Directional Control Valve Spool Return Using Short-Term Counter-Pressure
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Solution Overview
Problem
Hydraulic directional control valves face challenges in quickly positioning the main spool due to mass effects from flow forces and oil viscosity, leading to slow response times, which can impact safety and efficiency in systems like steer-by-wire and mining equipment.
Innovation Solution
A method and apparatus that accelerate the return motion of the main spool by counteracting pilot pressure on one end while releasing pressure on the other, using electronic control to apply a short-term counter-pressure, thereby reducing the time taken to return to a neutral position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional pilot valve control is used, then the valve structure is simple, but the response time is slow due to mass effects from flow forces and oil viscosity
Solution Approach 1:
The patent applies counter-pressure to the second end of the spool to counterbalance the mass effects and flow forces acting on the spool. This counteracting force compensates for the inertia and viscous drag that slow down spool movement, enabling faster response times without changing the fundamental valve structure.
Solution Approach 2:
The control system applies counter-pressure in advance during the spool return motion, particularly when the spool is moving from an actuated position toward neutral. This preliminary application of counter-pressure accelerates the spool before it reaches the neutral position, reducing the overall response time.
2Speed
If spring bias alone is used to return the spool to neutral position, then the valve structure is simple, but the return motion is slow due to oil viscosity and flow forces
Solution Approach 1:
Counter-pressure is applied to the second end of the spool to counterbalance the retarding forces of oil viscosity and flow resistance during return motion. This creates a net force that accelerates the spool back to neutral position faster than spring bias alone could achieve.
Solution Approach 2:
The counter-pressure is applied periodically or in pulses during specific phases of spool motion, particularly during the return stroke. This timed application of force optimizes the acceleration effect while maintaining relatively simple control logic.
3Loss of time
If counter-pressure is applied to accelerate spool return, then the response time is reduced, but the control system complexity increases
Solution Approach 1:
The electronic control system monitors spool position and applies counter-pressure based on feedback signals. This closed-loop control ensures that counter-pressure is applied at the optimal moments to accelerate spool return without causing overshoot or instability, managing the complexity through intelligent control rather than mechanical complexity.
Solution Approach 2:
The control system acts as an intermediary between the pilot valve and the spool, mediating the force application timing and magnitude. This electronic intermediary optimizes the interaction between hydraulic forces and spool motion, achieving fast response with relatively simple added control electronics.
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 approach significantly reduces the time for the main spool to return to a neutral position, enhancing responsiveness and reducing wear in safety-critical and high-precision applications.
Implementation Method 1
applying a short-term counter-pressure or counter-force acting on a second longitudinal end of the main spool for providing an accelerated return motion
Implementation Method 2
the ability to move a certain amount of mass that is affected by flow forces and oil viscosity
Data Source
Figure 1~2
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Figure 5~6
AI summary
A method for accelerating return motion of a main spool (50) of a hydraulic directional control valve (10) towards a spring-biased neutral position of the main spool (50). The method comprising reducing or stopping a control pressure or control force acting on a first longitudinal end of the main spool (50), and substantially simultaneously applying a short-term counter-pressure or counter-force acting on a second longitudinal end (60) of the main spool (50) for providing an accelerated return motion of the main spool (50) towards the spring-biased neutral position of the main spool (50). The disclosure also relates to a corresponding hydraulic valve arrangement and computer-implemented method.