Power Tool Safety Control Circuit for Pre-Start Switch Fault Detection
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Solution Overview
Problem
Power tools lack a mechanism to detect circuit failures before the motor is turned on, leading to potential dangers due to undetected transistor damage or static electricity, which can cause motor failure and control abnormalities.
Innovation Solution
A safety control circuit module that includes a control processing device to detect the status of switch units before enabling motor operation, using metal-oxide-semiconductor field-effect transistors and diodes to prevent motor runaway in case of switch unit failure, ensuring safe operation by checking for abnormal signals before allowing the motor to start.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no pre-detection mechanism is implemented, then the device complexity is reduced, but the reliability deteriorates due to undetected circuit failures causing motor runaway
Solution Approach 1:
The control processing device performs preliminary detection of switch unit status before enabling motor operation. The detection circuit checks whether each switch unit is in a normal or failed state prior to motor startup, preventing motor runaway caused by damaged transistors while maintaining relatively simple overall circuit architecture.
2Reliability
If detection circuits are added to check switch unit status, then the reliability is improved, but the device complexity increases
Solution Approach 1:
A detection circuit serves as an intermediary between the control processing device and the switch units. This intermediary circuit enables the controller to indirectly monitor the status of multiple switch units through voltage level detection, achieving reliable fault detection without requiring direct complex interaction with each individual transistor.
Solution Approach 2:
The detection circuit performs multiple functions: it monitors the status of multiple switch units simultaneously, provides fault detection capability, and enables safe motor startup control. This multi-functional approach achieves comprehensive reliability improvement without proportionally increasing circuit complexity.
3Productivity
If the motor is allowed to operate without pre-checking switch unit status, then the productivity is maintained, but the object-affected harmful factors increase due to potential motor failure and control abnormalities
Solution Approach 1:
The system applies preliminary anti-action by detecting switch unit failures before they can cause harmful motor runaway. The detection circuit identifies abnormal switch units in advance, preventing the development of dangerous conditions that would affect the motor and overall system safety, while allowing normal operation to proceed without interruption.
Data Source
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AI summary
A power tool (10) and a safety control circuit module (13) and a safety control method thereof are provided. The power tool (10) includes a power supply device (11), a control processing device (12), a safety control circuit module (13), and a power output device (14). The control processing device (12) is electrically connected with the power supply device (11). The safety control circuit module (13) includes a first switch control circuit (131), a second switch control circuit (132), a third switch control circuit (133), a first resistor (134), and a first diode (135). The power output device (14) includes a first power connection terminal (141) and a second power connection terminal (142). Before switch units of the control circuits are controlled, the control processing device (12) detects whether the switch unit has failed, so as to increase safety.