JPS6239561Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a negative pressure changeover switch, and particularly relates to a changeover switch that is easy to push and pull, has little negative pressure leakage, and is highly durable.

BACKGROUND ART Conventionally, a push button type negative pressure changeover switch has been widely used as an operating means for controlling a heater in an automobile because a negative pressure source can be easily obtained and the structure of the device is extremely simple.

This changeover switch is of a piston type and consists of one set of a piston and a cylinder. An "O" ring is fitted into each of the annular grooves near both ends of the piston, so that the piston can slide within the cylinder together with both "O" rings. On the other hand, the cylinder is provided with one negative pressure supply port (nipple) and at least one negative pressure output port (nipple) that opens at a position separated by a certain distance from the negative pressure supply port (nipple). As the "O" ring moves back and forth to the negative pressure output port position as the piston reciprocates,
The negative pressure supply port and the negative pressure output port are brought into communication or cut off. In this way, the diaphragm etc. connected to the negative pressure output port are operated by the negative pressure source connected to the negative pressure supply port, and various devices such as a heater control are controlled.

However, in the negative pressure changeover switch configured in this way, the piston is supported with respect to the cylinder only by the "O" ring, so the resistance force against the horizontal wobbling of the piston axis is weak, and therefore the negative pressure changeover switch is The drawback is that pressure leaks are likely to occur, and for this reason, when the "O" ring is fitted in a strongly compressed state to prevent negative pressure leaks, the frictional force between the piston and cylinder increases, making it difficult to push and pull the piston. This makes it difficult to control the equipment easily. Furthermore, the "O" ring that moves together with the piston is easily damaged by being scratched at the opening of the negative pressure output port, and therefore, there is a drawback that airtightness cannot be stably maintained.

The present invention has been developed in view of the above circumstances, and its gist is that, in a negative pressure changeover switch consisting of a cylinder and a piston, a piston into which the piston is inserted is arranged inside the cylinder. The stepped hole is composed of a small diameter part located on the operating side and a large diameter part opened to the atmosphere, and the small diameter part is provided with a first port connected to a negative pressure source, and the large diameter part is is provided with a second port connected to the side operated by negative pressure, and a first sealing member for sealing against the piston on the inner surface of the cylinder located on the piston operation side from the first port. At the same time, a second seal member is attached to the outer peripheral surface of the end of the piston that is reciprocated within the large diameter portion of the cylinder to provide a seal between the large diameter portion and the piston. There is a particular thing.

Thus, according to the present invention, the first sealing member is fitted and fixed to the small diameter portion of the cylinder,
Since the piston is in sliding contact with the inner part of the first sealing member, the contact area of the piston with the first sealing member is small, and therefore the pushing and pulling operations of the piston are easy, reducing sliding resistance. This results in improved wear resistance. In addition, since the first sealing member does not slide over the opening of the negative pressure supply port or the negative pressure output port, it will not be scratched or damaged by these, and therefore, negative pressure leakage will be prevented. There are few
This makes it highly durable. Furthermore, since the cylinder is equipped with a stepped section, the movement range of the piston is reliably defined, and it provides excellent negative pressure that can be applied to pushbutton switches to enable accurate ON-OFF operation. A transfer switch may be provided.

Hereinafter, one embodiment of the negative pressure changeover switch according to the present invention will be described in more detail based on the drawings.

First, in Fig. 1, 2 is a negative pressure changeover switch as a push-button changeover switch for controlling a heater in an automobile, and the cylinder 4 and piston 6 are molded from synthetic resin such as polyacetal.
It consists of.

Inside this cylinder 4, a hole (stepped hole) consisting of a large diameter part 10 and a small diameter part 12 is formed on both sides of the stepped part 8, and a left end of the small diameter part 12 in FIG. A small ring-shaped protrusion 14 facing inward is formed near this portion, and a part of a groove 18 into which an "O" ring 16 (first sealing member) can be fitted is formed further to the left of the ring-shaped small protrusion 14, and further to the left of this portion has a deeper cut 22 into which the plate 20 can be driven.
is formed. Therefore, when the plate 20 is driven into the cut portion 22, a groove 18 in which the "O" ring 16 can be accommodated is formed.

Further, in the small diameter portion 12, a nipple-shaped first port 26 connected to a negative pressure source 24 is provided in the concave groove 1.
8 is provided so as to open toward the stepped portion 8 side. That is, the "O" ring 16 is connected to the first port 2.
It is arranged on the piston operation side (left side in Figure 1) than 6. Further, the large diameter portion 10 is provided with a nipple-shaped second port 30 that is connected to a diaphragm 28 or the like that is operated by negative pressure.

