JP5488492B2 - Continuously variable transmission - Google Patents

Description

  The present invention relates to a continuously variable transmission.

  As a conventional transmission of a so-called traction drive system, for example, Patent Document 1 discloses a transmission that tilts a traction planet and shifts by giving a skew angle to a planetary axis of a traction planet (planetary ball). ing. In this transmission, a pair of carriers respectively support both ends of the planetary shaft, a screw structure is provided between one carrier and the transmission main shaft, and a spline coupling portion is provided between the other carrier and the transmission main shaft. Provided. In the transmission, for example, the traction sun (sun roller) moves along the transmission main shaft, and one carrier is rotated with respect to the transmission main shaft, thereby causing a skew in the planetary shaft. The traction planet tilts and shifts.

Special table 2010-532454 gazette

  Incidentally, the transmission described in Patent Document 1 as described above has room for further improvement in terms of drive efficiency, for example.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a continuously variable transmission that can improve driving efficiency.

  In order to achieve the above-mentioned object, a continuously variable transmission according to the present invention is arranged such that a transmission shaft serving as a rotation center and the transmission shaft are opposed to each other in the axial direction, with a common first rotation center axis as the rotation center. A first rotation element and a second rotation element that are rotatable relative to each other; and a rotation center that is different from the first rotation center axis and that is rotatable about the first rotation element and the second rotation element. A rolling member that is sandwiched and capable of transmitting torque between the first rotating element and the second rotating element, a contact point between the first rotating element and the rolling member, the second rotating element, and the A transmission device that changes a rotation ratio between the respective rotating elements to be a gear ratio by changing a contact point with the rolling member by a tilting operation of the rolling member, the transmission shaft, and the first rotating element. And the first rotation relative to the second rotation element A third rotating element that is disposed on the transmission shaft so as to be relatively rotatable about a center axis as a rotation center, and whose outer surface is in contact with the rolling member and is not relatively movable in the axial direction of the transmission shaft; A support shaft that rotatably supports the rolling member with a rotation center axis as a rotation center, and a shaft that is disposed on the transmission shaft, and rotates the first rotation center axis with respect to the first rotation element and the second rotation element. A fourth rotating element that is relatively rotatable as a center and holds an end of the support shaft in a state in which the rolling member can be tilted; and a rotational torque generated in the fourth rotating element is transmitted to the transmission shaft. A torque axial force conversion mechanism that converts axial force along an axial direction and an axial force transmission mechanism that transmits the axial force to the third rotating element are provided.

  In the continuously variable transmission, the third rotating element may have an annular recess along the rotation direction on the outer surface.

  The continuously variable transmission according to the present invention has an effect that drive efficiency can be improved.

FIG. 1 is a schematic cross-sectional view of a continuously variable transmission according to an embodiment. FIG. 2 is a planetary ball seen in the direction of arrow X in FIG. 1 and is a diagram for explaining the input side frictional force and the output side frictional force during acceleration. FIG. 3 is a planetary ball as viewed from the direction of the arrow X in FIG. 1, and is a diagram for explaining the input side frictional force and the output side frictional force during deceleration. FIG. 4 is a diagram for explaining the rotational torque at the time of acceleration acting on the carrier. FIG. 5 is a diagram for explaining the rotational torque during deceleration acting on the carrier. FIG. 6 is a diagram showing the normal force of each contact portion at the time of acceleration in the planetary ball. FIG. 7 is a diagram illustrating an example of the normal force on the input side with respect to the gear ratio during acceleration. FIG. 8 is a diagram illustrating an example of the normal force on the output side with respect to the gear ratio during acceleration. FIG. 9 is a diagram illustrating the normal force of each contact portion during deceleration of the planetary ball. FIG. 10 is a diagram illustrating an example of the normal force on the input side with respect to the gear ratio during deceleration. FIG. 11 is a diagram illustrating an example of the normal force on the output side with respect to the gear ratio during deceleration. FIG. 12 is a diagram illustrating an example of the normal force on the input side with respect to the gear ratio. FIG. 13 is a diagram illustrating an example of the normal force on the output side with respect to the gear ratio. FIG. 14 is a diagram showing a bearing load acting on a bearing in each planetary ball.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

[Embodiment]
FIG. 1 is a schematic cross-sectional view of a continuously variable transmission according to an embodiment, and FIG. 2 is a planetary ball viewed in the direction of arrow X in FIG. 1 and explains input-side frictional force and output-side frictional force during acceleration. FIG. 3 is a planetary ball viewed from the direction of arrow X in FIG. 1 and is a diagram for explaining the input side friction force and the output side friction force at the time of deceleration. FIG. 4 is a diagram at the time of acceleration acting on the carrier. FIG. 5 is a diagram for explaining the rotational torque, FIG. 5 is a diagram for explaining the rotational torque acting on the carrier during deceleration, FIG. 6 is a diagram showing the normal force of each contact portion at the time of acceleration in the planetary ball, and FIG. FIG. 8 is a diagram illustrating an example of the normal force on the input side with respect to the gear ratio during acceleration, FIG. 8 is a diagram illustrating an example of the normal force on the output side with respect to the gear ratio during acceleration, and FIG. FIG. 10 is a diagram showing the normal force of each contact portion at the time of deceleration, and FIG. 10 is a method on the input side with respect to the gear ratio at the time of deceleration. FIG. 11 is a diagram illustrating an example of a force, FIG. 11 is a diagram illustrating an example of an output-side normal force with respect to a gear ratio during deceleration, FIG. 12 is a diagram illustrating an example of an input-side normal force with respect to a gear ratio, and FIG. These are figures which show an example of the normal force of the output side with respect to a gear ratio, and FIG. 14 is a figure which shows the bearing load which acts on the bearing in each planetary ball.

