Ice Maker Bail Arm Actuation Using Shape Memory Alloy

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Solution Overview

Problem

Existing automatic ice maker systems face issues with bail arms being obstructed by ice accumulation, leading to false signaling and increased complexity, cost, and reduced service life due to the need for separate motors and cam arrangements to raise the bail arm prior to ice harvesting.

Innovation Solution

A shape memory alloy (SMA) device is used to automatically raise and lower the bail arm, allowing ice cubes to be dispensed without obstructing the bail arm, and a sensing switch is employed to signal ice production based on ice levels, simplifying the actuation mechanism and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate motor and cam arrangement is used to raise the bail arm prior to ice harvesting, then the bail arm can be raised to prevent ice accumulation, but the overall cost, complexity and size of the automatic ice maker increases

Engineering Contradiction:

Improvebail arm operation reliabilityVSAvoidice maker complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional motor and cam mechanical arrangement with a magnetic field-based actuation system. A permanent magnet mounted on the bail arm interacts with an electromagnet or magnetic sensor on the ice maker body, enabling the bail arm to be raised and lowered through magnetic attraction and release, eliminating the need for complex mechanical drive components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameter from mechanical force transmission to magnetic field interaction. By using magnetic attraction and repulsion forces, the system achieves bail arm actuation without mechanical contact, reducing wear and simplifying the overall mechanism while maintaining reliable operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a separate motor and cam arrangement is used to raise the bail arm prior to ice harvesting, then the bail arm can be raised to prevent ice accumulation, but the service life of the ice maker is reduced due to burden on existing drive components

Engineering Contradiction:

Improvebail arm operation reliabilityVSAvoidice maker service life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The magnetic actuation system eliminates mechanical contact between the bail arm and drive components, removing wear and tear from the original drive mechanism. This extends the service life of the ice maker by preventing degradation of mechanical parts.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The permanent magnet on the bail arm creates a self-contained magnetic coupling system that actuates the bail arm without requiring external mechanical drive components. The magnetic field provides the necessary force directly, reducing the burden on the ice maker's existing drive system.

Inventive Principle:

Principle #25Self-service

3Productivity

If the bail arm is left in the lowered position, then ice production can continue, but ice cubes pile onto the bail arm and prevent it from shifting upward to terminate production

Engineering Contradiction:

Improveice production continuityVSAvoidice level detection accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The magnetic actuation system raises the bail arm in advance before ice cubes are ejected into the storage bin. This preliminary action prevents ice from accumulating on the bail arm, ensuring that the bail arm remains free to move and accurately detect ice level conditions.

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

The SMA device efficiently raises the bail arm before ice harvesting, preventing obstruction and accurately signaling ice levels, thereby enhancing the efficiency and reliability of ice production while minimizing manufacturing complexity and costs.

Implementation Method 1

the actuation of the bail arm is carried out by a shape memory alloy device (SMA) operatively connected to the bail arm. Prior to the ice harvest cycle, voltage is applied to the SMA causing the SMA device to contract and move the bail arm to the raised position

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Data Source

PatentUS7712322B2Ice level sensing device for an automatic ice maker in a refrigerator

Publication Date: 2010.05.11 MAYTAG

AI summary

A device for sensing a level of ice stored in a bin of an automatic ice maker includes a bail arm and an actuator mechanism. The actuator mechanism is constituted by a shape memory alloy that, upon application of a voltage, contracts to move the bail arm to a raised position prior to initiation of an ice harvest cycle. After completion of the ice harvest cycle, the voltage is discontinued, allowing the shape memory alloy to relax, causing the bail arm to return to a lowered position. The bail arm includes a sensing member that extends into the bin and, depending upon the level of ice, prevents the bail arm from contacting a sensing switch, temporarily halting ice production.