Differential Gear Assembly Using Dummy Shaft for Pinion Alignment
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Solution Overview
Problem
Conventional differential gear set assembling devices face challenges with poor insertion of pinion shafts due to loads from side gears, leading to positional displacement and potential damage during assembly, as existing solutions to mitigate these issues are complex and difficult to implement within the limited space of the device.
Innovation Solution
A differential gear set assembling method and device that utilizes guide and projecting portions to reduce loads on pinions by pivoting and pressing the side gears, allowing for coaxial alignment and smooth insertion of the pinion shaft, with features like spherical guide surfaces and abutment portions to manage biasing forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pinion shaft is inserted while the side gears are biased by coned disc springs, then the differential gear set can be assembled, but the pinions receive loads causing positional displacement and inclination of pinion shaft holes leading to poor insertion
Solution Approach 1:
The patent applies preliminary action by inserting a dummy shaft before the pinion shaft to temporarily hold the pinions in position. This preliminary component prevents the pinions from moving under load during the subsequent pinion shaft insertion, ensuring proper alignment of the pinion shaft holes. The dummy shaft is removed after the pinion shaft is successfully inserted, having served its temporary supportive function.
Solution Approach 2:
The dummy shaft acts as an intermediary component between the pinions and the pinion shaft. It mediates the assembly process by providing temporary support to the pinions, preventing them from experiencing harmful loads that would cause misalignment. This intermediary element facilitates the successful insertion of the final pinion shaft without compromising alignment precision.
2Manufacturing precision
If a device for reducing loads from side gears to pinions is provided separately, then poor insertion of pinion shaft can be reduced, but the device complexity increases and space requirements are not met
Solution Approach 1:
The patent merges the load reduction function with the existing assembling device structure by integrating the dummy shaft insertion mechanism into the conventional assembly process. Rather than adding a separate complex device, the solution combines the temporary support function with the pinion shaft insertion operation itself, using the same operational sequence to achieve both positioning and final assembly.
Solution Approach 2:
The patent changes the temporal parameter of the support mechanism by using a temporary dummy shaft that is present only during the critical insertion phase. This parameter change allows the system to have load-reducing capability only when needed, rather than maintaining a permanent complex structure. The dummy shaft is inserted, serves its function, and then removed, changing the system state from having load reduction capability to not having it.
Data Source
AI summary
A differential gear set assembling method includes: a pivoting step of closing openings by guide portion and pivoting a pair of pinions between a pair of side gears; and an insertion step of inserting a pinion shaft into a pair of case shaft holes and a pair of pinion shaft holes from outside the differential case. The pivoting step is performed in a state where projecting portions are buried in the guide portions. The insertion step is performed in a state where the projecting portions are projected from the guide portions toward the pair of side gears, and the pair of side gears are pressed by the projecting portions so as to apply loads against biasing forces of coned disc springs to the pair of side gears.