JPH05139128A - Tire air pressure alarm - Google Patents

Abstract

PURPOSE:To prevent any air leakage caused by defective screwing as well as to eliminate demounting and mounting operation performed for each air pressure adjustment, by mounting a signal purpose air valve for a pressure sensor with its center of gravity being kept low so as to reduce its vibration amplitude. CONSTITUTION:A pressure sensor is mounted to a single purpose air valve 6 provided to a tire rim. In this case, the mounting end of this single purpose air valve 6 to the tire rim is arranged according to ETRTO standard, the entire length L of the single purpose air valve 6 is 28 to 46mm, and the end of the air valve to which the pressure sensor is mounted is formed with a male screw 6a brought into screw engagement with a female screw formed on the pressure sensor side. By this arrangement, it is possible to eliminate the necessity of demounting and mounting the pressure sensor each time air pressure adjustment for the tire is made, and thus to prevent the air leakage caused by defective screwing or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a device for automatically detecting a tire pressure during running of an automobile and sending an alarm to a driver's seat when the detected tire pressure is abnormal. The present invention relates to a structure for mounting a pressure sensor on a tire rim.

[0002]

2. Description of the Related Art A pressure switch for detecting a tire pressure and an electromagnetic resonance circuit which is changed by the pressure switch are provided on the tire side, and the resonance state of the resonance circuit is wirelessly detected by a device provided on the vehicle body side. The tire pressure detecting device is disclosed in Japanese Utility Model Laid-Open No. 61-81396, Japanese Utility Model Laid-Open No. 1-14.
It is known from Japanese Patent No. 7706, Japanese Utility Model Laid-Open No. 2-116395, and the like.

In all of these prior arts, the tire pressure during running can be monitored by radio signals to detect the decrease in tire pressure early and send an alarm to the driver's seat. This is an excellent idea that can be realized with a simple structure that does not require any power supply device.

[0004]

However, the technique utilizing the above-mentioned principle has been installed in an ordinary automobile with a considerably reliable device, although many application studies have been conducted. Since it is not possible to offer it at a price that can be used, it is not actually installed in a commercially available car. The main reason for this is that the transmitter that includes the sensor and electromagnetic resonance circuit that is attached to the tire is subjected to severe vibrations as the vehicle runs, so it is not possible to obtain a mechanical structure that can withstand it. In order to obtain it, it is necessary to change the structure of the wheel and so on, so that it is no longer possible to use a conventionally mass-produced wheel. In a small car, there are two axles and four tires, but in a large car, there is an axle. The number of tires is 3 and the number of tires is 10. There is a reason that a rational control circuit for centrally controlling these tires could not be obtained at a low price so that it could be easily used in a practical vehicle.

The inventors of the present invention have conducted various tests on this apparatus, and as a result, have found that there is one of the technical points in the structure for mounting the pressure sensor on the tire.
That is, if the pressure sensor is attached to an existing air valve, that is, an air valve for supplying air pressure to the tire, the pressure sensor is inconveniently removed during normal tire pressure adjustment.
For this reason, we tried to install another air valve of the same standard as the existing air valve and use this as an air valve exclusively for the pressure sensor. However, the standard as an air valve is designed to be long and convenient for connection with an air compressor. However, when the pressure sensor is attached to the tip, a heavy pressure sensor is attached to the tip of a long tube-shaped air valve, and the pressure sensor part vibrates, causing a problem of strength of the air valve.

An object of the present invention is to provide an air valve structure that withstands tire vibration.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a pressure sensor and a transmitter whose resonance frequency changes according to the output of the pressure sensor are mounted on the tire side, and an antenna facing the transmitter and this antenna are provided. A control circuit for transmitting and receiving a signal and an indicator for displaying an alarm output of the control circuit are mounted on the vehicle body side, and the control circuit transmits a short pulse signal to the antenna and a transmission of the pulse signal. In response to the resonance signal transmitted by the transmitter, a frequency discrimination circuit for discriminating the frequency of the resonance signal, and a program control circuit for transmitting the alarm output by the output of the frequency discrimination circuit. In the tire pressure alarm device, the pressure sensor is attached to a dedicated air valve provided on the tire rim, and The air valve has an ETRTO standard attachment end to the tire rim, the total length L of the dedicated air valve is 28 to 46 mm, and the attachment end of the pressure sensor is formed with a male screw screwed into a female screw formed on the pressure sensor side. It is characterized by being done.

