JP3359565B2 - Tire pressure warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless tire pressure alarm device which can confirm the suitability of the tire pressure for a vehicle in a passenger compartment.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 3 and 4, a tire-side pressure detector 18 is installed inside a tire.
There has been proposed a device that includes a power source using a battery 19 and a wireless transmitter 20, transmits a signal by operating a tire pressure switch 21, receives the signal by an antenna on the vehicle body side, and issues an alarm.

[0003]

However, since radio waves are greatly affected by metal objects, the transmission performance of the antenna on the vehicle body side is significantly reduced depending on the installation location, and the radio waves cannot be received stably. , There was a problem that it could not be received at all.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made in order to obtain a higher electric field strength and to stabilize a reception state, and to avoid the influence of a metal body. The receiver antenna is installed on the wheel cap close to the vehicle, connected to the receiver in the vehicle cabin via the wheel rim to which the wheel cap is fixed and the axle to which the wheel rim is fixed, and a display or An alarm is provided to warn of a decrease in air pressure.

[0005]

SUMMARY OF THE INVENTION A tire pressure warning device according to the present invention comprises: a pressure detecting element 1 for detecting tire pressure; a radio transmitter 2 for transmitting information of the pressure detecting element 1; to a transmitting antenna 4, the transmitter 3 which is fixed to the wheel rim 5, a receiving antenna 7 provided in hubcap 6 as the body side of the antenna, the antenna
Through the conductive wheel rim 8 and the axle 9
And a receiver 10 electrically connected to the vehicle interior.
And a display 1 based on the reception information obtained by the receiver 10.
1 and an alarm 12 to warn of a decrease in air pressure.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a tire pressure alarm device according to the present invention on the tire side, in which a pressure sensor 1 for detecting tire pressure, a radio transmitter 2 for transmitting information of the pressure detector 1, and the radio transmitter The transmitter 3 including the two transmitting antennas 4 is fixed to the base of the tire valve 13 in the wheel rim portion 5. The tire valve 13 is fixed to the wheel rim 5 with screws 14 provided at its ends, and a receiving antenna 7 is provided on the wheel cap 6. The receiving antenna 7 is electrically connected to the wheel rim 8. Are linked together. The wheel rim 8 is fixed to the axle 9 with a hub nut 15.

FIG. 2A shows a block diagram of the tire pressure warning device on the tire side. A transmitter 3 includes a pressure detecting element 1 for detecting tire pressure and a radio wave for transmitting information of the pressure detecting element 1. The transmitter 3 includes a transmitter 2 and a transmitting antenna 4 of the radio transmitter 2, and the transmitter 3 is fixed to a wheel rim portion 5.

FIG. 2B shows a block diagram of the tire pressure warning device on the vehicle body side, in which a receiving antenna 7 is provided on a wheel cap 6, a wheel rim 8 of a conductor and an axle 9.
To the receiver 10 in the vehicle cabin electrically connected via
The display 11 and the alarm 12 can warn of a decrease in air pressure based on the reception information obtained by the receiver 10.

[0009]

The operation of the tire pressure alarm device will be described with reference to FIG. 2. As for the transmitter 3 on the tire side, the detected value of the pressure detecting element 1 is signal-processed by a microcomputer or the like, and the pressure data is wirelessly transmitted. To be sent.

On the other hand, the signal received by the receiving antenna 7 installed on the wheel cap is input to the selection switch 16 of the receiver 10 in the vehicle body via the wheel rim 8 and the axle 9. The selection switch 16 is switched to the one with the higher reception intensity, and selects any signal from a total of four antennas in front, back, left and right.

The control device 17 controls the selection switch 16, processes received signals, and displays a pressure value on a display device based on data obtained from the process, and can generate and display an alarm with an alarm device. Is configured and programmed.

In general, the attenuation of the electric field intensity due to radio waves in its free space is theoretically calculated and clarified. However, as in the present invention, in a space around a metal body called a car, radio waves are a continuous connection of electric and magnetic fields, but are attenuated by reflection, absorption, and diffraction due to the presence of metal. Then, the distribution is greatly disturbed.

In the measurement example of the electric field strength when the receiving antenna is placed in the vehicle cabin, the electric field strength in the free space of the transmitter installed in the tire is set to 3 m, which is the legally regulated weak radio output strength. Although it was 54 dbμV / m at the point, it was greatly attenuated. Actually, the attenuation and the degree of the fluctuation were 2 to 20 dbμV / m. Was difficult and practical. For this measure, a complicated system of a receiving system and an antenna system is required, which makes the tire pressure warning device using weak radio for consumer use unrealistic in terms of cost. .

[0014]

As described above, the pneumatic pressure warning device of the present invention enables a large receiving antenna to be installed very close to the transmitter in order to stabilize the receiving state and to avoid the influence of metal objects. For this purpose, a receiving antenna is provided on the wheel cap, and it is connected to a receiver in the cabin through a wheel rim to which the wheel cap is fixed and an axle to which the wheel rim is fixed, and a display or alarm is used based on the received information. This is to warn of a decrease in air pressure.

According to experiments, when the distance of the antenna is 5 cm away from the metal body, the electric field strength is 5 to 10 dbμV.
/ M increase was confirmed. In recent years, most wheel caps are made of resin, and it has been possible to secure an electric field strength of at least 10 dbμV / m or more. Further, the antenna only needs to be a wire having a certain length, and it is extremely easy to install the antenna on the wheel cap, the cost is small, and its practical value is extremely large.

[Detailed description of drawings]

FIG. 1 is a tire side configuration diagram of a tire pressure alarm device according to the present invention.

FIG. 2 shows a block diagram of a tire pressure warning device according to the present invention, wherein FIG.
(B) is a block diagram of the vehicle body side.

FIG. 3 is a configuration diagram of a conventional tire pressure warning device.

FIG. 4 is an enlarged vertical sectional view of a conventional pressure detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Test element 2 Radio wave transmitter 3 Transmitter 4 Transmitting antenna 5 Wheel rim part 6 Wheel cap 7 Receiving antenna 8 Wheel rim 9 Axle 10 Receiver 11 Indicator 12 Alarm 13 Tire valve 14 Screw 15 Hub nut 16 Selection switch 17 Control Device 18 Conventional pressure detector 19 Battery 20 Wireless transmitter 21 Tire pressure switch

Claims (1)

(57) [Claims] 1. A wheel rim section 5 comprising a pressure detecting element 1 for detecting tire pressure, a radio transmitter 2 for transmitting information of the pressure detecting element 1, and a transmitting antenna 4 of the radio transmitter 2. a transmitter 3 which is fixed to a receiving antenna 7 provided in hubcap 6 as the body side of the antenna, the en
Via the conductive wheel rim 8 and the axle 9
And a receiver 10 in the cabin electrically connected to the vehicle
It is, received information obtained display 11 and based on the above receiver 10, the tire pressure warning system that is characterized by alerting the decrease of the air pressure by the warning device 12.