JP2014040892A - Frictional roller type transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frictional roller type transmission having high transmitting efficiency and realizing a structure to easily ensure durability, by preventing rolling contact portions of peripheral faces of rollers 12b, 13b and 27 from having surface pressures largely different from each other regardless of difference in unevenness in a circumferential direction, of an outer peripheral face of a sun roller 12b and an inner peripheral face of the circular roller 13b.SOLUTION: With respect to cross-sectional shapes of rollers 12b, 13b and 27, a combination of the cross-sectional shape of an outer peripheral face of a sun roller 12b and the cross-sectional shape of outer peripheral face of each of intermediate rollers 27 and 27 is determined to reduce surface pressure of a rolling contact portion, in comparison with a combination of the cross-sectional shape of the outer peripheral face of each of the intermediate rollers 27 and 27, and the cross-sectional shape of an inner peripheral face of a circular roller 13b. A difference in generated surface pressures is canceled on the basis of unevenness in a circumferential direction.

Description

  The present invention relates to an improvement in a friction roller type transmission that transmits torque from an electric motor to driving wheels in a state where it is incorporated in a driving system of an electric vehicle, for example. In addition, although it is thought that the friction roller type transmission of this invention is often used as a reduction gear which decelerates rotational speed, increasing torque, it does not prevent using as a speed increaser.

  In response to the recent trend of reducing fossil fuel consumption, research on electric vehicles has progressed and some have been implemented. Unlike an internal combustion engine (engine) that moves by directly burning fossil fuel, an electric motor that is a power source of an electric vehicle is preferable for an automobile in terms of output shaft torque and rotational speed characteristics (generally at startup) Therefore, it is not always necessary to provide a transmission such as a general automobile using an internal combustion engine as a drive source. However, even in the case of an electric vehicle, acceleration performance and high speed performance can be improved by providing a transmission. Specifically, by providing a transmission, the relationship between the traveling speed and acceleration of the vehicle can be made smooth, similar to a car equipped with a gasoline engine. This point will be described with reference to FIG.

  For example, when a power transmission device having a large reduction ratio is provided between an output shaft of an electric motor that is a drive source of an electric vehicle and an input portion of a differential gear connected to the drive wheel, the acceleration (G) of the electric vehicle And the traveling speed (km / h) are such that the left half of the solid line a in FIG. In other words, acceleration performance at low speed is excellent, but high-speed running is not possible. On the other hand, when a power transmission device with a small reduction ratio is provided in the intermediate portion, the relationship is such that the chain line c in FIG. 7 and the right half of the solid line a are continuous. That is, high-speed travel is possible, but acceleration performance at low speed is impaired. On the other hand, if a transmission is provided between the output shaft and the input unit and the reduction ratio of the transmission is changed according to the vehicle speed, the left half part and the right half part of the solid line a are made continuous. The following characteristics can be obtained. This characteristic is almost the same as that of a gasoline engine vehicle having the same level of output as shown by the broken line d in FIG. 7, and it can be seen that the same performance as that of a gasoline engine vehicle can be obtained with respect to acceleration performance and high speed performance.

  FIG. 8 shows a drive device for an electric vehicle that has been considered in view of such circumstances (Japanese Patent Application No. 2011-250531). The drive device for an electric vehicle according to the prior invention includes an electric motor 1 for driving a vehicle, a friction roller type speed reducer 2, a transmission 3, and a rotation transmission device 4. The input shaft 5 of the friction roller type reduction gear 2 and the output shaft 6 of the electric motor 1 for driving the vehicle are arranged concentrically with each other so that torque can be transmitted. An output shaft 19 (see FIG. 9 to be described later) of the friction roller type speed reducer 2 is disposed concentrically with the drive side rotating shaft 7 of the transmission 3 so as to be able to transmit torque.

