JP2003314646A - Toroidal type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toroidal type continuously variable transmission having an excellent durability and small and light in weight. <P>SOLUTION: The toroidal type continuously variable transmission includes intermediate discs 30 to function as a pair of output discs made from carbon steel containing 0.3-0.5 wt.% carbon. As a result, much carbon can be included in the central part in axial direction of the intermediate discs 30 where carbon, etc., can not be added by a cement quenching process, a carbonitriding quenching process, etc. Therefore, a sufficient hardness is secured to this part, and a sufficient durability can be secured to the intermediate discs 30 whereto a large pressing force and torque are applied from the two side faces 31--in the axial direction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The toroidal type continuously variable transmission according to the present invention is used as a transmission unit constituting an automatic transmission for automobiles or as a transmission for adjusting the operating speed of various industrial machines such as pumps. To use.

[0002]

2. Description of the Related Art A toroidal type continuously variable transmission is known as a kind of transmission unit constituting a transmission for an automobile, and is partially implemented. Such a toroidal type continuously variable transmission, which has already been partially implemented, is a so-called double cavity type in which power transmission from the input section to the output section is divided into two parallel systems. Is. Such a toroidal type continuously variable transmission has hitherto been disclosed in JP-A-2-28394.
It is well known that it is described in a large number of publications such as JP-A-9, JP-A-8-4869 and JP-A-8-61453, but its basic structure will be described with reference to FIG.

The toroidal type continuously variable transmission shown in FIG. 5 has an input rotary shaft 1 corresponding to the rotary shaft described in the claims. An input side disk 2a corresponding to the outer disk described in the claims is provided around the middle portion of the input rotary shaft 1 near the base end (to the left of FIG. 5) and the tip end (to the right of FIG. 5). 2b are supported.
Both of these input side disks 2a, 2b are the input rotary shaft 1 described above.
On the other hand, the input-side inner side surfaces 3 and 3, which are toroidal curved surfaces, are supported via ball splines 4 and 4 in a state of being opposed to each other. Therefore, the both input side disks 2a, 2b are supported around the input rotary shaft 1 so as to be displaceable in the axial direction of the input rotary shaft 1 and rotatable in synchronization with the input rotary shaft 1. .

A rolling bearing 5 and a loading cam type pressing device 6 are provided between the base end of the input rotary shaft 1 and the outer surface of the input side disk 2a. The cam plate 7 that constitutes the pressing device 6 is rotatably driven by the drive shaft 8. On the other hand, a loading nut 9 and a disc spring 10 having a large elastic force are provided between the tip of the input rotary shaft 1 and the outer surface of the other input side disk 2b.

An intermediate portion of the input rotary shaft 1 is provided with a casing 11 (see FIG. 1 which will be described later) accommodating a toroidal type continuously variable transmission.
(See), the through hole 13 provided in the partition wall 12 is inserted. A cylindrical output tube 2 is provided on the inner diameter side of the through hole 13.
8 is rotatably supported by a pair of rolling bearings 14, 14, and an output gear 15 is fixed to the outer peripheral surface of the intermediate portion of the output cylinder 28. Further, the output side disks 16a and 16b are rotatably supported in synchronization with the output cylinder 28 by spline engagement at both ends of the output cylinder 28 at the portions protruding from both outer side surfaces of the partition wall portion 12.

In this state, the output-side inner side surfaces 17, 17 of the output-side disks 16a, 16b, which are toroidal curved surfaces, face the input-side inner side surfaces 3, 3, respectively.
Further, between the inner peripheral surfaces of the both output side disks 16a, 16b, between the portion protruding from the end edge of the output cylinder 28 and the outer peripheral surface of the intermediate portion of the input rotary shaft 1, the needle bearings 18, respectively. 18 is provided for each output side disk 16
While supporting the load applied to a and 16b, the output side disks 16a and 16b can freely rotate and axially be displaced with respect to the input rotary shaft 1.