[0008]

[Function] Another air valve for mounting the pressure sensor is provided in addition to the existing air valve for supplying air pressure. This is because it is considered that the pressure sensor for the tire air pressure alarm device, once installed on the tire, rarely needs to be removed or re-installed during the entire life of the tire, and if an existing air valve is used, This is because the pressure sensor is removed and attached every time the air pressure is adjusted, and a new cause of air leakage due to defective screwing is created from that portion.

On the other hand, as an air valve for a tubeless tire, the ETRTO standard is a standard widely used worldwide, and its reliability based on its track record is well-established. Therefore, it was decided to use this ETRTO standard as the basic structure of the air valve provided to implement the present invention. Then, the length of the air valve is simply shortened to attach the pressure sensor to the tip of the pressure sensor by screwing. The height is shortened to lower the center of gravity and the vibration amplitude is also reduced. Also, as mentioned above, the pressure sensor is rarely removed,
Even if the length is shortened, there is no inconvenience in maintenance work.

It has been found that the adoption of such a structure has sufficient durability even as a result of a vibration test of an actual vehicle.

[0011]

First, the basic structure of the device of the present invention and the operating principle thereof will be described. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. A pressure sensor 1 for detecting the air pressure is attached to each tire. The sensor 1 is a pressure switch whose contacts are closed when the tire air pressure is above a predetermined value and open when the tire air pressure is below a predetermined value. A transmitter 2 is electrically connected to this pressure switch. This transmitter 2 is a resonant circuit. The pressure switch of the pressure sensor 1 changes the capacitance of the capacitor of the resonance circuit and changes the resonance frequency.

An antenna 3 is installed on the vehicle side so as to face each transmitter 2. The antenna 3 is provided for each tire and is connected to the control circuit 4 by electric wiring. The output of the control circuit 4 is connected to an indicator (lamp) 5 provided in the driver's seat.

FIG. 2 is a diagram for explaining the operating principle of the apparatus of this embodiment. The pressure sensor 1 is a pressure switch, and the contact 7 is closed when the tire pressure is equal to or higher than a predetermined value, but the contact 7 is opened when the tire pressure is lower than the predetermined value.
In the transmitter 2, there is one coil L1 and capacitors C1 and C2 connected in parallel to the coil L1, of which the capacitor C1 is connected via the contact 7 of the pressure switch. There is. Therefore, when the tire air pressure is sufficiently high, the two capacitors C1 and C2 are connected in parallel, but when the tire air pressure is low, the capacitor C1 is disconnected and the capacitor C2 is disconnected.
Only the coil L1 is connected.

In this way, the resonance frequency of the transmitter 2 changes according to the opening / closing of the contact 7. Incidentally, the resonance frequency is 87 kHz when the contact 7 is closed and the two capacitors are in parallel, and the resonance frequency is 140 kHz when the capacitor C1 is disconnected.

FIG. 3 is a block diagram of the control circuit 4. The antenna 3 is connected to the terminal 10. Oscillator 11
Then, a pulse having a short width is oscillated (in this embodiment, the pulse width is several μS and the repetition time is several tens μS), amplified by the amplifier 12 and transmitted from the antenna 3 as an electromagnetic wave. When this electromagnetic wave responds to the coil L1 of the transmitter 2,
The resonance circuit composed of the coil L1 and the capacitors C1 and C2 is stimulated to sustain damped oscillation at the resonance frequency. This resonance frequency becomes an electromagnetic wave, which is captured by the antenna 3 and input from the amplifier 13 to the frequency discriminating circuit 14. Here, the resonance frequency is detected and input to the program control circuit 15. This operation is sequentially executed for each wheel under the control of the program control circuit 15, and if any decrease in tire air pressure is detected, an alarm output is sent to the display terminal 19 and the indicator (lamp) 5 in the driver's seat is turned on. Let

Here, a dedicated air valve for mounting a pressure sensor of the tire air pressure alarm device, which is a feature of the present invention, will be described. FIG. 4 is a cross-sectional view showing the structure of a dedicated air valve in the apparatus of the present invention, FIG. 5 is a view showing a connected state of a pressure sensor and a transmitter in the apparatus of the present invention, and FIG. 6 is a pressure sensor in the apparatus of the present invention. It is a figure which shows the attachment state to a tire rim of a transmitter.

