JP2021001652A - Multi-stage planetary roller type power transmission device - Google Patents

Abstract

To provide a multi-stage planetary roller type power transmission device capable of suppressing the deterioration of rotation accuracy or the deterioration of power transmission performance, with an inexpensive structure.SOLUTION: A multi-stage planetary roller type power transmission device 1 includes a first sun shaft 11, a first fixed ring 12, a first planetary roller 13, a first carrier 14, a second sun shaft 21, a second fixed ring 22, a second planetary roller 23, a second carrier 24, and a ball bearing 30. The ball bearing 30 has an outer ring 31 disposed between the first fixed ring 12 and the second fixed ring 12, an inner ring 32 pressed in an outer periphery of the first carrier 14, and a plurality of balls 33 disposed between the outer ring 31 and the inner ring 32. The outer ring 31 is disposed while end surfaces on both sides in an axial direction thereof are contacted with the first fixed ring 12 and the second fixed ring 22. The ring 32 is disposed while the end surfaces on both sides in the axial direction thereof are not contacted with the first fixed ring 12 and the second fixed ring 22 and are contacted with the first planetary roller 13 and the second planetary roller 23.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-stage planetary roller type power transmission device.

In the fields of machine tools and industrial machines, a multi-stage planetary roller type power transmission device is used as a speed reducer capable of power transmission with low noise and low vibration (see Patent Document 1). For example, as shown in FIG. 4, the two-stage planetary roller type power transmission device 100 includes a first-stage power transmission mechanism 101 and a second-stage power transmission mechanism 102. Each of these power transmission mechanisms 101 and 102 includes a fixed wheel 111, a sun axis 112, a plurality of planetary rollers 113, and a carrier 114.

The fixed wheel 111 is fixed to the inner peripheral surface of the housing 103, and a plurality of planet rollers 113 are arranged on the inner peripheral surface 111a of the fixed wheel 111. A collar ring 115 is provided on both sides of each fixed ring 111 in the axial direction. A spacer 104 is provided between the two collar wheels 115 arranged between the fixed wheels 111. Each planet roller 113 is rotatably supported by a support shaft 116 fixed to a carrier 114. At the center of the plurality of planetary rollers 113, a sun axis 112 that contacts the outer peripheral surface of each planetary roller 113 is arranged.

One end of the solar shaft 112A of the first stage power transmission mechanism 101 is rotatably supported by the housing 103 via a rolling bearing 105. At the other end of the sun shaft 112A, the central portion of the carrier 114A of the first stage power transmission mechanism 101 is rotatably supported via a rolling bearing 106.
One end of the solar shaft 112B of the second stage power transmission mechanism 102 is press-fitted into the central portion of the carrier 114A. The other end of the sun shaft 112B is rotatably supported by the central portion of the carrier 114B of the second stage power transmission mechanism 102 via a rolling bearing 107. Further, an output shaft 108 is press-fitted into the central portion of the carrier 114B, and the output shaft 108 is rotatably supported by the housing 103 via a rolling bearing 109.

In the above configuration, the planetary rollers 113 of the power transmission mechanisms 101 and 102 come into contact with the outer circumference of the sun shaft 112 and the inner circumference of the fixed wheel 111 with a predetermined pressure contact force, and traction oil is applied to these contact surfaces. ing. Then, the rotational power of the sun shaft 112 is transmitted to each planet roller 113 by the shearing force of the traction oil, so that each planet roller 113 rotates around the support shaft 116 and the inner peripheral surface 111a of the fixed wheel 111 It revolves around the sun axis 112 while rolling on it. As a result, the rotational power of the solar shaft 112A of the first-stage power transmission mechanism 101, which is the input shaft, is transmitted to the solar shaft 112B of the second-stage power transmission mechanism 102 via the carrier 114A, and the rotational power of the solar shaft 112B is transmitted. , Is transmitted to the output shaft 108 via the carrier 114B.

Japanese Unexamined Patent Publication No. 7-54946

In the two-stage planetary roller type power transmission device 100, if the flange wheel 115 and the spacer 104 are not provided, the planetary rollers 113 of the power transmission mechanisms 101 and 102 move in the axial direction with respect to the support shaft 116 when skewed. It becomes easier to do. As a result, the moved planet roller 113 may interfere with other members, resulting in a decrease in rotational accuracy and a decrease in power transmission ability.

