Speed reducer, vehicle, and electric vehicle

Abstract

To provide a frictional transmission type speed reducer which achieves high torque transmission efficiency, suppresses vibration and noise, and enables speed reduction at a high speed reduction ratio.SOLUTION: A speed reducer includes: a case; a sun roller which has a rotary shaft corresponding with a center axis and rotates around the axis of the rotary shaft relative to the case when rotation is input thereto; a plurality of intermediate rollers each of which has an outer peripheral surface pressed against the outer peripheral surface of the sun roller and rotates when receiving rotation of the sun roller; a moving mechanism which is provided at the case, supports the intermediate rollers, and moves the intermediate rollers relative to the sun roller in a radiation direction with respect to the center axis of the sun roller; a plurality of outer rollers each of which has an outer peripheral surface pressed against the outer peripheral surface of the intermediate roller and rotates when receiving rotation of the intermediate roller; and an outer ring which has an inner peripheral surface pressed against the outer peripheral surfaces of the outer rollers and rotates when receiving rotation of the outer rollers.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a speed reducer, a vehicle, and an electric vehicle.

Background Art

[0002] In recent years, as the motor for an electric vehicle (EV) has been evolving towards higher rotational speeds, the target rotational speed of the motor has come to be 50,000 revolutions per minute. In such a case, the speed reducer (drive system) combined with the motor is required to handle higher input rotational speeds, such as a higher reduction ratio than in the past.

[0003] As one way to handle such high input rotational speeds, a friction transmission type speed reducer is regarded as promising. In a friction transmission type speed reducer, since there is no gear engagement change, torque fluctuations and noise generation due to tooth impact are small. Also, since lubrication failure at the gear tooth root during high rotation does not occur, it is considered advantageous for high rotation.

[0004] For example, Patent Document 1 discloses a friction transmission type continuously variable transmission for a vehicle as described above.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] There is a need for a friction transmission type speed reducer that uses a high-speed motor, has high torque transmission efficiency, suppresses vibration and noise, and can achieve high reduction ratio reduction.

[0007] An object of the present invention is to provide a friction transmission type speed reducer that has high torque transmission efficiency, suppresses vibration and noise, and realizes high reduction ratio reduction.

Means for Solving the Problems

[0008] The speed reducer according to one aspect of the present invention includes a case, a sun roller having a rotation axis that coincides with a central axis and rotates around the axis of the rotation axis with respect to the case when rotation is input, and an outer peripheral surface that is pressed against the outer peripheral surface of the sun roller, and a plurality of intermediate rollers that rotate in response to the rotation of the sun roller, a moving mechanism that is provided in the case, supports each of the plurality of intermediate rollers, and moves the intermediate rollers with respect to the sun roller in a radial direction with respect to the central axis of the sun roller, and a plurality of outer rollers having an outer peripheral surface that is pressed against the outer peripheral surfaces of the plurality of intermediate rollers and rotates in response to the rotation of the intermediate rollers, and an outer ring having an inner peripheral surface that is pressed against the outer peripheral surface of the outer roller and rotates in response to the rotation of the outer roller.

Effects of the Invention

[0009] According to the present invention, (1) generating a high pressing load between friction surfaces during torque transmission in which rotational torque is transmitted from a motor, (2) making the pressing load proportional to the torque during torque transmission in which rotational torque is transmitted from a motor, (3) not generating a speed difference within the friction contact surface during torque transmission in which rotational torque is transmitted from a motor, (4) not having the case receive the pressing force of the friction surface during torque transmission in which rotational torque is transmitted from a motor are satisfied, and it is possible to provide a friction transmission type speed reducer that has high torque transmission efficiency, suppresses vibration and noise, and realizes high reduction ratio reduction.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0011] The electric vehicle 10 according to the embodiment will be described with reference to Figures 1 to 6.

[0012] Figure 1 shows a schematic diagram of a vehicle (a vehicle for an electric vehicle) 10a of the electric vehicle 10 according to the embodiment.

[0013] As shown in Figure 1, the vehicle 10a of the electric vehicle 10 includes a battery 12, an inverter 14, a motor 16, and a speed reducer (a speed reducer for an electric vehicle) 18. The battery 12 is used as a DC power source. The inverter 14 converts the DC power source from the battery 12 into an AC power source in order to drive the motor 16 driven by the AC power source. A speed reducer 18 that can be set to an appropriate reduction ratio is connected to the drive shaft of the motor 16. Then, the power reduced to a predetermined reduction ratio by the speed reducer 18 is transmitted to the wheels 22 via the drive shaft 20.

[0014] Note that the vehicle 10a may be rear-wheel drive, front-wheel drive, or all-wheel drive.

[0015] In the electric vehicle 10 shown in FIG. 1, the power decelerated by the speed reducer 18 is transmitted to the wheels 22 using the drive shaft 20. The vehicle 10a of the electric vehicle 10 may adopt a so-called in-wheel motor system in which, for example, the motor 16 and the speed reducer 18 are arranged on each wheel 22, and the wheels are directly driven from the speed reducer 18.

