JP3399074B2 - Friction wheel type continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement proposal of a friction wheel type continuously variable transmission which aims at improving shift control accuracy. 2. Description of the Related Art Generally, the most common toroidal type continuously variable transmission is described in Japanese Patent Application Laid-Open No. 1-295070. As shown in FIG. 4 and FIG. 5, the input / output cone disks 1 and 2 arranged coaxially and the power are transferred by frictional engagement between the input / output cone disks.
Two power rollers 3 which are friction wheels arranged around the rotation axis O ₁ of the input / output cone disk, a trunnion 4 as a friction wheel support member which rotatably supports these power rollers 3 individually, The upper end portions and the lower end portions of the trunnions 4 adjacent to each other are connected to each other.
Is provided with an upper link 7 and a lower link 8 connected via spherical joints 5 and 6 so as to be stroked synchronously in the direction of the swing axis (O ₃ ) orthogonal to the rotation axis O ₂ of the power roller 3. . Then, a servo piston 9 is coaxially extended at the lower end of the trunnion 4 to cause the trunnion 4 to perform a stroke, thereby causing the power roller 3 to tilt around the oscillating axis (O ₃ ). The vehicle-type continuously variable transmission can perform a predetermined shift. The operation of such a friction wheel type continuously variable transmission will be briefly described. In FIG. 4, rotation from an input shaft 10 is transmitted to an input cone disk 1 via a loading cam 11, and this rotation is further transmitted to a power roller. 3 to the output cone disk 2, which can then be removed via the output gear 12. During this time, the loading cam 11
The power roller 3 generates thrust according to the transmission torque and
Is pressed between the input and output cone disks 1 and 2, and the above-described transmission is enabled by the pressing force F ₁ from the input and output cone disks 1 and 2 to the power roller 3. In shifting, the servo piston 9 fitted in the servo piston body 13 in FIG.
By response to pressure command from the oil passage provided in the control valve body 14, thereby stroke the trunnions 4 in the direction of the swing axis O _3. By this time the power rollers 3 are offset axis of rotation O ₂ from the cone disc rotation axis O _1, is tilted about the swing axis O ₃ receives the swinging force component from the cone disc 1, the friction The gear ratio of the vehicle-type continuously variable transmission can be changed. When the predetermined gear ratio is reached, the trunnion 4 is returned to the original stroke position via the servo piston 9 by well-known gear ratio feedback control, whereby the predetermined gear ratio can be maintained. [0005] The present invention is to provide, however, in the conventional friction wheel continuously variable transmission as represented by the resultant force F of the pressing force F ₁ from the input and output cone discs 1 and 2 to the power rollers 3
₂ causes the following problem when the trunnion 4 is bent between articulation points with the upper link 7 and the lower link 8, that is, between the spherical joints 5 and 6. That is, the bending deformation causes the servo piston 9 to tilt so that its axis is shifted from O ₃ to O ₄ shown in FIG. 5, and at this time, the servo piston 9 guides this. The servo piston body 13 and the hole wall of the control valve body 14 interfere with each other. This interference imparts resistance to the operation of the servo piston 9 and hinders it, causing hysteresis in the shift characteristics and causing adverse effects such as a reduction in shift control accuracy. The present invention provides a friction wheel type continuously variable transmission in which the interference of the servo piston does not occur even when the trunnion (friction wheel support member) is bent and deformed. The purpose is to eliminate the adverse effects on accuracy. According to the present invention, there is provided an input / output disk arranged coaxially and opposed to each other, and power is generated by frictional engagement between the input / output disks. A plurality of friction wheels arranged around the rotation axis of the input / output disk, a friction wheel support member rotatably supporting each friction wheel, and adjacent ends of the friction wheel support member to perform delivery. A link connected via a spherical joint so that each friction wheel support member is stroked synchronously in a swing axis direction orthogonal to the rotation axis of the friction wheel, and provided at one end of the friction wheel support member. In a friction wheel type continuously variable transmission, a servo piston extending coaxially performs a stroke of the friction wheel support member to cause a tilt around the oscillating axis of the friction wheel, thereby performing a gear shift. By setting a taper surface in the ton, the clearance between the servo piston and the hole wall for guiding the servo piston is increased as the distance from the spherical joint increases. In the present invention, a plurality of friction wheels transfer power by frictional engagement between input and output disks. In addition, when the friction wheel support members that rotatably support each friction wheel are individually stroked by the servo piston in the direction of the oscillating axis orthogonal to the rotation axis of the friction wheel, the friction wheel is swung and input / output is performed. The transmission ratio between the disks can be changed steplessly. During the shift, the link functions to synchronize the strokes of the friction wheel support member, so that the shift control can be accurately performed. By the way, the friction wheel support member is bent and deformed between the spherical joints at both ends by the pressing force inputted from the input / output disk to the friction wheel during the above-mentioned transmission, and even if the servo piston is inclined due to this, , The servo piston,
