Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural drive ratios other than unity
Patent
1996-08-29
1999-11-02
Ta, Khoi Q.
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural drive ratios other than unity
475338, 280238, B62K 1944, B62M 1106
Patent
active
059760524
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is related to a compact automatic gear change device for a bicycle in which a first set of sprocket wheels (1) mesh with a second set of sprocket wheels (2) by means of an intermediate moving element (3), and are equipped with anti-reverse pawls automatically controlled by mechanical or electronic tachometers.
French Patent No. 2.711.351, published on Apr. 28, 1995, describes a differential selection gear change for a bicycle, based on the difference in the angular speed of the pinions, and on the utilization of anti-reverse pawls, each controlled pawl having a lug added to enable their deactivation to be controlled. The sprocket wheels are free on their axles and mesh constantly by means of an intermediate moving element. Due to the anti-reverse pawls, the sprocket wheels only rotate in one direction and cause the engagement of the highest ratios in a natural fashion by the difference in the angular speed of the sprocket wheels. The speed selection is done by lifting the pawls by means of their lug. Since very little force is necessary to lift a pawl, this device is particularly adapted to the embodiment of a fully automatic gearbox for a bicycle due to mechanical or electronic tachometers measuring the speed of the moving elements and the transmitted torque.
SUMMARY OF THE INVENTION
The object of the present invention is a device that is to provide a gear selection device that is more compact and better integrated into the bicycle. In its general form, the object invention is gear change device for pedal vehicles, and more particularly for a bicycle, in which all of the sprocket wheels providing the gear ratios mesh by means of an intermediate moving element, are freely mounted on their axle and equipped with anti-reverse pawls acting on the other wheel sides shaped like starting teeth, the pawls being equipped with a lug by means of which they are maintained outside of the path of the starting teeth. Their deactivation is obtained by the fully automatic control of a compensated mechanical tachometer or of an electronic tachometer.
A first embodiment of the invention is a line gear cluster incorporated in a sealed housing and connecting the bottom bracket spindle to the wheel spindle by completely eliminating the drive chain. A second embodiment of the invention is composed of coaxial sprocket wheels driven by three intermediate moving elements (3) positioned on the inside of the sprocket wheels, whereas the starting teeth of the first and second sets of sprocket wheels (1) and (2), the controlled and normal pawls (4) and (5) and the tachometers are placed on the outside of the sprocket wheels. The assembly is housed in two sealed housings (44) and (46) that rotate with respect to one another. This compact cylindrical device can be positioned on the wheel or on the bottom bracket and driven by a drive chain.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be illustrated by some of its preferred embodiments, with reference to the annexed drawings, and in which:
FIG. 1 shows a front view of a first embodiment of an automatic gear change device mounted between the axle of the pedal and the axle of the rear wheel of the bicycle;
FIG. 2 shows a cross sectional top view of a second embodiment of the automatic gear change device arranged in a sealed housing, coaxial to the axle of the rear wheel of the bicycle;
FIG. 3 shows a front view of the device of FIG. 2;
FIG. 4 shows the location of the components of the electronic tachometer that controls the embodiment shown in FIG. 2;
FIG. 5 is another similar, but simplified embodiment of the device of FIG. 2;
FIG. 6a shows a closed mechanical tachometer; and
FIG. 6b shows an open mechanical tachometer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Line Gearbox with Flat Housing
In this first embodiment (version), the drive chain has been completely eliminated, and the gears have been arranged on five parallel and in-line axles (I-V, FIG. 1), the first being the bottom bracket spindle and the fif
REFERENCES:
patent: 5099712 (1992-03-01), Douglass
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