  The continuously variable transmission according to the present embodiment is mounted on a vehicle and transmits power (torque) generated by a power source such as an internal combustion engine to drive wheels of the vehicle. This continuously variable transmission is a so-called traction drive type continuously variable transmission that can transmit power between the rotating elements by a fluid such as traction oil (transmitted oil) interposed between the rotating elements in contact with each other. The continuously variable transmission uses the resistance force (traction force, shear force of the traction oil film) generated when shearing the traction oil intervening on the contact surface between one rotating element and the other rotating element to provide power (torque). To communicate.

  The continuously variable transmission according to the present embodiment is a so-called ball planetary continuously variable transmission (CVP), such as a female screw on the inner peripheral surface of the carrier, a male screw on the outer peripheral surface of the transmission shaft, and the like. And a mechanism capable of converting a rotational force generated in the carrier into an axial force, and a configuration in which the converted axial force is received by a sun roller. And this embodiment can reduce the excessive normal force on the output member side, for example, by converting the rotational force generated in the carrier into an axial force by these components and transmitting it to the sun roller. Driving efficiency can be improved.

  Specifically, as shown in FIG. 1, the continuously variable transmission mechanism that forms the main part of the continuously variable transmission 1 of the present embodiment has a common first rotation center axis R <b> 1 and is capable of relative rotation between them. A first rotating member 10 as a possible first rotating element, a second rotating member 20 as a second rotating element, a sun roller 30 as a third rotating element, a carrier 40 as a fourth rotating element, and a first rotation center axis A planetary ball 50 as a plurality of rolling members each having a second rotation center axis R2 different from R1, and a transmission shaft 60 serving as the rotation center of the first rotation member 10, the second rotation member 20, the sun roller 30, and the carrier 40. With. The continuously variable transmission 1 changes the gear ratio between input and output by inclining the second rotation center axis R2 with respect to the first rotation center axis R1 and tilting the planetary ball 50.

  In the following description, unless otherwise specified, a direction along the first rotation center axis R1 or the second rotation center axis R2 is referred to as an axial direction, and a direction around the first rotation center axis R1 is referred to as a circumferential direction. Further, a direction orthogonal to the first rotation center axis R1 is referred to as a radial direction, and among these, a side facing inward is referred to as a radial inner side, and a side facing outward is referred to as a radial outer side.

  In the continuously variable transmission 1, torque is typically transmitted between the first rotating member 10, the second rotating member 20, the sun roller 30, and the carrier 40 via each planetary ball 50. For example, in the continuously variable transmission 1, one of the first rotating member 10, the second rotating member 20, the sun roller 30, and the carrier 40 serves as a torque (power) input unit, and at least one of the remaining rotating elements is Torque output section. In the continuously variable transmission 1, the ratio of the rotation speed (the number of rotations) between any rotation element serving as an input unit and any rotation element serving as an output unit is a gear ratio.

  In the continuously variable transmission 1, a plurality of planetary balls 50 are arranged radially about the center axis (first rotation center axis R <b> 1) of the transmission shaft 60. The planetary ball 50 can rotate (spin) about the second rotation center axis R2 as the rotation center. The planetary ball 50 is sandwiched between the first rotating member 10 and the second rotating member 20 that are disposed on the transmission shaft 60 so as to face the transmission shaft 60 in the axial direction. In addition, when the carrier 40 rotates about the first rotation center axis R1, the planetary ball 50 rotates together with the carrier 40 and revolves around the first rotation center axis R1. The continuously variable transmission 1 presses at least one of the first rotating member 10 and the second rotating member 20 against the planetary ball 50, whereby the first rotating member 10, the second rotating member 20, the sun roller 30, the carrier 40, An appropriate frictional force (traction force) is generated between the planetary balls 50 and torque can be transmitted therebetween. The continuously variable transmission 1 tilts the planetary ball 50 on a tilt plane including the second rotation center axis R2 and the first rotation center axis R1, and the first rotation member 10 and the second rotation member 20 By changing the ratio of the rotational speed (rotational speed) between the input and output, the ratio of the rotational speed (rotational speed) between the input and output is changed.

  More specifically, the first rotating member 10 and the second rotating member 20 are a disk member (disk) or an annular member (ring) whose center axis coincides with the first rotation center axis R1, and is opposed in the axial direction. Thus, the planetary balls 50 are arranged so as to be sandwiched therebetween. In this example, both are circular members. The first rotating member 10 and the second rotating member 20 have contact surfaces that come into contact with the outer peripheral curved surface on the radially outer side of each planetary ball 50. The contact surfaces of the first rotating member 10 and the second rotating member 20 are, for example, a concave arc surface having a curvature equivalent to the curvature of the outer peripheral curved surface of the planetary ball 50, a concave arc surface having a curvature different from the curvature of the outer peripheral curved surface, or a convex It has a shape such as a circular arc surface or a flat surface. Here, the distance from the first rotation center axis R1 to the contact portion with each planetary ball 50 in a reference position state (the first rotation center axis R1 and the second rotation center axis R2 are parallel), which will be described later. The contact surfaces of the first rotating member 10 and the second rotating member 20 are formed so as to have the same length, and the contact angles θ of the first rotating member 10 and the second rotating member 20 with respect to the planetary balls 50 are the same. I try to be at an angle. Here, the contact angle θ is an angle from the reference to the contact portion with each planetary ball 50. Here, the radial direction is used as a reference. The contact surfaces of the first rotating member 10 and the second rotating member 20 with the planetary ball 50 are in point contact or surface contact with the outer peripheral curved surface of the planetary ball 50. Further, the contact surfaces of the first rotating member 10 and the second rotating member 20 with the planetary ball 50 have an axial force from the planetary ball 50 to the planetary ball 50 of the first rotating member 10 and the second rotating member 20. When applied, a force (normal force Fn) on the inner side in the radial direction and in the oblique direction (normal force Fn) is applied to the planetary ball 50.