[0016] (First Embodiment) The speed reducer (roller type speed reducer) 18 according to the first embodiment will be described with reference to FIGS. 2 to 4.

[0017] FIG. 2 is a schematic front view of the speed reducer 18 according to the present embodiment. FIG. 3 is a schematic exploded perspective view of the speed reducer 18 according to the present embodiment.

[0018] As shown in FIGS. 2 and 3, the speed reducer 18 includes a case (base) 30, a sun roller 32, a plurality of intermediate rollers 34, a plurality of outer rollers 36, a plurality of outer roller connectors 38, an outer ring 40, a plurality of swing arm support pins (support pins) 42, and a swing arm 44 as a moving mechanism for moving the intermediate roller 34 in the radial direction with respect to the central axis of the sun roller 32.

[0019] The case 30 is formed as the exterior of the speed reducer 18. In FIGS. 2 and 3, only a part of the case 30 is shown. For simplicity of explanation, a part of the case 30 is formed, for example, in a flat plate shape. In the present embodiment, at least a part of the appearance of the case 30 is formed in a disk shape or a substantially disk shape. Note that the case 30 may be hollowed out, for example, for weight reduction.

[0020] The sun roller 32, the plurality of intermediate rollers 34, and the plurality of outer rollers 36 are preferably formed as substantially cylindrical rollers with their central axes (rotation axes) arranged parallel to each other to ensure the contact area and contact length with respect to each other.

[0021] The sun roller 32 receives rotation (driving force) from a motor 16 driven by electric power supplied from the battery 12. The sun roller 32 is rotatably supported about a predetermined rotation axis that coincides with the central axis with respect to the case 30 by a bearing (not shown). For this reason, when rotation is input, the sun roller 32 rotates about the axis of the rotation axis with respect to the case 30.

[0022] The case 30 is provided with a swing arm support pin 42 that rotatably supports the intermediate roller 34. The swing arm support pin 42 is fixed and integrated with the case 30, for example. The swing arm support pin 42 is formed in a cylindrical or columnar shape. The central axis of the swing arm support pin 42 is preferably arranged on a virtual axis parallel to the central axis of the sun roller 32 that penetrates the positions of the vertices of an equilateral triangle at a position equidistant from the central axis of the sun roller 32 in the case 30. Note that such an arrangement of the swing arm support pin 42 may be shifted from the positions of the vertices of the equilateral triangle in order to reduce noise generated from the speed reducer 18. In the present embodiment, three swing arm support pins 42 are provided on one surface of the flat plate portion of the case 30. The three swing arm support pins 42 are formed, for example, in a columnar shape with the same size and the same shape.

[0023] Note that, of the case 30, the rotation axis at the position where the central axis of the sun roller 32 is supported is the central axis of the speed reducer 18. In other words, the central axis of the sun roller 32 is the central axis of the speed reducer 18.

[0024] The number of swing arm support pins 42 is preferably four if the number of intermediate rollers 34 is four. If there are four or more swing arm support pins 42, the central axes of the swing arm support pins 42 are preferably arranged on a virtual axis parallel to the central axis of the sun roller 32 that penetrates the positions of the vertices of a regular polygon at a position equidistant from the central axis of the sun roller 32 (central axis of the speed reducer 18) in the case 30. Note that such an arrangement of the swing arm support pin 42 may be shifted from the positions of the vertices of the regular triangle in order to reduce noise generated from the speed reducer 18.

[0025] And, a swing arm support pin 42 rotatably supports a swing arm 44 about an axis with a bearing (not shown) with the central axis of the swing arm support pin 42 as the rotation axis.

[0026] The swing arm 44 is swingably provided on the case 30 and allows radial movement of the sun roller 32 and the outer roller 36 with respect to the central axis of the sun roller 32. The swing arm 44 includes a cylindrical portion 44a through which the swing arm support pin 42 is inserted, a plate 44b that supports the cylindrical portion 44a, and an intermediate roller support pin 44c that is supported by the plate 44b. The central axis of the cylindrical portion 44a and the central axis of the intermediate roller support pin 44c are arranged in parallel. And, in a state where the swing arm support pin 42 is inserted into the cylindrical portion 44a of the swing arm 44, the central axis of the swing arm support pin 42 and the central axis of the cylindrical portion 44a coincide, and the central axis of the intermediate roller support pin 44c is arranged in parallel with the central axis of the swing arm support pin 42 and the central axis of the cylindrical portion 44a.

[0027] And, an intermediate roller 34 is rotatably supported about its axis by a bearing (not shown) on the intermediate roller support pin 44c. At this time, the central axis of the intermediate roller 34 coincides with the central axis of the intermediate roller support pin 44c.

