Refrigerator Door Control Using Back-EMF and Gasket Separation
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Solution Overview
Problem
Conventional refrigerator door opening and closing systems require large actuators to manage the difference between gasket separation and door rotation forces, leading to inefficiency, increased space requirements, and user safety concerns, especially when manual operation is needed or obstacles are present.
Innovation Solution
A door opening and closing device using a low-powered compact motor with a back electromotive force (EMF) measurement system, a control unit, and a gasket separation mechanism, allowing for automatic operation and reduced force requirements by disconnecting the drive unit during manual opening and reconnecting for automatic closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a motor is connected to a hinge unit to automatically open the door, then the door can be opened automatically, but an excessively large actuator is necessary due to the significant difference between the force required to separate the gasket and the force required to rotate the door
Solution Approach 1:
The door opening operation is divided into two distinct phases: gasket separation and door rotation. A gasket separation mechanism is implemented to first detach the magnetic gasket from the door, reducing the force required for subsequent door rotation. This segmentation allows the motor to be sized appropriately for the lighter rotation task rather than the heavier initial separation task.
Solution Approach 2:
The gasket separation mechanism performs the preliminary action of detaching the gasket from the door before the motor-driven door rotation begins. By separating the gasket in advance, the system reduces the load on the motor during the main door opening operation, enabling the use of a smaller, more efficient actuator.
2Extent of automation
If a large actuator is used to accommodate the force difference, then the door can be opened automatically, but increased space is required which compromises the size or thermal insulation performance of the refrigerator
Solution Approach 1:
By dividing the door opening function into gasket separation and door rotation components, the system eliminates the need for an oversized actuator. The gasket separation mechanism uses minimal space and force, while the door rotation mechanism uses a compact motor sized for the reduced load, thereby preserving refrigerator interior space and thermal insulation performance.
3Extent of automation
If the drive unit and opening and closing unit are connected even when the door is manually opened, then automatic operation is maintained, but a lot of power is required for the user to manually open the door and the drive unit may be broken
Solution Approach 1:
The connection between the drive unit and opening/closing unit is made dynamic rather than static. A disconnect mechanism is implemented that automatically disengages the motor-driven components when manual operation is detected, allowing free manual door movement. When automatic operation is required, the connection is re-established. This dynamic switching enables both automatic operation and easy manual operation without compromising either function.
4Extent of automation
If the motor continues to operate during manual door opening, then automatic control is maintained, but the motor may be overloaded and the user may be injured
Solution Approach 1:
The system dynamically switches between automatic and manual modes based on operation type. During manual door opening, the disconnect mechanism engages, isolating the motor from the door mechanism to prevent overloading and user injury. The control system detects manual operation and appropriately deactivates the motor, ensuring safety while maintaining automatic control capability when needed.
Solution Approach 2:
The control system monitors door operation conditions and provides feedback to determine whether to engage or disconnect the motor. When manual operation is detected, the feedback signal triggers motor disconnection. When automatic operation is required, the feedback signal enables motor engagement. This feedback mechanism ensures safe operation by preventing motor interference during manual door handling.
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 efficient, low-powered operation with reduced space requirements, automatic recognition of manual door opening, and enhanced user safety by halting operation when obstacles are detected, allowing for smooth and natural door movement with reduced user effort.
Implementation Method 1
a back electromotive force measuring device for measuring a back electromotive force value generated in the motor
Implementation Method 2
The gasket is typically magnetic in order to improve sealing performance
Data Source
AI summary
A door opening and closing device for a refrigerator includes a door coupled to a main body, an opening and closing unit including a drive unit for generating rotational force by means of a motor and a door rotating mechanism for opening or closing the door, a device for measuring a back electromotive force generated from the motor, a power circuit connected for supplying power to the motor, a circuit for transmitting back electromotive force of the motor to the device, a control switch for selectively connecting the motor to the circuit or the power circuit, and a control unit for connecting the control switch to the power circuit when the motor is activated, and connecting the control switch to the circuit and opening or closing the door when the motor is deactivated, wherein the control unit closes the door when a predetermined back electromotive force is input to the device.