Bevel Gear Axial Size Reduction via Opposite-Surface Clutch
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Solution Overview
Problem
Existing bevel gears in lock-up differentials are made in a massive form to bear complex stresses, resulting in a heavier and larger differential device due to the need to accommodate both gear and clutch teeth, which increases axial size and weight.
Innovation Solution
A bevel gear design featuring gear teeth with top lands and clutch teeth with bottom lands aligned in a line parallel to the axis, reducing twisting stress and allowing for a thinner, lighter construction by minimizing the need for thick sections to handle stress, and a differential device with a controllable clutch mechanism to restrict differential motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bevel gear is made in a massive form to bear complex stresses from both gear set and locking means, then the strength and reliability are improved, but the weight and axial size of the differential device increase
Solution Approach 1:
The patent positions the clutch teeth on the opposite surface (back side) of the bevel gear rather than on the same surface as the gear teeth. This spatial arrangement in another dimension allows the stress paths from gear meshing and clutch engagement to be more separated, reducing the need for excessive material thickness to handle combined stresses, thereby reducing weight while maintaining strength.
Solution Approach 2:
The patent applies different local structures to different surfaces of the bevel gear: gear teeth on the pitch surface for torque transmission, and clutch teeth on the opposite surface for locking function. This local differentiation allows each surface to be optimized for its specific function rather than requiring the entire gear to be massively constructed to handle all possible stresses.
2Strength
If the bevel gear is made in a massive form to bear complex stresses from both gear set and locking means, then the strength and reliability are improved, but the axial size of the differential device increases
Solution Approach 1:
By placing clutch teeth on the opposite surface of the bevel gear (another dimension relative to the gear teeth location), the patent enables a more compact axial arrangement. The differential device no longer requires excessive axial thickness to accommodate both gear and clutch functions in the same radial plane, thus reducing overall axial size while maintaining structural strength.
Solution Approach 2:
The bevel gear is segmented into two distinct functional surfaces: the pitch surface with gear teeth for differential motion, and the opposite surface with clutch teeth for locking function. This segmentation allows each surface to be thinner and optimized for its specific purpose, reducing the need for a single massive structure to handle all functions.
3Reliability
If the bevel gear is made in a massive form to bear complex stresses, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The bevel gear is designed as a multi-functional component that simultaneously serves as both a gear element (transmitting torque through gear teeth on the pitch surface) and a clutch element (engaging locking means through clutch teeth on the opposite surface). This universality eliminates the need for separate massive structures for each function, reducing overall device complexity while maintaining reliability through integrated stress handling.
Data Source
AI summary
A bevel gear used in a differential device for a vehicle is comprised of: a body having an axis, a conical pitch surface around the axis, an opposite surface opposed to the conical pitch surface, and a side surface around the axis; gear teeth formed on the pitch surface, each of the gear teeth having a top land projecting from the pitch surface; and clutch teeth formed on the opposite surface, each of the clutch teeth having a bottom land standing back from the opposite surface, each of the bottom lands of the clutch teeth being aligned with any of the top lands of the gear teeth in a line parallel to the axis.