[0028] In addition, the three sets of intermediate rollers 34, swing arm support pins 42, and swing arms 44 according to this embodiment are arranged in a positional relationship where the swing arm support pin 42, the plate 44b of the swing arm 44, and the intermediate roller 34 are arranged clockwise with respect to the central axis of the sun roller 32. It is preferable that the direction in which the plate 44b of the swing arm 44 extends is a direction orthogonal to the radial direction with respect to the central axis of the sun roller 32. It is also preferable that the direction in which the plate 44b of the swing arm 44 extends is appropriately shifted with respect to the direction orthogonal to the radial direction with respect to the central axis of the sun roller 32.

[0029] The speed reducer 18 according to this embodiment has six outer rollers 36. In this embodiment, the plurality of outer rollers 36 are formed in three pairs. That is, the speed reducer 18 includes three outer roller portions 37, with two outer rollers 36 in one pair. The outer peripheral surfaces of the two outer rollers 36 of one outer roller portion 37 are each in contact with the outer peripheral surface of one intermediate roller 34.

[0030] For this reason, each outer roller portion 37 includes a first roller (outer roller) 36 that is pressed against the outer peripheral surface of the intermediate roller 34 and also pressed against the inner peripheral surface of the outer ring 40, and a second roller (outer roller) 36 that is spaced apart from the first roller 36 in the circumferential direction, pressed against the outer peripheral surface of the intermediate roller 34, and also pressed against the inner peripheral surface of the outer ring 40. The first roller 36 and the second roller 36 are of the same size and have the same configuration.

[0031] A pair of outer rollers 36 of each outer roller portion 37 are supported in a separated state while being adjacent to each other by an outer roller coupler 38.

[0032] The outer roller coupler 38 includes a plate 38a and a pair of support pins 38b provided on the plate 38a.

[0033] The plate 38a is arranged parallel to the flat plate portion of the case 30 and is supported in contact with or spaced apart from the flat plate portion of the case 30. The pair of support pins 38b are formed in a cylindrical or columnar shape and are provided spaced apart on one surface side of the plate 38a. The pair of support pins 38b are fixed and integrated, for example, on one surface of the plate 38a. A pair of outer rollers (first roller, second roller) 36 are rotatably supported around the central axis of the pair of support pins 38b by bearings (not shown) respectively. The outer peripheral surfaces of the pair of outer rollers 36 supported in this way are spaced apart from each other. Therefore, the outer roller coupler 38 can connect the rotation axes of the first roller 36 and the second roller 36 of each outer roller portion 37 and rotate the first roller 36 and the second roller 36 in the same direction.

[0034] The inner peripheral surface of the outer ring 40 is formed so as to contact the outer peripheral surfaces of all three pairs of outer rollers 36. The central axis of the outer ring 40 is arranged parallel to the central axes of the sun roller 32, the plurality of intermediate rollers 34, and the plurality of outer rollers 36. Also, the central axis of the outer ring 40 is arranged to coincide with the central axis of the sun roller 32. The inner peripheral surface of the outer ring 40 is preferably formed to have an appropriate height along the central axis in order to ensure the contact area and contact length with the outer roller 36.

[0035] As shown in Fig. 3, when assembling the speed reducer 18, the sun roller 32, the intermediate roller 34 supported by the swing arm 44, the outer roller portion 37 supported by the outer roller coupler 38, and the outer ring 40 are assembled to the case 30 in an appropriate order. When these components are formed with appropriate precision, the speed reducer 18 is simply formed in an appropriate fitting state by merely arranging the sun roller 32, the intermediate roller 34 supported by the swing arm 44, the outer roller portion 37 supported by the outer roller coupler 38, and the outer ring 40 with respect to the case 30. For this reason, in the speed reducer 18, the central axis of the sun roller 32 is located at the position of the central axis of the speed reducer 18, the intermediate roller 34 is on the outside of the sun roller 32 along the radial direction with respect to the central axis of the sun roller 32, the outer roller portion 37 is on the outside of the intermediate roller 34 along the radial direction with respect to the central axis of the sun roller 32, and the outer ring 40 is arranged on the outside of the outer roller portion 37 along the radial direction with respect to the central axis of the sun roller 32.

[0036] At this time, the intermediate roller 34 supported by the swing arm 44 that rotates about the central axis of the swing arm support pin 42 is arranged at an appropriate position while moving radially with respect to the central axis of the sun roller 32 between the sun roller 32 and the pair of outer rollers 36.

[0037] Also, at this time, between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34, between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the outer roller 36, and between the outer peripheral surface of the outer roller 36 and the inner peripheral surface of the outer ring 40, they are in linear contact parallel to the central axis of the sun roller 32, respectively. The central axes of the sun roller 32, the intermediate roller 34, the outer roller 36, and the outer ring 40 are parallel to each other. Also, the central axis (rotation axis) of the sun roller 32 and the central axis (rotation axis) of the outer ring 40 coincide.

