JP4980979B2 - Shaft seal structure of gear reducer - Google Patents

Description

  The present invention relates to a shaft seal portion structure of a gear reducer.

As a conventional technique, there is a shaft seal structure of a gear reducer using a ball bearing 50 as shown in FIG.
FIG. 4 is a cross-sectional view of a main part of a shaft seal structure of a gear reducer using a conventional ball bearing.

However, when the ball bearing 50 is used as in Patent Document 1, it cannot cope with a relatively large load and, in particular, cannot cope with an axial load, so that there is a problem that the application is limited.
JP 2007-46653 A

  Therefore, it is conceivable to use a tapered bearing to cope with such a problem. According to the taper bearing, it is possible to cope with a larger load than that of the ball bearing, and in particular, an axial load.

However, instead of the conventional ball bearing 50 shown in FIG. Hereinafter, for the convenience of explanation, the above problems will be described with reference to FIGS. 3A and 3B showing an embodiment of the present invention.
When the gear reduction mechanism built into the gear reducer rotates, the lubricating oil enclosed inside is agitated, and a large amount of lubricating oil with pressure is sealed from the side closer to the outer race of the tapered bearing. Come in. When a large amount of lubricating oil having this pressure flows directly into the shaft seal structure, a large amount of lubricant leaks from the shaft seal structure. Therefore, in order to prevent this, between the filter 38 and the taper bearing 34, In addition, a pressure reduction wall 26a formed by extending a part of the gear case radially inward is provided. By causing the lubricating oil to collide with the pressure reduction wall 26a, the pressure is reduced and the pressure reduction wall 26a is collided. The lubricated oil is returned to the gear reduction mechanism by returning it again.
However, if only the tapered bearing 34 is used instead of the conventional ball bearing 50, the gap T between the side surface of the pressure reducing wall 26a and the side surface of the inner race of the outer race 34a of the tapered bearing 34 and the pressure reducing wall The gap Δ between the rotary shaft 26a and the rotation shaft is in a relation Δ≈T, and there is a problem that the lubricating oil colliding with the pressure reduction wall 26a hardly returns to the gear reduction mechanism.

By the way, as shown in FIG. 3B, the auxiliary convex portion 27 provided at the end portion of the pressure reducing wall 26a determines the gap T between the tapered bearing 34 and the inner race 34b. In general, tapered bearings handle larger loads and axial loads than ball bearings, but if the gap T is set narrower, the bearings circulate against the lubricating oil that has entered the pressure reducing wall from the tapered bearings. A path is not formed, and as a result, the reflux of the lubricating oil is hindered.
Moreover, if the said clearance gap T is small, as a result of the recirculation | reflux of lubricating oil being prevented, the cooling effect of lubricating oil will also fall. Then, the lubricating oil that has passed through the tapered bearing portion greatly reduces the viscosity of the lubricating oil due to the temperature rise due to the rolling resistance of the tapered bearing, and as a result, the oil film forming force between the inner race and the outer race of the tapered bearing is hindered. There is a possibility that seizure or the like due to metal contact is likely to occur.
Furthermore, if the thickness t of the pressure reduction wall is increased in the axial direction, there is also a potential problem that the compactness is lacking.
Accordingly, an object of the present invention is to solve the above-described conventional problems from the viewpoint of reliably feeding a relatively small amount of lubricating oil into the shaft seal structure and allowing it to return.

According to the present invention, a gear reduction mechanism is incorporated in a gear box, a lubricating oil for lubricating the gear reduction mechanism is enclosed in the gear box, a rotation shaft of the gear reduction mechanism is supported by a taper bearing, and the rotation shaft In the shaft seal part structure of the gear reducer that seals the leakage of lubricant from the oil seal,
The shaft seal structure includes the oil seal, a filter that filters the lubricating oil, and a pressure reduction wall that opposes the outer peripheral surface of the rotating shaft via a gap and reduces the pressure of the lubricating oil,
An auxiliary convex portion is formed between the side surface of the pressure reducing wall and the side surface of the outer race of the tapered bearing,
A gap T is provided between the side surface of the pressure reducing wall and the side surface of the inner race of the tapered bearing,
A gap Δ is formed between the inner peripheral surface of the pressure reduction wall and the rotating shaft,
The relationship between the gap Δ and the gap T is T> Δ,
The above problem has been solved by the shaft seal structure of the gear reducer.

  According to the present invention, since a relatively small amount of lubricating oil with reduced pressure is reliably delivered to the shaft sealing structure and refluxed, the heat generation of the lubricating oil is suppressed and the shaft sealing structure Appropriate lubrication can be achieved.

Hereinafter, the shaft seal structure of the gear reducer of the present invention will be described with reference to FIGS.
FIG. 1 is a front view including a partial cross section of the geared motor of the present invention. FIG. 2 is a side view including a partial cross section of the geared motor shown in FIG. 3A is an enlarged cross-sectional view of part A in FIG. 2, and FIG. 3B is an enlarged cross-sectional view of part B in FIG.

