JP6570837B2 - Decelerator - Google Patents

Description

  The present invention relates to a gear shaft.

  A transmission mechanism for transmitting the rotation of a drive motor to a driven body via a gear mechanism is known. For example, a gear shaft that rotates in response to the rotation of the drive motor, a planetary gear that meshes with the gear portion of the gear shaft, an internal gear that meshes with the planetary gear, a planetary pin that rotatably supports the planetary gear, There is known a transmission mechanism including a carrier body that supports a planetary pin and synchronizes with a revolution component of a planetary gear (see Patent Document 1).

JP 2011-52788 A

  The gear shaft of the transmission mechanism described in Patent Document 1 includes a gear portion, a connecting shaft portion that is connected to another shaft and has a larger diameter than the gear portion, and a connecting portion that is located between the gear portion and the connecting shaft portion. And comprising. The gear portion and the connecting portion are formed to have the same diameter, and therefore a step portion is formed at the boundary between the connecting portion and the connecting shaft portion. In this way, stress is likely to concentrate at the portion where the diameter of the gear shaft changes abruptly, and deformation or breakage is likely to occur due to the stress.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a gear shaft that can prevent deformation and breakage.

  In order to solve the above problems, a gear shaft according to an aspect of the present invention includes a gear portion, a connecting shaft portion connected to another shaft and having a larger diameter than the gear portion, and between the gear portion and the connecting shaft portion. A connecting shaft that is positioned so that the outer diameter gradually increases from the gear portion toward the connecting shaft.

  According to this aspect, the stepped portion is not formed at the boundary between the gear portion and the connecting portion or the boundary between the connecting portion and the connecting shaft portion.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the gear shaft which can suppress that a deformation | transformation and a failure | damage arise can be provided.

It is sectional drawing of the simple planetary gear reducer 10 which concerns on embodiment. It is an expanded sectional view which expands and shows the periphery of the sun gear shaft of FIG. It is sectional drawing of the sun gear shaft in the boundary part of a gear part and a connection part.

  Hereinafter, the same or equivalent components and members shown in the respective drawings are denoted by the same reference numerals, and repeated descriptions thereof are omitted as appropriate. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted.

  FIG. 1 is a cross-sectional view showing a simple planetary gear reducer 10 according to an embodiment. The simple planetary gear speed reducer 10 includes a sun gear shaft 12, an input shaft 28 coupled to the sun gear shaft 12, a plurality of planetary gears 14 meshing with the sun gear shaft 12, and an inner meshing engagement of the planetary gear 14. The toothed gear 16, the planetary pin 18 that rotatably supports the planetary gear 14, the carrier body 20 that supports the planetary pin 18, the bearings 22 and 24, and the carrier body 20 can be rotated via the bearings 22 and 24. A casing 26 to be supported, a bearing 64, and a cover 76 that rotatably supports the input shaft 28 via the bearing 64 are provided.

  The sun gear shaft 12 extends around the rotation axis R. One end of the sun gear shaft 12 is press-fitted into a press-fitting hole 28 a centering on a rotation axis R formed on the input shaft 28. A gear is formed at the other end of the sun gear shaft 12 and meshes with the planetary gear 14. Since the sun gear shaft 12 and the input shaft 28 are separate from each other, the reduction ratio can be changed by changing the sun gear shaft 12 to the one having a different number of gear teeth and different pitch circle diameters without changing the input shaft 28. The configuration of the sun gear shaft 12 will be described in detail with reference to FIG. An insertion hole 28b centered on the rotation axis R is formed on the side of the input shaft 28 opposite to the sun gear shaft. A motor shaft (not shown) and the output shaft of the preceding reduction gear are inserted into the insertion hole 28b.

  A plurality of planetary gears 14 are arranged on the outer periphery of the sun gear shaft 12 and revolve while rotating around the sun gear shaft 12. The planetary gear 14 is supported by the planetary pin 18 via the planetary bearing 30. In the planetary bearing 30, the needle is divided into two in the axial direction, that is, in the direction parallel to the rotation axis R, and arranged in a full roller state. Thereby, the one-side contact of the needle when the sun gear shaft 12 and the planetary gear 14 mesh with each other can be reduced. In addition, since the needle is used in a full roller state without a cage, a large torque can be transmitted to the planetary pin 18.

  The internal gear 16 is provided on the inner peripheral side of the casing 26. The internal gear 16 is formed integrally with the casing 26 including a tooth portion that meshes with the planetary gear 14. The internal gear 16 may be formed separately from the casing 26 and may be fixed to the casing 26 with screws or the like.

