Compressor Rotor Shaft Keyway Eccentricity
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Solution Overview
Problem
In compressors with standardized shaft main bodies and components across different capacities, the shift between the center of gravity and axial center of the rotary body increases, leading to oscillation and noise, particularly when using small-capacity motors with variable speed drives or low GWP refrigerants, as existing technologies fail to address the eccentricity caused by hollow keyways in the shaft main body.
Innovation Solution
A compressor design that includes a longer key and a spacer with a second through hole and third keyway, allowing the rotor to be fixed between the stepped portion and nut, thereby preventing interference and maintaining the center of gravity alignment, reducing oscillation and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the first through hole diameter is increased to facilitate rotor attachment and detachment, then the ease of operation is improved, but the center axis of the rotor shifts from the axial center of the shaft main body, increasing oscillation and noise
Solution Approach 1:
A key is introduced as an intermediary element between the shaft main body and the rotor. The key fits into a keyway on the shaft main body and a corresponding groove on the rotor, mechanically coupling the two components. This intermediary structure enables secure attachment and detachment while preventing relative displacement, thus eliminating the shift between rotor center axis and shaft axial center that would otherwise occur with loose fitting holes.
2Reliability
If the rotor is fixed between the stepped portion and nut, then the rotor is securely attached to the shaft main body, but the hollow part in the second keyway causes center of gravity shift, increasing oscillation and noise
Solution Approach 1:
A counterweight is provided on the shaft main body that is positioned to compensate for the mass distribution created by the hollow part in the second keyway. The counterweight has a mass and position specifically designed to balance the rotational assembly, counteracting the eccentricity caused by the hollow keyway region. This ensures that the center of gravity of the rotating parts coincides with the axis of rotation, eliminating oscillation and noise while maintaining secure rotor fixation between the stepped portion and nut.
Data Source
Figure 1~2(c)
Figure 3~4
Figure 5~7
AI summary
A compressor includes a key that is inserted in a first keyway of a rotor and a second keyway of a shaft main body, the key having a longer length than does the rotor, a spacer including a second through hole in which a part of the shaft main body that is between a stepped portion and a male screw portion is inserted, and a third keyway that is formed on an inner circumferential portion that corresponds to a wall surface portion that defines the second through hole, the key being inserted in the third keyway, the spacer being located at at least one of a part between the stepped portion of the shaft main body and the rotor or a part between the male screw portion of the shaft main body and the rotor, and a nut in which the male screw portion of the shaft main body is screwed, the nut sandwiching and fixing the rotor and the spacer with the stepped portion of the shaft main body.