Door opening and closing device for refrigerator and method of controlling the same
Find Innovative SolutionsGenerate Solutions
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 inefficiencies, 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 utilizing a low-powered compact motor with a back electromotive force (EMF) measurement system, a control unit, and a gasket separation mechanism to efficiently manage door operation, allowing for automatic opening and closing while reducing the force required for manual operation and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a motor is connected to a hinge unit to enable automatic door opening and closing, then automation is improved, but the device requires a large actuator due to the significant difference between gasket separation force and door rotation force, increasing device complexity and space requirements
Solution Approach 1:
The door opening operation is divided into two distinct phases: gasket separation and door rotation. A gasket separation mechanism is implemented that uses a push rod to apply force at a position away from the hinge, creating a lever arm that amplifies the motor's rotational force into sufficient linear force for gasket separation. This segmentation allows the motor to be sized for the easier door rotation task while the mechanical leverage handles the harder gasket separation task.
Solution Approach 2:
A push rod acts as an intermediary mechanical element between the motor and the door. The push rod converts the motor's rotational motion into linear pushing motion, and by positioning the push rod away from the hinge axis, it creates a mechanical leverage system that multiplies the force output, enabling a small motor to generate sufficient force for gasket separation.
2Force
If a large actuator is used to provide sufficient force for gasket separation and door rotation, then the required force is improved, but the refrigerator requires increased space to accommodate the large actuator, compromising the size and thermal insulation performance
Solution Approach 1:
The push rod serves as a mechanical intermediary that provides force multiplication through leverage. By positioning the push rod at a distance from the hinge axis, the system creates a lever arm that amplifies the motor's force output, allowing a compact motor to generate sufficient gasket separation force without requiring a large actuator that would consume valuable refrigerator space.
Solution Approach 2:
The system uses mechanical leverage to counterbalance the force deficit. The push rod's positioning creates a torque advantage where a small motor force applied at a greater distance from the hinge can generate sufficient force at the gasket interface, effectively using geometric arrangement to compensate for the small motor size.
3Extent of automation
If the drive unit and opening and closing unit are connected when the door is manually opened, then automatic control is improved, 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 motor and the door opening mechanism is made dynamic rather than static. A clutch mechanism is introduced that can disengage the motor from the door mechanism when manual operation is detected. This allows the system to automatically engage when automatic operation is needed while freely allowing manual operation without resistance, protecting both the user and the motor from damage.
Solution Approach 2:
The clutch acts as an intermediary control element between the motor and the door mechanism. It selectively engages or disengages the mechanical connection based on operational mode, allowing the motor to provide assistance during automatic operation while completely disengaging during manual operation to eliminate resistance and prevent damage.
4Extent of automation
If the motor continuously drives the door during automatic opening and closing operations, then automation is improved, but the motor may be overloaded when extraneous objects or users block the door
Solution Approach 1:
The system incorporates feedback mechanisms including current sensors and back-EMF measurement to monitor motor operating conditions. When the door encounters an obstacle or abnormal resistance during automatic operation, the feedback signals trigger the control unit to stop the motor, preventing overload damage while maintaining automatic operation capability under normal conditions.
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 system enables smooth, efficient door operation with reduced power consumption, allows for automatic completion of door opening and closing, and protects the motor and user by halting operation when obstacles are detected, all while minimizing space requirements.
Implementation Method 1
a drive unit for generating rotational force by means of a motor
Implementation Method 2
a back electromotive force measuring device for measuring a back electromotive force value generated in the motor
Implementation Method 3
a gasket separation mechanism for separating a gasket from a door or a main body when the door is opened
Data Source
Figure 1
Figure 2~3
Figure 4
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.