Adaptive Braking Control for Electric Tools Based on Inertia
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Solution Overview
Problem
Existing electric tools, such as grinders, face operability issues due to inconsistent braking forces when attaching rotating tools with varying moments of inertia, leading to either excessive user reaction or inadequate stopping performance.
Innovation Solution
An electric tool with a control unit that adjusts the braking force based on the moment of inertia of the attached rotating tool, using methods such as changing the duty ratio of switching elements or employing both electrical and mechanical braking means, to optimize braking performance according to the tool's inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large braking force is applied to stop rotating tools with large moment of inertia, then the stopping performance is improved, but the reaction force applied to the user increases and operability deteriorates
Solution Approach 1:
The braking force is dynamically adjusted based on the moment of inertia of the attached rotating tool. The control unit determines the moment of inertia and sets the braking force accordingly, making the braking system adaptive rather than static. This resolves the contradiction by allowing strong braking when needed (large moment of inertia) while reducing braking force when not needed (small moment of inertia), thus maintaining both stopping performance and operability.
Solution Approach 2:
The braking force parameter is changed according to the moment of inertia of the rotating tool. By detecting the moment of inertia and adjusting the braking force parameter accordingly, the system optimizes the balance between stopping performance and user comfort. This parameter adaptation allows the same braking system to handle different tool configurations effectively.
2Ease of operation
If a small braking force is applied to reduce user reaction, then the operability is improved, but the stopping performance deteriorates when rotating tools with small moment of inertia are attached
Solution Approach 1:
The braking force is dynamically adjusted based on the moment of inertia of the attached rotating tool. The control unit determines the moment of inertia and sets the braking force accordingly, making the braking system adaptive rather than static. This resolves the contradiction by allowing strong braking when needed (large moment of inertia) while reducing braking force when not needed (small moment of inertia), thus maintaining both stopping performance and operability.
Solution Approach 2:
The braking force parameter is changed according to the moment of inertia of the rotating tool. By detecting the moment of inertia and adjusting the braking force parameter accordingly, the system optimizes the balance between stopping performance and user comfort. This parameter adaptation allows the same braking system to handle different tool configurations effectively.
3Device complexity
If constant braking force is applied regardless of rotating tool characteristics, then the control system is simple, but the operability deteriorates due to mismatch between braking force and moment of inertia
Solution Approach 1:
The control unit receives feedback about the moment of inertia of the attached rotating tool and adjusts the braking force accordingly. By monitoring the rotational characteristics and adapting the braking force based on this feedback, the system achieves optimal performance without requiring complex manual configuration. The feedback mechanism enables automatic adaptation to different tool configurations.
Solution Approach 2:
The braking system automatically determines the moment of inertia of the attached rotating tool and sets the appropriate braking force without user intervention. The system serves itself by detecting the tool characteristics and self-adjusting the braking parameters, eliminating the need for manual setup while maintaining optimal operability.
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 solution provides improved operability by tailoring the braking force to the working state, reducing user reaction and ensuring quick stopping of rotating tools with varying moments of inertia, thus enhancing the tool's usability and reducing the need for additional components to prevent lock nut looseness.
Implementation Method 1
the control unit may change the braking force at the time of braking by changing the number of switching elements turned on for the purpose of performing electrical braking
Implementation Method 2
The first braking means may come into contact with and apply a load to a rotation transmission path of the motor and the rotating tool to generate a mechanical braking force
Data Source
Figure 1~3(B)
Figure 4
Figure 5
AI summary
Provided is an easy-to-use electric tool with which braking force can be changed according to work conditions. When an operation switch 5 is turned off, a control unit 50 detects a rotation rate R1 of an electric motor 6. The control unit 50 stands by for a prescribed period, detects a rotation rate R2 of the electric motor 6, and calculates the difference between the rotation rates R1, R2 (R=R1-R2). Since the rotation rate difference R corresponds to the rate of change in rotation rate with time during deceleration of the electric motor 6 and is smaller the larger the moment of inertia of the attached rotary tool, the control unit 50 can determine the moment of inertia of the rotary tool on the basis of the rotation rate difference R. The control unit 50 sets the braking force according to the moment of inertia and performs braking.