Friction gear transmission systems or components – Stepless ratio change – Intermediate idler between driving and driven gears
Patent
1996-05-29
1998-05-05
Herrmann, Allan D.
Friction gear transmission systems or components
Stepless ratio change
Intermediate idler between driving and driven gears
475214, 476 8, 476 33, F16H 1516, F16H 5704
Patent
active
057466769
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a friction type continuously variable transmission for variably adjusting the rotational speed of a drive shaft such as an impeller of a centrifugal blower, a centrifugal compressor or a radial turbine.
2. Background Art
Unexamined Japanese Utility Model Publication 3-5948 discloses a conventional friction type variable transmission capable of rotating an output shaft at a constant speed in spite of the change of the rotational speed of an input shaft by variably adjusting a shaft for driving a high-speed rotary member such as an impeller.
FIG. 14 shows this transmission. It has an input shaft 2 and an output shaft 3 supported by bearings in a housing 1 at both ends so as to be coaxial with each other. A plurality of double cones 4 are arranged around the output shaft 3. They are rotatably mounted on support shafts 6 fixed to a carrier 5 axially movably mounted on the output shaft 3.
The input shaft 2 has at its inner end an integral input ring 7 kept in contact with one conical surface 4a of each double cone 4. The output shaft 3 carries at its inner end a drive cone 8 that contacts the other conical surface 4b of each double cone 4.
A holder 10 is fixed to an outer ring of a bearing 9 supporting the input shaft 2. A plurality of springs 11 are disposed circumferentially between the holder 10 and the housing 1 to axially pull the input shaft 2 via the bearing 9. As the input shaft 2 is pulled by the springs 11, the double cones 4 and thus the output shaft 3 are also pulled in the same direction. But since the output shaft 3 is fixed to the housing, a force that reacts to the biasing force of the springs 11 is produced, so that the input shaft and the output shaft are subjected to a tensile force that tends to pull them away from each other.
When the input shaft 2 is rotated, its rotation is transmitted through the input ring 7 to the double cones 4, and then through the drive cone 8 to the output shaft 3. An impeller mounted on the output shaft 3 is thus rotated. To change the rotational speed of the output shaft 3, the double cones 4 are moved axially of the output shaft 3 by controlling a carrier moving means 12 for axially moving the carrier 5.
In this way, the rotation of the input shaft 2 is transmitted through the input ring 7 to the double cones 4, which are pressed against the input ring 7 under the force of the springs 11. The rotational speed of the output shaft 3 is determined by the axial position of the double cones 4. Thus, it is important that the carrier 5 supporting the double cones 4 and its inner guide 13 be axially movable with sufficient smoothness.
In this respect, the conventional carrier moving means 12 for axially moving the carrier 5 is a rack-and-pinion mechanism, which cannot prevent the rotation of the carrier 5. Thus, when the input shaft 2 is rotated, the double cones 4 tend to rotate about the center axis of the carrier guide 13 while rotating about their own axes. The rotation of the double cones 4 about the carrier guide 13 may have detrimental effects, such as an abrupt change in the speed ratio or the separation of the joint between the carrier moving means 12 and the carrier 5.
If the carrier 5 moves axially out of the permissible range, the double cones 4 will disengage from the drive cone 8 or the input ring 7, making the transmission of torque impossible.
If the input shaft is rotated at a high speed, the double cones 4, rotatably mounted on the support shafts 6 protruding from the carrier 5, are rotated at a correspondingly high speed, so that they may come off of the support shafts 6 because of their own inertia and consequently disengage from the drive cone 8 and the input ring 7.
In this arrangement, whenever the input shaft 2 is rotating, its rotation is transmitted through the integral input ring 7 to the double cones 4 because the input ring 7 is always pressed against the double cones 4 under the force of the springs 11. The double cones 4 are kept rotating and thus the output shaft 3
REFERENCES:
patent: 2886986 (1959-05-01), Kopp
patent: 3420122 (1969-01-01), Okabe
patent: 3598740 (1971-08-01), Duling et al.
patent: 5334097 (1994-08-01), Tatara et al.
Hattori Naoshi
Kawase Tatsuo
Makino Tomoaki
Nozaki Takashi
Saito Takahide
Herrmann Allan D.
NTN Corporation
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