JP2010121694A - Friction type planetary power transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make large the variable width of a pressing force which presses elements to each other in a friction type planetary power transmission mechanism. <P>SOLUTION: Four pieces of planetary rollers 122 are arranged around a sun roller 16 so as to contact it and in addition, a ring 128 is arranged around the planetary rollers. The four pieces of planetary rollers 122 are supported on a carrier so that a first arrangement, in which contact points with the ring 128 form a square, and a second arrangement, in which the contact points with the ring 128 form a rectangle, can be taken. The deformation quantity of the ring 128 and a force that acts on the planetary rollers 122 of the ring 128 (pressing force) become larger in the first arrangement of the square shape than in the second arrangement of the rectangular shape. Furthermore, each planetary roller 122 includes a large diameter part 142, which contacts the outside circumferential surface of the sun roller 16, and small diameter parts 143-1, 143-2, which have smaller outer diameters than the large diameter part 142 and contact the inside circumferential surface of the ring 128. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention contacts the central element, the peripheral element disposed around the central element, the outer peripheral surface of the central element, and the inner peripheral surface of the peripheral element, and rotates to transmit torque by friction at the contact point. The present invention relates to a frictional planetary power transmission device that includes a planetary element and a support element that supports the planetary element, and transmits and receives power between the central element, the peripheral element, and the support element.

  The planetary gear (planetary element) of a known planetary gear type power transmission device is a rolling element such as a roller, and the sun gear (center element) and the ring gear (surrounding element) are cylinders with smooth surfaces. A friction type planetary power transmission device that transmits torque is known. The following Patent Document 1 shows a friction type planetary power transmission device as described above. In particular, in the device of this document, the central element and the peripheral element are decentered, and one element of the planetary element is pushed into the narrow space between these elements caused by the decentering, and the elements are pressed against each other. I am raising my power.

JP-A-10-281248

  In the apparatus described in Patent Document 1, the central element and the peripheral element are eccentric, which is a restriction on the apparatus layout. In addition, when the torque acts in the direction in which the planetary element bites into the part where the distance between the central element and the surrounding element is narrow, the pressing force between the elements can be increased, but when the reverse torque is applied, the planetary element is Torque acts in the direction of exclusion from the gap, and the pressing force is reduced.

  Furthermore, the planetary element needs to be located in a portion where the distance between the central element and the surrounding element is narrow, and cannot perform a revolving motion. Therefore, it is not possible to perform operations such as distributing the input torque from the central element to the surrounding elements and the supporting elements that support the planetary elements.

  The above problems are caused by increasing the pressing force between the elements by using a so-called “wedge effect” in which the planetary element is digged into a portion where the distance between the central element and the surrounding element is narrow. The present invention provides a friction type planetary power transmission device that controls the pressing force between elements based on a principle different from the wedge effect. Furthermore, the present invention provides a friction type planetary power transmission device capable of increasing the variable width of the pressing force between elements.

  The friction type planetary power transmission device of the present invention has a plurality of planetary elements that are in contact with the outer peripheral surface of the central element and the inner peripheral surface of the surrounding element that are concentrically arranged to rotate and transmit torque, and the mutual arrangement of these By changing, the pressing force between elements is controlled. The surrounding elements are deformed in response to the reaction force of the pressing force against the planetary elements, and the larger the amount of deformation, the greater the force pressing the elements. By changing the arrangement of the planetary elements, the amount of deformation of the surrounding elements can be changed, and thereby the pressing force can be changed.

  Furthermore, in the present invention, each planetary element includes a large-diameter portion that contacts the outer peripheral surface of the central element, and a small-diameter portion that has an outer diameter smaller than that of the large-diameter portion and contacts the inner peripheral surface of the surrounding element. Thus, without changing the number of planetary elements and the outer diameter of the surrounding elements, the variable width of the arrangement of the planetary elements (the deformation amount of the surrounding elements) can be increased, and the variable width of the pressing force between the elements can be increased. be able to.

  For example, when there are three or more planetary elements, the pressing force can be changed by enabling the arrangement of planetary elements with different perimeter lengths of polygons connecting the contact points of the planetary elements and surrounding elements. Can do. The longer the circumference of this polygon, the greater the deformation of the surrounding elements and the higher the pressing force. In the case where there are two planetary elements, the pressing force becomes the largest when the two are arranged in the diameter direction of the central element, and the pressing force becomes smaller as the distance from this increases. The support element that supports the planetary element supports the planetary element so that the arrangement can be changed as described above. The arrangement in which the pressing force is increased, that is, the arrangement in which the circumference of the polygon is long when there are three or more planetary elements, and the arrangement in the diametrical direction when there are two planetary elements Called arrangement. On the contrary, the arrangement in which the pressing force is reduced is referred to as a second arrangement.

  When the torque to be transmitted is large, the first arrangement can be adopted, and when the torque is small, the second arrangement can be adopted.

  The supporting element supports a part of the planetary element so as to be movable in the circumferential direction with respect to the remaining planetary elements, and the circumferential movement of the planetary element is caused by the transmission torque. It is possible to shift from the second arrangement to the first arrangement.

