WO2014046049A1

WO2014046049A1 - Transmission device

Info

Publication number: WO2014046049A1
Application number: PCT/JP2013/074870
Authority: WO
Inventors: 大輔松井; 佑介片岡
Original assignee: ナブテスコ株式会社
Priority date: 2012-09-21
Filing date: 2013-09-13
Publication date: 2014-03-27
Also published as: TW201422945A; CN204610711U; JP2014062588A

Abstract

A transmission device utilizes a first gear, a second gear, and a third gear. The first gear is affixed to a case and is provided with internal teeth. The third gear is affixed to an output shaft and can rotate relative to the case. If the third gear is externally toothed, the second gear is internally toothed, and if the third gear internally toothed, the second gear is externally toothed. The second gear meshes with both the first gear and the third gear. The first gear and the second gear have a difference in the number of teeth, and/or the second gear and the third gear have a difference in the number of teeth. When the second gear revolves, the third gear rotates and the output shaft rotates.

Description

Transmission

This application claims priority based on Japanese Patent Application No. 2012-207791 filed on September 21, 2012. The entire contents of that application are incorporated herein by reference. In this specification, a part of the inner teeth and a part of the outer teeth mesh with each other, a difference in the number of teeth is provided between the inner teeth and the outer teeth, and the revolution movement of the gear causes the rotation of the gear. Disclosed is a device for shifting gears.

The transmission shown in FIG. 1 is known. In FIG. 1, reference numeral 107 indicates a case, and 105 indicates internal teeth. The internal teeth 105 are fixed to the case 107, and the case 107 is also an internal gear. Reference numeral 103 indicates an external gear. External teeth 103 f are formed on the outer periphery of the external gear 103. A part of the outer teeth 103f and a part of the inner teeth 105 are engaged with each other. The number of teeth of the external teeth 103f and the number of teeth of the internal teeth 105 are different. The crankshaft 101 a passes through the center 103 e of the external gear 103. The crankshaft 101a is connected to the input shaft 101. The crankshaft 101a is offset from the input shaft 101 by a distance D. The internal teeth 105 are formed on a circumference around the input shaft 101. The external teeth 103f are formed on a circumference centering on 103e. In this specification, the center of the circumference along which the inner teeth or the outer teeth are along is referred to as the geometric center.

In the external gear 103, through

holes

103c and 103d are formed. Reference numeral 109 is an output shaft, and the tip is branched. The branched tip 109c is inserted into the through hole 103c, and the branched tip 109d is inserted into the through hole 103d. When the input shaft 101 rotates around the axis A, the geometric center 103e of the external gear 103 revolves around the axis A. When the external gear 103 revolves with respect to the internal teeth 105, the external gear 103 rotates. The external gear 103 rotates while revolving. The movement that rotates while revolving is called planetary movement in this specification. When the external gear 103 moves in a planetary motion, the output shaft 109 rotates because the

branched tips

109 c and 109 d penetrate the external gear 103. The

branched tips

109 c and 109 d and the through

holes

103 c and 103 d are torque transmission members that transmit the rotation of the external gear 103 that performs planetary motion to the output shaft 109. The gear ratio can be adjusted by adjusting the number of teeth of the external teeth 103f and the number of teeth of the internal teeth 105.

FIG. 2 exemplifies a transmission that uses two

external gears

103 and 104. The crankshaft 101 a that penetrates the external gear 103 and the crankshaft 101 b that penetrates the external gear 104 are offset in opposite directions around the input shaft 101. The branched tip 109 c of the output shaft 109 is inserted into the through hole 103 c of the external gear 103 and the through hole 104 c of the external gear 104, and the branched tip 109 d is the through hole 103 d of the external gear 103 and the external gear 104. The through hole 104d is inserted. Reference numeral 106 is an internal tooth fixed to the case 107. The same reference numerals as those in FIG. 1 indicate the same members as those in FIG.

1 and 2 are suitable for obtaining a large gear ratio, but still have limitations. Japanese Laid-Open Patent Publication No. 7-63243 (hereinafter referred to as Patent Document 1) proposes a transmission that realizes a larger gear ratio. In the apparatus of Patent Document 1, as illustrated in FIG. 3, two

external gears

103 and 104 are used to revolve in the same manner as in the apparatus of FIG.

Pins

107 c and 107 d extend from the case 107. The pin 107 c is inserted into the through hole 103 c of the external gear 103. The pin 107 d is inserted into the through hole 103 d of the external gear 103. The external gear 103 cannot rotate. When the external gear 103 revolves without rotating, the internal teeth 105 rotate. The inner teeth 105 are supported by the inner case 116 so as to be rotatable with respect to the case 107. When the inner teeth 105 rotate, the inner teeth 106 also rotate. When the external gear 104 revolves in a state where a part of the external teeth 104f and a part of the internal teeth 106 are engaged, the external gear 104 rotates. That is, the external gear 104 moves in a planetary motion. The revolutions of the external gear 104 and the output shaft 109 are related to the revolutions of the external gear 104 and the revolutions of the internal teeth 106.

