JP2017003046A - Toroidal type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toroidal type continuously variable transmission generating pressing force enough to start on a low-speed side without providing a strong preload member such as a disc spring, even in a low-temperature environment, preventing excessive pressing force on a high-speed side, and having high efficiency.SOLUTION: For a toroidal type continuously variable transmission, a tilting center Oof a power roller 11 is offset in a direction parallel with an input shaft 1 and in a direction of approaching an output side disc 3A, to a curvature center Oof discs 2, 3A.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a toroidal continuously variable transmission that can be used in transmissions of various industrial machines such as automobiles and pumps.

For example, a double-cavity toroidal continuously variable transmission used as a transmission for an automobile is configured as shown in FIGS. As shown in FIG. 7, the input shaft 1 is rotatably supported inside the casing 50, and two input side disks 2, 2 and two output side disks 3 are disposed on the outer periphery of the input shaft 1. 3 is attached. An output gear (transmission gear) 4 is rotatably supported on the outer periphery of the intermediate portion of the input shaft 1. Output side disks 3 and 3 are connected to cylindrical flange portions 4a and 4a provided at the center of the output gear 4 by spline coupling.
The input shaft 1 is rotationally driven by a drive shaft 22 via a loading cam type pressing device 12 provided between an input side disk 2 and a cam plate (loading cam) 7 located on the left side in FIG. It is like that. The output gear 4 is supported in the casing 50 via a partition wall 13 formed by coupling two members, so that the output gear 4 can rotate around the axis O of the input shaft 1 while the axis O. Directional displacement is prevented.

  The output side disks 3 and 3 are supported by needle bearings 5 and 5 interposed between the input shaft 1 and rotatable about the axis O of the input shaft 1. Further, the input disc 2 on the left side in FIG. 7 is supported on the input shaft 1 via a ball spline 6, and the input disc 2 on the right side in FIG. 7 is splined to the input shaft 1. The disk 2 rotates with the input shaft 1. A power roller is provided between the inner side surfaces (concave surface; also referred to as a traction surface) 2a and 2a of the input side disks 2 and 2 and the inner side surfaces (concave surface; also referred to as a traction surface) 3a and 3a of the output disks 3 and 3. 11 (see FIG. 8) is rotatably held.

  A step 2b is provided on the inner peripheral surface 2c of the input side disk 2 located on the right side in FIG. 7, and the step 1b provided on the outer peripheral surface 1a of the input shaft 1 is abutted against the step 2b. At the same time, the back surface (right surface in FIG. 7) of the input side disk 2 is abutted against a loading nut 9 screwed into a screw portion formed on the outer peripheral surface of the input shaft 1. Thereby, the displacement of the input side disk 2 in the direction of the axis O with respect to the input shaft 1 is substantially prevented. Further, a disc spring 8 is provided between the cam plate 7 and the flange 1d of the input shaft 1, and this disc spring 8 is a concave surface 2a, 2a, 3a of each disk 2, 2, 3, 3. , 3a and a pressing portion (preload) is applied to a contact portion between the peripheral surfaces 11a and 11a of the power rollers 11 and 11.

  8 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 8, a pair of trunnions 15, 15 that swing about a pair of pivots 14, 14 that are twisted with respect to the input shaft 1 are provided inside the casing 50. In addition, illustration of the input shaft 1 is abbreviate | omitted in FIG. Each trunnion 15, 15 is a pair of bent wall portions 20, 20 formed at both ends in the longitudinal direction (vertical direction in FIG. 8) of the support plate portion 16 so as to be bent toward the inner surface side of the support plate portion 16. have. The bent wall portions 20 and 20 form concave pocket portions P for accommodating the power rollers 11 in the trunnions 15 and 15. Further, the pivot shafts 14 and 14 are concentrically provided on the outer side surfaces of the bent wall portions 20 and 20, respectively.

