JP2007008206A - Tire pressure monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly use a wheel speed sensor used in ABS to remove a receiving antenna associated with a tire air pressure sensor on a one-to-one basis, thereby reducing costs and simplifying assembly. Provide tire pressure monitoring system.
An ABS wheel speed sensor 6a detects a rotation speed of a wheel 1a based on a change in magnetic flux accompanying rotation of a magnetic encoder 2a, and transmits a signal of the rotation speed to an ABS control unit 7. Thereby, the ABS control unit 7 realizes an ABS function that makes the slip ratio of each wheel constant. Further, a wireless reception antenna (not shown) built in the wheel speed sensor 6a wirelessly receives a detection signal (that is, a tire pressure signal) from the tire pressure detection sensor 3a, and the tire pressure signal is received by the tire pressure monitoring unit. Send to 8. As a result, the tire pressure monitoring unit 8 realizes the pressure monitoring function of each tire.
[Selection] Figure 1

Description

  The present invention relates to a tire pressure monitoring system that directly detects tire pressure of a vehicle such as an automobile and monitors the tire pressure.

  The tire pressure monitoring system that detects the tire pressure of an automobile detects the tire pressure with a piezoelectric sensor, etc., transmits the detection signal wirelessly to the vehicle body side, and the tire pressure is normal on the ECU (Electric-Control-Unit) side・ Detects the wheel speed of each wheel with a direct tire pressure monitoring system that determines abnormality and a wheel speed sensor, and wirelessly transmits the detection signal to the vehicle body. If the tire diameter decreases, the wheel speed increases. Based on this principle, there is an indirect tire pressure monitoring system in which the ECU side determines whether the tire pressure is normal or abnormal. Of these, the indirect tire pressure monitoring system cannot detect the tire pressure unless the vehicle is running, but the direct tire pressure monitoring system is stopped even when the vehicle is running. But tire pressure can be detected, so it has some convenience.

In such a direct tire pressure monitoring system, a detection signal (that is, a pneumatic signal) from a tire pressure detection sensor (for example, a piezoelectric sensor using a piezo effect) attached to a tire is wirelessly received by a receiving antenna on the vehicle body side. It is configured to receive. For example, a technology is disclosed in which a reception antenna installed in the vicinity of each wheel wirelessly receives a detection signal of a tire air pressure detection sensor (see, for example, Patent Document 1).
Japanese Patent No. 2639856 (see pages 4 to 6 and FIG. 1)

  However, since the tire air pressure detection sensor disclosed in Patent Document 1 is mounted in the tire, it is difficult to supply power, and a small lithium battery is used due to wheel weight balance and unsprung load. A battery is used. For this reason, the output intensity of the wireless transmission means for wirelessly transmitting the air pressure signal must inevitably be weak, and the receiving antenna is installed in the wheel housing near each tire. In addition, since each wireless transmission means needs to transmit with a minimum radio wave intensity, it is necessary to make the layout of the tire pressure detection sensor and the receiving antenna uniform for each tire. As a result, the assembly work of the entire tire pressure monitoring system becomes precise, and as a result, the number of work steps during assembly may increase.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a tire pressure monitoring system that reduces costs and simplifies assembly.

  A tire pressure monitoring system for a vehicle according to a first aspect of the present invention is a wheel-side device including an air pressure sensor that directly detects tire air pressure and a wireless transmission unit that wirelessly transmits a signal of the detected tire air pressure to the vehicle body side, A vehicle body side device that monitors tire air pressure based on a tire air pressure signal transmitted by a wireless transmission means, and is disposed on the vehicle body side in the vicinity of the wheel, and a wheel speed sensor that detects the rotational speed of the wheel. And a radio receiving antenna for receiving the wirelessly transmitted tire pressure signal, and a signal transmitting means for transmitting the received tire pressure signal to the vehicle body side device.

  According to such a configuration, the wireless receiving antenna that receives the air pressure signal detected by the air pressure sensor is built in the wheel speed sensor used for detecting the rotational speed of the wheel. As a result, the air pressure of each tire can be monitored by receiving a radio signal including tire pressure information transmitted from a tire air pressure detection sensor provided in the tire of each wheel and provided with a pressure sensor. Therefore, if a wheel speed sensor is installed, a wireless receiving antenna that receives tire pressure information is also installed on the vehicle body side. Therefore, since the material and the assembly man-hour for comprising a tire pressure monitoring system are reduced, cost reduction and simplification of an assembly can be achieved.