In any of the structures shown in FIGS. 1 to 3, a member that transmits the rotation of the

external gears

103 and 104 that rotate while rotating (that is, planetary motion) to the output shaft 109 (in the case illustrated in FIGS. 1 to 3). Requires

branched tips

109c, 109d) that penetrate the external gears 103,104. That is, the structure shown in FIGS. 1 to 3 requires a member that transmits the rotation of the planetary gear to the output shaft. In order to reduce the size of the transmission, it is necessary to reduce the size of the member that transmits the rotation of the planetary gear to the output shaft, and the required strength cannot be ensured. The presence of the torque transmission member itself is an obstacle to downsizing the transmission. The structure illustrated in FIGS. 1 to 3 is not suitable for downsizing.

Japanese Utility Model Laid-Open No. 4-111947 (hereinafter referred to as Patent Document 2) discloses the transmission shown in FIG. This transmission also revolves using the two

external gears

103 and 104 in the same manner as in FIGS. A part of the external teeth 103f meshes with a part of the internal teeth 105, and when the external gear 103 revolves, the external gear 103 rotates. The crank pin 114 is inserted between the external gear 103 and the external gear 104, and when the external gear 103 rotates, the external gear 104 rotates. The external gear 104 rotates while revolving. The crank pin 114 is a torque transmission member that transmits the rotation of the external gear 103 to the external gear 104 while allowing relative displacement between the external gear 103 and the external gear 104. A part of the outer teeth 104 f meshes with a part of the inner teeth 106. The inner teeth 106 are fixed to the output shaft 109 via the inner case 110. When the external gear 104 moves in a planetary motion, the internal teeth 106 rotate and the output shaft 109 rotates.

The transmission shown in FIG. 4 rotates the output shaft 109 by rotating the internal teeth 106 with the external gear 104 that performs planetary motion. A torque transmission member is not required between the external gear 104 that performs planetary movement and the output shaft 109. However, a crank pin (torque transmission member) 114 is required between the external gear 103 and the external gear 104. When the structure of FIG. 4 is downsized, the crankpin 114 is also reduced in diameter, and the required strength may not be ensured. The presence of the crank pin 114 itself is an obstacle to downsizing the transmission. The structure shown in FIG. 4 is also not suitable for downsizing.

As described above, in any of the structures shown in FIGS. 1 to 4, a through-hole is provided in a planetary gear, and a torque transmission member is inserted into the through-hole. If the structure in which the through hole is provided in the gear and the torque transmission member is inserted into the through hole is reduced in size, the torque transmission member may be reduced in diameter and the required strength cannot be ensured. When the diameter of the torque transmission member is increased in order to avoid this, there is a case where the diameter of the through hole is increased and the strength required for the gear cannot be ensured. In the conventional structure, it is necessary to provide a through hole in the gear, and it is necessary to insert a torque transmission member into the through hole, which is an obstacle to miniaturization. There is a need for a structure that does not require a torque transmitting member to be inserted into the gear.

The transmission disclosed in this specification includes at least first to third gears. For example, as illustrated in FIG. 5, an internal tooth 105 is formed on the first gear 107 (which may also serve as a case). At least external teeth 103 f are formed on the second gear 103. A part of the inner teeth 105 of the first gear 107 and a part of the outer teeth 103 f of the second gear 103 are engaged with each other. In the case illustrated in FIG. 5, internal teeth 103 g are formed on the second gear 103, and external teeth 118 f are formed on the third gear 118. A part of the inner teeth 103g of the second gear 103 and a part of the outer teeth 118f of the third gear 118 are engaged with each other. Between the internal teeth 105 of the first gear 107 and the external teeth 103f of the second gear 103 meshed therewith, and between the internal teeth 103g of the second gear 103 and the external teeth 118f of the third gear 118 meshed therewith, A difference in the number of teeth is set in at least one of these.

When the difference in the number of teeth is set between the inner teeth 105 and the outer teeth 103f, the second gear 103 rotates when the second gear 103 revolves. That is, the second gear 103 performs a planetary motion. A speed change phenomenon is obtained between the revolution speed and the rotation speed of the second gear 103. In addition, when a difference in the number of teeth is set between the internal teeth 103g and the external teeth 118f, when the second gear 103 revolves, the third gear 118 rotates. A speed change phenomenon is obtained between the revolution number of the second gear 103 and the rotation number of the third gear 118.

As described above, when a difference in the number of teeth is set between the internal teeth 105 and the external teeth 103f, or between the internal teeth 103g and the external teeth 118f, the third gear 118 rotates when the second gear 103 revolves. Phenomenon is obtained. By adjusting the difference in the number of teeth, the relationship (speed ratio) between the revolution number of the second gear 103 and the rotation number of the third gear 118 can be adjusted. Note that a difference in the number of teeth may be provided between both the internal teeth 105 and the external teeth 103f and between the internal teeth 103g and the external teeth 118f.

As illustrated in FIG. 6, external teeth 103 h are formed on the second gear 103, internal teeth 120 h are formed on the third gear 120, and a part of the external teeth 103 h and a part of the internal teeth 120 h are formed. It may be a meshing relationship. Also in this case, when the second gear 103 revolves by setting a difference in the number of teeth between at least one of the internal teeth 105 and the external teeth 103f and between the external teeth 103h and the internal teeth 120h, the third gear 103 is revolved. A phenomenon in which the gear 120 rotates is obtained. By adjusting the difference in the number of teeth, the relationship (gear ratio) between the revolution number of the second gear 103 and the rotation number of the third gear 120 can be adjusted. Note that a difference in the number of teeth may be provided between both the internal teeth 105 and the external teeth 103f and between the external teeth 103h and the internal teeth 120h.

