JPH07290915A - Small size transmitter for pressure switch of tire air-pressure alarm device - Google Patents

Abstract

PURPOSE:To prevent attenuation of the transmitting level of a small size transmitter for a tire air-pressure alarm device caused by an impact, centrifugal force or humidity while running. CONSTITUTION:The small size transmitter for a pressure switch of a tire air- pressure alarm device has a transmitting base 45, a battery 49 and a cylindric antenna 50, all of which are mold casted with a silicone resin, installed inside a cylindric body composed of a metal cap body 42, equipped with an insulated pin holder 43 in its central part, and a resin cover, and a lead wire connected to the transmitting base 45 is connected to the cap body 42, while a jumper wire 47 is connected to a contact probe 44 fixed to the pin holder 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small transmitter for a tire pressure warning device for detecting an abnormality in tire pressure and giving a warning to a driver in a vehicle.

[0002]

2. Description of the Related Art A tire air pressure warning device for detecting a decrease in vehicle tire air pressure and notifying the driver of this is disclosed in Japanese Utility Model Laid-Open No. 2-70204. Transmitter 1 in this conventional tire pressure warning device
As shown in FIG. 3, is composed of a lower half pressure switch 3 and an upper half transmission unit 13 and is fixed to a wheel rim 18. The pressure switch 3 has an air inlet 4 at the center.
5, a bellows 6 made of rubber that is vertically displaced according to the tire internal pressure, a fixed ring 8 having an inwardly projecting flange surface as a contact 7, and a movable ring having a contact 9 on the flange portion. 10, a coil spring 11 for pressing the movable ring downward, and a conductive plate 12, and the transmitter 13 includes a signal processing circuit 14 by a microcomputer.
And a battery 15, an antenna 17, and a lid 16. Then, the pressure switch 3 is turned on / off according to the tire air pressure, this state is detected, and a signal is transmitted to a receiver (not shown) on the vehicle body side by radio waves to warn the driver. It was

However, since the pressure switch 3 uses a rubber bellows 6 as a diaphragm, there is a problem in durability, and the movable ring 10 is only fixed by the coil spring 11 and the bellows 6. Therefore, even when the tire pressure is normal, the movable ring and the fixed ring come into contact with each other due to vibration or the like, and the same as when the contact 7 and the contact 9 are closed, which may cause a false alarm. Further, since a rubber bellows is used, deterioration is fast and reliability is lowered.

Therefore, the applicant of the present application has filed an application (No. 5-65040 of Japanese Utility Model Publication No. 5-65040) for a pressure switch having a novel structure which solves the drawbacks of the pressure switch. This pressure switch is, as shown in FIG. 4, a cup-shaped bellows case 22 having a contact screw 24 and an air inlet 23 at the bottom.
And a frame-shaped metal support base 28 provided with a terminal 25 and a stopper 26 above and below the shaft and a flange 27 in the middle, and a flange 2 of the support base 28 so as to enclose the lower stopper 26.
A metal bellows 29 integrally provided on the lower surface of section 7,
A pressure switch (21) comprising a housing (32) formed so as to enclose the terminal (25) above the metal support base (28) via an insulating packing (31), the contact screw (24) being provided at the center of the lower surface of the metal bellows (29). A spherical convex portion 30 forming a contact point with is formed.

Therefore, in the pressure switch 21 described above, it is possible to solve the problem of the conventional pressure switch 3 shown in FIG. 3 such as a false alarm due to vibration or the like and the deterioration of the rubber bellows, and further, to contact the metal bellows 29 itself. By forming the, the number of extra parts and the number of assembling steps are reduced.

[0006]

In the conventional transmitter 1 shown in FIG. 3, the transmitter 13 includes a signal processing circuit 14 including a microcomputer, a battery 15, an antenna 17, and a lid 1.
6, the signal processing circuit 14 has various electronic components mounted on a printed circuit board.
When the transmitter 1 is attached to the wheel rim 18, external impact or centrifugal force is applied to damage or destroy soldered parts of various electronic components forming the transmitter 13, or When the electronic components are provided adjacent to each other, dew condensation occurs between them, which causes attenuation of the transmission level and malfunction.

