Differential Gear Housing Segmentation for Weight Reduction
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Solution Overview
Problem
Conventional differential gears are complex, heavy, and costly due to the need for stiff differential housings and rigid attachments, which complicates assembly and increases weight and manufacturing costs.
Innovation Solution
A differential gear design where the ring-shaped gear wheel is attached to the differential housing without a positive circumferential fit, using recesses for a form-fit driving pin, allowing the differential housing to be made lighter and more cost-effective as a thin-walled component, with a two-part housing and roller bearings for axial and radial support, eliminating the need for welding or screws and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the gear wheel is attached to the differential housing with a positive fit (welded or screwed connections), then the attachment is rigid and torsionally stiff, but the structure becomes complex, heavy, and costly
Solution Approach 1:
The differential housing is divided into two separate parts: the housing itself and the gear wheel. The gear wheel is no longer rigidly attached to the housing but instead engages with driving pins that are part of the housing structure. This segmentation eliminates the need for welded or screwed connections, simplifying the overall structure while maintaining functional integrity.
Solution Approach 2:
The attachment function is extracted from the housing structure. Instead of the housing directly supporting the gear wheel through rigid connections, the housing provides guiding surfaces and slots, while the driving pins serve as the actual torque transmission elements. This extraction simplifies the housing design and reduces structural complexity.
2Strength
If the differential housing is made stiff and robust to handle drive torques, then the housing can reliably transmit torques, but the weight increases
Solution Approach 1:
The torque transmission function is segmented from the housing structure. The housing no longer needs to be a monolithic stiff structure, but can be a thin-walled component. The driving pins and gear wheel recesses handle the torque transmission, allowing the housing to be significantly lighter while maintaining sufficient strength for its guiding and support functions.
Solution Approach 2:
The differential housing is designed as a thin-walled component made of steel or light metal. This thin-walled construction would normally be insufficient for torque transmission, but the innovative attachment system with driving pins and gear wheel recesses compensates for the reduced wall thickness, enabling the housing to be much lighter while still performing its support and guidance functions reliably.
3Ease of manufacture
If larger windows are provided in the differential housing for mounting planet gears and output gears, then assembly is facilitated, but the housing structure becomes more complex and requires larger components
Solution Approach 1:
The housing is divided into a cup-shaped section and a cover, with slots in the cup-shaped section that are open to the cover. This segmented design with open slots allows components to be inserted through the slots during assembly, then the cover is attached to enclose the differential gear. This approach facilitates assembly without requiring large windows in the final housing structure.
Solution Approach 2:
The slots are incorporated in the cup-shaped section before final assembly, allowing the driving pins and other components to be inserted through these pre-provided openings. The cover is then attached to complete the enclosure. This preliminary provision of access paths simplifies the assembly process without compromising the final housing structure.
Data Source
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AI summary
The invention relates to a differential gear, in particular for a motor vehicle, having a pinion-driven, ring-shaped gear wheel (12) arranged on a differential housing (14) that is rotatably mounted in a gearing housing by means of rolling bearings (32, 34) on both sides, wherein, in the differential housing (14), planetary gears (18) are mounted on at least one driving pin (16), said planetary gears meshing with axially parallel output gears (20) on output half-shafts (22). A construction that is advantageous in terms of structure and production is achieved in that the gear wheel (12) is fitted on the differential housing (14) in a peripheral direction without an interlocking connection and said gear wheel has recesses (12f) into which the at least one driving pin (16) projects in a peripheral direction in an interlocking manner.