Further, if the rolling bearings 106 and 107 that support the carriers 114A and 114B are not provided, the solar shaft 112B can easily move together with the carriers 114A in the axial direction. As a result, the end faces of the adjacent sun shafts 112A and 112b come into surface contact with each other, and the end faces of the sun shaft 112B and the output shaft 108 come into surface contact with each other, resulting in a decrease in rotational accuracy and a decrease in power transmission capability. May lead to.

As described above, in the conventional two-stage planetary roller type power transmission device 100, the movement of the planetary rollers 113 of the power transmission mechanisms 101 and 102 and the solar axis 112B of the second-stage power transmission mechanism 102 in the axial direction is restricted. Therefore, a spacer 104, a plurality of flange wheels 115, and a plurality of rolling bearings 106 and 107 are required, which increases the number of parts and increases the cost.

Therefore, an object of the present invention is to provide a multi-stage planetary roller type power transmission device capable of suppressing a decrease in rotational accuracy and a decrease in power transmission ability with an inexpensive configuration.

(1) The present invention includes a first sun axis, a first fixed ring arranged radially outside the first sun axis, concentrically with the axis of the first sun axis, and the first sun axis. A plurality of first planet rollers provided between the first fixed wheel and the first fixed wheel, and the plurality of first planet rollers are arranged on one side in the axial direction and rotatably support each of the first planet rollers. Along with this, an annular first carrier that rotates in conjunction with the revolution of the first planet roller, a second sun axis whose end on the other side in the axial direction is press-fitted into the inner circumference of the first carrier, and the second sun. Between the second fixed ring arranged concentrically with the axis of the second sun axis and between the second sun axis and the second fixed ring on the radial outer side of the end on one side in the axial direction of the shaft. The plurality of second planet rollers provided in the above and the plurality of second planet rollers are arranged on one side in the axial direction, and each of the second planet rollers is rotatably supported and revolved around the second planet rollers. A multi-stage planetary roller type power transmission device including a second carrier that rotates in conjunction with the outer ring, an outer ring arranged between the first fixed wheel and the second fixed wheel, and an outer circumference of the first carrier. The outer ring is provided with an inner ring press-fitted into a ball bearing having a plurality of balls rotatably arranged between the outer ring and the inner ring, and the outer ring has end faces on both sides in the axial direction of the first fixed ring and the first fixed ring. The inner ring is arranged in contact with the second fixed ring, and the end faces on both sides in the axial direction thereof are not in contact with the first fixed ring and the second fixed wheel, and the first planet It is a multi-stage planetary roller type power transmission device that is arranged so as to be in contact with the roller and the second planetary roller.

According to the present invention, the outer ring of the ball bearing is arranged in a state where the end faces on both sides in the axial direction are in contact with the first fixed ring and the second fixed ring, and the inner ring is arranged with respect to the outer ring via the ball. Therefore, the movement of the inner ring to both sides in the axial direction is restricted. As a result, the movement of the first carrier in which the inner ring is press-fitted and the second solar axis press-fitted into the first carrier in both axial directions is restricted.
Further, when the first planet roller skews and moves in the axial direction toward the first carrier side, the first planet roller comes into contact with one end surface in the axial direction of the inner ring of the ball bearing, so that the movement of the first planet roller moves. Be restricted. Similarly, when the second planet roller skews and moves axially toward the first carrier side, the second planet roller comes into contact with the other end surface in the axial direction of the inner ring of the ball bearing, so that the second planet roller moves. Is restricted.

From the above, it is possible to limit the movement of the second sun axis to both sides in the axial direction by using a single ball bearing, and the axial direction of the first planet roller and the second planet roller toward the first carrier side. Movement can be restricted. As a result, the number of parts is reduced compared to the case where the spacer and the two flange wheels are arranged between the pair of fixed wheels and the rolling bearings are arranged on the pair of carriers as in the conventional case, so that the configuration is inexpensive. Axial movement of the first planet roller, the second planet roller, and the second sun axis can be restricted. As a result, it is possible to suppress a decrease in rotation accuracy and a decrease in power transmission ability.

