JP2012193793A - Friction roller type reduction gear and electric vehicle drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a structure having a loading cam device which is small in size, light in weight, easy in the securement of the efficiency of the face pressure of each traction part at starting, and also easy in the securement of sufficient durability.SOLUTION: Intermediate rollers 19, 19 are constituted of two pairs of intermediate roller elements 21, 21 constituting axial piece half parts of the intermediate rollers 19, 19, respectively. Elastic members such as disc springs 22, 22 are sandwiched between the two pairs of intermediate roller elements 21, 21 at each intermediate roller 19, 19. Then, elastic forces in directions in which axial dimensions are increased are imparted to the intermediate rollers 19, 19, and a preload for securing the face pressure of a rolling contact part between and among peripheral faces of a sun roller 4a, an annular roller 5a, and the intermediate rollers 19, 19 is imparted.

Description

  The present invention relates to an improvement of a friction roller type speed reducer that transmits torque from an electric motor to driving wheels in a state where the electric motor is incorporated in a driving system of an electric vehicle, for example.

  In order to improve the convenience of electric vehicles that have begun to spread in recent years, it is important to improve the efficiency of the electric motor in order to increase the travelable distance per charge. In order to improve this efficiency, it is effective to use a small electric motor that rotates at high speed, and to reduce the rotation of the output shaft of this electric motor before transmitting it to the drive wheels. Of the speed reducers used in this case, at least the first stage speed reducer directly connected to the output shaft of the electric motor has a very high operating speed, so friction and noise during operation can be reduced. It is conceivable to use a roller speed reducer. As a friction roller type speed reducer that can be used in such a case, for example, those described in Patent Documents 1 to 3 are known. Of these, the conventional structure described in Patent Document 3 will be described with reference to FIGS.

The friction roller speed reducer 1 includes an input shaft 2, an output shaft 3, a sun roller 4, an annular roller 5, a plurality of planetary rollers 6 and 6, each of which is an intermediate roller, a loading cam device 7, Is provided.
Among these, the sun roller 4 is concentric with each other with a pair of sun roller elements 8a and 8b divided in the axial direction around the input shaft 2 and with a gap interposed between the tip surfaces of each other. Of these, the sun roller element 8a is arranged so as to be rotatable relative to the input shaft 2. The outer peripheral surfaces of the two sun roller elements 8a and 8b are inclined surfaces that are inclined in a direction in which the outer diameter becomes smaller toward the respective front end surfaces, and these inclined surfaces serve as rolling contact surfaces. Therefore, the outer diameter of this rolling contact surface is small at the axially intermediate portion and becomes larger toward both ends.

The annular roller 5 has a circular shape as a whole, and is supported and fixed to a fixed portion such as a housing (not shown) in a state of being arranged concentrically with the sun roller 4 around the sun roller 4. . The inner peripheral surface of the annular roller 5 is a rolling contact surface inclined in a direction in which the inner diameter increases toward the axial center.
The planetary rollers 6 and 6 are disposed at a plurality of locations in the circumferential direction of the annular space 9 between the outer peripheral surface of the sun roller 4 and the inner peripheral surface of the annular roller 5. The planetary rollers 6, 6 are rotatable around planetary shafts 10, 10, which are rotation shafts, which are arranged in parallel with the input shaft 2 and the output shaft 3, respectively, via radial needle bearings. I support it. The base end portions of the planetary shafts 10 and 10 are supported and fixed to a carrier 11 coupled and fixed to the base end portion of the output shaft 3. The outer peripheral surfaces of the planetary rollers 6, 6 are convex curved surfaces having a partial arc shape on the generatrix, and are in rolling contact with the outer peripheral surface of the sun roller 4 and the inner peripheral surface of the annular roller 5, respectively.

  Further, the loading cam device 7 is provided between one sun roller element 8 a and the input shaft 2. For this purpose, a support ring 13 is locked to the intermediate portion of the input shaft 2 by a retaining ring 12, and the support ring 13 and the one sun roller element 8a are arranged in this order from the support ring 13 side. Further, a disc spring 14, a cam plate 15, and a plurality of balls 16, 16 each of which is a rolling element are provided. Then, the driven cam surfaces 17 and 17 and the driving cam surface 18 are respectively provided at a plurality of circumferential positions on the base end surface of the one sun roller element 8a and the one side surface of the cam plate 15 facing each other. , 18 are provided. Each of the cam surfaces 17 and 18 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 7, when the input shaft 2 is stopped, the balls 16, 16 are deepest on the cam surfaces 17, 18 as shown in FIG. Located in the part. In this state, the one sun roller element 8a is pressed toward the other sun roller element 8b by the elasticity of the disc spring 14. On the other hand, when the input shaft 2 rotates, the balls 16 and 16 move to shallow portions of the cam surfaces 17 and 18 as shown in FIG. Then, the distance between the one sun roller element 8a and the cam plate 15 is increased, and the one sun roller element 8a is pressed toward the other sun roller element 8b. As a result, the one sun roller element 8a is generated by the elasticity of the disc spring 14 and the balls 16, 16 riding on the cam surfaces 17, 18 toward the other sun roller element 8b. It is driven to rotate while being pressed by the larger one of the thrusts to be generated.

