Multi-part Piston Compressor Mass Balance
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Solution Overview
Problem
Piston compressors face challenges in achieving mass balance between pistons of varying diameters, leading to imbalance and vibration when driven by a common crankshaft, due to differences in thermal expansion coefficients between pistons and cylinders made of different materials.
Innovation Solution
A piston compressor design featuring a one-part piston with an aluminum piston skirt and steel piston crown, and a multi-part piston with an aluminum skirt and steel piston head, allowing for mass balancing and thermal expansion matching with the cylinder, while using screws for a secure connection between the parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a smaller-diameter piston is made from gray cast iron to balance mass, then mass balance is improved, but thermal expansion mismatch causes play and sealing problems
Solution Approach 1:
The piston is divided into two separate parts: a piston skirt made of aluminum and a piston crown made of steel. This segmentation allows each part to be made from materials optimized for its specific function - the aluminum skirt matches the cylinder's thermal expansion characteristics while the steel crown provides the necessary mass for balancing.
Solution Approach 2:
The piston combines two different materials (aluminum and steel) into a single composite structure. The aluminum piston skirt provides thermal expansion compatibility with the aluminum cylinder, while the steel piston crown adds the required weight for mass balance, creating a multi-material solution that addresses both thermal and mass balance requirements simultaneously.
2Productivity
If a smaller-diameter piston is used to reduce swept volume, then compression efficiency is improved, but mass imbalance increases vibration
Solution Approach 1:
By using a composite piston structure with aluminum skirt and steel crown, the smaller piston achieves the necessary mass through the high-density steel material in the crown section, enabling mass balance with larger pistons while maintaining the swept volume reduction benefits for compression efficiency.
Solution Approach 2:
The invention changes the material composition parameter of the piston, using a combination of materials with different densities (aluminum and steel) to adjust the overall mass of the smaller piston, thereby achieving mass balance without altering the piston's dimensional parameters that determine swept volume.
3Stability of the object's composition
If the piston skirt is made of aluminum to match thermal expansion, then thermal compatibility is improved, but piston mass decreases
Solution Approach 1:
The piston is segmented into an aluminum skirt portion for thermal compatibility and a steel crown portion for mass contribution, allowing each segment to fulfill its specific requirement without compromise.
Solution Approach 2:
Different parts of the piston have different material qualities optimized for their local requirements: the skirt region uses aluminum for thermal expansion matching with the cylinder, while the crown region uses steel for mass balancing, creating local optimization throughout the component.
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
This design achieves mass balance between pistons, reduces vibration, and prevents excessive play between the piston and cylinder by optimizing material selection and thermal expansion properties, ensuring efficient operation and sealing.
Implementation Method 1
The piston skirt can be selected in its material so that it in terms of its thermal Properties are optimized and in particular adapted to the cylinder, so that it can be designed in such a way that when it comes to heating, this does not lead to excessive play between the piston and the cylinder.
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a piston compressor with one or more pistons (10), wherein at least one piston (10) is composed as a multi-part piston from at least a first (12) and a second part (14) which are made of different materials.