  A circular hole 21 is formed in the central portion of the support plate portion 16, and the base end portion 23 a of the displacement shaft 23 is supported in the circular hole 21. Then, by swinging each trunnion 15, 15 about each pivot 14, 14, the inclination angle of the displacement shaft 23 supported at the center of each trunnion 15, 15 can be adjusted. Each power roller 11 is rotatably supported around the distal end portion 23b of the displacement shaft 23 protruding from the inner surface of each trunnion 15, 15, and each power roller 11, 11 is connected to each input side disk. 2 and 2 and between the output side disks 3 and 3. In addition, the base end part 23a and the front-end | tip part 23b of each displacement shaft 23 and 23 are mutually eccentric.

  Further, the pivot shafts 14 and 14 of the trunnions 15 and 15 are supported so as to be swingable with respect to the pair of yokes 23A and 23B and to be displaceable in the axial direction (vertical direction in FIG. 8). The horizontal movement of the trunnions 15 and 15 is restricted by 23B. Each yoke 23A, 23B is formed in a rectangular shape by pressing or forging a metal such as steel. Four circular support holes 18 are provided at the four corners of each of the yokes 23 </ b> A and 23 </ b> B, and the pivot shafts 14 provided at both ends of the trunnion 15 swing through the radial needle bearings 30. It is supported freely. Further, a circular locking hole 19 is provided in the central portion of the yokes 23A and 23B in the width direction (the left-right direction in FIG. 8), and the inner peripheral surface of the locking hole 19 is a cylindrical surface. 64 and 68 are fitted inside. That is, the upper yoke 23A is swingably supported by the spherical post 64 supported by the casing 50 via the fixing member 52, and the lower yoke 23B is supported by the spherical post 68 and the drive for supporting the same. The upper cylinder body 61 of the cylinder 31 is swingably supported.

  The displacement shafts 23 and 23 provided in the trunnions 15 and 15 are provided at positions 180 degrees opposite to the input shaft 1. Further, the direction in which the distal end portion 23b of each of the displacement shafts 23, 23 is eccentric with respect to the base end portion 23a is the same direction as the rotational direction of the both disks 2, 2, 3, 3 (up and down in FIG. 8). (Reverse direction). Further, the eccentric direction is a direction substantially orthogonal to the direction in which the input shaft 1 is disposed. Accordingly, the power rollers 11 and 11 are supported so that they can be slightly displaced in the longitudinal direction of the input shaft 1. As a result, even if each power roller 11, 11 tends to be displaced in the axial direction of the input shaft 1 due to elastic deformation of each component member based on the thrust load generated by the pressing device 12, each component This displacement is absorbed without applying an excessive force to the member.

  Further, between the outer surface of the power roller 11 and the inner surface of the support plate portion 16 of the trunnion 15, a thrust ball bearing (thrust bearing) 24 that is a thrust rolling bearing is sequentially formed from the outer surface side of the power roller 11. A thrust needle bearing 25 is provided. Among these, the thrust ball bearing 24 supports the rotation of each power roller 11 while supporting the load in the thrust direction applied to each power roller 11. Each of such thrust ball bearings 24 includes a plurality of balls (hereinafter referred to as rolling elements) 26, 26, an annular retainer 27 that holds the rolling elements 26, 26 in a freely rolling manner, And an annular outer ring 28. Further, the inner ring raceway of each thrust ball bearing 24 is formed on the outer side surface (large end surface) of each power roller 11, and the outer ring raceway is formed on the inner side surface of each outer ring 28.

  The thrust needle bearing 25 is sandwiched between the inner surface of the support plate portion 16 of the trunnion 15 and the outer surface of the outer ring 28. Such a thrust needle bearing 25 supports the thrust load applied to each outer ring 28 from the power roller 11, while the power roller 11 and the outer ring 28 swing around the base end portion 23 a of each displacement shaft 23. Allow.

  Further, driving rods (trunnion shafts) 29 and 29 are provided at one end portions (lower end portions in FIG. 8) of the trunnions 15 and 15, respectively, and a driving piston ( Hydraulic pistons) 33, 33 are fixed. Each of these drive pistons 33 and 33 is oil-tightly fitted in a drive cylinder 31 constituted by an upper cylinder body 61 and a lower cylinder body 62. The drive pistons 33 and 33 and the drive cylinder 31 constitute a drive device 32 that displaces the trunnions 15 and 15 in the axial direction of the pivots 14 and 14 of the trunnions 15 and 15.