As described above, in the transmission disclosed in this specification, the internal gear 103g may be formed on the second gear 103 and the external gear 118f may be formed on the third gear 118, or the external gear 118 may be formed on the second gear 103. The teeth 103h may be formed, and the internal gear 120h may be formed on the third gear 120. That is, in the transmission disclosed in this specification, one of the second gear and the third gear has external teeth, and the other of the second gear and the third gear has internal teeth.

In the transmission disclosed in this specification, the second gear that revolves rotates the third gear. The third gear does not revolve. Therefore, the third gear can be fixed to the output shaft. The transmission disclosed in the present specification does not have a structure in which the output shaft is rotated directly by the rotation of the planetary second gear illustrated in FIGS. 1 to 3. Therefore, the torque transmission member penetrating the second gear is provided. There is no need to provide it. Further, the crank pin (torque transmission member) 114 required in the structure of FIG. 4 is not required. In the transmission disclosed in this specification, the third gear is a member that rotates the output shaft.

The third gear may be a member that rotates the output shaft with the second gear that moves in a planetary motion. Therefore, the relationship between the number of teeth of the third gear and the number of teeth of the second gear meshing with the third gear is not particularly limited. Even if the second gear and the third gear have the same number of teeth, the third gear and the output shaft can be rotated by the second gear that performs planetary motion. Even if the number of teeth of the second gear and the number of the third gear are the same, a shift phenomenon can be obtained if a difference in the number of teeth is set between the first gear and the second gear.

If a difference in the number of teeth is provided between the number of teeth of the third gear and the number of teeth of the second gear meshing with the third gear, a shift phenomenon can be obtained even in the process of rotating the third gear by the planetary second gear. Not only the torque transmission member that penetrates the second gear is unnecessary, but also the gear ratio can be adjusted by the second gear and the third gear. When there is a difference in the number of teeth between the second gear and the third gear, the number of teeth of the first gear and the second gear may be the same. If there is a difference in the number of teeth between the first gear and the second gear and between the second gear and the third gear, a shift phenomenon can be obtained, and the third gear and the output shaft are rotated. Can do.

The transmission disclosed in the present specification includes a first gear (internal teeth 105) fixed to the case 107,

third gears

118 and 120 supported so as to be able to rotate with respect to the case 107, and a third gear. An output shaft 109 fixed to 118, 120, an input shaft 101 supported so as to be able to rotate with respect to the case 107, and an eccentric oscillator that is fixed to the input shaft 101 and revolves when the input shaft 101 rotates. (The crankshaft 101a is a kind of an eccentric rocking body that revolves around the input shaft 101), and a second gear 103 that meshes with a part of the first gear 107 and a part of the

third gears

118 and 120. It has.

The second gear 103 is positioned by the eccentric rocking body 101a. When the eccentric rocker 101 a revolves around the input shaft 101, the second gear 103 revolves around the input shaft 101. A difference in the number of teeth is provided between at least one of the first gear 107 and the second gear 103 engaged with the first gear 107 and between the second gear 103 and the

third gears

118 and 120 engaged with the second gear 103. .

If there is a difference in the number of teeth between the first gear 107 and the second gear 103 meshing with the first gear 107, a gear ratio is realized between the revolution number of the second gear 103 and the rotation number of the second gear 103. The

third gears

118 and 120 can be rotated by the second gear 103 moving in a planetary motion. If there is a difference in the number of teeth between the second gear 103 and the

third gears

118 and 120 meshing with the second gear 103, the speed is changed between the revolution number of the second gear 103 and the rotation number of the

third gears

118 and 120. The

third gear

118, 120 can be rotated at least by the second gear 103 that revolves (the second gear 103 is not necessarily rotated). Since the

third gears

118 and 120 do not revolve, the output shaft 109 can be fixed to the

third gears

118 and 120. The transmission disclosed in this specification does not require a torque transmission member that penetrates the second gear 103.

The 1st example of the conventional transmission is illustrated. The 2nd example of the conventional transmission is illustrated. The 3rd example of the conventional transmission is illustrated. The 4th example of the conventional transmission is illustrated. An example of the transmission described in this specification is illustrated. The other example of the transmission described in this specification is illustrated. The top view of the transmission of 1st Example is shown. Sectional drawing of the transmission of 1st Example is shown. The top view of the transmission of 2nd Example is shown. Sectional drawing of the transmission of 2nd Example is shown.

Hereinafter, some of the technical features of the embodiments disclosed in this specification will be described. The items described below have technical usefulness independently.

(Feature 1) The geometric center of the internal teeth of the first gear, the geometric center of the internal or external teeth of the third gear, the axis of the output shaft, and the revolution center of the second gear are coaxial. is there.

(Feature 2) As illustrated in FIGS. 5 and 6, the input shaft 101, the axis of symmetry of the first gear 107 (the axis passing through the geometric center), the rotation shafts of the

third gears

118 and 120, The output shaft 109 is disposed on the first axis indicated by A. The rotation axis of the second gear 103 is disposed on a second axis (shown as B) extending in parallel with the first axis A at a position spaced a distance D from the first axis A.

