Inverted Motor Differential Assembly for Compact Vehicle Axles
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Solution Overview
Problem
Existing power transmission assemblies for vehicles are bulky and difficult to integrate into the limited space of a vehicle axle, particularly when transforming a two-wheel drive vehicle into a four-wheel drive or converting a combustion vehicle into an electric or hybrid vehicle.
Innovation Solution
A compact power transmission assembly with an inverted electric machine, where the rotor is radially outside the stator, and cogwheels are distributed around the electric machine, located inside the differential, allowing for easier installation and integration into vehicle axles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional power transmission assembly is installed in the rear axle, then the vehicle can be transformed into four-wheel drive or electric/hybrid configuration, but the assembly is bulky and difficult to integrate into the limited space of the vehicle axle
Solution Approach 1:
The electric machine is positioned inside the differential housing, with the rotor radially outside the stator. The cogwheels are distributed around the electric machine, creating a nested configuration where multiple components occupy overlapping spatial envelopes. This allows the power transmission assembly to be integrated within the existing differential space without requiring additional external mounting volume.
Solution Approach 2:
The electric machine uses an inverted configuration where the rotor is radially outside the stator, contrary to conventional electric motor design. This inversion allows the stator to be mounted on the differential housing while the rotor rotates within the available space, optimizing the use of the differential volume and reducing overall assembly size.
2Ease of manufacture
If the electric machine is positioned outside the differential, then installation is easier, but the assembly becomes bulky and occupies excessive space in the vehicle axle
Solution Approach 1:
The electric machine components are nested within the differential housing structure. The stator is mounted on the housing while the rotor rotates inside, and the cogwheels are positioned around the rotor. This nested arrangement allows all components to be installed through the existing differential opening without requiring separate external mounting operations.
3Volume of moving object
If a compact design is used, then the assembly fits better in the vehicle axle, but the manufacturing and assembly complexity increases
Solution Approach 1:
The differential housing serves multiple functions: it houses the differential mechanism, mounts the stator of the electric machine, and provides the structural framework for the entire power transmission assembly. The rotor shaft simultaneously serves as the rotation axis for the electric machine and the input shaft for the differential. This multi-functionality reduces the number of separate components and simplifies assembly.
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 compact design facilitates the transformation of vehicles into four-wheel drive or hybrid configurations with improved energy efficiency and reduced mechanical losses, optimizing the operation of combustion engines and enabling substantial energy savings.
Implementation Method 1
an electric machine comprising a stator fixed relative to the vehicle and a rotor movable in rotation relative to a rotation axis of said electric machine, said electric machine being intended to transmit motive power and its rotation to the wheels
Implementation Method 2
a differential comprising at least one differential input connected to the rotor of the electric machine, said differential comprising a plurality of cogwheels connected with each other to distribute the differential input power between: a first output intended to be connected to a first power transmission shaft transmitting power to a first wheel, and a second output intended to be connected to a second power transmission shaft transmitting power to a second wheel, the distribution being a function of the rotation speed of the first output and second output
Data Source
AI summary
Power transmission assembly for a vehicle comprising an electric machine, and a differential connected to the electric machine. The electric machine is an inverted machine in which the rotor is radially outside the stator with respect to the rotation axis of the electric machine. The differential consists of cogwheels distributed around the electric machine.