  The continuously variable transmission 1 causes the first rotating member 10 to act as a torque input unit (input member) when the continuously variable transmission 1 is driven forward (when torque is input to a rotating element as an input unit). The second rotating member 20 acts as a torque output unit (output member) when the continuously variable transmission 1 is driven forward. In the continuously variable transmission 1, the input shaft 11 is connected to the first rotating member 10, and the output shaft 21 is connected to the second rotating member 20.

  The input shaft 11 includes a disk portion 11a and a cylindrical portion 11b having a central axis coinciding with the first rotation central axis R1. The 1st rotation member 10 is connected via the torque cam 12 mentioned later by the outer peripheral side of the disk part 11a. On the other hand, the continuously variable transmission 1 is provided with a cylindrical portion 11b on the inner peripheral side of the disk portion 11a. The inner peripheral surface of the cylindrical portion 11b is supported on the outer peripheral surface of the transmission shaft 60 via radial bearings RB1 and RB2 so as to be relatively rotatable. Therefore, the input shaft 11 can rotate relative to the transmission shaft 60.

  The output shaft 21 includes an annular portion 21a, a first cylindrical portion 21b, a disc portion 21c, and a second cylindrical portion 21d whose central axes are aligned with the first rotation central axis R1. The second rotating member 20 is fixed to the annular portion 21 a and rotates together with the output shaft 21. The annular portion 21a is extended on the outer peripheral side so that the first cylindrical portion 21b covers the first rotating member 10, the second rotating member 20, the input shaft 11, and the like. The second cylindrical portion 21 d is provided so as to cover the cylindrical portion 11 b of the input shaft 11. The disk portion 21c is disposed on the extended end of the first cylindrical portion 21b on the outer peripheral side, and is disposed on the end portion of the second cylindrical portion 21d on the inner peripheral side. The inner peripheral surface of the second cylindrical portion 21d is supported by the outer peripheral surface of the cylindrical portion 11b of the input shaft 11 so as to be relatively rotatable via radial bearings RB3 and RB4. Further, a thrust bearing TB1 is disposed between the outer peripheral plane of the disc portion 21c and the outer peripheral plane of the disc portion 11a in the input shaft 11. Therefore, the output shaft 21 can rotate relative to the input shaft 11.

  The main part of the continuously variable transmission 1 is housed in the case 71. The case 71 includes a cylindrical portion 71a, a disc portion 71b, and an annular portion 71c whose center axis is aligned with the first rotation center axis R1. One end of the cylindrical portion 71 a is closed, and the closed portion is fixed to the transmission shaft 60. The disk part 71b closes the opening of the cylindrical part 71a. The annular portion 71c extends from the inner peripheral surface of the cylindrical portion 71a toward the inside in the radial direction. The inner peripheral side of the disk portion 71b is supported on the outer peripheral surface of the second cylindrical portion 21d via a radial bearing RB5 so as to be relatively rotatable. A thrust bearing TB2 is disposed between the outer peripheral plane of the disk portion 71b and the outer peripheral plane of the disk portion 21c in the output shaft 21. Further, a thrust bearing TB3 is disposed between the plane of the annular portion 71c, the plane of the annular portion 21a in the output shaft 21, and the end surface of the first cylindrical portion 21b. Therefore, the output shaft 21 can perform relative rotation in the circumferential direction with respect to the case 71. Note that the transmission shaft 60 exemplified here is fixed to a fixed portion of the continuously variable transmission 1 in a case 71, a vehicle body (not shown), and the like, and is a cylindrical shape configured not to rotate relative to the fixed portion. A fixed shaft. The thrust bearing TB1 and the thrust bearing TB3 function as a reaction force receiver between the case 71 and the output shaft 21 when an axial force described later is generated.

  The sun roller 30 has a cylindrical shape with a center axis coinciding with the first rotation center axis R1, and is supported by bearings RB6 and RB7 so as to be able to rotate relative to the transmission shaft 60 in the circumferential direction. That is, the sun roller 30 is disposed on the transmission shaft 60 so as to be relatively rotatable with respect to the transmission shaft 60, the first rotating member 10, and the second rotating member 20 about the first rotation center axis R1. Further, the sun roller 30 is positioned with respect to the axial direction of the transmission shaft 60 by the outer ring of the bearing RB6, the outer ring of the bearing RB7, and the like, and is fixed so as not to move relative to the axial direction of the transmission shaft 60.

  Further, the outer surface 31 of the sun roller 30 is in contact with the plurality of planetary balls 50. On the outer peripheral surface 31 of the sun roller 30, a plurality of planetary balls 50 are radially arranged at substantially equal intervals. Therefore, the outer surface 31 of the sun roller 30 becomes a rolling surface when the planetary ball 50 rotates. The sun roller 30 can roll (rotate) each planetary ball 50 by its own rotation, or it can rotate along with the rolling (rotational) movement of each planetary ball 50. The sun roller 30 has an annular recess 32 on the outer peripheral surface 31 in the rotational direction, that is, in the circumferential direction. The recess 32 functions as a positioning mechanism for each planetary ball 50 with respect to the axial direction of the transmission shaft 60, whereby the sun roller 30 efficiently transmits the axial force to each planetary ball 50 when an axial force described later is generated. Is possible.

  The carrier 40 supports an end portion of a support shaft 51 described later so as not to hinder the tilting operation of each planetary ball 50. In the carrier 40, for example, a first disk part 41 and a second disk part 42 having a center axis coinciding with the first rotation center axis R1 are arranged to face each other, and the first disk part 41 and the second disk part 42 are disposed. Are connected by a plurality of connecting shafts (not shown) to form a bowl shape as a whole. As a result, the carrier 40 has an open portion on the outer peripheral surface. Each planetary ball 50 is disposed between the first disk portion 41 and the second disk portion 42, and a part protrudes radially outward from the outer peripheral surface of the carrier 40 through the open portion.