  During operation of the friction roller type speed reducer 1 as described above, the distance between the two sun roller elements 8a and 8b is reduced by the axial thrust generated by the loading cam device 7. And the surface pressure of the rolling contact portion between the outer peripheral surface of the sun roller 4 constituted by both the sun roller elements 8a and 8b and the outer peripheral surface of the planetary rollers 6 and 6 increases. As the surface pressure increases, the planetary rollers 6 and 6 are pushed outward in the radial direction of the sun roller 4 and the annular roller 5. Then, the surface pressure of the rolling contact portion between the inner peripheral surface of the annular roller 5 and the outer peripheral surfaces of the planetary rollers 6 and 6 also increases. As a result, the surface pressures of the plurality of rolling contact portions, which are provided between the input shaft 2 and the output shaft 3 and are to be used for power transmission, each of which is a traction portion, are determined by It rises according to the magnitude of the torque to be transmitted between.

  When the input shaft 2 is rotated in this state, the rotation is transmitted from the sun roller 4 to the planetary rollers 6, 6, and the planetary rollers 6, 6 are rotating around the sun roller 4. Revolve. The revolving motion of these planetary rollers 6 and 6 can be taken out by the output shaft 3 through the carrier 11. The surface pressure of each of the traction portions is appropriate according to the magnitude of torque to be transmitted between the two shafts 2 and 3, and excessive slip occurs in each of the traction portions, or these It is possible to prevent the rolling resistance from increasing due to excessive surface pressure of each traction section.

In the conventional friction roller type speed reducer 1 as described above, it is difficult to reduce the size and weight, increase the efficiency of securing the surface pressure of each traction portion at the time of startup, and ensure the durability.
First, the reason why it is difficult to reduce the size and weight is that the loading cam device 7 and the disc spring 14 for applying preload are both arranged in series around the input shaft 2 in the axial direction. Since the disc spring 14 and the retaining ring 12 and the support ring 13 for supporting the disc spring 14 are arranged in series with the loading cam device 7, the axial dimension is increased, and the surface is reduced in size and weight. Is disadvantageous.

  Further, it is disadvantageous from the viewpoint of improving the surface pressure securing efficiency because there are many movable parts existing between the disc spring 14 for applying the preload and the traction parts, and the efficiency is reduced due to friction loss. It is. In particular, the cam plate 15 is moved in the axial direction against the input shaft 2 against the frictional resistance of the spline engaging portion between the two members 15 and 2 by the elastic force of the disc spring 14. The loss due to the frictional resistance required for is increased. For this reason, the elasticity required for the disc spring 14 to increase the surface pressure required for each traction portion is increased, which is disadvantageous in terms of cost reduction, size reduction, and weight reduction.

  Furthermore, the reason why it is difficult to ensure the durability is that the disc spring 14 is easy to sag, and in the case of sag, excessive slip occurs in each traction portion when the friction roller type speed reducer 1 is started. . That is, as is widely known in the field of metal springs, if the disc spring 14 is repeatedly used in a state where it is completely crushed to a flat plate shape, it is difficult to ensure the durability of the disc spring 14. Specifically, the elasticity of the disc spring 14 is reduced (sagging) in a relatively short period of time, and the surface pressure of each of the traction portions is sufficiently ensured with a small torque applied to the input shaft 2. It becomes impossible, and it becomes easy to generate | occur | produce excessive slip in each of these traction parts.

JP 59-187154 A JP-A-61-136053 JP 2004-116670 A

  In view of the circumstances as described above, the present invention makes it easy to reduce the size and weight, and to ensure the efficiency of securing the surface pressure of each traction part at the time of start-up, and to ensure sufficient durability. The present invention has been invented to realize a friction roller type speed reducer provided with a cam device and a drive device for an electric vehicle incorporating the friction roller type speed reducer.

Of the friction roller type speed reducer and the electric vehicle drive device according to the present invention, the friction roller type speed reducer described in claim 1 is similar to the above-described conventionally known friction roller type speed reducer and the input shaft. And an output shaft, a sun roller, an annular roller, a plurality of intermediate rollers, and a loading cam device.
In particular, in the friction roller type speed reducer according to the present invention, each of the intermediate rollers is constituted by a pair of intermediate roller elements, each of which constitutes one half of the axial direction of each of the intermediate rollers. Further, an elastic member is sandwiched between a pair of intermediate roller elements for each of the intermediate rollers, and elasticity is applied to each of the intermediate rollers in a direction that increases the axial dimension. And the preload for ensuring the surface pressure of the traction part which is a rolling contact part of the surrounding surfaces of each said roller is provided.

According to a sixth aspect of the present invention, there is provided a drive device for an electric vehicle comprising: an electric motor; a friction roller type speed reducer having an input shaft that rotates together with an output shaft of the electric motor; and an input side transmission shaft and an output side transmission shaft. A transmission capable of converting the reduction ratio between the two to at least two stages of high and low, and a rotation transmission device for transmitting the rotation of the output side transmission shaft of the transmission to the drive wheels.
In particular, in the electric vehicle drive device of the present invention, the friction roller type speed reducer is the friction roller type speed reducer of the present invention as described above.