The transmission 3 is provided with a pair of gear transmission mechanisms 9a and 9b having different reduction ratios between the driving side rotating shaft 7 and the driven side rotating shaft 8. Then, by switching between the pair of clutch mechanisms 10a and 10b, only one of the gear transmission mechanisms 9a (9b) is allowed to transmit power so that the drive side rotary shaft 7 and the driven side rotary shaft 8 can be transmitted. The reduction ratio between and can be converted into two steps of high and low.
Further, the rotation transmission device 4 is a general gear transmission mechanism in which a plurality of gears are combined. The rotation transmission device 4 transmits the rotation of the driven side rotation shaft 8 to the input portion of the differential gear 11 and a pair of left and right drive wheels. Is driven to rotate.

  For example, the friction roller type speed reducer 2 described in Patent Document 1 can be used. FIG. 9 shows the friction roller type speed reducer 2 described in Patent Document 1. The friction roller type speed reducer 2 includes an input shaft 5, an output shaft 19, a sun roller 12, an annular roller 13, a plurality of planetary rollers 14 and 14, and a loading cam device 15. Of these, the sun roller 12 is concentrically arranged with a pair of sun roller elements 16a and 16b divided in the axial direction around the input shaft 5 with a gap interposed between the tip surfaces thereof. In addition, one of the sun roller elements 16a is arranged so as to be rotatable relative to the input shaft 5. The planetary rollers 14, 14 are rotatably supported around the planetary shafts 17, 17, and the outer peripheral surfaces thereof are the outer peripheral surface of the sun roller 12 and the inner peripheral surface of the annular roller 13. Rolling contact. The base end portions of the planetary shafts 17 and 17 are coupled and fixed to the base end portion of the output shaft 19 via a carrier 18.

  Further, the loading cam device 15 is provided between one sun roller element 16a and the input shaft 5, and the one sun roller element 16a is replaced with the other sun roller as the input shaft 5 rotates. The sun roller 12 composed of both the sun roller elements 16a and 16b is rotationally driven while being pressed toward the element 16b. For this purpose, a support ring 21 is locked to a middle portion of the input shaft 5 by a retaining ring 20, and the support ring 21 and the one sun roller element 16 a are sequentially arranged from the support ring 21 side. A disc spring 22, a cam plate 23, and a plurality of balls 24, 24 are provided. Then, the driven cam surfaces 25 and 25 and the driving cam surface 26 are respectively provided at a plurality of circumferential positions on the base end surface of the one sun roller element 16a and the one side surface of the cam plate 23, which face each other. , 26 are provided. Each of the cam surfaces 25 and 26 has a shape in which the depth in the axial direction is deepest in the central portion in the circumferential direction, and gradually becomes shallower toward both ends.

  In such a loading cam device 15, when the input shaft 5 is stopped, the balls 24, 24 are deepest on the cam surfaces 25, 26 as shown in FIG. Located in the part. In this state, the one sun roller element 16a is pressed toward the other sun roller element 16b by the elasticity of the disc spring 22. On the other hand, when the input shaft 5 rotates, the balls 24 and 24 move to shallow portions of the cam surfaces 25 and 26 as shown in FIG. And the space | interval of said one sun roller element 16a and the said cam board 23 is expanded, and said one sun roller element 16a is pressed toward the said other sun roller element 16b. As a result, the one sun roller element 16a is generated by the elasticity of the disc spring 22 and the balls 24 and 24 riding on the cam surfaces 25 and 26 toward the other sun roller element 16b. It is driven to rotate while being pressed by the larger force of the thrust to be applied.

  During operation of the friction roller type speed reducer 2 as described above, the outer circumferential surface of each of the planetary rollers 14, 14, the outer circumferential surface of the sun roller 12, and the annular shape are generated by the axial thrust generated by the loading cam device 15. The surface pressure of the rolling contact portion with the inner peripheral surface of the roller 13 increases. This surface pressure increases according to the magnitude of torque to be transmitted between the input shaft 5 and the output shaft 19. When the input shaft 5 is rotated in this state, the rotation is transmitted from the sun roller 12 to the planetary rollers 14, 14, and the planetary rollers 14, 14 are rotating around the sun roller 12. Revolve. Therefore, the revolving motion of each of the planetary rollers 14 and 14 is taken out by the output shaft 19 through the carrier 18.

