Worm-Gear Differential Locking for Low-NVH Self-Locking Axles
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Solution Overview
Problem
Conventional differential self-locking devices have complex structures, delayed response, high costs, and poor NVH characteristics, requiring high dimensional accuracy and consistency, leading to increased weight, noise, and component wear.
Innovation Solution
A differential self-locking device comprising a differential housing, half-shaft output gear set, upper and lower worm gear mechanisms, differential planetary gear set, worm gear shaft, brake pads, and positioning shaft sleeve, which are symmetrically disposed to convert large output torques into small input torques for automatic locking or unlocking, reducing weight and noise while improving component durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch device is disposed in the axis direction of the left and right half-shaft output gears to achieve differential locking, then the vehicle skidding problem is solved, but the structure becomes complex, control is complicated, response is delayed, and cost is high
Solution Approach 1:
The patent combines the differential mechanism and locking mechanism into a single integrated structure. The locking plates are directly coupled with the differential mechanism components (sun gears, planet gears, ring gears), eliminating the need for separate clutch devices and their associated control systems. This merging reduces structural complexity while maintaining the differential locking function.
2Reliability
If the Torsen differential A uses pairs of worm gears and two worms with six worm gears and twelve straight gears to achieve self-locking, then differential locking is achieved, but the radial size and weight become large, assembly requires very high dimensional accuracy, and components are easy to wear
Solution Approach 1:
The patent segments the locking function into multiple locking plates (first locking plate coupled to sun gear, second locking plate coupled to ring gear) that can independently engage with corresponding locking grooves. This segmentation allows for a more compact design compared to the Torsen differential's multiple worm gears, reducing both weight and radial size while maintaining the self-locking function through friction-based engagement.
3Reliability
If the Torsen differential A uses twelve straight gears with high dimensional accuracy requirements to achieve meshing, then differential locking is achieved, but manufacturing cost is high and assembly is difficult
Solution Approach 1:
The locking plates are designed with elastic deformation capability, allowing them to automatically adjust and engage with the locking grooves through their own elastic properties. This self-service mechanism eliminates the need for high-precision manual assembly and adjustment, making the manufacturing process simpler and more cost-effective while ensuring reliable engagement.
4Reliability
If conventional differential self-locking devices use complex clutch mechanisms to achieve locking, then differential locking is achieved, but noise, vibration, and harshness (NVH) performance is poor
Solution Approach 1:
The patent replaces the complex mechanical clutch engagement system with a friction-based locking mechanism using locking plates and locking grooves. This substitution eliminates the impact forces and mechanical shocks associated with clutch engagement, significantly reducing noise, vibration, and harshness while maintaining the differential locking function.
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 device achieves efficient automatic locking or unlocking, reduces weight and volume, optimizes NVH, and enhances component durability, making it economically viable with improved passing ability for vehicles.
Implementation Method 1
The brake pads are disposed on the worm gear shaft. The brake pads are respectively located at a top and a bottom of the upper worm gear and a top and a bottom of the lower worm gear.
Data Source
AI summary
A differential self-locking device includes a differential housing, a half-shaft output gear set disposed in the differential housing, an upper worm and worm gear mechanism, a lower worm and worm gear mechanism, a differential planetary gear set, and a worm gear shaft. The upper worm and worm gear mechanism and the lower worm and worm gear mechanism respectively convert a large output torque of the left half-shaft output gear and a large output torque of the right half-shaft output gear into small output torque thereof to lock the left half-shaft output gear and the right half-shaft output gear, thereby achieving automatic locking or unlocking of the differential self-locking device. A traction force of a vehicle is converted into torques of the left half-shaft output gear and the right half-shaft output gear, which improves passing ability of the vehicle.