Hybrid Vehicle Transaxle Axial Dimension Reduction
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Solution Overview
Problem
In hybrid electric vehicles, the axial dimension of the transaxle is increased due to the need for layshaft gearing and conventional torsion dampers when components are located on three axes, and supporting motors and generators with axially-spaced bearings further exacerbates this issue.
Innovation Solution
The transaxle design incorporates a splitter gearset, traction gearset, chain drive, and a torsion bar damper that is axially extended within the input, with components supported by needle and ball bearings to minimize axial space, allowing the transaxle to efficiently transmit power to vehicle wheels while maintaining optimal gearset efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If layshaft gearing is used to transmit power between the differential and engine axis, then power transmission is achieved, but the axial dimension of the transaxle increases
Solution Approach 1:
The patent removes the layshaft gearing intermediate component and directly connects the engine axis to the differential through simplified planetary gearsets. This extraction of the unnecessary intermediate transmission mechanism eliminates the axial space requirement while maintaining power transmission functionality between the engine and differential.
Solution Approach 2:
The patent repositions all major components (engine, electric generator, traction motor, and planetary gearsets) onto a common axis, transitioning from a three-axis configuration to a single-axis arrangement. This dimensional reorganization eliminates the need for axial power transfer mechanisms and minimizes the overall axial dimension of the transaxle.
2Object-affected harmful factors
If a conventional torsion damper is located between the engine and electric generator, then vibration damping is provided, but the axial dimension increases
Solution Approach 1:
The torsion damper is nested within the electric generator assembly, specifically positioned inside the generator housing or integrated with the generator rotor structure. This nested arrangement allows the damping function to be provided without adding external axial length, as the damper occupies space already allocated for the generator components.
Solution Approach 2:
The torsion damper function is merged with the electric generator assembly by integrating the damper structure with the generator housing or mounting system. This combination eliminates the need for a separate axial space allocation for the damper, as it becomes part of the generator's structural assembly rather than a distinct component.
3Reliability
If the electric generator is supported on the case wall using two axially-spaced bearings, then support is provided, but the axial dimension increases
Solution Approach 1:
The electric generator is repositioned to be supported on the common axis rather than on the case wall. By moving the support location from the radial direction (case wall) to the axial direction (common axis), the generator can be accommodated within the axial space already required for other components, eliminating additional axial length.
Solution Approach 2:
The common axis structure serves multiple functions: it supports the engine, electric generator, traction motor, and planetary gearsets simultaneously. This multi-functional axis eliminates the need for separate support structures for each component, thereby minimizing the overall axial dimension while maintaining reliable support for all elements.
4Reliability
If two additional axially-spaced bearings are used to support the traction motor, then support is provided, but the axial dimension increases
Solution Approach 1:
The traction motor is repositioned to be supported on the common axis rather than requiring separate axial support bearings. This dimensional reorganization allows the motor to be integrated into the axial arrangement of other components, eliminating the need for additional axial space for support bearings.
Solution Approach 2:
The common axis structure provides universal support for all major components including the engine, electric generator, traction motor, and planetary gearsets. This multi-functional support system eliminates the need for separate bearing assemblies for each component, thereby minimizing axial dimension while ensuring reliable support.
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 reduces the axial dimension of the transaxle, enabling efficient power transmission to vehicle wheels while maintaining optimal efficiency of the planetary gearsets and reducing the overall length of the transaxle.
Implementation Method 1
The torsion bar damper is fitted within the input and extends axially along the main axis of the transaxle
Implementation Method 2
The torsion bar damper is fitted within the input and extends axially along the main axis of the transaxle, thereby saving axial space
Implementation Method 3
The traction motor, electric generator and, planetary gearing are supported by needle bearing on the input
Implementation Method 4
A pulley of the chain drive is supported by a ball bearing also on the input
Data Source
AI summary
A vehicle transaxle includes an input, a splitter gearset including a member connected to the input, a second member connected to a motor-generator and a first output, a traction gearset including a third member connected to a traction motor, a fourth non-rotating member and a second output, a chain drive connected to the first and second outputs, and a differential driven by the chain drive for transmitting power to vehicle wheels.