JP3162643B2 - Drive seal device for linear actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator (including a jack or the like) for moving an article or an object back and forth or moving up and down.
About.

[0002]

2. Description of the Related Art Conventionally, in a linear actuator, a drive unit for moving a linear operation shaft forward and backward is provided in a drive unit case, and a solid lubricating oil such as grease is sealed in the drive unit case. For example, a sealing member S mounted in the axial direction as shown in FIG. 2 is attached so that the lubricating oil does not leak from a penetration gap between the linear operating shaft that penetrates the case and moves forward and backward and the driving unit case. ing.

FIG. 2 is an enlarged sectional view of a main part of a sealing device of a linear actuator. A drive nut member N is externally fitted to a linear operation shaft A having a thread R formed on the outer periphery. And
The nut member N is rotatably mounted in the drive case H via a bearing B, and a solid lubricating oil G such as grease is sealed in the drive case H. The linear operation shaft A prevents rotation. When the drive nut member N is rotationally driven, the linear operation axis A moves in the axial direction with respect to the drive section case H, and the linear operation axis A
The actuated body attached to the tip of the robot moves forward and backward.

In order to prevent the lubricating oil sealed in the drive unit case H from leaking from the insertion gap δ between the drive unit case H and the linear operation shaft A, the outer peripheral surfaces of both ends of the drive nut member N and the outer periphery are formed. A seal member S such as an O-ring is provided in an axial lubricant leakage gap formed by the inner wall surface of the drive unit case facing the surface.
Are press-fitted.

[0005]

As described above, when the seal member S is inserted into the lubricating oil leakage gap in the axial direction, in order to prevent the seal member S from floating and separating in the radial direction and the axial direction, In order to form a seal member detachment prevention step D on the inner wall of the drive unit case H and form seal surfaces F on both outer peripheral surfaces of both ends of the drive nut member N, both ends of the drive nut member N are axially moved. Must be extended,
The axial length of the drive nut member N is increased, the thickness of the drive unit case for projecting the seal member detachment preventing step D is increased, and the shaft of the drive unit case is increased due to the increase in the length of the drive nut member N. Inevitably, the length in the direction is inevitably increased, which hinders downsizing of the drive unit case.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a method for forming a drive nut member which is in communication with an insertion gap between a drive case and a linear operating shaft. The above problem has been solved by a sealing device for press-fitting and fixing a sheet-shaped sealing member in a lubricating oil leakage gap in a thrust direction formed therebetween.

[0007]

Since the seal member is mounted in the lubricating oil leakage gap in the thrust direction, the seal member is not pinched between the both end surfaces of the drive nut member and the inner wall surface of the drive portion case and is not separated in the axial direction. Since the member is sheet-shaped, play is prevented by sticking it to the end surface of the drive nut member or the inner wall surface of the drive case, and lubricating oil sealed in the drive unit case causes the linear operation shaft and the drive unit case to be in contact with each other. There is no leakage from the penetration gap.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A jack shown in FIG. 1 will be described as an embodiment of a linear actuator. A drive unit case 2 into which a linear operating shaft 1 having a thread 1A engraved on its outer periphery is removably inserted is constituted by a case main body 2A having a concave cross section and a lid 2B. One drive unit is housed. The drive unit includes a worm gear 3 externally threadedly engaged with the linear operation shaft 1.
And a worm shaft 4 screwed to the worm gear 3. Both ends of the worm gear 3 in the axial direction are rotatably attached to the drive unit case 2 via bearings 5 and 5. The linear motion shaft 1 is prevented from rotating by known means (not shown). Therefore, when the external driving force is transmitted to the worm gear 3 via the worm shaft 4, the linear operation shaft 1 screwed to the worm gear 3 moves up and down in the axial direction without rotating, and the top of the linear operation shaft 1 Lifting or descending objects carried on the boat.

In the drive unit storage space in the drive unit case 2,
Solid lubricating oil G such as grease necessary for meshing transmission between the worm gear 3 and the worm shaft 4 and smooth rotation of the bearings 5 and 5 is sealed. The viscosity decreases due to the heat generation, and leaks from the penetrating screw gap (hereinafter simply referred to as a penetrating gap) δ between the linear operating shaft 1 and the drive unit case 2, so that the thrust direction communicating with the penetrating gap δ A sheet-like sealing member 7 is press-fitted into a lubricating oil leakage gap 6 (in a direction orthogonal to the direction of movement of the linear operating shaft 1), and at least one surface of the sealing member is stuck and fixed with an adhesive or the like to penetrate the lubricating oil. Prevents leakage into gap δ. The sheet-shaped seal member 6 is preferably formed of a polyester nonwoven fabric having a low coefficient of friction with heat resistance and abrasion resistance in an annular shape.

[0010]

According to the present invention, since the seal member 7 is press-fitted in the lubricating oil leakage gap 6 in the thrust direction, compared with the case where the seal member is mounted in the axial lubricating oil leakage gap in the prior art described above, Since there is no need to protrude the seal member detachment preventing step portion for fixing and holding the seal member on the inner wall of the drive unit case, it is possible to avoid thickening of the drive unit case, and to form the seal surface of the worm gear. Since it is not necessary to extend both ends in the axial direction, it is possible to avoid an increase in the axial length of the drive unit case, so that the drive unit case can be reduced in size, and further, since the seal member is sheet-shaped, Even if the leakage gap is small, it can be inserted, and the axial load applied to the linear operating shaft is distributed and loaded on the sheet-like surface to improve the service life of the sheet member. From The seating surface is increased to secure the fixing force of the sheet member, there is no risk of displacement, and since the seal member is mounted in the thrust direction, the load side seal member is pinched by the load applied to the linear operation shaft. It has excellent effects such as an increase in sealing action when pressed.

[Brief description of the drawings]

FIG. 1 is an enlarged front sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Linear operation shaft 2 Drive part case 3 Worm gear 4 Worm shaft 5 Bearing 6 Thrust direction lubricating oil leakage gap 7 Sheet-shaped seal member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B66F 3/00-3/46 F16J 15/00

Claims (1)

(57) [Claims] 1. A linear operating shaft which is prevented from rotating around an axis and is capable of moving forward and backward in the axial direction and has a thread formed on an outer periphery thereof, and a rotary drive nut member externally fitted to the operating shaft. ,
A drive unit case that rotatably mounts the nut member via a bearing and inserts the lubricating oil by penetrating the linear operation shaft so as to be able to move forward and backward. The sheet-like seal member is communicated with the insertion gap with the operating shaft and presses the sheet-like seal member into a thrust-direction lubricating oil leakage gap formed between both end surfaces of the drive nut member and the inner wall surface of the drive unit case facing the both end surfaces. A sealing device that is fitted and fixed.