Wheel Hub Drive Layout With Dual Planetary Gear Reduction
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Solution Overview
Problem
Existing wheel hub driving systems for heavy-duty vehicles suffer from complex assembly, high manufacturing costs, low transmission efficiency, and large energy loss due to multiple transmission components and heavy system weight, particularly in central motor and hub motor drives.
Innovation Solution
A wheel hub driving system with a simple structure and modular design, incorporating two planetary gear sets and a brake device, where the primary and secondary sun gears are connected to the wheel hub bearing, allowing for a large gear ratio and efficient power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a central motor drive with multiple transmission components is used, then the vehicle can achieve multiple gear ratios, but the system weight increases and transmission efficiency decreases
Solution Approach 1:
The transmission system is divided into two separate planetary gear sets (first and second planetary gear sets) with different reduction ratios. Each gear set can operate independently or in combination, allowing the system to achieve multiple gear ratios (first gear ratio from first planetary gear set, second gear ratio from second planetary gear set, and third gear ratio from combined operation) while maintaining a compact structure with reduced component count compared to traditional multi-component transmission systems
2Volume of moving object
If a hub motor drive with differential planetary gear reducer is used, then the vehicle can achieve compact design, but the assembly complexity increases due to coupled gear design
Solution Approach 1:
The drive assembly is segmented into modular components: a hub motor, a wheel hub bearing, and two independent planetary gear sets. The first planetary gear set includes a first sun gear, first planet carrier, and first geared ring, while the second planetary gear set includes a second sun gear, second planet carrier, and second geared ring. This modular segmentation allows each component to be designed and manufactured independently, significantly reducing assembly complexity while maintaining compact overall dimensions
Solution Approach 2:
The planetary gear sets are nested within the wheel hub bearing structure. The first sun gear and second sun gear are both sleeved around the periphery of the wheel hub bearing, and the geared rings are positioned within the bearing assembly. This nested arrangement achieves compact design by utilizing the internal space of the wheel hub bearing, while the modular nature of each gear set keeps assembly complexity manageable
3Volume of moving object
If a cycloidal gear reducer is used in wheel hub driving system, then the vehicle can achieve compact structure, but the manufacturing cost increases and transmission efficiency decreases
Solution Approach 1:
Instead of using a complex cycloidal gear mechanism, the invention employs two standard planetary gear sets with different reduction ratios. Planetary gear sets are well-established, standardized components with成熟 manufacturing processes and lower production costs. By segmenting the reduction function into two independent planetary gear sets, the system achieves compact structure while avoiding the high manufacturing costs and low transmission efficiency associated with cycloidal gear reducers
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 system achieves high transmission efficiency with a short transmission chain, supports modular design, and reduces the size and weight of the brake device by amplifying braking torque through planetary gear sets, while maintaining a simple structure.
Implementation Method 1
a first planetary gear set comprises a primary sun gear, a primary planet carrier and a primary geared ring; a second planetary gear set comprises a secondary sun gear, a secondary planet carrier and a secondary geared ring
Implementation Method 2
the wheel hub bearing comprises a middle axle, a rolling body and an outer ring
Data Source
AI summary
A wheel hub driving system, including a housing, an electric motor, two planetary gear sets and a wheel hub bearing. The wheel hub bearing has a middle axle and an outer ring, the middle axle is fixed relative to the housing, and both a primary sun gear and a secondary sun gear are sleeved around the periphery of the wheel hub bearing. A stator of the electric motor, a primary geared ring and a secondary geared ring are all fixed to the housing. A rotor of the electric motor is anti-torsionally connected to the primary sun gear. A primary planet carrier is anti-torsionally connected to the secondary sun gear, a secondary planet carrier is anti-torsionally connected to the outer ring and the outer ring is configured to be anti-torsionally connected to a wheel rim so as to transmit power from the electric motor to the wheel rim.