  In the case of the toroidal continuously variable transmission configured as described above, the rotation of the input shaft 1 is transmitted to the input side disks 2 and 2 via the pressing device 12. Then, the rotation of the input side disks 2 and 2 is transmitted to the output side disks 3 and 3 via the pair of power rollers 11 and 11, and the rotation of the output side disks 3 and 3 is further transmitted to the output gear 4. It is taken out more.

When changing the rotational speed ratio between the input shaft 1 and the output gear 4, the pair of drive pistons 33, 33 are displaced in opposite directions. As the drive pistons 33 and 33 are displaced, the pair of trunnions 15 and 15 are displaced in directions opposite to each other. For example, the power roller 11 on the left side in FIG. 8 is displaced to the lower side in the figure, and the power roller 11 on the right side in the figure is displaced to the upper side in the figure.
As a result, the peripheral surfaces 11a and 11a of the power rollers 11 and 11 act on contact portions of the input side disks 2 and 2 and the inner side surfaces 2a, 2a, 3a and 3a of the output side disks 3 and 3, respectively. The direction of the tangential force changes. As the direction of the force changes, the trunnions 15 and 15 swing in opposite directions around the pivots 14 and 14 (tilt center O ₂ ) pivotally supported by the yokes 23A and 23B ( Tilt).

  As a result, the contact position between the peripheral surfaces 11a and 11a of the power rollers 11 and 11 and the inner surfaces 2a and 3a changes, and the rotational speed ratio between the input shaft 1 and the output gear 4 changes. Further, when the torque transmitted between the input shaft 1 and the output gear 4 fluctuates and the amount of elastic deformation of each component changes, the power rollers 11 and 11 and the outer rings attached to the power rollers 11 and 11 will be described. 28 and 28 are slightly rotated around the base end portions 23a and 23a of the displacement shafts 23 and 23, respectively. Since the thrust needle bearings 25 and 25 exist between the outer side surfaces of the outer rings 28 and 28 and the inner side surfaces of the support plate portions 16 constituting the trunnions 15 and 15, respectively, the rotation is performed smoothly. Is called. Therefore, as described above, the force for changing the inclination angle of each displacement shaft 23, 23 can be small.

  By the way, in such a toroidal type continuously variable transmission, it is necessary to generate an appropriate pressing force at the contact point between the disks 2 and 3 and the power roller 11 in accordance with the transmitted power in order to transmit the power. In this case, if the toroidal continuously variable transmission is in operation, a pressing force can be generated by the above-described loading cam type pressing device 12 or a loading piston using hydraulic pressure. When the continuously variable transmission is not in operation, the above-described loading cam and loading piston do not function, so that the continuously variable transmission is pressed by the above-described disc spring 8 provided between the cam plate 7 and the flange 1d of the input shaft 1. Generating power.

Here, when a large torque is to be transmitted, the necessary pressing force also increases, and elastic deformation occurs in each part of the toroidal-type continuously variable transmission. As a result, the power roller 11 is displaced in the direction of the rotation axis and away from the input shaft 1. In this case, the above-described conventional toroidal-type continuously variable transmission, that is, a toroidal in which the tilt center O ₂ of the power roller 11 and the curvature center O _{1 of the} disks ₂ and 3 coincide as shown in FIG. In the type continuously variable transmission, the contact point opening angle θ ₀ , that is, the power roller 11 and the disks 2 and 3, due to the above-described displacement of the power roller 11 when a large torque is transmitted at any gear ratio. A line L3 passing through the intersection Q between the tangents L1 and L2 at the contact points P ₁ and P ₂ with the center O ₁ (O ₂ ) is a contact point near the center of the inner surface of the disk (P _{1 in} FIG. 9). the angle theta ₀ formed between the normal line increases in, therefore, a risk and the contact point P _1, P ₂ will fall off from the traction surface 2a, 3a of the disk 2, the contact point normal force Fc is reduced P _1, P Surface pressure there was a fear that caused the slip by lowered.

