JPH0556431B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an air vent plug for discharging air present in a hydraulic device to the outside, and particularly relates to an improvement in the air passage formed inside the plug.

Conventional technology and its problems If air is present in a hydraulic device, for example a hydraulic cylinder, the hydraulic cylinder will not operate smoothly due to the compressibility of air. If air gets inside the hydraulic cylinder, it must be removed. To vent the air, an air vent plug has conventionally been provided in a communication hole that communicates the inside and outside of a hydraulic device such as a hydraulic cylinder. A typical type of this air vent plug includes a male threaded part that is screwed into the male threaded part formed in the communication hole, and a valve part formed adjacent to the male threaded part. When the plug is tightened, this valve portion is pressed against a seat formed in the communication hole, and serves to close the communication hole in a fluid-tight manner. An axial hole and a radial hole are formed inside the air vent plug so as to communicate with each other in the axial and radial directions, and by loosening the plug, the valve part is separated from the seat part. In this state, these axial holes and radial holes cooperate with each other to form an air passageway through which the air present in the cylinder can escape to the outside.

Conventionally, in such air vent plugs,
An axial hole is formed spanning the male thread part and the valve part,
One end thereof was opened on the side opposite to the valve portion, while the valve portion side had a dead end shape, and a radial hole was formed in the valve portion so as to communicate with the dead end portion. However, if the radial hole is formed in the valve part in this way, when the valve part is pressed against the seat of the communication hole by tightening the plug, the radial hole will be affected by the compressive stress caused by the pressing. There was a problem that the valve part was easily deformed, and the valve part was also deformed, and the sealing performance between the valve part and the seat part was deteriorated.

On the other hand, it is conceivable to form the radial hole not in the valve part of the plug but in the externally threaded part having a larger diameter than the valve part. However, in this case, for example, with reference to the technology described in the above cited example, a radial hole is provided in the tip of the male threaded part where the first thread from the valve part side is provided. In this case, the compressive stress in the portion where the radial hole is provided is as large as the compressive stress in the valve portion, so it is still difficult to say that deformation of the radial hole and, by extension, deformation of the valve portion can be reliably prevented.

Solution The present invention has been made to solve these problems, and its gist is as follows:
In the air vent plug including a male threaded portion, a valve portion, an axial hole, and a radial hole as described above, the air vent plug is located on a side opposite to the valve portion from the first thread from the valve portion side of the male threaded portion. In the part, the radial hole is formed in the male threaded part, and a notch that opens on the valve part side is provided at the outer periphery of the male threaded part and in the part where the radial hole is formed. .

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

1 and 2, an air vent plug 10, which is an embodiment of the present invention, is shown in its entirety.
This air vent plug 10 is a shaft-shaped threaded member, and has a male threaded part 12 in the middle part, and has a hexagonal part 16 and a hose on one side with a shaft part 14 sandwiched therebetween as a tool engagement part for rotational operation. A joint portion 18 for connecting the two is formed, and a valve portion 20 is formed on the other side. The valve portion 20 is formed concentrically with the male threaded portion 12 and has a smaller diameter than the male threaded portion 12, and includes a tapered portion 22 at the distal end portion. Then, an axial hole 2 is formed along the axial center line of this plug 10.
4 is formed. The axial hole 24 opens to the outside at the joint portion 18 and is formed across the joint portion 18 , the hexagonal portion 16 , the shaft portion 14 and the male threaded portion 12 .
It has a dead end shape near the side end. A radial hole 26 is formed in communication with the dead end portion of this axial hole 24 . This radial hole 26 is a portion of the male threaded portion 12 that is closer to the valve portion 20 side, and is located closer to the valve portion 20 of the male threaded portion 12.
It is formed along the radial direction in a portion located on the opposite side of the valve portion 20 from the first thread from the side, and is opened at the outer peripheral portion of the male threaded portion 12 . In addition, in FIGS. 1 and 2, 27 indicates the top line of the first screw thread. A U-shaped notch 28 is provided in the portion of the male threaded portion 12 where the radial hole 26 opens, and as is clear from FIG. It is designed to form a surface,
The radial hole 26 opens at the bottom of this notch 28 .

The air vent plug 10 as described above penetrates the wall of the cylinder body 30 of the wheel cylinder in order to release air existing in the wheel cylinder of a hydraulic device such as a hydraulic cylinder, for example, a brake system of an automobile, to the outside. It is incorporated into a stepped communication hole 32 that communicates the inside and outside of the cylinder body 30. A female threaded portion 34 is formed in the large diameter portion of this communication hole 32, and the male threaded portion 12 of the plug 10 is screwed into this female threaded portion 34. Normally, the tip tapered portion 22 of the valve portion 20 is pressed against the tapered seat portion 36 formed in the stepped portion of the communication hole 32.
2 is kept fluid-tightly closed, but when hydraulic oil is sealed in the cylinder body 30, or for some reason after the hydraulic oil is sealed, the cylinder body 30
If air gets inside, remove air vent plug 1.
0 to separate the valve part 20 from the seat part 36, connect a hose to the joint part 18, and move the piston with the hose immersed in a predetermined oil container. Air existing in the form of bubbles in the oil, along with the hydraulic oil, flows through the gap between the valve part 20 and the seat part 36 into the notch 28, the radial hole 26,
The air is allowed to escape to the outside through the axial hole 24 and the hose, thereby making it possible to bleed the air inside the cylinder body 30.

