JPS5931961Y2 - Shaft seal structure of reciprocating actuator - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a shaft seal structure suitable for application to a reciprocating actuator such as a piston type or diaphragm type actuator for operating a control valve or the like.

Many reciprocating drive type actuators are equipped with a substantially cylindrical housing, and a drive shaft that interlocks with a piston projects in the axial direction of the housing.

This drive shaft performs coaxial reciprocating motion, and in some cases is induced to swing motion following the motion trajectory of the operating side.

Since the drive shaft is a reciprocating type, the protrusion hole through which the drive shaft penetrates becomes a breathing hole for moving the internal piston, etc. Otherwise, there is a certain gap around the drive shaft so as not to restrict the complex movement of the drive shaft. It is requested that a

In this case, if dust, rainwater, insects, etc. enter through the gap, accidents such as malfunctions are likely to occur, so various proposals have been made for dust seal structures.

For example, the drive shaft between the actuator and the operating side such as a control valve is covered with a dustproof case, but this type of seal structure is difficult to assemble.
This had the disadvantage of high costs.

There is also a seal structure that uses a bellows body and airtightly fixes the opening at one end around the drive shaft and the opening at the other end to the protrusion of the actuator, but in this case, the length of the bellows body This is approximately equivalent to the stroke of the actuator, which poses a major obstacle to miniaturizing the entire device.

Furthermore, if we focus only on the simple seal structure,
A seal has been proposed for use in a continuous vulcanization device for rubber insulated wires, as seen in Japanese Patent No. 9-5796.

This is equipped with a relatively large number of sheets in order to strongly seal electric wires moving in one direction, and is intended to achieve sealing performance as tight as possible to obtain a pressure difference before and after the seal.

In such a case, the size of the center hole of the seal sheet is not so small, and therefore tightness cannot be achieved unless the seal sheet contacts the electric wire at an angle close to right angles.

Therefore, when trying to use this in a reciprocating drive type actuator like the present invention, it cannot function as a breathing hole at all, and the shaft cannot be driven reciprocatingly, and if the shaft is driven in the opposite direction, The contact angle of the seal sheet to the shaft cannot be maintained, and the sheet may instead become entangled, leading to a risk of malfunction.

The present invention was developed in view of the above-mentioned drawbacks of the conventional technology, and is formed into a ring shape with a sufficiently small center hole.
A relatively small number of sheets with slits arranged radially around the small center hole are stacked together so that the slits of each sheet do not overlap with the slits of adjacent sheets, and this sheet is formed to have a sufficiently large diameter. Installation is easy due to the extremely simple structure of attaching the drive shaft through a sheet retainer that is forcibly bent to cover the drive shaft projection port, and passing the drive shaft through the small center hole of these sheets. It is possible to reliably close the gap, is suitable for downsizing, and is able to apply appropriate tension and shaft contact angle to the entire sealing material despite the large gap around the drive shaft. Therefore, the present invention provides a shaft seal structure for a reciprocating drive type actuator that can also prevent seat entrainment accidents.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the shaft seal structure according to the present invention, and FIG. 2 is a sectional view taken along the line II in FIG. 1.

In these figures, the reference numeral 1 denotes a flat plate-like mounting fixed to the outer wall surface of the reciprocating actuator 2 with screws. A drive shaft protrusion 3 having an inner diameter sufficiently larger than the outer diameter is bored.

In the above-mentioned installation, a relatively small number of sheets (5 sheets are used in this example) formed in a ring shape from a flexible material such as rubber are coaxially laminated on the inner surface of the base 1. The peripheral edge portion thereof is fixed by, for example, four setscrews 6 so as to close the drive shaft protrusion port 3.

As shown in FIG. 3, each sheet 5 has a small center hole 7 with a diameter sufficiently smaller than the outer diameter of the drive shaft 4, and around this small center hole 7, holes are distributed at approximately equal intervals in the circumferential direction. A plurality of slits 8 are formed radially.

In this case, each sheet 5 is arranged so that the slits 8 of adjacent sheets do not overlap each other, that is, the slits 8 of the 1st, 3.5th sheets 5 are at the position of the slit 8 shown by the solid line in FIG. This, and the second and fourth sheets 5
The slits 8 are stacked so as to be located at the position of the slit 8' indicated by the dotted line (the center of the adjacent solid line slits).

Then, on the periphery of each regularly stacked sheet 5, there are four screw mounting holes 9 equally distributed in the circumferential direction.
are formed coaxially.

For the above-mentioned installation, a ring-shaped sheet presser 10 is disposed on the outermost surface of the sheets 5 stacked on the base 1, and the sheet presser 10 uniformly presses the peripheral edge of each sheet 5. The installation is fixed to base 1.

