Dual-Switch Motor Stop Circuit for Electric Work Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric work machines often fail to properly stop the motor when user operation is not transmitted correctly due to switch failures, leading to unintended motor operation.
Innovation Solution
The electric work machine incorporates a control circuit that utilizes both first and second switches to execute motor control, with a drive stop circuit operating via hardware processing to ensure the motor is stopped even if the user's operation is not properly transmitted, using a stop signal to interrupt the drive command.
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 control circuit is segmented into multiple independent switches (first switch and second switch) that work together to control the motor. This segmentation allows the system to detect switch failures by comparing the states of multiple switches, thereby improving reliability without requiring a complete redesign of the control architecture.
Solution Approach 2:
A drive stop circuit is introduced as an intermediary component between the switches and the motor drive circuit. This intermediary circuit receives signals from both switches and executes the motor stop command when either switch indicates an off-state, ensuring reliable motor stopping even when one switch fails. The drive stop circuit acts as a mediator that resolves the conflict between switch failure and motor control reliability.
2Speed
If software processing is used for motor control, then the control flexibility is improved, but the response speed deteriorates when hardware-level intervention is needed
Solution Approach 1:
The patent replaces software-based motor control with a hardware-level drive stop circuit that directly interrupts the motor drive signal. This substitution eliminates the delay associated with software processing and provides immediate motor stopping response. The drive stop circuit uses hardware logic to detect switch states and execute stop commands at the electrical level, achieving faster response times compared to software-based control.
3Object-affected harmful factors
If the control circuit relies solely on the first switch, then the device complexity is minimized, but the harmful factors increase due to unintended motor operation when the switch fails
Solution Approach 1:
The control system implements feedback by continuously monitoring the states of both the first and second switches and using this information to control motor operation. The drive stop circuit receives feedback from both switches and adjusts the motor drive signal accordingly, ensuring that the motor stops when either switch indicates an off-state. This feedback mechanism prevents unintended motor operation that would occur with a single switch system.
Solution Approach 2:
The system prepares for potential switch failures by having the drive stop circuit continuously monitor both switches and be ready to execute a stop command at any moment. This beforehand cushioning ensures that if either switch fails, the motor can be immediately stopped, preventing harmful unintended operation. The drive stop circuit is pre-configured to prioritize safety over continuous operation.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric work machine in one aspect of the present disclosure 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.