JP3354887B2 - Tire pressure warning device transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire pressure alarm device for detecting an abnormality in tire pressure and alerting a driver in a vehicle, and more particularly to a tire pressure alarm device capable of improving the antenna efficiency of a transmitter. It concerns the transmitter.

[0002]

2. Description of the Related Art The present applicant has filed a Japanese Patent Application No. Hei 9-364622.
A tire pressure alarm device which detects that the air pressure of a vehicle tire has decreased by the above-mentioned issue and notifies the driver of the decrease has been filed. FIG. 2 is a longitudinal sectional view showing a transmitter of the conventional tire pressure alarm device. This transmitter is composed of a transmitter 7 arranged inside the wheel rim 1 and a valve stem 17 for injecting air into the tire. It is composed of

The transmitting unit 7 includes a pressure detecting unit 3 for detecting tire pressure in a case 18, a signal processing circuit 4 for transmitting a signal of the detected pressure to a receiver on the vehicle body side by radio waves, A battery 5 for operating the microcomputer is built in. Further, the output of the signal processing circuit 4 is conducted to the valve stem 17 via the power supply line 6. The valve stem 17 has grommets 19, 20,
It is fixed to the wheel rim 1 by a nut 22 via a washer 21.

A coil-shaped antenna 29 comprising a nut 27 and a coil 28 covered with an insulating material is fixed to the male screw 16 of the valve stem by screwing, and the radio wave output of the signal processing circuit 4 is Radiation is emitted from the coiled antenna 29 via the valve stem 17.

[0005]

However, as described above, in the case of the coil-shaped antenna 29 composed of the nut 27 and the coil 24 covered with the insulating material, since the height from the wheel rim is low, the radiation efficiency of the antenna is low. However, the actual radiated electric field when the wheel rim is mounted is weak, and it is necessary to install a receiving antenna near the transmitter, that is, in the vicinity of each tire, in order to enhance the transmission and reception of the system. For this reason, it is structurally very expensive to provide a receiving antenna that can withstand the severe environment around the tire.

In some wheel designs, the valve stem is completely hidden, and in order to prevent a reduction in radiation efficiency in such a case, it is necessary to impose restrictions on the wheel design.

As a countermeasure, a coiled antenna 29
There is a means to increase the height from the wheel rim by moving the to the tip of the valve stem 17, but if it is located at the tip, the jig used to inject air into the tire cannot be used, and as a tire valve This is a problem in terms of functions and productivity.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to the reduction of the efficiency due to the height of the antenna from the wheel as described above, the reduction of the radiation efficiency due to the influence of the wheel design, and the reduction of the actual radiated electric field. At the same time as preventing, it was made to emit radio waves more efficiently, and by providing a coiled antenna in the tire valve cap located at the tip of the valve stem, it efficiently emitted radio waves,
It is an object of the present invention to provide a tire pressure warning device capable of significantly improving transmission performance by minimizing the influence of wheel design.

That is, the present invention relates to a transmitter for a tire pressure alarm device, wherein a tire valve for injecting air into a tire and a transmitter for detecting air pressure in the tire and transmitting the detected air pressure to the vehicle side are integrated. The valve stem 17 of the tire valve and the transmission unit 7 integrated with the valve stem 17
And a metal cap 23 provided with an internal thread on the inner surface and a coil cap valve 30 with a built-in coil formed by insert molding a coil 24 electrically connected to the cap 23 to form a transmitter. A radio wave is emitted from the coil 24 by fixing the valve cap 30 to the tip, and this is a transmitter of the tire pressure alarm device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a transmitter of a tire pressure warning device according to the present invention. The tire pressure warning device of the present invention includes a transmission unit 7 arranged inside the wheel rim 1, a valve stem 17 for injecting air into a tire, and a valve cap 30 with a built-in coil.

The transmission unit 7 includes a pressure detection unit 3 for detecting tire pressure inside a case 18 similarly to the conventional product.
And a signal processing circuit 4 for transmitting a signal from the detected pressure to a receiver on the vehicle body by radio waves, and a battery 5 for operating the microcomputer. The signal processing circuit 4 includes a radio wave output circuit 4a, a valve stem 17,
It has an impedance matching circuit 4b for the coil 24.

The valve stem 17 is provided with a screw 16 on the upper part and a case 18 for accommodating the transmitting part 7 is formed integrally by insert molding on the lower part, and the lower end is formed on the case 18 as in the conventional valve stem. It protrudes downward as if facing inside. An E-ring 26 is fitted to the lower end of the valve stem 17, the power supply line 6 is soldered to the E-ring 26, and one end thereof is connected to the impedance matching circuit 4 b of the signal processing circuit 4. I have. The E-ring 26 may be omitted and the end of the power supply line 6 may be directly soldered to the valve stem 17, for example.

Further, the valve stem 17 of the present invention is inserted into the valve hole from the inside of the wheel rim 1 and is fixed to the wheel rim 1 with nuts 22 via grommets 19 and 20 and washers 21. However, this is also the same as the conventional product.

The difference between the product of the present invention and the conventional product is that a novel valve cap 30 with a built-in coil is used. The valve cap 30 with a built-in coil is made by insert molding. The valve cap 30 is composed of a metal cap 23 provided with an internal thread on the inner surface and a coil 24 covered with an insulating material. The female thread of the cap 30 is screwed into the external thread 16 of the valve stem 17 and fixed, so that the coil 24 and the valve stem 17 are conducted.

[0015]

As described above, in the tire pressure warning device of the present invention, the valve stem 17 is used as a conduction path, and the coil-shaped valve with a built-in antenna is screwed to the external thread 16 at the tip of the valve stem 17. Because the cap is provided, the height of the antenna from the wheel increases,
Radio waves can be efficiently emitted and transmission performance can be significantly improved. The valve cap 30 with a built-in coil
Although this is a new configuration, the metal cap 23 and the coil 24 are added to the conventional valve cap, so that the cost does not increase significantly as compared with the conventional product.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a transmitter of a tire pressure warning device according to the present invention.

FIG. 2 is a longitudinal sectional view of a transmitter of a conventional tire pressure warning device.

[Explanation of symbols]

1 wheel rim 3 pressure detector 4
Signal processing circuit 4a Output circuit 4b Matching circuit 5
Battery 6 Power supply line 7 Transmitter 16
Male thread 17 Valve stem 18 Case 1
9, 20 Grommet 21 Washer 22 Nut 2
3 Metal cap 23 24 Coil 25 Packing 2
6 E-ring 27 Nut 28 Coil 2
9 Coiled antenna 30 Coil built-in valve cap

Claims (1)

(57) [Claims] A tire valve for injecting air into the tire;
Transmission that detects the air pressure in the ear and sends it to the vehicle by radio waves
In the transmitter of the tire pressure warning device with an integrated unit
A valve stem 17 of the tire valve;
The transmitting part 7 integrated with the stem 17 and the internal thread
The metal cap 23 is electrically connected to the cap 23.
Built-in coil formed by insert molding the coil 24
A transmitter is constituted by the valve cap 30 and the valve
Fixing the valve cap 30 to the tip of the bus stem 17
With this, the radio wave is radiated from the coil 24.
A transmitter for a tire pressure warning device, characterized in that: