Rotating Electric Machine Refrigerant Guide for Accurate Coil Temperature Detection

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Solution Overview

Problem

Conventional rotating electric machines face challenges in accurately detecting coil temperature due to the influence of refrigerant temperature on thermistors, which can lead to inadequate cooling control and potential heat damage.

Innovation Solution

A rotating electric machine design that includes a refrigerant path and guide member to direct refrigerant flow away from the temperature detecting element, allowing it to accurately measure coil temperature without direct contact, and optionally using a heatproof heat insulating member to further isolate the sensor from refrigerant effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a thermistor is provided in contact with a coil end portion to detect coil temperature, then coil temperature can be detected, but the temperature detection accuracy deteriorates when refrigerant flows on the thermistor surface

Engineering Contradiction:

Improvecoil temperature detection accuracyVSAvoidrefrigerant temperature influence on thermistor

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The temperature detecting element is extracted from the direct refrigerant flow path by positioning it on the inner circumferential surface of the stator core away from the coil end portion, while still maintaining thermal contact through the stator core structure to detect coil temperature indirectly without refrigerant interference

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The stator core serves as an intermediary medium that transfers thermal information from the coil to the temperature detecting element. The refrigerant flow guide member acts as another intermediary to direct refrigerant flow away from the sensor while maintaining cooling function

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If refrigerant is directed onto coil end portions for cooling, then cooling effectiveness is improved, but temperature detection accuracy deteriorates due to refrigerant contact with sensor

Engineering Contradiction:

Improvecoil cooling effectivenessVSAvoidcoil temperature detection accuracy

Core Design Contradiction:

TemperatureVSMeasurement precision

Solution Approach 1:

The coil end portion cooling function is segmented from the temperature detection function. The refrigerant flow guide member divides the cooling area into multiple zones, with refrigerant directed to specific areas while the temperature sensor is positioned in a separate zone free from refrigerant contact

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different areas of the coil end portion are treated differently: some areas receive direct refrigerant flow for cooling, while the area where the temperature sensor is positioned is protected from refrigerant contact to maintain detection accuracy, creating localized functional zones

Inventive Principle:

Principle #3Local quality

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

Enables precise coil temperature detection and effective cooling control, preventing heat damage by isolating the temperature sensor from refrigerant temperature influences, thus ensuring reliable operation and extending the lifespan of the machine.

Implementation Method 1

a refrigerant path defined between the stator core and a case member placed on an external circumferential surface of the stator core, for causing the refrigerant fed from outside into the case member to flow toward the respective coil end portions

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

a guide member for splitting the refrigerant having flowed through the refrigerant path into a first refrigerant flow and a second refrigerant flow to cause the first refrigerant flow and the second refrigerant flow to drop toward the coil end portion

Methodology Applied

Scientific EffectFluid flow splitting:

Implementation Method 3

a temperature detecting element placed in contact with the coil end portion, for detecting coil temperature, wherein the temperature detecting element is provided so as to stay away from the refrigerant flowing on the coil end portion

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS8110952B2Rotating electric machine having guide or outlets for splitting refrigerant

Publication Date: 2012.02.07 TOYOTA JIDOSHA KK

AI summary

To provide a rotating electric machine capable of accurate detection of coil temperature by causing refrigerant to flow so as not to contact a temperature detecting element provided on a coil end portion. A rotating electric machine (10) comprises: a cylindrical stator core (12); coils (16) wound around a plurality of teeth (14) projecting from an inner circumferential surface of the stator core (12) and having coil end portions (18) protruding beyond respective end portions in an axial direction of the stator core (12); a cooling part (50) to cool the coil (16) by dropping refrigerant onto the coil end portions (18); and a temperature detecting element (30) placed in contact with the coil end portion (18), for detecting coil temperature. The temperature detecting element (30) is provided so as not to directly contact the refrigerant flowing on the coil end portion.