Electromagnetic Relay Deicing via Off-State Joule Heating

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Solution Overview

Problem

Electromagnetic relays in electric vehicles are prone to icing, leading to operational failures and increased energy loss due to repeated on/off cycles or active warming methods, which degrade electricity efficiency.

Innovation Solution

An electromagnetic relay deicing system that uses a control circuit to maintain an off-state and conduct electricity between the common and normally closed terminals, heating the movable piece and adjacent components to melt ice on the normally open terminal, thereby deicing the relay without increasing on/off operations or requiring additional apparatus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electromagnetic relay is repeatedly turned on and off to remove ice, then ice particles and ice films are broken and removed, but energy loss increases and operational reliability decreases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidenergy loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical hammering action (repeated on/off cycling) with an electrical heating method. By applying current to the movable piece during the off-state, ice is melted through thermal effect rather than mechanical impact, thereby removing the harmful factors without the energy waste and reliability issues associated with repeated mechanical operations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent converts the harmful effect of ice accumulation into a beneficial heating process. By intentionally allowing the relay to be in the off-state and applying current to melt the ice, the system uses the electrical current that would otherwise be wasted to serve a useful deicing function, transforming a potential loss into a beneficial action

Inventive Principle:

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

2Reliability

If active warming methods are used to prevent icing, then operational failures are prevented, but electricity efficiency decreases

Engineering Contradiction:

Improveoperational reliabilityVSAvoidelectricity efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous warming, the patent employs periodic action by utilizing the off-state intervals naturally occurring in the relay's operation cycle. Deicing is performed only when the relay is off, converting what would be idle time into a productive deicing period, thereby maintaining reliability without continuous energy consumption

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system uses the relay's own operational characteristics (the necessary off-state periods) to perform self-deicing. No external heating apparatus is needed; the relay's inherent operational cycle provides the opportunity for self-maintenance, improving efficiency while ensuring operational reliability

Inventive Principle:

Principle #25Self-service

3Temperature

If the electromagnetic relay is kept in on-state to prevent icing, then ice formation is reduced, but the relay cannot perform switching functions

Engineering Contradiction:

Improvecontact temperatureVSAvoidswitching function

Core Design Contradiction:

TemperatureVSEase of operation

Solution Approach 1:

The patent applies preliminary action by performing deicing during the off-state before the relay needs to switch to the on-state. This ensures that when the relay transitions to the on-state for normal operation, the contacts are already free of ice, preventing ice formation during critical switching moments without compromising switching functionality

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

This method effectively deices the electromagnetic relay during its off-state, reducing energy loss and preventing operational failures without the need for frequent on/off cycles or additional apparatus, while maintaining efficient electricity supply.

Implementation Method 1

the control circuit deices the electromagnetic relay by causing, during the off-state of the electromagnetic relay, electric conduction between the common terminal and the normally closed terminal connected by the movable piece so that ice on a surface of the normally open terminal melts

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10930457B2Electromagnetic relay deicing system including control circuit

Publication Date: 2021.02.23 SUBARU CORP

AI summary

An electromagnetic relay deicing system includes an electromagnetic relay that includes a common terminal, a normally open terminal, and a normally closed terminal and that supplies electric power from an electric power supplier to an electrical apparatus when the common terminal and the normally open terminal are connected, and a control circuit that controls an on-state and an off-state of the electromagnetic relay. During the on-state of the electromagnetic relay, the common terminal and the normally open terminal are connected by a movable piece. During the off-state of the electromagnetic relay, the common terminal and the normally closed terminal are connected by the movable piece. The control circuit deices the electromagnetic relay by causing, during the off-state of the electromagnetic relay, electric conduction between the common terminal and the normally closed terminal connected by the movable piece so that ice on a surface of the normally open terminal melts.