Since the clearance between the hole and the hole wall that guides the hole is set larger as the distance from the spherical joint increases, the servo piston does not interfere with the hole wall that guides the hole. Therefore, it is possible to eliminate the adverse effect that the shift operation accuracy is reduced, for example, the stroke operation of the servo piston receives resistance during the above-mentioned transmission, causing hysteresis in the shift control characteristics. Further, in the present invention, when the clearance between the servo piston and the hole wall for guiding the same is increased as the distance from the spherical joint is increased, the configuration is particularly improved by setting a tapered surface on the servo piston. Since the present invention is realized, the above operation and effect can be achieved without a large increase in the servo piston machining cost. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a main part of a friction wheel type continuously variable transmission for explaining the principle of the present invention. In this figure, the same parts as those in FIG. 5 are denoted by the same reference numerals. That is, O ₂ indicates the rotation axis of the power roller serving as a friction wheel, and the power roller is rotatable about this axis (O ₂ ) and supported on the trunnion 4 serving as a friction wheel support member. Although not shown, the input and output cone disks (disks) are coaxially opposed to each other by frictionally contacting both sides of the power roller, and the input cone disk is connected to the input shaft via a loading cam. Is connected to the output shaft. The power rollers are arranged in pairs on both sides of the rotation axis of the input / output cone disk.
The upper ends of the trunnions 4 that rotatably support the individual power rollers are connected to each other by upper links 7, and the lower ends of the trunnions 4 are connected to each other by lower links 8. Each of these links 7, 8 pivots in the center to the transmission case and connects to the trunnion 4 via spherical joints 5, 6. At the lower end of the trunnion 4, a servo piston 9 is extended coaxially with the swing axis O ₃ , and the servo piston is sealed in a servo piston body 13 by a seal ring 15. Sliding fit.
The servo piston 9 further has piston rods 9a and 9b integrally, and the piston rods 9a and 9b are inserted into the holes 13a and 13b of the servo piston body 13 and the seal ring 1 is formed.
The servo piston 9 is also guided in the direction of its stroke by penetrating under the sealing by 6, 17. The piston rod 9b further penetrates into the holes 14a and 14b of the control valve body 14 under the sealing by the seal rings 18 and 19, and a part of the hydraulic oil from the oil passage provided in the control valve body 14. Can be supplied to an appropriate place via a chamber between the seal rings 18 and 19. Here, in the present invention, in particular, the clearance between the servo piston 9 and the hole wall for guiding it, that is, the clearance d ₁ between the piston rod 9a and the hole 13a, the clearance between the servo piston body and the cylinder inner wall. d ₂ , piston rod 9b and hole 1
The clearance d ₃ between 3b, the clearance d ₄ between the piston rod 9b and the hole 14a, and the clearance d ₅ between the piston rod 9b and the hole 14b are increased as the distance from the spherical joint 6 increases, and d ₅ > d ₄ > d _3> d _2> d ₁
Set so that. In this configuration, by adjusting the outer diameter according to the corresponding portion of the servo piston 9 as _{shown, d 5> d 4> d} 3> d 2> or to d ₁ and so as, holes corresponding to the place It is needless to say that the setting may be performed by adjusting the inner diameter of. The friction wheel type continuously variable transmission having the above-described structure to which the principle of the present invention is added performs the following operations. Individually trunnion 4, supporting the power roller to be freely rotatable about the axis O ₂ is for transferring power by frictional engagement between the input and output cone discs. During this time, when the trunnions 4 are individually stroked by the servo piston 9 in the direction of the oscillating axis (O ₃ ) orthogonal to the power roller rotation axis O ₂ , the power roller is swung around the coaxial line and the input / output disk is driven. The transmission ratio between them can be varied steplessly. During this shift, the upper link 7 and the lower link 8 function to synchronize the strokes of the trunnion 4 so that shift control can be accurately performed. Here, the trunnion 4 is bent and deformed between the spherical joints 5 and 6 at both ends by the resultant force F ₂ of the pressing force F ₁ (see FIG. 4) input from the input / output disk to the power roller during the above-described transmission. that time, the servo piston 9 is tilted about the position of the spherical joint 6 as shown in FIG. 2, tilted so that its axis O ₃ is a position indicated by O ₄ in FIG.