(2) It is preferable that the outer diameter of the first sun shaft and the outer diameter of the second sun shaft are the same, and the first fixed ring and the second fixed wheel are made of the same member.
In this case, since the first fixed wheel and the second fixed wheel can be shared by the same member, the types of parts constituting the multi-stage planetary roller type power transmission device can be reduced. Further, since the first fixed wheel and the second fixed wheel are the same member and the outer diameter of the first sun axis and the outer diameter of the second sun axis are the same, the radial position of the first fixed wheel The radial position of the second fixed wheel matches, and the radial position of the first planet roller and the radial position of the second planet roller match. As a result, the outer ring of the ball bearing can be easily positioned with respect to the first and second fixed wheels, and the inner ring of the ball bearing can be positioned with respect to the first and second fixed wheels and the first and second planetary rollers. Can be easily performed.

(3) It is preferable that the first planet roller and the second planet roller are made of the same member.
In this case, the types of parts constituting the multi-stage planetary roller type power transmission device can be further reduced.

According to the present invention, it is possible to suppress a decrease in rotational accuracy and a decrease in power transmission ability with an inexpensive configuration.

It is sectional drawing of the multistage planetary roller type power transmission apparatus which concerns on embodiment of this invention. It is an enlarged sectional view of the main part of FIG. It is an enlarged sectional view which shows the modification of the multi-stage planet roller type power transmission device. It is sectional drawing of the conventional two-stage planet roller type power transmission apparatus.

[overall structure]
FIG. 1 is a cross-sectional view of a multi-stage planetary roller type power transmission device according to an embodiment of the present invention.
The multi-stage planetary roller type power transmission device 1 of the present embodiment is a traction drive type two-stage planetary roller type power transmission device, and includes a housing 4, a power transmission shaft 5, a first stage power transmission mechanism 10, and a second stage power transmission mechanism. A step power transmission mechanism 20 and a ball bearing 30 are provided. In the present specification, one side of the power transmission shaft 5 in the longitudinal direction is referred to as "one side in the axial direction", and the other side is referred to as "the other side in the axial direction".

The housing 4 is made of an aluminum alloy or the like, and includes a housing body 41 and a lid 42. The housing body 41 is formed in a bottomed cylindrical shape, and the other side in the axial direction is open. A mounting hole 41a for mounting a rolling bearing 7, which will be described later, is formed at the bottom of the housing body 41 on one side in the axial direction. On the inner circumference of the housing body 41, a step extending in the radial direction at the boundary between the large diameter surface 41b, the small diameter surface 41c formed on one side of the large diameter surface 41b in the axial direction, and the boundary between the large diameter surface 41b and the small diameter surface 41c. A surface 41d is formed.

The lid body 42 is formed in a disk shape and is arranged on the other side of the housing body 41 in the axial direction. The outer peripheral portion of the lid body 42 is fixed to the end surface of the housing body 41 on the other side in the axial direction by bolts 43. A mounting hole 42a for mounting the rolling bearing 6, which will be described later, is formed in the center of the lid body 42.

[Structure of 1st stage power transmission mechanism]
The first-stage power transmission mechanism 10 includes a first sun shaft 11, a first fixed wheel 12, a plurality of first planet rollers 13, and a first carrier 14.
The first sun axis 11 is formed in a cylindrical shape and is inserted into the mounting hole 42a of the lid body 42. The first solar shaft 11 is, for example, an input shaft into which rotational power from a motor is input, and the other end of the first sun shaft 11 in the axial direction is connected to the output shaft of the motor via a coupling or the like. It is integrally rotatably connected.

The axial intermediate portion of the first sun shaft 11 is rotatably supported by a rolling bearing 6 mounted in the mounting hole 42a. The rolling bearing 6 rolls between the outer ring 6a which is press-fitted and fixed to the inner surface of the mounting hole 42a, the inner ring 6b which is press-fitted and fixed to the outer peripheral surface of the first sun shaft 11, and the outer ring 6a and the inner ring 6b. It is a ball bearing having a plurality of balls (rolling bodies) 6c arranged freely.