  Therefore, in the conventional toroidal-type continuously variable transmission, the outer diameters of the discs 2 and 3 are increased in order to increase the strength of the components in order to reduce the elastic deformation and to increase the effective range of the traction surfaces 2a and 3a. Various measures have been taken, such as, but this resulted in new problems such as increased weight and size.

Therefore, in order to overcome the problems in these conventional structures, even if the power roller 11 is displaced in a direction away from the input shaft 1 when transmitting a large torque, the tilt center O ₂ of the power roller 11 and the disc 2, as third and center of curvature O ₁ is not greatly different, are tilting center O ₂ was allowed to offset the center of curvature O ₁ of the disk 2, 3 structure of advance power rollers 11 have been proposed.

For example, in Patent Document 1 and Patent Document 2, the tilt center O ₂ of the power roller 11 is offset so as to be closer to the input shaft 1 than the curvature center O _{1 of the} disks 2 and 3.

Further, Patent Document 3 discloses that a high speed side shifting state (High side: the peripheral surfaces 11 a and 11 a of the power rollers 11 and 11 are closer to the outer periphery of the inner side surface 2 a of the input side disc 2 and the inner side surface 3 a of the output side disc 3. In the direction of the rotation axis of the power roller 11 and away from the input shaft 1 from the center of curvature O ₁ of the disks ₂ and 3. An offset structure is disclosed.

JP-A-6-280959 JP 2005-249070 A JP 2004-68942 A

However, in the structures of Patent Document 1 and Patent Document 2, since the power roller 11 is offset so as to approach the input shaft 1 at all speed ratios, the low speed side (Low side: the peripheral surface 11a of each of the power rollers 11, 11). , 11a is a high speed side that does not require a large pressing force as compared with a shift state in which the central portion of the inner side surface 2a of the input side disk 2 and the outer peripheral portion of the inner side surface 3a of the output side disk 3 are in contact with each other. Then, the contact point opening angle θ ₀ tends to be small. As a result, the normal force Fc tends to be large, and the thrust force applied to the bearing inside the power roller 11 increases, which may reduce the efficiency and life of the bearing. And also in the contact point of the power roller 11 which is a power transmission part, and the discs 2 and 3, there exists a possibility of causing a fall of efficiency and a lifetime because surface pressure increases.

On the other hand, according to the structure of Patent Document 3, since the amount of approach of the power roller 11 to the input shaft 1 is smaller on the high speed side than on the low speed side, reduction in efficiency and life of the power roller 11 on the high speed side is suppressed. be able to. However, in the structure of Patent Document 3, as in the structures of Patent Document 1 and Patent Document 2 described above, the power roller 11 is offset so as to approach the input shaft 1 at all speed ratios. In comparison, the contact point opening angle θ ₀ tends to be small on the high speed side that does not require a large pressing force. As a result, the normal force Fc tends to be large, and the thrust force applied to the bearing inside the power roller 11 increases, which may reduce the efficiency and life of the bearing. And also in the contact point of the power roller 11 which is a power transmission part, and the discs 2 and 3, there exists a possibility of causing a fall of efficiency and a lifetime because surface pressure increases.

Further, in addition to the above problems associated with the contact point opening angle θ ₀ and the normal force Fc, in the conventional toroidal type continuously variable transmission, the traction coefficient of traction oil used for power transmission decreases in a low temperature environment. If the required pressing force cannot be obtained by the disc spring 8 when starting the engine in a low temperature environment, the power roller 11 which is a power transmission unit of the toroidal continuously variable transmission There is a possibility that slip occurs at the contact point between the disk 2 and the disk 2 and 3, and the power transmission section is damaged.

