Pilot Hydraulic Shut-Off Control for Solenoid Sensor Failure
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Solution Overview
Problem
Existing work machines cannot accurately determine whether a solenoid valve is stuck-open, leading to unnecessary actuator inoperability or failure to stop the actuator when stuck-open occurs, due to sensor abnormalities.
Innovation Solution
A work machine with a hydraulic pump, directional control valve, pilot pump, solenoid valve, shut-off valve, and sensors, where a controller determines sensor abnormalities and controls the shut-off valve based on lever operation and sensor signals to prevent unnecessary actuator inoperability and stop the actuator when stuck-open occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shut-off valve is closed to make the actuator inoperable when sensor abnormality is detected, then safety is improved, but availability deteriorates because the actuator becomes inoperable even when the solenoid valve is normal
Solution Approach 1:
The control system dynamically changes the shut-off valve state based on real-time sensor data and lever position. When the lever is neutral, the valve closes to stop the actuator for safety. When the lever is operated, the valve opens to allow actuator operation, maintaining productivity while ensuring safety through dynamic adaptation to operational context.
Solution Approach 2:
The system changes the operational parameter of the shut-off valve (open/closed state) based on the lever operation state. This parameter change allows the system to differentiate between intentional operation (lever moved) and idle state (lever neutral), enabling safe operation even when sensor abnormalities prevent accurate solenoid valve status detection.
2Productivity
If the shut-off valve is opened without exception when sensor abnormality occurs, then availability is maintained, but safety deteriorates because the actuator cannot be stopped when the solenoid valve is stuck-open
Solution Approach 1:
The control system dynamically adjusts the shut-off valve state based on lever position sensing. When the lever is in the neutral state, the system closes the shut-off valve to stop the actuator, ensuring safety. When the lever is operated, the valve remains open to maintain productivity. This dynamic response resolves the contradiction by making the safety measure conditional rather than absolute.
3Measurement precision
If the system cannot determine sensor abnormality accurately, then measurement precision deteriorates, but device complexity increases due to additional sensors and control logic
Solution Approach 1:
The lever position sensing signal acts as an intermediary that enables the control system to infer the intended operator intent and make appropriate control decisions. By using this existing signal, the system can determine when to close the shut-off valve without requiring additional complex sensor arrays or sophisticated diagnostic algorithms, thus maintaining measurement precision while limiting complexity growth.
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
Enables the actuator to be stopped by lever operation without unnecessary inoperability, even when stuck-open of the solenoid valve cannot be sensed, ensuring proper operation and safety.
Implementation Method 1
a solenoid valve that generates a pilot pressure to drive the directional control valve with use of a delivery pressure of the pilot pump as a source pressure
Implementation Method 2
a first sensor that senses the amount of operation of an operation lever
Implementation Method 3
a second sensor that senses a state amount relating to operation of the solenoid valve
Implementation Method 4
a controller that controls the solenoid valve and the shut-off valve on the basis of sensing signals of the first sensor and the second sensor. In the work machine, the controller is configured to determine whether or not an abnormality of the second sensor exists on the basis of the sensing signal of the second sensor
Data Source
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AI summary
In a work machine including a solenoid valve that generates a pilot pressure to drive a directional control valve with use of the delivery pressure of a pilot pump as a source pressure, a shut-off valve that shuts off a hydraulic operating fluid from the pilot pump to the solenoid valve, a first sensor that senses the amount of operation of an operation lever, and a second sensor that senses a state amount relating to operation of the solenoid valve, whether or not an abnormality of the second sensor exists is determined on the basis of a sensing signal of the second sensor. When it is determined that the second sensor is abnormal, on the basis of a sensing signal of the first sensor, an opening command is made to the shut-off valve if operation of the operation lever is sensed, and a closing command is made to the shut-off valve if the neutral state of the operation lever is sensed.