  The planetary pin 18 is supported by the carrier body 20. The planetary pin 18 is formed separately from the carrier body 20, but the planetary pin 18 may be formed integrally with the carrier body 20.

  The carrier body 20 includes a carrier body main body 32 and a carrier body plate 34 connected to the carrier body main body 32. The carrier body main body 32 is fastened and fixed to the carrier body plate 34 by bolts 36. The carrier body main body 32 and the carrier body plate 34 are formed with press-fit holes 32a and 34a, respectively. The ends of the planetary pin 18 are press-fitted into the press-fitting holes 32a and 34a, respectively. Therefore, the carrier body 20 takes out the revolution component of the planetary gear 14 via the planetary pin 18 and rotates in synchronization with the planetary gear 14. The formation positions of the press-fit holes 32a and 34a are changed according to the reduction ratio.

  On the side opposite to the input shaft of the carrier body 32, a flange-shaped output shaft 38 is integrally provided. A plurality of bolt holes 40 are provided on the end face of the output shaft 38, and a driven shaft of the counterpart machine is connected to the bolt hole 40 by connecting a bolt (not shown). The output shaft 38 may have a shape in which a shaft member protrudes from the center of the carrier body main body 32. An oil seal 66 is disposed between the output shaft 38 and the casing 26 in order to seal the inside and outside of the simple planetary gear reducer 10.

  The bearings 22 and 24 are arranged on the outer side in the radial direction of the carrier body 20, and support the carrier body 20 in a rotatable manner. The bearings 22 and 24 are, for example, angular ball bearings, and include balls 42 and 44 and outer rings 46 and 48, respectively. The inner rings of the bearings 22 and 24 are formed integrally with the carrier body 20. That is, the inner ring raceway surfaces of the bearings 22 and 24 are formed on the outer peripheral surfaces 50 and 52 of the carrier body 20. Therefore, compared to the case where the inner ring is provided separately from the carrier body, the thickness of the portions 32b and 34b of the carrier body 20 between the planetary pin 18 and the bearings 22 and 24 is not increased without increasing the outer shape of the casing 26. The diameter of the planetary pin 18 can be increased while ensuring the thickness. Therefore, the output torque can be improved without increasing the size of the simple planetary gear reducer 10 itself. Further, since the inner rings of the bearings 22 and 24 are integrally formed with the carrier body 20, the number of parts is reduced.

  Further, the bearings 22 and 24 are arranged apart from each other in the axial direction with the internal gear 16 interposed therebetween. The bearings 22, 24 are in particular arranged in a rear combination. For this reason, a high radial load and an axial load can be supported.

  The cover 76 includes a first cover 54 and a second cover 56. The first cover 54 is fastened and fixed to the casing 26 by bolts 58. The second cover 56 is fastened and fixed to the opposite side of the casing 26 of the first cover 54 by bolts 60. An oil seal 62 is provided between the first cover 54 and the input shaft 28. A bearing 64 is disposed inside the first cover 54, and the first cover 54 supports the input shaft 28 through the bearing 64 so as to be rotatable. The bearing 64 is sandwiched and fixed in the axial direction by the first cover 54 and the second cover 56.

  FIG. 2 is an enlarged cross-sectional view showing the periphery of the sun gear shaft 12 of FIG. FIG. 3 is a cross-sectional view of the sun gear shaft 12 at the boundary portion 74 between the gear portion 68 and the connecting portion 70. The sun gear shaft 12 includes a gear portion 68, a connecting portion 70, and a connecting shaft portion 72. The gear part 68, the connection part 70, and the connecting shaft part 72 are integrally formed by a single member. The gear portion 68 faces the planetary gear 14 in the radial direction and meshes with the planetary gear 14. The connecting shaft portion 72 is formed in a columnar shape or a cylindrical shape. The connecting shaft portion 72 is press-fitted into the press-fitting hole 28 a of the input shaft 28 and is connected to the input shaft 28.

  Here, there is a demand for realizing a large reduction ratio such as a 1/10 ratio without increasing the number of stages of the planetary gear, that is, without increasing the size of the simple planetary gear reducer 10 itself. Further, there is a demand for making the internal gear 16 common to all reduction ratios in order to reduce the number of parts. In this case, in order to realize a large reduction ratio, it is necessary to reduce the diameter of the gear portion 68. On the other hand, if the overall diameter of the sun gear shaft 12 including the gear portion 68 is reduced, a large stress is generated in the connecting shaft portion 72 when a large torque is to be obtained. Moreover, in order to ensure sufficient coupling strength between the connecting shaft portion 72 and the press-fitting hole 28a, it is desirable that the diameter of the connecting shaft portion 72 is larger. Thus, the connecting shaft portion 72 is formed with a larger diameter than the gear portion 68.