For this reason, each setscrew 6 is inserted into a screw attachment hole drilled in the seat holder 10 and a screw attachment hole 9 in the seat 5, and is screwed into a screw hole 11 in the base 1.

Also, a hole 1 bored in the center of the sheet presser 10
2 has an inner diameter sufficiently larger than the outer diameter of the drive shaft 4, and the peripheral edge of the hole 12 is bent with a gentle curvature in the direction of the drive shaft protrusion 3 by drawing or the like.

Therefore, the center portion of each seat 5 is forcibly inserted into the drive shaft protrusion 3 as shown in FIG.

By doing so, it is possible to sharply bend the shaft contact piece of the sheet 5 from the projection opening 3 having a sufficiently large diameter, and at the same time, apply internal stress to the vicinity of the bending part to apply tension to the waist. can be strengthened.

In this state, the drive shaft 4 is inserted into the hole 12 of the sheet presser 10 and the small center hole 7 of the sheet 5, as shown in FIG.
The drive shaft is inserted through the drive shaft and protrudes to the outside from the drive shaft protrusion port 3.

At this time, the slits 8 of each sheet 5 expand according to the outer peripheral surface of the drive shaft 4 as shown in FIG. 2, creating a gap G.
This gap G is closed by the adjacent sheets 5 because it is provided so that the slits 8 of the adjacent sheets 5 do not overlap.

Moreover, since the center hole 7 of each sheet 5 is sufficiently smaller than the outer diameter of the drive shaft 4, it comes into contact with the outer circumferential surface of the shaft 4 and further expands, and continues into the sheet bent portion near the ejection opening 3. It is possible to apply a wide tension force around the center hole of the sheet.

Moreover, the contact angle of the seat 5 with respect to the shaft 4 at this time is
As shown in the figure, a moderate inclination of around 45° can be created, and the reciprocating movement of the shaft 4 combined with the tension of the sheet does not cause the sheet to be rolled up.

In the above embodiment, the seat 5 is attached to the base 1.
Although the present invention is not limited to this, it goes without saying that the laminated sheet may be directly fixed to the drive shaft protrusion of the actuator, and the base 1 may be omitted for attachment.

Also, if monobutyne dioxide (MoS2) powder is rubbed on both sides of each sheet 5 in advance, each sheet 5
This improves the slippage between the two and increases the close contact with the drive shaft 4.

As explained above, in the shaft seal structure of the reciprocating drive type actuator according to the present invention, the shaft protrusion opening for attaching the ring-shaped laminated sheet is formed sufficiently large so that the ring-shaped sheet is forcibly bent within the protrusion opening. Since the seat is mounted in pressure contact with a seat retainer, the tension of the waist portion of the seat exposed within the projection opening can be increased, and the seat can be faced at an appropriate angle with respect to the shaft 4.

In addition, since the center hole of the ring-shaped sheet is formed sufficiently small, the diameter of the hole is further enlarged when the shaft is inserted, and the tension near the center hole and the angle of contact with the shaft can be maintained at an appropriate level. .

Therefore, the portion of the ring-shaped sheet that faces the ejection opening and has a relatively large area spreads tension throughout the ring-shaped sheet, and despite its reciprocating motion, the sheet is rolled in. It is possible to provide an appropriate angle of inclination to prevent

Furthermore, since the number of stacked sheets is relatively small, it is possible to prevent the intrusion of dust, rainwater, insects, etc. while ensuring a gap that is sufficient for the reciprocating actuator to breathe.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line I-I in Fig. 1, Fig. 3 is a plan view of the seat, and Fig. 4 shows the state before the drive shaft is inserted. FIG. 1... Mounting on the base, 2... Actuator, 3... Drive shaft protrusion, 4...
Drive shaft, 5... Sheet, 7... Small center hole, 8... Slit, 10... Sheet holder.

Claims (1)

[Scope of utility model registration request] A reciprocating actuator, a drive shaft protruding from the actuator to the outside, a sufficiently large diameter drive shaft protrusion hole drilled in the actuator, and a small center hole sufficiently smaller than the outer diameter of the drive shaft. It consists of a ring-shaped sheet layer formed by laminating a relatively small number of sheets, and a sheet holder that is attached to forcibly bend this ring-shaped sheet layer into the ejection opening, and around the small center hole of each sheet. Radial slits are provided at approximately equal intervals, and each sheet is stacked so that the slits of adjacent sheets do not overlap, and by passing the drive shaft through the small center hole of these sheets, the small center hole is further enlarged. A shaft seal structure for a reciprocating drive type actuator, wherein the shaft seal structure provides an appropriate shaft contact angle and tension force to the entire unsupported portion of the sheet facing into the ejection opening, thereby preventing sheet entrainment. .