  According to the friction roller type speed reducer of the present invention configured as described above, it is easy to achieve a reduction in size and weight, and efficiency in securing the surface pressure of each of the traction portions at the time of start-up, and sufficient durability. Easy to secure. Therefore, it is possible to realize a friction roller type reduction gear that is small and has excellent transmission efficiency while ensuring the required durability. For example, when this friction roller type speed reducer is incorporated in a drive device for an electric vehicle, a highly efficient drive device can be realized and the travelable distance per charge can be increased.

Sectional drawing which shows the 1st example of embodiment of this invention. The enlarged view of the center upper part of FIG. The schematic diagram for demonstrating the behavior of each part accompanying the action | operation of a loading cam. The disassembled perspective view which shows the structure of the part which guides the autorotation shaft of an intermediate | middle roller to the radial direction of a sun roller and an annular roller. The figure similar to FIG. 2 which shows the 2nd example of embodiment of this invention. The schematic diagram which shows the 3rd example. Sectional drawing which shows the 4th example. The perspective view of the drive device for electric vehicles incorporating the friction roller type reduction gear. The diagram for demonstrating the acceleration characteristic obtained by this drive device. Sectional drawing which shows an example of a conventional structure. FIG. 11 is a cross-sectional view taken along the line aa in FIG. The schematic diagram equivalent to the bb cross section of FIG. 11 which each shows the state (B) which has generate | occur | produced similarly to the state (A) in which the loading cam apparatus is not generating the thrust.

[First example of embodiment]
1-4 show a first example of an embodiment of the present invention corresponding to claims 1 to 3. As shown in FIG. 1, the friction roller type speed reducer 1a of this example rotationally drives the sun roller 4a by the input shaft 2a, and the sun roller 4a is rotated through a plurality of intermediate rollers 19, 19. The rotation is transmitted to the roller 5a, and the rotation of the annular roller 5a is taken out from the output shaft 3a. Each of the intermediate rollers 19, 19 rotates only around the rotation shafts 20, 20 provided at the center thereof, and does not revolve around the sun roller 4 a. This sun roller 4a is formed by concentrically combining a pair of sun roller elements 8c, 8c having the same shape, and a pair of loading cams at a position sandwiching both the sun roller elements 8c, 8c from both sides in the axial direction. Devices 7a and 7a are installed. Further, each of the intermediate rollers 19, 19 is constituted by a pair of intermediate roller elements 21, 21, each of which constitutes one half of the axial direction of each of the intermediate rollers 19, 19. A pair of intermediate roller elements 21, 21 for each intermediate roller 19, 19 is sandwiched between disc springs 22, 22 that are elastic members, and the intermediate rollers 19, 19 are axially moved. Elasticity in the direction of increasing the dimensions is given. Each of these parts is housed in a stepped cylindrical housing 24 in which the diameter of the intermediate part in the axial direction is large and the diameters at both ends are small. Hereinafter, a specific configuration of each part will be described.

  First, the base half of the input shaft 2a (the right half of FIG. 1) is located inside the input side small diameter cylindrical portion 25 of the housing 24, and the multi-row ball bearing unit 26 causes the output shaft 3a to have the same output side small diameter. The cylindrical portion 27 is rotatably supported by a double row ball bearing unit 28. Further, a labyrinth seal 29 is provided between a pair of ball bearings constituting the double row ball bearing unit 28 so that foreign matter does not enter the housing 24 from the output shaft 3a disposed on the external space side. Like. The input shaft 2a and the output shaft 3a are arranged concentrically with each other, and the tip of the input shaft 2a is placed inside a circular recess 30 formed at the center of the base end surface of the output shaft 3a. It is supported by a bearing 31. With this configuration, the support rigidity (particularly radial rigidity) of the front half (left half of FIG. 1) of the input shaft 2a is ensured while ensuring the relative rotation between the input shaft 2a and the output shaft 3a. Secured.

  The two sun roller elements 8c, 8c are concentric with the input shaft 2a around the front half of the input shaft 2a, can be rotated relative to the input shaft 2a, and have their front end surfaces ( (Surfaces facing each other) are arranged with a gap between them. That is, in the case of this example, both the sun roller elements 8c and 8c are movable sun roller elements. The pair of cam plates 15a and 15a constituting the both loading cam devices 7a and 7a are positioned at two positions of the intermediate portion and the tip portion of the input shaft 2a, and the sun roller elements 8c and 8c are pivoted. It is fitted and fixed at positions sandwiched from both sides in the direction so as to rotate in synchronization with the input shaft 2a. Then, the driven cam surfaces 17 and 17 are driven at a plurality of positions in the circumferential direction between the base end surfaces of the sun roller elements 8c and 8c and the one side surfaces of the cam plates 15a and 15a, which face each other. Side cam surfaces 18 and 18 are provided. The shape of each of the cam surfaces 17 and 18 may be basically the same as that of the above-described conventional structure, but may be appropriately changed according to the required performance. In any case, each of the cam surfaces 17 and 18 has a depth in the axial direction that gradually changes in the circumferential direction, and is deepest at the center in the circumferential direction, and also becomes shallower toward both ends.

