JP2003232415A - Toroidal type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain occurrence of spinning of a roller on a toroidal type continuously variable transmission. <P>SOLUTION: A contact ellipse of a traction contact part A of raceway surfaces 4a, 7a of input and output discs 4, 7 and an outer peripheral end surface of the roller 13 is constituted so that an elliptical ratio (κ) (= length of major axis/length of minor axis) is 1≤κ≤3 by specifying the relative rolling direction of the roller 13 as the major axis. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toroidal type continuously variable transmission. 2. Description of the Related Art In a toroidal type continuously variable transmission, a roller is sandwiched between track surfaces of an input disk and an output disk facing each other with a predetermined force, and the roller and each disk are connected to each other. The torque is transmitted between the two disks by the traction force between the two disks. However, a phenomenon in which the roller spins at the traction contact portion between each disk and the roller is observed. Such a spin is provided with an angle between the rotation axis of the disk and the rotation axis of the roller, and the traction contact portion has a width in a direction orthogonal to the relative rolling direction (driving direction) of the roller. It is geometrically inevitable. And the spin is
Since the movement has a rotational sliding component in a direction orthogonal to the relative rolling direction of the rollers, power loss occurs and heat is generated. In particular, the spin is larger in the full toroidal type continuously variable transmission than in the half toroidal type continuously variable transmission (7 times (199 times that of the half toroidal type continuously variable transmission).
In May 2006, the Society of Automotive Engineers of Japan "Academic Lectures
62, p. 121, "Geometrical Study on Toroidal-Type Continuously Variable Transmission")), not only the power loss is increased, but also the life of the roller is shortened by heat generation. [0003] In view of the above-mentioned conventional problems, an object of the present invention is to suppress occurrence of spin of a roller in a toroidal-type continuously variable transmission. In the toroidal type continuously variable transmission according to the present invention, a roller is sandwiched between track surfaces of an input disk and an output disk facing each other with a predetermined force. In the toroidal type continuously variable transmission that transmits torque between the two disks by the traction force between the rollers, the contact ellipse of the traction contact portion between the raceway surface of each disk and the outer peripheral end surface of the roller indicates the relative rolling of the roller. The direction is the major axis, and the elliptic ratio κ (= the major axis length /
(The length of the short axis) is 1 ≦ κ ≦ 3. In the toroidal type continuously variable transmission configured as described above, by setting the elliptic ratio κ to the above range, the power transmission at the traction contact portion exhibits directivity in the long axis direction, that is, in the relative rolling direction of the rollers. The occurrence of spin of the roller is suppressed. FIG. 1 is a schematic diagram of a toroidal-type continuously variable transmission according to an embodiment of the present invention. The variator 1 which is a main part of the toroidal-type continuously variable transmission is provided with an input shaft 3 which is driven to rotate by an output shaft (not shown) of the engine. Input disks 4 are supported by spline coupling near both ends of the input shaft 3, respectively.
Each input disk 4 rotates integrally with the input shaft 3. A concave curved track surface 4 a is formed on one side surface of each input disk 4. In addition, the movement of each input disk 4 in directions away from each other is restricted by a locking ring 5 fixed to the input shaft 3. An output section 8 is provided at the axial center of the input shaft 3 with an output member 6 having a sprocket gear formed on the outer periphery and an output disk 7 supported by the output member 6 so as to be integrally rotatable. Are provided so as to be rotatable relative to the input shaft 3. Track surface 4 of input disk 4
A concave curved track surface 7a is formed on one side surface of the output disk 7 opposite to a. The output shaft 10 of the variator 1 that transmits power to the drive wheels is provided in parallel with the input shaft 3, and has a pair of sprocket wheels 10 a at positions corresponding to the output members 6. A chain 9 is mounted on the output member 6 and the sprocket wheel 10a.
The power is taken out to zero. [0007] The output disk 7 is incorporated in the output member 6 in a state in which fine movement in the axial direction is permitted, and a back-up plate 11 is disposed on the back surface thereof with a gap provided therebetween. The gap is sealed by a casing 12 and a seal (not shown), and by supplying hydraulic pressure to the gap, the output disk 7 is urged toward the opposite input disk 4 to apply a predetermined terminal load. I have. The orbital surfaces 4 of the input disks 4 facing each other
a and a track surface 7a of the output disk 7 are formed as toroidal gaps.
