JPH0231281Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an automobile tire pressure sensor.

BACKGROUND OF THE INVENTION A tire pressure alarm system for an automobile includes a tire pressure sensor attached to the rim of a tire, and a magnetic sensor attached to a stationary member, such as the back plate of a drum brake, in close opposition to the tire pressure sensor. It usually consists of a switch and an alarm device such as an alarm lamp or buzzer that is activated by the operation of the magnetically sensitive switch.

The above tire air pressure sensor has a diaphragm attached to a sensor case attached to the tire rim, on which tire air pressure acts on one side and a spring force acting on the other side, and when the tire air pressure falls below a predetermined value, the diaphragm In addition to being configured to operate by the spring force of a spring, a magnet is incorporated into the sensor case, and when the tire air pressure is above a predetermined value and the diaphragm is in a position where the diaphragm is pushed toward the spring side by the tire air pressure, the magnetic field lines of the magnet are activated. is in a state in which it does not act on the magnetically sensitive switch, but when the tire air pressure falls below a predetermined value and the diaphragm is activated by being pushed by a spring, the magnetic line of force of the magnet becomes in a state in which it acts on the magnetically sensitive switch. This is generally the case (see, for example, Japanese Utility Model Publication No. 46177/1983).

Problems to be Solved by the Invention Since the tire air pressure sensor described above is attached to the rim of the tire as described above, it is susceptible to dust that is kicked up by the rotation of the tire while driving, or when the tire is in the rain. It is extremely difficult to prevent muddy water etc. splashed up by the sensor from entering the sensor case, so it is desirable to have a sealed structure inside the sensor case if possible. However, if the inside of the sensor case is sealed, the air inside the tire that has permeated little by little over a long period of time through a diaphragm made of an elastic material such as rubber will fill the inside of the sensor case, increasing the air pressure inside the sensor case. The differential pressure between the air pressure and the air pressure inside the sensor case decreases,
A problem arises in that the diaphragm is activated by the force of the spring even though the tire air pressure has not decreased to the set pressure, and the alarm is activated.

The present invention is intended to address the problems of conventional devices as described above.

Means for Solving the Problems The present invention includes a diaphragm mounted near the opening into the tire of a sensor case mounted on the rim of the tire, and applies a pressing force opposing the tire air pressure acting on the diaphragm. A spring that acts on the diaphragm is provided inside the sensor case, and
When the tire air pressure drops below a predetermined value and the diaphragm moves due to the pressure of the spring being pushed by the spring, the magnetically sensitive switch attached to the stationary member is switched to a state where lines of magnetic force can be applied. In a tire air pressure sensor in which a removable magnet is mounted inside a sensor case, a communication hole is provided to communicate the inside of the sensor case with outside air, and a closing member made of a material that allows air to pass through the communication hole but does not allow water or dust to pass through the communication hole. It is characterized by occlusion at .

Effects According to the present invention configured as described above, the communication hole that communicates the inside of the sensor case with the outside air is closed with a closing member made of a material that allows air to pass through but does not allow water or dust to pass through. It is possible to completely prevent the problem of dust, muddy water, etc. thrown up by the rotation of the tires while driving entering the sensor case, and also to gradually pass through the diaphragm and enter the sensor case over a long period of time. The air inside the tire passes through the closing member and is discharged to the outside, completely preventing an increase in the air pressure inside the sensor case and the accompanying malfunction of the tire air pressure sensor, and ensuring reliable sensing function can be maintained for a long period of time. It is something.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In Figs. 1 and 2, 1 is a tire air pressure sensor, and the tire air pressure sensor 1 is fixed to the rim B of the tire A as shown in Fig. 3, and is attached to a stationary member such as the back plate C of a drum brake. The tire air pressure sensor 1 is arranged to closely face the magnetically sensitive switch D as the tire rotates.

As shown in FIGS. 1 and 2, the tire air pressure sensor 1 includes a lateral cylindrical portion 21 that is substantially parallel to the rim B, and a cylindrical mounting protrusion that protrudes in a direction substantially perpendicular to the lateral cylindrical portion 21. Sensor case 2 consisting of 22
An in-tire opening 21a communicating with the inside of the tire A is provided at one end of the lateral cylindrical portion 21, and a diaphragm 3 made of an elastic material such as silicone rubber is attached to the in-tire opening 21a. A spring 5 that applies a pressing force to the diaphragm 3 via the guide member 4 so as to counteract the tire internal air pressure that acts on the diaphragm 3 is provided in the lateral cylindrical portion 21 of the sensor case 2. A magnet 6 is mounted in the mounting protrusion 22 so as to be rotatable about a shaft 7, and an arm portion 8 fixed to the shaft 7 or a holding member 6a that holds the magnet 6 and a connection fixed to the guide member 4. The magnet 6 engages with the member 9, and the magnet 6 moves around the shaft 7 in conjunction with the deformation of the diaphragm 3 based on the fluctuation in the balance between the tire air pressure acting on both surfaces of the diaphragm 3 and the spring force of the spring 5. It is configured to rotate.

The tire pressure sensor 1 configured as described above has a cylindrical mounting protrusion 22 fitted into the mounting hole B' of the rim B, and an O-ring 13 and a snap spring 1.
By fixing airtightly with 4, the mounting protrusion 2
It is assembled to the rim B so that the tip of the switch 2 protrudes outside the rim B and is closely opposed to the magnetically sensitive switch D described above.

