Electric Compressor Rotor Weight Member for Vibration Control
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Solution Overview
Problem
Electric compressors using rare-earth magnets in refrigeration and air conditioning systems face inefficiencies due to reduced rotor inertia, leading to increased vibration, noise, and oil loss from mixing of lubricant oil and refrigerant gas, which affects performance and reliability.
Innovation Solution
A ring-shaped weight member with a flat outer end surface is positioned close to the compression mechanism on the rotor, acting as a rotary inertia body to reduce angular velocity changes and whirling, while being nonmagnetic near the rotor and magnetic elsewhere to prevent flux leakage, and is integrated with rivets or bolts to prevent oil mixing, with an asymmetrical design and specific material distribution for balance and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rare-earth magnet is used to increase magnetic force, then the output is improved, but the rotor weight is reduced and inertia force in rotation is decreased
Solution Approach 1:
A weight member is added to the rotor to compensate for the reduced inertia force caused by using a rare-earth magnet. This counterweight restores the necessary rotational inertia to maintain stable angular velocity during compression strokes, resolving the contradiction between using lightweight rare-earth magnets for higher output and maintaining sufficient rotor inertia.
2Weight of moving object
If the rotor weight is reduced, then the size and weight of the electric motor are reduced, but the change in angular velocity due to gas compression torque becomes greater
Solution Approach 1:
The weight member acts as a counterweight that increases the overall rotational inertia of the rotor assembly. This compensates for the reduced inertia from using lightweight rare-earth magnets, thereby stabilizing angular velocity during compression strokes while maintaining the benefits of reduced motor weight and size.
3Stability of the object's composition
If a weight member is provided on the rotor, then the change in angular velocity is reduced, but whirling is caused in proportional to the weight of the weight member and the distance between the compression mechanism and the electric motor
Solution Approach 1:
The weight member is positioned locally at the compression mechanism side end surface of the rotor, close to the compression mechanism. This localized placement minimizes the distance factor in the whirling equation while still providing sufficient inertia to stabilize angular velocity, thereby reducing the harmful whirling effect.
4Strength
If protrusions are provided on the weight member for fixing, then the weight member can be securely attached, but the protrusion mixes lubricant oil and refrigerant gas leading to power loss and oil loss
Solution Approach 1:
The protrusions that cause oil mixing are removed from the weight member design. Instead, the weight member is fixed using countersunk portions and swaging portions of rivets that do not protrude beyond the outer peripheral surface, eliminating the source of oil-refrigerant mixing while maintaining secure attachment.
5Object-generated harmful factors
If the weight member is placed close to the compression mechanism, then whirling is reduced, but the distance between the compression mechanism and the electric motor is reduced
Solution Approach 1:
The weight member is positioned locally at the compression mechanism side end surface of the rotor, maximizing its proximity to the compression mechanism. This localized placement minimizes the distance factor in the whirling equation, thereby reducing whirling while the overall motor structure maintains appropriate spacing between the compression mechanism and electric motor components.
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 configuration enhances compressor efficiency, reduces vibration and noise, and minimizes oil loss, thereby improving lubrication and heat exchange performance, while maintaining cost-effectiveness by using inexpensive materials effectively.
Implementation Method 1
the inertia force of the mass body is used to reduce a change in the angular velocity of the motor rotor
Implementation Method 2
the end portion of the weight member close to the rotor is formed of the nonmagnetic body, and the outer end portion of the weight member is formed of the magnetic body
Data Source
Figure 1
Figure 2
AI summary
An electric compressor 1 includes an electric motor 3, a rotary drive shaft 9 joined to a rotor 6 of the electric motor 3, a compression mechanism 4 including, at least on one end side of the rotary drive shaft 9, bearing members 10, 11 configured to support the rotary drive shaft 9 and driven through the rotary drive shaft 9, and a weight member 25 as a rotary inertia body provided at least on the end surface of the rotor 6 close to the compression mechanism 4 or each end surface of the rotor 6. The weight member 25 provided on the end surface of the rotor 6 close to the compression mechanism 4 is a ring-shaped weight member 25 hung over the outer periphery of a boss portion 10A of the bearing member 10 forming the compression mechanism 4 and having a flat outer end surface.