Compact Differential Device Radial Pinion Support
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Solution Overview
Problem
Conventional differential devices are structurally wide in the axial direction of output shafts, making them difficult to incorporate into transmission systems with layout restrictions and increasing the overall size of the transmission system.
Innovation Solution
The differential device design includes side gears with shaft portions connected to output shafts and intermediate wall portions that are wider radially than the pinion, and a cover portion with a boss and plate-shaped side wall, allowing for a larger diameter side gear with more teeth and reduced thickness, which decreases the axial width while maintaining torque transmission strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the side gear diameter is increased to have more teeth than the pinion, then the torque transmission capability is improved, but the axial width of the differential device increases
Solution Approach 1:
The patent repositions the pinion support portion from the axial direction to the radial direction of the input member. The pinion is supported at the radial end face of the input member rather than along the axial direction, allowing the side gears to have larger diameters with more teeth while maintaining a compact axial width. This dimensional reconfiguration enables the side gear outer peripheral portions to extend radially outward while the overall axial width remains controlled by the input member's axial dimension.
2Strength
If the side gear diameter is increased to have more teeth than the pinion, then the load distribution is improved, but the overall size of the transmission system increases
Solution Approach 1:
The invention shifts the pinion support arrangement to the radial direction, enabling side gears with larger diameters and more teeth for better load distribution, while the axial width is constrained by the input member's compact axial dimension. This allows improved load distribution without proportionally increasing the overall transmission system volume.
3Strength
If the conventional differential device structure is used, then the torque transmission is maintained, but the device is difficult to incorporate into transmission systems with layout restrictions
Solution Approach 1:
The patent reconfigures the pinion support portion to be located at the radial end face of the input member, with the pinion shaft extending radially rather than axially. This dimensional change creates a compact axial profile that allows the differential device to be integrated into transmission systems with tight axial space constraints, while still maintaining full torque transmission capability through the radial pinion-side gear arrangement.
Data Source
AI summary
In a differential device, paired side gears include shaft portions and intermediate wall portions formed in a flat plate shape intersecting an axis of the output shafts, the intermediate wall portions integrally connecting the shaft portions to toothing portions of the side gears separated outward from the shaft portions in a radial direction of an input member, respectively. Each of the intermediate wall portions is formed with a width in the radial direction which is longer than a maximum diameter of a pinion. A cover portion includes a boss portion and a side wall portion connected to the boss portion and having an outer side surface as a surface orthogonal to the axis of the output shafts. A back surface of at least one of the intermediate wall portion and the toothing portion is supported on an inner side surface of the side wall portion.