  When three or more planetary elements are provided, the planetary element has a first group including at least one planetary element and a second group including at least one planetary element other than the first group. When the transmission torque acts in the first direction, the transmission torque enables the first group of planetary elements to move in the circumferential direction with respect to the other planetary elements, whereby the planetary elements are arranged in the second arrangement. To the first arrangement. In addition, when transmission torque acts in the second direction opposite to the first direction, this transmission torque enables the second group of planetary elements to move in the circumferential direction with respect to other planetary elements. This allows the planetary element to transition from the second arrangement to the first arrangement.

  The number of planetary elements can be four. The first group and the second group can be formed by planetary elements on a diagonal line. When the torque in the first direction is applied, the first group moves in the direction of the torque, and when the torque in the second direction opposite to the first direction is applied, the second group is in the reverse direction. It can be moved in the direction of

  The moving planetary element can be biased by the spring element in the direction of the second arrangement.

  When the number of planetary elements is three or more, the first arrangement of planetary elements can be such that the polygon is a regular polygon.

  According to the present invention, the pressing force between elements can be controlled by changing the arrangement of a plurality of planetary elements. Furthermore, according to the present invention, the variable width of the pressing force between the elements can be increased.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

Basic configuration
FIG. 1 is a cross-sectional view of the basic configuration of the frictional planetary power transmission device 10, and FIG. 2 is a cross-sectional view taken along line AA shown in FIG. This basic configuration is a configuration proposed by the applicant in Japanese Patent Application No. 2007-130430. A sun roller shaft 14 is rotatably supported on the case 12 via a bearing 13, and a sun roller 16 is integrally provided at the left end of the sun roller shaft 14 in the figure. The sun roller 16 has a cylindrical shape. A carrier 18 is fixed to the case 12, and the carrier 18 supports a cylindrical planetary roller 22 via a planetary roller shaft 20. As shown in FIG. 2, four planetary rollers 22 are provided around the sun roller 16 so as to come into contact therewith. When it is necessary to distinguish the four planetary rollers, the following description will be made using the symbols 22A, 22B, 22C, and 22D. The planetary roller 22 is rotatably supported on the planetary roller shaft 20 via a needle roller bearing. The planetary roller shaft 20 is movable in the circumferential direction along an arcuate guide groove 24 provided in the carrier 18. The planetary roller shaft 20 is urged toward one end of the guide groove 24 by a spring 26. The direction of biasing by the spring 26 is different for each planetary roller 22. The planetary rollers 22A and 22B are urged clockwise in FIG. 2, and the planetary rollers 22C and 22D are urged counterclockwise. The movement of the planetary roller 22 relative to the carrier will be described in detail later.

  A ring 28 whose inner peripheral surface is in contact with each planetary roller 22 is disposed on the outer side of the planetary roller 22. The ring 28 is fixed to the cap 30, and the ring 30 is integrally provided with the cap 30. The ring side shaft 32 is rotatably supported by the carrier 18 via a bearing 34. The sun roller 16, the ring-side shaft 32, and the ring 28 are arranged concentrically, and the axis of the planetary roller 22 is arranged on a circumference having a common center with this axis. Further, the planetary roller 22 is movable along the guide groove 24 on this circumference.

  The planetary roller 22 contacts the cylindrical outer peripheral surface of the sun roller 16 and the cylindrical inner peripheral surface of the ring 28, and transmits torque by friction at these contact points. The power transmission operation of the friction type planetary power transmission device 10 is basically the same as that of a general planetary gear mechanism. In the planetary gear mechanism, torque transmission is performed by meshing of the gears. Is different by friction.

  When the case 12 is fixed (in a non-rotating state), that is, when the carrier 18 is fixed and the sun roller 16 is rotated, the planetary roller 22 rotates and the ring 28 rotates reversely with respect to the sun roller 16. At this time, the planetary roller shaft 20 is fixed, and the planetary roller 22 does not revolve around the sun roller 16. Further, the rotational speed of the ring 28 is decelerated with respect to the rotational speed of the sun roller 16 by the ratio of the radius of the sun roller outer peripheral surface and the ring inner peripheral surface. In addition, when the ring 28 is fixed, the planetary roller 22 rotates by the rotation of the sun roller 16, but the contact point of the planetary roller 22 with the ring 28 is constrained by the ring 28, so that a revolving motion occurs. As a result, the carrier 18 and the case 12 rotate. Further, if both the carrier 18 and the ring 28 are not fixed, the input from the sun roller 16 can be distributed to the carrier 18 and the ring 28. Although the above is a case where the sun roller 16 is used as an input, the carrier 18 can be used as an input or the ring 28 can be used as an input.

  As described above, in the basic configuration, the relative arrangement of the four planetary rollers 22 can be changed. By changing the arrangement, the pressing force of the planetary roller 22, the ring 28 and the sun roller 16 can be changed. Hereinafter, the relationship between the arrangement of the planetary rollers 22 and the pressing force will be described.

