JP2012067899A - Step-up/reduction gear - Google Patents

Abstract

By increasing the number of rollers on the second shaft side that can mesh simultaneously with the spiral groove of the first shaft in a worm gear type speed reducer in which friction transmission between gear tooth surfaces is converted to roller rolling transmission, Reduces the load on each roller and enables downsizing.
A first shaft formed with a spiral groove and a second shaft having a roller rotatably supported by a plurality of pivots provided to protrude from a flange portion. The first shaft is formed by a pitch circle at the tip of the pivot. Is arranged near the center of the second axis so that the spiral groove meshes with the plurality of rollers.
[Selection] Figure 1

Description

  The present invention relates to a speed increasing / reducing gear that improves power transmission efficiency by converting power transmission accompanied by friction between tooth surfaces in a worm gear type speed reducer to roller rolling transmission.

  Conventionally, as this kind of speed increasing / decreasing device, a plurality of cam followers (rollers) provided radially on the outer periphery of the rotary table (second shaft), and a driven shaft (first shaft) arranged radially outside the cam follower A roller gear cam (spiral groove) formed on the shaft) is known (see, for example, Patent Document 1).

  However, in the method in which the above rollers are provided radially on the second axis, the first axis is arranged on the outer side in the radial direction of the roller, and the number of rollers that can mesh with the spiral groove of the first axis is the same. Since there are only about three, there are severe restrictions on the torque that can be transmitted, making it difficult to reduce the size of the speed reducer.

JP 2002-126958 A

The problem to be solved is that it is difficult to transmit a large torque because the number of rollers on the second shaft side that can mesh with the spiral groove of the first shaft is small.
The object of the present invention is to increase the speed of the second shaft to increase the number of rollers that can mesh simultaneously with the spiral groove of the first shaft, thereby reducing the load on each roller and obtaining the same output torque. It is to be able to reduce the size of the machine.

  In order to increase the number of rollers that can mesh simultaneously with the spiral groove of the first shaft, the speed increasing / decreasing device of the present invention is provided with a plurality of rollers parallel to the second shaft on the flange portion of the second shaft, and the pitch of the rollers The most important feature is that the first axis is arranged closer to the center of the second axis than the circle.

  That is, the speed increasing / decreasing device of the present invention includes a first shaft having a spiral groove and a second shaft having a plurality of rollers, the second shaft having a flange portion, and a plurality of shafts on the outer periphery of the flange portion. The pivot is provided so as to project from the flange portion, the roller is rotatably supported by the projecting portion of the pivot, the first shaft is disposed closer to the center of the second shaft than the tip pitch circle of the pivot, and the spiral groove Simultaneously mesh with some of the plurality of rollers at the same time.

In the speed increasing / decreasing device of the present invention, a roller supported by a plurality of pivots is provided on the outer periphery of the flange portion of the second shaft, and the first shaft is disposed closer to the center of the second shaft than the tip pitch circle of the pivot. The number of rollers that can mesh simultaneously with the spiral groove of the first shaft can be increased, the load on the rollers can be distributed accordingly, and a larger torque can be transmitted, thereby reducing the size of the apparatus. be able to.

It is the external appearance figure which showed the principal part of the speed increase / decrease device of this invention. Example 1 It is sectional drawing along the BB line in FIG. It is a cross section along the CC line in FIG. It is a fragmentary sectional view of the speed increase / decrease device of this invention. (Example 2) It is the external appearance figure which showed the principal part of the speed increase / decrease device of this invention. (Example 3)

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an increase / decrease device according to an embodiment of the present invention will be described with reference to the drawings based on examples.
In addition, the following description is given about the case where it uses as a reduction gear.

  FIG. 1 shows the main part of the speed reducer according to the first embodiment of the present invention, and is an internal appearance view in a cross section taken along the line AA of FIG. 2 is a cross-sectional view taken along line BB in FIG. FIG. 3 is a cross section taken along the line CC in FIG.

The first shaft 10 is connected to a power source such as a motor (not shown) as an input member.
The first shaft 10 is rotatably supported by the first case 12 via a first bearing 14 and a second bearing 16, and the first bearing 14 is fixed to the first case 12 in the axial direction by a cover 18. .
A first shim 18 a can be interposed between the cover 18 and the first bearing 14, and an oil seal 18 b is provided between the cover 18 and the first shaft 10.
A spiral groove 10 a is formed on the first shaft 10.

