Bicycle Brake Actuator Loop Tensioning Mechanism
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Solution Overview
Problem
Existing electric bicycles with mid-motor designs cannot be equipped with coaster brakes due to design complexities and space constraints, despite the advantages of coaster brakes in terms of comfort and intuitive use.
Innovation Solution
A brake actuator system comprising a loop attached to a lever element on the pedal drive shaft, which tensions during backpedaling to transmit the motion to a mechanical brake connection, allowing for coaster braking without the need for a gear hub, utilizing a loop with high tensile strength and a lever element with a pivot bearing to manage tension and frictional contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a coaster brake system is implemented on electric bicycles with mid-motor designs, then the braking comfort and intuitiveness are improved, but the device complexity and space requirements increase
Solution Approach 1:
The brake actuator is integrated directly into the pedal drive shaft assembly, merging the braking function with the existing drive mechanism. The loop is attached to the pedal drive shaft and the lever element is mounted on the same shaft, combining two functions into one compact unit without requiring separate brake housing or additional complex mechanisms
Solution Approach 2:
The pedal drive shaft serves dual purposes: it functions as both the drive mechanism for the bicycle and as the mounting structure for the coaster brake actuator. The loop and lever element utilize the rotational motion of the pedal drive shaft to actuate the brake, making the drive shaft a multi-functional component that eliminates the need for separate brake actuation mechanisms
2Ease of operation
If a coaster brake system is implemented on electric bicycles with mid-motor designs, then the braking comfort and intuitiveness are improved, but the available space is consumed
Solution Approach 1:
The brake actuator components are nested within the existing pedal drive shaft assembly structure. The loop is mounted on the pedal drive shaft, the lever element is pivoted on the same shaft, and the entire mechanism fits within the compact space of the crank arm assembly, utilizing the existing structural envelope rather than requiring additional external space
Solution Approach 2:
The braking mechanism is combined with the pedal drive shaft assembly, utilizing the same structural space for both drive and brake actuation functions. This integration eliminates the need for separate brake housing and reduces the overall volume required for the braking system
3Device complexity
If a simple brake actuator design is used, then the space consumption is reduced, but the reliability of force transmission may be compromised
Solution Approach 1:
The loop is made from an elastic material with high tensile strength, changing the material parameters to provide both flexibility for the simple loop design and sufficient strength for reliable force transmission. The elastic properties of the loop material allow it to stretch and return, ensuring consistent force application to the brake while maintaining structural integrity
Solution Approach 2:
The loop acts as an intermediary element between the pedal drive shaft and the lever element. It transmits the rotational motion and force from the pedal drive shaft to the lever element, which then actuates the brake. This intermediary mechanism ensures reliable force transmission while maintaining the simplicity of the overall design
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
Enables the implementation of a simple, space-saving coaster brake system on electric bicycles, preventing wheel locking and providing overload protection, suitable for integration with anti-lock braking systems and existing braking systems.
Implementation Method 1
The loop is made of an elastic material with high tensile strength
Implementation Method 2
The loop is tensioned against the pedal drive shaft during a backpedaling motion
Implementation Method 3
a maximum holding force is reached beyond which the loop begins to slip again under frictional force
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The actuator has a strap (20) forming an interior space in which a pedal drive shaft (10) i.e. crankshaft, is extensively received. A lever (30) is supported in an inner space of a rotary bearing (32). The lever comprises a circular guide (62) arranged within the strap, which is stretched through the circular guide based on an angular position of the lever. A stopper (70) is arranged at a side of the lever opposite to an operation direction of the actuator and fixedly arranged opposite to the inner space. Independent claims are also included for the following: (1) a treadle gear comprising a support (2) a method for generating a brake actuator movement for a bicycle.