Transmission unit with planetary gearing system

Abstract

The invention relates to a transmission unit with a planetary gearing system, optionally for bicycles or for trailer bicycles. The transmission unit, which is developed for driving small rear wheels, contains a planetary gearing system with a ring gear (7) which is connected to the bicycle frame (9), a planet carrier (3b) with planet gears (6a, 6b), and one or two sun gears (10, 11). The transmission unit further contains a rear wheel shaft (12) which is coaxial with respect to the sun gears or a rear wheel shaft which has the aforementioned sun gear, and the transmission unit contains a driving mechanism (3) which is coupled to the planet carrier or a driving mechanism (3) which is designed as a planet carrier (3b). The invention is characterized in that a bearing (35) internally bears the rear wheel shaft (12) with respect to the bicycle frame (9) from a radial perspective and between the seat of the rear wheel (40) and the planetary gearing system from an axial perspective, wherein the planetary gearing system and an upstream gear unit, for example a chain drive (1, 2), lie on the same side of the bicycle frame. Thus, upstream belt drives, short distances between the rear wheel and the bottom bracket, and single-arm suspensions in the bicycle frame can be implemented. The transmission unit provides one or two gear ratios.

Description

technical field [0001] The invention relates to a transmission unit with a planetary gear transmission according to the preamble of claim 1, optionally for a bicycle with small wheels or for a bicycle trailer. Background technique [0002] The chain drive is the most popular bicycle drive. In this case, the driving sprocket connected to the pedal is mainly located outside the bicycle frame when viewed axially, and the driven ring gear supported on the rear wheel shaft is mainly arranged inside the bicycle frame and the bicycle frame when viewed axially. between the rear wheels. [0003] Multi-speed shifting for bicycles is preferably via a chain drive with different sprockets on the pedals and a different ring gear on the rear wheel or by a single-stage chain drive combined with a hub shift in the rear wheel or by both A combination of schemes can be realized. This achieves a total gear ratio of up to 1:4.9 in total (eg SRAM i-motion with chainring combination 48 / 18). Th...

AI Technical Summary

Problems solved by technology

[0012] Solution a. has the disadvantage that due to the different arrangement of the drive sprocket (outside) and driven sprocket (inside) relative to the bicycle frame, the bicycle frame must be guided between the sprockets or through the chain drive

There is thus an additional disadvantage: the achievable overall gear ratios for wheel sizes smaller than 14 inches hardly allow for a suitable spread length

The high rotational speeds generated by the second chain drive require high energy consumption

The resulting disadvantage is that the torque of the driven ring gear first has to be transmitted to the rear wheel axle before it can be received by the planetary carrier on the other side of the bicycle frame

Another disadvantage is that the bending moments acting on the rear axle due to the weight of the cyclist also act on the planet carrier in the disclosed solution and prevent the tooth meshing of the planetary transmission

In addition, only one shift gear of the planetary transmission can be realized when the planetary transmission is arranged on the inner side of the bicycle frame, because since the driven sun gear is arranged as the sun gear supported on the rear wheel From the perspective of the wheels, torque transmission can only be carried out axially to the rear wheels

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