The first fixed ring 12 is formed of an annular body, and is arranged concentrically with the axis C of the first sun axis 11 on the radial outer side of the first sun axis 11. The outer peripheral surface of the first fixed wheel 12 is fixed to the housing body 41 by being press-fitted into the large-diameter surface 41b on the inner circumference of the housing body 41.

The first planet roller 13 is formed in a cylindrical shape and is arranged between the first sun axis 11 and the first fixed wheel 12. In this embodiment, for example, 3 to 4 first planet rollers 13 are arranged at equal intervals in the circumferential direction. The axial width of the first planet roller 13 is slightly smaller than the axial width of the first fixed wheel 12.

The first planet roller 13 is in rolling contact with the outer peripheral surface of the first sun axis 11 on one side in the axial direction and the inner peripheral surface 12b of the first fixed wheel 12. Further, the diameter of the first planet roller 13 is slightly larger than the radial dimension between the outer circumference of the first sun axis 11 and the inner circumference of the first fixed ring 12. Therefore, the first planet roller 13 is in contact with the first sun axis 11 and the first fixed wheel 12 with a predetermined pressure contact force. In other words, the first sun axis 11 and the first planet roller 13 are incorporated to the inner circumference of the first fixed wheel 12 to the extent that they are inflicted.

Traction oil is applied to the contact surface between the first sun axis 11 and the first planet roller 13 and the contact surface between the first planet roller 13 and the first fixed wheel 12. Then, when the first sun axis 11 rotates, the rotational power is transmitted to the first planet roller 13 by the shearing force of the traction oil, and the first planet roller 13 revolves on the inner peripheral surface 12b of the first fixed wheel 12.

The first carrier 14 is made of an annular body, and the outer peripheral surface of the plurality of first planet rollers 13 is arranged so as to face the large diameter surface 41b of the housing 4 on one side in the axial direction. A plurality of peripheral holes 14a corresponding to the plurality of first planet rollers 13 are formed on the outer peripheral side of the first carrier 14, and one end of the first support shaft 15 in the axial direction is press-fitted into each peripheral hole 14a. Is fixed.

The first support shaft 15 is formed in a cylindrical shape, and the end portion of the first support shaft 15 on the other side in the axial direction is inserted into the inner circumference of the first planet roller 13 and is in sliding contact with the inner peripheral surface thereof. Therefore, a slight gap that allows slippage is formed between the outer peripheral surface of the first support shaft 15 and the inner peripheral surface of the first planet roller 13. Therefore, the first planet roller 13 can be rotatably supported with respect to the first support shaft 15 and can move in the axial direction.

A collar ring 8 is arranged on the other side of the first fixed wheel 12 in the axial direction. The collar ring 8 is formed in an annular shape and is sandwiched between the first fixed ring 12 and the lid body 42. The outer diameter of the collar ring 8 is the same as or slightly smaller than the large diameter surface 41b of the housing body 41. The inner diameter of the collar ring 8 is smaller than the inner diameter of the first fixed ring 12, and the radial inner end of the collar ring 8 projects radially inward from the inner peripheral surface 12b of the first fixed ring 12. There is. As described above, the first planet roller 13 that rolls on the inner peripheral surface 12b of the first fixed wheel 12 can move in the axial direction with respect to the first support shaft 15, but the collar 8 allows the first planet roller. The movement of 13 to the other side in the axial direction is restricted.

[Structure of second-stage power transmission mechanism]
Similar to the first stage power transmission mechanism 10, the second stage power transmission mechanism 20 includes a second sun shaft 21, a second fixed wheel 22, a plurality of second planet rollers 23, and a second carrier 24. ing.
The second sun axis 21 is formed in a cylindrical shape and is arranged concentrically with the axis C of the first sun axis 11 on one side in the axial direction of the first sun axis 11. The outer diameter D2 of the second sun axis 21 is the same as the outer diameter D1 of the first sun axis 11. The other end of the second sun axis 21 in the axial direction is press-fitted and fixed to the inner circumference of the first carrier 14. As a result, the second sun axis 21 rotates around the axis C together with the first carrier 14 in conjunction with the revolution of the first planet roller 13.