A plurality of power sources (generally, two or three power sources) are provided around the input rotary shaft 1 in the space (cavity) between the input-side and output-side inner side surfaces 3 and 17, respectively. Rollers 19, 19 are arranged. Each of these power rollers 19, 19 has a spherical convex surface on the circumferential surface 29, 29 that contacts the input-side and output-side inner side surfaces 3, 17, respectively.
Displacement shafts 21, 21 and radial needle bearings 22, 22
The thrust ball bearings 23, 23 and the thrust needle bearings 24, 24 are supported so as to be freely rotatable and slightly swingable. That is, each of the displacement shafts 21 and 21 is an eccentric shaft in which the base half part and the front half part are eccentric to each other. It is swingably supported by a needle bearing.

The power rollers 19, 19 are rotatably supported by the radial needle bearings 22, 22 and the thrust ball bearings 23, 23 on the first halves of the displacement shafts 21, 21. There is. Further, the displacement of each of the power rollers 19 and 19 in the axial direction of the input rotary shaft 1 based on the elastic deformation of each constituent member can be freely performed by the other radial needle bearing and each of the thrust needle bearings 24 and 24. I am trying.

Further, the trunnions 20 and 20 are
The pivots provided at both ends (in the front-back direction in FIG. 5) are supported by supporting plates 25a and 25b (see FIG. 1 described later) installed in the casing 11 so as to be swingable and axially displaceable. . That is, the trunnions 20 and 20 are movably supported in the clockwise and counterclockwise directions in FIG.
An actuator (not shown) is used to displace the pivot in the axial direction (front and back directions in FIG. 5).

When the toroidal type continuously variable transmission configured as described above is in operation, the input side disk 2a is rotationally driven by the drive shaft 8 via the pressing device 6. Since the pressing device 6 rotationally drives the input side disc 2a while generating thrust in the axial direction, the pair of input side discs 2a and 2b including the input side disc 2a are connected to the output side discs 16a, While being pressed toward 16b, they rotate in synchronization with each other. As a result, the rotation of each of the input side disks 2a, 2b causes the power rollers 19, 19 to rotate.
Is transmitted to each of the output side disks 16a and 16b through the output cylinder 28, and is transmitted to each of the output side disks 1 through the output cylinder 28.
The output gear 15, which is connected to 6a and 16b, rotates.

During operation, the thrust generated by the pressing device 6 causes the peripheral surfaces 29, 2 of the power rollers 19, 19 to rotate.
The surface pressure of each contact portion between the inner side surfaces 3 and 17 of the input 9 and the output side is secured. The surface pressure increases as the power (torque) transmitted from the drive shaft 8 to the output gear 15 increases. Therefore, good transmission efficiency can be obtained regardless of the torque change. Further, even when the torque to be transmitted is 0 or very small, the surface pressure of each of the abutting portions is secured to some extent by the preload spring 26 provided on the inner diameter side of the disc leaf spring 10 and the pressing device 6. . Therefore, the torque transmission in each of the contact portions is smoothly performed immediately after the start-up without causing an excessive slip.

When changing the gear ratio between the drive shaft 8 and the output gear 15, the trunnions 20, 20 are displaced in the front-back direction of FIG. 5 by an actuator (not shown). In this case, the trunnion 2 in the upper half of FIG.
0 and 20 and the trunnions 20 and 20 of the lower half are displaced by the same amount in opposite directions. With this displacement,
The direction of the force applied in the tangential direction of the contact portion between the peripheral surfaces 29, 29 of the power rollers 19, 19 and the input-side and output-side inner side surfaces 3, 17 changes. Then, the tangential force causes the trunnions 20, 20 to swing about the pivots provided at both ends thereof.

Along with this swing, each of the above power rollers 1
The positions of the abutting portions of the peripheral surfaces 29, 29 of 9, 9 and the inner side surfaces 3, 17 of the input side and the output side in the radial direction of the inner side surfaces 3, 17 change. These abutting portions are provided on the outer side in the radial direction of the input side inner side surface 3 and on the output side inner side surface 20.
The gear ratio changes to the speed increasing side as it changes inward in the radial direction. On the other hand, the abutting portions are located radially inward of the input-side inner side surface 3 on the output-side inner side surface 20.
The gear ratio changes to the deceleration side as it changes outward in the radial direction.

