Ratcheting Bicycle Pedal Mechanism for Higher Torque at Constant Cadence
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Solution Overview
Problem
Bicycles face challenges in maintaining speed and reducing physical fatigue during uphill climbs and headwinds due to the need for increased pedal rotation speed, and existing gear systems cause discomfort and difficulty in shifting.
Innovation Solution
A pedal device with a pinion gear and movable pedal plate that uses a ratchet mechanism to enhance rotational force by synchronizing the rack gear with the pedal shaft rotation, allowing for efficient torque transmission and reduced physical effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If gear ratio is reduced to alleviate burden on legs during uphill climbs or headwinds, then physical strain is reduced, but pedal rotation speed must be increased to maintain speed, resulting in significant sacrifice in speed
Solution Approach 1:
The pedal incorporates a movable pedal plate that can dynamically adjust its position between an open state and a closed state, changing the effective lever arm length during pedaling. This dynamic adjustment allows the system to optimize the balance between force multiplication and rotation speed based on the pedaling phase and external conditions.
Solution Approach 2:
The invention changes the geometric parameter of the pedal system by adjusting the distance between the pedal axis and the movable pedal plate axis. This parameter change enables the force point to shift position, thereby modifying the torque arm length and achieving variable mechanical advantage without requiring gear changes.
2Power
If oval-shaped chainrings are used to efficiently transmit force, then force transmission efficiency is improved, but discomfort is caused by changes in angular velocity depending on pedal position
Solution Approach 1:
The invention extracts the force transmission function from the chainring and transfers it to the pedal mechanism itself. By using the movable pedal plate and pinion-rack mechanism, the force transmission is achieved directly at the pedal interface, eliminating the need for oval-shaped chainrings and their associated angular velocity variations.
3Force
If conventional ratchet mechanism is used, then rotational force is enhanced, but the mechanism loses function when teeth disengage due to crank rotation
Solution Approach 1:
The invention ensures continuous engagement between the rack gear and pinion gear by designing the movable pedal plate to maintain contact throughout the cranking motion. The rack gear is suspended to follow the rotation of the pinion gear, ensuring that the teeth remain engaged and the ratchet mechanism continues to function throughout approximately half a crankshaft rotation.
Solution Approach 2:
The movable pedal plate acts as an intermediary element that transmits the cranking motion to the rack gear while maintaining continuous engagement. It serves as the mediator between the pedal rotation and the ratchet mechanism, ensuring smooth and continuous force transmission without disengagement.
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 provides a 24% increase in torque, reducing physical fatigue while maintaining constant cadence, and allows for smoother riding with fewer gear changes, extending range on electric bicycles and flight duration on human-powered aircraft.
Implementation Method 1
During pedaling, the opening and closing motion of the movable pedal creates a ratchet mechanism between the rack gear and the pinion gear. When meshed, the rotation of the pedal axle in the forward direction is locked
Implementation Method 2
the rack gear, which is linked to the pedal, maintains engagement with the pinion gear by rotating in a manner that follows and pushes the pinion gear
Data Source
AI summary
A pedal rotational force strengthening device for efficiently transmitting leg force is inexpensively provided. A pinion gear is attached to a pedal shaft, a shaft is provided at the front end of the pedal, a movable tread biased so that the rear opens is pivotally attached to the shaft, and a rack gear biased so as to mesh with the pinion gear is suspended in front of the lower part of the tread a via the shaft, whereby the opening/closing operation of the movable tread during pedaling creates a ratchet mechanism between the rack gear and the pinion gear, the forward axial rotation of the pedal is locked during meshing, and the force point of the pedal moves from the axial center to the front end, so that the rotational force can be strengthened. When this device is used for a bicycle, a light and powerful ride can be enjoyed simply by replacing the pedals.