Working Machine Automatic Speed Reduction Control
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Solution Overview
Problem
Existing working machines experience accidental automatic speed reduction when the operation amount of the traveling operation member is steeply changed, leading to unintended shifts in motor speed.
Innovation Solution
Incorporating a controller with an automatic speed reduction unit that calculates a virtual change rate of the operation amount and a corresponding virtual motor rotation speed threshold, preventing accidental speed reductions by delaying judgment and adjusting thresholds based on operation amount changes and prime mover rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If automatic speed reduction is executed based on motor rotation speed threshold when operation amount changes, then speed control responsiveness is improved, but accidental speed reduction occurs during steep operation amount changes
Solution Approach 1:
The system performs preliminary detection of operation amount changes before executing automatic speed reduction. The operation amount change detector identifies steep changes in operation amount, and the controller temporarily suspends automatic speed reduction during these periods, preventing accidental speed reductions while maintaining responsive speed control during normal operations
Solution Approach 2:
The patent introduces an intermediary detection mechanism (operation amount change detector) that mediates between the motor rotation speed threshold detection and the actual speed reduction execution. This intermediary layer filters out false triggers caused by steep operation changes, ensuring that automatic speed reduction only occurs when genuinely needed
2Measurement precision
If motor rotation speed threshold is set corresponding to operation amount, then speed control precision is improved, but accidental speed reduction occurs when operation amount changes steeply
Solution Approach 1:
The system applies preliminary anti-action by detecting steep changes in operation amount and preemptively preventing automatic speed reduction during these periods. The controller monitors operation amount changes and temporarily disables the automatic speed reduction function when steep changes are detected, counteracting the potential harmful effect before it can occur
Solution Approach 2:
The patent dynamically adjusts the automatic speed reduction behavior based on operation conditions. The system transitions between enabling and disabling automatic speed reduction depending on whether steep operation changes are detected, making the control system adaptive to varying operational states and preventing accidental speed reductions while maintaining precision during normal operations
Data Source
AI summary
A working machine includes a traveling motor that is shifted between a first speed and a second speed faster than the first speed, a traveling pump that supplies hydraulic fluid to the traveling motor, a traveling operation member operable to operate the traveling pump, and a controller including an automatic speed reduction unit that performs automatic speed reduction in which the traveling motor having been shifted to the second speed is automatically shifted from the second speed to the first speed based on the operation amount of the traveling operation member. The controller includes an automatic speed reduction restraining unit configured or programmed to restrain the automatic speed reduction from being performed when the traveling operation member is operated to steeply change the operation amount from a first operation amount to a second operation amount.