  FIG. 3 is an explanatory diagram of the principle that the pressing force changes. The friction type planetary power transmission device 10 transmits power by friction between elements. For this reason, the ring 28 is interference-fitted to generate a pressing force between the elements. If the ring 28 is a complete rigid body, a complete cylindrical shape can be maintained as shown in FIG. However, in reality, it deforms in response to the tightening reaction force due to the interference fit, and as shown in FIG. 3B, the contact point with the planetary roller 22 bulges outward and deforms into a quadrangle with rounded corners.

  FIG. 3B shows a state in which four planetary rollers 22 are arranged at equal intervals in the circumferential direction, and contact points 36A to 36D between the planetary rollers 22A to 22D and the ring 28 are squares 38 (FIG. It becomes the vertex of d) see). FIG. 3C shows an arrangement in which the equally spaced arrangement is shifted so that the contact points are rectangular. By rotating the two planetary rollers 22C and 22D on one diagonal line counterclockwise from the square arrangement shown in FIG. 3B, the arrangement shown in FIG. 3C is obtained. At this time, the contact points 40A to 40D of the planetary rollers 22 are the vertices of the rectangle 42 (see FIG. 3D).

  The square 38 and the rectangle 42 have the same diagonal length, but the length of the outer periphery, that is, the total length of the four sides is longer for the square and shorter for the rectangle. This corresponds to the amount of extension of the circumference of the ring 28. That is, the amount of elastic deformation of the ring 28 is greater when the contact points are arranged in a square shape than when the contact points are in a rectangular shape. As a result, the pressing force generated between the elements becomes larger than that in the rectangular arrangement. In the rectangles having the same diagonal length, the circumference is the longest when the square is square, and becomes shorter as the rectangle becomes flat. The pressing force between elements also changes accordingly. That is, if the circumference of the quadrangle is increased, the pressing force can be increased, and if it is shortened, the pressing force can be decreased. By using this, the pressing force can be controlled.

  In the above, the two planetary rollers 22 are moved to change the circumference of the quadrangle, but the circumference can be changed even if one is moved. Further, the number of planetary rollers may be three or five or more. In this case, the circumference of the contact point between each planetary roller and the ring is longest when the regular polygon is arranged. Furthermore, it is possible to use two planetary rollers. In this case, when the two planetary rollers are arranged on one diameter of the sun roller, the deformation amount of the ring becomes the largest.

  FIG. 4 shows a model for analyzing a change in pressing force due to the arrangement of the planetary rollers 22A and 22C. For simplicity, the sun roller 16 and the planetary rollers 22A and 22C are handled as rigid bodies. The interval between the two planetary rollers 22A and 22C is an angle a. When the angle a is 90 °, four planetary rollers 22 are arranged in a square as shown in FIG.

  FIG. 5 is an enlarged view of the planetary roller 22C of FIG. The planetary roller 22C has been moved by an angle θ from the square arrangement in FIG. At this time, the contact point 40C between the planetary roller 22C and the ring 28 is shifted from the center O of the sun roller 16 and the straight line m passing through the center point P of the planetary roller 22C. The pressing force Fa acting on the contact point 40C is directed to the point P. That is, a moment around the center O is generated, and this generates a rotational force Na.

  When a clockwise torque Tin in the figure is input to the sun roller 16, this torque Tin acts to move the planetary roller 22C clockwise. When this action exceeds the rotational force Na, the planetary roller 22C starts to move in a direction to reduce the angle θ. That is, when the torque Tin input from the sun roller 16 increases, the four planetary rollers 22 shift from the rectangular arrangement to the square arrangement, and the pressing force increases. That is, when the transmission torque is large and it is necessary to increase the pressing force in order to prevent slippage at the contact point, the pressing force increases autonomously. As a result, when the transmission torque is small, the pressing force can be reduced and the contact surface pressure at the contact point between the elements can be reduced, which is advantageous for improving the durability. In addition, the fact that the pressing force is small means that the amount of deformation of the ring 28 is small, and the energy consumed for the deformation of the ring 28 can be reduced, which is advantageous in improving the transmission efficiency. Further, when a disturbance torque is input, the planetary roller is moved by this torque and the pressing force is increased. Therefore, even if a sudden disturbance torque is input, this can be handled autonomously. Therefore, the occurrence of slip due to disturbance torque is suppressed, which is advantageous in improving durability.

  Returning to FIGS. 1 and 2, the operation of the frictional planetary power transmission device 10 will be described again. As described above, the four planetary rollers 22 are movable in the circumferential direction with respect to the carrier 18. The arrangement of the planetary rollers 22 in FIG. 2 is an arrangement when the transmission torque is low, and corresponds to the state of FIG. The planetary rollers 22A and 22B are located at the right end of the guide groove 24 when viewed from the center of the sun roller 16, and the planetary rollers 22C and 22D are located at the left end of the guide groove 24.

  When the sun roller 16 as the input element rotates clockwise as indicated by the arrow R1, the planetary rollers 22C and 22D move clockwise when the transmission torque exceeds a predetermined value. As a result, the arrangement of the four planetary rollers 22 shifts to the square arrangement shown in FIG. Conversely, when the sun roller 16 rotates counterclockwise as indicated by the arrow R2, the planetary rollers 22A and 22B move counterclockwise, and the four planetary rollers 22 shift to the square arrangement. As described above, when the direction of movement is reversed between the planetary rollers 22A and 22B and the planetary rollers 22C and 22D, the torque increases in response to the torque input in either the forward or reverse direction. The pressing force can be increased.

