JPH0781336A - Tire inflation pressure detector - Google Patents

Abstract

PURPOSE:To provide a tire inflation pressure detector that is simple in structure and can reduce the cost of production as well as to enjoy high detection accuracy. CONSTITUTION:A magnet 11 to advance or retreat in a direction of separation from a tire according to tire inflation pressure is integrally installed together with the tire after making an axis connecting both N and S poles of this magnet 11 accord with the moving direction, while a detecting sensor 14 detecting the movement of this magnet 11 is integrally installed together with a car body at an axial side of this magnet 11, and the detecting sensor 14 and the magnet 11 are set up respectively so as to reverse the polarity of the magnet 11 to be detected by the detecting sensor 14 differently at each time when tire air pressure is within the preset adequate range as well as when it is less than this adequate range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire pressure detection device suitable for detecting and monitoring the air pressure of a tire mounted on a vehicle body of an automobile or the like to improve safety.

[0002]

2. Description of the Related Art Conventionally, for example, a tire air pressure detecting device mounted on an automobile is equipped with a pressure sensor for each wheel, and the air pressure of the tire is directly detected by this pressure sensor. A transmitter for transmitting the output of the pressure sensor is provided on the rotating tire side, while an antenna or the like for receiving a signal from the transmitter is provided on the vehicle body side for transmitting the signal.

[0003]

However, in the conventional tire pressure detecting device as described above, since a transmitter, an antenna, etc. for signal transmission are required,
There are problems that the structure is complicated and the manufacturing cost is high. The present invention has been made in consideration of the above points, and an object of the present invention is to provide a tire air pressure detection device that has a simple structure, can reduce manufacturing costs, and has high detection accuracy.

[0004]

SUMMARY OF THE INVENTION The present invention is a tire air pressure detecting device for detecting air pressure of a tire rotatably attached to a vehicle body, the device moving forward and backward in a direction away from the tire according to the tire air pressure. A magnet is provided integrally with the tire with an axis line connecting the N pole and the S pole of the magnet aligned with the advancing / retreating direction, and a detection sensor for detecting advancing / retreating of the magnet is provided on the lateral side in the axial direction of the magnet. The magnet that is provided integrally with the vehicle body and that is detected by the detection sensor when the air pressure of the tire is within a preset suitability range and when the magnet and the detection sensor are below the suitability range It is characterized in that they are arranged so that the polarities of are reversed.

[0005]

In the tire air pressure detecting device of the present invention, the magnet moves forward and backward in the direction away from the tire when the tire air pressure is within the preset proper range and when it is below the proper range to detect the sensor. The polarity of the magnet detected in step 1 is reversed, which makes it possible to detect whether the tire air pressure is within the proper range.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS. FIG. 1 shows a part of an automobile equipped with a tire pressure detecting device according to the present invention.
In this figure, reference numeral 1 is a vehicle body, 2 is a wheel rotatably attached to the vehicle body 1 around an axis, and 3 is a tire integrally mounted on the wheel 2. The tire air pressure detection device A includes a pressure sensing unit 4 that senses the air pressure of the tire 3 and a detection unit 5 that senses the displacement of the pressure sensing unit 4.

The pressure sensitive portion 4 is fitted into the rim portion 2a of the wheel 2 and provided integrally with the wheel 2 so as to have an axis in a direction orthogonal to the rim portion 2a, in other words, in a direction away from the tire 3. Has been. As shown in FIG. 2, a communication hole 6 is formed in the pressure-sensitive portion 4, and the inside 4a of the pressure-sensitive portion 4 communicates with an air chamber 7 surrounded by the wheel 2 and the tire 3. An air chamber 7 is provided inside the pressure sensitive portion 4a.
A diaphragm 8 made of rubber for partitioning the inside and the outside of the shaft, a shaft 9 that can move back and forth in the axial direction, and this shaft 9
A spring 10 for urging the tire toward the inside of the tire 3,
A permanent magnet (magnet) 1 attached to the tip of the shaft 9 so that the line connecting the N-pole side and the S-pole side coincides with the axis.
1 and 1. In the pressure-sensitive portion 4 having such a configuration, the diaphragm 8 is deformed in the axial direction of the pressure-sensitive portion 4 according to the air pressure of the tire 3, whereby the permanent magnet 11 is formed.
Is configured to move forward and backward together with the shaft 9 in the axial direction.

On the other hand, as shown in FIG.
It is attached to a support portion 12 integrally fixedly connected to the vehicle body 1 via a trailing arm. This detector 5
Is composed of a support arm 13 attached to the support portion 12, and a detection sensor 14 formed of, for example, a Hall element, which is attached to the tip of the support arm 13 so as to be positioned on the axial side of the pressure sensitive portion 4. It is configured. This detection sensor 14 uses the Hall effect of the Hall element to make the permanent magnet 1
When the air pressure of the tire 3 is within a preset appropriate range, the N pole of the permanent magnet 11 is detected as shown in FIG. When it is below the appropriate range, it is arranged at a position where the S pole of the permanent magnet 11 is detected as shown in FIG.