  The invention according to claim 2 is characterized in that, in the above configuration, the wireless transmission means is driven with less power than the signal transmission means. According to this, since the power consumption of the wireless transmission means built in the tire pressure detection sensor is small, the life of the power source (battery) for driving the tire pressure detection sensor is increased, and a small power source can be used.

  Further, the invention according to claim 3 is that, in the above configuration, the wheel speed sensor is a sensor that detects a rotation speed of the wheel in order to realize an ABS (Anti-lock Brake System). Features. In this way, since a wheel speed sensor is inevitably provided in a vehicle to which ABS is applied, a wireless receiving antenna is used by using the ABS wheel speed sensor without providing a new wheel speed sensor. Can be attached. Therefore, a tire pressure monitoring system can be easily constructed even for existing vehicles.

  According to a fourth aspect of the present invention, in the above configuration, the wireless reception antenna receives a wireless signal transmitted from a portable wireless terminal of a keyless entry system. According to this, the wireless receiving antenna provided in the wheel speed sensor can receive a signal from the portable wireless terminal of the keyless entry system in the same frequency band as the air pressure signal from the tire air pressure detection sensor. Since the wheel speed sensor is installed outside the vehicle (that is, in the vicinity of the wheel), the wireless receiving antenna can receive signals from the portable wireless terminal over a wide range. Therefore, the usability of the keyless entry system is further improved.

  Furthermore, by incorporating the radio reception circuit in the ABS wheel speed sensor, an antenna component provided separately from the tire pressure monitoring unit and in the vicinity of the tire air pressure detection sensor becomes unnecessary.

According to the tire pressure monitoring system of the present invention, it is possible to provide a tire pressure monitoring system that reduces costs and simplifies assembly.
If the wireless transmission means that is driven with less power than the signal transmission means is used, the life of the power source that drives the tire pressure detection sensor is increased.

Further, if the wheel speed sensor is a sensor that detects the rotational speed of the wheel in order to realize an anti-lock brake system, the distance between the tire air pressure detection sensor and the wireless reception antenna is shortened, and the tire air pressure detection sensor is more reliably performed. It is possible to receive radio waves from.
Furthermore, according to the configuration in which the wireless reception antenna is used as an antenna for receiving a radio signal transmitted from the portable wireless terminal of the keyless entry system, the vehicle door can be locked from a distance using the portable wireless terminal of the keyless entry system. It can be easily performed.

<< Summary of Invention >>
Hereinafter, a direct tire pressure monitoring system according to a best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described with reference to the drawings. The tire pressure monitoring system of this embodiment incorporates a wireless receiving antenna that wirelessly receives a detection signal of a tire pressure detection sensor in a wheel rotation speed detection sensor (hereinafter referred to as “wheel speed sensor”) used in ABS. It is characterized by letting. In the following description, a direct tire pressure monitoring system that directly detects tire pressure using a sensor is simply referred to as a tire pressure monitoring system.

  That is, the tire pressure monitoring system according to the present embodiment includes a small and long-life battery power source such as a lithium battery, and detects a tire pressure in accordance with the tire temperature, and the tire pressure detection. In a tire pressure monitoring system including a wireless receiving antenna that wirelessly receives a sensor detection signal and a tire pressure monitoring unit that monitors tire pressure based on the detection signal, the wireless receiving antenna is configured as an ABS. It is built in the wheel speed sensor that is an element. This reduces the installation space of the antenna by incorporating the reception antenna installed in the wheel housing near each wheel in a one-to-one correspondence with the tire pressure detection sensor on the wheel side as in the past. did. Conventionally, it is necessary to install a receiving antenna in a place where radio can be received, so there are restrictions on the place of installation and there are restrictions on the degree of freedom of layout. Built-in can solve the layout problem. That is, the wheel speed sensor detects the wheel speed signal for the ABS, and the wireless reception antenna built in the wheel speed sensor wirelessly receives the detection signal of the tire air pressure detection sensor.

<Embodiment>
Hereinafter, the tire pressure monitoring system of this embodiment will be described in detail. FIG. 1 is a configuration diagram of a tire pressure monitoring system according to this embodiment mounted on a vehicle. The tire pressure monitoring system in this embodiment has a configuration in which a part of the ABS function and a direct tire pressure monitoring function are integrated.