  Of the outer peripheral surfaces of the sun roller elements 8c, 8c, the portion that is in rolling contact with the outer peripheral surface of each of the intermediate rollers 19, 19 is a partial conical shape that is inclined in a direction in which the outer diameter decreases toward the tip surface. It is a convex surface, and outward flange-shaped flange portions 32, 32 are formed over the entire circumference on the outer peripheral surfaces of the base end portions of the sun roller elements 8c, 8c. The driven-side cam surfaces 17 and 17 are formed on the base end surfaces of the sun roller elements 8c and 8c including both the flange portions 32 and 32, respectively. The balls 16 and 16 are sandwiched between the driven cam surfaces 17 and 17 and the driving cam surfaces 18 and 18 formed on the cam plates 15a and 15a, respectively. The loading cam devices 7a and 7a are configured.

  On the other hand, each of the intermediate rollers 19, 19 has a pair of intermediate roller elements 21, 21 for each of the intermediate rollers 19, 19. The disc springs 22 and 22 are sandwiched between the intermediate roller elements 21 and 21. The inner peripheral surface of each of the intermediate roller elements 21 and 21 and the outer peripheral surface of each of the rotation shafts 20 and 20 are capable of axial displacement by non-circular engagement such as spline engagement, and synchronized rotation. Are freely combined. In addition, circular recesses 23 and 23 are provided on the entire circumference of the both sides of the intermediate roller elements 21 and 21 in the axial direction on the inner side, which is a side surface facing each other, excluding the outer diameter side end. Formed. Each of these circular recesses 23, 23 has a radial dimension and a depth dimension that can accommodate the respective disc springs 22, 22. In the case of this example, each of the disc springs 22 and 22 is formed by stacking a pair of base plates having different inclination directions, and the inner diameter of each of the circular recesses 23 and 23 is greater than the outer diameter of each of the base plates. Is a little bigger. Further, the depth dimension of each of these circular recesses 23, 23 is smaller than the axial dimension of each of these base plates in a free state, but larger than the thickness of each of these base plates.

  Further, the outer peripheral surface of each of the intermediate roller elements 21 and 21 is a cylindrical surface at a portion near the inner end in the axial direction, and a direction in which the outer diameter decreases from the intermediate portion or the portion near the outer end in the axial direction toward the outer end surface. It is a partial conical convex surface inclined in the direction of. The inclination angle of the partial conical convex surface is made to coincide with the inclination angle of the partial conical convex surface constituting the outer peripheral surface of the two sun roller elements 8c, 8c. Therefore, the outer peripheral surface of the sun roller 4a and the outer peripheral surfaces of the intermediate rollers 19 and 19 are in line contact with each other, and the contact area of each traction portion, which is a rolling contact portion between these peripheral surfaces, can be ensured. The intermediate rollers 19, 19 each having the above-described configuration are given elasticity in the direction of increasing the thickness dimension in the axial direction by the elasticity of the disk springs 22, 22. Based on the above, as will be described later, a preload for securing the surface pressure of each traction portion, which is a rolling contact portion between the circumferential surfaces of the rollers 4a, 5a, 19 is applied. Since the surface pressure of each of the traction portions can be efficiently secured based on the elasticity of each of the disc springs 22 and 22, the surface pressure can be sufficiently increased without increasing the elasticity of each of the disc springs 22 and 22. It can be secured. Further, since each of the disc springs 22 and 22 is housed in a portion between the intermediate roller elements 21 and 21, the structure for applying preload can be made compact, and the friction roller type speed reducer 1a can be made compact. It can be easily reduced in weight.

  The intermediate rollers 19 and 19 rotate (rotate) around the rotation shafts 20 and 20 in the annular space 9a between the inner circumferential surface of the annular roller 5a and the sun roller 4a. In addition to making it free, the annular roller 5a and the sun roller 4a are installed so as to be slightly displaced in the radial direction. For this purpose, a support frame 35 is supported and fixed to the inner surface of an end plate 34 that closes one axial direction side of the large-diameter cylindrical portion 33 of the housing 24. The support frame 35 includes the end plate 34, and has a structure like a carrier that constitutes a planetary gear mechanism. That is, the end plate 34 and the support plate 36 are disposed on both sides in the axial direction of the intermediate rollers 19, 19, and the both plates 34, 36 are arranged between the intermediate rollers 19, 19 in the circumferential direction. Coupled and fixed by stays installed in the space.

  Guide blocks 37 and 37 are supported and fixed to the opposing portions of the plates 34 and 36, respectively. Long guide long holes 38, 38 in the radial direction of the annular roller 5a and the sun roller 4a are formed on the inner side surfaces of the guide blocks 37, 37, respectively. On the other hand, single-row deep groove type ball bearings 39 and 39 are respectively fitted to the end portions of the respective rotation shafts 20 and 20, and the respective inner rings are externally fitted to the end portions of the respective rotation shafts 20 and 20. Is supported by. Further, the outer diameter of the outer ring constituting each of the ball bearings 39, 39 is slightly smaller (for example, several tens of μm to several tens of μm) than the width of each of the guide long holes 38, 38. Accordingly, each of the rotating shafts 20 and 20 is supported with respect to the support frame 35 so as to be able to be slightly displaced in the radial direction of the annular roller 5a and the sun roller 4a in a state where there is almost no rattling in the circumferential direction. Has been.