The magnet 6 is assembled in advance into a bottomed cylindrical cap member 10 made of a non-magnetic material so as to be rotatable around a shaft 7, and the cap member 10 is fitted into the mounting protrusion 22. By locking with the O-ring 12 and the snap ring 12', the tip of the mounting protrusion 22 of the sensor case 2 is attached to the cap member 10.
It is a covered structure.

A communication hole 10a is provided at the bottom of the cap member 10 to communicate the inside of the sensor case 2 with the outside air.
0 is closed by a membrane-like closing member 11 fixed to the inside of the bottom surface.

The closing member 11 is made of a porous membrane material (for example, one commercially available under the trade name Microtex) or a non-porous membrane material (for example, one commercially available under the trade name Repora), which allows air to pass through but prevents water and dust from passing through. is made of impermeable material.

In the figure, 4a is a guide roller rotatably provided on the outer circumference of the guide member 4, and as the guide roller 4a rolls on the inner circumferential surface of the lateral cylindrical portion 21, the guide member 4 is moved laterally. It is designed to be able to move smoothly in the left and right directions in the figure while maintaining an appropriate gap with the inner circumferential surface of the cylindrical portion 21.

In the above configuration, while the air pressure of the tire A is high, the air pressure is affected by the spring force of the spring 5, and the diaphragm 3 is pushed into the sensor case 2 as shown in FIG. The member 9 is in a position where it abuts one stopper surface 10b formed on the inner circumferential surface of the cap member 10, and the magnet 6 is held in a horizontal position.

In this state, even if the bottom surface of the cap member 10 approaches the magnetically sensitive switch D attached to the stationary member due to the rotation of the tire A, the line of magnetic force of the magnet 6 will not act on the magnetically sensitive switch D, and the alarm will not be activated. I can't utter it.

When the tire air pressure becomes low and becomes less than the set value, the spring force of the spring 5 deforms the diaphragm 3 inward to the tire A, and the guide member 4 moves the inside of the lateral cylindrical portion 21 into the tire. The connecting member 9 moves toward the opening 21a, and reaches a position where the connecting member 9 is in contact with the other stopper surface 10c formed on the inner circumferential surface of the cap member 10, as shown in FIG. The cap member 10 is rotated and held in a state facing toward the bottom surface of the cap member 10.

Then, due to the rotation of tire A, cap member 1
Each time the bottom of the magnet 6 comes to a position close to and facing the magnetically sensitive switch D, the magnetically sensitive switch D is activated by the magnetic force lines of the magnet 6, and an alarm (not shown) is activated by the activation signal of the magnetically sensitive switch D. to alert the driver.

In the above, the air inside the tire passes through the diaphragm 3 made of silicone rubber or the like and enters the sensor case 2 little by little over a long period of time.
The air passes through the air and is discharged to the outside from the communication hole 10a, so that the air pressure inside the sensor case 2 never increases, and malfunction of the tire air pressure sensor is completely prevented.

Also, the blocking member 11 prevents dust, muddy water, etc. thrown up by the rotation of the wheels from entering the sensor case 2.
It does not invade the inside of the body and can maintain reliable sensing functions for a long period of time.

In addition to the embodiment shown in the drawings, the present invention is applicable to, for example, a magnet fixed in a sensor case so as to be close to and opposite to a magnetically sensitive switch, and a magnetic field line shielding member that shields the magnetic lines of force of the magnet in a position that covers the front surface of the magnet in conjunction with the deformation movement of the diaphragm. It can be applied to all types of tire pressure sensors, such as a tire pressure sensor that is mounted inside a sensor case so that it can be moved to a position away from the front of the magnet.

Further, in the illustrated embodiment, the membrane-like closing member 11 is fixedly attached to the inner surface of the communication hole 10a by means of adhesion or the like. It is also possible to have a structure in which the communication hole 10a is closed.

Effects of the invention As described above, according to the invention, the extremely simple structure prevents dust, water, etc. from entering the interior, and there is no increase in internal air pressure and associated malfunction, and it can be used for a long period of time. It is possible to provide a tire air pressure sensor that can maintain a reliable tire air pressure sensing function, and it is also possible to prevent a sudden drop in tire air pressure with a closing member even in the event of an accident where the diaphragm is damaged, thereby increasing safety. It is possible to improve this, and it is possible to bring about a great practical effect.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing an embodiment of the present invention. FIG. 1 shows a case where the tire internal air pressure is normal pressure, and FIG. 2 shows a case where the tire internal air pressure has decreased. FIG. 3 is an explanatory cross-sectional view showing an example of how the tire air pressure sensor shown in FIGS. 1 and 2 is mounted. 1...Tire air pressure sensor, 2...Sensor case, 3...Diaphragm, 5...Spring, 6
... Magnet, 10 ... Cap member, 10a ... Communication hole, 11 ... Closing member.

Claims (1)

[Scope of utility model registration request] A diaphragm is attached near the opening into the tire of the sensor case attached to the tire rim,
A spring is provided in the sensor case that applies a pressing force to the diaphragm that is opposite to the tire air pressure acting on the diaphragm, and when the tire air pressure drops below a predetermined value and the diaphragm deforms and moves due to the pressing force of the spring, it stops. In a tire air pressure sensor in which a magnet is provided in a sensor case to switch to a state in which lines of magnetic force act on a magnetically sensitive switch attached to a member side, a communication hole is provided that communicates the inside of the sensor case with outside air, and the communication hole is A tire air pressure sensor for an automobile, characterized in that it is closed with a closing member made of a material that allows air to pass through but does not allow water or dust to pass through.