Electric Working Machine Tool-Specific Motor Speed Control
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Solution Overview
Problem
Existing electric working machines, such as brush cutters, face inefficiencies in power consumption and noise levels due to a single automatic speed shifting function that does not adequately account for the differences between tools like metal blades and nylon cord cutters, leading to unnecessary power usage and noise.
Innovation Solution
An electric working machine with a control circuit that selectively sets a target rotational frequency based on the attached tool, limiting the motor's speed to match the tool's requirements, reducing power consumption and noise by varying the maximum rotational frequency and number of speed stages depending on the tool attached, and adjusting based on load detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single automatic speed shifting function is used for all tools, then the structure is simple, but power consumption is excessive and noise increases
Solution Approach 1:
The patent applies local quality by setting different maximum rotational frequencies for different tool types. The control circuit identifies the attached tool and configures the automatic speed shifting function with tool-specific parameters, allowing each tool to operate at optimal speeds rather than using a universal speed schedule. This resolves the contradiction by making the speed control adaptive to local tool requirements while maintaining the overall automatic speed shifting structure.
Solution Approach 2:
The patent implements dynamics by making the maximum rotational frequency configurable and changeable based on the attached tool. The control circuit dynamically adjusts the speed shifting parameters when a tool is attached or changed, transforming the fixed speed control into an adaptive system that automatically optimizes power consumption for each specific tool configuration.
2Ease of operation
If a single automatic speed shifting function is used for all tools, then the device is easy to operate, but noise levels increase
Solution Approach 1:
The patent reduces noise by applying local quality through tool-specific maximum rotational frequency settings. The control circuit identifies the attached tool type and configures appropriate speed limits, ensuring that noise-sensitive tools like nylon cord cutters operate at lower frequencies while robust tools like metal blades can operate at higher frequencies. This maintains ease of operation as the system automatically adapts without user intervention.
3Productivity
If the motor rotates at high speed for all tools, then productivity is high, but power consumption increases unnecessarily
Solution Approach 1:
The patent applies parameter changes by modifying the maximum rotational frequency parameter based on the attached tool type. The control circuit changes this critical parameter to match tool requirements, allowing high-speed operation for tools that benefit from it (metal blades) while limiting speed for tools that don't (nylon cord cutters). This resolves the contradiction by making productivity optimized for each tool rather than uniformly high across all tools.
Data Source
AI summary
One aspect of the present disclosure provides an electric working machine. The electric working machine includes a driver, a motor, and a control circuit. Attached to the driver is a selected tool. The motor drives the selected tool attached to the driver. The control circuit sets a target rotational frequency based on the selected tool. The control circuit controls the motor to rotate at the target rotational frequency.