  That is, as shown in FIG. 1, in the tire pressure monitoring system of the present embodiment, each wheel 1a, 1b, 1c, 1d has a wheel rotation speed for ABS (hereinafter referred to as “wheel speed”) as a wheel side device. Rotation type magnetic encoders (wheel pulsars) 2a, 2b, 2c, 2d for detecting the tire pressure, and tire air pressure detection sensors 3a, 3b, 3c, 3d for detecting the air pressure of each tire are mounted. Yes. Here, the magnetic encoders 2a, 2b, 2c, and 2d are mounted on a hub bearing, and the tire pressure detection sensors 3a, 3b, 3c, and 3d are mounted on a rim surface 36 (see FIG. 4) of the wheel. It is assumed that the hub bearing is also included in a part of the wheels 1a, 1b, 1c, 1d.

  Also, wheel speed sensors 6a, 6b, 6c, 6d for ABS are respectively installed in the wheel housings 39 (see FIG. 4) in the vicinity of the wheels 1a, 1b, 1c, 1d in the vehicle body 5. These wheel speed sensors 6a, 6b, 6c and 6d include a magnetic detection element (not shown) for detecting a magnetic pulse from each magnetic encoder 2a, 2b, 2c and 2d, and each tire air pressure detection sensor 3a. , 3b, 3c, and 3d, a wireless receiving antenna (not shown) for receiving tire pressure wireless signals (wireless data information) is incorporated. Here, the tire air pressure detection sensors 3a, 3b, 3c and 3d mounted on the rim surface 36 (see FIG. 4) of the wheel include a wireless transmission means 31, a wireless transmission antenna 32, and a piezoelectric element 34 which is a pneumatic sensor. It is driven using a built-in lithium battery 33 (see FIG. 2).

  Furthermore, the vehicle body 5 acquires the wheel speed information from each wheel speed sensor 6a, 6b, 6c, 6d as a vehicle body side device, and makes the slip ratio of each wheel 1a, 1b, 1c, 1d constant. In addition, an ABS control unit 7 for performing ABS control and tire pressure information detected by each tire pressure detection sensor 3a, 3b, 3c, 3d is incorporated in each wheel speed sensor 6a, 6b, 6c, 6d. (Not shown) and the tire pressure monitoring unit 8 for monitoring the tire pressure of each wheel 1a, 1b, 1c, 1d, and the radio built in each wheel speed sensor 6a, 6b, 6c, 6d. And a keyless unit 9 that implements a keyless entry system that locks / releases a vehicle door by a radio signal received by a receiving antenna (not shown). .

  The ABS control performed by the ABS control unit 7 is performed by extracting, for example, the fastest wheel speed from the wheel speeds detected by the wheel speed sensors 6a, 6b, 6c, and 6d, and using this as a simulated vehicle speed. By controlling the slip rate of each wheel 1a, 1b, 1c, 1d to be an ideal slip rate based on the vehicle speed signal, the slip rate of each wheel 1a, 1b, 1c, 1d is made constant and stable braking. Control is performed. Such ABS control is a well-known technique and is not directly related to the present embodiment, so a detailed description thereof will be omitted.

  Each tire air pressure detection sensor 3a, 3b, 3c, 3d mounted on the tire of each wheel 1a, 1b, 1c, 1d includes, for example, a piezoelectric element 34 as an air pressure sensor, and depends on the pressure value of the tire air pressure. The amount of bending of the piezoelectric element 34 changes to change the generated voltage. Information on the change in the generated voltage is wirelessly transmitted at a predetermined timing, and a high-frequency signal corresponding to the generated voltage is received by the wireless reception antennas incorporated in the wheel speed sensors 6a, 6b, 6c, and 6d. Then, by transferring to the tire pressure monitoring unit 8, the tire pressure monitoring unit 8 can monitor the tire pressure of each wheel 1a, 1b, 1c, 1d.

  At this time, each tire air pressure detection sensor 3a, 3b, 3c, 3d is the information that is the basis of the tire position information of each tire, that is, the ID or sensor ID of each tire, the air pressure value of each tire, and the air temperature of each tire. , Etc. are transmitted to the tire pressure monitoring unit 8 via wireless reception antennas built in the wheel speed sensors 6a, 6b, 6c, 6d at a predetermined timing. Thereby, the tire pressure monitoring unit 8 can uniquely determine which tire pressure information is.