  As one means for solving this problem, it is conceivable to provide a disc spring 8 that generates a higher pressing force. However, strengthening the disc spring 8 does not require a larger pressing force than the low speed side. This means that the pressing force becomes excessive, and the efficiency of the toroidal type continuously variable transmission is greatly impaired. In particular, on the high speed side, the engine speed can be reduced during high-speed cruise travel (constant speed travel), so an improvement in fuel consumption can be expected. However, in this travel state, the load is small and the necessary pressing force is spring force. Therefore, the pressing force is excessive, and the efficiency of the variator may be reduced, and the fuel efficiency may be greatly impaired.

  The present invention has been made in view of the above circumstances, and generates a pressing force sufficient for starting at a low speed side without providing a preload member such as a strong disc spring even in a low temperature environment, The purpose of the present invention is to provide a highly efficient toroidal-type continuously variable transmission that does not cause excessive pressing force.

  To achieve the above object, a toroidal continuously variable transmission according to the present invention includes a first disk coupled to a shaft and rotating integrally with the shaft, and a tiltable structure provided between the first disk and the first disk. And a second disk that receives the rotational force of the first disk at a predetermined speed ratio through a power roller, and the first disk and the second disk have inner surfaces having a predetermined curvature. In the toroidal-type continuously variable transmission provided concentrically and rotatably in the opposed state, the tilting center of the power roller is in a direction parallel to the axis with respect to the center of curvature of the disc. And offset in the direction approaching the second disk.

  In the present invention, by offsetting the tilt center of the power roller in the direction parallel to the axis and approaching the second disk with respect to the center of curvature of the disk, on the low speed side, the power roller approaches the axis. It is offset and does not change at a 1: 1 gear ratio (the power roller is not offset), and on the high speed side, the power roller is offset in a direction away from the input shaft. As a result, even if a preload member such as a strong disc spring is not provided in a low temperature environment, starting at a low temperature environment requires a large pressing force on the power transmission part between the power roller and the disk. Can be generated at a gear ratio of 1: 1 and a high speed side (the pressing force does not change at a gear ratio of 1: 1, but tends to decrease on the high speed side). To achieve a highly efficient toroidal continuously variable transmission.

  In the above configuration of the present invention, the control unit further includes a control unit that controls driving of the transmission and a hydraulic loading mechanism that presses the first disk toward the second disk, and controls the driving of the transmission. When the engine is started, the low-speed side shifting state is maintained until the loading pressure of the hydraulic loading mechanism completely rises, and when the engine is stopped, the engine is controlled to stop in the low-speed side shifting state. preferable.

According to such a configuration, in a low-temperature environment, the gear is shifted to the low speed side before the engine is stopped, the engine is stopped after the shift is completed, and when the engine is started, the low speed side is changed until the pressing force by the loading mechanism is completely generated. By performing the control of maintaining the engine, the engine can be started stably and reliably even in a low temperature environment.
In starting the engine in a low-temperature environment below a predetermined temperature, the control unit, for example, (a) slowly turns the starter motor, (b) maximizes the command value of the loading pressure, and (c) is adjustable. Set the lubrication oil command value to the minimum value.

  According to the present invention, the tilting center of the power roller is offset with respect to the center of curvature of the disk in a direction parallel to the axis and approaching the output side disk. However, it is possible to provide a high-efficiency toroidal continuously variable transmission that generates a pressing force sufficient for starting on the low speed side and does not have an excessive pressing force on the high speed side without providing a preload member such as a strong disc spring.

It is a sectional side view of the toroidal type continuously variable transmission which concerns on embodiment of this invention. FIG. 2 is a plan sectional view of the toroidal continuously variable transmission of FIG. 1. FIG. 2 is a cross-sectional view of a trunnion shaft of the toroidal continuously variable transmission of FIG. 1. It is a conceptual diagram which shows the state by which the tilt center of a power roller is offset with respect to the curvature center of a disk in a cross section. It is a flowchart at the time of engine starting in a low temperature environment. It is a flowchart at the time of an engine stop. It is sectional drawing which shows an example of the conventional toroidal type continuously variable transmission. It is sectional drawing which follows the AA line in FIG. It is a schematic diagram showing a main part configuration of a conventional toroidal type continuously variable transmission in which the tilt center of the power roller and the center of curvature of the disk coincide.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Here, FIG. 1 is a side sectional view of the toroidal type continuously variable transmission according to the embodiment of the present invention, FIG. 2 is a plan sectional view of the toroidal type continuously variable transmission of FIG. 1, and FIG. FIG. 9 is a cross-sectional view of a trunnion shaft of the toroidal continuously variable transmission of FIG. 7. In these drawings, portions common to the conventional toroidal continuously variable transmission shown in FIGS. Is omitted or simplified.