Three (only two of them are shown) disk-shaped rollers 13 that rotate while being in pressure contact with the respective raceway surfaces 4a and 7a are arranged at equal circumferential intervals. Each roller 13 is rotatably supported by a carriage 14 and its rotation axis is tiltably supported. A driving force by hydraulic pressure is applied to the carriage 14 in the direction of pushing and pulling the rollers 13. In the variator 1, a pair of input disks 4 is supplied to each of the corresponding output disks 7.
The torque is transmitted via the rollers 13. When transmitting the torque, a reaction force is generated in the roller 13, and the driving force applied to the carriage 14 supports the reaction force. If an imbalance occurs between the reaction force and the torque required to drive the output disk 7, the roller 13 changes the shaft angle to eliminate the imbalance. For example, a change in the traveling load or an increase or decrease in the accelerator pedal causes the carriage 1
When a force occurs such that the roller 4 is pushed back or pulled out against the driving force of the hydraulic pressure, the shaft angle of the roller 13 changes (see the two-dot chain line in FIG. 1), and the gear ratio is increased or decreased. , The torque output from the variator 1 changes. That is, the change in the ratio in the variator 1 is
This is achieved only by adjusting the driving force applied to the carriage 14 and responding to the external resistance. Hydraulic oil that forms an oil film between the roller 13 and each of the disks 4 and 7 is supplied to the surface of the roller 13 via an internal passage (not shown) of the carriage 14. FIG. 2A shows the orbital surfaces 4a, 4b of the disks 4, 7 in the variator 1 configured as described above.
FIG. 7 is a diagram showing a simplified relationship between 7a and a roller 13; If the direction parallel to the input shaft 3 (FIG. 1) is the X direction, the tangential direction of the roller 13 orthogonal to the X direction is the Y direction, and the direction orthogonal to both the X and Y directions is the Z direction, (b)
FIG. 3A is a view of the track surfaces 4a and 7a and a roller 13 viewed from the Z direction in FIG. The Y direction (including the -Y direction) is a direction in which the roller 13 rolls relatively to the raceway surfaces 4a and 7a (it only rotates without rolling when viewed from an absolute position). In a state where a predetermined terminal load is applied, a portion where the raceway surfaces 4a, 7a and the roller 13 come into contact with each other via an oil film, that is, a traction contact portion A is formed on the YZ plane as shown in FIG. An ellipse is formed. The shape and dimensions of the contact ellipse are determined by the radius of curvature of the tip of the roller 13 on the XZ plane in FIG.
The diameter of the roller 13 in the (Y) direction, the curvature of the concave curvature of the orbital surfaces 4a and 7a of each disk, the inclination of the roller 13 around the Y axis (geometric relationship of the contact portion), and the terminal load of the disk (Contact load), Young's modulus, Poisson's ratio, etc. of the material of the roller 13 and the disks 4, 7 (mechanical characteristic value of the contact portion)
The shape (elliptic ratio) of the contact ellipse is basically determined by the above geometric relationship. In addition, the diameter of the roller 13, the curvature of the concave curvature of the raceway surfaces 4a and 7a, and the contact load are generally determined by a transmission ratio required for the transmission, a required torque, and an outer dimension limit. . Therefore, when these dimensions, load, and the like are kept constant and only the radius of curvature of the tip of the roller 13 on the XZ plane is changed, the contact ellipse becomes longer in the Z direction as the radius of curvature increases. vice versa,
As the radius of curvature becomes smaller, the contact ellipse becomes shorter in the Z direction. Therefore, the inventor of the present invention examined the relationship between the shape of the contact ellipse and the mechanical efficiency (torque transmission efficiency) by experiments by variously changing the radius of curvature of the tip of the roller 13. The experimental conditions are as follows. Number of rotations of input shaft 3 and output shaft 10 of variator 1: 2
000 rpm (Keep constant by inverter control.) Temperature of traction contact part A: 120 ° C. (Measure roller surface temperature near A with a thermocouple and control hydraulic oil temperature in oil tank to be constant.) Output torque of output unit 8: 300 Nm Gear ratio: 1 Toroid radius Ra (FIG. 1): 55 mm Toroid radius Rb (FIG. 1): 50 mm Hydraulic oil (lubricating oil): SANTO of traction oil
