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Electric Motor Cooling System and Method

IP.com Disclosure Number: IPCOM000202897D
Publication Date: 2011-Jan-07
Document File: 4 page(s) / 164K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system for cooling an electric motor is disclosed. An electric motor comprises a moving rotor and a stationary stator with a relatively small air gap between the rotor and stator. The rotational motion of the rotor drives a shaft, and both rotor and shaft rotate relative to the stator. The shaft comprises a coolant passage in a hollow area of the shaft. Pressurized phase-changing coolant in its liquid state enters the coolant passage at a coolant inlet and exits via a number of cooling jets that are positioned such that coolant is delivered to the stator, end turns of the stator, and other parts of the motor that require cooling. The coolant quickly vaporizes when it encounters warm motor components. Coolant in its gaseous state exits the motor through vapor return ports, travels to a condenser that cools the gaseous coolant and returns it to its liquid state, and the re-liquefied coolant can again be injected into the motor.

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Electric Motor Cooling System and Method

Abstract

    A method and system for cooling an electric motor is disclosed. An electric motor comprises a moving rotor and a stationary stator with a relatively small air gap between the rotor and stator. The rotational motion of the rotor drives a shaft, and both rotor and shaft rotate relative to the stator. The shaft comprises a coolant passage in a hollow area of the shaft. Pressurized phase-changing coolant in its liquid state enters the coolant passage at a coolant inlet and exits via a number of cooling jets that are positioned such that coolant is delivered to the stator, end turns of the stator, and other parts of the motor that require cooling. The coolant quickly vaporizes when it encounters warm motor components. Coolant in its gaseous state exits the motor through vapor return ports, travels to a condenser that cools the gaseous coolant and returns it to its liquid state, and the re-liquefied coolant can again be injected into the motor.

Background

    Heat generated during operation of an electric motor must be dissipated from the motor to prevent degradation of the windings and magnetization losses. Air cooling is commonly used, but has limited effectiveness, particularly in dirty environments. Further, the effectiveness of air cooling is influenced by ambient temperature. Liquid cooling is capable of dissipating more heat than air cooling, and is less influenced by ambient temperature, but poses challenges in adequately cooling the end turns of the stator and the gap between the rotor and the stator. In particular, it is extremely important that the gap between rotor and stator be relatively small for the sake of efficiency; however, the smallness of the gap limits the amount of air or liquid that can enter the gap to cool the motor. These factors tend to limit motor power density. A phase-changing coolant is extremely effective at dissipating heat; however, current motor cooling systems and methods that use phase-changing coolant tend to inadequately cool the end turns of the stator. Thus, a system and method for adequately cooling all critical components of an electric motor using phase-changing coolant is desired.

Description

    Referring to Figure 1, one embodiment of a motor 1 cooled by the disclosed method is depicted. Motor 1 is an electric motor comprising a motor housing 28 capable of containing the components of motor 1 and phase-changing coolant for providing cooling to motor 1. Motor housing 28 may comprise multiple sections, for example housing 28 may comprise a cylindrical sidewall and two end caps. To prevent leakage of coolant, a housing seal 26 is situated between the various sections of motor housing 28. Housing seal 26 may comprise a rubber O- ring, or other suitable material and form factor, capable of being placed between sections of motor housing 28. Vapor return ports 20 comprise openings in motor housing 28 capable of allowing vaporized coolant to exit motor 1...