  The connecting portion 70 is located between the gear portion 68 and the connecting shaft portion 72. The connecting portion 70 is formed in a tapered shape having a larger diameter from the gear portion 68 side toward the connecting shaft portion 72 side. In the embodiment, the connecting portion 70 is formed such that the outer diameter changes in a curved manner from the gear portion 68 side toward the connecting shaft portion 72 side. That is, the connection part 70 is formed so that the cross-sectional shape of the outer peripheral surface 70a (the outer peripheral surface 70a of the peak part 70c described later) in the cross section including the rotation axis R has a curved shape.

  The connecting portion 70 is formed with a groove portion 70 b that is continuous with the tooth groove 68 a of the gear portion 68 and a peak portion 70 c that is continuous with the tooth portion 68 b of the gear portion 68. At the boundary portion 74 between the gear portion 68 and the connecting portion 70, which is a portion where the outer diameter of the sun gear shaft 12 starts to change, the diameter of the bottom portion 68c of the tooth groove 68a and the diameter of the bottom portion 70d of the groove portion 70b are the same. The tooth gap 68a and the groove portion 70b are smoothly continuous. Moreover, in the boundary part 74, the diameter of the top part 68d of the tooth part 68b and the diameter of the top part 70e of the peak part 70c are the same, and the tooth part 68b and the peak part 70c continue smoothly.

  In the boundary portion 74, the tangent line 70f of the outer peripheral surface 70a in the cross section including the rotation axis R is parallel to the axial direction (that is, parallel to the rotation axis R of the sun gear shaft 12). In other words, the cross-sectional shape of the outer peripheral surface 70a in the cross section including the rotation axis R is a curved shape close to a straight line at the boundary portion 74 as long as the radius of curvature is not infinite.

The operation of the simple planetary gear reducer 10 configured as described above will be described.
For example, the sun gear shaft 12 rotates through the input shaft 28 by the rotation of a motor (not shown). Then, the gear portion 68 of the sun gear shaft 12 and the planetary gear 14 mesh with each other, and the planetary gear 14 revolves around the sun gear shaft 12 while rotating. Since the internal gear 16 that is in mesh with the planetary gear 14 is in a fixed state, the revolution component of the planetary gear 14 is extracted from the carrier body 20. The carrier body 20 rotates the driven shaft of the counterpart machine attached to the output shaft 38.

  According to the sun gear shaft 12 of the simple planetary gear speed reducer 10 according to the embodiment described above, the connecting portion 70 is formed so that the outer diameter gradually increases from the gear portion 68 side toward the connecting shaft portion 72 side. And connected to the gear portion 68 and the connecting shaft portion 72. Therefore, no step portion is formed at the boundary portion 74 between the gear portion 68 and the connection portion 70 or at the boundary portion between the connection portion 70 and the connecting shaft portion 72. Thereby, it is suppressed that stress concentrates on these boundary parts, and it is suppressed that a deformation | transformation and a failure | damage occur in the sun gear shaft 12. FIG.

  Further, according to the sun gear shaft 12 of the simple planetary gear reducer 10 according to the embodiment, the connecting shaft portion 72 that is press-fitted into the press-fitting hole 28a of the input shaft 28 is formed to have a larger diameter than the gear portion 68, and The connecting portion 70 is formed so that the outer diameter gradually increases from the gear portion 68 side toward the connecting shaft portion 72 side. Therefore, the boundary portion 74 is not in contact with the peripheral surface of the press-fitting hole 28a. Where stress tends to concentrate on the boundary portion 74, where the diameter of the sun gear shaft 12 starts to change, the boundary portion 74 is not in contact with the peripheral surface of the press-fitting hole 28 a, so stress due to press-fitting is applied to the boundary portion 74. It is difficult. That is, the concentration of stress on the boundary portion 74 is suppressed, and deformation or breakage of the sun gear shaft 12 is suppressed.

