Scroll Compressor Bearing Plate With Matched Thermal Expansion
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Solution Overview
Problem
The differential thermal expansion between the aluminium housing and steel bearing plate in positive-displacement machines leads to issues such as bearing clearance variation and preload during partial load operation, negatively affecting the service life of the bearing.
Innovation Solution
The use of a bearing plate made of steel with similar thermal expansion properties to the bearing, located completely within the housing, allows for a well-dimensioned press fit and functional separation, enhancing the service life of the bearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bearing plate is made of steel and the housing is made of aluminium, then corrosion protection and strength are improved, but differential thermal expansion causes bearing clearance variation and preload during operation
Solution Approach 1:
The housing is divided into two separate parts: the aluminium housing providing corrosion protection and the steel bearing plate providing structural support for the bearing. This segmentation allows each component to be optimized for its specific function while avoiding the thermal expansion compatibility issues that would arise from using a single material for both functions.
Solution Approach 2:
The bearing plate acts as an intermediary component between the aluminium housing and the bearing. By introducing this intermediate steel component, the design allows the bearing to be mounted on a steel surface (matching the bearing material) while the outer housing remains aluminium for corrosion protection. This intermediary structure resolves the thermal expansion mismatch problem.
2Reliability
If the bearing plate is made of steel with similar thermal expansion properties to the bearing, then bearing service life is improved, but material selection becomes more constrained
Solution Approach 1:
The structure is segmented into the aluminium housing and the steel bearing plate, allowing independent material selection for each component. The bearing plate can be made from steel with thermal expansion properties matched to the bearing, while the housing can be made from aluminium or other materials optimized for corrosion resistance and overall structural requirements.
3Ease of manufacture
If the bearing plate is located completely within the housing, then functional separation between housing and bearing plate is achieved, but device complexity increases
Solution Approach 1:
The housing assembly is segmented into the outer housing and the inner bearing plate, with each serving distinct functions. The bearing plate is positioned completely within the housing, creating a clear functional separation where the housing provides corrosion protection and overall structure, while the bearing plate provides the mounting surface for the bearing and anti-rotation mechanism.
Solution Approach 2:
The bearing plate is nested within the housing, creating a compact integrated structure. The anti-rotation mechanism is further nested by having its pins engage through the bearing plate into the displacement spiral. This nested arrangement achieves functional separation while maintaining a compact overall structure.
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 ensures even expansion of the bearing and bearing plate, improving the service life and reducing friction, vibrations, and noise emissions, while allowing for optimal material selection for corrosion protection and strength.
Implementation Method 1
the bearing plate and the bearing being made of materials whose coefficient of thermal expansion differs from one another by at most 20%, in particular by at most 10%, in particular by at most 5%
Data Source
AI summary
The invention relates to a positive-displacement machine according to the spiral principle, in particular a scroll compressor, said displacement machine comprising a housing which has a compressor housing and a drive housing, an orbiting displacement spiral and a counter spiral being located in the compressor housing and engaging into one another in such a way that variable compression chambers are formed between the displacement spiral and the counter spiral in order to receive and compress a working medium flowing through a working medium circuit, a drive shaft being located in the drive housing and being drivingly connected to the displacement spiral, a bearing plate being located between the drive housing and the compressor housing and carrying a bearing for the drive shaft, and an anti-rotation mechanism being provided between the bearing plate and the orbiting displacement spiral. The bearing plate is located completely inside the housing, the bearing plate and the bearing being made of materials having coefficients of thermal expansion which differ from one another by at most 20%, in particular by at most 10%, in particular by at most 5%.