  First, the outline of the geared motor of the present invention will be described. As shown in FIG. 1, the geared motor 10 includes a motor unit 12 and a reduction gear unit 14, and the motor unit 12 and the reduction gear unit 14 are connected to a later-described load-side bearing bracket 16 of the motor unit 12. Are connected.

  As shown in FIG. 1, the motor unit 12 includes a motor shaft 18 that is rotatably supported at both ends, and a frame 20. A load side bearing bracket 16 that supports the load side of the motor shaft 18 via a load side bearing 22 is attached to one end of the frame 20, and although not shown, the other end of the frame 20 is on the side opposite to the load side of the motor shaft 18. An anti-load-side bearing bracket (not shown) that supports the non-load-side bearing via an anti-load-side bearing (not shown) is attached.

  In addition, the load side of the motor shaft 18 extends through the load side bearing 22, and a worm 24 is formed on the outer periphery of the extended portion. The worm 24 is located in a later-described gear case 26 of the speed reducer unit 14 and meshes with a later-described worm wheel 28 built in the gear case 26 of the speed reducer unit 14. Therefore, the motor shaft 18 has a function as an input shaft of the reduction gear unit 14.

  As shown in FIGS. 1 and 2, the speed reducer portion 14 includes a gear case 26 and a bearing bracket 26 ′ attached to the load side bearing bracket 16 of the motor portion 12, and the load side bearing bracket 16, the gear case 26, and the bearing bracket 26. A gear box 30 is configured by 'and. As shown in FIG. 2, the bearing bracket 26 'is detachably attached to the gear case 26 with bolts. A worm wheel 28 that meshes with the worm 24 and an output shaft (rotary shaft) 32 connected to the worm wheel 28 are incorporated in the gear box 30. Both end portions of the output shaft 32 are rotatably mounted by tapered bearings 34 and 34 'incorporated in the gear case 26 and the bearing bracket 26', respectively.

  The worm 24 and the worm wheel 28 constitute a gear reduction mechanism. The gear box 30 is filled with lubricating oil for lubricating a gear reduction mechanism constituted by the worm 24 and the worm wheel 28.

  As shown in FIGS. 1 and 2, the load-side bearing bracket 16 has the load side of the motor shaft 18 penetrated through the load-side bearing 22, and an opening on one end side of the frame 20 of the motor unit 12 and a reduction gear unit. The opening of the 14 gear cases 26 is closed, and the motor unit 12 and the speed reducer unit 14 are partitioned.

  Next, the shaft seal structure on one end side of the output shaft 32 will be described. In the following description, the embodiment of the present invention is described with respect to one end side of the output shaft 32. However, it is natural that the shaft seal structure of the present invention can also be implemented at the other end portion of the output shaft.

  As shown in FIG. 3A, an oil seal 36 for sealing leakage of lubricating oil in the gear box 30 is mounted between the gear case 26 and the outer peripheral surface of the output shaft 32. The oil seal 36 is disposed outside the tapered bearing 34. The oil seal 36 is used when the lubricating oil in the gear box 30 is stirred and scattered by the rotation of the worm 24 and the worm wheel 28. Is prevented from leaking outside through the tapered bearing 34.

  The oil seal 36 includes a lip 36a, a dust guard 36b, and a garter spring 36c. The lip 36a is pressed against the outer peripheral surface of the output shaft 32 by the tightening force of the garter spring 36c. The sliding part between the two maintains a proper contact.

A thin plate-like filter 38 is mounted adjacent to the oil seal 36 between the gear case 26 and the outer peripheral surface of the output shaft 32. The filter 38 is disposed on the tapered bearing 34 side of the oil seal 36, and this filter 38 filters the abrasion powder mixed in the lubricating oil which has been stirred and scattered.
The filter 38 is formed with a central hole having an inner diameter that is rotatably in close contact with the outer peripheral surface of the output shaft 32 on which the lip 20a of the oil seal 36 slides, and the outer peripheral surface is concentric with the central hole. It has a formed ring shape. That is, the filter 38 is closely fitted to the output shaft 32 in the center hole at the center thereof.

  The material of the filter 38 is a material that can filter fine particles such as abrasion powder and permeate the lubricating oil, and has a shape retaining property that does not deform even when subjected to the pressure of the lubricating oil. Although it may be sufficient, it is suitable to comprise with the nonwoven fabric which consists of a high density porous member.

  The filter 38 has a reinforcing plate 40 on the side surface on the oil seal 36 side. The reinforcing plate 40 has an outer diameter substantially the same as that of the filter 38, and a central hole having a larger inner diameter than the central hole of the filter 38 through which the output shaft 32 passes is formed at the center, and is a thin and rigid metal plate. It is made with. That is, the reinforcing plate 40 is loosely fitted to the output shaft 32.