[0007]

The present invention has been made to prevent the transmission level from being attenuated due to the impact, centrifugal force, and humidity as described above. A tire pressure alarm completely molded with a silicone resin is provided. It is intended to provide a small transmitter for a pressure switch of a device. That is, the small transmitter 4 for the pressure switch of the tire pressure warning device of the present invention.
The contact probe 44 includes a metal cap body 42 having an insulative pin holder 43 fixed to the upper inner portion thereof, and a pin 44 having a piston 44a at the center thereof which is vertically slidable. And the transmission board 45 is arranged above the cap body 42 with a space therebetween, and the lead wire 4 is provided from the center of the lower surface of the transmission board 45.
6 of the contact probe 4 and the tip of the contact probe 4
4, and a jumper wire 47 is hung from the side edge of the lower surface to connect to the metal cap body 42. Above the transmission board 45, two power supply terminals 48a, 48 are provided.
The battery 49 is fixed via b, and above the battery 49,
Disc-shaped antennas 50 are arranged at intervals, and the antennas 50 and the transmission board 45 are connected by a power supply line 51. The transmission board 45, the battery 49, and the battery 49 are provided on the outer side of the cap body 42. A cylindrical resin cover 52 is fixed so as to wrap the antenna 50 and the like, and then a silicon resin 53 is injected into the inside, and then the upper opening of the resin cover 52 is covered with a lid 5.
It is characterized by being sealed in 4. Further, a coil 55 is connected in series to a power supply line 51 connecting the antenna 50 and the transmission substrate 45 according to the present invention to prevent a leakage current and obtain a stable transmission output.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The small transmitter 41 of the tire air pressure alarm device of the present invention has a female screw 42a provided on the inner surface of a metal cap body 42, and the female screw 42a is screwed into the housing 32 of the pressure switch 21 shown in FIG. It is like this. A pin holder 43 is fixed above the inner side of the metal cap body 42, and a contact probe 44 is provided at the center of the pin holder 43.
Is fixed and the lower end of the piston 44a is
The upper end of the terminal 25 of the pressure switch shown in FIG.

A transmission board 45 having electronic components 45a and 45b is arranged above the cap body 42 with a space therebetween, and a lead wire 46 is hung from the center of the lower surface of the transmission board 45. Its tip is connected to the contact probe 44, and a jumper wire 47 is hung from the side of the lower surface of the transmission board 45 and connected to the upper surface of the cap body 42.

Further, above the transmission board 45, a battery 49 is fixed between two power supply terminals 48a and 48b which are soldered upright from both side edges of the transmission board 45. Further, a disc-shaped antenna 50 is arranged above the battery 49 with a gap therebetween.
0 and the transmission board 45 are connected to each other by a power supply line 51 (linear φ0.6
mm, length 8.0 mm, tin-plated wire).

A tubular resin cover 52 is for enclosing the transmission board 45, the battery 49, the antenna 50, etc. The resin cover 52 is fixed to the upper outer portion of the cap body 42. . And the resin cover 5
After the silicon resin 53 is injected and solidified through the second upper opening, the upper opening is hermetically sealed with the lid 54.
Therefore, since the inside of the above-described small transmitter 41 of the present invention is molded with the silicone resin 53, when the transmitter 41 is attached to the wheel rim, external impact or centrifugal force is applied. However, the soldered parts of various electronic parts will not be damaged or destroyed, and even if the electronic parts are installed adjacent to each other, no condensation will occur between them, causing attenuation of the transmission level and malfunction. There is no fear.

[0011]

Other Embodiments In the embodiment shown in FIG. 1, the feeder line 5 for connecting the antenna 50 and the transmission board 45 is used.
Since 1 is linear, the high frequency power to be transmitted from the transmission substrate 45 to the antenna 50 leaks at the portion of the power supply line 51, so that the transmission efficiency is slightly reduced and the transmission level is lowered.

FIG. 2 shows another embodiment showing a connection state between the antenna 50 and the transmission board 45. In this embodiment, a coil 55 is connected in series to a power supply line 51 that connects the antenna 50 and the transmission board 45.
The inductance L of the coil 55 may be obtained by actually changing the value of the inductance L variously, measuring the transmission output at that time, and using the value of the inductance when the transmission output is the largest. According to an experiment conducted by the present inventor, it is most preferable that the inductance of the coil 55 is 3.3 to 4.3 μH, and the transmission output is increased by 5 to 6 db as compared with the case where the coil 55 is not provided.

