CVJ Integral Inner Race Weld Attachment Sealing
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Solution Overview
Problem
Existing constant velocity joints with integral inner joint parts face challenges in assembly and sealing due to hardening processes, which restrict the elasticity of sealing components and increase manufacturing complexity, especially in longitudinal shafts.
Innovation Solution
A double-sealed constant velocity joint with an integral inner race featuring a weld attachment with an enlarged diameter to accommodate an adapter, allowing for pre-assembly of the sealing element before hardening, and using a tubular adapter with a welding attachment for secure connection, replacing complex assembly steps with a cheaper welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the inner joint part is hardened to increase surface hardness and wear resistance, then the ball raceways gain high wear resistance, but the sealing bellows cannot be installed before hardening and must be pulled over the hardened surface, which exceeds the bellows' elasticity limits
Solution Approach 1:
The inner joint part is divided into two distinct sections: a hardened ball raceway section for wear resistance and a softer weld attachment section for sealing element installation. This segmentation allows each section to have optimized properties - the ball raceway section undergoes hardening treatment while the weld attachment section remains softer to accommodate the bellows installation without exceeding elasticity limits.
Solution Approach 2:
Different material properties are applied to different locations of the inner joint part. The ball raceway area receives hardening treatment to achieve high surface hardness and wear resistance, while the weld attachment area maintains lower hardness to allow bellows installation. This local differentiation resolves the contradiction between needing hard surfaces for wear resistance and soft surfaces for sealing element installation.
2Reliability
If the inner joint part is hardened before sealing element installation, then wear resistance is improved, but the assembly complexity increases due to additional hardening process steps and restricted installation options
Solution Approach 1:
The manufacturing process is segmented into distinct phases: first, the ball raceway section is hardened to achieve wear resistance; second, the weld attachment section is prepared with lower hardness; third, the sealing bellows are installed on the softer weld attachment section. This process segmentation simplifies manufacturing by allowing parallel preparation of different sections with different material properties.
Solution Approach 2:
The hardening treatment is applied locally only to the ball raceway section rather than the entire inner joint part. This localized hardening reduces the overall manufacturing complexity by limiting the heat treatment scope, while the weld attachment section remains softer and more ductile, facilitating easier sealing element installation without requiring complex post-hardening assembly procedures.
3Weight of moving object
If the inner joint part diameter is reduced to minimize material usage, then weight is reduced, but the sealing bellows cannot be installed over the narrowest section due to insufficient elasticity
Solution Approach 1:
The inner joint part is segmented into a narrow ball raceway section for minimal weight and a larger-diameter weld attachment section for sealing element installation. This segmentation allows the critical sealing area to have sufficient diameter for bellows installation while the ball raceway section maintains minimal diameter for weight reduction.
Solution Approach 2:
Different diameters are implemented at different locations of the inner joint part. The ball raceway section has a smaller diameter to minimize material usage and weight, while the weld attachment section has a larger diameter to provide the necessary elasticity and space for bellows installation. This local diameter variation resolves the contradiction between weight minimization and sealing element installability.
4Adaptability or versatility
If conventional multi-part connections are used for shaft-hub connection, then adaptability to different shaft designs is achieved, but assembly effort and manufacturing complexity increase
Solution Approach 1:
The adapter and the inner joint part are merged into a single integral component through welding. This merging eliminates the need for separate adapter manufacturing, pressing operations, and safety ring assembly, significantly reducing assembly effort and manufacturing complexity while maintaining the adaptability benefits of the adapter design for different shaft configurations.
Solution Approach 2:
The weld attachment section of the inner joint part serves multiple functions: it provides a connection interface for the adapter, accommodates the sealing bellows, and enables torque transmission. This multi-functionality consolidates what would otherwise require multiple separate components, improving productivity while maintaining adaptability to different shaft designs through the adapter interface.
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 provides a ready-to-use, modular, and cost-effective constant velocity joint with enhanced wear resistance and torque transmission, reducing assembly efforts and component complexity while ensuring tightness and modularity.
Implementation Method 1
the integral inner joint part is hardened
Implementation Method 2
an adapter (16) is welded onto the weld attachment (15)
Data Source
Figure 1a~1b
Figure 2
AI summary
The invention relates to a constant velocity joint with an integral inner joint part, consisting of an outer joint part (1) with inner ball tracks, an inner joint part (2) with outer ball tracks associated with the inner ball tracks, and balls (4) held in a ball cage (3). The outer joint part (1) is connectable to a connecting part and sealed on the side facing this connecting part with a sealing cap (7). The inner joint part (2) is designed as an integral inner joint part (6) that is permanently and non-destructively connected to a shaft section (5) and is sealed on this side to the outer joint part (1) by means of a flexible sealing element (10). According to the invention, the integral inner joint part (6) is provided at its free end, which projects from the sealing element (10), with a welded end (15) for receiving an adapter (16).The outer diameter of this weld attachment (15) is larger than the smallest outer diameter of the integral inner joint part (6). The integral inner joint part (6) is hardened. According to the inventive method, the sealing element (10) is fitted over the free end of the integral inner joint part (6) and connected to the outer joint part (1). Finally, the adapter (16) is welded to the integral inner joint part (6) in the area of the weld attachment (15).