JPS62257039A - Apparatus for detecting air pressure of tire for vehicle - Google Patents

Abstract

PURPOSE:To dispense with a special seal structure, to miniaturize a whole, to reduce cost and to enhance mount work, by providing a pressure detection means being a part for detecting the air pressure of a tire for a vehicle in a tire case. CONSTITUTION:When the air pressure in a tire casing is a normal state and the dimensional displacement quantity of bellows 19 in the axial direction thereof is little, a movable contact 20 and a fixed contact 21 are held to a state spaced apart from each other. When the air pressure in the tire casing abnormally lowers and the bellows 19 dimensionally displaces by predetermined quantity or more in the axial direction, the movable contact 20 contacts the fixed contact 21 to conduct load 25. The load 25 generates a transmission signal to send the same to the receiving device provided in a vehicle.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) (Prior Art) - In recent years, for example, devices have been added to automobiles that issue an alarm when the air pressure of the tires falls below a predetermined pressure. In this case, it is necessary to detect a decrease in tire air pressure even while the vehicle is running. Conventionally, for such detection, a pressure switch is attached directly to the tire valve, and the tire air pressure is detected through the tire valve.

(Problem to be Solved by the Invention) However, in the above conventional configuration, the tire air pressure is obtained through the tire valve with respect to the pressure switch.]2.The pressure switch is sometimes installed using a seal between the tire valve and the pressure valve. This has to be done strictly, and as a result, the sealing structure has to be sufficiently applied, which not only leads to an increase in size and cost, but also has the problem of extremely poor workability when installing the pressure switch. there were. Furthermore, since the pressure switch is mounted exposed to the outside, there is a risk of damage due to external forces and poor environmental resistance, which may lead to early deterioration of the sealing performance between the tire valve and the pressure switch. There is, etc.
There was also the problem of poor reliability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the need for a special seal structure, to reduce the overall size and cost, and to improve installation workability, as well as to improve reliability by improving environmental resistance. It is an object of the present invention to provide a vehicle tire air pressure detection device that can achieve effects such as improvement in air pressure.

[+14 features of the invention] (Means for solving the problems) The air pressure detection device for a vehicle tire according to the present invention is a tire comprising a metal tire wheel and a metal valve pipe electrically insulated. The device is intended for vehicle tires equipped with a valve, and a two-terminal pressure detector stage is provided in the tire casing to generate a detection signal according to the magnitude of the air pressure inside the tire casing, and this pressure detection means is provided. One terminal of the tire wheel is the tire wheel, and the other terminal is the valve pipe.

(Function) A detection signal corresponding to the air pressure in the tire casing is output from the pressure detection means, and the detection signal can be obtained from between the tire wheel and the valve pipe of the tire valve. At this time, since both the tire wheel and the valve pipe are exposed to the outside, the detection signal can be easily taken out even though the pressure detection means is provided within the tire casing.

(Embodiment) In FIG. 1, reference numeral 1 denotes a metal tire wheel to which, for example, an automobile tubeless tire (not shown) is attached, and this is grounded to the body via an axle shaft or the like.

2 is a tire valve, which will be described below.

That is, the bushing 3 is made of an insulating material such as rubber, and is provided for airtightly inserting and supporting the entire tire valve 2 into the through hole 1a of the tire wheel 1. Reference numeral 4 denotes a metal valve pipe provided to penetrate the bush 3, and is positioned so as to extend from the proximal end side to the tire casing (inside the tire body) of the front tire tubeless tire. At this time, since the bushing 3 made of an insulating material is interposed between the valve pipe 4 and the tire wheel 1, the valve pipe 4 and the tire wheel 1 are electrically insulated. The valve pipe 4 is provided with a vent hole 4a communicating with the inside of the tire casing on its base end side, and threaded portions 4b and 4c are provided on the outer periphery of the base end side and the tip side, respectively. Further, a flange portion 4d is provided on the outer periphery of the intermediate portion so as to be adjacent to the threaded portion 4c.

Reference numeral 5 denotes an inner valve of a well-known configuration screwed into the valve pipe 4, and the inner valve 5 includes a rod 6 that is movable in the axial direction and a compression coil spring that constantly urges the rod 6 in the direction of the arrow Ah. 7. A stopper 8 for removing the compression coil spring 7, a valve main body 9 provided on the rod 6. The valve holder 11 is airtightly fixed to the inner circumferential wall of the valve pipe 4 via a packing 10, an I female thread 12, and the like. In such an inner valve 5, the valve main body 9 is always in pressure contact with the valve holder 11 and is in a "closed" state, and from this state, the rod 6
When the valve main body 9 is pressed against the valve holder 11 and is moved in the opposite direction of arrow A, the pressure contact state of the valve body 9 with respect to the valve holder 11 is released, and the valve is opened.
begins to exhibit a condition.