The pressure sensor 1 used in the apparatus according to the embodiment of the present invention is attached to a dedicated air valve 6 provided on a tire rim 8 as shown in FIG.
Is an ETR that has been used extensively worldwide and has demonstrated high reliability.
It has a mounting end based on the TO standard, and is mounted on the tire rim 8 with a nut 6c via an O-ring 6b, and air leakage is prevented by the O-ring 6b. Further, the total length thereof is set to 28 mm to 46 mm, and an external thread 6a which is screwed into an internal thread formed on the pressure sensor 1 side is formed at the end portion to which the pressure sensor 1 is attached.

As described above, by providing the air valve dedicated to the pressure sensor in addition to the existing air valve for supplying the air pressure, the pressure sensor 1 is adjusted every time the tire air pressure is adjusted.
It is possible to remove the trouble of removing and re-installing after adjusting the air pressure.

Frequent attachment and detachment causes a new cause of air leakage due to improper screwing when the pressure sensor 1 is screwed, but in the embodiment of the present invention, the state of attachment is removed. As such, it does not cause such problems.

Furthermore, since the height of the air valve is shortened and the pressure sensor is attached to the tip of the pressure sensor by screwing,
The center of gravity is lowered, vibration can be reduced, and durability of the air valve can be improved.

[0021]

As described above, according to the present invention, a dedicated air valve for a pressure sensor is attached with a low center of gravity so as to reduce the vibration amplitude, so that the pressure sensor can be removed every time the air pressure is adjusted. There is an effect that it is possible to eliminate the installation work, prevent the air leakage caused by the screwing failure, and sufficiently secure the durability strength against the vibration of the air valve.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation principle of the device according to the embodiment of the present invention.

FIG. 3 is a block configuration diagram of a control circuit in the device according to the embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing the configuration of an air valve dedicated to the pressure sensor in the device of the embodiment of the present invention.

FIG. 5 is a diagram showing a connected state of a pressure sensor and a transmitter in the device of the embodiment of the present invention.

FIG. 6 is a view showing how the pressure sensor and the transmitter in the device of the embodiment of the present invention are attached to the tire rim.

[Explanation of symbols]

 1 Pressure Sensor 2 Transmitter 3 Antenna 4 Control Circuit 5 Indicator (Lamp) 6 Air Valve 6a Male Thread 6b O-Ring 6c Nut 7 Contact 8 Tire Rim 10 Terminal 11 Oscillator 12, 13 Amplifier 14 Frequency Discrimination Circuit 15 Program Control Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Toyofuku 3-5-5 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Masato Sotachi 6-1188-8 Shimizu, Higashiyamato-shi, Tokyo

Claims (2)

[Claims] 1. A pressure sensor and a transmitter whose resonance frequency changes according to the output of the pressure sensor are mounted on the tire side, an antenna facing the transmitter, and a control circuit for transmitting and receiving signals to and from the antenna. An indicator for displaying an alarm output of this control circuit is attached to the vehicle body side, and the control circuit transmits a short pulse signal to the antenna, and the transmitter transmits in response to the transmission of the pulse signal. In the tire pressure warning device, the tire pressure warning device includes a receiving circuit for receiving a resonance signal, a frequency discriminating circuit for discriminating the frequency of the resonance signal, and a program control circuit for outputting the warning output by the output of the frequency discriminating circuit. The sensor is attached to a dedicated air valve provided on the tire rim. ET is mounting end to the arm
It is RTO standard, and the total length L of its dedicated air valve is 28.
The tire air pressure alarm device is characterized in that a male screw threaded to a female thread formed on the pressure sensor side is formed at a mounting end of the pressure sensor. 2. An air valve in which a mounting end to a tire rim is ETRTO standard, a total length L thereof is 28 to 46 mm, and a mounting screw of the pressure sensor is formed with a male screw.