  Further, the annular roller 5a is disposed concentrically with the sun roller 4a in the peripheral portion of the sun roller 4a on the inner diameter side of the large-diameter cylindrical portion 33 provided at the axially intermediate portion of the housing 24. In the case of this example, the inner peripheral surface of the annular roller 5a is a cylindrical surface whose inner diameter does not change in the axial direction. Accordingly, the inner peripheral surface of the annular roller 5a and the outer peripheral surface of the intermediate portion of each of the intermediate rollers 19 and 19 are in line contact with each other, and the contact area of each traction portion which is a rolling contact portion between these peripheral surfaces can be ensured. . The annular roller 5a and the base end of the output shaft 3a are connected by a connecting portion 40 having an L-shaped cross section.

The friction roller type speed reducer 1a of the present example configured as described above operates as follows to transmit power from the input shaft 2a to the output shaft 3a while decelerating and at the same time increasing torque.
That is, when the input shaft 2a is rotationally driven by an electric motor, both the cam plates 15a and 15a fitted on the input shaft 2a are rotated. Then, the rotation of the sun roller 4a constituted by the both sun roller elements 8c and 8c is transmitted to the annular roller 5a through the intermediate rollers 19 and 19, and is taken out from the output shaft 3a. In order to circulate traction oil in the housing 24 during the operation of the friction roller type speed reducer 1a, the rolling contact portions (traction portions) between the peripheral surfaces of the rollers 4a, 19, 5a are A thin film of traction oil is present. Further, the intermediate rollers 19 and 19 are given elasticity in the direction of increasing the thickness dimension in the axial direction by the disc springs 22 and 22, respectively, and the intermediate rollers 19 and 19 are caused by this elasticity. The partial conical convex surface portion of the outer peripheral surface of the sun and the partial conical convex surface which is the outer peripheral surface of the sun roller 4a are engaged in a wedge shape. And based on this engagement, the surface pressure of the rolling contact portion between the outer peripheral surface of each of the intermediate rollers 19 and 19 and the outer peripheral surface of the sun roller 4a is increased, and at the same time, the intermediate rollers 19 and 19 are The annular roller 5a is displaced radially outwardly toward the inner peripheral surface of the annular roller 5a. As a result, the surface pressure of the rolling contact portion between the inner peripheral surface of the annular roller 5a and the outer peripheral surfaces of the intermediate rollers 19 and 19 also increases.

  Therefore, in the traction portion which is a rolling contact portion between the peripheral surfaces of these rollers 4a, 19, and 5a, torque can be transmitted without causing excessive slip immediately after the friction roller type speed reducer 1a is started. Further, after the friction roller type speed reducer 1a is activated, the balls 16 and 16 constituting the loading cam devices 7a and 7a move to the shallow side of the cam surfaces 17 and 18 (ride). The thickness dimension in the axial direction of both loading cam devices 7a, 7a increases. As a result, even when the surface pressure of each of the traction portions is further increased and the torque transmitted from the input shaft 2a to the output shaft 3a is increased, excessive slippage is not generated in each of the traction portions. This torque can be transmitted. The surface pressure of each of these traction sections is obtained by multiplying an appropriate value according to the torque to be transmitted between the input shaft 2a and the output shaft 3a, specifically, a necessary minimum value by an appropriate safety factor. Automatically adjusted to the value. As a result, regardless of fluctuations in the torque transmitted between the two shafts 2a and 3a, excessive slip occurs in each traction section, and conversely, the rolling resistance of each traction section increases. Therefore, the transmission efficiency of the friction roller type reduction gear 1a can be improved.

  When the friction roller type speed reducer 1a is started or the torque transmitted by the friction roller type speed reducer 1a varies, the sun roller 4a constituted by the both sun roller elements 8c and 8c. In addition, each of the intermediate rollers 19 and 19 may be slightly displaced in the axial direction. In the case of this example, the inner peripheral surface of the annular roller 5a, which is in rolling contact with the outer peripheral surfaces of these intermediate rollers 19, 19, is a simple cylindrical surface whose inner diameter does not change in the axial direction. Further, the guide long holes 38, 38 with which the ball bearings 39, 39 are engaged have a depth that allows the axial displacement. Therefore, the intermediate rollers 19 and 19 are smoothly displaced in the axial direction, and the rotation shafts 20 and 20 of the intermediate rollers 19 and 19 are not inclined.

