Infinite speed ratio transmission device

Details Infinite speed ratio transmission device Infinite speed ratio transmission device

2000-03-09

2001-09-04

Estremsky, Sherry (Department: 3681)

Planetary gear transmission systems or components

Nonplanetary variable speed or direction transmission...

Nonplanetary transmission is friction gearing

C475S217000, C074S60600R

Reexamination Certificate

active

06283888

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the structure of an infinite speed ratio transmission device for vehicles using a toroidal continuously variable transmission.
BACKGROUND OF THE INVENTION
Tokkai Sho 63-219956 published by the Japanese Patent Office in 1988 discloses an infinite speed ratio transmission device for vehicles using a toroidal continuously variable transmission (CVT).
In this transmission device, a CVT having a speed ratio which can be continuously varied, and a fixed speed ratio transmission, are connected in parallel to an input shaft joined to an engine, the rotation of the output shafts of the transmissions are input to a planetary gear set, and the final output rotation from the planetary gear set is extracted as a drive torque of the vehicle.
The rotation output of the CVT is input to a sun gear of the planetary gear set via a chain and a sprocket, and the output shaft of the fixed speed ratio transmission is joined to a planet carrier of the planetary gear set via a power circulation mode clutch.
A ring gear of the planetary gear mechanism is joined to a final output shaft.
The rotation output of the CVT is also input to the final output shaft via a direct connection mode clutch.
In a power circulation mode wherein a power circulation mode clutch is engaged and a direct mode clutch is disengaged, a speed ratio of the infinite speed ratio transmission device, i.e., the ratio of the rotation speeds of the input shaft and final output shaft, can be continuously varied from a negative value to a positive value including infinity according to the difference of the speed ratio of the CVT and the speed ratio of the fixed speed ratio transmission.
In a direct mode wherein the power circulation mode clutch is disengaged and the direct mode clutch is engaged, the product of the speed ratio of the CVT and a speed ratio due to chain transmission is the speed ratio of the infinite speed ratio continuously variable transmission.
Tokkai Hei 9-317837 published by the Japanese Patent Office in 1997 discloses a CVT having two sets of toroidal units and an intermediate wall which is provided between the toroidal units and support output disks via bearings. The intermediate wall comprises a pair of partitions which are fixed to brackets projecting inwards from a casing of the CVT by bolts.
SUMMARY OF THE INVENTION
Tokkai Hei 9-317837 disposes the bolts in parallel with an input shaft of the CVT. If this CVT is applied to an infinite speed ratio transmission device, one possible arrangement is that an output sprocket is provided instead of the output gear between the partitions, and the rotation of the output sprocket is transmitted to the sun gear of the planetary gear set via a chain.
If this arrangement is applied, the tension of the chain exerts a force on the output sprocket which is perpendicular to the input shaft. This force is supported by the partitions via the bearings and, as a result, a shearing force acts on the bolts which fix the partitions to the casing.
This means that the size and number of bolts must be increased according to the tension of the chain.
Considering the assembling process of the transmission device, the final output shaft on which a sprocket with the chain looped around, is first inserted into the casing. One of the partitions and the output sprocket is then put into the casing, and after looping the chain around the output sprocket, the other partition is put into the casing and the partitions are fixed together to the casing by means of the bolts. The assembling of the partitions and the fixing thereof to the casing are performed from an opening corresponding to an axial end of the casing. Before securing the bolts, the partitions must be positioned so that the bolt holes of the partitions and those of the bracket of the casing coincide with each other. However, since the partitions are situated effectively in the middle of the casing, it is difficult to precisely position the partitions from the opening at the axial end of the casing. Screwing of the bolts into the bolt holes is also performed from this opening. In order to perform this operation, it is necessary to insert a tool into a narrow space in casing from the opening.
However, if the opening of the casing is enlarged in order to facilitate the positioning of partitions and tightening of the bolts, the rigidity of the whole casing declines and it is difficult to reserve space for installing auxiliary devices, such as an oil pump, which are fitted to the outside of the casing.
It is therefore an object of this invention to support the tension of a chain without depending on the shearing resistance of bolts.
It is another object of this invention to facilitate the fixing of partitions to the casing.
It is yet another object of this invention to facilitate the assembly of an infinite speed ratio transmission device, without reducing the rigidity of the casing.
In order to achieve the above objects, this invention provides an infinite speed ratio transmission device for a vehicle, comprising an input shaft, a first toroidal unit, a second toroidal unit, a first sprocket, a fixed speed ratio transmission, a planetary gear set, a chain, a casing and an intermediate wall.
The first toroidal unit includes a first input disk which rotates together with the input shaft, a first output disk, and two power rollers gripped between the first input disk and the first output disk. The second toroidal unit includes a second input disk which rotates together with the input shaft, a second output disk, and two power rollers gripped between the second input disk and the second output disk, the first and second output disks being disposed coaxially adjacent to each other. The first sprocket is disposed between the first and second output disks, and rotates together with the first and second output disks.
The fixed speed ratio transmission varies the rotation speed of the input shaft at a fixed speed ratio.
The planetary gear set comprises a sun gear joined to a second sprocket, a planet carrier which inputs the output rotation of the fixed speed ratio transmission, and a ring gear which rotates according to the relative rotation of the sun gear and the planet carrier.
The chain connects the first sprocket and the second sprocket.
The casing houses the first toroidal unit, the second toroidal unit and the planetary gear set. The intermediate wall is fixed to the casing and supports the first sprocket free to rotate.
The casing comprises a supporting surface which supports the intermediate wall and forms an approximate right angle to an action direction of a tension of the chain.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.


REFERENCES:
patent: 4872371 (1989-10-01), Fellows
patent: 5902208 (1999-05-01), Nakano
patent: 5935039 (1999-08-01), Sakai et al.
patent: 5976049 (1999-11-01), Yashida et al.
patent: 6171210 (2001-01-01), Miyata et al.
patent: 2274315 (1994-07-01), None
patent: 63-219956 (1988-09-01), None
patent: 9-317837 (1997-12-01), None

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