Tilted Connecting Rod Axis Reduces Compressor Noise
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Solution Overview
Problem
Existing reciprocating piston compressors used in compressed air supply systems for vehicles, such as passenger cars, experience high noise levels due to structure-borne noise transmission through the connecting rod drive, which affects the acoustics and reliability of the compressor operation, especially in the passenger car sector where low noise levels are required.
Innovation Solution
The solution involves aligning the crankshaft journal and drive shaft coupling perpendicularly to the radially aligned cylinder axis, with the connecting rod axis tilted relative to the cylinder axis to reduce bearing clearance and prestress the connecting rod bearing, thereby minimizing noise emissions and improving acoustics by reducing free bearing play in the connecting rod bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the connecting rod axis is aligned parallel to the cylinder axis with standard bearing clearance, then the compressor structure is simple and easy to manufacture, but structure-borne noise transmission through the connecting rod drive increases significantly
Solution Approach 1:
The connecting rod axis is deliberately tilted at an angle of 5-15 degrees relative to the cylinder axis, creating an asymmetric configuration. This asymmetry shifts the bearing load distribution, reducing the impact forces and vibrations that cause structure-borne noise transmission through the connecting rod drive, while maintaining manufacturing feasibility through precise angular positioning.
Solution Approach 2:
The bearing clearance parameters are optimized by tilting the connecting rod axis, which changes the load distribution and contact pressure in the connecting rod bearing. This parameter modification reduces the bearing play and minimizes the generation of structure-borne noise during compressor operation.
2Object-generated harmful factors
If the connecting rod bearing clearance is reduced to minimize noise, then noise emission decreases, but the bearing preload increases and may affect reliability
Solution Approach 1:
The tilted connecting rod axis creates an asymmetric bearing clearance distribution, with different clearances in different directions. This asymmetric clearance pattern allows the bearing to maintain optimal contact under load while minimizing noise-generating play, balancing noise reduction with reliability requirements.
Solution Approach 2:
The connecting rod bearing is preloaded through the angular tilt configuration before operation begins. This preliminary action eliminates excessive bearing play that would cause noise, while the preload is carefully controlled to remain within safe limits that preserve bearing reliability and prevent premature failure.
Data Source
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Figure 3A~3B
AI summary
The invention relates to a reciprocating-piston machine, in particular a single-, two- or multi-stage piston compressor or a single-, two- or multi-cylinder compressing device, comprising: at least one cylinder and at least one piston, each piston being associated with one cylinder, wherein during operation the piston is deflected along a radially oriented cylinder axis in a cylinder displacement space of the cylinder, a crankshaft, which can be driven during operation and which has a crankshaft journal, which is arranged eccentric to a shaft axis of the crankshaft, and which has a drive shaft coupling, which is designed for coupling a drive shaft for driving the crankshaft, at least one connecting rod, which can be moved by means of the crankshaft journal, each connecting rod being designed to deflect one of the at least one piston and extending along a connecting rod axis. According to the invention, the crankshaft journal and/or the drive shaft coupling is oriented along an axially oriented shaft axis, which extends perpendicularly to the radially oriented cylinder axis, and the connecting rod axis of the connecting rod is tilted with respect to the radially oriented cylinder axis such that the bearing play of at least one connecting rod bearing is reduced.