Coreless Seal Thermal Shrinkage Compensation in Roller Bearings
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Solution Overview
Problem
Coreless seals in shell-type roller bearings fail to maintain high sealing properties at low temperatures due to thermal shrinkage, leading to gaps and increased leakage.
Innovation Solution
A coreless seal with an outer diameter dimension obtained by adding interference for thermal shrinkage, ensuring the seal's outer diameter remains larger than the inner diameter surface of the outer member, preventing gaps and maintaining nipping pressure even at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a coreless seal is used in a shell-type roller bearing, then the seal can be easily removed after assembly and cost is reduced, but the seal fails to maintain high sealing properties at low temperatures due to thermal shrinkage
Solution Approach 1:
The seal outer diameter is designed with preliminary compensation for thermal shrinkage by adding an interference dimension. This preliminary action ensures that even after thermal contraction at low temperatures, the seal maintains sufficient contact pressure with the outer member inner diameter surface to prevent leakage.
Solution Approach 2:
The seal dimension parameter is changed by adding interference for thermal shrinkage to the outer diameter. This parameter modification allows the seal to compensate for thermal contraction effects and maintain sealing performance across temperature variations without requiring a cored bar structure.
2Reliability
If a cored seal with a metal cored bar is used, then rigidity is ensured and thermal shrinkage is reduced at low temperature, but the seal cannot be easily removed after assembly and manufacturing cost increases
Solution Approach 1:
The metal cored bar is extracted from the seal structure. By removing this rigid reinforcing element, the seal becomes easier to manufacture and remove, while the sealing function is maintained through dimensional interference design that compensates for thermal shrinkage without requiring additional structural components.
Solution Approach 2:
Instead of using a cored bar to resist thermal shrinkage, the solution changes the seal outer diameter parameter by adding interference dimension. This parameter modification provides the necessary thermal compensation function without the complexity of a multi-component structure.
3Ease of manufacture
If the seal outer diameter is designed without interference compensation, then assembly is simpler, but gaps form at low temperature leading to increased leakage
Solution Approach 1:
The interference dimension is preliminarily built into the seal outer diameter design. This preliminary action creates a dimensional buffer that compensates for thermal shrinkage, preventing gap formation and leakage at low temperatures while maintaining assembly simplicity.
Solution Approach 2:
The interference dimension provides preliminary anti-action against thermal shrinkage. By designing the seal with a larger initial outer diameter, the design anticipates and counteracts the harmful thermal contraction effect before it causes leakage.
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 coreless seal effectively prevents leakage between the roller bearing and the throttle shaft at low temperatures by ensuring the outer diameter surface nips the inner diameter surface with appropriate pressure, maintaining high sealing properties.
Implementation Method 1
an outer diameter of the coreless seal is a dimension obtained by adding interference for an amount of thermal shrinkage
Implementation Method 2
its outer diameter surface nips the inner diameter surface with appropriate pressure
Data Source
Figure 1
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Figure 4~5
AI summary
A coreless seal 11 for being assembled in a shell-type roller bearing provided in a shell-type roller bearing comprises an elastic annular member 12. An outer diameter B of the coreless seal 11 for being assembled in the shell-type roller bearing is a dimension provided by adding interference 2A for an amount of thermal shrinkage to an inner diameter C of a shell-type outer ring. Since the annular member 12 shrinks in a direction shown by an arrow W at low temperature, the outer diameter of the coreless seal 11 for being assembled in the shell-type roller bearing is reduced from B to B'. However, since the outer diameter B is provided with the dimension A obtained by adding interference for an amount of thermal shrinkage, the coreless seal 11 for being assembled in the shell-type roller bearing has interference A' in its outer diameter B' even after the shrinkage.