If the friction roller type speed reducer 2 is arranged between the vehicle driving electric motor 1 and the transmission 3 as in the electric vehicle driving device shown in FIG. 8, the electric energy can be used efficiently. Even if a small and high rotation type (for example, the maximum rotation speed is about 30,000 min ⁻¹ ) is used as the vehicle driving electric motor 1, vibration and noise during operation can be suppressed. That is, since the friction roller type speed reducer 2 is used as the first stage speed reducer, it is possible to suppress the occurrence of vibrations at the high speed rotating portion. The rotational speeds of the transmission 3 and the rotation transmission device 4, each of which is a gear transmission mechanism, are approximately the same as the driving speed of a transmission portion of a vehicle equipped with a general gasoline engine (up to several thousand min ⁻¹ Therefore, no unpleasant vibration or noise is generated in any part.

  In the friction roller type speed reducer 2 shown in FIG. 9 described above, the annular roller 13 is fixed, and the intermediate rollers are moved to the planetary rollers 14, 14, so that the planetary rollers 14, 14 revolve. Is taken out through the carrier 18 as a decelerated output. On the other hand, there is a structure in which the intermediate roller can only rotate and the annular roller is rotated to transmit power. For example, although not disclosed, the Japanese Patent Application No. 2011-250531 discloses a friction roller type speed reducer 2a having a structure for extracting power from an annular roller as shown in FIG. Since the present invention can be implemented with the structure shown in FIG. 12, the structure shown in FIG. 12 will be briefly described.

  In the friction roller type speed reducer 2a shown in FIG. 12, the sun roller 12a is rotationally driven by the input shaft 5a, and the rotation of the sun roller 12a is transmitted to the annular roller 13a via a plurality of intermediate rollers 27 and 27. The rotation of the annular roller 13a is taken out from the output shaft 19a. Each of the intermediate rollers 27 and 27 rotates around the rotation shafts 28 and 28 provided at the center thereof, but does not revolve around the sun roller 12a. The sun roller 12a is formed by concentrically combining a pair of sun roller elements 16c and 16c having the same shape, and the loading cam device 15a is provided at a position sandwiching both the sun roller elements 16c and 16c from both sides in the axial direction. , 15a, and the two sun roller elements 16c, 16c are driven to rotate in the same direction while being pressed toward each other as the input shaft 5a rotates. Each component described above is housed in a stepped cylindrical housing 29.

  Further, the annular roller 13a is disposed concentrically with the sun roller 12a in the peripheral portion of the sun roller 12a at the axially intermediate portion of the housing 29. The inner peripheral surface of the annular roller 13a is a cylindrical surface whose inner diameter does not change in the axial direction, and the annular roller 13a and the base end portion of the output shaft 19a are connected by a connecting portion 30 having an L-shaped cross section.

  Further, the intermediate rollers 27 and 27 can freely rotate (rotate) around the rotation shafts 28 and 28 in an annular space between the inner peripheral surface of the annular roller 13a and the sun roller 12a. In addition, the annular roller 13a and the sun roller 12a are installed so as to be slightly displaceable in the radial direction. Further, the outer peripheral surfaces of the intermediate rollers 27 and 27 have the axial intermediate portion as a simple cylindrical surface 31 and the axially opposite side portions at the same angle in the same direction as the outer peripheral surfaces of the solar roller elements 16c and 16c. Inclined partial conical convex surfaces 32 and 32 are provided.

