Stator Slot Impregnation With Radial Compaction to Eliminate Voids
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Solution Overview
Problem
Existing impregnation methods for dynamo-electric machine stators result in cavities and air inclusions, reducing efficiency, dielectric strength, and heat dissipation, while being time-consuming and costly, and are difficult to optimize for various motor types.
Innovation Solution
A method involving radial pressure application during the gelation phase of impregnation, using a lamellar press or rollers to compact the winding system, ensuring even resin distribution and elimination of voids, combined with a double-layered cover slide design for improved resin flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum potting or immersion impregnation is used to eliminate cavities, then dielectric strength is improved, but manufacturing time and cost increase significantly
Solution Approach 1:
The slot insulation is pre-impregnated with resin before the winding is inserted into the slot. This preliminary impregnation ensures that the insulation material is already saturated with resin, creating a resin-rich environment that prevents air inclusion when the winding is subsequently inserted and compacted. This eliminates the need for time-consuming post-assembly vacuum potting or immersion impregnation processes.
Solution Approach 2:
The impregnation process is segmented into distinct stages: pre-impregnation of slot insulation, insertion of winding, and compaction. By separating these operations, the process achieves effective cavity elimination without requiring lengthy continuous impregnation cycles, thereby reducing overall manufacturing time while maintaining dielectric strength.
2Reliability
If higher temperatures and longer process times are used for impregnation, then resin absorption increases and cavities are reduced, but unwanted resin layers form on outer diameter and drips occur at winding head
Solution Approach 1:
The slot insulation is pre-impregnated with resin before winding insertion. This preliminary action creates a resin reservoir at the slot insulation that controls resin flow during subsequent compaction, ensuring adequate resin penetration into cavities without excessive resin migration to the outer diameter or winding head, thereby eliminating the need for high-temperature prolonged heating.
Solution Approach 2:
The process changes the timing parameter of resin application rather than relying on temperature and time extensions. By applying resin beforehand to the slot insulation, the system achieves complete cavity filling at lower temperatures and shorter durations, preventing resin overflow and unwanted layer formation while maintaining effective cavity elimination.
3Manufacturing precision
If the cover slide is inserted last to complete the groove, then groove coverage is improved, but radial displacement creates empty spaces and cavities between winding wires
Solution Approach 1:
The slot insulation is pre-impregnated with resin before the cover slide is inserted. This preliminary resin saturation ensures that when the cover slide is subsequently inserted and compaction occurs, resin is already present to fill any gaps created by radial displacement, maintaining high fill level and eliminating cavities while still achieving complete groove coverage.
Solution Approach 2:
The pre-applied resin acts as an intermediary substance between the cover slide and winding wires. During cover slide insertion and compaction, this resin fills the spaces created by radial displacement, ensuring continuous electrical insulation and maintaining high fill level without requiring the cover slide to be positioned with extreme precision.
4Ease of manufacture
If trickle impregnation is used for defined processes, then resin application control is improved, but resin flow into slots is insufficient for axially longer lamination stacks
Solution Approach 1:
The slot insulation is pre-impregnated with resin before winding insertion. This preliminary action ensures that sufficient resin is already present in the slot insulation to fill all cavities throughout the entire axial length of the lamination stack, eliminating the insufficiency problem of trickle impregnation for long stacks while maintaining the controlled application benefits.
Solution Approach 2:
The pre-impregnated slot insulation serves as an intermediary resin reservoir that distributes resin throughout the slot during compaction. This intermediary approach ensures adequate resin quantity reaches all areas of axially longer lamination stacks, overcoming the limitation of trickle impregnation where resin flow is insufficient for extended axial lengths.
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
Enhances dielectric strength, reduces thermal resistance, and improves heat dissipation by up to 10-15%, while reducing impregnation time and resin consumption, ensuring reliable operation of dynamo-electric machines.
Implementation Method 1
During a gelation phase, in which a viscosity of the impregnating resin increases, pressure is applied radially from the inside to the cover slide towards the bottom of the slot, thus compacting the slot contents. Voids are eliminated.
Implementation Method 2
During a gelation phase, in which a viscosity of the impregnating resin increases, pressure is applied radially from the inside to the cover slide towards the bottom of the slot, thus compacting the slot contents. Voids are eliminated.
Implementation Method 3
This prevents glow discharges and reduces thermal resistance. The impregnation also provides mechanical strengthening.
Implementation Method 4
During a gelation phase, in which a viscosity of the impregnating resin increases
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method for manufacturing a stator (2) of a dynamoelectric machine (1): - Providing a magnetically conductive body of a stator (2) of a dynamoelectric machine (1) with substantially axially extending slots (7), in particular a hollow cylindrical laminated core (9), wherein the slots (7) have a slot (14), slot side walls (21) and a slot base (13), wherein slot teeth (12) are formed between the slots (7), - Inserting a winding system (19) into the slots (7), wherein winding heads (6) are formed on the end faces of the magnetically conductive body, wherein the winding system (19) comprises electrical conductors, in particular winding wires (10), - Inserting a cover slide (15) onto the winding of a slot (7) on the side facing a slot (14), as a radial termination of the windings to the slot (14), - Applying, in particular by trickling, impregnating resin onto the winding heads (6),at least on one end face of the magnetically conductive body, wherein the impregnating resin, due to its comparatively low viscosity, capillarizes essentially axially into the groove area between the electrical conductors, in particular winding wires (10), - exerting radial pressure on the cover slides (15) of the respective groove (7), so that the groove contents - i.e., the individual winding wires (10) of this groove (7) - are compressed and compacted during the gelling phase of the impregnating resin, until the cover slides (15) remain in their pressurized position in the respective groove (7) and/or the impregnating resin is evenly distributed in the respective groove (7).