Hand-Held Appliance Mode Selection for Precise Motor Speed Control
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Solution Overview
Problem
Conventional hand-held electric appliances, such as hand blenders, face challenges in precise speed control due to a small actuation path for the speed switch, leading to difficulties in selecting and maintaining a preferred speed for specific applications, and speed changes with load variations, resulting in unfavorable processing results.
Innovation Solution
A hand-held electric appliance with a control unit that selects motor control modes based on user input, allowing for precise control of motor speed, torque, or voltage through predefined modes, including pulse modes, to adapt to different processing needs and load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a small actuation path speed switch is used to control motor speed, then the device structure remains compact and simple, but the user cannot precisely select and hold a particular speed for specific applications
Solution Approach 1:
The control system is segmented into multiple discrete motor control modes (e.g., first through fifth modes) with different actuation characteristics. Each mode divides the speed control range into distinct segments, allowing the user to select precise speed ranges appropriate for specific applications without requiring a continuously complex control mechanism.
Solution Approach 2:
The control system dynamically adapts the actuation path characteristics based on the selected mode. Different modes provide different actuation paths (e.g., first actuation path for low speeds, second actuation path for high speeds), enabling precise speed selection across the entire range while maintaining a simple physical switch structure.
2Reliability
If a simple speed switch with small actuation path is used, then the manufacturing complexity is reduced, but the speed changes with load variations leading to unfavorable processing results
Solution Approach 1:
The control unit receives feedback regarding the actual motor operation and the position of the speed switch. Based on this feedback, the control unit determines the appropriate motor control signal considering the selected motor control mode and the current load conditions, thereby compensating for load variations and maintaining stable speed.
Solution Approach 2:
The system changes control parameters (such as PWM duty cycle, voltage, or current) based on the selected motor control mode and detected load conditions. This allows the motor to maintain consistent performance across varying loads without requiring complex mechanical speed regulation mechanisms.
3Manufacturing precision
If multiple motor control modes are provided for precise speed control, then the processing precision is improved, but the control system complexity increases
Solution Approach 1:
A single control unit implements multiple motor control modes, making the control system universal and multi-functional. The same hardware infrastructure supports various control strategies (e.g., torque control, speed control, power control) through software or firmware configuration, avoiding the need for separate control circuits for each mode.
Solution Approach 2:
The control unit acts as an intermediary between the simple speed switch and the motor. It translates the user's simple switch position into appropriate motor control signals based on the selected mode, providing precise control without exposing the user to system complexity.
Data Source
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AI summary
The invention relates to a hand-held electrically driven domestic appliance (100) and to a corresponding method. The domestic appliance comprises an electric motor (104) for driving the domestic appliance; a control unit (103) for controlling the motor; a first actuation element (101) for outputting a first control signal to the control unit in order to select a motor control mode; and a second actuation element (102) for outputting a second control signal to the control unit. The control unit (103) is designed to select a motor actuation mode from the specified motor actuation modes on the basis of the first control signal, and the control unit (103) is designed to determine a motor actuation signal to be output to the motor (104) on the basis of the selected motor actuation mode and the second control signal.