  In the state where the filter 38 having the reinforcing plate 40 on one side surface is incorporated adjacent to the oil seal 36, an annular shape between the inner peripheral surface of the central hole of the reinforcing plate 40 and the outer peripheral surface of the output shaft 32 is provided. The gap 38 is shielded by the filter 38 so that the lubricating oil in the gear box 30 can flow between the oil seal 36 and the filter 38 through the portion of the filter 38 exposed in the annular gap portion. It has become.

In this embodiment, the filter 38 has the reinforcing plate 40 on one side surface, whereby deformation of the filter 38 due to the pressure of the lubricating oil can be suppressed, and the filter 38 can be made thin.
3A shows the filter 38 having the reinforcing plate 40 on the side surface on the oil seal 36 side, the embodiment is not limited to this, and the oil seal 36 side of the filter 38, The reinforcing plate 40 may be provided on at least one side surface of the tapered bearing 34 side.

  In this embodiment, from the tapered bearing 34 side to the oil seal 36 side, the filter 38 exposed in the annular gap portion between the inner peripheral surface of the central hole of the reinforcing plate 40 and the outer peripheral surface of the output shaft 32 is removed. Although only the portion has the lubricating oil distribution and filtering function, holes and slits may be formed in the reinforcing plate 40 as long as the rigidity is not impaired. As a result, the effective filtration area of the lubricating oil is increased, and clogging of the filter 38 can be made difficult to occur.

  A pressure reducing wall 26 a is formed between the filter 38 and the tapered bearing 34 by extending a part of the gear case 26 radially inward. The pressure reduction wall 26a is located adjacent to the filter 38 and closer to the tapered bearing 34 than the filter 38, and has a function of reducing the pressure of the lubricating oil that is stirred and scattered.

  If the width t of the pressure reduction wall 26a is made too thin, the strength to receive the pressure of the lubricating oil is insufficient, and if it is made too thick, the dimension increases in the axial direction and the overall structure of the speed reducer becomes large.

  Further, a gap Δ is provided between the inner peripheral surface of the pressure reduction wall 26 a and the outer peripheral surface of the output shaft 32. A gap T is provided between the pressure reduction wall 26 a and the inner race 34 b of the tapered bearing 34.

  If the value of the clearance T is too large, the size will increase in the axial direction and it will not be compact. Furthermore, since a large amount of lubricating oil will flow into the filter part of the oil seal, the lubricating oil flow rate reduction, flow velocity reduction, and pressure reduction effects Therefore, the cooling effect by the lubricating oil is not exhibited. On the other hand, if the gap T is too small, the reflux of the lubricating oil is hindered, so that the pressure at the bearing portion increases and the heat generation also increases. Further, since the oil flowing into the pressure reduction wall and the gap between the bearings does not flow out, it is considered that wear powder accumulates in the T portion.

  Therefore, regarding the relationship between the gap Δ and the gap T, T> Δ is set from the viewpoint of promoting the recirculation (outflow / inflow) action of the lubricating oil.

  In addition, although illustration is abbreviate | omitted, this invention is applicable also to the shaft seal part structure of a reduction gear type which does not have a motor.

The front view containing the partial cross section of the geared motor of this invention. The side view containing a partial cross section of the geared motor shown in FIG. (A) is an expanded sectional view of the A section of FIG. 2, (b) is an expanded sectional view of the B section of (a). Sectional drawing of the principal part of the reduction gear using the ball bearing of a prior art.

Explanation of symbols

26a: Pressure reduction wall 27: Auxiliary convex part 30: Gear box 32: Output shaft (rotating shaft)
34: Taper bearing 34a: Tapered bearing outer race 34b: Teter bearing inner race 36: Oil seal 38: Filter 40: Reinforcement plate

Claims (2)

A gear reduction mechanism is built in the gear box, and lubricating oil for lubricating the gear reduction mechanism is enclosed in the gear box, and the rotation shaft of the gear reduction mechanism is supported by a taper bearing. In the shaft seal part structure of the gear reducer that seals the leakage of oil with an oil seal,
The shaft seal structure includes the oil seal, a filter that filters the lubricating oil, and a pressure reduction wall that opposes the outer peripheral surface of the rotating shaft via a gap and reduces the pressure of the lubricating oil,
An auxiliary convex portion is formed between the side surface of the pressure reducing wall and the side surface of the outer race of the tapered bearing,
A gap T is provided between the side surface of the pressure reducing wall and the side surface of the inner race of the tapered bearing,
A gap Δ is formed between the inner peripheral surface of the pressure reduction wall and the rotating shaft,
The relationship between the gap Δ and the gap T is T> Δ,
Shaft seal structure of gear reducer.   The shaft seal portion structure of a gear reducer according to claim 1, further comprising a reinforcing plate on at least one side surface of the filter.

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