Explosion Proof Housing Temperature Control System

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Solution Overview

Problem

Housings for electrical equipment in explosive atmospheres face challenges in maintaining temperature ranges, as the strength of enclosure materials decreases at lower temperatures, and excessive heating can lead to ignition hazards, necessitating effective cooling and heating measures to comply with explosion protection regulations.

Innovation Solution

Incorporating a temperature control system with thermal sensors and control devices to activate heating or cooling devices as needed, ensuring the housing temperature remains within permissible limits, using devices like Peltier elements, resistance heating wires, or induction heaters, and circulating heat transfer media to manage temperature extremes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the housing operates in lower ambient temperatures, then the housing can be used in colder environments, but the strength of the enclosure material decreases and the gas pressure increases in case of explosion

Engineering Contradiction:
Improveambient temperature rangeVSAvoidhousing material strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The patent applies parameter changes by actively controlling the housing temperature through heating and cooling devices. The temperature control system adjusts the housing temperature parameter to maintain it within a safe range (above -60°C and below maximum permissible temperature) regardless of ambient conditions, thereby resolving the contradiction between extended temperature range usage and material strength maintenance

Inventive Principle:
Principle #35Parameter changes

2Temperature

If electrical equipment is cooled by convection or heat conduction to housing walls, then the equipment can dissipate heat, but the housing temperature may become too high causing ignition risk or equipment overheating

Engineering Contradiction:
Improveelectrical equipment temperatureVSAvoidignition hazard
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary thermal management system between the electrical equipment and the external environment. This system includes active cooling devices that intermediary control the heat transfer process, preventing direct overheating of equipment while also controlling housing wall temperature to avoid ignition hazards. The intermediary system decouples the temperature control of equipment from the housing temperature

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If active cooling or heating devices are added to extend temperature range, then the ambient temperature range is extended, but the device complexity increases

Engineering Contradiction:
Improveambient temperature rangeVSAvoidtemperature control system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent implements feedback control through temperature sensors that continuously monitor the housing temperature and feed this information to a control device. The control device automatically activates heating or cooling devices based on the sensed temperature, creating a closed-loop feedback system. This automated feedback mechanism extends the operational temperature range while minimizing the need for complex manual control systems

Inventive Principle:
Principle #23Feedback

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 solution extends the ambient temperature range of housings, preventing overheating of electrical equipment and maintaining compliance with explosion protection regulations by actively managing housing temperatures, thereby reducing the risk of ignition and ensuring the housing can operate safely across a broader temperature range.

Implementation Method 1

The thermal sensor can be in the form of an NTC resistor or a radiation pyrometer. According to the invention, the thermocouple or thermosensor is connected directly to the wall so that there is no air gap in between.

Methodology Applied
Scientific EffectThermal sensing: Thermocouple

Implementation Method 2

The cooling device can also include a Peltier element, which is attached to the outside of a housing wall, specifically at a point at which good heat dissipation through the surrounding air is enabled.

Methodology Applied
Scientific EffectHeat dissipation: Convection

Implementation Method 3

The cooling device can also include a Peltier element, which is attached to the outside of a housing wall, specifically at a point at which good heat dissipation through the surrounding air is enabled.

Methodology Applied
Scientific EffectPeltier effect: Peltier Effect

Implementation Method 4

A heating device can be designed, for example, in the form of an electric heating device, with a resistance heating wire

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 5

or in the form of an induction heater, in that a ferromagnetic plate is attached to the relevant walls and is heated by eddy current losses.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 6

The heating and/or cooling device can operate with a heat transfer medium that circulates through the heating and/or cooling device.

Methodology Applied
Scientific EffectHeat transfer: Convection

Data Source

PatentEP2553783B1Explosion proof housing having an expanded ambient temperature range
Publication Date: 2019.03.13 R STAHL SCHALTGERATE GMBH
  • EP2553783B1 patent drawingFigure 1

AI summary

The invention relates to a housing designed for ignition protection according to explosion protection requirement and having a temperature control device. The temperature control device is made of a pipe coil thermally well-connected to at least one of the walls. Optionally, temperature control fluid is carried through the pipe coil by means of a circulating pump in order to increase or decrease the temperature of the housing, depending on the application.