On the other hand, 13 is a terminal fitted on the outer periphery of the valve pipe 4, which is held between a nut 14 screwed onto a threaded portion 4C at the tip of the valve pipe 4 and a flange portion 4d of the valve pipe 4. It is fixed in this state and is electrically connected to the valve pipe 4. Note that a lead wire 13a is connected to this terminal 13. 15 is a threaded portion 4 at the tip of the valve pipe 4.
The cap is screwed onto C to remove the pipe, and a gasket 16 is provided inside the cap.

Now, reference numeral 17 denotes a holding case in the shape of, for example, a flat, nine-bottomed cylinder, which is provided inside the tire casing, and is made of an insulating material such as plastic. Base end side threaded portion 4b of valve pipe 4
It is screwed on. Reference numeral 18 denotes a metal cover attached to the periphery of the holding case 17 so as to airtightly cover the opening thereof. and the inside of the tire casing).

18a is formed. Reference numeral 19 denotes a metal cylindrical bellows which is a response member and is disposed inside the holding case 17. A flange portion 19a at one end of the bellows is sandwiched between the end face of the holding case 17 and the cover 18. The end of the valve pipe 4 on the tire casing side is electrically insulated from the valve pipe 4 and is integrally connected to the metal cover 18. . The bellows 19 is sealed with air at a predetermined pressure, which serves as a reference for detecting the air pressure inside the tire casing.Therefore, the bellows 19 is designed such that its axial dimension is displaced in accordance with the magnitude of the air pressure inside the tire casing. In this case, a predetermined gap (f) is formed between the displacement side end surface 19b of the bellows 19 and the base end side end surface of the valve pipe 4 when the air pressure in the tire casing is normal. A movable contact 20 (corresponding to the contact portion in the embodiment of the present invention) and a fixed contact 21 are provided on the displacement side end surface 19b of the bellows 19 and the base end side end surface of the valve pipe 4, respectively. In this case, the distance between the movable contact 20 and the fixed contact 21 is determined by moving the bellows 19 near and far with respect to the valve pipe 4 by screwing the holding case 17 forward and backward. Reference numeral 22 denotes a metal contact member fixed to the center of the outside of the cover 18, and its tip side is provided in pressure contact with the tire wheel 1 by its own spring force. As a result of providing the contact member 22 in this way, the movable contact 20
and the tire wheel 1 are metal bellows 1, respectively.
9. Electrical connection is made via the cover 18 and the contact member 22. In addition, the bellows 19. The movable contact 20 and the fixed contact 21 constitute a two-end R-shaped pressure detection means 23 according to the present invention, and the tire wheel 1 is used as one terminal of the pressure detection means 23. and the valve pipe 4 is used as the other terminal.

24 is a DC power supply whose negative terminal is grounded, and whose positive terminal is connected to the lead wire 13a via a load 25. - The load 25 is constituted by, for example, a transmitter or other signal transmission means, and is configured to generate a transmission signal when energized and transmit it to a receiving device installed in the vehicle. Furthermore, Figure 2 is
- This shows the electrical connection state of the load 25, one end of which is connected to the positive terminal of the DC power supply 24, and the other end connected to the fixed contact 21 via the terminal 13 and the valve pipe 4. The movable contact 20 is also grounded via the bellows 19, the tire wheel 1, etc. As understood from FIG. 2, the movable contact 20 and the fixed contact 21 form a power switch B for the load 25.

According to the above configuration, when the air pressure inside the tire casing is in a normal state and when the displacement of the axial dimension of the bellows 19 is small (when the amount of low air pressure inside the tire casing is relatively small), The lII movable contact 20 and the fixed contact 21 are maintained in a spaced apart state. In this state, when the air pressure inside the tire casing abnormally decreases and the axial dimension of the bellows 19 displaces by more than a predetermined amount, the bellows 19 comes into contact with either the movable contact 20 or the fixed contact 21, and the gap between the valve pipe 4 and the tire wheel 1 increases. is in an electrically conductive state, in other words, the power switch B shown in FIG. 2 is turned on, and the negative 6:r 25 is energized. And in this way negative (,:j 25
When the load is energized, the load 25 generates a transmission signal and sends it to the receiving device installed in the city as mentioned earlier, causing the tire pressure inside the car to drop abnormally. You can know what happened. The air pressure when the movable contact 20 contacts the fixed contact 21 is determined by the pressure of the sealed air in the bellows 19, but the distance between the movable contact 20 and the fixed contact 21 is determined by screwing the holding case 17 back and forth. It can be finely adjusted by :Jn u+.

