JP2001119233A - Antenna device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make receiving sensitivity satisfactory and to make noise to be hardly mixed in an antenna device for a vehicle which receives a signal transmitted by radio from a transmitter outside a vehicle body such as a tire sensor device. SOLUTION: This device is provided with a non-opposite part which is formed by folding back an outer conductor 33 of a lower end part of a coaxial cable 16a and which does not face an outer conductor 33 at a lower end part of a core line 31, and an antenna ATN is constructed with the folded outer conductor part as a sleeve balun. Both the lengths of the non-opposite part and the sleeve balun are defined as about 1/4 wavelength of a used radio wave. The cable 16a is provided side by side with a wire 13a for a wheel speed sensor 11a. A clamp 37 is attached at an appropriate position on the sleeve balun, the clamp 37 is fixed to a bracket 24 provided in a shock absorber 23 and is grounded to a car body BD.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for receiving a signal wirelessly transmitted from a transmitter outside a vehicle body, such as a tire sensor device for detecting information on a tire mounted on a wheel and transmitting the information wirelessly. The present invention relates to an antenna device for a vehicle that leads to an electric circuit device provided on the side of the vehicle.

[0002]

2. Description of the Related Art Conventionally, as this type of apparatus, for example, as disclosed in Japanese Patent Application Laid-Open No. 10-309914,
A wire (wire harness) for a wheel speed sensor connected to a wheel speed sensor that picks up the rotation of the wheel and led to an electric circuit device is used as an antenna to detect the air pressure of a tire that is a transmitter provided outside the vehicle body. There is known an apparatus in which information indicating a tire pressure wirelessly transmitted from a tire pressure sensor device is received by the antenna and guided to an electric circuit device.

[0003]

However, in the above-mentioned conventional apparatus, the wiring for the wheel speed sensor originally transmits a pickup signal indicating the wheel speed.
There is a problem that the receiving sensitivity as an antenna is not so good and noise is mixed in a signal transmitted from a transmitter provided outside the vehicle body such as a tire pressure sensor device due to the pickup signal.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to address the above problems, and an object of the present invention is to provide a vehicular antenna apparatus which has good reception sensitivity and is hardly mixed with noise.

In order to achieve the above object, a structural feature of the present invention is a vehicle for receiving a signal wirelessly transmitted from a transmitter outside a vehicle body and guiding the signal to an electric circuit device provided on the vehicle body side. In the antenna device, a coaxial line having one end connected to the electric circuit device and the other end arranged near the wheel is provided in parallel with the wiring for the wheel speed sensor, and is provided outside the other end of the coaxial line. The present invention is characterized in that the conductor is folded to provide a non-facing portion that does not face the outer conductor at the other end of the core wire, and an antenna having the folded outer conductor portion as a sleeve balun is formed at the other end of the coaxial wire. in this case,
The transmitter is provided, for example, in a tire sensor device that is attached to a wheel and detects information on a tire, and a signal wirelessly transmitted from the transmitter represents the detected information. Note that the sleeve balun is formed in a sleeve shape, and means for converting between a coaxial line (unbalanced mode) and an antenna (balanced mode) (Balance and unba
lancetransducer).

According to this, a sleeve balun type dipole antenna utilizing a coaxial line is formed, and this antenna is provided alongside the wiring for the wheel speed sensor, but is independent, so that the transmitter outside the vehicle body (for example, The reception sensitivity of the information wirelessly transmitted from the tire sensor device) is improved, the noise from the wheel speed sensor is less mixed, and the information from the transmitter (for example, the tire sensor device) outside the vehicle body is transmitted to the electric circuit device. Supplied with high accuracy. Further, since the coaxial line is provided alongside the wiring for the wheel speed sensor, the antenna device can be easily assembled near the wheel where there is little empty space.

Another structural feature of the present invention is that the axial length of the non-opposing portion of the core wire and the axial length of the folded outer conductor portion are each set to approximately 4 times the wavelength of the radio wave used. That is, it was set to one-half. This allows
Current hardly flows through the sleeve balun, and the receiving accuracy of the antenna device is further improved.

Another structural feature of the present invention resides in that the folded outer conductor portion is grounded to a vehicle body.
According to this, even if the coaxial line is provided along with the wiring for the wheel speed sensor, it is possible to prevent a change in impedance due to a current flowing through the wiring, and to improve the receiving accuracy of the antenna device.

Another structural feature of the present invention resides in that the ground position of the folded outer conductor portion on the vehicle body is variable. According to this, even if the receiving condition including the mounting state of the antenna device changes, it becomes possible to match the impedance related to the receiving efficiency of the antenna.