The second fixed ring 22 is formed of an annular body, and is arranged concentrically with the axis C of the second sun axis 21 on the radial outer side of the end portion on one side in the axial direction of the second sun axis 21. The second fixed wheel 22 is fixed to the housing body 41 by press-fitting the outer peripheral surface thereof into the large-diameter surface 41b on the inner circumference of the housing body 41. The second fixed wheel 22 is made of the same member as the first fixed wheel 12.

The second planet roller 23 is formed in a cylindrical shape and is arranged between the second sun axis 21 and the second fixed wheel 22. For example, 3 to 4 second planet rollers 23 are arranged at equal intervals in the circumferential direction. The axial width of the second planet roller 23 is slightly smaller than the axial width of the second fixed wheel 22. The second planet roller 23 is made of the same member as the first planet roller 13.

The second planet roller 23 is in rolling contact with the outer peripheral surface of the second sun axis 21 on one side in the axial direction and the inner peripheral surface 22b of the second fixed wheel 22. Further, the diameter of the second planet roller 23 is slightly larger than the radial dimension between the outer circumference of the second sun shaft 21 and the inner circumference of the second fixed ring 22. Therefore, the second planet roller 23 is in contact with the second sun axis 21 and the second fixed wheel 22 with a predetermined pressure contact force. In other words, the second sun axis 21 and the second planet roller 23 are incorporated up to the inner circumference of the second fixed wheel 22.

Traction oil is applied to the contact surface between the second sun axis 21 and the second planet roller 23 and the contact surface between the second planet roller 23 and the second fixed wheel 22. Then, when the second sun axis 21 rotates, the rotational power is transmitted to the second planet roller 23 by the shearing force of the traction oil, and the second planet roller 23 revolves on the inner peripheral surface 22b of the second fixed wheel 22.

The second carrier 24 is made of an annular body, and the outer peripheral surface of the plurality of second planet rollers 23 is arranged on one side in the axial direction so as to face the small diameter surface 41c of the housing 4. A plurality of peripheral holes 24a corresponding to the plurality of second planet rollers 23 are formed on the outer peripheral side of the second carrier 24, and one end of the second support shaft 25 in the axial direction is press-fitted into each peripheral hole 24a. Is fixed.

The second support shaft 25 is formed in a cylindrical shape, and the end portion of the second support shaft 25 on the other side in the axial direction is inserted into the inner circumference of the second planet roller 23 and comes into sliding contact with the inner peripheral surface thereof. Therefore, a slight gap that allows slippage is formed between the outer peripheral surface of the second support shaft 25 and the inner peripheral surface of the second planet roller 23. Therefore, the second planet roller 23 can be rotatably supported by the second support shaft 25 and can move in the axial direction.

The power transmission shaft 5 is formed in a cylindrical shape and is inserted into the mounting hole 41a of the housing body 41. The power transmission shaft 5 is arranged concentrically with the axis C of the second sun axis 21 on one side in the axial direction of the second sun axis 21, and the end portion of the power transmission shaft 5 on the other side in the axial direction is the first. 2 The carrier 24 is press-fitted and fixed to the inner circumference. The power transmission shaft 5 is an output shaft that outputs rotational power that has been input to the first sun shaft 11 and decelerated to the outside.

The axially intermediate portion of the power transmission shaft 5 is rotatably supported by a rolling bearing 7 mounted in the mounting hole 41a. The rolling bearing 7 can roll freely between the outer ring 7a which is press-fitted and fixed to the inner surface of the mounting hole 41a, the inner ring 7b which is press-fitted and fixed to the outer peripheral surface of the power transmission shaft 5, and the outer ring 7a and the inner ring 7b. It is a ball bearing having a plurality of balls (rolling elements) 7c arranged in. As a result, the second carrier 24 is rotatably supported by the housing 4 via the power transmission shaft 5 and the rolling bearing 7. As a result, the power transmission shaft 5 rotates around the axis C together with the second carrier 24 in conjunction with the revolution of the second planet roller 23.