(Feature 3) An input shaft 101 extending coaxially with the output shaft 109 and an eccentric rocking body 101a revolving around the axis of the input shaft 101 are added. When the eccentric oscillator 101a revolves around the axis of the input shaft 101, the second gear 103 revolves (the rotation axis B of the second gear rotates around the axis A of the input shaft 101). The eccentric oscillator 101a may be a crankshaft extending in parallel with the input shaft 101 at a position offset from the input shaft 101, or an eccentric cam having a circumference centered at a position offset from the input shaft 101. . What is necessary is just to provide the circumference surface which has a center in the position offset from the axial center of the input shaft 101, and the center revolves.

(Feature 4) The eccentric oscillator 101a has an outer periphery having a center at a position offset from the axis of the input shaft 101. A bearing is interposed between the outer periphery of the eccentric oscillator 101a and the inner periphery of the second gear 103. The second gear 103 can rotate by the bearing. The second gear 103 can freely rotate with respect to the case 107. That is, there is no relationship between the second gear 103 and the case 107 that restricts the rotation of the second gear 103. Further, there is no relation between the second gear 103 and the input shaft 101 that restricts the rotation of the second gear 103. Further, there is no relationship between the second gear 103 and the output shaft 109 that restricts the rotation of the second gear 103.

(Feature 5) As shown in FIG. 5, the second gear 103 is formed with external teeth 103f and internal teeth 103g. External teeth are formed on the third gear 118. A part of the inner teeth 103g of the second gear 103 and a part of the outer teeth 118f of the third gear 118 are engaged with each other.

(Characteristic 6) As shown in FIG. 6, the third gear 120 has internal teeth 120h. A part of the outer teeth 103h of the second gear 103 and a part of the inner teeth 120h of the third gear 120 are engaged with each other.

(Feature 7) As shown in FIG. 6, the internal teeth 105 of the first gear 107 and the internal teeth 120 h of the third gear 120 are arranged at different positions in the direction along the rotation axis of the third gear 120.

(Feature 8) The number of teeth of the external teeth 103f of the second gear 103 that meshes with the internal teeth 105 of the first gear 107 and the number of teeth of the external teeth 103h of the second gear 103 that mesh with the internal teeth 120h of the third gear 120 Some embodiments are different and some are consistent.

(Feature 9) The second gear may be constituted by a single member, or may be constituted by fixing a plurality of members.

(Feature 10) The first gear is fixed to the case, and the third gear is fixed to the output shaft. The second gear has an external tooth that meshes with the first gear, an external tooth or internal tooth that meshes with the third gear, and an opening that receives the eccentric rocking body (revolution body), and these are arranged coaxially. ing. The second gear is capable of rotating with respect to the eccentric rocking body (revolution body).

(First embodiment)
7 and 8 show an embodiment corresponding to FIG. Reference numeral 2 denotes a motor, which is fixed to the case 20 of the transmission 30. Reference numeral 6 denotes a motor rotation shaft, which rotates around the first axis A. Reference numeral 8 is a member that serves both as an input shaft and an eccentric rocking body (revolution body). The cylindrical portion 8a is coaxial with the first axis A, the eccentric cam 8b, and the cylindrical portion is coaxial with the first axis A. 8c. The cylindrical portion 8 a is supported by an output shaft (autorotated body) 24 described later by a bearing 12 so as to be capable of rotating, and the cylindrical portion 8 c is supported by the bearing 4 so as to be capable of rotating. A key groove 6 a is formed in the motor rotating shaft 6. The input shaft 8 is formed with a ridge 8d inserted into the key groove 6a. When the motor rotation shaft 6 rotates around the axis A, the input shaft 8 rotates around the first axis A.

The eccentric cam 8b has a circular outer peripheral surface. The center of the eccentric cam 8b is on the second axis B. The second axis B is offset from the first axis A by a distance D. That is, the distance c from the B axis to the outer peripheral surface of the eccentric cam 8b is constant regardless of the direction. On the other hand, the distance from the A axis to the outer peripheral surface of the eccentric cam 8b changes as shown by “a” or “b” depending on the direction.

The disc portion 16c of the second gear 16 is positioned around the eccentric cam 8b. An opening 16f is formed at the center of the disc portion 16c, and the bearing 10 is interposed between the center opening 16f and the eccentric cam 8b. When the input shaft 8 rotates around the axis A, the center axis B of the eccentric cam 8b revolves around the axis A, and the geometric center axis (spinning axis) B of the second gear 16 also revolves around the axis A. .

The second gear 16 is rotationally symmetric about the geometric central axis B. A ring-shaped gear 16b having external teeth and internal teeth is fixed to the disc portion 16c by bolts 16d. As shown in FIG. 7, a pericycloidal tooth profile is formed on the outer peripheral surface 16a of the ring gear 16b. A pericycloid tooth profile is also formed on the inner peripheral surface 16e of the ring gear 16b. The tooth profile formed on the outer peripheral surface of the ring-shaped gear 16b may be referred to as an external tooth 16a, and the tooth profile formed on the inner peripheral surface may be referred to as an internal tooth 16e. The ring gear 16b can be referred to as a second gear body. The second gear 16 is accommodated in the case 20.

