Vehicle Hatch Drive Double Transmission Unit

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Solution Overview

Problem

Existing electric tailgate drives face challenges with complex assembly, noise due to high-speed components, and limited space efficiency, particularly with multi-stage planetary gears.

Innovation Solution

A compact, low-noise drive device using a double transmission unit with worm stages for gear reduction, allowing for axial shortening while maintaining radial space efficiency and enabling manual operation in case of motor failure through multi-threaded worms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multi-stage planetary gears are used for speed reduction, then gear reduction ratio is achieved, but device complexity increases and assembly becomes complex

Engineering Contradiction:
Improvegear reduction ratioVSAvoidnumber of components
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The transmission device is divided into multiple independent gear stages (first gear stage, second gear stage, third gear stage) that can be separately manufactured and assembled. Each stage performs a specific speed reduction function, allowing modular design and simplified assembly compared to integrated planetary gear systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Intermediate shafts (first intermediate shaft, second intermediate shaft) are introduced to transfer power between gear stages. These intermediary components simplify the transmission path and allow each gear stage to be optimized independently while maintaining overall system compactness.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If multi-stage planetary gears are used for speed reduction, then gear reduction ratio is achieved, but radial space requirement increases

Engineering Contradiction:
Improvegear reduction ratioVSAvoidradial space
Core Design Contradiction:
PowerVSArea of stationary object

Solution Approach 1:

The transmission device extends primarily in the axial direction rather than radially. Multiple gear stages are arranged sequentially along the axial dimension, allowing high gear reduction ratios to be achieved without increasing radial footprint. The housing elongates axially to accommodate the staged gear reductions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Power

If first planetary stage rotates at high speed, then power transmission is efficient, but noise development increases

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoidnoise
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The power transmission path is segmented into multiple gear stages, each operating at progressively lower speeds. The first gear stage receives high-speed input but immediately reduces it, and subsequent stages operate at even lower speeds. This segmentation distributes the speed reduction across stages, reducing noise from any single gear mesh while maintaining overall power transmission efficiency.

Inventive Principle:
Principle #1Segmentation

4Length of moving object

If axial length is reduced, then compactness is improved, but transmission path becomes constrained

Engineering Contradiction:
Improveaxial lengthVSAvoidtransmission path arrangement
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The transmission device optimizes the ratio between axial length and radial width. While the axial length is reduced compared to conventional designs, the device utilizes radial space efficiently through compact gear stage arrangement. The housing dimensions are optimized to provide adequate space for the transmission path while maintaining overall compactness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 provides a quieter, simpler design with reduced component count, ensuring efficient gear reduction and manual operability, even if the electric motor fails, while maintaining compact dimensions.

Implementation Method 1

a low-noise gear with only a small number of components can be used as the double gear unit, which gear has in particular at least one worm stage

Methodology Applied
Scientific EffectWorm drive: Worm Drive

Implementation Method 2

If the worm of the worm stage is provided with only one gear, self-locking occurs, which prevents manual operation. In the case of multi-threaded screws, on the other hand, a through-torque can be applied manually

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2454434B1Drive device of a vehicle component, particularly a body hatch
Publication Date: 2013.11.13 ROBERT BOSCH GMBH
  • EP2454434B1 patent drawingFigure 1

AI summary

The invention relates to a drive device in vehicle component, comprising an electric drive motor, the armature shaft thereof being connected to a gearbox device for driving an output shaft. The gearbox device comprises at least one double gearbox unit, made of two gear stages having two changes in direction.