Friction gear transmission systems or components – Friction transmission or element – Roller bearing between gear and support
Reexamination Certificate
2000-09-22
2001-10-02
Wright, Dirk (Department: 3681)
Friction gear transmission systems or components
Friction transmission or element
Roller bearing between gear and support
Reexamination Certificate
active
06296591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving apparatus of a so-called traction type or friction drive type, wherein torque transmission is realized with low noise and low vibration by utilizing shearing resistance of oil membrane or frictional resistance (when lubricant is not used) between cylindrical surfaces pressed to each other. The present invention relates to improvement of a driving apparatus of such a type.
2. Description of Related Art
Traction drive type driving apparatus has been known as a low noise driving apparatus. Conventionally, as a transmitting apparatus of such a type, for example, Japanese Patent Publication No. Sho 62-46742 discloses a driving force transmitting apparatus of a planetary roller type provided with an elastic roller. The transmitting apparatus disclosed in the Japanese Patent Publication No. Sho 62-46742, forces are exerted to the elastic roller having U-shaped cross section from both the sides so that the inner diameter of the roller is decreased so as to obtain pressing force.
Japanese Patent Publication No. Sho 51-25538 discloses a reduction device using frictional transmission wherein an input spindle and output spindle are opposed on a same axis, a plurality of rollers are disposed between an inner race integrally formed with the input spindle and a fixed elastically deformable outer race, a shaft with a holding ring for rotatably supporting the rollers is connected to the output spindle, an annular hydraulic chamber is formed between the outer race and a housing of the reduction device, and when frictional transmission is effected from the input spindle to the output spindle via the rollers, hydraulic pressure corresponding to the load of the output spindle is supplied to the hydraulic chamber so as to decrease the outer race in a radial direction, and radial pressure is applied to the rollers.
Problems to be Solved by the Invention
In the transmitting apparatus disclosed in Japanese Patent Publication No. Sho 62-46742, the elastic roller with U-shaped cross section is complicated in its shape, and it is complicated also in its construction since it requires a mechanism for deforming both the sides. Accordingly, it leads to high cost. Further, test for confirming the pressing load at a desired amount is very difficult.
Further, in the elastic roller disposed in the reduction device in the apparatus disclosed in Japanese Patent Publication No. Sho 62-46742, the U-shaped cross section is relatively small, and occurrence of a large stress is inevitable when it is deformed big. In addition to this, the decreasing amount of the inner diameter of the elastic roller cannot be increased when strength against fatigue of the material is took into consideration. Accordingly, it is difficult to obtain a large pressing force, and even when only a little bit initial abrasion occurs, the pressing load is sharply decreased, and accordingly, the transmitting capability is widely decreased and reliability is lowered.
Contrary to this, in the reduction device disclosed in the Japanese Patent Publication No. Sho 51-25538, the hydraulic chamber is formed by the inner roller and the casing by constructing the inner roller, i.e., the outer race in such a manner that inner surface of the thick cylindrical portion is connected to both the ends of the relatively thin cylindrical portion. When the thin cylindrical portion of the inner roller is deformed toward the center by applying working oil into the hydraulic cylinder, pressing force is exerted between the inner roller and the planetary roller.
However, in the reduction device disclosed in the Japanese Patent Publication No. Sho 51-25538, since the inner roller is hydraulically deformed, conduits for introducing hydraulic power and sealing means are required, and accordingly, the device becomes complicated, and inconvenience in decrease of hydraulic pressure due to, for example, leakage of oil may occur easily.
BRIEF SUMMARY OF THE INVENTION
OBJECTS OF THE INVENTION
It is an object of the present invention to obviate the problems inherent to the above-described prior art.
It is another object of the present invention to provide a traction drive type driving apparatus, by which any particular pressing mechanism is unnecessary.
It is a still other object of the present invention to provide a traction drive type driving apparatus, by which a big deformation can be obtained easily.
It is a further object of the present invention to provide a traction drive type driving apparatus, in which decreasing degree of the pressing load is extremely small against small amount of abrasion.
It is a still further object of the present invention to provide a traction drive type driving apparatus, in which the test for confirming the pressing load at a desired amount can be done easily.
It is a further object of the present invention to provide a traction drive type driving apparatus, which has a readily constructible hollow structure.
Means to Solve the Problems
According to the first aspect of the present invention, the objects are achieved by a traction drive type driving apparatus comprising an externally contacting shaft located at the center, a plurality of intermediate shafts equidistantly disposed around and externally contacting with the externally contacting shaft, and an internally contacting cylinder internally contacting with the intermediate shafts, at least one of the intermediate shafts offset from the center being an input shaft, and the externally contacting shaft being a ring-like hollow cylinder.
In this occasion, it is preferred that the externally contacting shaft forming the ring-like hollow cylinder is supported by the intermediate shafts without disposing any particular supporting bearing to form a floating ring, and the hollow externally contacting shaft has an outer diameter under free condition being a little bit larger than the diameter of an imaginary circle which externally contacts with the plurality of intermediate shafts whereby pressing load is created by deformation of the hollow cylinder.
In the traction drive type driving apparatus according to the present invention, the internally contacting cylinder may comprise coaxially arranged double hollow rings, and the inner ring and the outer ring of the double hollow rings may be connected to each other by means of connecting means.
In this case, it is preferred that the inner ring of the internally contacting cylinder of the ring-like hollow cylinder is supported by the intermediate shafts without disposing any particular supporting bearing to form a floating ring, whereby deformation of the inner ring caused by deformation of the externally contacting shaft formed in the ring-like hollow cylinder is prevented from being transmitted to the outer ring.
In the present invention of this type, the internally contacting cylinder may be an output shaft, or it may further comprise a supporting member for rotatably supporting the plurality of intermediate shafts and the internally contacting cylinder, and the supporting member may be an output shaft.
Further, according to another aspect of the present invention, the objects are achieved by a traction drive type driving apparatus comprising an externally contacting shaft located at the center, a plurality of intermediate shafts equidistantly disposed around and externally contacting with the externally contacting shaft, and an internally contacting cylinder internally contacting with the intermediate shafts, the externally contacting shaft or at least one of the intermediate shafts being an input shaft, the internally contacting cylinder being of deformable hollow ring-like and integrally engaging with a holding member of the internally contacting cylinder by means of a holding means.
In this occasion, it is preferred that, the internally contacting cylinder of a ring-like hollow cylinder is supported by the intermediate shafts without disposing any particular supporting bearing to form a floating ring, and the hollow internally contacting cylinder h
Rothwell Figg Ernst & Manbeck
Teijin Seiki Co. Ltd.
Wright Dirk
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