Lock Valve Control for Working Vehicle Hydraulic Actuator
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Solution Overview
Problem
Existing methods for determining whether the operating member is in the actuator drive position when the lock member is switched to the release position in working vehicles lack accuracy, leading to potential unexpected movements of the hydraulic actuator.
Innovation Solution
The implementation of a system comprising a hydraulic actuator, operating member, pilot valve, actuator control valve, lock member, operation console, lock valve, elapsed time detection unit, pilot pressure determination units, and an error operation monitoring unit, which switches the lock valve based on predetermined time thresholds and pressure conditions to accurately determine the operating member's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a pressure switch is used to determine whether the operating member is in the actuator drive position, then the determination can be made automatically, but the accuracy of the determination is insufficient
Solution Approach 1:
The determination process is divided into multiple independent detection stages: first detecting whether the operating member is in the actuator drive position, then detecting whether the lock member is in the release position, and finally synthesizing these detections to determine error operation. This segmentation allows each detection to be performed with appropriate precision while maintaining overall automation.
Solution Approach 2:
The control unit acts as an intermediary that receives signals from multiple pressure switches (first and second pressure switches) and combines this information with timing data to make the final determination. This intermediary processing layer enables accurate determination by evaluating multiple conditions rather than relying on a single pressure switch signal.
2Ease of operation
If the lock member is switched to the release position while the operating member is in the actuator drive position, then the hydraulic actuator can operate, but unexpected movement may occur
Solution Approach 1:
The system performs preliminary detection of the operating member's position and the lock member's position before allowing actuator operation. By detecting these conditions in advance and determining whether error operation has occurred, the system prevents unexpected movement while ensuring safe operation when conditions are appropriate.
Solution Approach 2:
The system continuously monitors the positions of the operating member and lock member, and the state of the hydraulic actuator, providing feedback to the control unit. This feedback mechanism allows the system to detect error operation conditions and prevent unexpected movement by adjusting the lock valve state based on the detected conditions.
3Measurement precision
If multiple detection conditions and time-based judgments are implemented, then determination accuracy is improved, but the system complexity increases
Solution Approach 1:
The control unit performs multiple functions: it controls the lock valve, detects pressure switch signals, measures elapsed time, determines error operation conditions, and controls the hydraulic actuator. By consolidating these functions into a single control unit, the system achieves high determination accuracy without proportionally increasing overall system complexity.
Solution Approach 2:
The system uses time-based parameters (elapsed time since lock member release) and pressure parameters (pressure switch signals) to create a multi-dimensional determination framework. By changing from simple position detection to time-and-pressure-based detection, the system achieves higher accuracy while the control unit manages the complexity through parameter-based decision logic.
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 precise determination of the operating member's position, preventing erroneous operations and ensuring the hydraulic actuator's safe and controlled operation by distinguishing between intended and unintended movements.
Implementation Method 1
The pilot valve outputs pilot pressure in conformance with operation of the operating member (27). The actuator control valve (24) controls the hydraulic actuator (23) in conformance with input pilot pressure.
Implementation Method 2
The lock valve (26) can switch between a release condition and a lock condition. The lock valve (26) in the release condition allows supply of pilot pressure to the actuator control valve (24). The lock valve (26) in the lock condition shuts off supply of pilot pressure to the actuator control valve (24).
Implementation Method 3
The elapsed time detection unit (46) detects the time that has elapsed from the point in time when the lock member (31) switched from the lock position to the release position.
Implementation Method 4
The pilot pressure determination unit (48) determines whether or not the pilot pressure is greater than or equal to a predetermined pressure.
Data Source
AI summary
A lock valve is switched from lock condition to release condition when a lock member is switched from lock position to release position. When pilot pressure is at least a predetermined pressure when the elapsed time from the point at which the lock member is switched from lock position to release position is at least a first predetermined time, the lock valve is maintained in the release condition. When pilot pressure is at least the predetermined pressure, the continuous time duration is greater than the second predetermined time when the elapsed time is less than the first predetermined time, the lock valve is switched to the lock condition. When pilot pressure is at least the predetermined pressure, the continuous time duration is no more than the second predetermined time when the elapsed time is less than the first predetermined time, the lock valve is allowed to be switched.