Differential Gear Holder Structure for Compact Pinion Shaft Locking
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Solution Overview
Problem
Conventional differential gears require a space-increasing hole in the differential case to prevent relative rotation of the differential pinion shaft, leading to a larger axial size.
Innovation Solution
The differential gear design incorporates a holder between the pinion gears with a bulging portion and a flat surface that contacts the side gears, allowing the differential pinion shaft to be non-rotatable relative to the case without the need for a fixing pin hole, thereby reducing the axial size of the differential case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hole is formed in the differential case to insert a fixing pin to prevent relative rotation of the differential pinion shaft, then the non-rotatability of the pinion shaft is achieved, but the axial size of the differential case increases
Solution Approach 1:
The invention transitions from preventing rotation through axial positioning (using a hole and fixing pin in the axial direction) to preventing rotation through radial positioning (using a flat surface perpendicular to the rotation axis that contacts the side gear). This dimensional change in the restraining mechanism eliminates the need for axial space while achieving the same rotational constraint.
Solution Approach 2:
The invention extracts the rotational constraint function from the differential case structure (which required a hole) and relocates it to the differential pinion shaft itself (through the bulging portion with flat surface). This extraction allows the case to be simplified and reduced in size while the shaft assumes the constraint function.
2Reliability
If a fixing pin is inserted through the differential case and pinion shaft to restrict relative rotation, then the pinion shaft non-rotatability is ensured, but the device complexity increases due to additional components and assembly steps
Solution Approach 1:
The invention merges the rotational constraint function into the differential pinion shaft structure itself through the bulging portion with flat surface. This eliminates the need for separate fixing pins and holes in the case, reducing the number of components and simplifying the overall structure while maintaining the same functional outcome.
Solution Approach 2:
The differential pinion shaft structure itself (through its bulging portion with flat surface) provides the rotational constraint function, rather than requiring external constraint mechanisms. The shaft's own geometry enables it to prevent relative rotation with the side gear, making the system self-constraining and reducing dependency on additional components.
Data Source
AI summary
A differential gear includes a holder which is provided between first and second pinion gears in a differential case and through which a differential pinion shaft is inserted. An insertion hole is radially formed in the differential pinion shaft. The holder is formed with a fixing hole facing the insertion hole when the differential pinion shaft is inserted through the holder. Due to insertion of a fixing pin through the fixing hole and the insertion hole, the differential pinion shaft and the holder are relatively non-rotatable. Due to the holder being held between first and second side gears, relative rotation of the holder with respect to the differential case is restricted, and the differential pinion shaft is non-rotatable relative to the differential case.