Telescopic Boom Hydraulic Control for Full Cylinder Retraction
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Solution Overview
Problem
Existing work machines with multiple extension/contraction hydraulic cylinders face issues where a hydraulic cylinder may not fully contract, leading to potential damage due to misalignment and hydraulic oil leakage, especially when the boom is almost fully contracted.
Innovation Solution
A work machine with a hydraulic circuit and control system that includes a pressure relief solenoid valve and control unit to ensure each hydraulic cylinder is fully contracted by connecting one cylinder to the tank during the contraction of the other, using solenoid valves to manage pressure and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a boom length detector is used to detect the fully contracted state of a hydraulic cylinder, then the boom length detection range is improved, but the measurement precision deteriorates due to variation and hysteresis of the detector
Solution Approach 1:
The invention uses a feedback mechanism where the control unit continuously monitors the operation state of the solenoid valve and the contraction state of the hydraulic cylinder. When the cylinder is detected to be in the fully contracted state, the control unit automatically de-energizes the solenoid valve to prevent further contraction, thereby ensuring precise detection of the fully contracted state despite detector variation and hysteresis.
2Speed
If hydraulic oil pressure is maintained in all cylinders during operation, then the operational speed is improved, but the reliability deteriorates due to hydraulic oil leakage through spool gaps causing unintended cylinder extension
Solution Approach 1:
The invention extracts hydraulic oil from the contraction circuit of the non-operated cylinder through the solenoid valve, directing it to the tank. This ensures that the non-operated cylinder maintains a contracted state by removing hydraulic pressure, preventing unintended extension due to leakage while allowing the operated cylinder to extend at high speed.
3Adaptability or versatility
If the extension/contraction order of hydraulic cylinders is changed to adapt to different operations, then the adaptability is improved, but the device complexity increases due to multiple solenoid valves and control circuits
Solution Approach 1:
The invention implements a dynamic control system where the control unit automatically switches between different extension/contraction orders based on the current boom state and operational requirements. The system can flexibly change the operation sequence of multiple hydraulic cylinders through dynamic switching of solenoid valves, providing adaptability without requiring multiple fixed control circuits.
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
Ensures complete contraction of all hydraulic cylinders, preventing damage and maintaining operational integrity by managing pressure and hydraulic oil flow effectively.
Implementation Method 1
a solenoid valve that switches the extension/contraction hydraulic cylinder to be operated
Implementation Method 2
an extension/contraction cylinder pressure relief solenoid valve that releases pressure to a tank
Data Source
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AI summary
This work machine comprises: a first hydraulic cylinder and a second hydraulic cylinder that telescope a telescopic boom on the basis of hydraulic oil supply and discharge, a switching valve that is disposed on a pressure relief circuit for connecting the first hydraulic cylinder and the second hydraulic cylinder to a tank, and a control unit that causes the switching valve to connect the first hydraulic cylinder to the tank and releases the pressure in the first hydraulic cylinder when contracting or extending the second hydraulic cylinder in a condition in which the first hydraulic cylinder is contracted.