Ebike Bottom Bracket Drive Damping Device for Shift Shock Reduction

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Solution Overview

Problem

Existing bottom bracket drives in two-wheelers, particularly eBikes, experience mechanical shock and noise during gear shifting due to abrupt braking of gear wheels, leading to component stress and noise pollution.

Innovation Solution

Integration of a gearbox with an electric motor for automatic shifting and a damping device between the gear and shift gate to absorb impact energy, using a damping device such as a spring or elastomer to reduce mechanical and noise loads, allowing for cheaper production and extended component lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If gear wheels are abruptly braked during shifting, then gear ratio switching is achieved, but mechanical shock and noise load increase

Engineering Contradiction:
Improveshifting speedVSAvoidshock and noise load
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

A damping device is integrated into the shift gate mechanism to cushion the impact before the blocking element fully engages with the shift finger. The damping device includes a damping element arranged between the shift gate and blocking element, which absorbs impact energy during the shifting process, reducing mechanical shock and noise while maintaining fast shifting performance

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If damping device is added to reduce shock, then component life expectancy increases, but device complexity increases

Engineering Contradiction:
Improvecomponent life expectancyVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The damping device is merged with the existing shift gate structure. The damping element is integrated into the shift gate assembly, combining the shifting function and damping function into a single integrated component. This reduces overall system complexity while providing shock absorption to extend component life

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

A damping element serves as an intermediary component between the shift gate and blocking element. This intermediary absorbs impact energy during engagement, protecting other components from shock loads while maintaining the simplicity of the overall shifting mechanism

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of time

If blocking element engages shift finger abruptly, then gear shifting is completed quickly, but contact noise increases

Engineering Contradiction:
Improveshifting timeVSAvoidcontact noise
Core Design Contradiction:
Loss of timeVSObject-generated harmful factors

Solution Approach 1:

The damping element is positioned to engage before the blocking element fully contacts the shift finger, cushioning the impact in advance. This maintains quick shifting while significantly reducing contact noise and mechanical shock during the engagement process

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 effectively reduces shock and noise loads during shifting, enabling the use of cheaper materials and manufacturing processes while enhancing the driving experience by minimizing mechanical stress on components.

Implementation Method 1

a damping device, with the damping device between the gear and the Shift gate dampens the shift shock. The damping device thus absorbs part of the impact energy

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the damping device is a spring, an elastomer, a pneumatic damper, a plastic or the like

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3444177B1Bottom bracket drive of a vehicle, and a vehicle comprising such a bottom bracket drive
Publication Date: 2020.02.26 ROBERT BOSCH GMBH
  • EP3444177B1 patent drawingFigure 1
  • EP3444177B1 patent drawingFigure 2~3
  • EP3444177B1 patent drawingFigure 4a~4b

AI summary

The present invention relates to a bottom bracket drive (2) of a vehicle (1), in particular a two-wheeler, comprising an electric vehicle drive (3), a transmission (4), a shift gate (6), an electric drive (7) for actuating the shift gate (6), and a damping device (10), wherein the damping device (10) dampens the shift shock between the transmission (4) and the shift gate (6).