  The planetary ball 50 is a rolling member that rolls on the outer peripheral surface 31 of the sun roller 30. The planetary ball 50 is preferably a perfect sphere, but may have a spherical shape at least in the rolling direction, for example, a rugby ball having an elliptical cross section. The planetary ball 50 is rotatably supported by a support shaft 51 that passes through the center of the planetary ball 50. For example, the planetary ball 50 can be rotated relative to the support shaft 51 with the second rotation center axis R2 as the rotation axis (that is, rotation) by the radial bearings RB8 and RB9 disposed between the planetary ball 50 and the outer peripheral surface of the support shaft 51. I am doing so. Therefore, the planetary ball 50 can roll on the outer peripheral surface 31 of the sun roller 30 around the support shaft 51. Both ends of the support shaft 51 protrude from the planetary ball 50 and are held by the first disk portion 41 and the second disk portion 42 of the carrier 40 in a state in which each planetary ball 50 can be tilted.

  The reference position of the support shaft 51 is a position where the second rotation center axis R2 is parallel to the first rotation center axis R1 (position of the second rotation center axis R21 in FIG. 1). The support shaft 51 includes a reference position and a position inclined from the reference position in a tilt plane including the rotation center axis (second rotation center axis R2) and the first rotation center axis R1 formed at the reference position. Can be swung (tilted) together with the planetary ball 50. This tilt is performed with the center of the planetary ball 50 as a fulcrum in the tilt plane.

  In the continuously variable transmission 1, when the tilt angle of the planetary ball 50 is the reference position, that is, 0 degree, the first rotating member 10 and the second rotating member 20 rotate at the same rotational speed (same rotational speed). . That is, at this time, the rotation ratio (ratio of rotation speed or rotation speed) between the first rotation member 10 and the second rotation member 20 is 1, and the speed ratio γ is 1. On the other hand, when the planetary ball 50 is tilted from the reference position, the distance from the center axis of the support shaft 51 to the contact portion with the first rotating member 10 changes and the second axis from the center axis of the support shaft 51 changes. The distance to the contact portion with the rotating member 20 changes. Accordingly, either one of the first rotating member 10 and the second rotating member 20 rotates at a higher speed than when it is at the reference position, and the other rotates at a lower speed. For example, the second rotating member 20 has a lower rotation (deceleration) than the first rotating member 10 when the planetary ball 50 is tilted in one direction, and the first rotating member 10 is tilted in the other direction. (High speed). Therefore, in the continuously variable transmission 1, the rotation ratio (transmission ratio γ) between the first rotating member 10 and the second rotating member 20 can be changed steplessly by changing the tilt angle. it can. When the speed is increased (γ <1), the upper planetary ball 50 in FIG. 1 is tilted in the clockwise direction on the paper and the lower planetary ball 50 is tilted in the counterclockwise direction on the paper. . FIG. 1 illustrates the state at the time of this speed increase. Further, at the time of deceleration (γ> 1), the upper planetary ball 50 in FIG. 1 is tilted counterclockwise on the paper surface and the lower planetary ball 50 is tilted clockwise on the paper surface.

  The continuously variable transmission 1 is provided with a transmission 81 as a mechanism for changing the speed ratio γ. Since the gear ratio γ changes as the tilt angle φ of the planetary ball 50 changes, a tilting device that tilts each planetary ball 50 is used as the transmission 81. The transmission 81 changes the contact point between the first rotating member 10 and each planetary ball 50 and the contact point between the second rotating member 20 and each planetary ball 50 by changing the tilting operation of each planetary ball 50. The rotation ratio between the rotating elements to be the ratio is changed. As the speed change device 81, one known in this technical field is used. For example, the transmission 81 is composed of a support member having a radial direction in the longitudinal direction attached to one end portion of the extended support shaft 51 and an actuator that applies a radial force to the support member. Things can be considered. The transmission 81 tilts the planetary ball 50 via the support shaft 51 by moving the support member in the radial direction.

  Further, the continuously variable transmission 1 is provided with a guide portion for guiding the support shaft 51 in the tilting direction when the planetary balls 50 are tilted by the transmission 81. In this example, the guide part is provided on the carrier 40. The guide part is a radial guide groove 43 and a guide hole 44 for guiding the end part of the support shaft 51 protruding from the planetary ball 50 in the tilt direction, and the first disk part 41 and the second disk part 42 It forms for every planetary ball 50 in the part which opposes. That is, all the guide grooves 43 and all the guide holes 44 are radial when viewed from the axial direction. The guide groove 43 is provided along the radial direction of the first disk portion 41, and has a groove bottom 43a along the locus of the end surface of the support shaft 51 at the time of tilting. Here, a gap is provided between the end surface of the support shaft 51 and the groove bottom 43a in order to suppress friction loss during tilting. In the continuously variable transmission 1, since the transmission 81 is disposed between the second disk portion 42 and the case 71, the support shaft 51 needs to pass through the second disk portion 42. For this reason, the guide hole 44 is provided along the radial direction of the second disk portion 42, and penetrates the second disk portion 42 in the axial direction, and the support shaft 51 passes through the guide hole 44. It penetrates through the second disk part 42.

  In the continuously variable transmission 1, a frictional force (traction force) is generated between the first rotating member 10 and each planetary ball 50 as the first rotating member 10 rotates, and each planetary ball 50 starts rotating. The continuously variable transmission 1 generates a frictional force between each planetary ball 50 and the second rotating member 20 and between each planetary ball 50 and the sun roller 30 due to the rotation of each planetary ball 50. The two-rotating member 20 and the sun roller 30 also start to rotate. Similarly, in the continuously variable transmission 1, each planetary ball 50 starts rotating as the second rotating member 20 rotates, and the first rotating member 10 and the sun roller 30 also start rotating.