In the tire air pressure detecting device A having the above-mentioned structure, when the air pressure of the tire 3 is within the preset proper range, the pressure sensing portion 4 is in a state as shown in FIG. 2 (a). Therefore, the detection sensor 14 of the detection unit 5 detects the N pole of the permanent magnet 11. Then, when the air pressure of the tire 3 falls below an appropriate range for some reason, as shown in FIG. 2B, the diaphragm 8 is deformed toward the air chamber 7 side in accordance with this pressure drop, and the shaft 9 Is moved by the spring 10 to move to the air chamber 7 side, and accordingly, the permanent magnet 11 moves to the air chamber 7 side. Then, the detection sensor 14 of the detection unit 5
Then, it is detected that the polarity of the permanent magnet 11 is reversed from the N pole to the S pole. The reversal of the polarity of the permanent magnet 11 detected by the detection sensor 14 is transmitted to a control circuit (not shown),
As a result, it is determined that the air pressure of the tire 3 has fallen below the appropriate range, and the pressure drop is displayed by turning on the indicator lamp provided in the driver's seat.

In the tire air pressure detecting device A as described above, it is possible to detect the decrease in the air pressure of the tire 3 and improve the safety, and further, the transmitter and the antenna for signal transmission as in the prior art are unnecessary. Since it has a simple structure, the manufacturing cost can be reduced. Also,
The tire air pressure detection device A has a structure in which the permanent magnet 11 that moves forward and backward according to a change in the air pressure of the tire 3 is used, whereby the detection sensor 14 detects a decrease in the air pressure of the tire 3. As such a structure for detecting the advancing / retreating of the magnet, for example, as in the tire air pressure detecting device B shown in FIG. It is conceivable that the detection sensor 21 composed of is opposed. In such a tire air pressure detection device B, when the air pressure of the tire 3 changes, the magnet 20 moves back and forth, and the distance between the magnet 20 and the detection sensor 21 changes. Then the detection sensor 21
When the detected value of the magnetic field strength of the magnet 20 detected in 1 changes and deviates from the preset fixed range, it is determined that the air pressure of the tire 3 has fallen below the appropriate range. However, the tire pressure detection device B
Then, since the change in the magnetic field strength of the magnet 20 detected by the detection sensor 21 is a continuous amount, in order to accurately determine whether or not the air pressure of the tire 3 is within an appropriate range, an amplifier,
A complicated discrimination circuit including an A / D converter, a comparison circuit, etc. is required. On the other hand, in the tire air pressure detection device A having the above-described structure, when the air pressure of the tire 3 is within the proper range and when it is below the proper range, the permanent magnet 11 detected by the detection sensor 14 is detected. Since the polarities are reversed, the discrimination is very easy, and therefore high detection accuracy can be obtained with a simple structure, and the manufacturing cost can be further reduced.

In the above embodiment, the detection sensor 1
4, the N pole of the permanent magnet 11 is detected when the air pressure of the tire 3 is within a preset proper range, and the S pole of the permanent magnet 11 is detected when the air pressure of the tire 3 is below the proper range. However, it goes without saying that the same effect can be obtained even if the direction of the permanent magnet 11 is reversed.

[0012]

As described above, according to the tire air pressure detecting device of the present invention, the magnet moving forward and backward in the direction away from the tire according to the tire air pressure is connected to the axis line connecting the N pole and the S pole of the magnet. Is provided integrally with the tire so as to correspond to the advancing / retreating direction, and a detection sensor for detecting advancing / retreating of the magnet is provided integrally with the vehicle body on the axial side of the magnet, and the tire air pressure is set in a predetermined appropriate range. When the tire pressure is within the proper range, the magnet moves forward and backward depending on whether the tire pressure is within the proper range or not. Very easy to determine. Therefore, it is possible to obtain high detection accuracy with a simpler structure and to reduce the manufacturing cost as compared with the related art.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a tire air pressure detection device according to the present invention.

FIG. 2 is a front sectional view showing a detection principle of the tire air pressure detection device.

FIG. 3 is a front sectional view showing an example of another tire air pressure detection device.

[Explanation of symbols]

1 ... Car body, 3 ... Tire, 11 ... Permanent magnet (magnet), 14
... Detection sensor, A ... Tire pressure detection device

Claims (1)

[Claims] 1. A tire air pressure detection device (A) for detecting air pressure of a tire (3) rotatably attached to a vehicle body (1), the tire (3) according to the air pressure of the tire (3). ) A magnet (11) that moves back and forth in a direction away from
Is provided integrally with the tire (3) with an axis line connecting the N pole and the S pole of the magnet (11) aligned with the advancing / retreating direction, and detects the advancing / retreating of the magnet (11).
4) is integrally provided with the vehicle body (1) on the axial side of the magnet (11), and the air pressure of the tire (3) is preset by the magnet (11) and the detection sensor (14). The tire is characterized in that the polarities of the magnets (11) detected by the detection sensor (14) are reversed between the appropriate range and the appropriate range or less. Air pressure detection device (A).