Reciprocating Crank Transmission With Continuous Bidirectional Torque
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Solution Overview
Problem
Conventional crank systems face inefficiencies due to limited crank length, which affects biomechanical performance, torque generation, and limb movement, particularly at low RPMs, and are unable to simultaneously transmit push and pull torques effectively.
Innovation Solution
A mechanical device using unidirectional couplings and a reversing mechanism allows cranks to move in reciprocating motion, enabling torque transmission in the desired direction, allowing for variable crank timing and length, and simultaneous application of pushing and pulling forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If crank length is increased to improve torque generation, then torque output increases, but biomechanical performance deteriorates due to incorrect postures and improper limb movements
Solution Approach 1:
The crank system is segmented into two independent cranks (first crank and second crank) that can operate independently and reciprocally. Each crank can be optimized for different functions: one for power generation and the other for biomechanical efficiency, allowing long cranks for torque without compromising user posture
Solution Approach 2:
Instead of requiring both cranks to rotate in the same direction (conventional system), the invention uses a reversing mechanism that makes the second crank rotate in the opposite direction to the first crank. This inversion allows both cranks to be timed at 180 degrees while maintaining proper biomechanical alignment for each crank position
2Ease of operation
If crank length is decreased to improve biomechanical performance, then ease of operation improves, but torque generation deteriorates because crank length is directly proportional to driving torque
Solution Approach 1:
The invention merges the functions of two cranks operating in reciprocal motion through a reversing mechanism. Both cranks contribute to torque generation simultaneously, effectively doubling the torque output potential while each crank maintains optimal length for biomechanical performance
Solution Approach 2:
The reciprocating motion system with unidirectional couplings ensures continuous torque transmission throughout the entire cycle. Both cranks are actively contributing to torque generation at all times, eliminating dead centers and maintaining continuous useful action without requiring excessive crank length
3Device complexity
If cranks are timed at 180 degrees in conventional circular motion, then device complexity is reduced, but torque transmission deteriorates due to fixed cycle limitations and active dead center limits
Solution Approach 1:
The invention introduces dynamic adaptability through unidirectional couplings and a reversing mechanism that allows crank timing to be adjusted independently for each crank. The system transitions from fixed 180-degree timing to flexible, adjustable timing while maintaining the simplicity of 180-degree configuration when needed
Solution Approach 2:
The crank timing parameters can be changed independently for each crank through the reversing mechanism and unidirectional couplings. This allows optimization of torque transmission by adjusting the phase relationship between cranks without increasing overall device complexity
4Force
If unidirectional couplings and reversing mechanism are added to enable reciprocating motion, then torque generation improves, but device complexity increases
Solution Approach 1:
The reversing mechanism acts as an intermediary between the two cranks, enabling reciprocating motion without requiring complex direct coupling. The unidirectional couplings serve as intermediaries that selectively transmit torque only in the desired direction, simplifying the overall transmission path
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
The device enhances biomechanical performance by increasing torque generation, improving stability and flexibility, and allowing for continuous torque transmission with minimal oscillations, even with longer crank lengths, and supports power-assisted pedaling.
Implementation Method 1
a first unidirectional joint (7a) connected to said first crank (6); a second unidirectional joint (7b) connected to said second crank (1), said unidirectional joints being adapted to lock said cranks (1, 6) with said shaft (8) when said cranks are actuated by a user in a predetermined direction and are such to disengage said cranks from said shaft when said cranks are actuated in the opposite direction
Implementation Method 2
a reversing element comprising a kinematic mechanism adapted to engage with said first transmission element and said second transmission element and adapted to force said cranks to rotate in opposite directions, characterized in that said kinematic motion is of the parallel axis type and adapted to supply continuous driving torque to said shaft
Data Source
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AI summary
A mechanical system designed to convert, by means of the use of cranks or levers, the force expressed by a user into a driving torque applied to a drive shaft by converting the reciprocating motion of the cranks into a circular motion. The mechanical system of the invention makes it possible to generate effective torque on the employed cranks either with a force applied simultaneously to the cranks or with a force applied alternately to the cranks, where the applied force can be a pulling force or a pushing force.