  The continuously variable transmission 1 can efficiently transmit rotational torque by optimizing the magnitude of the frictional force. Here, the frictional force capable of efficient torque transmission tends to be determined by the normal forces Fn1, Fn2, and Fn3 from the first rotating member 10, the second rotating member 20, and the sun roller 30 in each planetary ball 50. . In the continuously variable transmission 1, when the normal forces Fn1, Fn2, and Fn3 are excessive, the torque transmission efficiency may be deteriorated and the drive efficiency may be deteriorated. On the other hand, when torque is insufficient, torque transmission may be suppressed due to insufficient frictional force. In the continuously variable transmission 1, taking these into consideration, normal forces Fn1, Fn2, and Fn3 that generate an appropriate frictional force are determined as necessary normal forces Fnr1, Fnr2, and Fnr3. In the continuously variable transmission 1, the required normal force Fnr1 from the first rotating member 10 on the input side is constant regardless of the gear ratio γ (see, for example, FIG. 7). On the other hand, the required normal force Fnr2 from the second rotating member 20 on the output side is smaller than the required normal force Fnr1 as the value of the speed ratio γ decreases on the speed increasing side with the speed ratio γ = 1 as a boundary. As the speed ratio γ increases on the deceleration side, the required normal force Fnr1 tends to increase (see, for example, FIG. 8).

  The continuously variable transmission 1 is provided with an axial force generator that generates a force that is a source of the normal forces Fn1, Fn2, and Fn3, that is, an axial force (axial force). As the axial force generating device, a torque cam 12 that generates an axial force for pressing the first rotating member 10 against each planetary ball 50 is provided.

  The torque cam 12 is a torque axial force conversion mechanism that converts rotational torque into axial force Fa, and is disposed between the first rotating member 10 and a plane on the outer peripheral side of the disk portion 11 a in the input shaft 11. The torque cam 12 transmits the rotational torque of the input shaft 11 to the first rotating member 10 and generates an axial force Fa directed in the axial direction. The torque cam 12 transmits the rotational torque of the first rotating member 10 to the input shaft 11 and generates an axial force Fa directed in the axial direction. The thrust bearing TB1 is disposed at a position equivalent to the torque cam 12 in the radial direction across the input shaft 11, and is responsible for one of the axial forces Fa. Therefore, the other axial force Fa becomes a thrust in the axial direction and is applied to each planetary ball 50 via the first rotating member 10. Hereinafter, the other axial force Fa may also be referred to as thrust Fa. Further, the thrust Fa is transmitted to the second rotating member 20 and the output shaft 21 via each planetary ball 50. The thrust bearing TB3 is attached to the case 71 and is responsible for the thrust Fa. Therefore, a reaction force Fa similar to the thrust Fa is applied to each planetary ball 50 through the second rotating member 20.

  The normal forces Fn1 and Fn2 by the torque cam 12 are determined by the axial force Fa of the torque cam 12 and the contact angle θ, and become “Fa / sin θ”. On the input side (between the first rotating member 10 and each planetary ball 50), the axial force Fa, that is, the two torque cams 12 are adjusted so that the normal force Fn1 (= Fa / sin θ) becomes the required normal force Fnr1. If the specifications are set, it is possible to generate a frictional force capable of efficient torque transmission. However, with this setting according to the input side, on the output side (between the second rotating member 20 and each planetary ball 50), the normal force Fn2 (= Fa / sin θ) during deceleration is smaller than the required normal force Fnr2. There is a possibility that torque transmission cannot be performed due to insufficient frictional force. For this reason, with this axial force generator, the specifications of the torque cam 12 must be set according to the maximum value of the required normal force Fnr2, and an excessive normal force is generated at a gear ratio γ other than at the time of the most deceleration. Fn1 and Fn2 are generated, resulting in a decrease in torque transmission efficiency due to an excessive frictional force and a decrease in drive efficiency.

  Therefore, the continuously variable transmission 1 is provided with an axial force generator in addition to the torque cam 12. The other axial force generator generates an axial force Ff opposite to the thrust Fa generated by the torque cam 12 at the time of acceleration (γ <1), and the thrust Fa generated by the torque cam 12 at the time of deceleration (γ> 1). Is generated so that the axial force Ff is not generated at the reference position (γ = 1). Further, this axial force generator is configured to generate a larger axial force Ff as the speed ratio γ is smaller at the time of acceleration, and to generate a larger axial force Ff as the speed ratio γ is larger at the time of deceleration.

  Specifically, the continuously variable transmission 1 includes a torque axial force conversion mechanism 90 and an axial force transmission mechanism 91. The torque axial force conversion mechanism 90 converts the rotational torque generated in the carrier 40 into an axial force Ff along the axial direction of the transmission shaft 60. The axial force transmission mechanism 91 transmits the axial force Ff converted by the torque axial force conversion mechanism 90 to the sun roller 30.

  The torque axial force conversion mechanism 90 of the present embodiment includes a female screw portion 45 formed on the inner peripheral surface of the second disk portion 42 of the carrier 40 and an outer peripheral surface of the transmission shaft 60 screwed into the female screw portion 45. And a male screw portion 61. Here, the first disk portion 41 is assembled so as to be rotatable relative to the transmission shaft 60.

  Here, in the planetary ball 50, as the input torque increases, the frictional force (hereinafter referred to as “input-side frictional force”) at the contact portion with the first rotating member 10 (hereinafter referred to as “input-side contact portion”). Becomes larger. If the input torque is constant, the input side frictional force has the same magnitude even if the speed ratio γ changes. When the input torque is constant and the gear ratio γ is 1, the friction force (hereinafter referred to as “output-side contact portion”) between the input-side friction force on the planetary ball 50 and the second rotating member 20 (hereinafter referred to as “output-side contact portion”). Hereinafter, it is referred to as “output side frictional force”). On the other hand, in the planetary ball 50 at the time of acceleration (γ <1), as shown in FIG. 2, the output side friction force becomes smaller than the input side friction force, and the value of the speed ratio γ becomes smaller. The difference widens. On the other hand, in the planetary ball 50 at the time of deceleration (γ> 1), as shown in FIG. 3, the output-side frictional force becomes larger than the input-side frictional force, and the difference increases as the speed ratio γ increases. .