  In addition, by appropriately setting the characteristics of the spring 26, when the transmission torque is equal to or greater than a predetermined value, the pressing force can be increased as the transmission torque is increased. FIG. 6 is a diagram illustrating an example of the relationship between the input torque and the pressing force. Until the input torque reaches Tb, the initial arrangement of the planetary rollers 22, that is, the rectangular arrangement is maintained. The input torque Tb is a value at which the planetary rollers 22C and 22D begin to move against the aforementioned rotational force Na and the initial biasing force of the spring 26. The input torque Tb can be changed by adjusting the initial biasing force of the spring 26. When the input torque exceeds Tb, the planetary rollers 22C and 22D are positioned so that the force generated by the input torque and the spring force are balanced. If the spring characteristics of the spring 26 are set so that the planetary rollers 22C and 22D reach the right end of the guide groove 24 at the assumed maximum input torque Tmax, the input torque is between the torque Tb and the maximum input torque Tmax. It can be set to increase the pressing force with the increase. The same applies to the reverse torque. As a result, in the range K where the input torque is small, the pressing force is constant, and when the input torque exceeds a predetermined value Tb, the pressing force increases as the input torque increases in the range L up to the maximum input torque. Can be given.

  In this basic configuration, the four planetary rollers 22 are divided into two groups, one group is moved in the circumferential direction in response to the transmission torque in the first direction, and the other group is in the reverse direction. It moved so as to correspond to the transmission torque in the direction of 2. However, one of the four may move corresponding to the transmission torque in the first direction, and the other may correspond to the torque in the second direction. At this time, the remaining two do not move in the circumferential direction for torque in either the forward or reverse direction. Further, as described above, the number of planetary rollers is not limited to four.

  In this basic configuration, the configuration of the planetary roller 22 is changed autonomously from the relationship between the rotational forces Na and Nb, the spring force of the spring 26, and the transmission torque, but a fluid pressure actuator or the like is provided, The arrangement of the planetary rollers 22 can be forcibly changed from the outside.

"Embodiment"
7 and 8 are diagrams showing a schematic configuration of the friction type planetary power transmission device 10 according to the embodiment of the present invention. FIG. 7 is a sectional view of the sun roller 16 as seen from the axial direction. Sectional drawing seen from the direction orthogonal to the axial center of is shown. In the following description of the embodiment, the same reference numerals are given to the same or corresponding configurations as the basic configurations shown in FIGS. 1 to 6, and the configurations that are not described are the same as the basic configurations.

  In the present embodiment, each planetary roller 122 includes a cylindrical large diameter portion 142 and a pair of cylindrical small diameter portions 143-1 and 143-2 having an outer diameter smaller than that of the large diameter portion 142. Is done. When it is necessary to distinguish the four planetary rollers, the description will be made using the reference numerals 122A, 122B, 122C, and 122D. In the example shown in FIGS. 7 and 8, the outer diameter of each planetary roller 122 decreases stepwise from the large diameter portion 142 to the small diameter portion 143-1 (or the small diameter portion 143-2). In each planetary roller 122, the large-diameter portion 142 is disposed between the small-diameter portions 143-1 and 143-2 with respect to the axial direction. The ring 128 includes an annular member 147 and a pair of annular projecting portions 148-1 and 148-2 projecting radially inward from the annular member 147 toward the small diameter portions 143-1 and 143-2 of the planetary rollers 122, respectively. And comprising. The pair of protrusions 148-1 and 148-2 are spaced from each other with respect to the axial direction of the ring 128, and the distance between the protrusions 148-1 and 148-2 with respect to the axial direction is the axial center. It is longer than the length of the large diameter portion 142 in the direction. The distance between the cylindrical outer peripheral surface of the sun roller 16 and the cylindrical inner peripheral surfaces of the protrusions 148-1 and 148-2 of the ring 128 is shorter than the outer diameter of each planetary roller 122 (large diameter portion 142). The distance between the surface and the inner peripheral surface of the annular member 147 is longer than the outer diameter of each planetary roller 122 (large diameter portion 142). In each planetary roller 122, the cylindrical outer peripheral surface of the large diameter portion 142 is the cylindrical outer peripheral surface of the sun roller 16 with a portion of the large diameter portion 142 entering the space formed between the projecting portions 148-1 and 148-2. And the cylindrical outer peripheral surfaces of the small diameter portions 143-1 and 143-2 are in contact with the cylindrical inner peripheral surfaces of the protrusions 148-1 and 148-2 of the ring 128, respectively. Other configurations of the planetary rollers 122A to 122D are the same as the planetary rollers 22A to 22D of the basic configuration, and other configurations of the ring 128 are the same as the ring 28 of the basic configuration. The friction type planetary power transmission device 10 according to this embodiment is obtained by replacing the planetary rollers 22A to 22D and the ring 28 of the basic configuration with planetary rollers 122A to 122D and a ring 128, respectively.