  When the input shaft 5a is rotationally driven by an electric motor during the operation of the friction roller type speed reducer 2a of the prior invention configured as described above, both the sun roller elements 16c, 16c are both loaded cam devices 15a, 15a. By the action of the above, while being pressed toward each other, they rotate in the same direction as the input shaft 5a at the same speed. Then, the rotation of the sun roller 12a constituted by the both sun roller elements 16c and 16c is transmitted to the annular roller 13a through the intermediate rollers 27 and 27 and is taken out from the output shaft 19a.

  In the case of a friction roller type transmission comprising a combination of a sun roller, an annular roller, and a plurality of intermediate rollers (planetary rollers), unless otherwise devised, the outer circumferential surface of the sun roller and the outer circumferential surface of each intermediate roller roll. There is a large difference between the surface pressure of the inner diameter side traction portion that is the contact portion and the surface pressure of the outer diameter side traction portion that is the rolling contact portion between the outer peripheral surface of each intermediate roller and the inner peripheral surface of the annular roller. Produce. Specifically, the surface pressure of the inner diameter side traction portion is significantly higher than the surface pressure of the outer diameter side traction portion. The reason why such a difference occurs is that the shape of the outer peripheral surface of the sun roller in the circumferential direction is a convex arc, whereas the shape of the inner peripheral surface of the annular roller in the circumferential direction is a concave arc. It is. For this reason, if there is a large difference in the surface pressure of each traction part, not only can the transmission efficiency in each traction part be properly regulated, but also the rolling fatigue life of the outer peripheral surface of the sun roller can be reduced. It becomes difficult to secure.

JP 2004-116670 A

  In view of the circumstances as described above, the present invention is based on the difference in unevenness in the circumferential direction between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller, and the outer peripheral surface of the sun roller and the outer peripheral surface of each intermediate roller. Reduce or reduce the difference between the surface pressure of the inner diameter side traction portion that is the rolling contact portion and the surface pressure of the outer diameter side traction portion that is the rolling contact portion between the outer peripheral surface of each intermediate roller and the inner peripheral surface of the annular roller. The invention was invented to realize a structure in which good transmission efficiency can be easily obtained, and durability can be easily secured.

The friction roller type transmission of the present invention includes an input shaft and an output shaft, a sun roller, an annular roller, and a plurality of intermediate rollers.
Each of these intermediate rollers is installed in an annular space between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller so as to be able to rotate at least. And in contact with the inner peripheral surface of the annular roller.
Further, the sun roller is composed of a pair of sun roller elements that are divided into two in the axial direction. These sun roller elements are pressed in the direction of approaching each other at least during power transmission, and the same in the same direction. Rotates at speed.
The input shaft and the output shaft can rotate relative to each other, and are arranged concentrically with the sun roller and the annular roller. The input shaft and the output shaft are coupled to two different elements to two types of elements selected from the supporting members that rotate together.

In particular, in the friction roller transmission of the present invention, regarding the cross-sectional shape of the peripheral surfaces of the rollers that are in rolling contact with each other with respect to a virtual plane including the central axis of each of the rollers, The combination of the cross-sectional shape and the cross-sectional shape of the outer peripheral surface of each intermediate roller is different from the combination of the cross-sectional shape of the outer peripheral surface of each intermediate roller and the cross-sectional shape of the inner peripheral surface of the annular roller. It is set as the combination which makes the surface pressure of the rolling contact part of surfaces low.
And the surface pressure of the rolling contact portion between the outer peripheral surface of the sun roller and the outer peripheral surface of each of the intermediate rollers based on the difference in irregularities in the circumferential direction between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller The difference between the surface pressure of the rolling contact portion between the outer peripheral surface of each intermediate roller and the inner peripheral surface of the annular roller is reduced or eliminated.

When carrying out the present invention as described above, specifically, the cross-sectional shape of the outer peripheral surface of each of the intermediate rollers is a partially arcuate convex arc as in the invention described in claim 2.
Moreover, let the cross-sectional shape of the outer peripheral surface of the said both sun roller element be a concave arc of a partial circular arc shape.
Furthermore, the cross-sectional shape of the inner peripheral surface of the annular roller is a straight line parallel to the central axis.

