Excavator Charging Cable State Control for Safe Limited Motion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing work machines face inefficiencies and safety risks during battery charging due to the need to stop operations when connecting or disconnecting charging cables, which can lead to reduced productivity and potential damage or electric shock.
Innovation Solution
A control system that detects the connection state of a charging cable and performs suppression processes to limit the work machine's actions while allowing safe operation, including reducing motor and actuator outputs, ensuring the battery remains non-chargeable during cable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is stopped during battery charging, then safety is improved, but work efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the work machine's operational state flexible rather than fixed. The control unit dynamically adjusts the operational restrictions based on real-time detection of cable connection status. When the charging cable is connected, the system permits limited operations (traveling and rotating) while suppressing other actions, and when disconnected, it allows full operational freedom. This dynamic adaptation resolves the contradiction by enabling safe yet productive operation during charging.
2Productivity
If the work machine is allowed to perform actions during battery charging, then work efficiency is improved, but safety deteriorates due to potential cable damage and electric shock
Solution Approach 1:
The patent applies local quality by implementing differentiated operational restrictions for different machine functions during charging. Instead of uniformly stopping all operations, the system selectively permits certain actions (traveling and rotating) while suppressing others (hydrostatic actuators and electric motor-driven actions). This localized control approach allows the machine to maintain productivity through safe operations while preventing cable damage and electric shock risks associated with high-power actions.
Solution Approach 2:
The patent applies feedback by continuously monitoring the charging cable connection status through detection units and using this information to adjust operational permissions in real-time. The control unit receives feedback signals about cable connection state and dynamically modifies the operational restrictions accordingly. This closed-loop control ensures that operational permissions are always aligned with the actual charging status, maintaining both safety and work efficiency.
3Productivity
If the charging cable remains connected during work machine movement, then work efficiency is improved, but the cable may be damaged causing electric shock
Solution Approach 1:
The patent applies preliminary action by proactively suppressing potentially harmful machine actions before they can occur during charging. The control unit preemptively restricts operations that could damage the charging cable (such as rapid acceleration, high-power hydraulic actions, and sudden movements) while allowing safer operations. This preventive approach eliminates the need to disconnect the cable for safety reasons, enabling continuous operation and maintaining work efficiency while preventing cable damage and electric shock hazards.
Data Source
AI summary
A hydraulic excavator as a work machine includes a battery that stores electric power, a connector to which a charging cable used to charge the battery is connected, and an electric motor that is driven by electric power supplied from the battery. A method of controlling the hydraulic excavator includes detecting a connection state between the charging cable and the connector, and performing a suppression process of suppressing an action of the hydraulic excavator while permitting the action of the hydraulic excavator based on the connection state in a case where the electric motor is in a rotatable state.