  Also in the present embodiment, by restricting the rotation of the carrier 18, power can be changed and transmitted between the sun roller 16 and the ring 128. In this case, when power is transmitted from the sun roller 16 to the ring 128, the frictional planetary power transmission device 10 functions as a speed reduction mechanism that decelerates and transmits power from the sun roller 16 to the ring 128. On the other hand, when transmitting power from the ring 128 to the sun roller 16, the friction type planetary power transmission device 10 functions as a speed increasing mechanism that transmits power from the ring 128 to the sun roller 16 at an increased speed. In addition, by restricting the rotation of the ring 128, power can be shifted and transmitted between the sun roller 16 and the carrier 18. In this case, when transmitting power from the sun roller 16 to the carrier 18, the friction type planetary power transmission device 10 functions as a speed reduction mechanism, and when transmitting power from the carrier 18 to the sun roller 16, the friction type planetary power transmission device 10. 10 functions as a speed increasing mechanism. Further, by restricting the rotation of the sun roller 16, power can be shifted and transmitted between the carrier 18 and the ring 128. In this case, when transmitting power from the ring 128 to the carrier 18, the friction type planetary power transmission device 10 functions as a speed reduction mechanism, and when transmitting power from the carrier 18 to the ring 128, the friction type planetary power transmission device. 10 functions as a speed increasing mechanism.

  Also in this embodiment, the principle of changing the pressing force between each planetary roller 122, the ring 128, and the sun roller 16 is the same as the basic configuration. That is, some planetary rollers (for example, on one diagonal line) so as to change the perimeter of a polygon (rectangle in the example shown in FIG. 7) connecting the contact points of each planetary roller 122 and the ring 128. Is moved in the circumferential direction with respect to the remaining planet rollers (for example, the other planet rollers 122A and 122B on one diagonal line) and the carrier 18, thereby changing the pressing force. For example, when the sun roller 16 rotates clockwise as indicated by the arrow R1, the planetary rollers 122A and 122B are opposed to the urging force of the spring 26 when the transmission torque increases and exceeds a predetermined value. And move clockwise with respect to the carrier 18. As a result, the arrangement of the four planetary rollers 122 shifts from a rectangular arrangement with a short circumference as shown in FIG. 3 (c) to a square arrangement with a long circumference as shown in FIG. 3 (b). , The pressing force increases. Thereafter, when the transmission torque decreases, the planetary rollers 122C and 122D move counterclockwise with respect to the planetary rollers 122A and 122B and the carrier 18 by the biasing force of the spring 26. Thereby, the arrangement of the four planetary rollers 122 shifts from the square arrangement to the rectangular arrangement, and the pressing force is reduced. On the contrary, when the sun roller 16 rotates counterclockwise as indicated by the arrow R2, the planetary rollers 122A and 122B against the biasing force of the spring 26 against the planetary rollers 122C and 122D and the carrier 18 when the transmission torque increases. By moving counterclockwise, the arrangement of the four planetary rollers 122 shifts from a rectangular arrangement to a square arrangement. Thereafter, when the transmission torque is reduced, the planetary rollers 122A and 122B are moved clockwise with respect to the planetary rollers 122C and 122D and the carrier 18 by the biasing force of the spring 26, so that the four planetary rollers 122 are arranged in a square shape. Move from layout to rectangular layout. Thus, the pressing force can be increased by increasing the length of the circumference of the polygon connecting the contact points between the planetary rollers 122 and the ring 128 with respect to the increase in the transmission torque.

  In the above description, the two planetary rollers 122 are moved to change the circumference of the quadrangle. However, even if one is moved, the circumference can be changed. Further, the number of planetary rollers 122 may be three or five or more. In this case, when the contact point between each planetary roller 122 and the ring 128 is a regular polygon, the circumference is the longest. Furthermore, the number of planetary rollers 122 may be two, and in this case as well, the pressing force can be changed by changing the relative arrangement of the two planetary rollers 122. In this case, when the two planetary rollers 122 are arranged on one diameter of the sun roller 16 (first arrangement), the pressing force (the deformation amount of the ring 128) becomes the largest, and the two planetary rollers By deviating the relative arrangement of 122 from this first arrangement, the pressing force (the amount of deformation of the ring 128) is reduced.

  Further, in the above description, the four planetary rollers 122 are divided into two groups, and one group moves in the circumferential direction corresponding to the transmission torque in the first direction, and the other group is in the reverse direction. It was made to move corresponding to the transmission torque in the second direction. However, one of the four may move corresponding to the transmission torque in the first direction, and the other may correspond to the torque in the second direction. At this time, the remaining two do not move in the circumferential direction for torque in either the forward or reverse direction.