Alternatively, as in the invention described in claim 3, the cross-sectional shape of the outer peripheral surface of each intermediate roller is a convex arc having a partial arc shape.
Moreover, the cross-sectional shape of the outer peripheral surfaces of the two sun roller elements is a straight line that is inclined in a direction approaching the central axis as it approaches each other.
Furthermore, the cross-sectional shape of the inner peripheral surface of the annular roller is a partially arcuate convex arc.

According to the friction roller type transmission of the present invention configured as described above, the surface pressure of the inner diameter side traction portion which is a rolling contact portion between the outer peripheral surface of the sun roller and the outer peripheral surface of each intermediate roller, and each of these intermediate rollers The difference between the surface pressure of the outer diameter side traction portion which is the rolling contact portion between the outer peripheral surface of the annular roller and the inner peripheral surface of the annular roller can be reduced or eliminated.
That is, in the case of the present invention, since the cross-sectional shape of the peripheral surface of each roller is devised, based on the unevenness in the circumferential direction between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller. The difference between the surface pressures of the inner diameter side and outer diameter side traction portions can be offset.
For this reason, in any of these traction sections, the surface pressure is kept within an appropriate range, the transmission efficiency of the friction roller type transmission can be improved, and the rolling fatigue life of the outer peripheral surface of the sun roller can be increased. It is possible to ensure the durability of the friction roller type transmission.

BRIEF DESCRIPTION OF THE DRAWINGS The principal part schematic side view of the friction roller type transmission which shows the 1st example of embodiment of this invention. WW sectional drawing of FIG. The principal part schematic side view of the friction roller type transmission which shows the 2nd example of embodiment of this invention. XX sectional drawing of FIG. The figure similar to FIG. 2 for demonstrating one example of a specific dimension regarding the 1st example of embodiment. The figure similar to FIG. 4 for demonstrating one example of a specific dimension regarding the 2nd example of embodiment. The diagram for demonstrating the effect by incorporating a transmission into the drive device for electric vehicles. The perspective view of the drive device for electric vehicles which concerns on a prior invention. Sectional drawing which shows an example of the friction roller type reduction gear conventionally known. FIG. 10 is an enlarged YY sectional view of FIG. 9. FIG. 11 is an enlarged ZZ sectional view of FIG. 10. Sectional drawing of the friction roller type reduction gear which concerns on a prior invention.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to claims 1 and 2. The friction roller type speed reducer 2b of the present example has a convex curved surface 33 in which the cross-sectional shape of the outer peripheral surface of each intermediate roller 27, 27 with respect to a virtual plane including the central axis of each intermediate roller 27, 27 is a partially convex arc shape. It is said. The inner peripheral surface of the annular roller 13b is a cylindrical surface whose inner diameter does not change in the axial direction. Further, the outer peripheral surface of the pair of sun roller elements 16d and 16d constituting the sun roller 12b is a concavely curved surface in which a cross-sectional shape with respect to a virtual plane including the central axis of both the sun roller elements 16d and 16d is a partially concave arc shape. 34, 34. The radius of curvature of the cross-sectional shape of each of the concave curved surfaces 34, 34 is slightly larger than the radius of curvature of the cross-sectional shape of each of the convex curved surfaces 33, 33, which is the outer peripheral surface of each of the intermediate rollers 27, 27. The convex curved surfaces 33 and 33 that are outer peripheral surfaces of the intermediate rollers 27 and 27, the inner peripheral surface of the annular roller 13b, and the biconcave curved surface 34 that is the outer peripheral surfaces of the sun roller elements 16d and 16d. , 34 are in rolling contact with each other.