As described above, this embodiment skillfully utilizes the fact that the valve pipe 4 of the tire wheel 1 and the tire valve 2 is made of metal, and the pressure detection means 23 for detecting air pressure, the holding case 17, etc. Since the seal is placed inside the tire casing, there is no need for a separate, strict seal structure as in the past, making it possible to achieve smaller size and lower costs, as well as making installation work easier. It is. Although the pressure detection means 23 is provided in the tire casing in this way, the pressure detection means 23 is
Since the detection signals from both terminals of 3 can be obtained from between the tire wheel 1 and the valve pipe 4 which are exposed to the outside, there is no need for a special structure for extracting the detection signals, which also reduces the size and cost. It is possible to reduce this. Note that the bushing 3 provided as a seal structure is attached to the tire valve 2.
Since it is originally provided as part of the system, this will not cause a rise in costs. Furthermore, as mentioned above, since the air pressure detection part such as the pressure detection means 23 is disposed inside the tire casing, the environmental resistance of that part is improved and it is prevented from being damaged by external forces. , overall reliability will improve. Moreover, since only the terminal is exposed outside the tire wheel 1, the appearance does not deteriorate. Furthermore, the space in which the bellows 19 is arranged (the space formed by the holding case 17 and the cover 18) has small holes 17b and 18.
The structure is connected to the inside of the tire casing through a, and has a damper effect to attenuate sudden changes in air pressure inside the tire casing, so there is no possibility that the bellows 19 will operate through a due to instantaneous air pressure groaning. , reliability can be improved from this aspect as well.

In the above embodiment, the pressure detection means 23 is connected to the bellows 1.
9, an nJ movable contact 20, and a fixed contact 21), for example, it may be constructed by combining a bellows 19 and a two-terminal pressure sensor such as a strain gauge.

Further, the bellows 19 is not necessarily necessary, and it is sufficient to provide a two-terminal pressure detection means capable of detecting the air pressure inside the tire casing.

As is clear from the explanation below, since the pressure detection means, which is the air pressure detection part of vehicle tires, is provided inside the tire casing, a special sealing structure is not required, and the overall Miniaturization, cost reduction, and installation can improve work efficiency.In addition, the risk of damage due to external forces is eliminated, and environmental resistance can be improved, leading to improved reliability. This has an excellent effect in that it can be expected to improve the appearance and also improve the appearance.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an enlarged longitudinal sectional view, and FIG. 2 is a diagram showing an electrical connection state. In the figure, 1 is a tire wheel, 2 is a tire valve, 3 is a bushing, 4 is a valve pipe, 5 is an inner valve, 17 is a holding case, 18 is a cover, 17a, 18a are small holes, 19 is a bellows (response part +A ), 20 is a movable contact (contact part), 21 is a fixed contact 1-122 is a contact member, 23 is a pressure detection means, and 25 is a load. Applicant Tokai Rika Denki Seisakusho Co., Ltd. 1 Tire Wheel] Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. An air pressure detection device for a vehicle tire equipped with a metal tire wheel and a tire valve having an electrically insulated metal valve pipe, the tire casing being disposed within the tire casing. A two-terminal pressure detection means is provided which generates a detection signal depending on the magnitude of the air pressure inside the vehicle, one terminal of the pressure detection means is the tire wheel, and the other terminal is the valve pipe. Air pressure detection device for vehicle tires. 2. The pressure detection means is characterized in that it has a responsive member that is displaced depending on the magnitude of the air pressure within the tire casing, and is configured to generate a detection signal in accordance with the displacement of the responsive member. A vehicle tire air pressure detection device according to claim 1. 3. The response member is constituted by a bellows that is displaced according to the magnitude of the air pressure within the tire casing, and the pressure detection means is electrically connected to the tire wheel within the tire casing, and the pressure detecting means is electrically connected to the tire wheel within the tire casing, and when the bellows is displaced by a predetermined amount or more. The air pressure detection device for a vehicle tire according to claim 2, characterized in that the device includes a contact portion that sometimes comes into contact with a valve pipe.