  A circumferential rotational torque corresponding to the difference between the input side frictional force and the output side frictional force is input to the carrier 40 for each planetary ball 50 via the support shaft 51. For example, the case where the 1st rotation member 10 rotates counterclockwise by input torque seeing from the input shaft 11 side to an axial direction is mentioned as an example. In this case, counterclockwise torque acts on the carrier 40 during acceleration (see FIG. 4), and clockwise torque acts during deceleration (see FIG. 5). Since the difference between the input side frictional force and the output side frictional force varies depending on the input torque and the gear ratio γ, the torque input to the carrier 40 at the time of acceleration or deceleration depends on the input torque and the gear ratio γ. Change. This torque increases as the speed ratio γ decreases as the speed increases, and increases as the speed ratio γ increases as the speed decreases.

  Since the torque axial force conversion mechanism 90 including the female screw portion 45 and the male screw portion 61 is provided between the carrier 40 and the transmission shaft 60, the carrier 40 is input from the planetary ball 50. The rotational torque can be moved in the axial direction together with the relative rotation with respect to the transmission shaft 60, and this action causes the rotational torque transmitted from each support shaft 51 to the carrier 40 to be axial force along the axial direction of the transmission shaft 60. It can be converted to Ff. In this new axial force generator, the greater the amount of movement in the axial direction (that is, the greater the input torque), the greater the axial force Ff is generated by the carrier 40. The direction of movement of the carrier 40 is matched with the direction of the axial force Ff. Therefore, the female screw portion 45 and the male screw portion 61 move the carrier 40 relative to the transmission shaft 60 in a direction opposite to the thrust Fa generated by the torque cam 12 at the time of acceleration, and to the same direction as the thrust Fa at the time of deceleration. Then, the thread shape is set so that the carrier 40 is moved relative to the transmission shaft 60. This axial force generator generates a larger axial force Ff as the speed ratio γ is smaller when the speed is increased, and as the speed ratio γ is larger when the speed is reduced.

  The amount of rotation of the carrier 40 and the amount of movement in the axial direction may be an amount that can transmit the axial force Ff to the sun roller 30 via an axial force transmission mechanism 91 described later. Therefore, it is preferable that the female screw portion 45 and the male screw portion 61 have a screw shape such as a screw pitch so that the axial force Ff can be generated with as little rotation amount of the carrier 40 as possible.

  The axial force transmission mechanism 91 uses, for example, the axial force Ff converted by the torque axial force conversion mechanism 90 via the annular protrusions 92 and 93 such as a snap ring fixedly provided on the transmission shaft 60. To communicate. The annular protrusions 92 and 93 are provided on both sides of the bearings RB6 and RB7 with respect to the axial direction of the transmission shaft 60. The annular projection 92 is provided between the first disk portion 41 and the inner ring of the bearing RB6 with respect to the axial direction at a position where the annular projection 92 can come into contact therewith. Between the two disk part 42 and the inner ring | wheel of bearing RB7, it provides in the position which can contact | abut these.

  In the continuously variable transmission 1 configured as described above, when the speed is increased, the carrier 40 is rotated with respect to the transmission shaft 60 by the action of the female screw portion 45 and the male screw portion 61 in the torque axial force conversion mechanism 90. As shown by a black arrow in FIG. 1, the rotational torque generated in the carrier 40 is opposite to the axial force Fa of the torque cam 12 as a result of relative movement in the axial direction opposite to the axial force Fa of the torque cam 12. Is converted into an axial force Ff. In the continuously variable transmission 1, the annular protrusion 93 of the axial force transmission mechanism 91 is pressed toward the bearing RB7 by the axial force Ff converted by the torque axial force conversion mechanism 90, whereby the axial force Ff is annular. This is transmitted to the sun roller 30 through the projection 93, the bearing RB7, etc., and an axial force Ff corresponding to the speed ratio γ acts on the sun roller 30. FIG. 6 shows the axial forces Fs1, Fs2 of the input side contact portion and the output side contact portion at that time, and normal forces Fn1, Fn1, generated at the input side contact portion and the output side contact portion by the axial forces Fs1, Fs2. Fn2 is shown.

  The axial force Fs1 at the time of acceleration at the input side contact portion is the axial force Fa itself by the torque cam 12 (Fs1 = Fa). On the other hand, the axial force Fs2 at the time of acceleration at the output side contact portion is obtained by subtracting the axial force Ff acting on the contact portion between the sun roller 30 and the planetary ball 50, that is, the sun roller contact portion, from the axial force Fa. (Fs2 = Fa-Ff). In this continuously variable transmission 1, the axial force difference Ff between the input and output appears on the thrust bearing TB1, but the thrust bearing TB2 takes charge of the reaction force corresponding to the axial force difference Ff.

  Since the contact angle is “θ”, as shown in FIG. 6, at the time of acceleration, the normal force Fn1 of the input side contact portion, the normal force Fn2 of the output side contact portion, and the sun roller contact portion at this time The normal force Fn3 is as follows.

Fn1 = Fa / sin θ
Fn2 = (Fa−Ff) / sin θ
Fn3 = (2Fa−Ff) / tan θ

  Here, since the axial force Fa is constant regardless of the gear ratio γ, the normal force Fn1 remains constant as “Fa / sin θ” (see FIG. 7). On the other hand, since the axial force Ff at the time of acceleration increases as the speed ratio γ decreases, the normal force Fn2 decreases by the amount of the axial force Ff as the speed ratio γ decreases. (See FIG. 8). 7 and 8 show examples of normal forces Fn1 and Fn2 at the time of acceleration.