A collar ring 9 is arranged on one side of the second fixed wheel 22 in the axial direction. The collar ring 9 is formed in an annular shape and is sandwiched between the second fixed wheel 22 and the stepped surface 41d of the housing body 41. The outer diameter of the collar ring 9 is the same as or slightly smaller than the large diameter surface 41b of the housing body 41. The inner diameter of the collar ring 9 is smaller than the inner diameter of the second fixed ring 22, and the radial inner end of the collar ring 9 projects radially inward from the inner peripheral surface 22b of the second fixed ring 22. There is. As described above, the second planet roller 23 that rolls on the inner peripheral surface 22b of the second fixed wheel 22 can move in the axial direction with respect to the second support shaft 25, but the collar ring 9 allows the second planet roller 23. The movement of 23 in one axial direction is restricted.

[Composition of ball bearings]
The ball bearing 30 is arranged in the housing 4 on the radial outer side of the first carrier 14, and rotatably supports the first carrier 14. The ball bearings 30 include an outer ring 31 arranged between the first fixed ring 12 and the second fixed ring 22, an inner ring 32 press-fitted and fixed to the outer circumference of the first carrier 14, and an outer ring 31 and an inner ring 32. It has a plurality of balls (rolling bodies) 33 that are rotatably arranged between the two.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG. The outer diameter of the outer ring 31 of the ball bearing 30 is smaller than the diameter of the large diameter surface 41b of the housing body 41. As a result, an annular gap is formed between the outer peripheral surface of the outer ring 31 and the large diameter surface 41b of the housing body 41.
The inner diameter of the outer ring 31 is larger than the inner diameter of the first fixed ring 12 and the inner diameter of the second fixed ring 22. As a result, the end surface 31a on the other side in the axial direction of the outer ring 31 comes into contact with the end surface 12a on the one side in the axial direction of the first fixed ring 12, and the end surface 31b on the one side in the axial direction of the outer ring 31 is in the axial direction of the second fixed ring 22. It is in contact with the end face 22a on the other side.

Therefore, the outer ring 31 is arranged in a state where the end faces 31a and 31b on both sides in the axial direction are in contact with the first fixed ring 12 and the second fixed ring 22, and the movement of the outer ring 31 to both sides in the axial direction is restricted. There is. As a result, the movement of the inner ring 32 arranged via the ball 33 to both sides in the axial direction with respect to the outer ring 31 is restricted, so that the inner ring 32 is press-fitted into the first carrier 14 and the first carrier 14 into which the inner ring 32 has been press-fitted. The movement of the second sun axis 21 to both sides in the axial direction is restricted.

The axial width of the inner ring 32 of the ball bearing 30 is the same as the axial width of the outer ring 31, and the outer diameter of the inner ring 32 is larger than the inner diameter of the first fixed ring 12 and the inner diameter of the second fixed ring 22. Is also small. As a result, the end surface 32a on the other side of the inner ring 32 in the axial direction does not come into contact with the end surface 12a of the first fixed ring 12, and the end surface 32b on the one side in the axial direction of the inner ring 32 contacts the end surface 22a of the second fixed ring 22. There is nothing to do. Therefore, the inner ring 32 is arranged so that the end faces 32a and 32b on both sides in the axial direction are not in contact with the first fixed ring 12 and the second fixed ring 22.

Further, the axial width of the inner ring 32 of the ball bearing 30 is larger than the axial width of the first carrier 14. As a result, when the first planet roller 13 moves to one side in the axial direction with respect to the first support shaft 15, the first planet roller 13 comes into contact with the end surface 32a on the other side in the axial direction of the inner ring 32, and the second planet roller 23 moves to the second support shaft. When it moves to the other side in the axial direction with respect to 25, it comes into contact with the end surface 32b on one side in the axial direction of the inner ring 32. Therefore, the inner ring 32 is arranged so that the end faces 32a and 32b on both sides in the axial direction can come into contact with the first planet roller 13 and the second planet roller 23, whereby the shaft of the first planet roller 13 is arranged. Movement to one side in the direction and movement of the second planet roller 23 to the other side in the axial direction are restricted.