By the way, in order to reduce the number of parts and to reduce the size and weight of the toroidal type continuously variable transmission as shown in FIG. 5 described above, Japanese Unexamined Patent Publication No. 11-141637 discloses a structure as shown in FIG. The structure is described. The cutting position of FIG. 1 differs from that of FIG. 5 by 90 degrees in the circumferential direction of the input rotary shaft 1. The toroidal type continuously variable transmission as shown in FIG.
An intermediate disk 30 around the circumference of the pair of needle bearings 2
7 and 27 support relative rotation with respect to the input rotary shaft 1 and axial displacement freely.

The intermediate disc 30 is a combination (integrally formed) of a pair of output side discs 16a and 16b (see FIG. 5), and a gear described in the claims on the outer peripheral surface of the intermediate disc 30. Output gear 15a corresponding to
Formed directly. In the case of such a structure, the rotational force can be transmitted between the pair of input side disks 2a and 2b by the one intermediate disk 30 which functions as the pair of output side disks. Therefore, the axial length of the input rotary shaft 1 can be shortened by reducing the axial dimension of the portion where the intermediate disk 30 is installed, and the output cylinder 28, the pair of rolling bearings 14 and 14, the partition wall 12 (FIG. 5). As a result, the size and weight of the toroidal type continuously variable transmission can be reduced by reducing the number of parts and the axial dimension.

[0016]

In the case of the toroidal type continuously variable transmission which is the object of the present invention as shown in FIG. 1 described above, the intermediate disc 30 is formed by integrally forming a pair of output side discs. There is a demand for technology that can improve durability. That is, in the case of the output side disks 16a and 16b, the intermediate disk 30 is such that only the inner side surface 17, which is one side surface in the axial direction, contacts the peripheral surfaces 29 and 29 of the power rollers 19 and 19 as shown in FIG. Different from the axial sides 3
1 and 31 are the peripheral surfaces 29 of the power rollers 19 and 19,
It is in contact with 29. In such an abutting portion (traction portion), power (torque) is transmitted while a large pressing force based on the thrust of the pressing device 6 is applied during operation.

In this way, the axially opposite side surfaces 31, 3 of the intermediate disk 30 to which a large pressing force and torque are applied are applied.
In order to secure the durability of No. 1, it is considered to perform carburizing quench treatment, carbonitriding quench treatment or the like on each of the side surfaces 31, 31. That is, by performing such a surface hardening treatment, both axial side surfaces 31, 3 of the intermediate disk 30 are
It is considered that a hardened layer (carburized layer, carbonitrided layer) is formed on No. 1 to secure the hardness (surface hardness) of each of the side surfaces 31, 31. However, even if the hardness (of the surface) of each of the side surfaces 31, 31 can be secured in this way, in the case of the intermediate disk 30 to which a large pressing force and torque are applied to each of the side surfaces 31, 31 as described above, This intermediate disc 3
0 where the above-mentioned hardened layer is not formed (each side surface 3
A large shear stress is applied even in a portion deep from 1 and 31 in the axial direction).

That is, as shown in FIG. 2, in the axial cross section of the intermediate disk 30, the shearing stress applied between A and B in FIG. 2 is as shown in FIG. In addition to becoming larger in the vicinity of each of the side surfaces 31, 31, the shear stress is also added to become larger at the central portion in the axial direction of the intermediate disk 30 as shown by the chain line in FIG. As a result, the intermediate disk 30 may reach the end of its life in a short period of time due to the shear stress applied to the central portion of the intermediate disk 30 in the axial direction. In particular, in order to further reduce the size and weight of the toroidal type continuously variable transmission, it is required to further reduce the axial dimension of the intermediate disc 30 (the intermediate disc 30 is thin) as described above. Even in such a case, it is preferable that the durability of the intermediate disk 30 can be secured. The toroidal type continuously variable transmission of the present invention was invented in view of such circumstances.