  FIG. 2 is a block diagram showing functions of the tire pressure monitoring system shown in FIG. In this figure, in order to simplify the explanation, a detection system for the wheel speed and the tire air pressure in one wheel 1 is depicted. That is, one wheel speed sensor 6 is arranged on the vehicle body side corresponding to the magnetic encoder 2 and the tire air pressure detection sensor 3 provided on one wheel 1. The wheel speed sensor 6 is connected to the ABS control unit 7 through a + B terminal, signal terminals P1 and P2, and a Sig_GND terminal. Further, a wireless data signal (RF_data) received by the wireless receiving antenna 14 is input to the tire pressure monitoring unit 8 and the keyless unit 9 via the wireless IC 16. That is, the wireless IC 16 functions as a signal transmission unit. Further, the wheel speed sensors 6a, 6b, 6c, 6d in FIG. 1 corresponding to the wheel speed sensor 6 in FIG. 2 are connected to the ABS control unit 7, the tire pressure monitoring unit 8, and the keyless unit 9.

  This will be described in more detail. On the wheel side, a rotary magnetic encoder 2 for detecting the wheel speed for ABS and a tire air pressure detection sensor 3 for detecting the tire air pressure are mounted. The rotary magnetic encoder 2 has, for example, a configuration in which a plurality of permanent magnets are alternately arranged with a polarity of N, S, N, S,. Further, on the wheel side, there is a tire pressure detection sensor 3 including a piezoelectric element 34 that directly detects tire pressure, a wireless transmission means 31 that transmits a detected air pressure detection value as a wireless signal, and a wireless transmission antenna 32. It is installed in the tire. On the other hand, on the vehicle body side, a wheel speed sensor 6 for ABS (see FIG. 1) is installed in the wheel housing near the wheel 1, and further, the wheel speed sensor 6 to the ABS control unit 7, the tire pressure monitoring unit 8, And the keyless unit 9.

  The wheel speed sensor 6 detects, as a wheel speed detection system, a magnetic detection element 11 that detects a change in magnetic flux from the magnetic encoder 2 as a change in resistance, a change in resistance of the magnetic detection element 11, and a pulse corresponding to the wheel speed. Are connected, and an output circuit 13 for driving the relay using a pulse output from the detection circuit 12 is connected. In addition, the magnetic detection element 11 includes four magnetoresistive elements S1, S2, S3, and S4 whose resistance values change, which are bridge-connected, and can detect the rotation direction.

  Further, the wheel speed sensor 6 includes a wireless reception antenna 14 that receives a tire pressure wireless signal from the tire pressure detection sensor 3 as a tire pressure detection system, and a coupling circuit that performs impedance matching of the wireless signal received by the wireless reception antenna 14. 15 and a wireless IC 16 that distributes the impedance-matched wireless signal to the tire pressure monitoring unit 8 and the keyless unit 9 is connected.

  Next, the operation of the tire pressure monitoring system shown in FIG. 2 will be described. First, a wheel speed detection system that detects the wheel speed and performs ABS control will be described. The magnetic detection element 11 of the wheel speed sensor 6 changes the balance relationship of the resistance values in the bridge circuit in accordance with changes in the N and S polarities of the magnetic encoder 2 that rotates as the wheel 1 rotates. The resistance change generated by the magnetic detection element 11 is detected as a wheel speed pulse by the detection circuit 12, and the output circuit 13 switches the relay RY. A wheel speed pulse signal is generated by the relay RY and the resistors R1 and R2, and transmitted to the ABS control unit 7 via the signal terminals P1 and P2. Here, one of the wheel speed pulse signals is used depending on the rotation direction of the wheel 1. Since the wheel speed pulse signal is high when the vehicle rotates at high speed, the relay RY is preferably a relay using a semiconductor switch.

  Since the wheel speed pulse signal is transmitted from the wheel speed sensor 6 to the ABS control unit 7 by the operation as described above, the ABS control unit 7 determines the slip ratio of each wheel based on the wheel speed pulse signal of each wheel 1. ABS control is performed so as to be constant. Such ABS control is a well-known technique and is not the main part of the present embodiment, and therefore further explanation is omitted.