  In the toroidal-type continuously variable transmission according to the present embodiment, the conventional output side disk (second disk) 3 and 3 shown in FIGS. 7 and 8 are integrally formed on the outer peripheral surface of the output side disk 3A. , A power transmission gear (outer peripheral gear) 4A is provided, and an input side disk (first disk) having an input shaft (shaft) 1 and inner surfaces 2a and 2a having a predetermined curvature in a stage before being housed in the casing. 2) 2, 2; output side disk 3A having inner surfaces 3a, 3a having a predetermined curvature, outer peripheral gear 4A, upper and lower yokes 23A, 23B, trunnion 15, power roller 11, drive device 32, hydraulic loading mechanism (hereinafter referred to as "loading mechanism") , A pressing device) 80, a fixing member 52 (upper plate) and the like are integrally assembled to form a variator 43. The variator 43 is accommodated in a casing and attached. It has become the jar.

  In such a variator 43, a lower spherical post 68 fixed to the upper cylinder body 61 and the lower cylinder body 62 constituting the driving cylinder 31 of the driving device 32, and an upper spherical surface fixed to the upper plate 52. The post 64 is a columnar post (support member) 69 integrally joined vertically, and in the variator 43, the pair of columnar posts 69 are the upper plate 52 and the cylinder body of the drive cylinder 31 (the upper cylinder body 61 and the lower cylinder). The body 62) is connected.

  Further, the input shaft 1 penetrates through the upper and lower central portions of the columnar post 69. A pair of input side disks 2 and 2, an output side disk 3 </ b> A, a pressing device 80, and the like are supported on the input shaft 1.

  The output side disk 3A is supported by the input shaft 1 via a radial needle bearing 35 so as to be relatively rotatable. Further, the output side disk 3A is disposed between the pair of columnar posts 69, 69, and the output side disk 3A is positioned in the axial direction and supported rotatably around the axis on both ends in the axial direction of the output side disk 3A. A thrust bearing 60 is provided. That is, the thrust bearing 60 is disposed between the columnar post 69 and the small-diameter side end of the output side disk 3A, thereby restricting the position of the output side disk 3A along the axial direction of the input shaft 1 and The output side disk 3A is allowed to rotate about its axis.

  As shown in FIG. 2, a support shaft 23c is formed integrally with the outer ring 28 of the thrust ball bearing 24 that receives the thrust load of the power roller 11. Further, the inner side surface of the support plate portion 16 of the trunnion 15 is a part of a convex cylindrical surface along the axial direction of the pivot 14. Further, on the back side of the outer ring 28 facing the inner side surface of the support plate portion 16, a concave cylindrical surface that abuts against the protruding cylindrical surface of the support plate portion 16 is provided. The power roller 11 can swing along the substantially axial direction of the input shaft 1 by swinging with the power roller 11 so as to swing the head.

  The pressing device 80 is arranged on the back side (left side) of the left input side disk 2 (of course, it may be the right input side disk 2 as shown in FIG. 4), and the left end of the input shaft 1. A first cylinder part 81 coupled to the part, a second cylinder part 82 provided integrally with the input side disk 2, an annular first piston part 83, and an annular second piston part 84. Yes.

  A space surrounded by the inner surface of the first cylinder portion 81, the first piston portion 83, and a part of the outer peripheral surface of the input shaft 1 constitutes a first hydraulic chamber 85. The space surrounded by the inner peripheral surface of the second cylinder portion 82, the second piston portion 84, the back surface of the input side disk 2, and a part of the outer peripheral surface of the input shaft 1 is a second hydraulic chamber 90. Is configured.

