Direct Stator Cooling Assembly for Electric Motor Hot Spots
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Solution Overview
Problem
Electric motors generate significant heat during operation, particularly at the ends of the stator wires, which can lead to motor failure if not adequately cooled. Existing cooling systems are ineffective due to poor heat transfer from the stator to the casing.
Innovation Solution
A cooling assembly is integrated into the electric motor, comprising an inlet that delivers a stream of liquid coolant directly onto the outer surface of the stator, particularly the ends of the stator wires, and an accumulator tank that separates dissolved gases from the coolant, allowing air to escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling assembly is added to cool the stator, then the temperature of the stator is reduced, but the device complexity increases
Solution Approach 1:
The cooling assembly is nested within the motor housing structure, with the inlet integrated into the casing and the coolant stream directed through the stator windings. This nesting approach allows the cooling function to be incorporated without adding significant external complexity to the motor assembly.
Solution Approach 2:
A liquid coolant system is implemented using hydraulic principles, where a pump circulates coolant through inlet passages that deliver the coolant directly to the stator windings. The outlet collects and returns the coolant, creating a closed-loop hydraulic cooling system that effectively removes heat from the stator.
2Loss of energy
If coolant is delivered directly onto the stator wires, then heat transfer efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The cooling system is designed to deliver coolant locally to the specific regions of the stator windings that generate the most heat. The inlet is positioned and oriented to target the stator wire ends, providing concentrated cooling where it is most needed rather than uniform cooling across the entire stator assembly.
Solution Approach 2:
The inlet is pre-positioned and pre-oriented during manufacturing to deliver the coolant stream at the optimal angle and location before the motor begins operation. This preliminary positioning ensures that the coolant immediately contacts the hot stator windings upon system startup, maximizing heat transfer efficiency from the beginning of operation.
3Reliability
If an accumulator tank is added to separate dissolved gas, then the reliability of the cooling system is improved, but the device complexity increases
Solution Approach 1:
The accumulator tank is designed to extract and separate dissolved gases from the coolant stream. As coolant circulates through the accumulator, gas bubbles are separated from the liquid phase and vented to the atmosphere or collected for removal, preventing gas accumulation that would otherwise reduce cooling efficiency and system reliability.
Solution Approach 2:
The accumulator tank serves as an intermediary component between the coolant outlet and the pump. It provides a buffer zone where coolant can be temporarily stored and degassed before being pumped back into the system, mediating the flow and protecting the pump from gas ingestion while maintaining continuous cooling operation.
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 cooling system effectively reduces the temperature of the stator and rotor, preventing overheating and motor failure, while allowing smaller electric motors to handle larger loads without overheating.
Implementation Method 1
an inlet configured to deliver a stream of liquid coolant into the motor casing and directly onto an outer surface of a stator to cool the stator
Implementation Method 2
an accumulator tank in fluid communication with the outlet, the accumulator tank configured to separate dissolved gas from the liquid coolant and to allow air to escape the accumulator tank
Data Source
AI summary
This disclosure pertains to a system for cooling an electric motor including a rotor which is connected to an output shaft, a stator disposed about the rotor, a casing in which the stator and rotor are disposed, and a cooling assembly. The cooling assembly includes an inlet configured to deliver coolant into the casing and directly onto the stator to cool the stator and an outlet configured to remove the coolant from the casing. The stator is a major source of heat within the electric motor and applying coolant directly to onto the stator is an effective method of cooling the motor.