  Next, the tire pressure detection function performed by the tire pressure detection sensor 3 will be described. The wireless reception antenna 14 built in the wheel speed sensor 6 receives a tire pressure signal detected by the tire pressure detection sensor 3 and transmitted at a predetermined timing. Here, the distance between the tire pressure detection sensor 3 and the wireless receiving antenna 14 is short, and this distance is the same for the four tires. Therefore, the tire air pressure detection sensor 3 consumes less power, and the life of the lithium battery 33 that drives it is prolonged. Or the influence which it has on wheel balance etc. can be made small by using a smaller battery.

  The tire pressure signal received by the wireless receiving antenna 14 is impedance-matched with the circuit impedance on the output side by the coupling circuit 15 and further transmitted to the tire pressure monitoring unit 8 and the keyless unit 9 by the wireless IC 16. Are transmitted to the corresponding route. Here, the wireless IC 16 recognizes that the received signal is a tire pressure signal, and transmits the tire pressure signal to the tire pressure monitoring unit 8 together with the tire ID. The tire pressure detection system comprising the tire pressure detection sensor 3 and the wheel speed sensor 6 provided on the four wheels performs such an operation to transmit the tire pressure signal of each tire to the tire pressure monitoring unit 8. Therefore, the tire pressure monitoring unit 8 can monitor the tire pressure of the four wheels.

  Next, a keyless entry system will be described. When the wireless reception antenna 14 of the wheel speed sensor 6 receives a vehicle door lock / release signal transmitted from a portable wireless terminal (not shown), the coupling circuit 15 performs impedance matching of the received lock / release signal, and wirelessly The IC 16 recognizes the lock / release signal and transmits this lock / release signal to the keyless unit 9. As a result, the keyless unit 9 locks or releases the vehicle door.

  That is, according to the tire pressure monitoring system shown in FIG. 2, the wireless reception circuit including the wireless reception antenna 14, the coupling circuit 15, and the wireless IC 16 for transmitting the tire pressure signal to the tire pressure monitoring unit 8 is connected to the wheel 1. By incorporating in the ABS wheel speed sensor 6 disposed in the nearby wheel housing, it is possible to reliably receive the radio wave of the tire pressure signal from the tire pressure detection sensor 3 and transfer it to the tire pressure monitoring unit 8. It becomes.

  Further, by incorporating the wireless reception antenna 14 in the ABS wheel speed sensor 6, the reception antenna in the tire pressure monitoring unit 8 which has been conventionally required is not necessary. Alternatively, a receiving antenna that is separate from the tire pressure monitoring unit 8 and is installed in the wheel housing in the vicinity of the wheel 1 becomes unnecessary. That is, by integrating the radio receiving antenna 14 in the wheel speed sensor 6 and integrating it, the antenna layout becomes extremely easy even when an antenna component is provided.

  Further, since the radio receiving antenna 14 built in the wheel speed sensor 6 can receive the tire air pressure signal and the vehicle door lock / release signal by radio waves in the same frequency band, the radio receiving antenna 14 is used as a tire air pressure monitoring system. Can be used together with the receiving antenna of the keyless entry system. In other words, the keyless entry system conventionally has a dedicated receiving antenna installed in the vehicle, but by installing a wireless receiving antenna outside the vehicle (that is, the wireless receiving antenna on the wheel speed sensor 6 in the vicinity of the wheel 1). As a result, the reception range of the lock / release signal of the vehicle door is expanded, and the response range of the keyless unit 9 can be expanded. Furthermore, since a receiving antenna dedicated to the keyless entry system is not required, the cost can be reduced.

  In this way, the wireless receiving antenna that receives the wireless signal from the tire pressure detecting sensor 3 of each wheel 1 is built in the ABS wheel speed sensor, so that the tire pressure signal wirelessly in the direct tire pressure monitoring system. The reception performance is improved and the dedicated antenna for the tire pressure monitoring system is abolished, so that the cost can be reduced. Furthermore, it is possible to reduce costs by expanding the keyless response range of the keyless entry system and eliminating the keyless dedicated antenna.

  Next, a specific structure of the ABS wheel speed sensor, which is a feature of the present embodiment, and a specific configuration example of mounting the ABS wheel speed sensor on a vehicle will be described. FIG. 3 is a structural diagram of an ABS wheel speed sensor applied to the tire pressure monitoring system of the present embodiment, FIG. 3A is an external view, and FIG. 3B is an internal cross-sectional view. FIG. 4 is a specific configuration diagram in which an ABS wheel speed sensor applied to the tire pressure monitoring system of the present embodiment is attached in the vicinity of the wheel 1.

