Differential Bearing Layout to Reduce Drag and Gear Deflection
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Solution Overview
Problem
Existing differential assemblies in vehicles suffer from drag losses and reliability issues due to the need for pre-load in tapered rolling bearings, which can lead to poor gear mesh contact and skewness under radial loads.
Innovation Solution
A differential assembly that uses a bearing assembly comprising a cylindrical roller bearing and a ball bearing, where the cylindrical roller bearing is arranged closer to the ring gear, eliminating the need for pre-load and minimizing drag losses, while the ball bearing supports axial loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tapered rolling bearings are used in the bearing assembly, then the bearing assembly can take up both axial and radial loads with stable setup and great durability, but drag losses increase due to the need for pre-load
Solution Approach 1:
The bearing assembly is segmented into two separate bearing types: cylindrical roller bearings for radial loads and ball bearings for axial loads. This segmentation eliminates the need for pre-load in tapered roller bearings, thereby reducing drag losses while maintaining the ability to handle both radial and axial loads effectively.
2Stability of the object's composition
If tapered rolling bearings are used in the bearing assembly, then the bearing assembly provides stable setup, but the shimming process is required to set the pre-load
Solution Approach 1:
The complex shimming process required for tapered roller bearings is eliminated by extracting the pre-load function from the bearing assembly design. The cylindrical roller bearings and ball bearings are designed to operate without pre-load, removing the need for shimming operations while maintaining stable setup through proper bearing selection and arrangement.
3Force
If tapered rolling bearings are used in the bearing assembly, then the bearing assembly can support loads, but reliable pre-load over a wide temperature range and over time is difficult to maintain
Solution Approach 1:
The bearing assembly design changes the operating parameters by eliminating pre-load requirements. Cylindrical roller bearings and ball bearings are selected to operate without pre-load, making the system insensitive to temperature variations and time-dependent relaxation that plague pre-loaded tapered roller bearings, thereby maintaining reliable load support across wide temperature ranges and extended operational periods.
4Manufacturing precision
If the cylindrical roller bearing is arranged closer to the ring gear, then gear mesh deflection is minimized, but the bearing assembly arrangement becomes more specific
Solution Approach 1:
The bearing assembly employs local quality by positioning the cylindrical roller bearing specifically closer to the ring gear where radial loads are most critical for minimizing gear mesh deflection. The ball bearing is positioned on the opposite side to handle axial loads. This localized optimization of bearing positions addresses specific functional requirements without requiring complex overall rearrangement of the bearing 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 differential assembly effectively minimizes gear mesh deflection and skewness, maintaining parallel alignment of output shafts under radial loads, and reduces the complexity and cost associated with pre-load management.
Implementation Method 1
a bearing assembly supporting the carrier within the differential housing, the bearing assembly comprising a ball bearing and a cylindrical roller bearing
Implementation Method 2
the bearing assembly comprising a ball bearing and a cylindrical roller bearing arranged on opposite sides of the ring gear
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A differential assembly for distributing torque from an input shaft to first and second output shafts. The differential assembly comprises a ring gear configured to receive torque from the input shaft, a carrier attached to, and rotatable with, the ring gear, a differential housing, and a bearing assembly supporting the carrier within the differential housing. The bearing assembly comprises a ball bearing and a cylindrical roller bearing arranged on opposite sides of the ring gear. A distance between the cylindrical roller bearing and the ring gear is smaller than a distance between the ball bearing and the ring gear.