  Further, according to the sun gear shaft 12 of the simple planetary gear speed reducer 10 according to the embodiment, the connecting portion 70 has a groove portion 70b continuous with the tooth groove 68a of the gear portion 68 and a tooth portion 68b of the gear portion 68. Crest portion 70c is formed, and at the boundary portion 74 between the gear portion 68 and the connection portion 70, the diameter of the bottom portion 68c of the tooth groove 68a and the diameter of the bottom portion 70d of the groove portion 70b become the same, and the top portion 68d of the tooth portion 68b The diameter and the diameter of the top portion 70e of the peak portion 70c are formed to be the same. Here, when the connection part 70 does not have the groove part 70b continuous with the tooth groove 68a of the gear part 68 or the crest part 70c continuous with the tooth part 68b of the gear part 68, the boundary part between the gear part 68 and the connection part 70 There is a step in 74, and stress may be concentrated. On the other hand, according to the sun gear shaft 12 of the simple planetary gear speed reducer 10 according to the embodiment, the connecting portion 70 includes the groove portion 70b continuous with the tooth groove 68a of the gear portion 68 and the gear portion 68 as described above. A crest portion 70c continuous with the tooth portion 68b is formed. As a result, no step portion is formed in the boundary portion 74, and the concentration of stress on the boundary portion 74 is suppressed, and deformation or breakage of the sun gear shaft 12 is suppressed.

  The configuration and operation of the simple planetary gear reducer according to the embodiment have been described above. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective components, and such modifications are also within the scope of the present invention.

(Modification 1)
In the embodiment, the connecting portion 70 is formed so that the outer diameter changes in a curve as it goes from the gear portion 68 side to the connecting shaft portion 72 side. That is, the connecting portion 70 is in a cross section including the rotation axis R. Although the case where the cross-sectional shape of the outer peripheral surface 70a is formed to have a curved shape has been described, the present invention is not limited thereto. The connecting portion 70 may be formed such that the outer diameter changes linearly from the gear portion 68 side toward the connecting shaft portion 72 side. That is, the connection part 70 may be formed so that the cross-sectional shape of the outer peripheral surface 70a in the cross section including the rotation axis R has a linear shape.

(Modification 2)
Although not particularly mentioned in the embodiment, the connecting portion 70 may include a portion where the outer diameter may monotonously increase from the gear portion 68 side toward the connecting shaft portion 72 side, or a portion where the outer diameter temporarily decreases. You may go out.

(Modification 3)
In the embodiment, the case where the casing is fixed and the output shaft is provided on the carrier body has been described. However, the present invention is not limited to this. The simple planetary gear speed reducer 10 may be a so-called frame rotation type speed reducer in which a carrier body is fixed and a casing rotates to obtain an output.

(Modification 4)
The technical idea of the present embodiment can be applied to any gear shaft having a gear portion, a connecting shaft portion, and a connecting portion, not limited to the sun gear shaft 12 of the simple planetary gear reducer 10.

  Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment generated by the combination has the effects of the combined embodiment and the modified examples.

  10 simple planetary gear reducer, 12 sun gear shaft, 28 input shaft, 68 gear portion, 70 connecting portion, 72 connecting shaft portion, 74 boundary portion.

Claims (4)

A sun gear shaft including a gear portion, a connecting shaft portion connected to another shaft and having a larger diameter than the gear portion, and a connecting portion positioned between the gear portion and the connecting shaft portion;
A planetary gear meshing with the gear portion;
A carrier body rotatably supporting the planetary gear,
The connecting portion has a diameter-expanding portion whose outer diameter gradually increases from the gear portion side toward the connecting shaft portion side, and at least a part of the diameter-expanding portion is connected to the carrier body and the other shaft. Are overlapping in the radial direction,
The connecting shaft portion is connected in a state that has entered the hole formed in the axial end face of the other axial press-fit with the other axes
A groove portion that is continuous with the tooth groove of the gear portion and a crest portion that is continuous with the tooth portion of the gear portion are formed in the enlarged diameter portion of the connection portion,
The end of the groove and the peak reaches the connecting shaft that is press-fitted into the other shaft .   The speed reducer according to claim 1, wherein the groove portion and the peak portion exist over the entire length of the enlarged diameter portion in the axial direction.   The speed reducer according to claim 1 or 2, wherein the diameter-expanded portion overlaps the carrier body and the other shaft in the radial direction over the entire length of the diameter-expanded portion in the axial direction. A bearing that rotatably supports the carrier body;
The speed reducer according to any one of claims 1 to 3, wherein at least a part of the enlarged-diameter portion of the connection portion overlaps the bearing in a radial direction.

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