Flow Control Valve Spool for Construction Machines
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Solution Overview
Problem
Existing flow control valves for construction machines fail to consistently control the flow rate of hydraulic fluid supplied to hydraulic actuators, as it varies with pressure generated in the hydraulic pump and actuator, and changes in the supplied flow rate.
Innovation Solution
A flow control valve with a spool that variably controls the cross-sectional area of passages connected to actuator ports, using a flow control spool with multiple passages and signal pressure passages to maintain a constant flow rate by adjusting the cross-sectional area based on flow rate and pressure conditions, ensuring hydraulic fluid is supplied at a set flow rate regardless of pump and actuator pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spool is used to control hydraulic fluid flow, then the flow rate varies with pressure changes in the hydraulic pump and actuator, but the structure remains simple
Solution Approach 1:
The spool is designed with a variable cross-sectional area passage that dynamically adjusts the flow area based on pressure conditions. The passage cross-sectional area changes along the length of the spool, allowing the flow rate to be compensated for pressure variations automatically, thereby maintaining consistent flow delivery to the actuator.
Solution Approach 2:
The invention changes the geometric parameter of the passage cross-sectional area along the spool length. By varying the cross-sectional area from the inlet end to the outlet end, the valve compensates for pressure-induced flow variations, ensuring reliable and consistent flow rate control despite pressure fluctuations in the hydraulic system.
2Reliability
If additional flow control components are added to maintain constant flow rate, then flow rate control improves, but installation space and manufacturing cost increase
Solution Approach 1:
The flow control function is merged into the spool structure itself. Instead of adding separate flow control valves or components, the spool is designed with an integrated variable cross-sectional area passage that performs both the switching and flow control functions, eliminating the need for additional components and reducing installation space.
Solution Approach 2:
The spool serves multiple functions: it acts as both a switching element to direct hydraulic fluid flow and as a flow control element through its variable cross-sectional area passage. This multi-functionality eliminates the need for separate flow control devices, reducing overall system complexity and installation space requirements.
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 allows for constant flow rate control without the need for additional installation space, reducing manufacturing costs and enhancing equipment reliability by maintaining consistent flow rates despite variations in hydraulic pump and actuator pressures.
Implementation Method 1
a flow control spool (11) which is shifted in the spool (7) to fix the cross-sectional area of a passage (13) connected to the one actuator port (3) to a set value if pressure of the hydraulic fluid that flows through the supply passage (2) is higher than a set pressure
Data Source
AI summary
A flow control valve for a construction machine is provided, which can constantly control a flow rate of hydraulic fluid supplied to a hydraulic actuator through a flow control spool in a spool. The flow control valve for a construction machine, having a valve body in which a supply passage communicating with a pump passage and actuator ports connected to a hydraulic actuator are formed, and a spool installed in the valve body to be shifted, includes a flow control spool shifted in the spool to variably control a cross-sectional area of a passage connected to the one actuator port if a flow rate of the hydraulic fluid that flows through the supply passage is higher than a set flow rate, a first passage formed on the spool to communicate with the supply passage and a second passage formed on the spool to communication with the one actuator port and having a cross-sectional area that is varied depending on the shifting of the flow control spool.