  In the continuously variable transmission 1, during deceleration, the torque axial force conversion mechanism 90 rotates the carrier 40 in the direction opposite to that when the carrier 40 is accelerated with respect to the transmission shaft 60 due to the action of the female screw portion 45 and the male screw portion 61. As a result of relative movement in the axial direction in the same direction as the axial force Fa of the torque cam 12, the rotational torque generated in the carrier 40 has the same direction as the axial force Fa of the torque cam 12 as shown by the white arrow in FIG. It is converted into an axial force Ff. In the continuously variable transmission 1, the annular protrusion 92 of the axial force transmission mechanism 91 is pressed toward the bearing RB6 by the axial force Ff converted by the torque axial force conversion mechanism 90, whereby the axial force Ff is annular. This is transmitted to the sun roller 30 through the projection 92, the bearing RB6, etc., and an axial force Ff corresponding to the speed ratio γ acts on the sun roller 30. FIG. 9 shows the axial forces Fs1, Fs2 of the input side contact portion and the output side contact portion at that time, and normal forces Fn1, Fn1, generated at the input side contact portion and the output side contact portion by the axial forces Fs1, Fs2. Fn2 is shown.

  The axial force Fs1 at the time of deceleration at the input side contact portion is the axial force Fa itself by the torque cam 12 (Fs1 = Fa). On the other hand, the axial force Fs2 at the time of deceleration at the output side contact portion is obtained by adding the axial force Ff acting on the sun roller contact portion to the axial force Fa (Fs2 = Fa + Ff). In the continuously variable transmission 1, the thrust bearing TB3 takes charge of the reaction force corresponding to the axial force difference Ff between the input and output.

  At the time of deceleration, as shown in FIG. 9, the normal force Fn1 of the input side contact portion, the normal force Fn2 of the output side contact portion, and the normal force Fn3 at the sun roller contact portion at this time are as follows. .

Fn1 = Fa / sin θ
Fn2 = (Fa + Ff) / sin θ
Fn3 = (2Fa + Ff) / tan θ

  The normal force Fn1 remains “Fa / sin θ” as in the case of acceleration (see FIG. 10). On the other hand, since the axial force Ff increases as the speed ratio γ increases, the normal force Fn2 increases as the speed ratio γ increases (see FIG. 11). ).

  When the gear ratio γ is 1, there is no difference between the input side frictional force and the output side frictional force, so that no torque is input to the carrier 40 and the carrier 40 does not rotate relative to the transmission shaft 60. Therefore, the normal forces Fn1 and Fn2 at this time are “Fa / sin θ”.

  Therefore, the continuously variable transmission 1 optimizes the specifications of the torque cam 12 and applies the optimum axial force Fa by the torque cam 12, so that even one torque cam 12, for example, as shown in FIGS. 12 and 13, It can be suppressed that the normal force Fn1 generated at the input side contact portion and the normal force Fn2 generated at the output side contact portion are excessive with respect to the necessary normal forces Fnr1 and Fnr2. It is possible to suppress a decrease in torque transmission efficiency due to a strong frictional force and improve driving efficiency.

  That is, in the continuously variable transmission 1, for example, the cam angle of the torque cam 12 is set so that the axial force Fa matches the normal force Fn1 (= Fa / sin θ) of the input side contact portion with the required normal force Fnr1. Set the specifications. Thereby, as shown in FIG. 12, the continuously variable transmission 1 has the same normal force Fn1 as the required normal force Fnr1, and therefore has an optimum torque transmission efficiency at the input side contact portion. In the continuously variable transmission 1, in addition to setting the specifications of the torque cam 12, a torque axial force conversion mechanism 90 and an axial force transmission mechanism 91 are provided, and the female screw portion 45 and the male screw portion 61 are threaded. By appropriately setting the shape, as shown in FIG. 13, it is possible to suppress the normal force Fn2 generated at the output side contact portion from being excessive with respect to the required normal force Fnr2, and as a result, Also, a decrease in torque transmission efficiency can be suppressed even at the output side contact portion. As a result, the continuously variable transmission 1 can improve drive efficiency.

  In the continuously variable transmission 1, the torque axial force conversion mechanism 90 converts the rotational torque generated in the carrier 40 into the axial force Ff, and the axial force transmission mechanism 91 transmits the axial force Ff to the sun roller 30, for example. Compared with the case where the axial force Ff by the torque axial force conversion mechanism 90 is applied to the planetary ball 50 from the carrier 40, the load acting on the sun roller contact portion can be relatively reduced. For example, the normal force Fn3 when the axial force Ff is applied to the planetary ball 50 from the carrier 40 is as follows.

Fn3 (at the time of acceleration) = 2Fa / tan θ + Ff {(tan θ−tan φ) / tan θ tan φ}
Fn3 (during deceleration) = 2 Fa / tan θ + Ff {(tan θ + tan φ) / tan θ tan φ}

  As a result, since the continuously variable transmission 1 can relatively reduce the load acting on the sun roller contact portion, it is possible to improve the durability of the sun roller 30 and the planetary ball 50 and to further improve the torque transmission efficiency. It is possible to suppress the decrease and improve the driving efficiency.

  In the continuously variable transmission 1, since the sun roller 30 has an annular recess 32 along the rotation direction on the outer peripheral surface 31, each planetary ball 50 is positioned at an appropriate position with respect to the axial direction of the transmission shaft 60. As a result, the axial force Ff can be efficiently transmitted from the sun roller 30 to each planetary ball 50, so that the driving efficiency can be further improved.

  In the continuously variable transmission 1, the torque axial force conversion mechanism 90 converts the rotational torque generated in the carrier 40 into the axial force Ff, and the axial force transmission mechanism 91 transmits the axial force Ff to the sun roller 30, for example. The bearing load acting on the radial bearings RB8 and RB9 in each planetary ball 50 is relatively reduced as compared with the case where the axial force Ff by the torque axial force conversion mechanism 90 is applied to the planetary ball 50 from the carrier 40. can do. In the continuously variable transmission 1, for example, as shown in FIG. 14, the bearing loads F of the radial bearings RB8 and RB9 in each planetary ball 50 are as follows from the balance of moments acting on the planetary balls 50.

rball · Ff = 2rbrg · F
F = (rball / 2rbrg) · Ff

  Therefore, the bearing load F of the radial bearings RB8 and RB9 in each planetary ball 50 in the continuously variable transmission 1 can be expressed as follows.

