Infinite speed ratio transmission device

Details Infinite speed ratio transmission device Infinite speed ratio transmission device

2000-01-27

2001-10-16

Estremsky, Sherry (Department: 3681)

Planetary gear transmission systems or components

Nonplanetary variable speed or direction transmission...

Nonplanetary transmission is friction gearing

C475S216000, C476S010000, C476S042000

Reexamination Certificate

active

06302819

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to helical gears used for infinite speed ratio transmission device for vehicles.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,935,039 and Tokkai Hei 10-220551 published by the Japanese Patent Office in 1998 disclose an infinite speed ratio transmission device for a vehicle wherein a fixed speed ratio transmission and a planetary gear set are combined with a toroidal continuously variable transmission (CVT) in order to increase the speed ratio range of the CVT. In this device, an engine output is input into the CVT and the fixed speed ratio transmission.
The output shaft of the CVT is combined with a sun gear of the planetary gear set, and the output shaft of the fixed speed ratio transmission is combined with a planet carrier of the planetary gear set via a power circulation clutch.
A ring gear of the planetary gear set is joined to a final output shaft of the transmission device which drives the wheels. The output shaft of CVT is also joined to the final output shaft of the transmission via a direct clutch.
SUMMARY OF THE INVENTION
In order to prevent noise and mechanical vibration in the fixed speed ratio transmission and the transmission device output gear of such a transmission device, a helical gear is generally used. Some of these helical gears are fixed to the final output shaft. The helical gears generate a thrust force in a gripping part according to the direction of the helix, and the direction of torque transmission.
On the other hand, when the CVT and sun gear are joined together via a chain, the tension of the chain exerts a force in a perpendicular direction to the final output shaft of the transmission device.
Due to the thrust forces acting on the helical gears, and the perpendicular force exerted by the chain, the final output shaft tends to bend. If the final output shaft bends, the durability of the bearing which supports the final output shaft will decrease, and the power transmission efficiency will fall due to the increase of friction in the bearing.
It is therefore an object of this invention to alleviate the bending of the final output shaft of an infinite speed ratio transmission device.
In order to achieve the above object, this invention provides an infinite speed ratio transmission device for a vehicle, The device comprises an input shaft, a final output shaft, a continuously variable transmission having a first sprocket and transmitting a rotation of the input shaft to the first sprocket at an arbitrary speed ratio, a fixed speed ratio transmission comprising an output gear formed on the final output shaft and an input gear which inputs the rotation of the input shaft and which is meshed with the output gear, a second sprocket formed on the final output shaft, a chain which transmits the rotation of the first sprocket to the second sprocket, a device output gear formed on the final output shaft, a final gear meshed with the device output gear, and a planetary gear set which causes the final output gear to rotate according to the relative rotation of the second sprocket and the output gear.
Either one of a gear set of the input gear and the output gear, or a gear set of the device output gear and the final gear, comprises helical gears having a slanting tooth trace, which, when rotating, exerts a moment on the final output shaft in a direction to suppress a bending stress in the final output shaft due to 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.


REFERENCES:
patent: 5807203 (1998-09-01), Imanishi et al.
patent: 5935039 (1999-08-01), Sakai et al.
patent: 10-220551 (1998-08-01), None

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