  As shown in FIG. 3B, a coiled wireless reception antenna 14 is wound around the outer periphery of the rear portion of the wheel speed detection unit 61 in the wheel speed sensor 6. Further, a cable connected to the ABS control unit 7 is connected to the rear part of the wheel speed detection unit 61, and the radio reception antenna 14 is wound along the axis of the cable. According to this configuration, the installation space for the radio receiving antenna 14 is reduced.

  The wireless receiving antenna 14 is connected to the wireless IC 16 via a coupling circuit (not shown), and constitutes a detection function of the tire pressure monitoring system. The wheel speed detection unit 61 is connected to a wheel speed sensor circuit 64 to constitute a wheel speed detection function. The wheel speed sensor 6 having a combined function of the tire air pressure detection function and the wheel speed detection function has an external structure as shown in FIG.

  FIG. 4 is a cross-sectional view showing the configuration of the wheel 1 and the vicinity thereof that have realized the ABS function and the tire pressure monitoring function according to the present embodiment, so that the wheel 1 can be rotated by the rotating shaft 38 supported by the bearing 37. It is configured. Further, the wheel 1 is configured to prevent brake lock by the ABS function, but since that portion is out of the main line of the present embodiment, the description thereof is omitted. The wheel speed sensor 6 having the structure as shown in FIG. 3A, which is a feature of the present embodiment, is fixedly attached to a wheel housing 39 in the vicinity of the rotation shaft 38. At this time, the wheel speed detector 61 of the wheel speed sensor 6 is disposed so as to face the magnetic encoder 2 that rotates integrally with the rotating shaft 38. The tire air pressure detection sensor 3 is attached to a rim surface 36 that rotates integrally with the magnetic encoder 2.

  Therefore, when the wheel 1 rotates, the magnetic encoder 2 rotates simultaneously, so that the magnetic flux generated by the permanent magnet of the magnetic encoder 2 changes. The wheel speed detection unit 61 at the tip of the wheel speed sensor 6 detects the change in the magnetic flux as a wheel speed pulse, and the wireless reception antenna 14 (see FIG. 3B) built in the wheel speed sensor 6 is used as a tire. The tire pressure signal is wirelessly received from the tire pressure sensor 3 attached to the rim surface 36 of the tire. Thereby, the ABS function and the tire pressure monitoring function can be realized.

  That is, the tire pressure monitoring system according to the present embodiment includes a sensor unit (piezoelectric element 34) that detects tire pressure and a wireless transmission antenna 32 that transmits a detected air pressure value detected by the sensor unit as a radio signal. A tire pressure detection sensor 3 on the wheel side, a radio reception antenna 14 that is installed on the vehicle body side and receives a radio signal transmitted from the tire pressure detection sensor 3, and an air pressure detection value connected to the radio reception antenna 14 A tire pressure monitoring system having a vehicle body side tire pressure monitoring unit 8 that includes a signal processing unit that determines whether or not the value is appropriate and outputs an output signal for notifying the driver of the determination information. A wheel rotation speed detection sensor (wheel speed sensor) that is disposed on the vehicle body side in the vicinity of the wheel 1 and detects the rotation speed of the wheel 1 The is characterized in that a radio receiving antenna 14).

  Furthermore, the radio receiving antenna 14 provided in the wheel speed sensor 6 can receive a vehicle door lock / door release signal transmitted from a portable radio terminal of the keyless entry system. Here, the door lock / door release signal is a signal indicating whether the door of the vehicle is locked or not. Thereby, the cost reduction of the vehicle provided with these functions can be aimed at. Thereby, the radio reception circuit built in the ABS wheel speed sensor 6 uses the same frequency band for the radio wave transmitted from the tire pressure detection sensor 3 and the radio wave transmitted from the portable wireless terminal of the keyless entry system. Can be received. Furthermore, since the wheel speed sensor 6 is installed around the wheel 1, the wireless reception circuit built in the wheel speed sensor 6 can receive the radio waves of the keyless entry system from a wide range. Therefore, the reception performance of the keyless entry system is improved, and the usability of the opening / closing operation of the vehicle door by the portable wireless terminal is further improved.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications such as the following are possible.
(1) Although the magnetic detection element 11 using a magnetoresistive element is used in the above embodiment, the rotational speed can be detected using a Hall element.
FIG. 5 is a conceptual diagram showing a wheel speed detection method by a wheel speed sensor that detects the rotation of a gear. Teeth 22 are formed at equal pitch intervals on the outer periphery of the rotor 21 that rotates coaxially with the wheel 1. Further, a Hall IC 23 and a magnet 24 for providing a magnetic flux are integrated with a resin mold 25 so as to face the outer peripheral surface of the teeth 22. Further, the hall IC 23 and the magnet 24 are connected to the ECU 27 by a cable 26. The molded Hall IC 23 and magnet 24 are attached to a wheel housing (not shown) in the vicinity of the wheel 1.