[Power transmission]
In FIG. 1, in the first-stage power transmission mechanism 10, the rotational power of the first sun shaft 11 serving as the input shaft is transmitted to each of the first planet rollers 13 by the shearing force of the traction oil. Then, each of the first planet rollers 13 rotates around the first support shaft 15 and revolves around the first sun axis 11 while rolling on the inner peripheral surface 12b of the first fixed wheel 12. The first carrier 14 rotates around the axis C together with the second sun axis 21. As a result, the rotational power of the first sun shaft 11 of the first stage power transmission mechanism 10 is decelerated and transmitted to the second sun shaft 21 of the second stage power transmission mechanism 20. At that time, since the inner ring 32 of the ball bearing 30 rotates together with the first carrier 14, the power transmission ability to the second sun shaft 21 is not reduced.

In the second-stage power transmission mechanism 20, the rotational power of the second sun shaft 21 is transmitted to each second planet roller 23 by the shearing force of the traction oil. Then, each of the second planet rollers 23 rotates around the second support shaft 25 and revolves around the second sun shaft 21 while rolling on the inner peripheral surface 22b of the second fixed wheel 22. The second carrier 24 rotates around the axis C together with the power transmission shaft 5. As a result, the rotational power of the second sun shaft 21 of the second stage power transmission mechanism 20 is further decelerated and transmitted to the power transmission shaft 5.

According to the multi-stage planetary roller type power transmission device 1 of the present embodiment, the outer ring 31 of the ball bearing 30 is in a state where the end faces 31a and 31b on both sides in the axial direction are in contact with the first fixed wheel 12 and the second fixed wheel 22. Since the inner ring 32 is arranged with respect to the outer ring 31 via the ball 33, the movement of the inner ring 32 to both sides in the axial direction is restricted. As a result, the movement of the first carrier 14 into which the inner ring 32 is press-fitted and the second solar shaft 21 press-fitted into the first carrier 14 in both axial directions is restricted.

Further, when the first planet roller 13 skews and moves to one side in the axial direction with respect to the first support shaft 15, the first planet roller 13 comes into contact with the end surface 32a of the inner ring 32 of the ball bearing 30. The movement of the planetary roller 13 to one side in the axial direction (first carrier 14 side) is restricted. Similarly, when the second planet roller skews and moves to the other side in the axial direction with respect to the second support shaft 25, the second planet roller 23 comes into contact with the end surface 32b of the inner ring 32 of the ball bearing 30. 2 The movement of the planetary roller 23 to the other side in the axial direction (first carrier 14 side) is restricted.

As described above, the movement of the second sun axis 21 to both sides in the axial direction can be restricted only by using a single ball bearing 30, and the first carrier 14 of the first planet roller 13 and the second planet roller 23 can be restricted. Axial movement to the side can be restricted. As a result, the number of parts is reduced compared to the case where the spacer and the two flange wheels are arranged between the pair of fixed wheels and the rolling bearings are arranged on the pair of carriers as in the conventional case, so that the configuration is inexpensive. Axial movement of the first planet roller 13, the second planet roller 23, and the second sun axis 21 can be restricted. As a result, it is possible to suppress a decrease in rotation accuracy and a decrease in power transmission ability.

Further, since the first fixed ring 12 and the second fixed ring 22 are made of the same member and the outer diameter D1 of the first sun shaft 11 and the outer diameter D2 of the second sun shaft 21 are the same, the first fixed wheel The radial position of the 12 is the same as the radial position of the second fixed wheel 22, and the radial position of the first planet roller 13 and the radial position of the second planet roller 23 are the same. As a result, the outer ring 31 of the ball bearing 30 can be easily positioned with respect to the first and second fixed wheels 12, 22 and the first and second fixed wheels 12, 22 and the first and second planetary rollers. The inner ring 32 of the ball bearing 30 can be easily positioned with respect to 13 and 23.

Further, the first fixed wheel 12 and the second fixed wheel 22 are made of the same member, and the first planet roller 13 and the second planet roller 23 are made of the same member. As a result, the first fixed wheel 12 and the second fixed wheel 22 can be shared by the same member, and the first planet roller 13 and the second planet roller 23 can be shared by the same member. The types of parts constituting the planetary roller type power transmission device 1 can be reduced.

