Door Motor Electromagnetic Braking for Position Holding
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Solution Overview
Problem
Existing door opening and closing systems lack the ability to effectively hold a door at a predetermined position using a motor-generated drive power.
Innovation Solution
A door opening and closing device equipped with a motor, a door position sensor, and a controller that uses a three-phase brushless motor to generate a holding force by braking the rotor's rotation when the door is within a predetermined range, allowing the door to be held at a specific position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a motor is used to generate drive power for door opening and closing, then the door can be automatically opened and closed, but the door cannot be held at a predetermined opening and closing position
Solution Approach 1:
The motor operates in different modes depending on the required function: in drive mode it generates rotational force for door opening/closing, and in holding mode it generates electromagnetic braking force to maintain position. This dynamic switching of operational states allows the same motor to fulfill both automation and position holding requirements.
Solution Approach 2:
The motor serves multiple functions: it acts as both a drive motor for opening/closing the door and as a holding mechanism through electromagnetic braking. By controlling the energization state of the motor phases, it can switch between these functions without requiring separate dedicated components for each purpose.
2Reliability
If additional components like check links are added to hold the door at predetermined positions, then the door position holding capability is improved, but the device complexity increases
Solution Approach 1:
The position holding function is merged with the drive motor by utilizing the motor's electromagnetic braking capability. Instead of having a separate check link mechanism, the motor itself provides the holding force through controlled energization of at least two phases, creating electromagnetic resistance that prevents rotor movement and maintains door position.
Solution Approach 2:
The mechanical check link system is replaced with an electromagnetic braking system. By energizing at least two phases of the motor, electromagnetic forces are generated that create braking torque on the rotor, substituting the mechanical holding action of check links with an electromagnetic equivalent that is more compact and controllable.
3Power
If the motor energizes all three phases for driving, then the drive power is maximized, but the motor cannot generate sufficient holding force when rotating
Solution Approach 1:
The control system changes the energization parameters of the motor based on the operational requirement. For driving, all three phases are energized to maximize power output. For holding, the system switches to energizing only at least two phases, which creates electromagnetic braking force while consuming less energy. This parameter switching allows optimization for each specific function.
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 the door to be securely held at a desired position, improving user convenience and reducing the need for additional check links, while maintaining operational smoothness and preventing unintended door movement.
Implementation Method 1
a motor configured to generate drive power for a door in an opening and closing direction of the door... the motor includes a stator having at least three-phase coils and a rotor provided to be rotatable with respect to the stator, and generates the drive power when the rotor rotates with respect to the stator
Implementation Method 2
in the door holding control, the controller energizes at least two phases of the motor such that rotation of the rotor is braked to generate the holding force
Data Source
AI summary
A door opening and closing device includes a motor which generates drive power for a door in an opening and closing direction of the door, a door position sensor which detects an opening and closing position of the door, and a controller which controls the motor based on the opening and closing position. The motor includes a stator having at least three-phase coils and a rotor. The motor generates the drive power when the rotor rotates with respect to the stator. The controller performs door holding control of generating, as the drive power, a holding force for holding the door at the opening and closing position, in a case where the opening and closing position is within a predetermined range. In the door holding control, the controller energizes at least two phases of the motor such that rotation of the rotor is braked to generate the holding force.