[0038] When the speed reducer 18 is formed in this way, a pressing load can be generated linearly parallel to the central axis of the sun roller 32 between the inner peripheral surface of the outer ring 40 and the outer peripheral surface of the outer roller 36, between the outer peripheral surface of the outer roller 36 and the outer peripheral surface of the intermediate roller 34, and further between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the sun roller 32. Therefore, the space between the inner peripheral surface of the outer ring 40 and the outer peripheral surface of the outer roller 36, between the outer peripheral surface of the outer roller 36 and the outer peripheral surface of the intermediate roller 34, and further between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the sun roller 32 are respectively pressed.

[0039] When assembling the speed reducer 18, the outer ring 40 may be slightly thermally expanded and then shrink-fitted onto the outside of the outer roller 36. In this case, an initial applied pressure can be generated between the inner peripheral surface of the outer ring 40 and the outer peripheral surface of the outer roller 36. And a higher pressing load can be generated linearly parallel to the central axis of the sun roller 32 between the inner peripheral surface of the outer ring 40 and the outer peripheral surface of the outer roller 36, between the outer peripheral surface of the outer roller 36 and the outer peripheral surface of the intermediate roller 34, and further between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the sun roller 32.

[0040] The operation of the speed reducer 18 according to this embodiment will be described with reference to FIG. 4.

[0041] When rotational torque is input from the motor 16 to the shaft portion 32a of the sun roller 32 on the central axis of the sun roller 32, the speed reducer 18 rotates at that position with the central axis of the sun roller 32 coinciding with the central axis of the speed reducer 18. Then, torque is transmitted from the sun roller 32, and the intermediate roller 34 and the outer roller 36 rotate substantially at their positions, and the outer ring 40 rotates about the axis of the central axis of the sun roller 32. In this embodiment, the rotation direction of the sun roller 32 and the rotation direction of the outer ring 40 are the same direction.

[0042] When rotational torque is input from the motor 16 to the sun roller 32 during torque transmission, a force acts so as to enter between the outer peripheral surface that becomes the friction surface of the intermediate roller 34 according to the rotational direction, the outer peripheral surface that becomes the friction surface of the sun roller 32, and the outer peripheral surfaces that become the friction surfaces of the pair of outer rollers 36. At this time, a force continues to act in the normal direction of the linear contact surface parallel to the central axis of the sun roller 32 between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34. A force continues to act in the normal direction of the linear contact surface parallel to the central axis of the sun roller 32 between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surfaces of the pair of outer rollers 36. At this time, the intermediate roller 34 abuts on the sun roller 32 and the pair of outer rollers 36 at one linear location parallel to the central axis of the sun roller 32, respectively. For this reason, the intermediate roller 34 rotates while being linearly supported parallel to the central axis of the sun roller 32 at three locations spaced apart from each other with respect to the sun roller 32 and the pair of outer rollers 36. Then, the swing arm 44 rotates within a minute range with the central axis of the swing arm support pin 42 as the rotation axis so that the normal forces between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34 and between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surfaces of the pair of outer rollers 36 are balanced. For this reason, the movement of the intermediate roller 34 can be considered to be along the radial direction with respect to the central axis of the sun roller 32. For this reason, the intermediate roller 34 transmits torque from the sun roller 32 to the pair of outer rollers 36 via the intermediate roller 34 while appropriately moving in the radial direction with respect to the central axis of the sun roller 32. Further, a force continues to act in the normal direction of the linear contact surface parallel to the central axis of the sun roller 32 between the outer peripheral surfaces of the pair of outer rollers 36 and the inner peripheral surface that becomes the friction surface of the outer ring 40. These three normal directions are parallel to one plane (virtual plane) parallel to the flat plate portion of the case 30.

[0043] Therefore, when rotational torque is input from the motor 16 to the sun roller 32, the sun roller 32, the intermediate roller 34, and the outer roller 36 are balanced within the outer ring 40 in the speed reducer 18 according to this embodiment. Accordingly, when the speed reducer 18 is operating, it is possible to prevent a large load from being applied to the swing arm support pin 42 provided on the case 30 that supports the intermediate roller 34 via the swing arm 44. For this reason, the speed reducer 18 according to this embodiment prevents a large load from being applied to the case 30 of the speed reducer 18.

[0044] Further, according to this embodiment, when rotational torque is input from the motor 16 to the sun roller 32, the speed reducer 18 can generate a high pressing load on each friction surface between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34, between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the outer roller 36, and between the outer peripheral surface of the outer roller 36 and the inner peripheral surface of the outer ring 40.

[0045] When rotational torque is input from the motor 16 to the sun roller 32, the outer peripheral surface of the intermediate roller 34 rotates smoothly with respect to the outer peripheral surface of the sun roller 32. Also, the outer peripheral surface of the outer roller 36 rotates smoothly with respect to the outer peripheral surface of the intermediate roller 34. And the inner peripheral surface of the outer ring 40 rotates smoothly with respect to the outer peripheral surface of the outer roller 36. For this reason, in the speed reducer 18 according to the present embodiment, between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34, and between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surfaces of the pair of outer rollers 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36), and between the outer peripheral surfaces of the pair of outer rollers 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36) and the inner peripheral surface of the outer ring 40, pressing loads proportional to the torque can be generated respectively. Therefore, by using the speed reducer 18 according to the present embodiment, when rotational torque is input from the motor 16 to the sun roller 32, the pressing load between the sun roller 32 and the intermediate roller 34, the pressing load between the intermediate roller 34 and the outer roller 36, and the pressing load between the outer roller 36 and the outer ring 40 can be transmitted in order from the sun roller 32 to the outer ring 40 so as to be proportional to the torque respectively. Therefore, by using the speed reducer 18 according to the present embodiment, the pressing load can be transmitted in order from the sun roller 32 to the outer ring 40 so as to be proportional to the torque respectively during torque transmission from the motor 16.