The case 20 includes a bottom plate 20f, a first gear main body 20d, and an upper plate 20a, and is integrated with

bolts

20e, 20b and the like. Reference numeral 27 is an O-ring that seals the inside of the case from the atmosphere. The hole 20g is an attachment hole for fixing the transmission 30 to a robot or the like.

As shown in FIG. 7, the inner peripheral surface 20c of the first gear main body 20d is a circumferential surface centered on the axis A. A groove 20h having a semicircular cross section is formed at a predetermined interval on the inner peripheral surface 20c. A pin 18 is inserted into each groove 20h. The pin 18 can rotate in the semicircular groove 20h. The outer peripheral surface 16a of the ring gear 16b is close to the inner peripheral surface 20c of the first gear body 20d. Therefore, the pin 18 does not jump out of the groove 20h. An internal tooth 19 is formed by the pin 18 and the inner peripheral surface 20c of the first gear body 20d. The case 20 can be said to be a first gear having inner teeth 19 formed on the inner peripheral surface. The case 20 is also a first gear and an internal gear. Since the entities are together, a common reference number 20 is used for the case, the first gear, and the internal gear. For other members, common reference numbers are used even for members having the same entity, even if different names are used in terms of function.

As shown in FIG. 7, a part of the inner teeth 19 formed on the first gear 20 and a part of the outer teeth 16a formed on the outer peripheral surface of the ring-shaped gear 16b mesh with each other. In the case of FIG. 7, the center axis B of the outer teeth 16 a of the ring gear 16 b is eccentric to the right side with respect to the center axis A of the inner teeth 19. Therefore, the inner teeth 19 and the outer teeth 16a are engaged with each other on the right side of FIG. On the left side of FIG. 7, the inner teeth 19 and the outer teeth 16 are in contact but not engaged. It can be said that a part of the inner teeth 19 and a part of the outer teeth 16a mesh with each other, and a part of the inner teeth 19 and a part of the outer teeth 16a do not mesh with each other. Note that the term “mesh” in this specification means that they are meshed in appearance. The term “mesh” is different from the region where torque is transmitted between the inner and outer teeth. The number of teeth of the internal teeth 19 formed on the first gear 20 and the number of teeth of the external teeth 16 a formed on the second gear 16 do not match. In the present embodiment, the former is 30 and the latter is 29.

As shown in FIG. 8, a rotating body 24 that serves both as a third gear and an output shaft is accommodated inside the ring gear 16b. The rotating body 24 includes a third gear main body 24b and an output shaft portion 24c, and is integrated with a bolt 24a. The rotating body 24 is supported on the case 20 by

bearings

26 and 28 so as to be able to rotate. The rotation axis of the rotation body 24 (which serves as the third gear and the output shaft) is equal to the A axis.

The hole 24d is an attachment hole for fixing an object (not shown) to the rotating body 24 that also serves as an output shaft. For example, if the base side of the robot arm is fixed to the mounting hole 20g of the case 20, the tip side of the robot arm is fixed to the mounting hole 24d of the rotating body 24, and the input shaft 8 is rotated by the motor 2, the arm 2 The distal end side of the arm rotates with respect to the base side. The transmission 30 can reduce the rotational speed of the motor 2 and rotate the distal end side of the arm. Reference numeral 25 is an oil seal that stops the lubricating oil trapped in the case from leaking out of the case.

The rotation axis of the rotation body 24 (which serves as the third gear and the output shaft) is equal to the first axis A. As shown in FIG. 7, a groove 24 f having a semicircular cross section is formed at a predetermined interval on the outer peripheral surface 24 e centering on the first axis A. A pin 22 is inserted into each groove 24f. The pin 22 can rotate in the groove 24f. As shown in FIG. 7, the inner peripheral surface 16e of the ring gear 16b is close to the outer peripheral surface 24e of the third gear body 24b. Therefore, the pin 22 does not jump out of the groove 24f. External teeth 23 are formed by the entire outer peripheral surface 24e of the pin 22 and the third gear body 24b.

As shown in FIG. 7, a pericycloidal tooth profile is formed on the inner peripheral surface 16e of the ring gear 16b. A part of the outer teeth 23 of the third gear body 24b and a part of the inner teeth 16e formed on the inner peripheral surface of the ring-shaped gear 16b mesh with each other. In the case of FIG. 7, the center axis B of the inner teeth 16e of the ring gear 16b is eccentric to the right side with respect to the center axis A of the outer teeth 23. Therefore, the inner teeth 16e and the outer teeth 23 are deeply engaged with each other on the left side of FIG. On the right side of FIG. 7, the inner teeth 16e and the outer teeth 23 are in contact with each other but are not engaged with each other. The number of teeth of the external teeth 23 of the third gear body 24b does not match the number of teeth of the internal teeth 16e of the ring gear 16b. In this embodiment, the former is 20 and the latter is 19.

The operation of the transmission 30 will be described. When the motor 2 is driven and the motor rotation shaft 6 rotates around the axis A, the central axis B of the eccentric cam 8b revolves around the axis A, and the second gear 16 revolves following the rotation. Since there is a difference in the number of teeth between the internal teeth 19 and the external teeth 16a, when the second gear 16 revolves with respect to the first gear 20, the second gear 16 rotates. A bearing 10 is inserted between the second gear 16 and the eccentric cam 8b, and the second gear 16 can rotate.

