Nested Planetary Axle Drive for Compact Differential Packaging
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Solution Overview
Problem
Existing axle drives require significant axial installation space due to the use of multiple planetary gear mechanisms, which limits their compactness and efficiency in transmitting drive torque to output shafts while allowing for differential speed adjustments.
Innovation Solution
The design incorporates two coaxially arranged planetary gear mechanisms, where the internal gear of the first mechanism forms the sun gear of the second, enabling compact axial layout and differential function by using a shared external toothing system, with helical toothing on both sides to compensate for axial forces and facilitate torque transmission to both output shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gear mechanisms are used to transmit drive torque to output shafts, then the differential function and speed transmission are achieved, but the axial installation space increases
Solution Approach 1:
The patent combines two planetary gear mechanisms coaxially around a common drive shaft, with the internal gear of the first mechanism forming the sun gear of the second mechanism. This merging approach allows both differential functions to be achieved while sharing common components (drive shaft, internal gear), thereby reducing the overall axial installation space compared to using separate planetary gear mechanisms
Solution Approach 2:
The second planetary gear mechanism is arranged radially on the outside coaxially around the first planetary gear mechanism, creating a nested configuration. The internal gear of the first mechanism serves as the sun gear for the second mechanism, effectively nesting the two mechanisms together and minimizing axial space requirements
2Length of moving object
If two planetary gear mechanisms are arranged coaxially to reduce axial space, then the axial installation space is reduced, but the complexity of gear toothing configuration increases
Solution Approach 1:
The internal gear of the first planetary gear mechanism serves dual functions: it acts as the ring gear for the first mechanism and simultaneously serves as the sun gear for the second planetary gear mechanism. This multi-functionality reduces the total number of separate components needed while achieving the desired compact coaxial arrangement
Solution Approach 2:
By equating the internal gear of the first mechanism with the sun gear of the second mechanism, the patent merges two separate gear configurations into a unified structure. This reduces the number of independent toothing systems from four (two sun gears, two ring gears) to three, simplifying the overall gear configuration
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
This configuration allows for efficient speed transmission and differential operation with reduced axial length, enabling compact designs and adjustable rotational speeds between output shafts, while maintaining torque balance and compensating for axial forces.
Implementation Method 1
the internal gear of the first planetary gear mechanism has a toothing system, in particular a helical toothing system, on its outer side and/or on its inner side
Data Source
AI summary
An axle drive, comprising a drive shaft, a first output shaft and a second output shaft, a first planetary gear mechanism and a second planetary gear mechanism, it being possible for a drive torque of the drive shaft to be transmitted by means of the first planetary gear mechanism and the second planetary gear mechanism to the first and second output shaft, wherein the second planetary gear mechanism is configured radially on the outside coaxially around the first planetary gear mechanism, the internal gear of the first planetary gear mechanism forming the sun gear of the second planetary gear mechanism.