Integrated Hub Motor Wheel Assembly With Nested Planetary Reducer
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Solution Overview
Problem
Conventional electric wheel assemblies for heavy-duty vehicles face challenges such as excessive space occupation, low efficiency, and reliability issues due to complex transmission components and inappropriate arrangement of motor and reducer, leading to unsprung mass and cooling difficulties.
Innovation Solution
An electric wheel assembly with an integrated hub motor, featuring a rim, hub, steering knuckle assembly, inner rotor motor, and planetary reducer, where the motor and reducer are optimally positioned to reduce size and mass, and a braking system is integrated to improve reliability and safety, utilizing a hollow rotor and direct oil cooling for efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a multi-stage reduction drivetrain is used, then the required reduction ratio can be achieved, but the overall transmission efficiency decreases and space occupation increases
Solution Approach 1:
The patent combines the motor and single-stage planetary reducer into an integrated hub motor assembly, merging previously separate components into a unified structure that achieves both the required reduction ratio and high transmission efficiency while reducing space occupation
Solution Approach 2:
The planetary reducer is nested within the motor housing, with the sun gear connected to the motor rotor holder and the planet carrier integrated with the hub, creating a compact nested arrangement that maximizes space utilization while maintaining efficient power transmission
2Ease of operation
If the motor and reducer are arranged in conventional configurations, then the drive function is achieved, but the hub bearings are unreasonably positioned and space for suspension and steering systems is insufficient
Solution Approach 1:
The patent repositions the hub bearings radially outward on the hub, changing their traditional axial positioning, which creates reasonable load paths and provides sufficient space for suspension and steering components while maintaining effective drive function
Solution Approach 2:
The hub serves multiple functions: it acts as the planet carrier for the reducer, provides mounting positions for hub bearings, and creates space for suspension and steering systems, making the component arrangement more versatile and space-efficient
3Strength
If the motor housing or components are overloaded, then structural strength may be sufficient, but the overall mass of the electric wheel increases
Solution Approach 1:
The patent applies local reinforcement only where needed in the motor housing and hub structure, rather than uniformly thickening all components, thereby maintaining necessary structural strength while minimizing overall mass increase
Solution Approach 2:
The patent employs composite material construction in the motor housing and hub components, combining materials with different properties to achieve optimal strength-to-weight ratio, ensuring structural integrity while reducing overall mass
4Ease of operation
If the braking system is arranged inappropriately, then braking function is achieved, but the electric wheel's reliability and safety are affected and heat affects motor performance
Solution Approach 1:
The patent extracts the braking system from the traditional wheel rim location and positions it independently on the hub, separating the braking function from the motor housing to prevent heat transfer to the motor while maintaining effective braking capability and reliability
Solution Approach 2:
The patent introduces thermal insulation barriers between the braking system and motor housing, using intermediary materials to prevent heat transfer from the brakes to the motor, thereby protecting motor performance while maintaining braking effectiveness
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 results in a compact, lightweight, and efficient electric wheel assembly with improved torque and power density, enhanced reliability, and effective heat management, allowing for better integration of suspension and steering systems within the wheel.
Implementation Method 1
a planetary reducer including: a sun gear connected to an end of the motor rotor holder close to the spoke plate and being the input end of the planetary reducer, and a planet carrier integrated with the hub and being the output end of the planetary reducer
Implementation Method 2
a braking system including a brake disc, the brake disc being fitted over the motor rotor holder through a brake disc connection sleeve and located at the end of the motor rotor holder away from the spoke plate, and the braking system being configured to brake the electric wheel assembly by braking the motor rotor holder
Implementation Method 3
the knuckle sleeve and the hub being provided with a hub bearing therebetween
Data Source
AI summary
An electric wheel assembly with an integrated hub motor includes a tire, a rim, a hub, a planetary reducer, an inner rotor motor, a braking system and a steering knuckle assembly. The inner rotor motor is provided in the rim, and its rotor is hollow and fitted over a motor rotor holder. An end of the motor rotor holder is mounted with a sun gear to transmit power to the planetary reducer, and the other end thereof is mounted with a brake disc. The planetary reducer employs a two-stage planet gear. The planetary reducer further includes a planet carrier integrated with the hub, serving as the reducer's power output end. The hub and the knuckle sleeve pass through the hollow motor rotor holder, and hub bearings are arranged thereamong. The inner rotor motor and the planetary reducer can employ an integrated direct oil cooling technology.