[0019]

A toroidal type continuously variable transmission according to the present invention includes a rotating shaft, a pair of outer disks, an intermediate disk, a gear, and a power roller. Each of the outer discs is supported at both ends of the rotary shaft so as to freely rotate in synchronism with the rotary shaft in a state where the inner side faces, which are concave surfaces having an arcuate cross section, face each other.
The intermediate disk has axially opposite side surfaces each having a concave surface with an arcuate cross section, and is supported around the rotary shaft so as to be rotatable relative to the rotary shaft. The gear is concentric with the rotary shaft and is directly formed on the outer peripheral surface of the intermediate disk. Further, a plurality of the power rollers are provided between both side surfaces of the intermediate disk in the axial direction and the inner side surfaces of the outer disks. Particularly, in the toroidal type continuously variable transmission of the present invention, the intermediate disk is made of carbon steel containing 0.3 to 0.5% by weight of carbon (C). As such carbon steel, medium carbon steel and some chromium molybdenum steel can be used.

[0020]

In the case of the toroidal type continuously variable transmission of the present invention constructed as described above, the durability of the intermediate disk can be improved. That is, carbon (C) of 0.3-
Since it is made of carbon steel containing 0.5% by weight, a hardened layer is not formed even if surface hardening treatment such as carburizing quenching or carbonitriding quenching is performed (carbon is not added). Also contains sufficient carbon. Therefore, it is possible to sufficiently secure the hardness of the portion where the hardened layer is not formed in the central portion in the axial direction of the intermediate disk. As a result, it is possible to sufficiently secure the durability of the intermediate disk in which a large shear stress is applied to this portion. Furthermore, even when the axial dimension of the intermediate disc is made smaller (the intermediate disc is made thinner), the durability of the intermediate disc can be ensured. If the amount of carbon is less than 0.3% by weight, oxide-based non-metallic inclusions increase due to an increase in the amount of oxygen contained in steel, and sufficient durability may not be ensured. There is. On the other hand, when the amount of carbon exceeds 0.5% by weight, the fatigue crack growth rate (the rate from the initiation of cracking to the initiation of cracking) increases, and sufficient toughness may not be ensured. .

[0021]

1 and 2 show an example of an embodiment of the present invention. The feature of the present invention is that by devising the composition of the metal material forming the intermediate disk 30 in which the pair of output disks 16a and 16b (see FIG. 5) are integrated (integrated), This is to improve the durability of this intermediate disk. Since the structure and operation of the other parts are similar to those of the conventional structure shown in FIG. 5, the same parts are designated by the same reference numerals to omit or simplify the overlapping description. The part will be mainly described. The cutting positions in FIGS. 1 and 5 differ by 90 degrees in the circumferential direction of the input rotary shaft 1.

At both ends of the input rotary shaft 1, a pair of input side disks 2a, 2b are respectively provided with ball splines 4,
It supports through 4. On the other hand, the intermediate disc 30 is supported around the intermediate portion of the input rotary shaft 1 by a pair of needle bearings 27, 27 so as to be rotatable relative to the input rotary shaft 1 and axially displaceable. The intermediate disk 30 is a pair of output disks 16a and 16b.
(See Figure 5)
Then, the output gear 15a corresponding to the gear described in the claims is directly formed on the outer peripheral surface of the intermediate disk 30.

Particularly, in the toroidal type continuously variable transmission of the present invention, the intermediate disk 30 contains carbon (C) of less than 0.
It is made of carbon steel containing 3 to 0.5% by weight. Examples of such carbon steel include medium carbon steel and some chromium-molybdenum steels (SCM430, SCM435, SCM4).
40, SCM445) and the like can be used. In addition, in both axial side surfaces 31 and 31 of the intermediate disk 30 that come into contact with the peripheral surfaces 29 and 29 (see FIG. 5) of the power rollers 19 and 19, the surfaces subjected to carburizing quenching treatment, carbonitriding quenching treatment, and the like. The cured layer is formed by the curing treatment. As such a surface hardening treatment, for example, JP-A-2001-82
It is preferable to carry out under the conditions disclosed in Japanese Patent Publication No. 566. Further, the hardness (hardness of the core) of a portion where the hardened layer is not formed in the central portion of the intermediate disk 30 in the axial direction is Vickers hardness (Hv), and the shear stress value τ [kgf / Mm ² ], which is more than 6 times (Hv> 6τ).