  A part of the first hydraulic chamber 85 is used to insert a disc spring (preload member) 94 between the first piston portion 83 and the first cylinder portion 81 for applying a preload. The disc spring 94 urges the first piston portion 83 that is movable along the input shaft 1 toward the input cylinder 2 with respect to the first cylinder portion 81.

  In such a pressing device 80, pressure oil of a predetermined pressure is fed into the first hydraulic chamber 85 and the second hydraulic chamber 90. Then, a force is generated in the hydraulic chambers 85 and 90 in the direction in which the axial dimensions of the hydraulic chambers 85 and 90 increase.

  When pressure oil is fed into the first hydraulic chamber 85, the first piston part 83 is pressed to the right side (input side disk 2 side) in FIG. The input side disk 2 is pressed to the right side via the two cylinder part 82. At the same time, the first cylinder portion 81 is pressed to the left side, and the input shaft 1 integrated with the first cylinder portion 81 moves to the left side, so that it is located on the right side and is axially outward (right side) with respect to the input shaft 1. The input side disk 2 provided with restricted movement is pressed toward the output side disk 3A.

  On the other hand, when the pressure oil is fed into the second hydraulic chamber 90, the second piston portion 84 is restricted from moving to the left in FIG. The forces generated in both the hydraulic chambers 85 and 90 in this way press the input side disk 2 toward the output side disk 3A.

  In this way, the traction portion of the power roller 11 is brought into rolling contact with both the input / output side disks 2 and 3A, and the rotational driving force of the input side disk 2 is transmitted to the output side disk 3A at a desired reduction ratio.

Here, in the toroidal type continuously variable transmission according to the present embodiment, as described above, the input side disk 2 and the output side disk 3A have the inner side surfaces 2a, 3a having a predetermined curvature facing each other. Although provided concentrically and rotatably, the tilt center O ₂ of the power roller 11 sandwiched between the disks 2 and 3A is parallel to the input shaft 1 with respect to the center of curvature O ₁ of the disks 2 and 3. Offset in a direction that approaches the output side disk 3A. FIG. 4 conceptually shows a state in which the tilt center O ₂ of the power roller 11 is offset with respect to the curvature center O ₁ of the disks 2 and 3.

In FIG. 4, as an example, the support holes 18 of the yokes 23 </ b> A and 23 </ b> B into which the tilt bearings of the power roller 11 (the pivot 14 of the trunnion 15) are fitted are offset (the support holes 18 ′ in this embodiment are shown in FIG. 8). 4 is offset in a direction parallel to the input shaft 1 and approaching the output side disk 3A from the conventional support hole 18... In FIG. ), The tilting center O ₂ of the power roller 11 is offset by δ in the direction parallel to the input shaft 1 and approaching the output side disk 3A with respect to the center of curvature O _{1 of the} disks 2 and 3. The In this case, the power rollers 11 to be offset need not be all but can be arbitrarily set.

In this embodiment, in addition to the offset of the tilt center O ₂ of the power roller 11, a control unit (not shown) that controls the drive of the transmission operates when the engine starts (the engine rotates by itself). For the first time, control is performed so that the low-speed side shifting state is maintained until the loading pressure of the pressing device 80, which is a hydraulic loading mechanism, completely rises, and the engine is stopped in the low-speed side shifting state when the engine is stopped.

  Specifically, the control mode shown in the flowcharts of FIGS. 5 and 6 is realized. That is, FIG. 5 shows a control form at the time of starting the engine in a low temperature environment below a predetermined temperature (specifically, for example, several degrees C.). (Step S1) starts by checking whether or not the current state is in a low temperature environment by a temperature sensor or the like (Step S2). If it is not under a low temperature environment, the engine start is allowed as it is (step S9). When the engine is started in a low temperature environment, it is assumed that the engine is started in a cold region where so-called snow falls.