    F = [1/2 (rbrg / rball)] · Ff

  On the other hand, the bearing load F of the radial bearings RB8 and RB9 in each planetary ball 50 when the axial force Ff is applied to the planetary ball 50 from the carrier 40 is, for example, as follows.

    F = (1 / 2sinφ) · Ff

  Therefore, the continuously variable transmission 1 has a small tilt angle φ (not very large geometrically), and usually the bearing is designed on the outside, so that 0 <sin φ << rbrg / rball <1 Thus, the bearing load acting on the radial bearings RB8 and RB9 in each planetary ball 50 can be relatively reduced. As a result, the continuously variable transmission 1 can relatively reduce the bearing load acting on the radial bearings RB8 and RB9 in each planetary ball 50, so that the durability of the radial bearings RB8 and RB9 and the planetary ball 50 is improved. In addition to being able to improve, further reduction in torque transmission efficiency can be suppressed and drive efficiency can be improved. Further, since the continuously variable transmission 1 can also reduce the shift load in the speed change operation by the transmission 81, the output and physique required for the power source of the transmission 81 can be suppressed. As a result, the device Can be miniaturized.

  According to the continuously variable transmission 1 according to the embodiment described above, the transmission shaft 60 serving as the rotation center and the transmission shaft 60 are disposed so as to face the transmission shaft 60 in the axial direction, and the common first rotation center axis R1 is the rotation center. The first rotation member 10 and the second rotation member 20 that can rotate relative to each other, and the second rotation center axis R2 that is different from the first rotation center axis R1 can rotate around the first rotation member 10 and the second rotation. A planetary ball 50 sandwiched between the member 20 and capable of transmitting torque between the first rotating member 10 and the second rotating member 20, a contact point between the first rotating member 10 and the planetary ball 50, and a second rotation. By changing the contact point between the member 20 and the planetary ball 50 by the tilting operation of the planetary ball 50, the transmission 81, the transmission shaft 60, the first Rotating member 10 The second rotation member 20 is disposed on the transmission shaft 60 so as to be relatively rotatable about the first rotation center axis R1 as a rotation center, and the outer peripheral surface 31 is in contact with the planetary ball 50 and is relative to the transmission shaft 60 in the axial direction. An unmovable sun roller 30, a support shaft 51 that rotatably supports the planetary ball 50 about the second rotation center axis R <b> 2, and a transmission shaft 60 are disposed on the first rotation member 10 and the second rotation member 20. With respect to the first rotation center axis R1 as a rotation center, the carrier 40 holding the end of the support shaft 51 in a state in which the planetary ball 50 can be tilted, and the rotational torque generated in the carrier 40 Is converted to an axial force along the axial direction of the transmission shaft 60, and an axial force transmission mechanism 91 that transmits this axial force to the sun roller 30 is provided. Therefore, the continuously variable transmission 1 transmits the axial force converted by the torque axial force conversion mechanism 90 to the sun roller 30 by the axial force transmission mechanism 91, for example, an excessive amount on the output member (second rotating member 20) side. The normal force can be reduced and the driving efficiency can be improved.

  The continuously variable transmission according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims.

  The torque axial force conversion mechanism may be provided between the first disk portion 41 of the carrier 40 and the transmission shaft 60, or between the first disk portion 41 and the transmission shaft 60, and the second disk portion 42. It may be provided both between the transmission shaft 60 and the transmission shaft 60. Further, the torque axial force conversion mechanism only needs to convert the rotational torque generated in the fourth rotation element into the axial force along the axial direction of the transmission shaft, and may be constituted by various cam mechanisms, for example.

1 continuously variable transmission 10 first rotating member (first rotating element)
12 Torque cam 20 Second rotating member (second rotating element)
30 Sun Roller (third rotating element)
31 Outer peripheral surface (outer surface)
32 Indentation 40 Carrier (fourth rotating element)
45 Female thread 50 Planetary ball (rolling member)
51 Support shaft 60 Transmission shaft 61 Male thread portion 71 Case 81 Transmission device 90 Torque axial force conversion mechanism 91 Axial force transmission mechanisms 92, 93 Annular protrusion R1 First rotation center axis R2 Second rotation center axis

Claims (2)

A transmission shaft as a center of rotation;
A first rotation element and a second rotation element that are arranged opposite to the transmission shaft in the axial direction and are capable of relative rotation about a common first rotation center axis;
It is rotatable about a second rotation center axis different from the first rotation center axis, and is sandwiched between the first rotation element and the second rotation element and between the first rotation element and the second rotation element. A rolling member capable of transmitting torque with,
By changing the contact point between the first rotating element and the rolling member and the contact point between the second rotating element and the rolling member according to the tilting operation of the rolling member, each rotation that becomes a gear ratio is achieved. A transmission that changes the rotation ratio between the elements;
The transmission shaft, the first rotation element, and the second rotation element are disposed on the transmission shaft so as to be relatively rotatable with the first rotation center axis as a rotation center, and an outer surface is in contact with the rolling member. A third rotating element that is not relatively movable in the axial direction of the transmission shaft;
A support shaft that rotatably supports the rolling member around the second rotation center axis;
It is disposed on the transmission shaft, is rotatable relative to the first rotation element and the second rotation element about the first rotation center axis, and the end of the support shaft is inclined to the rolling member. A fourth rotating element that is held in a state that allows rolling operation;
A torque axial force conversion mechanism that converts rotational torque generated in the fourth rotational element into axial force along the axial direction of the transmission shaft;
An axial force transmission mechanism for transmitting the axial force to the third rotating element;
Continuously variable transmission. The third rotation element has an annular recess along the rotation direction on the outer surface.
The continuously variable transmission according to claim 1.

Images