Infinite speed ratio transmission device

Details Infinite speed ratio transmission device Infinite speed ratio transmission device

2000-01-27

2001-10-23

Estremsky, Sherry (Department: 3681)

Planetary gear transmission systems or components

Nonplanetary variable speed or direction transmission...

Nonplanetary transmission is friction gearing

C475S216000, C476S041000, C074S410000

Reexamination Certificate

active

06306059

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to helical gears used for an 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 infinite speed ratio transmission devices 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 each of these devices, an engine output is input into the CVT and the fixed speed ratio transmission. The output shaft of the CVT is joined with a sun gear of the planetary gear set, and the output shaft of the fixed speed ratio transmission is joined with a planet carrier of the planetary gear set via a power circulation clutch. A ring gear of the planetary gear set joined to a final output shaft of the transmission device drives the wheels. The output shaft of the 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, helical gears are generally used. Some of these helical gears are fixed to the final output shaft. The helical gears generate a thrust load in a gripping part according to the tooth trace direction of the gears 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, comprising an input disk, a final output shaft, a planetary gear set, a continuously variable transmission, a fixed speed ratio transmission, a device output gear fixed to the final output shaft, and a final gear engaging with the device output gear.
The planetary gear set comprises a planet gear, a planet carrier supporting the planet gear, a sun gear externally connected to the planet gear, and a ring gear internally connected to the planet gear. The ring gear is joined to the final output shaft. The continuously variable transmission transmits a rotation of the input shaft to the sun gear at an arbitrary speed ratio. The fixed speed ratio transmission comprises an input gear fixed to the input shaft, and an output gear which is engaged with the input gear, fixed to the planet carrier and rotating around the final output shaft.
The input gear, the output gear, the device output gear, the final gear, the sun gear, the planet gear and the ring gear all comprise helical gears having oblique tooth traces.
The directions of the tooth traces of the sun gear, planet gear and ring gear are set so that a thrust load exerted by the planet carrier, which rotates faster than the sun gear, on the sun gear via the planet gear, and a thrust load exerted by the planet carrier, which rotates faster than the sun gear, on the ring gear via the planet gear, do not cancel each other out. A member is further provided which supports a load acting on the sun gear along the final output shaft. The directions of the tooth traces of the output gear, the input gear, the device output gear and the final gear are set so that either of the thrust load acting on the device output gear and the thrust load acting on the output gear is opposite to the thrust load acting on the ring gear.
Alternatively, the directions of the tooth traces of the sun gear, planet gear and ring gear are set so that a thrust load exerted by the planet carrier, which rotates faster than the sun gear, on the sun gear via the planet gear, and a thrust load exerted by the planet carrier, which rotates faster than the sun gear, on the ring gear via the planet gear, cancel each other out. In this case, the directions of the tooth traces of the fixed output gear, the fixed input gear, the device output gear and the final gear are set so that the thrust load acting on the device output gear and the thrust load acting on the output gear act on the final output shaft in opposite directions.
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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