Multi-stage Planetary Gear Drive Assembly for E-bikes
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Solution Overview
Problem
Existing drive arrangements for vehicles, particularly electric bicycles and pedelecs, face issues with increased size, inefficiency, lack of power shifting capability, interruptions in tractive force, and idle travel due to friction ring gears and hub gear systems.
Innovation Solution
A drive arrangement featuring a multi-stage planetary gear system with automatically switchable sun gears and driver elements arranged radially and axially outside the sun wheel, allowing for efficient torque transmission with minimal losses and no interruption in traction, and incorporating freewheels to prevent idle travel during shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If friction ring gears or hub gear systems are used, then the drive arrangement can transmit torque, but the size increases and efficiency decreases
Solution Approach 1:
The planetary gear system nests multiple gear stages within a compact configuration, with sun gears, planet gears, and ring gears arranged concentrically around a common axis. This nesting allows multiple transmission ratios to be achieved within a small volume, resolving the contradiction between compact size and efficient torque transmission.
Solution Approach 2:
The invention transitions from traditional lateral gear arrangements to an axial configuration where planetary gears rotate around a central axis. This dimensional reorganization allows the driver element to engage sun gears axially rather than radially, reducing the radial footprint while maintaining transmission efficiency.
2Productivity
If traditional gear systems are used, then torque can be transmitted, but power shifting capability is lacking and tractive force is interrupted
Solution Approach 1:
The planetary gear system maintains continuous torque transmission through the planet gears that constantly engage with both the sun gear and ring gear. During shifting operations, the carrier continues to rotate, ensuring uninterrupted tractive force delivery to the output, thereby enabling power shifting without loss of propulsion.
Solution Approach 2:
The system dynamically adjusts transmission ratios by selectively engaging or disengaging sun gears through the driver element while maintaining continuous rotation of the planetary carrier. This dynamic capability allows smooth transitions between gear ratios without interrupting the power flow, enabling reliable power shifting.
3Volume of moving object
If driver elements are positioned close to the sun gear axis, then the structure is compact, but forces increase and wear occurs
Solution Approach 1:
The driver element is repositioned from a radial arrangement to an axial arrangement, where it engages the sun gear from the axial direction rather than from the radial direction. This dimensional change allows the driver element to be positioned at the periphery of the planetary gear system, increasing the lever arm and reducing the forces required for engagement while maintaining structural compactness.
4Adaptability or versatility
If multi-stage planetary gear is used, then transmission ratio can be varied, but device complexity increases
Solution Approach 1:
The planetary gear system serves multiple functions simultaneously: it provides multiple transmission ratios through different sun gear engagements, maintains continuous torque transmission, and enables compact packaging. The same planetary carrier and planet gears facilitate all gear changes, reducing the need for additional shifting mechanisms and simplifying the overall device complexity.
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 solution enables efficient, compact, and reliable torque transmission with reduced wear and no interruption in traction, providing a high number of selectable gears and a smooth shifting experience.
Implementation Method 1
a multi-stage planetary gear (21) which can be switched automatically and by itself and which has a variable transmission ratio (i)
Implementation Method 2
a drive arrangement (80) for a vehicle that can be driven with muscle power and/or - additionally - with motor power
Implementation Method 3
The respective driver element (64) is arranged radially and/or axially outside of at least the respectively coupled sun wheel (55, 56) with respect to the axis of rotation (Y) of the sun wheel
Data Source
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AI summary
The present invention relates to a drive arrangement (80) of a vehicle (1) powered by muscle power and/or - in particular additionally - powered by motor power, an electric bicycle, e-bike, pedelec or the like, with a crankshaft (15) rotatable about an axis of rotation (Y) for receiving a first torque, in particular generated by muscle power, and with a transmission device (20) which is designed to transmit the first torque from the crankshaft (15) to an output element (4) that can be coupled to a drive wheel (9-2) of the vehicle (1) and by means of a multi-stage planetary gear (21) that can be switched, in particular automatically, to a variable transmission ratio, in which the transmission ratio of the planetary gear (21) is changed by means of a gear shift and by controlled connection and/or release of respective sun gears (55, 56) corresponding planetary stages (57, 58) via a connection with the respective sun gear (55,56) the drive element (64) is rotatably coupled and is adjustable, and the respective drive element (64) is arranged radially and/or axially outside the respective coupled sun gear (55, 56).