초록 ▼

Continuously variable speed drive (CVT) have improved performance due to use of two groups of flyweight cams, each group being mounted on separate rotational members of a centrifugal clutch. One set of flyweight cams provides force to close the sheaves through the entire movement of the shift, where

Continuously variable speed drive (CVT) have improved performance due to use of two groups of flyweight cams, each group being mounted on separate rotational members of a centrifugal clutch. One set of flyweight cams provides force to close the sheaves through the entire movement of the shift, whereas the other set of flyweight cams provides force only through an initial portion of the shift and then signs off. This provides a two stage shift behavior for the CVT that enhances power transfer to the driven pulley.

대표청구항 ▼

1. A variable ratio centrifugal clutch driving assembly for use in a continuously variable transmission to connect with a driven assembly by means of an endless belt, the clutch driving assembly comprising: a rotatable shaft;a first rotatable member comprising a first sheave mounted on the shaft for

1. A variable ratio centrifugal clutch driving assembly for use in a continuously variable transmission to connect with a driven assembly by means of an endless belt, the clutch driving assembly comprising: a rotatable shaft;a first rotatable member comprising a first sheave mounted on the shaft for rotation therewith and axially stationary thereon;a second rotatable member comprising a second sheave mounted on the shaft for rotation therewith and axially movable relative to the first sheave to variably control the radial position of the endless belt disposed therebetween;a third rotatable member mounted on the shaft for rotation therewith and axially stationary thereon;a first group of plural flyweights pivotally mounted on the second rotatable member and arranged to move radially outward with increasing rotational velocity of the shaft, each flyweight of the first group having formed thereon a first group cam surface to effect predetermined first and second modes of movement of the second sheave with respect to the first sheave, each of said first group cam surfaces being positioned to engage with a corresponding first group cam engaging member disposed on the third rotatable member to effect said first and second modes of movement; anda second group of plural flyweights pivotally mounted on the third rotatable member and arranged to move radially outward with increasing rotational velocity of the shaft, each flyweight of the second group having formed thereon a second group cam surface to effect only the predetermined first mode of movement of the second sheave with respect to the first sheave, each said second group cam surface being positioned to engage with a corresponding second group cam engaging member disposed on the second rotatable member to effect said first mode of movement. 2. The variable ratio centrifugal clutch driving assembly recited in claim 1, wherein the second group of plural flyweights pivot through only a portion of any axial movement of the second sheave relative to the first sheave. 3. The variable ratio centrifugal clutch driving assembly recited in claim 1, wherein the first group of plural flyweights pivot through the entirety of any axial movement of the second sheave relative to the first sheave and wherein the second group of plural flyweights pivot through less than the entirety of any axial movement of the second sheave relative to the first sheave. 4. A variable ratio centrifugal clutch driving assembly for use in a continuously variable transmission to connect with a driven assembly by means of an endless belt, the clutch driving assembly comprising: a rotatable shaft;a first rotatable sheave mounted on said shaft for rotation therewith, said first rotatable sheave being axially stationary on said shaft;a second rotatable sheave mounted on said shaft for rotation therewith, said rotatable sheave being axially movable relative to said first sheave to variably control the radial position of the endless belt disposed therebetween;a third rotatable member disposed on said shaft for rotation therewith;a first set of flyweights being pivotally mounted to said second rotatable sheave, said first set of flyweights each having an axis of rotation with each axis of rotation lying in a first horizontal plane, which is perpendicular to an axis of rotation of said rotatable shaft, each of said first set of flyweights having a cam surface that applies a force on said second rotatable sheave throughout an entire range of movement of said second sheave;a second set of flyweights being pivotally mounted to said third rotatable member, second set of flyweights each having an axis of rotation with each axis of rotation lying in a second horizontal plane, said second horizontal plane being parallel to said first horizontal plane, each of said second set of flyweights having a cam surface that contacts said second rotatable sheave to apply an additional force on said second rotatable sheave throughout a predetermined portion of said range of movement of said second sheave, where said predetermined portion is less than said entire range of movement of said second rotatable sheave;whereby said second set of flyweights are not in engagement with said second rotatable sheave for any portion of said entire range of movement beyond said predetermined portion. 5. The clutch assembly of claim 4, wherein said first set of flyweights are mounted on said second sheave. 6. The clutch assembly of claim 5, wherein said second set of flyweights are mounted on a rotatable spider assembly, which is a separate member from said second sheave. 7. The clutch assembly of claim 6, wherein said cam surfaces of said first set of flyweights engage a respective first roller assembly to effectuate application of said downward force on said second sheave by said first set of flyweights as they pivotally move in response to the varying rotational speed of said rotatable shaft. 8. The clutch assembly of claim 7, wherein said first roller assemblies are disposed on said spider assembly. 9. The clutch assembly of claim 8, wherein said cam surfaces of said second set of flyweights engage a respective second roller assembly to effectuate application of said downward force on said second sheave by said second set of flyweights throughout a predetermined amount of pivotal rotation of said first set of flyweights. 10. The clutch assembly of claim 9, wherein said second roller assemblies are disposed on said second sheave. 11. The clutch assembly of claim 4, wherein said axis of rotation of said first set of flyweights and said second set of flyweights are radially fixed with respect to said axis of rotation of said rotatable shaft. 12. The clutch assembly of claim 4, wherein said predetermined portion of said range of motion is less than an entirety of said range of motion of said second sheave. 