The second shaft 20 is rotatably supported by the first case 12 and the second case 22 via a third bearing 24 and a fourth bearing 26, and the second shaft 20 is interposed between the first case 12 and the third bearing 24. The third shim 22a can be interposed between the second shim 12a and the second case 22 and the fourth bearing 26, respectively.
In FIGS. 1 and 2, the first shim 18a, the second shim 12a, and the third shim 22a are exaggerated in thickness.
An oil seal 12 b and an oil seal 22 b are provided between the second shaft 20 and the first case 12 and the second case 22.

The 2nd axis | shaft 20 is connected with the driven body which is not shown in figure as an output member, and can drive this.
The second shaft 20 is hollow with a hole 20a extending in the axial direction at the center, and a disk-shaped flange 20b is formed on the outside.
Twenty-four pivots 28 are fixed at equal intervals along the pitch circle D in parallel to the second shaft 20 on the outer peripheral portion of the flange portion 20b, and the protruding portion of each pivot 28 is provided with a roller 32 via a fifth bearing 30. It is supported so as to be rotatable about the axis of the pivot 28.

The outer periphery of the roller 32 forms a spherical surface 32a, and the roller 32 meshes with the spiral groove 10a of the first shaft 10 via the spherical surface 32a.
FIG. 3 shows the meshing between the roller 32 and the spiral groove 10a as seen in a cross section along the line CC in FIG. As shown in FIG. 3, the spiral groove 10 a has a shape corresponding to the spherical surface 32 a of the roller 32.
As shown in FIGS. 1 and 2, the first shaft 10 is closer to the center of the second shaft 20 than the pitch circle D of the pivot 28 (the distance between the centers of the pivots 28 apart from each other by 180 degrees) and the first shaft 10. The central axis of the shaft 10 is arranged on the third bearing 24 side with respect to the roller 32, and the spiral groove 10a has a plurality of rollers 32-1, 32-2, 32-3, 32-4 at the same time as shown in FIG. , 32-5.

Next, the operation of the reduction gear of the first embodiment shown in FIGS. 1 and 2 will be described.
When the first shaft 10 is rotated clockwise (clockwise) when viewed from the right side in FIG. 1, the spiral groove 10 a formed in the first shaft 10 is turned into rollers 32-1, 32-2, 32-3, 32. -4 and 32-5 are pushed to the right in the axial direction of the first shaft 10 in FIG. In FIG. 1, since the first shaft 10 is drawn in appearance, the contact between the spiral groove 10a and each roller 32 is not visible, but the rollers 32-1, 32-2, 32-3, 32-4, and 32-5 are not visible. Is pushed by the spiral groove 10 a and moves to the right while rolling, and rotates the second shaft 20 to the right via each pivot 28.

  The distance between adjacent rollers 32-1, 32-2, 32-3, 32-4, and 32-5 is equal on the pitch circle, but is the axial distance of the first shaft 10. When viewed, the distance between the rollers 32-1, 32-2, and 32-3 is large, the distance between the rollers 32-3 and 32-4 is slightly smaller, and the distance between the rollers 32-4 and 32-5 is even smaller. To change.

Therefore, the spiral groove 10a of the first shaft 10 is formed by changing the lead so that the lead is not constant and is always in contact with each of the rollers 32-1, 32-2, 32-3, 32-4, and 32-5. It is.
Further, the distance between the center of the first shaft 10 and the center of the spherical surface 32a of each of the rollers 32-1, 32-2, 32-3, 32-4, and 32-5 is viewed in the axial direction of the second axis. Different.
For this reason, the depth of the spiral groove 10a from the outer diameter of the first shaft 10 is also formed so as to vary depending on the part as in the case of the above-described lead.

The spiral groove 10a of the first shaft 10 shown in FIG. 1 is the same as a so-called single-thread screw having one thread, and when the first shaft 10 makes one rotation, the rollers 32-1, 32-2, 32-3, 32-4 and 32-5 move one pitch at a time. Accordingly, when the first shaft 10 makes one rotation from the state of FIG. 1, the roller 32-1 moves to the position 32-2 in FIG. 1, and rotates the second shaft 20 by that amount.
That is, if the number of spiral grooves 10a is N1 and the number of rollers 32 is N2, the reduction ratio (the rotational speed of the first shaft 10 / the rotational speed of the second shaft 20) can be expressed by N2 / N1. In the case of 1, it is 24.

Next, backlash adjustment will be described.
When the second shaft 20 is connected to a table of a machine tool, for example, it is important to ensure the positional accuracy of the second shaft 20 in the rotational direction, and the backlash of the speed reducer is required to be as small as possible.