  In the basic configuration described above, in order to increase the variable width of the pressing force between each planetary roller 22 and the ring 28 and the sun roller 16, the circumference of the polygon that connects the contact points between each planetary roller 22 and the ring 28 is changed. The variable width needs to be increased. For this purpose, it is necessary to increase the amount of movement of some planetary rollers (for example, planetary rollers 22C and 22D) in the circumferential direction with respect to other planetary rollers (for example, planetary rollers 22A and 22B). Under the condition that the number of planetary rollers 22 and the outer diameter of the frictional planetary power transmission device 10 (outer diameter of the ring 28) are constant, the outer diameter of the sun roller 16 is increased, and the outer diameter of the planetary roller 22 is decreased. Since the gap between the planetary rollers 22 adjacent in the circumferential direction becomes large, it is possible to increase the amount that some planetary rollers can move in the circumferential direction with respect to other planetary rollers, and increase the variable range of the pressing force. It becomes possible to make it. However, in that case, since the ratio between the outer diameter of the outer peripheral surface of the sun roller 16 and the inner diameter of the inner peripheral surface of the ring 28 changes, the gear ratio of the friction type planetary power transmission device 10 also changes. For example, when constraining the rotation of the ring 28 or constraining the rotation of the carrier 18, the reduction ratio (or speed increase ratio) of the friction type planetary power transmission device 10 is reduced by increasing the outer diameter of the sun roller 16. . On the other hand, in order to increase the speed reduction ratio (or speed increase ratio) of the frictional planetary power transmission device 10, the outer diameter of the sun roller 16 is reduced and the outer diameter of the planetary roller 22 is decreased as shown in FIGS. If it enlarges, the clearance gap between the planetary rollers 22 adjacent to the circumferential direction will become small. As a result, the amount that some planetary rollers can move in the circumferential direction with respect to other planetary rollers decreases, and the variable range of the pressing force decreases. 9 and 10 set the outer diameter of the sun roller 16 and the outer diameter of the planetary roller 22 so that the reduction ratio between the sun roller 16 and the carrier 18 is 6 when the rotation of the ring 28 is restricted. An example is shown. Thus, when a large reduction ratio (or speed increase ratio) is required in the basic configuration, it is difficult to increase the variable range of the pressing force.

  In contrast, in the present embodiment, the large-diameter portion 142 of each planetary roller 122 is in contact with the outer peripheral surface of the sun roller 16, and the small-diameter portions 143-1 and 143-2 of each planetary roller 122 are ring 128 (protruding portion 148-). 1, 148-2) is in contact with the inner peripheral surface. Thus, the gear ratio of the frictional planetary power transmission device 10 is adjusted by adjusting the ratio of the outer diameter of the large diameter portion 142 and the outer diameter of the small diameter portions 143-1 and 143-2 in each planetary roller 122. be able to. Therefore, even if the outer diameter of the sun roller 16 is increased in order to increase the gap between the planetary rollers 122 adjacent in the circumferential direction, the outer diameter of the large diameter portion 142 and the outer diameter of the small diameter portions 143-1 and 143-2 By adjusting the ratio, the target transmission ratio can be obtained. For example, when the rotation of the ring 128 is constrained or the rotation of the carrier 18 is constrained, a large reduction ratio (or speed increase ratio) can be obtained even if the outer diameter of the sun roller 16 is increased. 7 and 8, the outer diameter of the sun roller 16 and the outer diameter of the large-diameter portion 142 are set so that the reduction ratio between the sun roller 16 and the carrier 18 when the rotation of the ring 128 is restricted is 6. And the example which set the outer diameter of the small diameter parts 143-1 and 143-2 is shown. In this embodiment, as shown in FIGS. 7 and 8, the basic number shown in FIGS. 9 and 10 is the same as the number of planetary rollers, the outer diameter of the ring, and the gear ratio (reduction ratio) of the friction type planetary power transmission device. Compared to the configuration, the gap between adjacent planetary rollers 122 can be increased, and some planetary rollers (for example, planetary rollers 122C and 122D) can be compared with other planetary rollers (for example, planetary rollers 122A and 122B). The amount that can be moved in the circumferential direction can be increased.

  As described above, according to the present embodiment, the number of the planetary rollers 122 and the outer diameter of the frictional planetary power transmission device 10 (the outer diameter of the ring 128) are not changed, and the target gear ratio is obtained while the target gear ratio is obtained. The gap between the planetary rollers 122 can be increased. Therefore, the amount that some planetary rollers can move in the circumferential direction with respect to other planetary rollers can be increased, and the variable range of the pressing force can be increased. As a result, even when the change width of the transmission torque is large, the pressing force can be controlled more appropriately according to the transmission torque.

  Further, in the basic configuration, the spring 26 needs to receive a force acting when the planetary roller 22 moves in the circumferential direction with respect to the carrier 18 by the transmission torque. As the transmission torque increases, the force received by the spring 26 also increases. Therefore, it is necessary to increase the elastic coefficient of the spring 26, and the spring 26 is easily increased in size.

  In contrast, in the present embodiment, the shaft center of the sun roller 16 and the ring 128 is obtained while obtaining the target gear ratio without changing the outer diameter of the frictional planetary power transmission device 10 (the outer diameter of the ring 128). The distance (center radius of the planetary roller 122) r from the axis of the planetary roller 122 can be increased. For example, as shown in FIG. 8, the center radius r of the planetary roller is made larger than that of the basic configuration shown in FIG. 10 under the same conditions of the outer diameter of the ring and the gear ratio (reduction ratio) of the friction planetary power transmission device. can do. Since the force received by the spring 26 is expressed by (torque acting on the carrier 18) / (center radius r of the planetary roller 122), the force received by the spring 26 is increased by increasing the center radius r of the planetary roller 122. Can be small. As a result, the elastic coefficient of the spring 26 can be reduced, and the spring 26 can be downsized.

