Rotor Rivet Engagement Structure for Vibration-Stable PMSM Rotors
Solution Overview
Problem
Permanent magnet synchronous motors in electric compressors face structural instability due to thermal expansion differences in materials, leading to gaps and potential failure under vibration, especially in high-intensity applications like four-wheel drive vehicles.
Innovation Solution
A rotor assembly with an optimized engagement structure between the rotor rivet and balance weight, featuring a riveting process with a rod portion, head portion, and riveting portion, where the riveting portion is partially or fully filled in an expanded hole segment, enhancing the connection reliability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional riveting structures are used to connect balance weights to the rotor body, then the structure is simple and easy to manufacture, but under high-intensity vibration and temperature changes, gaps form between components and the riveting portion may break, leading to rotor failure
Solution Approach 1:
The riveting structure is segmented into three distinct portions: a rod portion that penetrates the rotor body, a head portion that secures the rivet in place, and a riveting portion that forms an expanded hole contour within the balance weight. This segmentation allows each portion to perform its specific function optimally, with the expanded hole contour providing enhanced mechanical interlocking to prevent gaps and breakage under vibration and thermal stress.
Solution Approach 2:
The riveting portion is formed by expanding the hole contour to create a composite structural interface between the rivet and balance weight. This expanded hole contour creates a mechanically interlocked composite structure that combines the rivet material with the balance weight material, enhancing the overall strength and reliability of the connection under high-intensity vibration and temperature variations.
2Adaptability or versatility
If materials with different thermal expansion coefficients are used for balance weights, end plates, and rotor cores, then each component can be optimized for its specific function, but temperature changes cause these components to expand or contract differently, creating gaps in fastening structures
Solution Approach 1:
The expanded hole contour in the riveting portion is specifically designed to accommodate thermal expansion differences between materials. The expanded geometry provides clearance and mechanical interlocking that maintains fastening structure integrity even when balance weights, end plates, and rotor cores expand or contract at different rates due to their different thermal expansion coefficients during temperature changes.
3Strength
If the riveting portion is fully filled in the expanded hole segment, then the connection strength is maximized, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The riveting portion may be partially or fully filled in the expanded hole segment, providing flexibility in manufacturing. Partial filling achieves sufficient connection strength for many applications while reducing manufacturing complexity and time, whereas full filling maximizes connection strength when required. This partial or excessive action approach allows optimization based on specific application requirements.
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
The solution significantly improves the structural stability and reliability of the rotor assembly, preventing riveting portion breakage and ensuring the electric compressor operates reliably under varying temperatures and vibrations.
Implementation Method 1
the riveting portion is at least partially filled in the second hole segment
Data Source
AI summary
A rotor assembly, a permanent magnet synchronous motor, an electric compressor, an air conditioning system, and a vehicle are provided. The rotor assembly includes a rotor body and rotor rivets. The rotor body includes a rotor core. End plates are arranged at two ends of the rotor core, respectively. Balance weights are disposed at a side of at least one of the end plates. The rotor rivets fix the rotor body into one piece. Each rotor rivet includes a rod portion, a head portion and a riveting portion. The head portion and the riveting portion are located at two ends of the rod portion. At least one of the balance weight is a first balance weight having a rivet hole. The rivet hole has a first hole segment configured to engage with the rod portion and a second hole segment configured to engage with the riveting portion.