In the speed reducer configured as described above, factors affecting the backlash include play in the axial direction of the first shaft 10, play at the meshing portion between the roller 32 and the spiral groove 10a, and the fifth bearing. 3 is a play between the pivot 28 including the roller 30 and the roller 32.
Here, in particular, the axial play of the first shaft 10 and the adjustment of the play at the meshing portion between the roller 32 and the spiral groove 10a will be described.

First, the axial play of the first shaft 10 is adjusted by selecting the thickness of the first shim 18 a inserted between the cover 18 and the first bearing 14. In this case, it is only necessary to reduce the backlash in the axial direction of the first shaft 10, and adjustment is easy.
Next, the adjustment of the play at the meshing portion between the roller 32 and the spiral groove 10 a needs to adjust the position of the second shaft 20 with respect to the first shaft 10 in the axial direction of the second shaft 20. Therefore, the thicknesses of the second shim 12a inserted between the first case 12 and the third bearing 24 and the third shim 22a inserted between the second case 22 and the fourth bearing 26 are set to be the same. Selection can be made in any direction of the second shaft 20 in the axial direction, and these shims 12a and 22a are adjusted in accordance with the first shaft 10 positioned in advance.
In these adjustments, it is possible to reduce the backlash to zero by applying a preload to the meshing portion between the roller 32 and the spiral groove 10a.

Since the adjustment of the second shaft 20 is also a movement in the axial direction, it is easier than adjusting by moving the position of the first shaft 10 in the radial direction of the first shaft 10 as in the conventional example.
Moreover, the shape of the meshing part of the roller 32 and the spiral groove 10a is the same in all of the five contact parts of the rollers 32-1, 32-2, 32-3, 32-4, and 32-5. Since it can be said that the shape is similar and the dimensional accuracy is similar, it is possible to reduce the backlash at the same time at all five locations by simply adjusting the position of the second shaft 20 as described above.

  As can be seen from the above description, in the speed reducer of the first embodiment, there are always as many as five rollers 32 that can mesh simultaneously to transmit power between the first shaft 10 and the second shaft 20, Since the burden per roller 32, pivot 28, and fifth bearing 30 is reduced accordingly, a small speed reducer is sufficient to obtain the same output torque.

  In addition, it is easy to adjust the backlash and, as described above, the backlash of the meshing portion between the roller 32 and the spiral groove 10a can be adjusted almost at the five locations. In order to keep the rotational axis position accuracy of the second shaft 20 stable and high, and the rollers 32-1, 32-2, 32-3, 32-4, 32-5 are always robust. Leads to evenly sharing the load.

Of course, the power transmission between the first shaft 10 and the second shaft 20 is basically performed by the rolling of the roller 32. Therefore, the friction loss is significantly smaller than that of the worm gear type speed reducer and the power transmission efficiency. Is extremely high.
Also, since the second shaft 20 is hollow with a hole 20a formed in the center, it is easy to pass an electric cord or the like through the hole 20a when applied to driving a joint of an industrial robot. it can.
Further, when the transmission torque is small, it is possible to omit the fifth bearing 30 by assuming that the roller 32 is formed of resin.

Next, a reduction gear according to a second embodiment of the present invention will be described.
FIG. 4 is an enlarged partial cross-sectional view of a main part of the speed increasing / decreasing device according to the second embodiment of the present invention, and shows a meshing portion between the roller 32 and the spiral groove 10a corresponding to FIG.
Here, the description will focus on parts that are different from the first embodiment, and parts that are substantially the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

The difference between the second embodiment and the first embodiment is the shape of the meshing portion between the roller 32 and the spiral groove 10a.
That is, the outer periphery of the roller 32 forms a tapered surface 32a, and although detailed illustration is omitted, the shape of the corresponding spiral groove 10a is also a corresponding shape.
Therefore, the roller 32 and the spiral groove 10a are basically in line contact.
A sixth bearing 34 is inserted between the roller 32 and the pivot 28.

Next, the operation of the speed increasing / decreasing device according to the second embodiment of the present invention shown in FIG. 4 will be described.
As described above, only the shape of the meshing portion of the roller 32 and the spiral groove 10a and the presence of the sixth bearing 34 are different from those of the first embodiment. The same.
Further, the adjustment of the backlash and the effect thereof are basically the same as those in the first embodiment, and thus the description thereof is omitted. Therefore, also in the reduction gear of the second embodiment, the same effect as that of the first embodiment can be obtained.

