unit 41, a demodulating unit 42, a central processing unit 43, and a display unit 44. Driving power is supplied to the monitoring unit 40 from the battery of the vehicle 1 or the like.

  The antenna 50 includes the above-described antenna element 51 and a power feeding unit 52, and the power feeding unit 52 includes a known high-pass filter 52a and a negative feedback amplifier 52b. The signal received by the antenna element 51 passes through the high-pass filter 52 a and is sent to the monitoring unit 40 via the negative feedback amplifier 53.

  The receiving unit 41 includes a filter 411 and a receiving IC 412, and the input side of the filter 411 is connected to the antenna 50, receives a radio wave transmitted from the sensor device 3, passes through the filter 411, and then demodulates via the receiving IC 412. 42. The receiving IC 412 measures and digitizes the received radio wave intensity, and sends the digitized radio wave intensity information to the demodulator 42 together with the received signal.

  The demodulation unit 42 includes an A / D conversion circuit 421 and a reception CPU 422. A signal sent from the receiving unit 41 is received as a transmission frame 60 by the reception CPU 422 via the A / D conversion circuit 421. The program of the reception CPU 422 is set so that the data unit 63 is decoded when the radio wave transmitted from the sensor device 3 is received. In the present embodiment, the transmission frame 60 is provided with the above-described preamble 61 and the frame tuning code 62 indicating that the radio wave is from the sensor device 3, so that it can be distinguished from other radio waves.

  The central processing unit 43 includes a main CPU 431 and a memory 432, and controls the display unit 44 by using the data unit 63 and the information on the radio wave intensity from the reception CPU 422 as inputs. The memory 432 includes a ROM in which a program for operating the main CPU 431 is recorded and an electrically rewritable non-volatile semiconductor memory such as an EEPROM, for example, and the received intensity average value per unit time at each tire position described above. And the reception probability is stored in advance in an area designated to be rewritable.

  The display unit 44 displays information of each sensor device 3 on the display panel 441 based on control from the main CPU 431, and outputs sound from the speaker 442.

  Next, the operation of the monitoring unit 40 configured as described above will be described.

  In FIG. 12, the monitoring unit 40 performs sensor device position identification processing when the tire monitoring system is activated (S1). In the sensor device position identification processing S1 shown in FIG. 13, first, the timer of the monitoring unit 40 is reset and timer timing is started (S11). It is determined whether or not the radio wave from each sensor device 3 has been received (S12), and the radio wave intensity received by the receiving IC 412 is measured (S13).

  The reception CPU 422 determines whether or not the received radio wave is a radio wave from each sensor device 3 (1S4). When the reception CPU 422 determines that the radio wave is from the sensor device 3, the main CPU 431 determines the ID code 63a of the received transmission frame 60. The number of receptions is increased by 1, and the data part 63 and the reception intensity are stored in the memory 432 (S15). The monitoring unit 40 repeats S12 to S15 until the predetermined time T1 has elapsed (S16).

  When the time T1 has elapsed, the average value of the reception strength is obtained from the reception strength stored for each ID code 63a, and the reception probability is calculated from the counter 63c and the counted number of receptions (S17). The calculation result of each ID code 63a and the actual measurement result of each tire position stored in the memory 432 in advance are compared to identify the tire position of the sensor device 3 specified by the ID code 63a (S18), and the ID code 63a and The correspondence relationship between the tire positions is stored in the memory 432 (S19).

  After receiving the radio wave from each sensor device 3 after the sensor device position identification process S1 (S2, S3), the tire position is identified by the ID code 63a based on the correspondence (S4), Based on the information, numerical values of air pressure and temperature of each tire 2 are displayed on the display panel 441, and sound is output from the speaker 442 in a predetermined case (S5).

  In the present embodiment, the sensor device position identification process S1 is performed when the tire monitoring system is activated. However, the tire position of each sensor device may be arbitrarily identified. In addition, the actual measurement result of each tire position is not limited to storing in advance, and the actual measurement result may be stored later.

