Hand-Held Blender Motor Control Mode Selection for Load Adaptation
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Solution Overview
Problem
Conventional hand-held electrically driven domestic appliances, such as hand blenders, face challenges in precise speed control due to a small operation path for speed adjustment and undesirable processing results from load changes during food processing, particularly with sticky or uneven foods.
Innovation Solution
A hand-held electrically driven domestic appliance featuring a control unit that selects motor actuation modes based on control signals from operation elements, allowing for precise control of motor speed, torque, or voltage through defined actuation profiles and pulse modes, enabling better handling of varying loads and food consistencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a speed switch with small operation path is used to control motor speed from zero to maximum, then the device structure is compact, but the user cannot easily select and hold a specific control speed
Solution Approach 1:
The continuous speed control range is segmented into multiple discrete speed levels (e.g., 3-5 distinct speeds). The operation element is divided into multiple detectable positions corresponding to these speed levels, allowing the user to select from predefined speed steps rather than attempting to control continuous speed with a small operation path.
Solution Approach 2:
The motor actuation mode dynamically adapts based on the detected position of the operation element. As the user moves the operation element through its small path, the system dynamically transitions between different speed levels, providing precise speed selection despite the limited physical movement range.
2Device complexity
If constant motor actuation is used during processing, then the control system is simple, but the speed changes with load variations causing undesirable processing results
Solution Approach 1:
The control system incorporates feedback from a motor current sensor that continuously monitors load variations. When the operation element is held at a specific position, the system detects changes in motor current and automatically adjusts the motor actuation signal to maintain constant speed, compensating for load changes without requiring complex user intervention.
Solution Approach 2:
The motor actuation parameters (voltage, current, or PWM duty cycle) are dynamically changed based on detected load conditions. The control unit modifies these parameters in real-time to maintain constant motor speed despite variations in processing load, such as when encountering different food consistencies or resistances.
3Force
If high start-up torque is provided for processing tough foods, then the motor can handle high load, but the speed control precision is reduced
Solution Approach 1:
The motor actuation uses periodic pulse signals (PWM) with variable duty cycles. During start-up of high-torque applications, the system applies high-duty-cycle pulses to generate maximum torque, then transitions to lower duty cycles for precise speed control once the load is engaged, achieving both high start-up force and subsequent precision.
Solution Approach 2:
The motor actuation mode dynamically switches between torque-oriented and speed-oriented control based on operating conditions. During start-up or high-load conditions, the system prioritizes torque delivery; once the load is engaged and stable, it transitions to precision speed control mode, adapting the control strategy to the current operational phase.
Data Source
AI summary
The invention relates to a hand-held electrically driven domestic appliance and to a corresponding method for controlling the hand-held electrically driven domestic appliance. The domestic appliance includes an electric motor for driving the domestic appliance; a control unit for controlling the motor; a first actuation element for outputting a first control signal to the control unit in order to select a motor control mode; and a second actuation element for outputting a second control signal to the control unit. The control unit 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 is designed to determine a motor actuation signal to be output to the motor on the basis of the selected motor actuation mode and the second control signal.