[0013]

The operation of the transmitter of the present invention will be described below with reference to FIG.
A description will be given based on FIGS. 4 and 5. FIG. 5 is a block diagram of the transmitter of the present invention. In this figure, the transmission board 4
When the battery for supplying power to 5, the cap body 42, which is an open terminal connected in series, and the contact probe 44 are short-circuited by the contact on the pressure switch side, power is supplied to the transmitting substrate 45 and the radio wave is transmitted to the antenna. Output via 50. Next, the operation when the transmitter 41 is actually attached to the pressure switch 21 will be described. In the conventional pressure switch shown in FIG. 4, the spherical protrusion 27 is electrically connected to the terminal 25 via the metal bellows 29 and the metal support base 28, while the contact screw 24 is connected to the housing via the bellows case 22. It is in continuity with 32. When the tire air pressure is equal to or higher than the set value, the terminal 25 and the housing 32 are not electrically connected by the insulating packing 31. Further, the terminal 25 and the housing 32 are brought into conduction.

When the transmitter 41 is attached to the pressure switch 21, a cap body 42 provided with a screw 42a is provided.
Is screwed into the housing 32 of the pressure switch, and at the same time, the upper end portion of the terminal 25 and the tip end portion 44a of the contact probe 44 come into contact with each other and become conductive. The cap body 42 is connected to the transmission board 45 via the jumper wire 7 and the contact probe 44 via the lead wire 46. When the cap body 42 and the contact probe 44 are short-circuited, a radio wave is output. In other words, when the tire air pressure falls below the set value, the spherical protrusion 27 of the pressure switch and the contact screw 24 are connected, and at the same time, the cap body 42 of the transmitter and the contact probe 44 are short-circuited to supply power and transmit. A radio wave is output from the antenna 50 from the substrate 45 via the power supply line 51.

[0016]

As described above, the small transmitter of the present invention is
This is a very simple system in which the power is turned on and off by transmitting and closing the contacts on the pressure switch side, and radio waves are transmitted. By using the terminal for taking in the open / closed state of the contact also as the cap main body 42 for mounting on the pressure switch side, the structure is simplified and the reliability is improved. In addition, by molding the transmission substrate 45, the battery 49, the antenna 50, the power supply line 51, the jumper line 47, the lead wire 46, etc. with the silicone resin 53, even when mounted in a severe environment such as a tire wheel, various electronic components No damage or destruction occurs in the soldered portion, and even if electronic components are provided adjacent to each other, dew condensation does not occur between them. Further, by connecting the coil 55 to the power supply line 51 in series, the transmission output can be improved by 5 to 6 db as compared with the case without the coil.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing a small transmitter for a pressure switch of a tire pressure warning device of the present invention.

FIG. 2 is a partially enlarged perspective view showing another embodiment of the connection state of the antenna and the transmission board.

FIG. 3 is a vertical cross-sectional view of a transmitter in a conventional tire pressure warning device.

FIG. 4 is a vertical cross-sectional view showing a pressure switch of a conventional tire air pressure alarm device.

FIG. 5 is a block diagram of a small transmitter of the tire pressure warning device of the present invention.

[Explanation of symbols]

41 Small transmitter. 42 Metal cap body. 43 pin holder. 44
Contact probe. 45 Transmitter board.
46 leads. 47 Jumper wire.
48a, 48b Power supply terminal. 49 batteries
50 Disc-shaped antenna. 51 Power line. 52 Cylindrical resin cover.
53 Silicone resin. 54 Lid. 55
coil.

Claims (2)

[Claims] 1. An insulative pin holder 43 is fixed to an upper inner portion of a metal cap main body 42, and the pin holder 43 is fixed.
A contact probe 44 having a piston 44a vertically slidable at its tip is fixed to the center of the transmission board 4 above the cap body 42.
5, the lead wire 46 is hung from the central portion of the lower surface of the transmission substrate 45 to connect the tip end thereof to the contact probe 44, and the jumper wire 47 is hung from the side edge portion of the lower surface. Connected to the cap body 42, and above the transmission board 45, two power supply terminals 48 are provided.
A battery 49 is fixed via a and 48b, and a disc-shaped antenna 50 is arranged above the battery 49 with a gap therebetween, and the antenna 50 and the transmission substrate 45 are connected by a power supply line 51. However, on the outer side of the cap body 42,
A cylindrical resin cover 52 is fixed so as to wrap the transmission substrate 45, the battery 49, the antenna 50, etc., and after a silicone resin 53 is injected into the inside, the upper opening of the resin cover 52 is sealed with a lid 54. A compact transmitter for a pressure switch of a tire pressure alarm device, which is characterized in that 2. A compact transmitter for a pressure switch of a tire air pressure alarm device according to claim 1, wherein a coil 55 is connected in series to a power supply line 51 connecting the antenna 50 and the transmission substrate 45.