  As described above, the intermediate rollers 19 and 19 are displaced radially outward of the annular roller 5a and the sun roller 4a in the process of securing or increasing the surface pressure of these traction portions. For example, as shown in FIG. 3A, the balls 16 and 16 are present at the bottoms of the cam surfaces 17 and 18, and the axial thicknesses of the loading cam devices 7a and 7a are the smallest. When the friction roller type speed reducer 1a is started from this state, as shown in FIG. 3B, the both loadings are performed based on the engagement between the balls 16, 16 and the cam surfaces 17, 18. The axial thickness of the cam devices 7a, 7a increases. In this process, the thickness dimension of each of the intermediate rollers 19, 19 is reduced. That is, after compressing the disc springs 22, 22, the intermediate rollers 19, 19 are displaced radially outward. In any case, the two sun roller elements 8c, 8c bite into the intermediate rollers 19 with respect to the radial direction of the friction roller type speed reducer 1a, and the intermediate rollers 19 are moved outward in the radial direction. Press to. In the case of this example, as shown in FIGS. 1, 2, and 4 described above, the outer rings of the ball bearings 39 and 39 that support both end portions of the intermediate rollers 19 and 19 are inserted into the guide long holes 38 and 38, respectively. Since they are in rolling contact with the side surfaces, the intermediate rollers 19 are smoothly displaced outward in the radial direction. And it prevents that the surface pressure of each said traction part becomes non-uniform | heterogenous. The structure of this example can improve the transmission efficiency of the friction roller type speed reducer 1a by making the surface pressure of each of these traction portions appropriate from this aspect as well.

In the case of this example, as described above, the intermediate roller elements 21 constituting the intermediate rollers 19 and 19 in the process of increasing the pressing force generated by the loading cam devices 7a and 7a. , 21 is reduced, and the disc springs 22 and 22 are crushed. However, since the disc springs 22 and 22 are disposed in the circular recesses 23 and 23, the intermediate roller elements 21 and 21 are formed before the disc springs 22 and 22 are completely crushed. The outer diameter side end portions of the inner side surfaces of the inner surfaces are in contact with each other. That is, even when the pressing force generated by the loading cam devices 7a and 7a is maximized, the disc springs 22 and 22 are not completely crushed. As a result, an unreasonable force is not applied to the disc springs 22 and 22 regardless of the operating state of the friction roller type speed reducer 1a. The elasticity of 22 and 22 does not decrease (sag), and the durability can be ensured.
Each of the circular recesses 23, 23 satisfies one of the requirements described in claim 3, and one intermediate roller element 21 of the pair of intermediate roller elements 21, 21 constituting each of the intermediate rollers 19, 19. , 21 may be formed only. However, according to the structure shown in the figure, the types of parts can be reduced.

[Second Example of Embodiment]
FIG. 5 shows a second example of an embodiment of the present invention corresponding to claims 1, 2, and 4. In the case of this example, a plurality of compression coil springs 40, 40 are provided for each of the intermediate rollers 19a as elastic members sandwiched between the intermediate roller elements 21a, 21a constituting each of the intermediate rollers 19a. For this purpose, a plurality of circumferentially equidistant intervals in the radially intermediate portion of the inner side surface, which is the side surface facing each other, of the pair of intermediate roller elements 21a and 21a in the axial direction of each intermediate roller 19a. Recessed holes 41 and 41 each having a circular cross section and having a bottom are formed in portions that are aligned with each other at locations (for example, about 6 to 10 locations). The inner diameter of each of the concave holes 41, 41 is slightly larger than the outer diameter of the compression coil springs 40, 40, and the depth is less than ½ of the total length of the compression coil springs 40, 40 in the free state. The compression coil springs 40, 40 are crushed and larger than ½ of the total length. Therefore, these compression coil springs 40, 40 can be inserted into the respective recessed holes 41, 41 at their respective end portions. Then, both end portions of the respective compression coil springs 40, 40 are inserted into the respective concave holes 41, 41, and both end surfaces of the respective compression coil springs 40, 40 are further connected to the rear end surfaces of the respective concave holes 41, 41. In the state of being abutted against each other, elasticity in a direction away from each other is applied between the intermediate roller elements 21a and 21a. The depths of the concave holes 41 and 41 are all the same, and the specifications including the axial lengths of the compression coil springs 40 and 40 are the same.

In the case of the structure of this example as described above, as in the first example of the above-described embodiment, it is easy to reduce the size and weight, and to improve the efficiency of securing the surface pressure of each traction part at the time of startup. Moreover, it is easy to ensure sufficient durability.
Since the elastic member for applying the preload is the same as the first example of the above-described embodiment except for the change from the disc spring 22 (see FIGS. 1 and 2) to the compression coil springs 40 and 40. The illustration and description regarding the equivalent parts are omitted.

[Third example of embodiment]
FIG. 6 shows a third example of the embodiment of the present invention. In the case of this example, the loading cam device 7a is provided only on one axial side of the sun roller 4b. For this reason, only one of the pair of solar roller elements 8c, 8d constituting the solar roller 4b (right side in FIG. 6) can be rotated relative to the input shaft 2b. The other (left side in FIG. 6) sun roller element 8d is supported and fixed to the input shaft 2b. In the case of this example, although it is disadvantageous in terms of securing the pressing force, the axial dimension can be shortened.
Since the configuration and operation of other parts are the same as those in the first example of the above-described embodiment or the second example of the above-described embodiment, overlapping illustration and description are omitted.

[Fourth Example of Embodiment]
FIG. 7 shows a fourth example of an embodiment of the present invention corresponding to claims 1 to 5. In the case of this example, the input shaft 2c of the friction roller type speed reducer 1b is used as the output shaft 43 itself of the electric motor 42. That is, the input shaft 2c and the output shaft 43 are configured concentrically and integrally with each other.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, redundant description is omitted.