TRAC50 (manufactured by Finded Corporation) Disk end load F1 (FIG. 1): 54545N Roller driving force F2 (FIG. 1): 1936N Outer diameter of roller 13: 100 mm Radius of curvature at the tip of roller 13: range of 5 to 45 mm (5 mm) FIG. 5 is a schematic configuration diagram of the experimental apparatus. The rotation shaft 22 of the motor 21 whose rotation speed is controlled by the inverter causes the drive shafts 24 and 25 to rotate at the same speed and reverse speed via a transmission 23. The drive shafts 24 and 25 are connected to the input shaft 3 and the output shaft 10 of the variator 1 by couplings 26 and 27, respectively. With such an experimental apparatus, the input shaft 3 and the output shaft 10 of the variator 1 are forcibly rotated at the same rotational speed, and at this time, the torque acting on the input shaft 3 and the output shaft 10 is measured. The mechanical efficiency is (output torque x output speed) / (input torque x input speed)
Ask by On the other hand, the lengths of the major axis and the minor axis of the contact ellipse are
The outer diameter of the roller 13, the radius of curvature of the tip, and the raceway surface 4
It can be obtained by calculating from the radius of curvature (toroid diameter) of a and 7a by the Hertzian contact theory. Therefore, the shape of the contact ellipse is defined by an ellipse ratio κ obtained by κ = (ellipse radius in Y direction / ellipse radius in Z direction). And the radius of curvature of the tip is 5, 10, 15, 20, 25, 30,
FIG. 4 is a graph plotting the relationship between the value of κ and the mechanical efficiency corresponding to the rollers 13 of 35, 40, and 45 mm. That is, the mechanical efficiency increases rapidly as the value of κ increases from around 0,
The rate of increase gradually slowed down and stabilized, peaked, and then gradually declined. The following can be said from this result. (1) When the value of κ is smaller than 1, the mechanical efficiency is poor. (2) When the value of κ exceeds 1, the mechanical efficiency starts to stabilize at a relatively high level. (3) The peak of mechanical efficiency appears when the value of κ is between 2 and 3,
If it exceeds 3, it decreases gradually. On the other hand, if the value of κ exceeds 3, a phenomenon occurs in which the shape of the contact ellipse becomes too thin and the oil film is not formed stably. If the oil film is not formed stably, the roller 13 comes into direct contact with the raceway surfaces 4a, 7a,
A minute peeling of the outer peripheral surface of the roller 13 occurs. On the other hand, if the shape of the contact ellipse is too thin, the rigidity of the contact portion of the roller 13 in the rotation axis direction becomes small, so that stable rolling contact cannot be performed under a large contact load. Alternatively, it can be expected that the roller 13 is likely to be deformed or damaged. From the above description, the contact ellipse is
The relative rolling direction is the major axis, and the elliptic ratio κ is 1 ≦
It has been found that κ ≦ 3 is a preferable range. this is,
This range setting is considered to be the result of the fact that the power transmission at the traction contact portion A exhibits directivity in the long axis direction, that is, the relative rolling direction of the roller, and the spin of the roller 13 is suppressed. In this case, the elliptic ratio κ
Is equal to (length of major axis) / (length of minor axis). By adopting the elliptic ratio κ in this range, the mechanical efficiency is 96%
It is a high value before and after. Improvement in mechanical efficiency as compared with the case where κ is smaller than 1 is nothing less than suppression of spin, and as a result, generation of spin was able to be suppressed. In this embodiment, the elliptic ratio of the contact ellipse in the full toroidal type continuously variable transmission having a relatively large spin has been described. However, the elliptic ratio in the half toroidal type continuously variable transmission is also adopted. A certain effect can be obtained. According to the toroidal type continuously variable transmission of the present invention configured as described above, by setting the elliptic ratio κ in the range of 1 ≦ κ ≦ 3, the occurrence of the spin of the roller is suppressed. And improved mechanical efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a toroidal type continuously variable transmission according to an embodiment of the present invention. FIG. 2 is a simplified diagram showing a relationship between a track surface of each disk and rollers in a variator of the toroidal type continuously variable transmission. FIG. 3 is a diagram showing a contact ellipse at a traction contact portion between a track surface of each disk and a roller. FIG. 4 is a graph showing a relationship between an elliptic ratio κ and mechanical efficiency. FIG. 5 is a schematic configuration diagram showing a variator experimental apparatus. [Description of Signs] 4 Input disk 4a Track surface 7 Output disk 7a Track surface 13 Roller

Claims (1)

Claims: 1. A roller is sandwiched between track surfaces of an input disk and an output disk facing each other with a predetermined force, and torque is transmitted between the disks by a traction force between the roller and each disk. In the toroidal type continuously variable transmission, the contact ellipse of the traction contact portion between the raceway surface of each disk and the outer peripheral end surface of the roller is determined by setting the relative rolling direction of the roller as a long axis, and an elliptic ratio κ (= long The length of the shaft / the length of the short shaft is 1 ≦ κ ≦ 3.