  Next, another configuration example of this embodiment will be described.

  In the configuration example shown in FIG. 11, compared to the configuration examples shown in FIGS. 7 and 8, the ring 128 is divided into two annular members 147-1 and 147-2, and the protrusions 148-1 and 148-2. Project from the annular members 147-1 and 147-2 toward the small diameter portions 143-1 and 143-2 of the planetary rollers 122 inward in the radial direction. The outer diameter of each planetary roller 122 (large diameter portion 142) is larger than the distance between the outer peripheral surface of the sun roller 16 and the inner peripheral surfaces of the annular members 147-1 and 147-2, and the outer peripheral surface of the sun roller 16 and the annular member. It is smaller than the distance with the outer peripheral surface of 147-1, 147-2. In each planetary roller 122, the cylindrical outer peripheral surface of the large diameter portion 142 is the cylindrical outer peripheral surface of the sun roller 16 with a part of the large diameter portion 142 entering the space formed between the annular members 147-1 and 147-2. And the cylindrical outer peripheral surfaces of the small diameter portions 143-1 and 143-2 are in contact with the cylindrical inner peripheral surfaces of the protrusions 148-1 and 148-2 of the ring 128, respectively. FIG. 11 shows the outer diameter of the sun roller 16, the outer diameter of the large diameter portion 142, and the small diameter portion 143-143 so that the reduction ratio between the sun roller 16 and the carrier 18 becomes 6 when the rotation of the ring 128 is restricted. The example which set the outer diameter of 1,143-2 is shown.

  According to the configuration example shown in FIG. 11, compared to the configuration examples shown in FIGS. 7 and 8, without changing the outer diameter of the friction type planetary power transmission device 10 (the outer diameter of the ring 128), the planetary roller 122. Since the center radius r can be further increased, the force received by the spring 26 can be further decreased. As a result, the elastic coefficient of the spring 26 can be further reduced, and the spring 26 can be further reduced in size. Further, according to the configuration example shown in FIG. 11, compared to the configuration examples shown in FIGS. 7 and 8, the sun roller 16 has the same outer diameter of the ring and the gear ratio (reduction ratio) of the friction type planetary power transmission device. Since the outer diameter of the ring and the inner diameter of the ring 128 (projections 148-1 and 148-2) can be increased, the pressing force can be reduced even when the same torque is transmitted. In the configuration example shown in FIG. 11, since the ring 128 is divided into two, it is preferable to restrict the rotation of the ring 128.

  In the configuration example shown in FIG. 12, each planetary roller 122 includes a pair of cylindrical large-diameter portions 142-1 and 142-2 and a circular cylinder having a smaller outer diameter than the large-diameter portions 142-1 and 142-2. A small-diameter portion 143 having a shape. In each planetary roller 122, the small diameter portion 143 is disposed between the large diameter portions 142-1 and 142-2 in the axial direction. The ring 128 includes an annular projecting portion 148 projecting radially inward from the annular member 147 toward the small diameter portion 143 of each planetary roller 122. The distance between the large-diameter portions 142-1 and 142-2 in the axial direction is longer than the length of the protruding portion 148 in the axial direction. The distance between the cylindrical outer peripheral surface of the sun roller 16 and the cylindrical inner peripheral surface of the projecting portion 148 of the ring 128 is shorter than the outer diameter of each planetary roller 122 (large diameter portions 142-1 and 142-2), and is annular with the sun roller 16. The distance from the member 147 is longer than the outer diameter of each planetary roller 122 (large diameter portions 142-1 and 142-2). In each planetary roller 122, the cylindrical outer peripheral surface of the small-diameter portion 143 is in the space between the large-diameter portions 142-1 and 142-2, and the cylindrical outer peripheral surface of the small-diameter portion 143 is The cylindrical outer peripheral surface of the large diameter portions 142-1 and 142-2 is in contact with the cylindrical outer peripheral surface of the sun roller 16.

  In the configuration example shown in FIGS. 7 and 8, the outer peripheral surfaces of the small-diameter portions 143-1 and 143-2 on both sides need to be processed separately, whereas in the configuration example shown in FIG. The outer peripheral surfaces of 142-1 and 142-2 can be processed in the same process. Therefore, according to the configuration example shown in FIG. 12, the processing accuracy of the rolling surface of the planetary roller 122 can be improved as compared with the configuration examples shown in FIGS. On the other hand, in the configuration example shown in FIG. 12, since the outer peripheral surface (rolling surface) of the small diameter portion 143 is not exposed to the outside, it is not easy to secure a lubricating oil path to the outer peripheral surface of the small diameter portion 143. 7 and 8, since the outer peripheral surface of the large diameter portion 142 and the outer peripheral surface of the small diameter portions 143-1 and 143-2 are exposed to the outside, the outer peripheral surface and the small diameter of the large diameter portion 142 are exposed. Lubricating oil can be easily supplied to the outer peripheral surfaces of the parts 143-1 and 143-2. Therefore, according to the configuration example shown in FIGS. 7 and 8, lubrication to each rolling surface is facilitated as compared with the configuration example shown in FIG. 12.

