Electric Shovel Charging Interlock for Hydraulic Lockout
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Solution Overview
Problem
Conventional electric shovels do not adequately prevent unauthorized connection of charging cables during operation, posing safety risks as operators may continue working unaware of a third party connecting the cable, leading to potential hazards.
Innovation Solution
The electric shovel is designed with a system that renders the hydraulic actuator inoperable and the electric motor non-activatable when a charging cable is connected to the charging port, ensuring safety by preventing unintended operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging cable is connected to the charging port during operation, then the power storage device can be charged, but the electric motor may be accidentally activated causing safety hazards
Solution Approach 1:
The control system performs preliminary detection to determine whether the charging cable is connected to the charging port before allowing electric motor activation. This preliminary check prevents accidental motor activation during charging by blocking the activation signal when cable connection is detected, while still permitting normal operation when no cable is connected.
2Reliability
If the electric motor is prevented from activating during charging, then safety is improved, but the operator cannot intentionally start the motor when needed
Solution Approach 1:
The control system dynamically adjusts its behavior based on the charging cable connection state. When the cable is connected, the system enters a restricted mode that blocks motor activation to ensure safety. When the cable is disconnected, the system transitions to normal mode where motor activation is permitted, thus adapting the control characteristics to the current operational context.
3Reliability
If the hydraulic actuator is rendered inoperable during charging, then unintended operation is prevented, but the shovel cannot perform work during charging
Solution Approach 1:
The control system performs preliminary detection of the charging cable connection state before permitting hydraulic actuator operation. This preliminary check ensures that the actuator remains inoperable when the cable is connected, preventing unintended operation and safety hazards, while allowing full work capability when no cable is connected.
Data Source
AI summary
A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, a hydraulic actuator that drives driven parts including the lower traveling body and the upper turning body, a main pump that supplies hydraulic oil to the hydraulic actuators, a pump motor that drives the main pump, and a power storage device that supplies electric power to the pump motor. When the charging cable is connected to the charging port during the operation of the shovel, the shovel causes the hydraulic actuators to shift to the inoperable state. When the charging cable is connected to the charging port, the shovel does not start the pump motor even if an input for starting the pump motor is received from a user.