Stick Cylinder Hydraulic Circuit for Independent Flow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hydraulic control circuits for construction machines, such as hydraulic excavators, face challenges in accurately controlling flow rates for stick cylinders due to the configuration of spool valves and pumps, leading to inefficiencies and increased costs, particularly when recycling hydraulic oil.
Innovation Solution
The implementation of a hydraulic control circuit with poppet valves and stick spool valves that control supply, recycle, and discharge flow rates independently for the stick cylinder, allowing for precise flow rate management without altering the flow rate from the poppet valves, and the use of bypass valves to manage delivery flow rates from hydraulic pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single spool valve is used to control both supply flow rate and discharge flow rate for the stick cylinder, then the valve structure is simple, but the flow rate control precision deteriorates
Solution Approach 1:
The patent divides the flow control function into two separate spool valves: a first spool valve (18) dedicated to controlling supply flow rate from the hydraulic pump to the stick cylinder, and a second spool valve (19) dedicated to controlling discharge flow rate from the stick cylinder to the hydraulic pump. This segmentation allows each valve to independently control one flow rate parameter with high precision, resolving the contradiction between structural simplicity and control precision.
2Ease of operation
If spool valve opening areas are uniquely determined by valve position, then the control mechanism is simple, but the adaptability to different work contents deteriorates
Solution Approach 1:
The patent introduces dynamic control capability through poppet valves (20, 52) positioned upstream of each spool valve. These poppet valves can dynamically adjust the opening areas of the spool valves based on detected work content (stand-alone work, compound work, light load, heavy load), enabling the system to adapt to different operational requirements while maintaining simple spool valve mechanics. The control unit dynamically modifies valve openings to optimize performance for each work scenario.
3Adaptability or versatility
If control valves are installed upstream of spool valves to change pressure oil supply amount, then the adaptability to different work contents is improved, but the control complexity increases
Solution Approach 1:
The patent uses poppet valves (20, 52) as intermediary devices positioned upstream of the main spool valves. These poppet valves act as mediators that receive control signals from the control unit and adjust the opening areas of the downstream spool valves accordingly. This intermediary approach enables flexible adaptation to different work contents while keeping the main spool valve structure relatively simple, as the poppet valves handle the dynamic adjustment function.
4Measurement precision
If flow control valve and direction change-over valve are provided separately, then the flow rate control precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges the flow control valve function and direction change-over valve function into a single integrated spool valve structure. Each spool valve simultaneously performs both functions: controlling flow rate through its opening area and directing hydraulic oil flow through its spool position. This merging reduces device complexity while maintaining flow rate control precision, as the spool valve's geometric design enables both control functions within a single component.
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 configuration enables high efficiency and improved operability by allowing independent control of supply, recycle, and discharge flow rates for the stick cylinder, reducing operational complexity and costs, and ensuring stable operation even during impossible recycling conditions.
Implementation Method 1
a poppet valve is provided at upstream side of the first spool valve for controlling a supply flow rate from the first hydraulic pump to the first stick spool valve
Implementation Method 2
the first stick spool valve is configured to supply hydraulic flow to the stick cylinder without increasing or decreasing a flow rate from the poppet valve, and when the stick cylinder is extended, the poppet valve is configured to control supply flow rate from first hydraulic pump to head side oil chamber of the stick cylinder, the first stick spool valve is configured to control a recycled flow rate from rod side oil chamber of the stick cylinder to the head side oil chamber
Implementation Method 3
the second stick spool valve is configured to control supply flow rate from second hydraulic pump to head side oil chamber of the stick cylinder and discharge flow rate from rod side oil chamber to an oil tank
Implementation Method 4
first and second hydraulic pumps configured to swing the stick in dependence upon extension and contraction operations of a stick cylinder and used as hydraulic supply source
Data Source
AI summary
To make it possible to control supply, discharge, and recycled flow rates independently of each other for the stick cylinder in a construction machine comprising first and second stick spool valves respectively connected to first and second hydraulic pumps. [Solution] A poppet valve is provided at upstream side of the first stick spool valve for controlling a supply flow rate from first hydraulic pump, the first stick spool valve is configured to supply hydraulic flow from the poppet valve to the stick cylinder without restricting the flow, and when the stick cylinder is extended, the poppet valve is configured to control supply flow rate from the first hydraulic pump to head side oil chamber, the first stick spool valve is configured to control recycled flow rate from a rod side oil chamber to the head side oil chamber, and the second stick spool valve is configured to control the supply flow rate from second hydraulic pump to head side oil chamber and the discharge flow rate from the rod side oil chamber to an oil tank.