It is sectional drawing of the basic composition of a friction type planetary power transmission device. It is sectional drawing by the AA line of FIG. It is explanatory drawing of the principle from which pressing force changes. It is a figure which shows a FEM analysis model. It is explanatory drawing of the generation principle of rotational force Na. It is a figure which shows an example of the relationship between input torque and pressing force. It is sectional drawing which shows schematic structure of the friction type planetary power transmission device which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the friction type planetary power transmission device which concerns on embodiment of this invention. It is sectional drawing of the basic composition of a friction type planetary power transmission device. It is sectional drawing of the basic composition of a friction type planetary power transmission device. It is sectional drawing which shows the other schematic structure of the friction type planetary power transmission device which concerns on embodiment of this invention. It is sectional drawing which shows the other schematic structure of the friction type planetary power transmission device which concerns on embodiment of this invention.

Explanation of symbols

  10 friction type planetary power transmission device, 16 sun roller (center element), 18 carrier (support element), 22, 122 planet roller (planet element), 24 guide groove, 26 spring (spring element), 28, 128 ring (surrounding element) ), 36, 40 Contact point, 142, 142-1, 142-2 Large diameter portion, 143, 143-1, 143-2 Small diameter portion, 147, 147-1, 147-2 Annular member, 148, 148-1 , 148-2 Protruding part.

Claims (8)

A central element having an outer peripheral surface with a circular cross section;
A peripheral element having an inner peripheral surface that is concentric with the outer peripheral surface of the central element and has a circular cross-section facing the outer peripheral surface;
At least three planetary elements that contact the outer peripheral surface of the central element and the inner peripheral surface of the surrounding element, rotate and transmit torque by friction at the contact point;
A supporting element for supporting each planetary element with a predetermined relative relationship on a circumference concentric with the outer peripheral surface of the central element;
Including a friction type planetary power transmission device,
The supporting element can support the planetary element in at least two arrangements having different perimeter lengths of a polygon connecting the contact points of each planetary element and the surrounding element,
Each planet element
A large diameter portion in contact with the outer peripheral surface of the central element;
A small-diameter portion that has an outer diameter smaller than that of the large-diameter portion and that contacts the inner peripheral surface of the surrounding element;
including,
Friction type planetary power transmission device. It is a friction type planetary power transmission device according to claim 1,
The support element supports each planetary element in a first arrangement in which the circumference of the polygon becomes long when the transmission torque of the transmission device is large, and when the transmission torque is small, Support in a second arrangement that reduces the perimeter,
Friction type planetary power transmission device. It is a friction type planetary power transmission device according to claim 2,
The supporting element supports a part of the planetary element so as to be movable in the circumferential direction with respect to the remaining planetary elements. When the planetary element is moved in the circumferential direction by the transmission torque and the transmission torque increases, the second arrangement To the first arrangement,
Friction type planetary power transmission device. It is a friction type planetary power transmission device according to claim 2,
The planetary element has a first group including at least one planetary element and a second group including at least one planetary element other than the first group,
When the transmission torque acts in the first direction, the support element supports the first group of planetary elements movably in the circumferential direction with respect to the other planetary elements by the transmission torque. To move the planetary element from the second configuration to the first configuration,
The support element can also move the second group of planetary elements in the circumferential direction with respect to other planetary elements when the transmission torque acts in a second direction opposite to the first direction. And the planetary element is shifted from the second arrangement to the first arrangement by this circumferential movement.
Friction type planetary power transmission device. The friction type planetary power transmission device according to claim 4,
The number of planetary elements is four, and the first group and the second group are formed by planetary elements arranged on a common diagonal of the quadrilateral polygon.
Friction type planetary power transmission device. The friction type planetary power transmission device according to any one of claims 3 to 5,
The planetary element supported so as to be movable in the circumferential direction has a spring element that urges the planetary element in the direction of the second arrangement.
Friction type planetary power transmission device.   The friction type planetary power transmission device according to any one of claims 2 to 6, wherein the polygon is a regular polygon when the planetary element is in the first arrangement. . A central element having an outer peripheral surface with a circular cross section;
A peripheral element having an inner peripheral surface that is concentric with the outer peripheral surface of the central element and has a circular cross-section facing the outer peripheral surface;
Two planetary elements that contact the outer peripheral surface of the central element and the inner peripheral surface of the surrounding element, rotate and transmit torque by friction at the contact point;
A supporting element for supporting each planetary element with a predetermined relative relationship on a circumference concentric with the outer peripheral surface of the central element;
Including a friction type planetary power transmission device,
The supporting element can support two planetary elements in a first arrangement in which the outer peripheral surface of the central element is arranged on one diameter and in a second arrangement that is shifted from the first arrangement.
Each planet element
A large diameter portion in contact with the outer peripheral surface of the central element;
A small-diameter portion that has an outer diameter smaller than that of the large-diameter portion and that contacts the inner peripheral surface of the surrounding element;
including,
Friction type planetary power transmission device.

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