[0046] Further, when rotation is input to the sun roller 32 during torque transmission from the motor 16, the moving speed (circumferential speed) of the outer peripheral surface of the sun roller 32 and the moving speed (circumferential speed) of the outer peripheral surface of the intermediate roller 34 are the same or substantially the same, and the moving speed (circumferential speed) of the outer peripheral surface of the intermediate roller 34 and the moving speed (circumferential speed) of the outer peripheral surface of the outer roller 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36) are the same or substantially the same, and the moving speed (circumferential speed) of the outer peripheral surface of the outer roller 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36) and the moving speed (circumferential speed) of the outer peripheral surface of the outer ring 40 are the same or substantially the same. Therefore, in the speed reducer 18 according to the present embodiment, no speed difference or almost no speed difference occurs in the circumferential speeds of the outer peripheral surface of the sun roller 32, the outer peripheral surface of the intermediate roller 34, the outer peripheral surface of the outer roller 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36), and the inner peripheral surface of the outer ring 40. Therefore, in the speed reducer 18 according to the present embodiment, since the circumferential speed of the outer peripheral surface of the sun roller 32 and the circumferential speed of the inner peripheral surface of the outer ring 40 are equal, the outer ring 40 is decelerated by a ratio of their diameters with respect to the sun roller 32.

[0047] These contents are the same not only when the sun roller 32 receives the driving force from the motor 16 and rotates in the direction shown in FIG. 4, but also when it rotates in the direction opposite to the direction shown in FIG. 4. In this case, the outer ring 40 rotates in the direction opposite to the direction shown in FIG. 4 due to the transmission of power.

[0048] Therefore, according to the present embodiment, (1) generating a high pressing load between each friction surface in the speed reducer 18 during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18; (2) making the pressing load proportional to the torque during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18; (3) not generating a speed difference within the friction contact surface during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18; (4) not having the pressing force of the friction surface received by the case 30 during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18; A speed reducer 18 that satisfies all of these is provided. According to this embodiment, for example, by using a high-speed motor 16, it is possible to provide a friction transmission type speed reducer 18 that has high torque transmission efficiency, little vibration and noise, and realizes high reduction ratio reduction.

[0049] (Second Embodiment) The speed reducer (roller type speed reducer) 18 according to the second embodiment will be described with reference to FIGS. 5 and 6. This embodiment is a modification of the first embodiment, and the same members as those described in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted as much as possible.

[0050] FIG. 5 is a schematic exploded perspective view of the speed reducer 18 according to this embodiment.

[0051] As shown in FIG. 5, in this embodiment, the speed reducer 18 does not include a swing arm support pin 42 provided on the case 30 and a swing arm 44 supported by the swing arm support pin 42.

[0052] The speed reducer 18 according to this embodiment includes a case (base) 30, a sun roller 32, a plurality of intermediate rollers 34, a plurality of outer rollers 36, a plurality of outer roller connectors 38, an outer ring 40, and a plurality of intermediate roller support portions 52.

[0053] In this embodiment, the case 30 is formed with a plurality of groove portions 31 that allow the intermediate roller support portions 52 that support the intermediate rollers 34 to move within a predetermined range in the radial direction with respect to the central axis of the sun roller 32.

[0054] FIG. 6 shows the positional relationship between the groove portion 31 of the case 30 and the slider 54 of the intermediate roller support portion 52 described later.

[0055] As shown in FIGS. 5 and 6, although it is an example, the plurality of groove portions 31 are formed by a pair of straight portions 31a whose outer edges are parallel to each other and a pair of semi-circular portions 31b, like the track of an athletic stadium. At the center of each of the pair of semi-circular portions 31b of the groove portion 31, a virtual line R extending in the radial direction with respect to the central axis of the sun roller 32 intersects. For this reason, the groove portion 31 extends in the radial direction with respect to the central axis of the sun roller 32.

[0056] Note that the groove portion 31 is preferably formed as a concave groove, but it may also be through. When the groove portion 31 is through, it is assumed that the movement of the slider 54 in the thickness direction of the case 30 is restricted. That is, here, it is assumed that the slider 54 moves parallel to the flat plate portion of the case 30, and the movement in the thickness direction of the case 30 is ignored.

[0057] The intermediate roller support portion 52 has a slider 54 and an intermediate roller support pin 56 provided on the slider 54.