Since the number of teeth is provided between the inner teeth 16e and the outer teeth 23, when the second gear 16 revolves, the third gear 24 rotates. When the second gear 16 rotates, the rotation number of the second gear 16 affects the rotation number of the third gear 24. In the present embodiment, the rotation direction of the third gear 24 caused by the revolution of the second gear 16 and the rotation direction of the second gear 16 are opposite to each other. That is, “the rotation speed of the third gear 24” = “the rotation speed of the third gear 24 caused by the revolution of the second gear 16” − “the rotation speed of the second gear 16”. Therefore, the rotation speed of the third gear 24 is extremely slow. The transmission 30 can obtain a large transmission ratio.

In the above embodiment, the number of teeth of the external teeth 23 of the third gear 24 and the number of teeth of the internal teeth 16e of the second gear 16 are different. However, providing a difference in the number of teeth is not indispensable, and they may be matched. Even if both coincide, the third gear 24 can be rotated by the second gear 16 that moves in a planetary motion. In this case, the rotation speed of the third gear 24 generated by the revolution of the second gear 16 becomes zero, and the relationship of “absolute value of the rotation speed of the third gear 24” = “absolute value of the rotation speed of the second gear 16” and Become. Further, by selecting the number of teeth, it is possible to obtain the relationship of “the rotation speed of the third gear 24” = “the rotation speed due to the revolution of the second gear 16” + “the rotation speed due to the rotation of the second gear 16”. . In this embodiment, the number of teeth is selected so that the sign of the rotation speed of the third gear 24 matches the sign of the rotation speed of the input shaft 8. By selecting the number of teeth, the sign of the rotation speed of the third gear 24 and the sign of the rotation speed of the input shaft 8 can be made different. That is, the rotation direction of the motor 2 and the rotation direction of the output shaft portion 24c can be aligned, or can be opposite.

In the transmission 30 described above, the rotational force is transmitted to the third gear main body 24b integrated with the output shaft portion 24c. The transmission 30 does not need the branching

tips

109c and 109d shown in FIGS. 1, 2 and 3 in order to transmit the rotational force to the output shaft. In the case of a system in which torque is transmitted using the

branch tips

109c and 109d, the problem that the strength of the

branch tips

109c and 109d is insufficient must be dealt with. This hinders downsizing of the transmission. The structure itself in which the

branch tips

109c and 109d are required also prevents miniaturization. Further, the presence of the

branch tips

109c and 109d increases the manufacturing cost. In this embodiment, the rotational force is transmitted to the third gear body 24b that rotates around the rotation axis (A axis) of the output shaft portion 24c. Therefore, the transmission 30 does not require the

branch tips

109c and 109d, and is suitable for downsizing the transmission.

Further, according to the present embodiment, the internal teeth 19 of the first gear 20 and the external teeth 16a of the second gear 16 meshing therewith, and the external teeth 23 of the third gear 24 and the internal teeth 16e of the second gear 16 meshing therewith are coplanar. Can be put inside. The thickness of the transmission 30 in the direction along the rotation axis A can be reduced. In this embodiment, the second gear 16 is composed of a plurality of members. Since the second gear itself may move as a unit, it may be constituted by a single member.

In the above embodiment, the number of teeth of the external teeth 23 of the third gear body 24b and the number of teeth of the internal teeth 16e of the second gear 16 are different. However, providing a difference in the number of teeth is not indispensable, and they may be matched. Even if both coincide, the third gear 24 can be rotated by the second gear 16 that moves in a planetary motion. If there is a difference in the number of teeth between the first gear and the second gear, a shift phenomenon can be obtained even if there is no difference in the number of teeth between the second gear and the third gear. If there is a difference in the number of teeth between the first gear and the second gear and between the second gear and the third gear, a shift phenomenon can be obtained, and the third gear and the output shaft are rotated. Can do.

(Second embodiment)
9 and 10 show an embodiment corresponding to FIG. For members equivalent to those shown in FIGS. 7 and 8, reference numbers obtained by adding 40 to the reference numbers given to the members in FIGS. 7 and 8 are used. Reference numeral 42 denotes a motor, which is fixed to the case 60 of the transmission 70. Reference numeral 46 denotes a motor rotation shaft, which rotates around the axis A. External teeth 46 a are formed on the motor rotation shaft 46. Reference numeral 44 is a spur gear. The spur gear 44 rotates around a rotation shaft 47b fixed by a bolt 47a.

Reference numeral 48 is an eccentric oscillator. The eccentric oscillating body 48 includes an eccentric oscillating body main body 48b and an upper plate 48c, and is integrated by a bolt 48d. Inner teeth are formed on the inner peripheral surface 48 e of the upper plate 48 c and mesh with the outer teeth of the spur gear 44. When the motor rotating shaft 46 rotates around the axis A, the eccentric rocking body 48 also rotates around the axis A. The inner periphery of the eccentric oscillator main body 48b is a circle centered on the axis A, and is supported by

bearings

49a and 49b. The

bearings

49a and 49b are arranged at positions centered on the axis A.

The outer peripheral surface 48a of the eccentric oscillator body 48b is circular, but its center is on the B axis. The B axis is offset from the A axis by a distance D. That is, the distance c from the B axis to the outer peripheral surface 48a is constant regardless of the direction. On the other hand, the distance from the A axis to the outer peripheral surface 48a changes as shown by “a” or “b” depending on the direction.