Another feature of the present invention lies in that a ferrite core is arranged at an end of the folded outer conductor opposite to the folded position.
As a result, the ferrite core becomes a resistance to the high-frequency signal, so that the high-frequency current generated in the antenna is prevented from flowing out of the sleeve balun, and the radio wave input to the antenna can be guided to the electric circuit device without being damaged.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram showing an entire vehicle system to which the antenna device is applied according to an embodiment of the present invention. FIG. 2 is an exploded perspective view for explaining an assembled state of the antenna device.

In this vehicle system, each wheel WH1 to WH
4 are provided with wheel speed sensors 11a to 11d for detecting wheel speeds (rotation speeds). Wheel speed sensor 1
1a to 11d are electromagnetic pickups respectively facing the teeth of the rotors 12a to 12d rotating integrally with the hub 21 of each of the wheels WH1 to WH4, and output pulse train signals having a cycle inversely proportional to the rotation speed of the wheels WH1 to WH4. The wheel speed sensors 11a to 11d are wheel speed sensors 11a to 1d.
Wirings (wire harnesses) 13a to 13d for 1d are respectively connected to one ends of the wirings, and the other ends of the wirings 13a to 13d are connected to the electric circuit device 14, respectively.
The wirings 13a to 13d supply the pulse train signals from the wheel speed sensors 11a to 11d to the electric circuit device 14. In the present embodiment, the cores shielded by a shield wire are used.

Further, tire sensors 15a to 15d are mounted on the wheels WH1 to WH4. The tire sensor devices 15a to 15d detect information about the tire 22 such as the air pressure and temperature of each tire 22 of the wheels WH1 to WH4 and wirelessly transmit the information, and include a transmitter and an antenna inside. . In addition, a high frequency signal of, for example, 300 MHz to 375 MHz is used as the used radio wave. The radio waves transmitted from the tire sensor devices 15a to 15d are connected to the electric circuit device 14 at one end.
A formed on coaxial lines 16a to 16d connected to
It is to be received by the TN. Coaxial line 16a
16d supplies the received information on each tire 22 to the electric circuit device 14.

The electric circuit device 14 includes a wheel speed sensor 11a.
-11d based on the pulse train signals from
Each wheel speed of WH4 is calculated, and these wheel speeds are used for various controls of an anti-lock brake device, a traction device, a vehicle attitude control device, a rear wheel steering device, an electric power steering device, and the like. In addition, the electric circuit device 1
4 detects an abnormality related to a tire such as a tire pressure based on information about each tire 22 supplied via the coaxial lines 16a to 16d, and notifies the driver of the occurrence of the abnormality when the abnormality is detected, Record the occurrence of

Next, the structure of the coaxial lines 16a to 16d, the structure of the antenna ATN provided on the coaxial lines 16a to 16d, and the method of assembling the coaxial lines 16a to 16d will be described.

As shown in FIG. 4, each of the coaxial wires 16a to 16d has a core 31 made of a conductor, and an insulating part 32 integrally and cylindrically formed of an insulating material such as resin on the outer periphery of the core 31. An outer conductor 33 provided on the outer periphery of the insulating portion 32 and formed into a net-like and cylindrical shape by knitting a thin conductor wire; and an insulating material such as vinyl chloride provided on the outer periphery of the outer conductor 33 to cover the outer periphery. And a coating film 34 formed in a cylindrical shape.

In the formation of the antenna ATN, first, the coating film 34 at the other end of the coaxial lines 16a to 16d has a length L1 (for example, 2) substantially equal to a quarter wavelength of the radio wave used from the other end.
(00 mm to 250 mm) (see FIG. 4A). Next, the portion of the outer conductor 33 exposed by stripping the coating film 34 is folded back and overlapped on the coating film 34 (see FIG. 4B). As a result, the coaxial line 1
At the other end of each of 6a to 16d, a non-facing portion having an axial length L1 that does not face the outer conductor of the core wire 31 and the folded outer conductor 33 are formed of a sleeve balun made of a sleeve balun. An antenna ATN is formed. The length L2 of the sleeve balun in the axial direction is also substantially equal to the length L1 of the non-opposing portion of the core wire 31, that is, substantially equal to a quarter wavelength of the radio wave used.

Next, a method of assembling the coaxial wires 16a to 16d will be described. As shown in FIG. 2, at one end of each of the wires 13a to 13d for the wheel speed sensors 11a to 11d,
Connector 36 detachably connected to electric circuit device 14
, Respectively, and the above-mentioned wheel speed sensors 11a to 11d are respectively attached to the other ends. The electric circuit device 14 is installed at a predetermined position of the vehicle body BD, and
Reference numerals 3a to 13d extend from the electric circuit device 14 to the wheels WH1 to WH4 along the components of the vehicle body BD. The wheel speed sensors 11a to 11d are mounted on a support member (not shown) that is provided on the vehicle body BD side and rotatably supports the hub 21, and faces the rotors 12a to 12d, respectively.