[0058] The slider 54 is provided on the case 30 and is used as a movement mechanism for moving the intermediate roller 34 in the radial direction with respect to the central axis of the sun roller 32. Although it is an example, the slider 54 is formed in a shape and size that fits into the groove portion 31. The slider 54 has, for example, a pair of straight portions 54a whose outer edges are parallel to each other and a pair of semi-circular portions 54b, like the track of an athletic stadium.

[0059] The distance D1 between the pair of straight portions 31a of the groove portion 31 is the same as or slightly larger than the distance D2 between the pair of straight portions 54a of the slider 54. Also, the length L1 of the pair of straight portions 31a of the groove portion 31 is longer than the length L2 of the pair of straight portions 54a of the slider 54.

[0060] Also, the diameter of the pair of semi-circular portions 31b of the groove portion 31 is the same as or slightly larger than the diameter of the pair of semi-circular portions 54b of the slider 54.

[0061] Therefore, the slider 54 disposed within the groove portion 31 is movable within a predetermined range along the virtual line R which is the longitudinal direction of the groove portion 31 within the groove portion 31. At this time, the slider 54 allows movement in the radial direction with respect to the central axis of the sun roller 32, but restricts movement in the circumferential direction with respect to the central axis of the sun roller 32. That is, with respect to the groove portion 31, the slider 54 is formed to have a size that allows movement in the radial direction with respect to the central axis of the sun roller 32 but restricts movement in the circumferential direction with respect to the central axis of the sun roller 32.

[0062] An intermediate roller support pin 56 is provided on the slider 54. The intermediate roller support pin 56 is formed in a cylindrical or columnar shape.

[0063] And, an intermediate roller 34 is rotatably supported about its axis by a bearing (not shown) on the intermediate roller support pin 56. At this time, the central axis of the intermediate roller 34 coincides with the central axis of the intermediate roller support pin 56.

[0064] As shown in FIG. 5, at the time of assembly, the speed reducer 18 is assembled to the case 30 in an appropriate order with the sun roller 32, the intermediate roller 34 supported by the intermediate roller support portion 52, the outer roller portion 37 supported by the outer roller coupler 38, and the outer ring 40. When these components are formed with appropriate precision, simply by arranging the sun roller 32, the intermediate roller 34 supported by the intermediate roller support portion 52, the outer roller portion 37 supported by the outer roller coupler 38, and the outer ring 40 with respect to the case 30, the speed reducer 18 is formed in an appropriate fitting state. For this reason, in the speed reducer 18, the central axis of the sun roller 32 is at the position of the central axis of the speed reducer 18, the intermediate roller 34 is on the outer side of the sun roller 32 along the radial direction with respect to the central axis of the sun roller 32, the outer roller portion 37 is on the outer side of the intermediate roller 34 along the radial direction with respect to the central axis of the sun roller 32, and the outer ring 40 is arranged on the outer side of the outer roller portion 37 along the radial direction with respect to the central axis of the sun roller 32.

[0065] At this time, the slider 54 of the intermediate roller support portion 52 is arranged at an appropriate position while appropriately moving in the longitudinal direction of the groove portion 31 of the case 30 (the direction along the virtual line R). Accordingly, the intermediate roller 34 supported by the intermediate roller support portion 52 is arranged at an appropriate position while appropriately moving radially with respect to the central axis of the sun roller 32 between the sun roller 32 and the pair of outer rollers 36.

[0066] Also, at this time, between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34, between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the outer roller 36, and between the outer peripheral surface of the outer roller 36 and the inner peripheral surface of the outer ring 40, they are in linear contact parallel to the central axis of the sun roller 32, respectively. The central axis of the sun roller 32, the central axis of the intermediate roller 34, the central axis of the outer roller 36, and the central axis of the outer ring 40 are parallel to each other. Also, the central axis (rotation axis) of the sun roller 32 and the central axis (rotation axis) of the outer ring 40 coincide.

[0067] By forming the speed reducer 18 in this way, a pressing load can be generated linearly parallel to the central axis of the sun roller 32 between the inner peripheral surface of the outer ring 40 and the outer peripheral surface of the outer roller 36, between the outer peripheral surface of the outer roller 36 and the outer peripheral surface of the intermediate roller 34, and further between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the sun roller 32. For this reason, between the inner peripheral surface of the outer ring 40 and the outer peripheral surface of the outer roller 36, between the outer peripheral surface of the outer roller 36 and the outer peripheral surface of the intermediate roller 34, and further between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the sun roller 32, they are respectively pressed.

[0068] The operation of the speed reducer 18 according to this embodiment will be described.

[0069] The operation of the speed reducer 18 is basically the same as that shown in FIG. 4. When rotational torque is input from the motor 16 to the shaft portion 32a of the sun roller 32 on the central axis of the sun roller 32, the speed reducer 18 rotates at that position with the central axis of the sun roller 32 coinciding with the central axis of the speed reducer 18. Further, torque is transmitted from the sun roller 32 to the speed reducer 18, and the intermediate roller 34 and the outer roller 36 rotate substantially at their positions, and the outer ring 40 rotates about the axis of the central axis of the sun roller 32. In the present embodiment, the rotation direction of the sun roller 32 and the rotation direction of the outer ring 40 are the same direction.