  With such a configuration, the rotor 21 rotates with the rotation of the wheel 1, and the teeth 22 cross the opposite position of the Hall IC 23, thereby changing the magnetic resistance and changing the magnetic flux density passing through the Hall IC 23. Specifically, when the outer peripheral surface (convex surface) of the tooth 22 and the Hall IC 23 face each other, the magnetic resistance decreases, and when the concave surface of the tooth 22 faces the Hall IC 23, the magnetic resistance increases. As a result, the Hall IC 23 generates an electromotive force according to the change in magnetic flux density, and a wheel speed pulse proportional to the rotation speed of the wheel 1 is transmitted.

  According to the tire pressure monitoring system according to the present invention, the ABS wheel speed detection function and the tire pressure monitoring function can be integrated to reduce the cost, so that the cost reduction in mass production of mass-produced vehicles equipped with ABS can be achieved. It can be used effectively.

It is a block diagram of the tire pressure monitoring system of the present invention mounted on a vehicle. It is a block diagram of a tire pressure monitoring system. It is the external view and internal sectional drawing of the wheel speed sensor for ABS applied to the tire pressure monitoring system of this invention. It is the specific block diagram which attached the wheel speed sensor for ABS applied to the tire pressure monitoring system of this embodiment to the vicinity of the wheel. It is a conceptual diagram which shows the detection method of the wheel speed by the wheel speed sensor using a magnetic encoder.

Explanation of symbols

1, 1a, 1b, 1c, 1d Wheel 2, 2a, 2b, 2c, 2d Magnetic encoder 3, 3a, 3b, 3c, 3d Tire air pressure detection sensor 5 Car body 6, 6a, 6b, 6c, 6d Wheel speed sensor 7 ABS Control unit 8 Tire pressure monitoring unit 9 Keyless unit 11 Magnetic detection element 12 Detection circuit 13 Output circuit 14 Radio reception antenna 15 Coupling circuit 16 Wireless IC (signal transmission means)
21 Rotor 22 Teeth 23 Hall IC
24 Magnet 25 Mold 26 Cable 27 ECU
31 Wireless transmission means 32 Wireless transmission antenna 33 Lithium battery 34 Piezoelectric element (pneumatic sensor)
36 Rim surface 37 Bearing 38 Rotating shaft 39 Wheel housing 61 Wheel speed detector 64 Wheel speed sensor circuit

P1, P2 signal terminal R1, R2 resistance RY relay

Claims (4)

A wheel-side device including an air pressure sensor that directly detects the tire air pressure, a wireless transmission unit that wirelessly transmits a signal of the detected tire air pressure to the vehicle body side, and a tire based on the tire air pressure signal transmitted by the wireless transmission unit A vehicle tire pressure monitoring system having a vehicle body side device for monitoring air pressure,
A wheel speed sensor that is disposed on the vehicle body side in the vicinity of the wheel and detects the rotational speed of the wheel, a wireless reception antenna that receives the tire pressure signal transmitted wirelessly, and the received tire pressure signal A signal transmission means for transmitting to the vehicle body side device;
A tire pressure monitoring system for vehicles.   The tire pressure monitoring system for a vehicle according to claim 1, wherein the wireless transmission means is driven with less power than the signal transmission means.   3. The tire pressure monitoring system for a vehicle according to claim 1, wherein the wheel speed sensor is a sensor that detects a rotational speed of the wheel in order to realize an anti-lock brake system. .   The tire pressure monitoring system for a vehicle according to any one of claims 1 to 3, wherein the wireless receiving antenna receives a wireless signal transmitted from a portable wireless terminal of a keyless entry system.

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