  As described above, in the case of the friction roller type transmission 2b of this example, the outer periphery of each of the intermediate rollers 27 and 27 is related to the sectional shape of each of the rollers 12b, 13b, and 27 with respect to the virtual plane including the respective central axes. The rolling contact portion between the surface and the inner peripheral surface of the annular roller 13b is in a contact state between the convex arc and the straight line, and the rolling contact portion between the outer peripheral surface of each of the intermediate rollers 27 and 27 and the outer peripheral surface of the sun roller 12b. Is a contact state between the convex arc and the concave arc. Therefore, as far as the axial direction appearing as the cross-sectional shape is concerned, the contact area between the outer peripheral surfaces of the sun roller elements 16d and 16d and the outer peripheral surfaces of the intermediate rollers 27 and 27 is the outer periphery of the intermediate rollers 27 and 27. The contact area between the surface and the inner peripheral surface of the annular roller 13b tends to be larger. On the other hand, when viewed in the circumferential direction, the contact area between the outer peripheral surfaces of the solar roller elements 16d and 16d and the outer peripheral surfaces of the intermediate rollers 27 and 27 is the outer peripheral surface of the intermediate rollers 27 and 27. And the contact area with the inner peripheral surface of the annular roller 13b tends to be narrower. In this way, the tendency of the area of the rolling contact portion to change is reversed between the axial direction and the circumferential direction. For this reason, the outer peripheral surface of the sun roller 12b and the inner peripheral surface of the annular roller 13b, which are generated based on the difference in irregularities in the circumferential direction between the outer peripheral surface of the sun roller 12b and the inner peripheral surface of the annular roller 13b. The difference in surface pressure between the rolling contact portions (inner diameter side and outer diameter side traction portions) can be offset.

As a result, in addition to being able to keep the surface pressure within an appropriate range and improving the transmission efficiency of the friction roller type speed reducer 2b for each of the inner diameter side and outer diameter side traction portions, The rolling fatigue life of the outer peripheral surface of the roller 12b can be secured, and the durability of the friction roller type speed reducer 2b can be easily secured.
Since the configuration and operation of the other parts are the same as those of the conventional structure shown in FIG. 9 or the structure of the prior invention shown in FIG. 12, overlapping illustrations and descriptions are omitted.

[Second Example of Embodiment]
3 to 4 show a second example of an embodiment of the present invention corresponding to claims 1 and 3. Also in the case of the friction roller type speed reducer 2c of this example, the outer peripheral surfaces of the intermediate rollers 27 and 27 are convex curved surfaces 33a and 33a whose sectional shape is a partial arc. The curvature radii of the cross-sectional shapes of the convex curved surfaces 33a and 33a are slightly larger than the curvature radii of the cross-sectional shapes of the convex curved surfaces 33 and 33 (see FIG. 2) of the first example of the embodiment described above.
The outer peripheral surfaces of the pair of sun roller elements 16e and 16e constituting the sun roller 12c are partially conical convex surfaces 35 and 35 that are inclined in a direction in which the outer diameter decreases as they approach each other. That is, the cross-sectional shape of the outer peripheral surfaces of the sun roller elements 16e and 16e is a straight line that is inclined in a direction approaching the central axis toward the inner end surfaces facing each other.
Furthermore, the inner peripheral surface of the annular roller 13c is a convex curved surface 36 whose sectional shape is a convex arc having a partial arc shape.
Also in the case of the friction roller type speed reducer 2c of this example configured as described above, each rolling contact is generated based on the difference in unevenness in the circumferential direction between the outer peripheral surface of the sun roller 12c and the inner peripheral surface of the annular roller 13c. The difference in surface pressure of the part can be offset.