[Fifth Example of Embodiment]
FIG. 8 shows a drive device for an electric vehicle incorporating a friction roller type speed reducer as a fifth example of the embodiment of the present invention corresponding to claim 6. This electric vehicle drive device includes an electric motor 42a, a friction roller type reduction gear 1c, a transmission 44, and a rotation transmission device 45. As for the friction roller type reduction gear 1c, for example, one having the same structure as that of the first example shown in FIG. 1 is used, and the input shaft 2a of the friction roller type reduction gear 1c and the electric motor 42a are connected. The output shaft 43a and the output shaft 43a are concentrically arranged so that torque can be transmitted. Further, the output shaft (not shown) of the friction roller type speed reducer 1c is arranged concentrically with the input side transmission shaft 46 of the transmission 44 and is connected so as to be able to transmit torque.

In this example, the transmission 44 is provided with a pair of gear transmission mechanisms 48a and 48b having different reduction ratios between the input side transmission shaft 46 and the output side transmission shaft 47. Then, by switching between the pair of clutch mechanisms 49a and 49b, only one of the gear transmission mechanisms 48a (48b) is allowed to transmit power so that the input side transmission shaft 46 and the output side transmission shaft 47 can be transmitted. The reduction ratio between and can be converted into two steps of high and low.
The rotation transmission device 45 is a general gear transmission mechanism in which a plurality of gears are combined. The rotation transmission device 45 transmits the rotation of the output-side transmission shaft 47 to the input portion of the differential gear 50, and a pair of left and right drive wheels. Is driven to rotate.

According to the structure of the driving apparatus for an electric vehicle of the present example as described above, the electric motor 42a is small and has a high rotation type (for example, the maximum rotation speed is about 30,000 min ⁻¹ for efficient use of electric energy. ) Can reduce vibration and noise during operation. That is, since the friction roller type speed reducer 1c is used as the first stage speed reducer, it is possible to suppress the occurrence of vibration at the high speed rotating portion. The rotational speeds of the transmission 44 and the rotation transmission device 45, each of which is a gear transmission mechanism, are approximately the same as the driving speed of a transmission portion of an automobile equipped with a general gasoline engine (up to several thousand min ⁻¹ Therefore, no unpleasant vibration or noise is generated in any part.

  Further, in the case of this example, by providing the speed change device 44, the relationship between the running speed and acceleration of the vehicle can be made smooth, similar to an automobile 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 the output shaft 43a of the electric motor 42a and the input portion of the differential gear 50, the acceleration (G) and traveling speed (km / h) of the electric vehicle 9), the left half of the solid line a in FIG. 9 and the chain line b are continuous. 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. 9 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 the transmission 44 is provided as in this example and the reduction ratio of the transmission 44 is changed according to the vehicle speed, the left half and the right half of the solid line a are made continuous. Can be obtained. This characteristic is almost the same as that of a gasoline engine vehicle having the same output shown by the broken line d in FIG. 9, and it can be seen that the same performance as that of a gasoline engine vehicle can be obtained in terms of acceleration performance and high speed performance.

  A feature of the present invention is a friction roller type speed reducer composed of a sun roller, a ring roller, and a plurality of intermediate rollers. Even when the input shaft is stopped, the rolling contact portions between the peripheral surfaces of these rollers are provided. It is in the structure to give the necessary pressurization. Although it is essential to rotate the sun roller with the input shaft, the roller rotating with the output shaft is not necessarily an annular roller. That is, the present invention can be implemented by a planetary roller type friction roller type reduction gear as shown in FIG. In this case, each intermediate roller is a planetary roller that revolves around the sun roller and revolves, and the base end of the output shaft is coupled to the carrier that supports each planetary roller.

  Furthermore, when implementing the invention relating to the electric vehicle drive device of the present invention, the type of the transmission device incorporated between the friction roller type reduction gear and the rotation transmission device is not limited. In addition to the illustrated structure, a planetary gear type transmission can also be employed. Furthermore, a belt-type or toroidal-type continuously variable transmission can be employed. If the continuously variable transmission is employed, the relationship between the traveling speed and acceleration of the vehicle as shown in FIG. 9 described above can be made smoother and closer to ideal.

1, 1a, 1b, 1c Friction roller type speed reducer 2, 2a, 2b, 2c Input shaft 3, 3a Output shaft 4, 4a, 4b Sun roller 5, 5a Annular roller 6 Planetary roller 7, 7a Loading cam device 8a, 8b 8c, 8d Sun roller element 9, 9a Annular space 10 Planetary shaft 11 Carrier 12 Retaining ring 13 Support ring 14 Belleville spring 15, 15a Cam plate 16 Ball 17 Drive side cam surface 18 Drive side cam surface 19, 19a Intermediate roller 20 Rotating shaft 21, 21a Intermediate roller element 22 Belleville spring 23 Circular recess 24 Housing 25 Input side small diameter cylindrical portion 26 Multi-row ball bearing unit 27 Output side small diameter cylindrical portion 28 Double row ball bearing unit 29 Labyrinth seal 30 Circular recess 31 Ball bearing 32鍔 33 Large cylindrical portion 34 End plate 35 Support frame 36 Support plate 37 Guide block 8 Guide long hole 39 Ball bearing 40 Compression coil spring 41 Recessed hole 42, 42a Electric motor 43, 43a Output shaft 44 Transmission device 45 Rotation transmission device 46 Input side transmission shaft 47 Output side transmission shaft 48a, 48b Gear transmission mechanism 49a, 49b Clutch mechanism 50 Differential gear

