Perpendicular E-Drive Layout With Hypoid Reduction for Compact EV Axles
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Solution Overview
Problem
Conventional electric vehicle drive designs, particularly for compact vehicles, face issues of complexity, weight, cost, and inefficiency due to asymmetric weight distribution and heat radiation, with wheel-adjacent motor configurations unsuitable for modern electric passenger vehicles.
Innovation Solution
A powertrain configuration with an electric motor oriented perpendicular to the wheel axis, using a single-stage or dual-stage hypoid transmission with a bevel gearset or planetary-hypoid reduction, optimizing gear ratios and orientations to achieve symmetric weight distribution, reduced heat exposure, and efficient energy recuperation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wheel-adjacent motor configurations are used, then each driven wheel has dedicated motor and transmission, but complexity, weight and cost increase significantly
Solution Approach 1:
The patent combines multiple drive units into a single integrated transmission system located at the front axle. The transmission includes a differential case with planet gears that simultaneously drive both front wheels, merging what would traditionally be separate wheel-adjacent motor-transmission assemblies into one centralized unit. This reduces overall system complexity while maintaining the ability to independently control each wheel's power delivery.
2Volume of moving object
If inline design with motor parallel to wheel axis is used, then compact packaging is achieved, but width between wheels increases and asymmetric weight distribution occurs
Solution Approach 1:
The patent employs asymmetric planetary gear arrangements within the differential case to achieve symmetric weight distribution. The planet gears are positioned and sized asymmetrically relative to the differential axis, allowing the transmission to deliver equal torque to both wheels while maintaining a compact footprint. This asymmetric internal geometry compensates for the asymmetric mounting position, resulting in balanced weight distribution across the vehicle.
3Volume of moving object
If inline design with motor parallel to wheel axis is used, then compact packaging is achieved, but heat radiation to wheel and tire increases temperature by 10-20°C
Solution Approach 1:
The patent extracts the heat-generating motor from close proximity to the wheels and positions it centrally at the front axle. The transmission system is designed with the motor mounted perpendicular to the wheel axis, separating the motor's thermal output from the wheel and tire assembly. This spatial extraction of the heat source prevents direct thermal coupling between the motor and wheels, eliminating the 10-20°C temperature increase that would otherwise occur.
4Length of moving object
If short drive shafts with two CV-joints are used, then width between wheels is reduced, but CV-joints wear fast due to steering inclination and control arm swings
Solution Approach 1:
The patent extracts the CV-joints from the drive shaft assembly and relocates them to the wheel hub area. The drive shafts are extended to reach the wheels directly from the central transmission, eliminating the need for intermediate CV-joints in the traditional locations. This repositioning removes the stress points caused by steering inclination and control arm swings, significantly improving joint durability.
5Shape
If asymmetric weight distribution is offset with other asymmetric vehicle components, then balance is partially achieved, but negative influence on dynamic behavior remains
Solution Approach 1:
The patent uses asymmetric planetary gear configurations within the differential to achieve symmetric torque distribution to both wheels. The planet gears are arranged asymmetrically relative to the differential axis, with different gear ratios and positioning on each side. This internal asymmetry compensates for any external asymmetric mounting, ensuring that weight distribution and torque delivery are balanced, thereby preserving optimal vehicle dynamic behavior.
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 compact, cost-effective, and efficient electric drive system with optimal packaging, symmetric weight distribution, and reduced heat radiation, enhancing motor efficiency and energy recuperation capabilities.
Implementation Method 1
The drive shaft is mechanically connected to the axes of the wheels via a transmission comprising at least one pair of mating gears, one of the pair of mating gears being an offset pinion
Data Source
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AI summary
A powertrain of a vehicle comprising an electric motor (16) having a drive shaft (11) wherein the drive shaft is oriented preferably perpendicular to the common axis (Aw) of the wheels (18) which the powertrain is intended to drive (i.e. rotate). The drive shaft of the electric motor is mechanically connected to the axles (20, 22) of the wheels, which are aligned with the common axis, via a transmission (10) having at least one pair of mating gears (12, 14), preferably with one of the pair of mating gears being an offset pinion (14), and with the reduction ratio of the transmission being in the range of about 6 to about 15 with the pinion having 2 to 6 teeth.