With respect to the structure of the first example of the embodiment shown in FIGS. 1 and 2 described above, an example of specific dimensions will be described with reference to FIG.
The dimensions of each part shown in FIG. 5 are regulated as follows.
Diameter D _s of rolling contact portion between outer peripheral surface of sun roller 12b and outer peripheral surface of each intermediate roller 27, 27: 32.0 mm
Curvature radius R _s of the cross-sectional shape of the outer peripheral surface of both sun roller elements 16d, 16d: 25 mm
Diameter D _ps of each of the intermediate rollers 27 and 27 at a rolling contact portion between the outer peripheral surface of the sun roller 12b and the outer peripheral surface of each of the intermediate rollers 27 and 27: 52 mm
Curvature radius R _p of the cross-sectional shape of the outer peripheral surface of each of the intermediate rollers 27, 27: 22 mm
The maximum diameter D _{pr of} each of these intermediate rollers 27, 27: 52.5 mm
Inside diameter _D r of the annular roller 13b: 136.5mm
Inclination angle α of the tangent to each surface at the center of the rolling contact portion between the outer peripheral surface of the sun roller 12b and the outer peripheral surfaces of the intermediate rollers 27, 27 with respect to the central axis of the sun roller 12b: 8 °

Under the above conditions, the normal force of the rolling contact portion between the outer peripheral surface of the sun roller 12b and the outer peripheral surfaces of the intermediate rollers 27 and 27 is 4941N, and the outer peripheral surface of the intermediate rollers 27 and 27 and the annular roller are Assuming that the pressing force of the loading cam device is adjusted so that the normal force related to the rolling contact portion with the inner peripheral surface of 13c is 9786 N, the surface pressure of each rolling contact portion is as follows. become.
Surface pressure of rolling contact portion (inner diameter side traction portion) between outer peripheral surface of sun roller 12b and outer peripheral surface of each intermediate roller 27, 27: 3.01 GPa
Surface pressure of the rolling contact portion (outer diameter side traction portion) between the outer peripheral surface of each of the intermediate rollers 27 and 27 and the inner peripheral surface of the annular roller 13c: 3.01 GPa
As is clear from the above, with the structure of the first example of the above-described embodiment, the surface pressure of each rolling contact portion can be regulated almost equally by appropriately regulating the dimensions of each portion.

Regarding the structure of the second example of the embodiment shown in FIGS. 3 to 4 described above, an example of specific dimensions will be described with reference to FIG.
The dimensions of the parts shown in FIG. 6 are regulated as follows.
Diameter D _s of rolling contact between the outer peripheral surface of the sun roller 12c and the outer peripheral surface of each intermediate roller 27, 27: 33.4 mm
Diameter D _ps of each of the intermediate rollers 27 and 27 at the rolling contact portion between the outer peripheral surface of the sun roller 12b and the outer peripheral surface of each of the intermediate rollers 27 and 27: 51.0 mm
Curvature radius R _p of the cross-sectional shape of the outer peripheral surface of each intermediate roller 27, 27: 57.5 mm
The maximum diameter D _{pr of} each of these intermediate rollers 27, 27: 52.1 mm
Inside diameter _D r of the annular roller 13c: 136.5mm
The curvature radius Rr of the cross-sectional shape of the convex curved surface 36 which is the inner peripheral surface of the annular roller 13c: 40 mm
Inclination angle α of the outer peripheral surface of the pair of sun roller elements 16e, 16e with respect to the central axis of both the sun roller elements 16e, 16e: 8 °

Under the above conditions, the normal force of the rolling contact portion between the outer peripheral surface of the sun roller 12c and the outer peripheral surfaces of the intermediate rollers 27 and 27 is 4941N, and the outer peripheral surface of the intermediate rollers 27 and 27 and the annular roller Assuming that the pressing force of the loading cam device is adjusted so that the normal force related to the rolling contact portion with the inner peripheral surface of 13c is 9786 N, the surface pressure of each rolling contact portion is as follows. become.
Surface pressure of a rolling contact portion (inner diameter side traction portion) between the outer peripheral surface of the sun roller 12b and the outer peripheral surfaces of the intermediate rollers 27 and 27: 3.0 GPa
Surface pressure of the rolling contact portion (outer diameter side traction portion) between the outer peripheral surface of each of the intermediate rollers 27 and 27 and the inner peripheral surface of the annular roller 13c: 2.98 Pa
As is apparent from the above, even in the structure of the second example of the above-described embodiment, the surface pressure of each rolling contact portion can be regulated almost uniformly by appropriately regulating the dimensions of each portion.

