JP2579380Y2 - Ball screw sealing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball screw sealing device.

[0002]

2. Description of the Related Art In a ball screw, a plurality of balls are arranged between a spiral groove provided on an outer peripheral surface of a screw shaft and a spiral groove provided on an inner peripheral surface of a ball nut, and the rotational power of the screw shaft is supplied to the ball screw. In order to prevent leakage of the lubricant filled in the ball nut and intrusion of foreign matter from the outside, as shown in FIG. A ring-shaped labyrinth seal member 25 having a projection 25a fitted into the spiral groove 21a is
2 at both ends. Seal member 25
Is fixed by a set screw 29 or the like screwed into the screw hole 22b of the ball nut 22.

[0003]

In the above-mentioned sealing device, the sealing member 25 is fitted to the screw shaft 21 and then fixed with a set screw 29 screwed to the ball nut 22, and the projection 25a and the spiral groove are formed. The fitting clearance between the seal member 25a and the screw shaft 21 depends on the dimensional relationship between the seal member 25 and the screw shaft 21. For this reason, a large clearance is generated between the protrusion 25a and the spiral groove 21a, and the sealing performance may be insufficient depending on the use conditions.

An object of the present invention is to improve the sealing performance of a sealing device for a ball screw.

[0005]

According to the first aspect of the present invention, a ring-shaped seal member is divided into a plurality of portions in the axial direction, and the divided portions are elastically pressed in the inner diameter direction to thereby provide a seal member. The clearance between the projection and the spiral groove of the screw shaft is reduced to zero or less, and an auxiliary ring is mounted on the inner side of the ball nut with respect to the seal member.

According to the second aspect of the present invention, the seal member is divided into a plurality of axial slits from the end face facing the outside of the ball nut to an intermediate portion, and the divided part is elastically pressed toward the inner diameter side. By doing so, the fitting clearance between the projection and the spiral groove is set to zero or less.

[0007] Claim 1 is that the seal member itself is divided, and Claim 2 is that the seal member is partially divided. The state where the fitting clearance is equal to or less than zero means a state where the fitting clearance is zero or a state having a margin (minus clearance).

[0008]

The projection can be brought into close contact with the spiral groove of the screw shaft by dividing the seal member into a plurality of portions and pressing the divided portions in the radial direction.

[0009] Foreign matter adhering to the surface of the spiral groove of the screw shaft,
It is scraped off by the dividing surface of the seal member. The unsplit ring portion of the auxiliary ring or seal member prevents the scraped foreign material from attempting to penetrate the ball nut through the split surface.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a plurality of balls 3 are arranged between a spiral groove 1a provided on an outer peripheral surface of a screw shaft 1 and a spiral groove 2a provided on an inner peripheral surface of a ball nut 2. . When the screw shaft 1 rotates, the rotational power is transmitted to the ball nut 2 via the ball 3, and the ball nut 2 moves in the axial direction. A seal member 5 and an auxiliary ring 6 are mounted on both ends of the ball nut 2.

As shown in FIG. 2, the sealing member 5 is formed by molding a resin material or a rubber material such as fluoro rubber into a ring shape, and dividing the ring material at three circumferentially equally spaced positions in the axial direction. It was done. The seal member 5 has a protrusion 5 a protruding in the inner diameter direction, and the protrusion 5 a has a shape and dimensions corresponding to the spiral groove 1 a of the screw shaft 1.

Each of the three divided portions of the seal member 5 is pressed in the radial direction by a ball plunger 8 screwed into the screw hole 2b of the ball nut 2. Therefore, as shown in FIG. 1b in an enlarged manner, the fitting clearance between the projection 5a and the spiral groove 1a is zero or slightly negative (in a state having a margin). It should be noted that there is a slight gap between the divided portions of the seal member 5. As described above, since the protrusion 5a is in close contact with the spiral groove 1a, the lubricant in the ball nut 2 is hardly leaked to the outside, and foreign matter is hardly intruded from the outside.
Further, since each of the divided surfaces 5b of the seal member 5 scrapes off the foreign matter adhering to the surface of the spiral groove 1a, the sealing performance is extremely high as compared with the conventional one. The auxiliary ring 6 prevents the scraped foreign substance from trying to enter the ball nut 2 through the dividing surface 5b.

In the embodiment shown in FIGS. 3 and 4, the portion from the end face 5c facing the outside of the ball nut 2 to the middle of the seal member 5 is divided by a plurality of axial slits 5d and divided. The portion is elastically pressed to the inner diameter side by the garter spring 10. The same operation and effect as those of the above-described sealing device can be obtained. In this embodiment, foreign matter scraped off from the surface of the spiral groove 1a by the divided surfaces 5b of the seal member 5 is prevented from entering the ball nut 2 by the undivided ring portion 5e of the seal member 5. Is done. Therefore, the above-described auxiliary ring 6
Is not located.

The configuration shown in FIG. 1 and the configuration shown in FIG. 3 may be used together.

[0016]

According to the present invention, according to the present invention, the projecting portion of the sealing member is brought into close contact with the spiral groove of the screw shaft with a fitting clearance of zero or less,
In addition, since the foreign matter adhering to the surface of the spiral groove is scraped off by the divided surface of the seal member, the sealability can be significantly improved as compared with the conventional one.

[Brief description of the drawings]

FIG. 1 is a sectional view (FIG. A) showing an embodiment of the present invention, and a partially enlarged sectional view (FIG. B) in FIG.

FIG. 2 is a front view (FIG. A) and a side view (FIG. B) showing a seal member in FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a front view (FIG. A) and a side view (FIG. B) showing the seal member in FIG. 3;

FIG. 5 is a sectional view showing a conventional sealing device.

[Explanation of symbols]

 Reference Signs List 1 screw shaft 1a spiral groove 2 ball nut 2a spiral groove 5 sealing member 5a protrusion 5d slit 6 auxiliary ring 8 ball plunger 10 garter spring

Continuation of the front page (56) References Japanese Utility Model Sho-59-172812 (JP, U) Japanese Utility Model Sho 58-178553 (JP, U) Japanese Utility Model 2-91253 (JP, U) Japanese Utility Model Utility Model 1-78772 (JP) , U) Jikken 38-7725 (JP, Y1) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 25/24

Claims (2)

(57) [Scope of request for utility model registration] 1. A ring-shaped sealing member having a projection fitted into a spiral groove of a screw shaft is mounted on an end of a ball nut to seal the inside of the ball nut. Along with splitting in the axial direction, by pressing the split portion in the inner diameter direction, the fitting clearance between the protrusion and the spiral groove is reduced to zero or less, and on the inner side of the ball nut than the seal member. A ball screw sealing device, wherein an auxiliary ring is mounted on the ball screw. 2. A method of mounting a ring-shaped sealing member having a projection fitted into a spiral groove of a screw shaft on an end of a ball nut to seal the inside of the ball nut, wherein the sealing member includes a ball nut. By dividing a portion from the end face facing outward to the middle portion by a plurality of axial slits and pressing the divided portion toward the inner diameter side, the fitting clearance between the protrusion and the spiral groove is reduced to zero. A ball screw sealing device characterized by the following.