  As described above, according to the tire monitoring system of the present embodiment, by providing the antenna 50 having a uniform directivity in a horizontal plane at a position where the distance from each sensor device 3 is different, a difference is generated in the reception intensity. Each sensor device 3 transmits radio waves at different intervals to prevent a plurality of radio waves from overlapping, and each sensor device 3 can be configured with one antenna 50 without manually setting the tire position of the sensor device 3. The attached tire position can be identified.

  In addition, the probability that the monitoring unit 40 receives the sensor device 3 by transmitting the same transmission frame 60 a plurality of times increases, and the monitoring unit 40 identifies based on the average reception intensity and the number of receptions per unit time, The identification accuracy of the tire position can be increased.

  Further, the antenna 50 can be provided on the existing vehicle 1 later by being attached to the window glass 4, and the field of view can be blocked by using the antenna element 51 provided with the transparent film 51b. The antenna 50 can be provided without deteriorating the appearance.

  The configuration of the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention.

1 is an external perspective view showing a vehicle equipped with a tire monitoring system according to an embodiment of the present invention. Horizontal view of the tire monitoring system shown in FIG. Block diagram showing an electric circuit of the sensor device shown in FIG. 1 and FIG. Transmission frame configuration diagram transmitted from the sensor device in an embodiment of the present invention Schematic of antenna installation in one embodiment of the present invention Configuration of antenna element shown in FIG. FIG. 5 is a configuration diagram of the power feeding unit shown in FIG. Reception intensity distribution diagram in the horizontal plane of the antenna in one embodiment of the present invention FIG. 5 is a diagram showing the actual measurement results of radio field intensity received by the monitoring unit according to the embodiment of the present invention. Transmission / reception measurement result table of sensor device and monitoring unit in one embodiment of the present invention The block diagram which shows the electric circuit of the monitoring unit in one Embodiment of this invention The flowchart which shows operation | movement of the monitoring unit in one Embodiment of this invention. The flowchart which shows the sensor apparatus position identification process shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Tire, 3 ... Sensor apparatus, 4 ... Window glass, 4a ... Window frame part, 31 ... Antenna, 32 ... Antenna switch, 33 ... Rectifier circuit, 331 ... Diode, 332 ... Diode, 333 ... Capacitor 334: Resistor, 34: Central processing unit, 341 ... CPU, 342 ... D / A conversion circuit, 343 ... Storage unit, 35 ... Detection unit, 351 ... Diode, 352 ... A / D converter, 36 ... Transmission unit 361: Oscillator circuit 362 Modulator circuit 363 High frequency amplifier circuit 37 Sensor unit 371 First sensor 372 Second sensor 373 Switch 374 A / D converter circuit 40 Monitoring Unit: 40a ... Coaxial cable, 41 ... Receiver, 411 ... Filter, 412 ... Receiver IC, 42 ... Demodulator, 421 ... A / D converter circuit, 422 ... Receiver CPU, 43 ... Central processor 431 ... Main CPU, 432 ... Memory, 44 ... Display unit, 441 ... Display panel, 442 ... Speaker, 50 ... Antenna, 51 ... Antenna element, 51a ... Conductor, 51b ... Film, 51c ... Feed point, 52 ... Feed unit 52a ... High-pass filter, 52b ... Negative feedback amplifier, 521 ... Installation part, 522 ... Connection part, 523 ... Feed terminal, 53 ... Copper plate seal, 60 ... Transmission frame, 61 ... Preamble, 62 ... Frame tuning code, 63 ... Data portion, 63a ... ID code, 63b ... Type, 63c ... Counter, 63d ... Pressure, 63e temperature, 63f ... CRC, S1 ... Sensor device position identification processing.