  On the other hand, in a low temperature environment, first, the command value of the loading pressure (loader pressure) of the loading mechanism (pressing device 80) is set to the maximum value (step S3), and the loader pressure rises as quickly as possible. Goal. Next, the command value for the supply amount of the lubricating oil is set to the minimum value (step S4), and the oil is supplied with priority over the loading mechanism. Thereafter, the starter motor is slowly rotated to reduce the torque transmitted by the toroidal continuously variable transmission as much as possible (step S5). Then, whether or not the loading pressure has risen completely is checked by a pressure sensor or the like (step S6). If the loading pressure does not rise completely, the shifting state of the toroidal continuously variable transmission is maintained on the low speed side. (Step S7). On the other hand, if the loading pressure has risen completely, the start of shifting is permitted (step S8).

  FIG. 6 shows a flowchart when the engine is stopped. Note that the control mode of this flowchart is executed regardless of whether or not it is in a low temperature environment.

  As shown in the figure, in this control mode, the shift state is forcibly switched to the low speed side when the engine is stopped (step S31). Specifically, when the engine is stopped, it is always checked whether or not the gear ratio is on the low speed side (step S32). If it is not on the low speed side, the gear shift is continued on the low speed side (step S33). Only when it is determined that the speed is low, the engine is stopped (step S34).

As described above, according to the present embodiment, the tilt center O ₂ of the power roller 11 is parallel to the input shaft 1 with respect to the curvature center O _{1 of the} disks 2 and 3A and approaches the output disk 3A. Therefore, on the low speed side, the power roller 11 is offset in a direction approaching the input shaft 1 and does not change at a transmission ratio of 1: 1 (the power roller 11 does not offset). The roller 11 is offset in a direction away from the input shaft 1. As a result, even if a strong disc spring 94 is not provided for a low temperature environment, a large pressing force is required on the power transmission portion between the power roller 11 and the disks 2 and 3 on the low speed side. Sufficient pressing force can be generated for start-up, and the pressing force does not become excessive at the gear ratio of 1: 1 and the high speed side (the pressing force does not change at the gear ratio of 1: 1, but decreases at the high speed side. It is possible to realize a highly efficient toroidal continuously variable transmission with a structure.

  In this embodiment, in a low-temperature environment, the gear is shifted to the low speed before the engine is stopped, the engine is stopped after the shift is completed, and the low speed is maintained until the pressing force by the loading mechanism is completely generated when the engine is started. Since the control of continuing is performed, the engine can be started stably and reliably even in a low temperature environment.

The present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the scope of the invention. For example, in a toroidal type continuously variable transmission, the input / output relationship between the input side disk and the output side disk may be reversed. Therefore, the present invention can also be applied when the input side disk 2 and the output side disk 3 are interchanged.
The present invention can also be applied to toroidal continuously variable transmissions such as double cavity half toroidal continuously variable transmissions, single cavity half toroidal continuously variable transmissions, full toroidal continuously variable transmissions, and the like.

1 Input shaft (axis)
2 Input disk (first disk)
3A output side disk (second disk)
11 Power roller 80 Pressing device (hydraulic loading mechanism)
O ₁ disc curvature center O ₂ power roller tilt center

Claims (3)

A first disk coupled to a shaft and rotating integrally with the shaft and a tiltable power roller provided between the first disk and a rotational force of the first disk at a predetermined gear ratio. A first disk and a second disk, the first disk and the second disk being provided concentrically and rotatably with each inner surface having a predetermined curvature facing each other. In a step transmission,
A toroidal continuously variable transmission characterized in that the tilting center of the power roller is offset with respect to the center of curvature of the disk in a direction parallel to the axis and approaching the second disk. Machine. A control unit that controls drive of the transmission; and a hydraulic loading mechanism that presses the first disk toward the second disk;
The control unit controls to keep the low speed side shifting state until the loading pressure of the loading mechanism completely rises when starting the engine, and to stop the engine in the low speed side shifting state when the engine is stopped. The toroidal continuously variable transmission according to claim 1.   In starting the engine in a low temperature environment below a predetermined temperature, the control unit (a) slowly rotates the starter motor, (b) maximizes the command value of the loading pressure, and (c) adjustable lubricating oil. The toroidal continuously variable transmission according to claim 2, wherein at least one of the command value of the quantity is made a minimum value.

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