Zero-Clearance Bolted Joint for Ring Gear Assembly
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Solution Overview
Problem
Bolted joints used to join a ring gear to a differential case are prone to slippage due to insufficient tension, leading to bolts backing out, and existing designs face challenges with alignment tolerance and load-bearing capabilities under substantial loads.
Innovation Solution
A zero-clearance bolted joint is created using bolts with tapered shoulders to cold-form deformable sleeves, providing a secure fit by dilating the sleeves to contact internal walls of the differential case, thereby minimizing slippage and accommodating alignment variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bolts are used to join ring gear to differential case, then the joint can be assembled, but the bolts cannot produce enough tension to prevent gear slippage under substantial loads
Solution Approach 1:
The bolt design changes the physical parameters of the joint by incorporating a tapered shoulder that cold-forms the sleeve material, transforming the joint from a clearance fit to a zero-clearance interference fit. This parameter change in the sleeve's dimensional state creates substantial friction and mechanical interlocking that prevents slippage under load.
Solution Approach 2:
The deformable sleeve acts as an intermediary element between the bolt and the hole. The sleeve is deformed by the tapered shoulder to create a friction fit that transfers and distributes the bolt tension across a larger area, enabling the joint to withstand substantial loads without slippage.
2Manufacturing precision
If through holes with tight tolerances are used for precise alignment, then alignment accuracy is improved, but manufacturing complexity and cost increase due to stringent tolerance requirements
Solution Approach 1:
The deformable sleeve allows the hole diameter parameter to change during assembly. The sleeve is inserted in a relaxed state, then deformed by the tapered shoulder to create a friction fit. This parameter change enables the use of larger tolerance zones for hole positioning while still achieving a precise zero-clearance fit after deformation.
Solution Approach 2:
The sleeve is prepared in advance with a diameter that allows easy insertion into the hole with tolerances. The precise alignment is achieved not through tight hole tolerances but through the preliminary deformation of the sleeve by the tapered shoulder, which creates the zero-clearance condition after assembly.
3Reliability
If bolts are installed with high tension to prevent slippage, then gear slippage is reduced, but the bolts tend to back out due to excessive stress
Solution Approach 1:
The joint mechanism changes from direct bolt-to-hole contact to bolt-to-sleeve-to-hole contact. The sleeve deformation creates a friction fit that provides substantial slippage resistance through friction and mechanical interlocking, allowing the bolt tension to be lower while still preventing slippage. This reduces the tendency for bolts to back out.
Solution Approach 2:
The deformable sleeve serves as an intermediary that provides a compliant interface between the bolt and the rigid hole. The sleeve's deformation absorbs some of the stress and creates a friction-based connection that prevents slippage without requiring excessively high bolt tension that would cause bolt backout.
4Reliability
If a zero-clearance fit is achieved through sleeve deformation, then gear slippage is minimized, but the assembly process becomes more complex
Solution Approach 1:
The sleeve is prepared in advance with specific dimensional properties that enable easy insertion. The zero-clearance condition is achieved through the preliminary deformation action of the tapered shoulder during normal assembly, rather than requiring complex post-assembly operations. The assembly process remains relatively simple while achieving the zero-clearance fit.
Solution Approach 2:
The tapered shoulder on the bolt automatically deforms the sleeve to create the zero-clearance fit during the normal assembly process. The system is self-configuring - the act of inserting and tightening the bolt itself creates the interference fit condition without requiring additional steps, tools, or operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces gear slippage and prevents bolt backout even under substantial loads, ensuring a secure and forgiving joint for repeated cycles by creating a 'zero-clearance' fit through the deformation of sleeves by tapered shoulders.
Implementation Method 1
using a bolt having a tapered shoulder to cold form a deformable sleeve in order to provide a 'zero-clearance' fit
Implementation Method 2
tapered shoulders on the bolts dilate deformable sleeves until the outer diameters of the sleeves contact internal walls of through holes
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A bolted joint which is formed by using a bolt (20, 20a) having a tapered shoulder (44, 21a) to cold form a deformable sleeve (46, 46a) in order to provide a "zero-clearance" fit. Specifically, preferably a plurality of bolted joints are used to join a ring gear (42) to a differential case (58). As the bolts are installed into the differential case (58) and ring gear (42), tapered shoulders (44, 21a) on the bolts (20) dilate deformable sleeves (46, 46a) until outer diameters of the sleeves (46, 46a) contact internal walls of through holes (56) in the differential case (58).