Capacitor Housing Venting in Rotary Electric Machines

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Solution Overview

Problem

In conventional rotary electric machines, high-temperature heat generation in capacitors can lead to pressure buildup and explosion due to electrolyte vaporization, especially during reverse power supply connections.

Innovation Solution

A rotary electric machine design featuring a recess-shaped capacitor housing with a communication passage and heat dissipation material, which allows for effective heat dissipation to a heat sink without causing capacitor explosion, even at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the explosion-proof valve is sealed by a sealing member in a ring shape, then the sealing performance is improved, but the pressure relief capability deteriorates when electrolyte vaporizes at high temperatures

Engineering Contradiction:

Improvesealing performanceVSAvoidpressure buildup leading to explosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sealing member is divided into two distinct parts: a first sealing member that seals the explosion-proof valve in normal operation, and a second sealing member that seals the communication passage. This segmentation allows the system to maintain sealing performance while providing a pressure relief path when needed, as the second sealing member can be designed to fail or open under high pressure conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The communication passage acts as an intermediary element between the capacitor interior and exterior. It provides a controlled path for pressure relief when the electrolyte vaporizes at high temperatures, preventing dangerous pressure buildup while maintaining normal sealing performance through the coordinated action of the first and second sealing members.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If heat dissipation material is disposed outside the sealed space, then heat dissipation is improved, but the capacitor still explodes when electrolyte vaporizes due to reverse power supply connection

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidexplosion prevention

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The harmful effect of electrolyte vaporization is extracted and redirected through the communication passage to the exterior of the capacitor. By providing a dedicated escape path for the vaporized electrolyte, the system prevents pressure buildup and explosion while maintaining effective heat dissipation through the heat dissipation material positioned outside the sealed space.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The potentially harmful vaporized electrolyte that would cause explosion is converted into a beneficial pressure relief mechanism. The communication passage allows the vaporized electrolyte to escape in a controlled manner, transforming what would be a dangerous pressure buildup into a safe pressure relief process that protects the capacitor from explosion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the capacitor is tightly sealed to prevent electrolyte leakage, then sealing performance is improved, but pressure relief capability deteriorates when vaporization occurs

Engineering Contradiction:

Improveelectrolyte containmentVSAvoidpressure buildup from vaporization

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The communication passage is pre-configured and sealed by the second sealing member during normal operation to maintain electrolyte containment. When vaporization occurs due to high temperature or reverse power supply connection, the second sealing member is designed to fail or open, allowing the vaporized electrolyte to escape through the pre-established communication passage, thus providing automatic pressure relief without requiring additional active components.

Inventive Principle:

Principle #10Preliminary action

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

Prevents capacitor explosions by ensuring heat dissipation and pressure relief through the communication passage and heat dissipation materials, maintaining the integrity of the rotary electric machine.

Implementation Method 1

a capacitor heat dissipation material, and the inner peripheral side surface of the capacitor housing portion is joined to the outer peripheral side surface of the capacitor via the capacitor heat dissipation material. Therefore, even if heat is generated at a very high temperature in the capacitor, the heat can be dissipated to the heat sink

Methodology Applied

Scientific EffectHeat dissipation: Conduction (thermal)

Data Source

PatentUS12074507B2Rotary electric machine

Publication Date: 2024.08.27 MITSUBISHI ELECTRIC CORP

AI summary

A rotary electric machine in which a capacitor does not explode even if heat is generated in the capacitor, is provided. A heat sink includes a recess-shaped capacitor housing portion having an inner peripheral side surface joined to an outer peripheral side surface of a capacitor via a capacitor heat dissipation material, and the capacitor housing portion includes an explosion-proof valve recess located at a position facing an explosion-proof valve of the capacitor, and a communication passage providing communication between a drive circuit board and the explosion-proof valve.