The intermediate portions of the wires 13a to 13d for the wheel speed sensors 11a to 11d are positioned and fixed by screws 25 to an iron bracket 24 provided at an intermediate portion of the shock absorber 23 via an iron clamp 37. ing. The shock absorber 23 has a body BD at its lower end.
And a lower arm or the like (not shown) that rotatably supports the hub 21 and is connected at its upper end to the vehicle body BD. Further, the wirings 13a to 13
d, another clamp 38 is located above the clamp 37.
The clamp 38 is positioned and fixed at a predetermined position on the vehicle body BD. Thus, the wirings 13a to 13d for the wheel speed sensors 11a to 11d are arranged in a narrow space between the vehicle body BD and the wheels WH1 to WH4 and having a movable member.

On the other hand, a connector 39 is also provided at one end of each of the coaxial wires 16a to 16d having an antenna ATN formed at each other end.
The connector 39 is also detachably connected to the electric circuit device 14. Each coaxial line 16a-1
6d is a wiring 13a to the wheel speed sensors 11a to 11d.
13d, each wheel WH1 to WH
At each of the four positions, it is caulked together with the wirings 13a to 13d by the clamp 37, and is positioned and fixed to the bracket 24 provided on the shock absorber 23.
8 together with the wirings 13a to 13d
D is positioned and fixed.

In this case, the iron clamp 37 is located on the outer conductor, that is, the sleeve balun provided by folding back on the outer peripheral surface of the coaxial wires 16a to 16d, and its position can be changed. I have. As a result, as shown in FIG.
And the distance d from the grounding position to the other end can be varied. Wirings 13a to 13d for wheel speed sensors 11a to 11d and a coaxial line 16a
FIG. 3 shows a state in which .about.16d are bundled by clamps 37 and 38.

In the embodiment configured as described above,
A pulse train signal is sent from the wheel speed sensors 11a to 11d to the wiring 1
When supplied to the electric circuit device 14 through 3a to 13d, the electric circuit device 14 calculates each wheel speed of each wheel WH1 to WH4 based on the pulse train signal, and determines the wheel speed. It is used for various controls such as lock brake devices, traction devices, vehicle attitude control devices, rear wheel steering devices, and electric power steering devices. On the other hand, the tire sensor devices 15a to 15d
Tires 22 such as air pressure and temperature of each tire 22 of WH4
When the antenna ATN formed on the coaxial lines 16a to 16d receives the information, the coaxial lines 16a to 16d receive the information, and the coaxial lines 16a to 16d supply a signal representing the information to the electric circuit device 14. I do. Then, the electric circuit device 14 detects an abnormality related to the tire such as a tire air pressure based on the information about each tire 22 supplied via the coaxial lines 16a to 16d. Notify the occurrence and record the occurrence of the abnormality.

In the embodiment constructed and operated as described above, a non-opposing portion of the core wire 31 not facing the outer conductor 33 and the outer conductor 33 are provided at the other end of the coaxial wires 16a to 16d in a folded manner. The folded portion (sleeve balun) constitutes a sleeve balun type dipole antenna using a coaxial line, and this antenna is made independent of the wirings 13a to 13d for the wheel speed sensors 11a to 11d, so that the tire sensor devices 15a to 15d are provided. The reception sensitivity of the information transmitted from the vehicle is improved, the noise from the wheel speed sensors 11a to 11d is less mixed, and the information from the tire sensor devices 15a to 15d is
4 is supplied with high accuracy. Also, the coaxial cables 16a to 16d
To the wirings 13a to 13d for the wheel speed sensors 11a to 11d.
Wheel WH, which has little empty space
The antenna device can be easily assembled near 1 to WH4.

In the above embodiment, the core 31
And a length L2 in the axial direction of the folded portion (sleeve balun) of the outer conductor 33.
Are set to approximately one-fourth of the wavelength of the radio wave used, so that it is difficult for current to flow through the folded portion (sleeve balun), and the reception accuracy of the antenna device is further improved.
Further, since the folded portion (sleeve balun) is grounded to the vehicle body BD by the clamp 37 and the bracket 24, the coaxial lines 16a to 16d are connected to the wheel speed sensors 11a to 11d.
d for wiring 13a to 13d,
A change in impedance due to the current flowing through 13d can be prevented, and the reception accuracy of the antenna device is further improved.

Further, the grounding position of the folded portion (sleeve balun) on the vehicle body BD may be changed by shifting the position of the clamp 37 to make the grounding position of the folded portion (sleeve balun) on the vehicle body BD. it can. According to this, even if the receiving condition including the mounting state of the antenna device changes, it becomes possible to match the impedance related to the receiving efficiency of the antenna.