When such air venting operation is completed, the plug 10 is screwed in by engaging the hexagonal part 16 with a spanner or the like, so that the tapered part 22 of the valve part 20 is pressed against the seat part 36 of the communication hole 32. At this time, the reaction force of the pressing is received by the male threaded portion 12 and the female threaded portion 34, and compressive stress in the axial direction acts on the plug 10. This compressive stress is greatest between the valve part 20, more precisely, the tapered part 22 and the crest line 27 of the first thread, and in the male thread part 12, from the crest line 27 to the shaft part 14 side. The closer you go, the smaller the number of threads becomes. In this case, the radial hole 26 is located in a portion of the male threaded portion 12 located on the opposite side of the valve portion 20 from the first thread from the valve portion 20 side, that is, in a portion where the compressive stress is smaller than that of the valve portion 20. Since the radial hole is formed in the male threaded portion 12 which has a larger diameter than the valve portion 20, deformation of the radial hole is reduced compared to the conventional case where the radial hole is formed in the valve portion where the compressive stress is greatest and the diameter is smaller than the male threaded portion. This can be prevented even more reliably. In addition, since the valve part 20 does not have a radial hole 26, the strength of the valve part 20 against compressive stress is increased, and the valve part 20 does not deform even when strongly tightened, and there is a gap between the valve part 20 and the seat part 36. Good sealing performance is maintained. Moreover, since the notch 28 that opens on the valve part 20 side is provided in the outer peripheral part of the male threaded part 12 and in the part where the radial hole 26 is formed, when the plug 10 is loosened, the inside of the cylinder body 30 is removed. Since the hydraulic oil can be easily guided to the radial hole 26 through the notch 28, even if the radial hole 26 is provided in the axially intermediate portion of the male threaded portion 12, the connection between the male threaded portion 12 and the female threaded portion 34 of the communication hole 32 is prevented. It is possible to suitably prevent the hydraulic oil in the cylinder body 30 from leaking between the cylinder bodies 30 and 30.

Although one embodiment of the present invention has been described above, this is literally an illustration, and the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art. The present invention is also effective not only for hydraulic cylinders such as wheel cylinders, but also for other hydraulic equipment.

Effects of the Invention As described above, the present invention has a male threaded portion,
An air vent that includes a valve part, an axial hole and a radial hole that serve as air vent passages, and is disposed in a communication hole that communicates the inside and outside of the hydraulic equipment to release air existing inside the hydraulic equipment to the outside. In the plug,
A radial hole is formed in the male thread part in a part located on the opposite side of the valve part from the first thread from the valve part side of the male thread part, and a radial hole is formed in the outer periphery of the male thread part. It is characterized by providing a notch that opens on the valve part side in the part where it is opened, thereby suitably preventing liquid leakage from between the male threaded part and the female threaded part of the communication hole. Therefore, deformation of the radial hole and, in turn, deformation of the valve portion can be more reliably prevented, and the communicating hole can be more reliably sealed. This prevents deformation of the radial hole and, by extension, deformation of the valve portion, making it possible to effectively seal the communication hole formed in the hydraulic device.

[Brief explanation of the drawing]

FIG. 1 is a front view of an air vent plug according to an embodiment of the present invention and a diagram showing the state in which the air vent plug is installed, and FIG. 2 is a perspective view of the air vent plug. FIG. 3 is a - sectional view in FIG. 1. 10: Air vent plug, 12: Male thread, 2
0: Valve part, 22: Tapered part, 24: Axial hole, 2
6: Radial hole, 27: (first thread) crest line, 28: Notch, 30: Cylinder body (hydraulic equipment), 32: Communication hole, 34: Female thread, 36: Seat.

Claims (1)

[Scope of Claims] 1. An air vent plug disposed in a communication hole that communicates the inside and outside of the hydraulic equipment in order to release the air present in the hydraulic equipment to the outside, the air vent plug being disposed in a communication hole that communicates the inside and outside of the hydraulic equipment, comprising: a male threaded portion that is screwed into a female threaded portion formed in the male threaded portion; and a male threaded portion formed adjacent to the male threaded portion and normally pressed against a seat portion formed in the communication hole to close the communication hole in a fluid-tight manner. a valve portion having a smaller diameter than the male threaded portion; and a valve portion that communicates with each other in the axial and radial directions of the air vent plug, and is present in the hydraulic equipment in a state where the valve portion is spaced apart from the seat portion. In an air vent plug including an axial hole and a radial hole that cooperate with each other to form an air passage for escaping air to the outside, In the part located on the opposite side,
The radial hole is formed in the male threaded portion, and a notch that opens on the valve portion side is provided on the outer periphery of the male threaded portion and in a portion where the radial hole is formed. Air vent plug for pressure equipment.