[0070] When rotational torque is input from the motor 16 to the sun roller 32 during torque transmission, a force acts so as to enter between the outer peripheral surface that becomes the friction surface of the intermediate roller 34 according to the rotational direction, the outer peripheral surface that becomes the friction surface of the sun roller 32, and the outer peripheral surfaces that become the friction surfaces of the pair of outer rollers 36. At this time, a force continues to act in the normal direction of the linear contact surface parallel to the central axis of the sun roller 32 between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34. A force continues to act in the normal direction of the linear contact surface parallel to the central axis of the sun roller 32 between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surfaces of the pair of outer rollers 36. At this time, the outer peripheral surface of the intermediate roller 34 contacts the outer peripheral surface of the sun roller 32 and the outer peripheral surfaces of the pair of outer rollers 36 at one linear location parallel to the central axis of the sun roller 32, respectively. For this reason, the intermediate roller 34 rotates while being linearly supported in three locations spaced apart from each other in a direction parallel to the central axis of the sun roller 32 with respect to the sun roller 32 and the pair of outer rollers 36. Then, so that the forces in the normal direction between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34 and between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surfaces of the pair of outer rollers 36 are balanced, the slider 54 of the intermediate roller support portion 52 that supports the intermediate roller 34 with respect to the groove portion 31 of the case 30 moves in a minute range in the radial direction (the direction along the virtual line R) with respect to the central axis of the sun roller 32. For this reason, the intermediate roller 34 transmits torque from the sun roller 32 to the pair of outer rollers 36 via the intermediate roller 34 while appropriately moving in the radial direction with respect to the central axis of the sun roller 32. Further, a force continues to act in the normal direction of the linear contact surface parallel to the central axis of the sun roller 32 between the outer peripheral surfaces of the pair of outer rollers 36 and the inner peripheral surface of the outer ring 40. These three normal directions are parallel to one plane (virtual plane) parallel to the flat plate portion of the case 30.

[0071] Therefore, when rotational torque is input from the motor 16 to the sun roller 32, the sun roller 32, the intermediate roller 34, and the outer roller 36 are balanced within the outer ring 40 in the speed reducer 18 according to this embodiment. Accordingly, when the speed reducer 18 is operating, the intermediate roller support portion 52 that supports the intermediate roller prevents a large load from being applied to the groove portion 31 of the case 30. For this reason, the speed reducer 18 according to this embodiment prevents a large load from being applied to the case 30 of the speed reducer 18.

[0072] Further, according to this embodiment, when rotational torque is input from the motor 16 to the sun roller 32, the speed reducer 18 can generate a high pressing load on each friction surface between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34, between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surface of the outer roller 36, and between the outer peripheral surface of the outer roller 36 and the inner peripheral surface of the outer ring 40.

[0073] When rotational torque is input from the motor 16 to the sun roller 32, the outer peripheral surface of the intermediate roller 34 rotates without slipping relative to the outer peripheral surface of the sun roller 32. Also, the outer peripheral surface of the outer roller 36 rotates without slipping relative to the outer peripheral surface of the intermediate roller 34. And the inner peripheral surface of the outer ring 40 rotates without slipping relative to the outer peripheral surface of the outer roller 36. Therefore, in the speed reducer 18 according to the present embodiment, between the outer peripheral surface of the sun roller 32 and the outer peripheral surface of the intermediate roller 34, between the outer peripheral surface of the intermediate roller 34 and the outer peripheral surfaces of the pair of outer rollers 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36), and between the outer peripheral surfaces of the pair of outer rollers 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36) and the inner peripheral surface of the outer ring 40, pressing loads proportional to the torque can be generated respectively. Thus, by using the speed reducer 18 according to the present embodiment, when rotational torque is input from the motor 16 to the sun roller 32, the pressing load between the sun roller 32 and the intermediate roller 34, the pressing load between the intermediate roller 34 and the outer roller 36, and the pressing load between the outer roller 36 and the outer ring 40 can be transmitted in order from the sun roller 32 to the outer ring 40 so as to be proportional to the torque respectively. Therefore, by using the speed reducer 18 according to the present embodiment, the pressing load can be transmitted in order from the sun roller 32 to the outer ring 40 so as to be proportional to the torque respectively during torque transmission from the motor 16.