  In each example shown in the figure, the friction roller type transmission is used as a speed reducer. However, if the input shaft and the output shaft are interchanged, they can be used as a speed increaser. The present invention can also be applied to a planetary roller type structure as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Vehicle drive electric motor 2, 2a, 2b, 2c Friction roller type reduction gear 3 Transmission 4 Rotation transmission device 5, 5a Input shaft 6 Output shaft 7 Drive side rotation shaft 8 Drive side rotation shaft 9a, 9b Gear transmission mechanism 10a 10b Clutch mechanism 11 Differential gears 12, 12a, 12b, 12c Sun rollers 13, 13a, 13b, 13c Annular roller 14 Planetary rollers 15, 15a Loading cam devices 16a, 16b, 16c, 16d, 16e Sun roller element 17 Planetary shaft 18 Carrier 19 Output shaft 20 Retaining ring 21 Support ring 22 Belleville spring 23 Cam plate 24 Ball 25 Driven side cam surface 26 Drive side cam surface 27 Intermediate roller 28 Rotating shaft 29 Housing 30 Connecting portion 31 Cylindrical surface 32 Partial conical convex surface 33, 33a Convex surface 34 Concave surface 35 Partial conical convex surface 36 Convex surface

Claims (3)

An input shaft and an output shaft, a sun roller, an annular roller, and a plurality of intermediate rollers;
Each of these intermediate rollers is installed in an annular space between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller so that it can rotate at least. Rolling contact with the surface and the inner peripheral surface of the annular roller,
The sun roller is composed of a pair of sun roller elements that are divided into two in the axial direction. These sun roller elements are pressed in the direction of approaching each other at least during power transmission and at the same speed in the same direction. Is rotating,
The input shaft and the output shaft can rotate relative to each other and rotate together with any one of the rollers or any roller while being concentrically arranged with the sun roller and the annular roller. In the friction roller type transmission in which the input shaft and the output shaft are coupled to different elements to two types of elements selected from among the supporting members
Regarding the cross-sectional shape of the peripheral surfaces of the rollers that are in rolling contact with each other with respect to a virtual plane including the central axis of the rollers, the cross-sectional shape of the outer peripheral surface of the sun roller element and the cross-sectional shape of the outer peripheral surface of the intermediate rollers The combination is a combination that lowers the surface pressure of the rolling contact portion between the peripheral surfaces of the respective rollers, rather than the combination of the cross-sectional shape of the outer peripheral surface of each of the intermediate rollers and the cross-sectional shape of the inner peripheral surface of the annular roller. Accordingly, the surface pressure of the rolling contact portion between the outer peripheral surface of the sun roller and the outer peripheral surface of each of the intermediate rollers is based on the difference in unevenness in the circumferential direction between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller. And a friction roller transmission characterized in that the difference between the surface pressure of the rolling contact portion between the outer peripheral surface of each intermediate roller and the inner peripheral surface of the annular roller is reduced or eliminated.   The cross-sectional shape of the outer peripheral surface of each intermediate roller is a partially arc-shaped convex arc, the cross-sectional shape of the outer peripheral surfaces of the two sun roller elements is a partially arc-shaped concave arc, and the cross-section of the inner peripheral surface of the annular roller The friction roller transmission according to claim 1, wherein the shape is a straight line parallel to the central axis.   The cross-sectional shape of the outer peripheral surface of each intermediate roller is a partially arcuate convex arc, and the cross-sectional shapes of the outer peripheral surfaces of the two sun roller elements are straight lines that are inclined in a direction approaching the central axis as they approach each other, The friction roller type transmission according to claim 1, wherein a cross-sectional shape of the inner peripheral surface of the roller is a convex arc having a partial arc shape.

Images