Next, a reduction gear according to a third embodiment of the present invention will be described below.
FIG. 5 is a cross-sectional view of a reduction gear according to Embodiment 3 of the present invention, and corresponds to FIG.
Here, the description will focus on parts that are different from the first embodiment, and parts that are substantially the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

The difference between the third embodiment and the first embodiment is the attachment angle of the pivot 28 to the second shaft 20 and the shape of the meshing portion of the roller 32 and the spiral groove 10a.
That is, the pivot 28 is not parallel to the second shaft 20 but is fixed to the flange portion 20b at a certain angle. In this embodiment, the roller 32 side is inclined toward the radially outer side of the flange portion 20b.
Moreover, the outer periphery of the roller 32 forms the cylindrical surface 32a, and although detailed illustration is abbreviate | omitted, the shape of the corresponding spiral groove 10a is also a shape corresponding to it.
Therefore, the roller 32 and the spiral groove 10a are in line contact as in the second embodiment.

Next, the operation of the reduction gear according to the third embodiment of the present invention shown in FIG. 4 will be described.
As described above, only the mounting angle of the pivot 28 to the second shaft 20 and the shape of the meshing portion of the roller 32 and the spiral groove 10a are different from those of the first embodiment. Is basically the same.
The backlash is adjusted by the same method as in the first embodiment because the outer periphery of the roller 32 is the cylindrical surface 32a, but the angle of attachment of the pivot 28 to the second shaft 20 is not parallel to the second shaft 20. be able to. Therefore, even in the reduction gear of the third embodiment, the same effect as that of the first embodiment can be obtained.

As described above, since the speed reducer according to each embodiment of the present invention is power transmission by rolling between the roller and the spiral groove, the power transmission efficiency is high and the load per roller is small. The apparatus can be miniaturized.
Further, the backlash can be easily adjusted, and once adjusted, it is difficult for deviation to occur. Therefore, the positional accuracy in the rotational direction of the second shaft can be maintained high, and the load per roller is suitable for distribution.

The above embodiment has been described as a speed reducer. However, in the present invention, since the power transmission efficiency is high, it can sufficiently function as a speed increaser. In that case, the first axis is used as an output member and the second axis is used as an input member, and the relationship between the two is used in the opposite manner.
In that case, it is desirable to reduce the number of rollers and make the spiral groove lead as large as possible. In this case, it goes without saying that the number of rollers can be made larger than that of the prior art, although it is less than that of the reduction gear.

  Based on the general knowledge of those skilled in the art, the speed increasing / decreasing device of the present invention appropriately selects the type of each bearing according to the application, or adjusts the backlash by a method other than adjusting the thickness of the shim. And can be implemented in a modified form such as optimizing the shape of the roller outer periphery and the spiral groove

  The speed increasing / decreasing device of the present invention can be applied to machine tool table driving, industrial robot arm driving, and the like, which are required to have particularly high power transmission efficiency and high rotational direction positional accuracy. However, the present invention is not limited to this, and can be widely applied to deceleration between motors and wheels of an electric vehicle.

DESCRIPTION OF SYMBOLS 10 1st shaft 12 1st case 14 1st bearing 16 2nd bearing 18 Cover 20 2nd shaft 22 2nd case 24 3rd bearing 26 4th bearing 28 Pivot 30 5th bearing 32 Roller 34 6th bearing

Claims (5)

A first axis forming a spiral groove;
A second shaft having a plurality of rollers;
With
The second shaft has a flange portion, a plurality of pivots are provided on the outer periphery of the flange portion so as to protrude from the flange portion, and the roller is rotatably supported by a protruding portion of the pivot,
The first axis is arranged closer to the center of the second axis than the tip pitch circle of the pivot,
The speed increasing / decreasing device characterized in that the spiral groove simultaneously meshes with some of the plurality of rollers at the same time.   2. The speed increasing / decreasing device according to claim 1, wherein the pivot is provided in parallel with the second axis or at a certain angle with respect to the second axis.   The speed increasing / decreasing device according to claim 1, wherein an outer periphery of the roller forms a spherical surface, and the spiral groove has a shape corresponding to the spherical surface.   2. The speed increasing / decreasing device according to claim 1, wherein an outer periphery of the roller forms a tapered surface, and the spiral groove has a shape corresponding to the tapered surface.   A means for adjusting the position of the second axis with respect to the first axis in the previous period in the axial direction of the second axis is provided, and the backlash between the roller and the spiral groove can be adjusted. The speed increasing / decreasing device according to any one of claims 1 to 4.

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