Claims (6)

An input shaft, an output shaft, a sun roller, an annular roller, a plurality of intermediate rollers, and a loading cam device;
Of these, the sun rollers are concentric to each other with a pair of sun roller elements divided in the axial direction around the input shaft, with a gap between the tip surfaces of the elements. The outer peripheral surfaces of the two sun roller elements are inclined surfaces that are inclined in a direction in which the outer diameter decreases toward the respective front end surfaces, and these two inclined surfaces are arranged. Rolling contact surface,
The annular roller is arranged concentrically with the sun roller around the sun roller, and has an inner peripheral surface as a rolling contact surface.
Each of the intermediate rollers is centered on a rotation shaft disposed in parallel with the input shaft at a plurality of locations in the circumferential direction of the annular space between the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller. In a state of being rotatably supported, each outer peripheral surface is in rolling contact with the outer peripheral surface of the sun roller and the inner peripheral surface of the annular roller,
The loading cam device is provided between a movable sun roller element, which is at least one of the sun roller elements, and the input shaft, and the movable sun roller is rotated along with the rotation of the input shaft. The element is rotated while being pressed in the axial direction toward the other sun roller element, and the driven cam surface provided at a plurality of circumferential directions on the base end face of the movable sun roller element, and the input Of the cam plate that is fixed to a part of the shaft and rotates together with the input shaft, between the drive side cam surfaces provided at a plurality of circumferential positions on one side facing the base end surface of the movable sun roller element. Each of the driving cam surfaces and the driven cam surfaces has a shape in which the depth in the axial direction gradually changes in the circumferential direction and becomes shallower toward the end portion. Are those having,
A friction roller that fixes one member of the annular roller and the member that supports the rotation shafts, and connects the other member to the output shaft so that the output shaft can be driven to rotate by the other member. In the type reducer,
Each of the intermediate rollers is constituted by a pair of intermediate roller elements, each of which constitutes one half of the axial direction of each of the intermediate rollers, and between each pair of intermediate roller elements for each of the intermediate rollers. An elastic member is sandwiched between the rollers, and elastic force in the direction of increasing the axial dimension is applied to each of the intermediate rollers, and a preload is applied to ensure the surface pressure of the rolling contact portion between the peripheral surfaces of the rollers. Friction roller speed reducer characterized by   Of the outer peripheral surfaces of the two sun roller elements, the portion that is in rolling contact with the outer peripheral surface of each intermediate roller is a partially conical convex inclined surface that is inclined in a direction in which the outer diameter decreases toward the tip surface. The outer peripheral surface of each of the intermediate rollers is present in the axially intermediate portion, the cylindrical convex surface having a constant outer diameter with respect to the axial direction, and the outer diameter is present in the axially opposite end portions toward the both axial end surfaces. A compound curved surface provided with a pair of inclined surfaces each of which is inclined in a decreasing direction and each having a partially conical convex shape, and the inner peripheral surface of the annular roller is a cylindrical concave surface whose inner diameter is constant in the axial direction The friction roller type reduction gear according to claim 1.   Each elastic member is a disc spring, and a portion excluding an outer diameter side end portion of inner side surfaces which are side surfaces facing each other among axial side surfaces of a pair of intermediate roller elements for each intermediate roller In addition, a recess having a radial dimension capable of accommodating the disc spring is formed over the entire circumference, and the total depth of the pair of recesses formed on the inner surface of the pair of intermediate roller elements is: The friction roller type speed reducer according to any one of claims 1 to 2, wherein the friction roller type speed reducer is larger than a thickness in a state where the disc spring is crushed in an axial direction.   Each of the elastic members is a plurality of compression coil springs, and each of the intermediate rollers has a pair of intermediate roller elements. Concave holes having an inner diameter that can accommodate the compression coil springs are formed at portions that are aligned with each other at a plurality of locations in the circumferential direction. The sum of the depths of the concave holes paired with each other is greater than the length in a state where the compression coil spring is crushed in the axial direction. Friction roller speed reducer.   The friction roller type reduction gear according to any one of claims 1 to 4, wherein the input shaft is the output shaft of the electric motor.   An electric motor, a friction roller reduction gear having an input shaft that rotates together with the output shaft of the electric motor, and an input transmission shaft and an output transmission shaft that are rotationally driven by the output shaft of the friction roller reduction gear. In order to transmit the speed reduction ratio between the input side transmission shaft and the output side transmission shaft to at least two levels of high and low, and the rotation of the output side transmission shaft of the transmission to the drive wheels In the drive device for electric vehicles provided with the rotation transmission device, the friction roller type speed reducer is the friction roller type speed reducer according to any one of claims 1 to 5. A driving device for an electric vehicle.

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