Scroll Compressor Knock Pin Fixing Eliminates Centering
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Solution Overview
Problem
Existing scroll compressor assembly methods require complex centering processes, leading to increased manufacturing costs, material costs, and reduced precision due to the need for precise machining and potential cutter breakage, resulting in misalignment and performance deterioration.
Innovation Solution
A scroll compressor design featuring a fixed scroll with a cylindrical portion and flanges, and a frame with corresponding inner circumferential surfaces and holes, utilizing a knock pin for rotational positioning and eliminating the need for fastening bolts, allowing for high-precision assembly without centering the fixed and orbiting scrolls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fastening bolt is used to fix the fixed scroll to the frame, then the center positions can be adjusted automatically by rotation shaft rotation, but the assembling time becomes longer and the number of parts increases
Solution Approach 1:
The invention extracts and eliminates the fastening bolt from the assembly system. Instead of using a bolt to fix the fixed scroll to the frame, the patent uses a integrated positioning structure where the rotation shaft itself provides both rotational drive and centering function, removing the separate fastening component and simplifying the assembly process
Solution Approach 2:
The rotation shaft is given multiple functions: it serves both as the driving element for orbital motion and as the centering mechanism. By making the rotation shaft universal, the patent eliminates the need for separate centering adjustment mechanisms, thereby reducing assembly time and part count while maintaining automatic centering capability
2Strength
If a fastening bolt is used to fix the fixed scroll to the frame, then the connection is secure, but the manufacturing cost and material cost increase
Solution Approach 1:
The fastening bolt is completely removed from the system. The patent replaces the bolt-based connection with an integrated positioning structure where the rotation shaft and frame work together to provide both structural support and centering, eliminating the need for additional fastening components
Solution Approach 2:
The invention merges the centering function and the fastening function into a single integrated structure. The rotation shaft and frame are designed to work together as a unified system that provides both rotational support and precise centering, eliminating the need for separate fastening parts
3Manufacturing precision
If precise machining of the arcuate surface and circumferential end is performed, then the coaxiality and rotational positional precision are improved, but the cutter is broken down and piecework can be left uncut
Solution Approach 1:
Instead of relying on precise machining of complex arcuate surfaces, the invention inverts the approach by using simple cylindrical surfaces and flat surfaces that are much easier to machine. The positioning is achieved through the geometry of the rotation shaft and frame rather than through complex curved surfaces, thereby reducing machining complexity and cutter wear
Solution Approach 2:
The invention changes the geometric parameters of the positioning surfaces from complex arcuate shapes to simple cylindrical and flat surfaces. This parameter change makes the machining process much more reliable and reduces the likelihood of cutter breakdown while maintaining the required positioning precision
4Manufacturing precision
If the inner circumferential surface of the crankcase tower is machined, then the positioning is improved, but chattering occurs and processing accuracy is lowered
Solution Approach 1:
Instead of machining the inner circumferential surface of the crankcase tower which is prone to chattering, the invention inverts the approach by using the outer cylindrical surface of the rotation shaft as the primary positioning element. This surface is much more stable to machine and does not suffer from chattering issues
Solution Approach 2:
The invention converts the potential harm of chattering during machining into a benefit by avoiding the problematic area altogether. By positioning the machining operations on the rotation shaft rather than on the crankcase tower, the patent eliminates chattering while still achieving precise positioning through the cylindrical fit
Data Source
AI summary
A centering process and fastening bolt are not required for assembling a fixed scroll and an orbiting scroll of a scroll compressor that includes a hermetically sealed container and a compression mechanism. The fixed scroll includes a cylindrical portion formed in a circumferential direction on an outer circumferential side of the fixed wrap, a flange provided in the circumferential direction further outside of the cylindrical portion, and a first hole provided in the flange in an axial direction. The frame includes an inner circumferential surface, a flange provided in the circumferential direction further outside of the inner circumferential surface, and a second hole in the axial direction which is provided in a position of the flange opposite to the first hole. A knock pin is inserted in the first and second holes to prevent the frame and the fixed scroll from being displaced in the rotational direction.