Stator Slot Varnish Filling Using a Temperature Gradient
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Solution Overview
Problem
The existing methods for manufacturing stators in rotary electric machines face challenges in achieving a high varnish filling rate in the slots, leading to reduced efficiency and increased complexity due to the need for varnish injection in different directions and the inclusion of an inversion step.
Innovation Solution
A method involving a temperature difference across the stator core, where the injection side is maintained at a lower temperature for high viscosity and the opposite side at a higher temperature for gelation, allowing for efficient varnish injection and prevention of flow-out, thereby increasing the filling rate and reducing bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large amount of varnish is injected to increase the filling rate in the slot, then the filling rate can be improved, but the varnish flows out from the lower side of the stator core causing the filling rate to decrease
Solution Approach 1:
The invention changes the temperature parameter of the varnish during injection. The varnish is heated to a temperature where its viscosity decreases, allowing it to flow easily and fill the slots completely. After injection, the varnish is cooled to increase viscosity and prevent flow-out from the lower side, thus resolving the contradiction between achieving high filling rate and preventing varnish loss.
Solution Approach 2:
The invention utilizes the phase transition of the varnish between liquid and gel states through temperature control. By heating the varnish to a liquid state with low viscosity during injection, it can penetrate the slots effectively. Subsequent cooling transitions it to a gel state with high viscosity, preventing flow-out and maintaining the achieved filling rate.
2Manufacturing precision
If varnish is injected in different directions in the first supply step and the second supply step, then the filling rate can be improved, but the work becomes complicated due to the inversion step
Solution Approach 1:
Instead of changing the injection direction through inversion, the invention changes the temperature parameter of the varnish to control its viscosity. This allows continuous injection from a single direction while achieving complete slot filling, eliminating the need for inversion steps and reducing process complexity.
Solution Approach 2:
The invention extracts and eliminates the inversion step from the manufacturing process. By using temperature control to manage varnish viscosity, the process removes the complicated inversion operation while maintaining effective varnish distribution in the slots.
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 approach enhances the varnish filling rate, prevents varnish flow-out, reduces bubble formation, and stabilizes the characteristics of the rotary electric machine by ensuring effective insulation and heat dissipation.
Implementation Method 1
a resin member of which viscosity is low at a first temperature and the viscosity is high at a second temperature higher than the first temperature
Implementation Method 2
the gelling is started near a position at which the gelling is started in the first supply step
Data Source
AI summary
An object of the present invention is to suppress an outflow of varnish from a lower portion of a stator core by increasing a filling rate of varnish in a slot. Provided is a method for manufacturing a stator of a rotary electric machine. The stator has a coil and a stator core in which a slot that houses the coil is formed, and a resin member of which viscosity is low at a first temperature and the viscosity is high at a second temperature higher than the first temperature is filled in the slot from an injection side. The manufacturing method includes a first step of causing a temperature difference in the stator core such that the injection side becomes the first temperature and an opposite side of the injection side becomes the second temperature, and a second step of injecting the resin member from the injection side in a state in which the temperature difference is maintained.