[Other]
The embodiments disclosed as described above are exemplary in all respects and are not restrictive. That is, the multi-stage planetary roller type power transmission device of the present invention is not limited to the illustrated form, and may be another form within the scope of the present invention. For example, in the above embodiment, the first sun axis 11 is used as an input axis and the power transmission axis 5 is used as an output axis, but the present invention is not limited to this, and the power transmission axis 5 is used as an input axis and the first sun axis is used. 11 may be used as an output shaft.

In the ball bearing 30 of the above embodiment, the outer rings 32 are made so that the end faces 32a and 32b on both sides of the inner ring 32 in the axial direction are not in contact with the fixed wheels 12 and 22 and are in contact with the planet rollers 13 and 23. The diameter is made smaller than the inner diameters of the fixed wheels 12 and 22, but the diameter is not limited to this. For example, as shown in FIG. 3, when the chamfered portions 12a1, 22a1 are formed inside the end faces 12a, 22a of the fixed rings 12, 22 in the radial direction, the outer diameter of the inner ring 32 is set to the fixed wheels 12, 22. It may be larger than the inner diameter. In this case, if the outer diameter of the inner ring 32 is smaller than the maximum outer diameter of the chamfered portions 12a1, 22a1 (diameter of the outer end in the radial direction), and the inner diameter of the inner ring 32 is smaller than the inner diameter of the fixed rings 12 and 22. Good.

The second fixed wheel 22 of the above embodiment is made of the same member as the first fixed wheel 12, but may be a member different from the first fixed wheel 12. Similarly, the second planet roller 23 of the above embodiment is made of the same member as the first planet roller 13, but may be a member different from the first planet roller 13.

The multi-stage planetary roller type power transmission device of the present invention is not limited to the two-stage planetary roller type power transmission device, and may be a planetary roller type power transmission device having three or more stages. In this case, in the n-stage (n is an integer of 3 or more) planetary roller type power transmission device, if at least one of the carriers from the first stage to the (n-1) stage is rotatably supported. Good.

1: Multi-stage planetary roller type power transmission device 11: 1st sun axis 12: 1st fixed wheel 13: 1st planet roller 14: 1st carrier 21: 2nd sun axis 22: 2nd fixed wheel 23: 2nd planetary roller 24: 2nd carrier 30: Ball bearing 31: Outer ring 31a, 31b: End face 32: Inner ring 32a, 32b: End face 33: Ball C: Axis D1: Outer diameter of the first sun axis D2: Outer diameter of the second sun axis

Claims (3)

The first sun axis and
A first fixed ring arranged concentrically with the axis of the first sun axis on the outer side in the radial direction of the first sun axis.
A plurality of first planetary rollers provided between the first sun axis and the first fixed ring, and
An annular first carrier that is arranged on one side of the plurality of first planet rollers in the axial direction, supports each of the first planet rollers rotatably, and rotates in conjunction with the revolution of the first planet rollers.
A second sun axis whose other end in the axial direction is press-fitted into the inner circumference of the first carrier,
A second fixed ring arranged concentrically with the axis of the second sun axis on the radial outer side of the end on one side in the axial direction of the second sun axis.
A plurality of second planet rollers provided between the second sun axis and the second fixed ring, and
A second carrier, which is arranged on one side in the axial direction of the plurality of second planet rollers, supports each of the second planet rollers rotatably, and rotates in conjunction with the revolution of the second planet rollers. It is a multi-stage planetary roller type power transmission device.
An outer ring arranged between the first fixed ring and the second fixed ring, an inner ring press-fitted into the outer circumference of the first carrier, and a plurality of rollable arrangements between the outer ring and the inner ring. Equipped with ball bearings with balls
The outer ring is arranged in a state where the end faces on both sides in the axial direction are in contact with the first fixed ring and the second fixed ring.
The inner ring has end faces on both sides in the axial direction in a non-contact state with respect to the first fixed ring and the second fixed ring, and can contact the first planet roller and the second planet roller. Multi-stage planetary roller type power transmission device arranged in a state. The outer diameter of the first sun axis and the outer diameter of the second sun axis are the same,
The multi-stage planetary roller type power transmission device according to claim 1, wherein the first fixed wheel and the second fixed wheel are made of the same member. The multi-stage planetary roller type power transmission device according to claim 2, wherein the first planet roller and the second planet roller are made of the same member.

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