Machine element or mechanism – Mechanical movements – Rotary to rotary
Patent
1999-06-22
2000-12-12
Ta, Khoi Q.
Machine element or mechanism
Mechanical movements
Rotary to rotary
474 70, 474 80, B62M 2502
Patent
active
061582948
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an automatic transmission for bicycle. More particularly, it relates to an automatic transmission for bicycle which is capable of changing a bicycle speed by using the speed of its turning wheels without extra manipulation.
BACKGROUND ART
Nowadays, most bicycles are equipped with a transmission system, and this transmission system makes it more convenient to ride the bicycle when a rider climbs a steep hill or drives the bicycle at a high speed. However, the conventional transmission system has a shift lever that is positioned on either one side of a bicycle steering bar's handle or one side of the bicycle frame. To change the bicycle speed, the rider has to select a gearshift during steering. Therefore, it is inconvenient to frequently change the driven gears to obtain the desired bicycle speed. If the rider puts the shift lever on an inappropriate position, an incorrect gear engagement takes place between the bicycle chain and the chain sprocket, which causes loud noise, abnormal wear and tear between gear sets, etc. In addition, the shift may distract a bicycle beginner from cycling, thereby causing a collision.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic transmission for bicycle which changes a bicycle speed in response to the speed of its turning wheels without extra manipulation.
In order to achieve the above object, the present invention discloses an automatic transmission for bicycle including a support shaft with an interior created by a hollow shaft having a long hole drilled thereinto, and fixed grooves formed on its outer surface at regular intervals; a movable casing mounted on the support shaft; a fixation ball attached to the inside of the movable casing to mate with the fixed grooves of the support shaft; a pin inserted into the movable casing to pass through the support shaft's long hole; a speed-change wire connected to the pin; a coil spring loaded between one side of the movable casing and a clamping bolt; a plurality of rotary balls seated in an outer groove of the movable casing to slightly protrude from the outer groove so that the rotary balls rotate along a thread bottom formed on an inner surface of a revolving body; a plurality of needle bearings provided to an outer surface of the revolving body; a friction band provided to the outside of the needle bearings, and having one side fixed to a rotating axle; and outside of the rotating axle through an outlet. A speed-change device is provided to the inside of the movable casing to fit in a given point of the fixed grooves.
BRIEF DESCRIPTION OF DRAWINGS
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
FIG. 1 is an enlarged sectional view of the present invention as taken from the rear;
FIG. 2 depicts the operating state of a first preferred embodiment of the present invention;
FIG. 3 is a perspective view of a friction band of the present invention;
FIG. 4 depicts a movable casing in accordance with a second preferred embodiment of the present invention;
FIG. 5 is a longitudinal sectional view of the present invention; and
FIG. 6 depicts the operating state of the friction band of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will now be more fully described with reference to the accompanying drawings.
A support shaft 1 with an interior created by a hollow shaft 1a has a long hole 101 drilled thereinto, fixed grooves 102 formed on its outer surface at regular intervals, and a movable casing 2 mounted thereon. A fixation ball 201 is attached to the inside of movable casing 2 to mate with fixed grooves 102 of support shaft 1. A pin 103 is inserted into movable casing 2 to pass through support shaft 1's long hole 101. A speed-change wire 106 is connected to pin 103, and a coil spring 105 is loaded
REFERENCES:
patent: 3830521 (1974-08-01), Gardel et al.
patent: 3948112 (1976-04-01), Gilbert
patent: 4571219 (1986-02-01), Breden et al.
patent: 4713042 (1987-12-01), Imhoff
patent: 5163881 (1992-11-01), Chattin
patent: 5295916 (1994-03-01), Chattin
patent: 6007441 (1999-12-01), Tysver
patent: 6010425 (2000-01-01), Tabe
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