In addition, the coaxial cables 16a to 16
The antenna ATN formed at the other end of d can be modified as shown in FIG. That is, the annular ferrite core 50 may be mounted on the outer peripheral surface of the folded portion (sleeve balun) of the outer conductor 33 at the end opposite to the folded position. As a result, the ferrite core 50 becomes a resistance to a high-frequency signal, and the antenna A
The high-frequency current generated in the TN is suppressed from flowing out of the folded portion (sleeve balun), and the radio wave input to the antenna ATN can be guided to the electric circuit device 14 without being damaged, and the reception sensitivity of the antenna ATN is reduced. It will be better.

Further, in the above embodiment, only the example in which the antenna device receives a signal wirelessly transmitted from the tire sensor device has been described. However, this antenna device is an antenna device for a keyless entry system and a beacon system. Such as an antenna device for receiving a signal wirelessly transmitted from a transmitter outside a vehicle body. That is, when the antenna device is used for a keyless entry system, a signal that is wirelessly transmitted from a transmitter outside the vehicle body and that represents information input from an input device such as a keyboard used by a user is used in the above-described embodiment. The antenna device according to the embodiment receives the signal, and guides the received signal to an electric circuit device on the vehicle body side. According to this, since the antenna device is disposed outside the vehicle body, the reception efficiency of the transmission signal transmitted from the keyless entry system is improved, and the antenna device is disposed at each wheel WH1 to WH4. The user can send various instructions to the vehicle from any direction of the vehicle. When the antenna device is used for a beacon system, the antenna device receives signals representing position information, traffic information, and the like wirelessly transmitted from a transmitter embedded in a road surface.

Further, as described above, the antenna device may be configured to receive a signal wirelessly transmitted from a transmitter outside the vehicle body such as a keyless entry system or a beacon system in addition to the tire sensor device according to the above-described embodiment. In this case, by changing the used frequency (carrier frequency) variously, it is possible to avoid increasing the number of antenna devices for receiving signals transmitted from various transmitters.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an entire vehicle system to which a vehicle antenna device according to an embodiment of the present invention is applied.

FIG. 2 is an exploded perspective view for explaining an assembled state of the antenna device.

FIG. 3 is a perspective view showing a state where wires for a wheel speed sensor and a coaxial line forming an antenna are bundled.

FIGS. 4A to 4C are cross-sectional views illustrating a configuration of a coaxial line and a method of forming an antenna.

FIG. 5 is a sectional view showing a modification of the antenna.

[Explanation of symbols]

WH1 to WH4: wheels, ATN: antenna, BD: body, 11a to 11d: wheel speed sensors, 12a to 12d:
Rotor, 13a to 13d: wiring (wire harness), 1
4: Electric circuit device, 15a to 15d: Tire sensor device, 16a to 16d: Antenna, 21: Hub, 22: Tire, 23: Shock absorber, 24: Bracket,
31 core wire, 33 outer conductor, 37, 38 clamp,
50 ... ferrite core.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuyuki Sanno 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takayuki Tsuchiya 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 5J046 AB07 MA08

Claims (6)

[Claims] 1. A vehicle antenna device for receiving a signal wirelessly transmitted from a transmitter outside a vehicle body and leading the signal to an electric circuit device provided on the vehicle body side, wherein the vehicle antenna device is provided together with a wire for a wheel speed sensor. One end is connected to the electric circuit device, and the other end is provided with a coaxial line arranged near the wheel, and the outer conductor at the other end of the coaxial line is turned back to form an outer conductor at the other end of the core wire. An antenna device for a vehicle, wherein a non-opposing portion that does not oppose is provided, and an antenna having the folded outer conductor portion as a sleeve balun is formed at the other end of the coaxial line. 2. The vehicle antenna device according to claim 1, wherein the transmitter is provided in a tire sensor device that is mounted on a wheel and detects information about a tire, and the transmitter transmits a wireless signal from the transmitter. The transmitted signal represents the detected information. 3. The vehicle antenna device according to claim 1, wherein an axial length of the non-opposing portion of the core wire and an axial length of the folded outer conductor portion are used. An antenna device for a vehicle, wherein the wavelength is set to approximately one quarter of the wavelength of a radio wave. 4. The vehicle antenna device according to claim 1, wherein the folded outer conductor portion is grounded to a vehicle body. 5. The vehicle antenna device according to claim 4, wherein a grounding position of the folded outer conductor portion on the vehicle body is variable. 6. A vehicle antenna device according to claim 1, wherein a ferrite core is disposed at an end of said folded outer conductor portion opposite to said folded position. Vehicle antenna device.