13. A variable ratio centrifugal clutch driving assembly for use in a continuously variable transmission to connect with a driven assembly by means of an endless belt, the clutch driving assembly comprising: a rotatable shaft;a first sheave mounted on said shaft for rotation therewith;a second sheave mounted on said shaft for rotation therewith;said first sheave and said second sheave defining a distance therebetween, which distance is variable to control a radial position of the endless belt disposed therebetween;an additional rotatable member mounted on said shaft for rotation therewith;a first plurality of weights pivotally mounted on said second sheave and configured to pivot outwardly with increasing rotational velocity of the shaft, each weight of the first plurality of weights configured to effect predetermined first and second modes of movement of said second sheave with respect to said first sheave, each of said first plurality of weights configured to engage said additional rotatable member to effect said first and second modes of movement; anda second plurality of weights pivotally mounted on said additional rotatable member and configured to move radially outwardly with increasing rotational velocity of said shaft, each weight of said second plurality of weights configured to effect said predetermined first mode of movement of said second sheave with respect to said first sheave through engagement with said second sheave,whereby said first mode of movement is less than a total amount of movement of said second sheave with respect to said first sheave and whereby said first mode of movement and said second mode of movement together define said total amount of movement of said second sheave with respect to said first sheave;whereby said second set of flyweights do not effect said second mode of movement of said second sheave with respect to said first sheave. 14. The variable ratio centrifugal clutch driving assembly of claim 13, wherein said first sheave is axially fixed on said rotatable shaft. 15. The variable ratio centrifugal clutch driving assembly of claim 14, wherein said first plurality of weights are flyweights each having a cam surface that contacts a respective roller on said additional rotatable member. 16. The variable ratio centrifugal clutch driving assembly of claim 14, wherein said second plurality of weights are flyweights each having a cam surface that contacts a respective roller on said second sheave. 17. A variable ratio centrifugal clutch driving assembly for use in a continuously variable transmission to connect with a driven assembly through an endless belt, the clutch driving assembly comprising: a rotatable shaft;a first rotatable sheave mounted on said shaft for rotation therewith, said first rotatable sheave being axially stationary on said shaft;a second rotatable sheave mounted on said shaft for rotation therewith, said rotatable sheave being axially movable relative to said first sheave to variably control the radial position of the endless belt disposed therebetween;an additional rotatable member disposed on said shaft for rotation therewith;a first set of weights being pivotally mounted to said second rotatable sheave, said first set of weights each having a first axis of rotation with each axis of rotation lying in a first horizontal plane, which is perpendicular to an axis of rotation of said rotatable shaft, each of said first set of weights having a cam surface that applies a downward force on said second rotatable sheave throughout an entire range of movement of said second sheave, said first axis of rotation of said weights being radially fixed with respect to said axis of rotation of said shaft;a second set of weights being pivotally mounted to said additional rotatable member, second set of weights each having a second axis of rotation with each axis of rotation lying in a second horizontal plane, said second horizontal plane being parallel to said first horizontal plane, each of said second set of weights applying an additional downward force on said second rotatable sheave throughout a predetermined portion of said range of movement of said second sheave, said second axis of rotation being radially fixed with respect to said axis of rotation of said shaft. 18. The variable ratio centrifugal clutch driving assembly of claim 17, wherein each of said second set of weights includes a surface that contacts said second sheave. 19. The variable ratio centrifugal clutch driving assembly of claim 18, wherein said second group of weights consists of a plurality of flyweights each having a cam surface that contacts a roller on said second sheave. 20. The variable ratio centrifugal clutch driving assembly of claim 17, wherein said predetermined portion of said range of motion is less than an entirety of said range of motion of said second sheave. 21. The variable ratio centrifugal clutch driving assembly of claim 17, further comprising: an additional rotatable member mounted on the shaft for rotation therewith, said additional rotatable member being axially stationary on the shaft. 22. The variable ratio centrifugal clutch driving assembly of claim 21, wherein said first group of weights consists of a plurality of flyweights each having a cam surface that contacts a respective roller on said additional rotational member. 23. A variable ratio centrifugal clutch driving assembly for use in a continuously variable transmission to connect with a driven assembly by means of an endless belt, the clutch driving assembly comprising: a rotatable shaft;a first rotatable sheave mounted on said shaft for rotation therewith, said first rotatable sheave being axially stationary on said shaft;a second rotatable sheave mounted on said shaft for rotation therewith, said rotatable sheave being axially movable relative to said first sheave to variably control the radial position of the endless belt disposed therebetween;an additional rotatable member disposed on said shaft for rotation therewith;a first plurality of weights being pivotally mounted to said second rotatable sheave, said first plurality of weights each having an axis of rotation with each axis of rotation lying in a first horizontal plane, which is perpendicular to an axis of rotation of said rotatable shaft, each of said first plurality of weights applies a force on said second rotatable sheave throughout an entire range of movement of said second sheave;a second plurality of weights being pivotally mounted to said additional rotatable member, second plurality of weights each having an axis of rotation with each axis of rotation lying in a second horizontal plane, said second horizontal plane being parallel to said first horizontal plane, each of said second plurality of weights applies an additional force on said second rotatable sheave throughout a predetermined portion of said range of movement of said second sheave;whereby each of said second plurality of weights does not engage said second sheave in any portion of said range of movement of said second sheave beyond said predetermined portion; andwherein said predetermined portion of said range of movement is less than an entirety of said range of movement of said sheave. 24. The clutch assembly of claim 23, wherein said predetermined portion of said range of movement is between 0% to 75%. 25. The clutch assembly of claim 23, wherein said predetermined portion of said range of movement is about 75%. 26. The variable ratio centrifugal clutch driving assembly of claim 23, wherein each of said second plurality of weights includes a surface that contacts said second sheave. 27. The variable ratio centrifugal clutch driving assembly of claim 23, wherein said second plurality of weights are flyweights each having a cam surface that contacts a respective roller on said second sheave.