In the case of the toroidal type continuously variable transmission of the present invention configured as described above, the durability of the intermediate disk 30 can be improved. That is, since the intermediate disk 30 is made of carbon steel (medium carbon steel or some chromium molybdenum steel) containing 0.3 to 0.5% by weight of carbon (C), carburizing quenching treatment or carbonitriding quenching treatment is performed. A hardened layer is not formed even if a surface hardening treatment such as the above is performed (carbon or the like is not added), and sufficient carbon is contained also in the axial center portion (core portion) of the intermediate disk 30. Therefore, it is possible to sufficiently secure the hardness of the portion where the hardened layer is not formed in the central portion of the intermediate disk 30 in the axial direction.

That is, the hardness of the carbon steel of the present example (medium carbon steel) is as shown by the solid line in FIG. 4, as compared with the carburized steel containing 0.3% by weight or less of carbon, which is shown by the chain line in FIG. , Axial side 3
Sufficient hardness can be secured even from 1 to 31 deep. As a result, it is possible to sufficiently secure the durability of the intermediate disk 30 in which a large shear stress is applied to this portion. Furthermore, even when the axial dimension of the intermediate disc 30 is further reduced (the intermediate disc 30 is made thinner), the durability of the intermediate disc 30 can be ensured.

If the amount of carbon is less than 0.3% by weight, oxide-based nonmetallic inclusions increase due to an increase in the amount of oxygen contained in steel, and sufficient durability can be secured. It may disappear. On the other hand, when the amount of carbon exceeds 0.5% by weight, the fatigue crack growth rate (the rate from the initiation of cracking to the initiation of cracking) increases, and sufficient toughness may not be ensured. .

In this example, the structure in which the intermediate disk 30 is used as the output side disk is shown. However, the structure is not limited to such a structure, and the intermediate disk is used as the input side disk and a pair of outsides. The disc may be the output disc.

[0028]

Since the present invention is constructed and operates as described above, it is possible to realize a toroidal type continuously variable transmission which is compact and lightweight and has excellent durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part showing a structure to which the present invention is applied.

FIG. 2 is an enlarged view of a portion A of FIG. 1 with a part thereof omitted.

FIG. 3 is a graph showing the magnitude of shear stress in the axial section of the intermediate disc.

FIG. 4 is a graph showing the relationship between the depth from the side surface of the intermediate disk and the hardness at this depth.

FIG. 5 is a cross-sectional view showing a part of a basic configuration of a toroidal type continuously variable transmission that has been widely known from the past, regarding a portion where the phase in the circumferential direction differs from that in FIG.

[Explanation of symbols]

1 input rotation axis 2a, 2b Input side disc 3 Input side inner surface 4 ball spline 5 Rolling bearing 6 Pressing device 7 cam plate 8 drive shafts 9 loading nut 10 Disc leaf spring 11 casing 12 partition 13 through holes 14 Rolling bearing 15,15a Output gear 16a, 16b Output side disc 17 Output side inner surface 18 Needle bearing 19 Power roller 20 trunnion 21 Displacement axis 22 Radial needle bearing 23 Thrust ball bearings 24 Thrust needle bearing 25a, 25b Support plate 26 Preload spring 27 Needle bearing 28 Output tube 29 circumference 30 intermediate disc 31 side

Claims (2)

[Claims] 1. A rotary shaft and an inner surface, which is a concave surface having an arcuate cross section, are opposed to each other, and both ends of the rotary shaft are rotatably supported in synchronization with the rotary shaft.
A pair of outer discs and axially opposite side faces are formed into concave faces having an arcuate cross section, and an intermediate disc that is supported around the rotating shaft so as to be rotatable relative to the rotating shaft is formed directly on the outer peripheral face of the intermediate disc. A toroidal type continuously variable transmission including gears concentric with the rotary shaft, and a plurality of power rollers provided between the axially opposite side surfaces of the intermediate disk and the inner side surfaces of the outer disks. Where 0.3 to 0.5% by weight of carbon is added to the intermediate disk.
A toroidal type continuously variable transmission characterized by being made of carbon steel including. 2. The intermediate disk is an output disk,
The toroidal type continuously variable transmission according to claim 1, wherein the gear is an output gear.