Lock Valve Control for Faster Hydraulic Actuator Stopping
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Solution Overview
Problem
In work vehicles, unintended operation of actuators can persist even after a lock valve is switched to the locked state due to inertial forces, leading to delayed cessation of unexpected operation during gate lock lever switching.
Innovation Solution
A work machine with a controller that switches the lock valve from the lock position to the release position when the gate lock lever is operated from the permission to the prohibition position, and decides based on pressure sensor data whether pilot hydraulic fluid has been output within a specified time, keeping the lock valve locked if output is detected, and switching it back if no output is detected, thereby preventing unintended actuator operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lock valve is kept in the released state to detect unintended operation, then detection accuracy is improved, but the actuator operation cannot be stopped quickly due to inertial force
Solution Approach 1:
The lock valve is switched to the lock position immediately when unintended operation is detected, before the actuator completes its motion. This preliminary locking action interrupts hydraulic fluid supply to the pilot valve, preparing the system to stop the actuator faster by preventing further hydraulic pressure buildup that would sustain inertial motion
Solution Approach 2:
The system continuously monitors pilot pressure via a pressure sensor and provides feedback to the controller. When the pilot pressure exceeds a threshold within a predetermined time after lock valve release, the controller identifies this as unintended operation and immediately re-locks the valve, creating a closed-loop control system that responds dynamically to actual operating conditions
2Speed
If the lock valve is switched to the lock position immediately after unintended operation detection, then actuator stopping speed is improved, but the system may lock unnecessarily if detection timing is delayed
Solution Approach 1:
The system sets a predetermined time window after lock valve release during which pilot pressure is monitored. This preliminary monitoring period allows the system to distinguish between normal pressure fluctuations and genuine unintended operation, ensuring that locking actions are taken only when truly necessary while still responding quickly to actual hazards
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables faster cessation of unexpected actuator operation by promptly identifying and responding to unintended operation, ensuring actuators stop quickly even if unintended operation occurs during gate lock lever switching.
Implementation Method 1
a pressure sensor that detects the pilot pressure
Implementation Method 2
a lock valve that is switched to a lock position for interrupting a supply of the hydraulic fluid to the pilot valve
Implementation Method 3
a hydraulic pump driven by the engine
Data Source
AI summary
To provide a work machine that can stop unexpected operation of actuators faster than it actually occurs even if unintended operation occurs at the time of gate lock lever switching that leads to such unexpected operation. In the work machine, a controller switches a lock valve from a lock position to a release position in a case where a lock operation device is operated from a permission position to a prohibition position; decides, on the basis of a result of detection by a pressure sensor, whether or not a pilot hydraulic fluid has been output from a pilot valve until first time elapses after the lock valve is switched to the release position; keeps the lock valve at the lock position if it is decided that the pilot hydraulic fluid has been output until the first time elapses; and switches the lock valve from the lock position to the release position if it is decided that the pilot hydraulic fluid has not been output until the first time elapses, and second time elapses.