Thus, a clearance d ₁ to d ₅ according to the present invention,
And large enough furthest from spherical joint 6, d _5> d _4>
Since d ₃ > d ₂ > d ₁ , the servo piston 9 does not interfere with the hole wall for guiding the servo piston 9 even with the inclination of the servo piston 9 shown in FIG. Therefore, the stroke operation of the servo piston 9 receives resistance during the above-mentioned transmission, and it is possible to eliminate adverse effects such as lowering the shift control accuracy, such as causing hysteresis in the shift characteristics. [0020] For convenience for easy understanding of the principles of the present invention in the above configuration, the clearance d ₁ to d _5, and large enough furthest from spherical joint _{6, d 5> d 4>} d 3>
In setting d ₂ > d ₁ , it has been described that the clearance is set by adjusting the outer diameter related to the corresponding portion of the piston rods 9 a and 9 b or the inner diameter of the corresponding hole. As shown by θ in FIG. 3 showing an embodiment of the present invention, the piston rods 9a, 9b
Is tapered in the direction of the rod axis as a whole, whereby d ₅ > d ₄ > d ₃ > d ₂ > d ₁
By setting the clearance as described above, the above-described effects can be obtained. Here, the outer peripheral surface taper angle θ of the piston rods 9a and 9b is set to a value slightly larger than the maximum inclination angle of the servo piston 9 accompanying the deformation of the trunnion 4. According to the friction wheel type continuously variable transmission of the present invention, the clearance between the servo piston and the hole wall for guiding the servo piston can be reduced.
As the distance increases from the spherical joint, the friction wheel support member bends and deforms between the spherical joints at both ends due to the pressing force input to the friction wheel from the input / output disk during the transmission operation of the friction wheel type continuously variable transmission. As a result, even if the servo piston is tilted due to this, the servo piston does not interfere with the hole wall that guides it, and the stroke operation of the servo piston receives resistance during the above transmission, resulting in hysteresis. Thus, it is possible to eliminate the adverse effect that the shift control accuracy is reduced due to the above-mentioned factors. According to the present invention, by further providing a tapered surface on the servo piston, the clearance between the servo piston and a hole wall for guiding the servo piston is moved away from the spherical joint as described above. Since the size is increased, the above-described effects can be achieved without a large increase in the processing cost of the servo piston.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial vertical sectional side view showing a main part of a friction wheel type continuously variable transmission explaining the principle of the present invention. FIG. 2 is an explanatory diagram of an operation of the friction wheel type continuously variable transmission. FIG. 3 is a sectional view showing a servo piston portion of the friction wheel type continuously variable transmission according to the embodiment of the present invention. FIG. 4 is a partial cross-sectional side view illustrating a conventional friction wheel type continuously variable transmission. FIG. 5 is a vertical sectional side view showing a trunnion and a servo piston portion. [Description of Signs] 1 Input cone disk 2 Output cone disk 3 Power roller (friction wheel) 4 Trunnion (friction wheel support member) 5 Spherical joint 6 Spherical joint 7 Upper link 8 Lower link 9 Servo piston 10 Input shaft 11 Loading cam 12 Output shaft 13 Servo piston body 14 Control valve body

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 13/00-15/56 F16J 1/00-1/24 F16J ⁷ /00-10/04

Claims (1)

(57) [Claims 1] An input / output disk arranged coaxially opposed to and around a rotation axis of the input / output disk so as to transfer power by frictional engagement between the input / output disks. A plurality of friction wheels arranged, a friction wheel support member rotatably supporting each friction wheel, and mutually adjacent ends of the friction wheel support members, each friction wheel support member being a rotation axis of the friction wheel. And a link connected via a spherical joint so as to be stroked synchronously in the direction of the swing axis orthogonal to the axis, and a servo piston coaxially extended to one end of the friction wheel support member. In the friction wheel type continuously variable transmission that performs a stroke to cause a tilt around the oscillating axis of the friction wheel and performs a gear shift, by setting a tapered surface on the servo piston,
The servo piston, the clearance between the bore wall for guiding the servo piston, friction wheel continuously variable transmission, characterized in that it has increased as cull far changed from the spherical joint.