Electric Work Machine Dual-Switch Motor Stop Control
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Solution Overview
Problem
Electric work machines often fail to properly stop the motor when user operation is not correctly transmitted to the control circuit due to switch failures, leading to unintended motor operation.
Innovation Solution
Incorporating a dual-switch system with a control circuit that processes information from both switches to ensure accurate motor control, and a drive stop circuit for hardware-based interruption of motor operation, preventing unintended motor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single switch is used to control the motor, then the device complexity is reduced, but the reliability deteriorates because the motor may not stop properly when the switch fails
Solution Approach 1:
The single switch is divided into two separate switches (first switch and second switch) that both need to be in the on-state for the motor to operate. This segmentation ensures that if one switch fails, the other can still prevent unintended motor operation, thereby improving reliability while maintaining relatively simple device complexity.
2Reliability
If dual-switch system is implemented, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The control circuit merges the signals from the first switch and second switch through a logical AND operation. The motor control circuit only outputs a drive command when both switches indicate the on-state, combining multiple control inputs into a unified decision-making process that improves reliability without significantly increasing overall system complexity.
3Reliability
If hardware-based drive stop circuit is added, then the reliability is further improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
A drive stop circuit is introduced as an intermediary component between the control circuit and the motor drive circuit. This circuit receives the drive command from the control circuit and has the authority to interrupt it, ensuring the motor can be stopped reliably even if the control circuit malfunctions. The drive stop circuit acts as a safety mediator that improves reliability while adding a manageable level of manufacturing complexity.
Data Source
AI summary
An electric work machine includes a motor, a manipulator, a first switch, a second switch, and a control circuit. The manipulator is on-operated or off-operated by a user of the electric work machine. Each of the first switch and the second switch is turned on or off in response to the manipulator being on-operated or off-operated. The control circuit executes a motor control process in accordance with a computer program. The control circuit receives first switch information from the first switch, and receives second switch information from the second switch. The motor control process outputs a drive command for driving the motor in response to the first switch information and the second switch information indicating that the manipulator is on-operated.