A second gear 56 is positioned around the eccentric rocking body 48b. The second gear 56 includes an upper part 56d and a lower part 56f. The upper part 56d and the lower part 56f are fixed by a bolt 56e. The inner peripheral surface 56c of the second gear 56 is circular. The second gear 56 is supported by the

bearings

50a and 50b so as to be rotatable around the outer peripheral surface 48a of the eccentric oscillator main body 48b. The second gear 56 rotates around the axis B. The upper outer peripheral surface 56a and the lower outer peripheral surface 56b of the second gear 56 are also centered on the axis B.

When the motor rotation shaft 46 rotates around the axis A, the eccentric rocker 48 also rotates around the axis A. The central axis B of the outer peripheral surface 48a of the eccentric oscillator main body 48b revolves around the axis A. As a result, the geometric center axis (spinning axis) B of the second gear 56 also revolves around the axis A.

A pericycloidal tooth profile is formed on the upper outer peripheral surface 56a of the second gear 56, and a pericycloidal tooth profile is also formed on the lower outer peripheral surface 56b of the second gear 56. The tooth profile formed on the upper outer peripheral surface may be referred to as an external tooth 56a, and the tooth profile formed on the lower outer peripheral surface may be referred to as an external tooth 56b.

The case 60 includes a bottom plate 60f, a cylindrical portion 60c, and an upper plate 60a, and is integrated with

bolts

60e, 60b and the like. The hole 60g is an attachment hole for fixing the transmission 70 to a robot or the like. The inner peripheral surface of the cylindrical portion 60c is a circumferential surface centering on the axis A. As shown in FIG. 9, a groove 60h having a semicircular cross section is formed at a predetermined interval on the inner peripheral surface of the cylindrical portion 60c. A pin 58 is inserted into each groove 60h. The pin 58 can rotate within the semicircular groove 60h. As shown in FIG. 10, the lower outer peripheral surface 56b of the second gear 56 is close to the inner peripheral surface of the cylindrical portion 60c, and the pin 58 does not jump out of the groove 60h. Internal teeth 59 are formed by the pins 58 and the inner peripheral surface of the cylindrical portion 60c. The case 60 can be said to be a first gear having inner teeth 59 formed on the inner peripheral surface.

As shown in FIG. 10, a part of the inner teeth 59 formed on the first gear 60 and a part of the outer teeth 56 b formed on the outer peripheral surface of the second gear 56 are meshed with each other. In the case of FIG. 10, the center axis B of the outer teeth 56 b of the second gear 56 is eccentric to the left with respect to the center axis A of the inner teeth 59. Therefore, the inner teeth 59 and the outer teeth 56b are deeply engaged on the left side of FIG. On the right side of FIG. 10, the inner teeth 59 and the outer teeth 56b are in contact with each other, but are not engaged with each other. The number of teeth of the internal teeth 59 formed on the first gear 60 and the number of teeth of the external teeth 56b formed on the second gear 56 do not match. In the present embodiment, the former is 71 and the latter is 70.

Rotating body 64 that serves both as the third gear and the output shaft is disposed outside the upper outer peripheral surface 56a of the second gear 56. The rotation body 64 is obtained by integrating a third gear body 64b and an upper plate 64d with bolts 64c. The rotating body 64 is supported on the case 60 by

bearings

66 and 68 so as to be able to rotate. The rotation axis of the rotation body 64 (which serves as the third gear and the output shaft) is equal to the A axis.

The hole 64e is a mounting hole for fixing an object (not shown) to the rotating body 64 that also serves as an output shaft. For example, when the base side of the robot arm is fixed to the mounting hole 60g of the case 60 and the tip side of the robot arm is fixed to the mounting hole 64e of the rotating body 64 and the motor 42 is driven, In contrast, the tip side of the arm rotates. The transmission 70 can reduce the rotational speed of the motor 42 and rotate the distal end side of the arm.

The rotation axis of the rotation body 64 (which serves both as the third gear and the output shaft) is equal to the A axis. As shown in FIG. 9, semicircular grooves 64f are formed at predetermined intervals on the inner peripheral surface 64a centering on the A axis. A pin 62 is inserted into each groove 64f. The pin 62 can rotate in the groove 64f. As shown in FIG. 9, the upper outer peripheral surface 56a of the second gear 56 is close to the inner peripheral surface 64a of the rotating body 64 that also serves as the third gear. Therefore, the pin 62 does not jump out of the groove 64f. Internal teeth 63 are formed by the entire inner peripheral surface 64 a of the pin 62 and the rotating body 64.

A pericycloidal tooth profile is formed on the outer peripheral surface 56 a of the second gear 56. As shown in FIG. 9, a part of the inner teeth 63 of the rotating body 64 that also serves as the third gear and a part of the outer teeth 56 a formed on the outer peripheral surface of the second gear 56 mesh with each other. In the case of FIG. 9, the center axis B of the outer teeth 56 a of the second gear 56 is eccentric to the left with respect to the center axis A of the inner teeth 63. For this reason, the inner teeth 63 and the outer teeth 56a are deeply engaged with each other on the left side of FIG. On the right side of FIG. 9, the inner teeth 63 and the outer teeth 56a are in contact with each other, but are not engaged with each other. The number of teeth of the external teeth 56a of the second gear 56 does not match the number of teeth of the internal teeth 63 of the rotating body 64 that is also the third gear. In this embodiment, the former is 70 and the latter is 69.

