Friction Ring Transmission Adjustment Mechanism for Electric Bicycles
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Solution Overview
Problem
Friction ring transmissions in vehicles, such as electric bicycles, face inefficiencies due to friction processes and heavy force feedback devices, and have limited design freedom in adjusting transmission ratios, which complicates integration and increases weight.
Innovation Solution
A friction ring transmission with an adjustable device that moves along a path less than 180 degrees, integrated into a housing, allowing for a lightweight and compact design with a force return device inside the friction rings, eliminating the need for adjustment threads and enabling easy translation of the transmission ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the force feedback device runs around the outside of the friction ring transmission, then the force feedback device can transmit contact pressure between friction rings, but the force feedback device becomes heavy and large in surface area
Solution Approach 1:
The force feedback device is arranged inside the friction ring transmission, specifically within the space between the inner friction ring and outer friction ring. This nested arrangement allows the force feedback device to transmit contact pressure while being contained within the existing transmission structure, eliminating the need for external heavy components.
2Ease of operation
If transmission ratio adjustment is done through the interior of input or output shaft using threads, then adjustment is achieved, but design freedom is significantly impeded and rotary movement of a few turns is required
Solution Approach 1:
The adjustment mechanism is extracted from the traditional threaded interior shaft design and repositioned to the exterior of the housing. This allows the adjustment device to be operated from outside the transmission assembly, eliminating complex internal threading and reducing the number of rotational turns required for adjustment.
Solution Approach 2:
The adjustment mechanism transitions from a rotational adjustment through threaded shafts to a linear or radial adjustment through the housing wall. This dimensional change from internal rotational adjustment to external linear/radial adjustment simplifies the mechanism and improves design freedom.
3Stability of the object's composition
If the adjustment axis of rotation is fixed and runs coaxially to the central axis of the gear, then the adjustment mechanism is stable, but design freedom for integrating the transmission into a vehicle is significantly impeded
Solution Approach 1:
The adjustment mechanism transitions from a fixed coaxial rotational axis to a movable adjustment device that can be positioned at different locations on the housing. This dynamic repositioning capability allows the transmission to be integrated into various vehicle configurations while maintaining stable adjustment functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances efficiency, reduces weight, and simplifies adjustment, achieving optimal mass distribution and improved handling by allowing the crankshaft to be centered, resulting in a more integrated and efficient drive system.
Implementation Method 1
at least one rotatable double tapered roller which is in frictional engagement with the inner and outer friction rings. When a torque is transmitted, a pressing force acts in each case between the double tapered roller and the friction rings in order to generate friction.
Data Source
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AI summary
The invention relates to a friction ring-type transmission for a vehicle (100) that is operated using motor power and/or pedal force and comprises a crank axle (9) for crank arms (102, 103), especially for an electric bicycle. The friction ring-type transmission (2) comprises an inner friction ring (26), an outer friction ring (20) and at least one rotatable double-cone roll (23) that is arranged on a roll support (22) and frictionally engages with the inner friction ring (26) and the outer friction ring (20) at a certain contact pressure when torque is transmitted via the friction ring-type transmission (2). A frictional connecting device is arranged in a power flow path from the inner friction ring (26) to the outer friction ring (20) in order to transmit contact pressure from one friction ring (20, 26) to the other friction ring (20, 26). One of the friction rings (20, 26) is rotationally fixed in relation to the frictional connecting device, while the other friction ring (20, 26) is rotatable in relation to the frictional connecting device. The friction ring-type transmission (2) further comprises an adjustment device (12) for adjusting the transmission ratio, said adjustment device (12) being movable along an adjustment path extending in the direction of a central axis (M) of the friction rings (20, 26). Furthermore, the adjustment device (12) extends less than 360 degrees about a central axis (M) of the roll support (22).