Electric Axle Assembly Layout for Low-Floor Vehicle Access
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Solution Overview
Problem
There is a need for an electric axle assembly that minimizes floor height in low floor vehicles, such as buses and people carriers, to facilitate easier ingress and egress, particularly for disabled passengers and those with strollers, while integrating electric propulsion systems efficiently.
Innovation Solution
The electric axle assembly includes a suspension frame, drive assemblies with electric drive units and trains housed in cases, a drive module with a sealed enclosure and interconnects for power, control, and cooling, and isolation mounts to dampen forces, allowing compact and sealed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If drivetrain components are relocated to minimize floor height, then passenger ingress and egress is improved, but the complexity of integrating electric propulsion systems increases
Solution Approach 1:
The patent combines the electric drive unit, drive train, and control systems into an integrated electric axle assembly. The motor housing serves as the axle housing, and the drive unit is directly coupled to the drive train within the same housing, eliminating the need for separate mounting structures and reducing overall system complexity despite the relocated configuration.
Solution Approach 2:
The motor housing performs multiple functions: it houses the electric drive unit, contains the drive train, provides mounting points for suspension components, and serves as the axle housing. This multi-functionality reduces the number of separate components needed and simplifies the overall integration of the electric propulsion system.
2Reliability
If the drive module is sealed to protect electronics, then reliability is improved, but manufacturing and assembly complexity increases
Solution Approach 1:
The drive module is divided into separable components: the motor housing that contains the drive train, and the separate control system housing that contains the electronics. These modular sealed units can be manufactured and tested independently, then assembled together, reducing the complexity of creating a fully sealed integrated unit while maintaining protection of electronic components.
3Reliability
If isolation mounts are added to dampen forces, then reliability of the drive module is improved, but device complexity increases
Solution Approach 1:
The isolation mounts are integrated into the existing suspension frame structure rather than being separate add-on components. The suspension frame includes mounting points and structural elements that incorporate the isolation function, eliminating the need for additional dedicated isolation components while still providing force dampening protection to the drive module.
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 design enables a low floor height vehicle with efficient electric propulsion, improved passenger access, and reduced intrusions into the vehicle floor, while maintaining operational reliability and ease of maintenance.
Implementation Method 1
a biasing member arranged between the support tabs and configured to bias the support tabs away from one another
Data Source
AI summary
An electric axle assembly includes a suspension frame, a pair of drive assemblies coupled to opposite sides of the suspension frame, and a drive module coupled to the suspension frame. The drive module controls operation of the drive assemblies. The electric axle assembly is mounted to a vehicle frame and provides motive force to wheels of the vehicle for propelling the vehicle along a roadway.