The operation of the transmission 70 will be described. When the motor 42 is driven and the motor rotation shaft 46 rotates around the axis A, the eccentric oscillator 48 rotates around the axis A via the spur gear 44, and the central axis of the outer peripheral surface 48a of the eccentric oscillator main body 48b. B revolves around axis A. As a result, the geometric center axis (spinning axis) B of the second gear 56 also revolves around the axis A. Since the number of teeth of the first gear 60 and the second gear 56 is different, when the second gear 56 revolves with respect to the first gear 60, the second gear 56 rotates.

Bearings

50a and 50b are inserted between the second gear 56 and the eccentric oscillator main body 48b, so that the second gear 56 can rotate.

Since there is a difference in the number of teeth between the third gear 64 and the second gear 56, when the second gear 56 revolves, the third gear 64 rotates. When the second gear 16 rotates, the rotation of the second gear 16 affects the number of rotations of the third gear 64. In this embodiment, “the rotation speed of the third gear 64” = “the rotation speed of the third gear 64 caused by the revolution of the second gear 56” − “the rotation speed of the second gear 56”. Therefore, the rotation speed of the third gear 64 is extremely slow. The transmission 70 can obtain a large transmission ratio.

In the above embodiment, the number of teeth of the inner teeth 63 of the third gear 64 is different from the number of teeth of the outer teeth 56a of the second gear 56. However, it is not essential to provide a difference in the number of teeth between the inner teeth 63 and the outer teeth 56a, and they may be matched. Even if the number of teeth of both is the same, the third gear 64 can be rotated by the second gear 56 that moves in a planetary motion. In this case, the rotation speed of the third gear 64 generated by the revolution of the second gear 56 becomes zero, and the relationship of “absolute value of the rotation speed of the third gear 64” = “absolute value of the rotation speed of the second gear 56” Become.

In the case of the transmission 70 described above, the rotational force is transmitted to the rotating body 64 that also serves as the output shaft and the third gear. In order to transmit the rotational force to the output shaft, the branching

tips

109c and 109d shown in FIGS. 1, 2 and 3 are not required. In the case of a system that transmits torque using the

branch tips

109c and 109d, downsizing of the transmission is hindered. In this embodiment, the rotational force is transmitted to the rotating body 64 that also serves as the output shaft and the third gear, so that the branching

tips

109c and 109d are not required. Therefore, the transmission of the embodiment is suitable for downsizing.

In the above embodiment, the case (first gear) is fixed (immobilized) and the output (rotation) is taken out from the output shaft (third gear). However, the output shaft (third gear) is fixed and the case is fixed. The output (rotation) may be extracted from the (first gear).

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Claims

Comprising at least a first gear, a second gear and a third gear;
The first gear has internal teeth,
At least external teeth are formed on the second gear, a part of the first gear meshes with a part of the second gear,
An external tooth is formed on one of the second gear and the third gear, an internal tooth is formed on the other of the second gear and the third gear, and a part of the second gear and one of the third gears are formed. The parts are engaged,
The difference in the number of teeth is provided in at least one of “between the first gear and the second gear” and “between the second gear and the third gear”,
A transmission comprising a third gear rotating when the second gear revolves.
The geometric center of the first gear, the geometric center of the third gear, and the axis of the output shaft are arranged coaxially,
The transmission according to claim 1, wherein the geometric center of the second gear is offset from the shaft.
The first gear also serves as the case,
The third gear and the output shaft are fixed,
The transmission according to claim 2, wherein the third gear and the output shaft are supported so as to be capable of rotating with respect to the case.
An input shaft extending coaxially with the output shaft;
An eccentric oscillator that revolves around the axis of the input shaft has been added,
The transmission according to claim 3, wherein the second gear revolves when the eccentric oscillator revolves around the axis of the input shaft.
The eccentric oscillator has an outer periphery centered at a position offset from the axis of the input shaft,
The transmission according to claim 4, wherein a bearing is interposed between the outer periphery of the eccentric oscillator and the inner periphery of the second gear.
The second gear is formed with external teeth that mesh with the first gear and internal teeth that mesh with the third gear,
External teeth are formed on the third gear,
The transmission according to any one of claims 1 to 5, wherein a part of the inner teeth of the second gear and a part of the outer teeth of the third gear mesh with each other.
The second gear is formed with external teeth that mesh with the first gear and external teeth that mesh with the third gear.
Internal teeth are formed on the third gear,
The transmission according to any one of claims 1 to 5, wherein a part of the outer teeth of the second gear and a part of the inner teeth of the third gear mesh with each other.
A first gear fixed to the case;
A third gear supported so as to be able to rotate with respect to the case;
An output shaft fixed to the third gear;
An input shaft supported so as to be able to rotate with respect to the case;
An eccentric rocking body fixed to the input shaft and revolving when the input shaft rotates;
A second gear positioned by the eccentric rocking body and meshing with a part of the first gear and a part of the third gear;
A transmission having a gear number difference provided in at least one of “between the first gear and the second gear” and “between the second gear and the third gear”.
The transmission according to claim 8, wherein the second gear is supported so as to be rotatable with respect to the eccentric rocking body.