On the other hand, the piston 6 consists of a head 32 and a shaft 34, the head 32 having a smaller diameter than the large diameter part 10 of the cylinder 4 and larger than the small diameter part 12, and an "O" ring 36 (second seal). The shaft portion 34 has a diameter smaller than the small diameter portion 12 of the cylinder 4 by a predetermined percentage, and has a notch portion 35 near its end for engagement.
is formed. Therefore, the “O” ring 1
6 can be brought into sliding contact with the circumferential surface of the shaft portion 34 of the piston 6 at its inner portion, while the “O” ring 36 can be brought into sliding contact with the large diameter portion 10 of the cylinder 4 at its outside portion, and when The cylinder 4 and piston 6 are also configured to be kept airtight.

Note that when the head 32 of the piston 6 is in contact with the stepped portion 8, that is, in the state shown in FIG. It is arranged to be located to the right of the O'' ring 36 (closer to the open end of the large diameter portion 10).

In the negative pressure changeover switch 2 configured in this way, as shown in FIG. Since it is connected, the diaphragm 28 is in an OFF state. However, as shown in FIG. 2, when the piston 6 is pushed to the right (pushing state), the second port 30 communicates with the first port 26 connected to the negative pressure source 24, so the diaphragm 28 A negative pressure acts on the diaphragm 28, and the diaphragm 28 is turned on. Thus, by putting the piston 6 in the pushing or pulling state, the diaphragm 2
8 can be turned on or off, and therefore the hot air on-off valve etc. driven by the diaphragm 28 are opened and closed, and the heater control itself is controlled.

In the negative pressure changeover switch 2 having such a structure and operation, an "O" ring 16, which is a first sealing member, is fitted into the small diameter portion 12 of the cylinder 4, and the inner part of this "O" ring 16 Since the shaft portion 34 of the piston 6 is in sliding contact with the inner surface of the cylinder, the contact area where frictional resistance is generated is narrower than the conventional "O" ring in which the outer part of the ring is in sliding contact with the inner surface of the cylinder. The force required to push and pull 6 is small, making the operation easier.

Further, the “O” ring 16 is connected to the shaft portion 3 of the piston 6.
However, since the shaft portion 34 is cylindrical and does not have a port opening or the like, the "O" ring 16 will not be scratched or damaged by the port opening or the like. Note that the sliding contact portion of the shaft portion 34 is drawn in advance and has a zero taper.
Moreover, since the surface precision is smoothed to ▽▽25Z, the "O" ring 16 is highly durable, and the switch 2 has reduced sliding resistance and improved wear resistance.

Further, since the "O" ring 16 is attached to the inner surface of the cylinder 4, a ring-shaped protrusion 14 that prevents the piston 6 from moving in the radial direction can be advantageously formed on the inner surface of the cylinder, thereby preventing the piston 6 from lateral wobbling. It is possible to effectively prevent this and improve its operability.
This also contributes to improved sealing performance.

Furthermore, since the cylinder 4 is provided with a stepped portion 8 as a stopper, the range of push/pull movement of the piston 6 is reliably defined, and therefore the relative relationship between the second port 30 and the "O" ring 36 is fixed. This provides excellent effects such as the position being determined and the diaphragm 28 being able to be turned ON and OFF accurately.

In addition, in the above-mentioned embodiment, an example was shown in which the negative pressure changeover switch was applied to the heater control of an automobile, but the present invention is not limited to this in any way, and can be applied to vehicles other than automobiles. It is also possible to apply it to equipment other than heater control. Furthermore, the material of the negative pressure selector switch is not only polyacetal, but also
Other suitable synthetic resins and even other materials may be used.

In addition, it goes without saying that various modifications and improvements can be made to the present invention based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the negative pressure changeover switch according to the present invention in the OFF state, and FIG. 2 is a sectional view showing the same in the ON state. 2...Negative pressure switch, 4...Cylinder, 6
...Piston, 8...Stepped part, 10...Large diameter part,
12...Small diameter part, 16..."O" ring, 24...
...Negative pressure source, 26...First port, 30...Second port, 36..."O" ring.

Claims (1)

[Scope of utility model registration request] In a negative pressure switching switch consisting of a cylinder and a piston, the inside of the cylinder is formed as a stepped hole consisting of a small diameter part located on the piston operation side into which the piston is inserted and a large diameter part opened to the atmosphere. The part is provided with a first port connected to a negative pressure source, and the large diameter part is provided with a second port connected to the side operated by the negative pressure, A first seal member for sealing the piston is attached to the inner surface of the cylinder located on the piston operation side, and a second seal is attached to the outer circumferential surface of the end of the piston that is reciprocated within the large diameter portion of the cylinder. 1. A negative pressure changeover switch characterized in that a member is attached to perform a seal between the large diameter portion and the piston.