Claims (18)

A plurality of sensor devices that are attached to each of all tires of a vehicle, have a sensor that detects a physical quantity inside the tire, and transmits a detection result by the sensor to the outside of the tire by radio waves, and the plurality of sensor devices In a tire monitoring system comprising a monitoring unit that receives radio waves from and acquires the detection results of the sensors for each sensor device,
One antenna connected to the monitoring unit and having uniform directivity in a horizontal plane for receiving radio waves transmitted from the sensor device,
The antenna is provided at a position where distances from the plurality of sensor devices are different from each other,
A tire monitoring system comprising: means for identifying positions of tires to which the plurality of sensor devices are attached based on radio field intensity received by the monitoring unit via the antenna. The sensor device has means for transmitting the same detection result a plurality of times when transmitting the detection result,
The monitoring unit has means for identifying positions of tires to which the plurality of sensor devices are attached based on an average of radio wave intensities of a plurality of detection results received via the antenna. Item 2. The tire monitoring system according to Item 1. The sensor device includes:
The tire monitoring system according to claim 2, further comprising means for transmitting the same detection result at different intervals when transmitting the same detection result a plurality of times. The sensor device includes:
The tire monitoring system according to claim 2 or 3, further comprising means for transmitting the same detection result at a different interval from a transmission interval in the plurality of other sensor devices when transmitting the same detection result a plurality of times. The monitoring unit is
The tire monitoring system according to any one of claims 1 to 4, further comprising means for identifying a position of a tire to which the plurality of sensor devices are attached based on the number of receptions per unit time. The monitoring unit is
The tire monitoring system according to any one of claims 1 to 5, further comprising means for identifying a position of a tire to which the plurality of sensor devices are attached based on an average of the radio field intensity per unit time and the number of receptions. . The tire monitoring system according to claim 1, wherein the antenna is attached to a window glass of the vehicle. The monitoring unit is
The tire monitoring system according to claim 1, wherein a frequency-modulated radio wave transmitted by the sensor device is received via the antenna. The tire monitoring system according to claim 1, wherein the detection result includes at least one of air pressure, temperature, humidity, vibration, and acceleration. A plurality of sensor devices that are attached to each of all tires of a vehicle, have a sensor that detects a physical quantity inside the tire, and transmits a detection result by the sensor to the outside of the tire by radio waves, and the plurality of sensor devices In a tire monitoring system comprising a monitoring unit that receives radio waves from and acquires the detection results of the sensors for each sensor device,
One fixed antenna connected to the monitoring unit and having a predetermined directivity in a horizontal plane for receiving radio waves transmitted from the sensor device;
The antenna is provided such that the radio wave intensity received from the plurality of sensor devices is different,
A tire monitoring system comprising: means for identifying positions of tires to which the plurality of sensor devices are attached based on radio field intensity received by the monitoring unit via the antenna. The sensor device has means for transmitting the same detection result a plurality of times when transmitting the detection result,
The said monitoring unit has a means to identify the position of the tire to which the said several sensor apparatus is attached based on the average of the electromagnetic wave intensity of the detection result of the multiple times received via the said antenna. The tire monitoring system according to claim 10. The sensor device includes:
The tire monitoring system according to claim 11, further comprising means for transmitting the same detection result at different intervals when transmitting the same detection result a plurality of times. The sensor device includes:
The tire monitoring system according to claim 11 or 12, further comprising means for transmitting the same detection result at a different interval from a transmission interval in the plurality of other sensor devices when transmitting the same detection result a plurality of times. The monitoring unit is
The tire monitoring system according to any one of claims 10 to 13, further comprising means for identifying positions of tires to which the plurality of sensor devices are attached based on the number of receptions per unit time. The monitoring unit is
The tire monitoring system according to any one of claims 10 to 14, further comprising means for identifying a position of a tire to which the plurality of sensor devices are attached based on an average of radio field intensity per unit time and the number of receptions. The tire monitoring system according to any one of claims 10 to 15, wherein the antenna is attached to a window glass of the vehicle. The monitoring unit is
The tire monitoring system according to claim 10, wherein a frequency-modulated radio wave transmitted by the sensor device is received via the antenna. The tire monitoring system according to any one of claims 10 to 17, wherein the detection result includes at least one of air pressure, temperature, humidity, vibration, and acceleration.

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