[0074] Also, when rotation is input to the sun roller 32 during torque transmission from the motor 16, the moving speed (peripheral speed) of the outer peripheral surface of the sun roller 32 and the moving speed (peripheral speed) of the outer peripheral surface of the intermediate roller 34 are the same or substantially the same, and the moving speed (peripheral speed) of the outer peripheral surface of the intermediate roller 34 and the moving speed (peripheral speed) of the outer peripheral surface of the outer roller 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36) are the same or substantially the same, and the moving speed (peripheral speed) of the outer peripheral surface of the outer roller 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36) and the moving speed (peripheral speed) of the outer peripheral surface of the outer ring 40 are the same or substantially the same. Therefore, in the speed reducer 18 according to the present embodiment, no speed difference or almost no speed difference occurs in the peripheral speeds of the outer peripheral surface of the sun roller 32, the outer peripheral surface of the intermediate roller 34, the outer peripheral surface of the outer roller 36 (the outer peripheral surface of the first roller 36 and the outer peripheral surface of the second roller 36), and the inner peripheral surface of the outer ring 40. Therefore, in the speed reducer 18 according to the present embodiment, since the peripheral speed of the outer peripheral surface of the sun roller 32 and the peripheral speed of the inner peripheral surface of the outer ring 40 are equal, the outer ring 40 is decelerated by the ratio of their diameters with respect to the sun roller 32.

[0075] These contents are the same not only when the sun roller 32 rotates in the direction shown in FIG. 4 when receiving the driving force from the motor 16, but also when it rotates in the direction opposite to the direction shown in FIG. 4. In this case, the outer ring 40 rotates in the direction opposite to the direction shown in FIG. 4 due to the transmission of power.

[0076] Therefore, according to the present embodiment, (1) generating a high pressing load between each friction surface in the speed reducer 18 during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18, (2) making the pressing load proportional to the torque during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18, (3) not generating a speed difference within the friction contact surface during torque transmission when rotational torque is transmitted from the motor 16 to the speed reducer 18, When rotational torque is transmitted from the motor 16 to the speed reducer 18, the pressing force of the friction surface is not received by the case 30. A speed reducer 18 that satisfies all of the above is provided. Thus, according to the present embodiment, for example, by using a high-speed motor 16, it is possible to provide a friction transmission type speed reducer 18 that has high torque transmission efficiency, little vibration and noise, and realizes high reduction ratio reduction.

[0077] Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof at the implementation stage. Also, the respective embodiments may be combined and implemented as appropriate, and in that case, the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, if the problem can be solved and the effect can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention.

Explanation of Reference Numerals

[0078] 10... Electric vehicle, 10a... Vehicle, 12... Battery, 14... Inverter, 16... Motor, 18... Speed reducer, 20... Drive shaft, 22... Wheel, 30... Case, 31... Groove portion, 31a... Straight portion, 31b... Semicircular portion, 32... Sun roller, 32a... Shaft portion, 34... Intermediate roller, 36... Outer roller, 37... Outer roller portion, 38... Outer roller connector, 38a... Plate, 38b... Support pin, 40... Outer ring, 42... Swing arm support pin, 44... Swing arm, 44a... Cylindrical portion, 44b... Plate, 44c... Intermediate roller support pin, 52... Intermediate roller support portion, 54... Slider, 54a... Straight portion, 54b... Semicircular portion, 56... Intermediate roller support pin.

Claims

1. A case, a sun roller having a rotation axis that coincides with a central axis and rotating about the axis of the rotation axis with respect to the case when rotation is input, a plurality of intermediate rollers having an outer peripheral surface pressed against the outer peripheral surface of the sun roller and rotating by receiving the rotation of the sun roller, a moving mechanism supported by the case, rotatably supporting each of the plurality of intermediate rollers, and moving the intermediate rollers in a radial direction with respect to the central axis of the sun roller with respect to the sun roller, a plurality of outer rollers having an outer peripheral surface pressed against the outer peripheral surfaces of the plurality of intermediate rollers and rotating by receiving the rotation of the intermediate rollers, an outer ring having an inner peripheral surface pressed against the outer peripheral surface of the outer roller and rotating by receiving the rotation of the outer roller and having a speed reducer.

2. The moving mechanism is swingably provided on the case and includes a swing arm that moves the intermediate roller in a radial direction with respect to the central axis of the sun roller with respect to the sun roller and the outer roller, The speed reducer according to claim 1.

3. The moving mechanism is provided movably in a radial direction with respect to the central axis of the sun roller with respect to the case and includes a slider that moves the intermediate roller in a radial direction with respect to the central axis of the sun roller with respect to the sun roller and the outer roller, The speed reducer according to claim 1.

4. Each of the plurality of outer rollers a first roller pressed against the outer peripheral surface of the intermediate roller and pressed against the inner peripheral surface of the outer ring, a second roller spaced in the circumferential direction from the first roller, pressed against the outer peripheral surface of the intermediate roller, and pressed against the inner peripheral surface of the outer ring, and includes The speed reducer has a coupler that connects the rotation axis of the first roller and the rotation axis of the second roller and rotates the first roller and the second roller in the same direction. The speed reducer according to any one of claims 1 to 3.

5. The speed reducer according to any one of claims 1 to 3, a motor that inputs a driving force to the sun roller of the speed reducer, a battery that supplies electric power for driving the motor and having a vehicle.

6. An electric vehicle including the vehicle according to claim 5.

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