Balancing Spool Valve Assembly for Hydraulic Oscillation Control
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Solution Overview
Problem
Hydraulic machines, such as wheel loaders and skid steers, experience oscillations when operating on uneven terrain, leading to discomfort for operators, potential spillage, and reduced efficiency, as existing systems lack effective oscillation control mechanisms.
Innovation Solution
A valve assembly and hydraulic system that includes a main spool and balancing spool within a housing, allowing fluid coupling between an accumulator, a source, a reservoir, a head-side chamber, and a rod-side chamber, with the main spool moving between unactuated, first, and second axial positions to balance pressure levels and control fluid flow, thereby dampening oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hydraulic machine operates on uneven terrain, then the machine can perform operations in challenging environments, but oscillations occur causing operator discomfort and potential spillage
Solution Approach 1:
The valve assembly acts as an intermediary between the hydraulic actuator and the hydraulic fluid. It introduces a controlled fluid path that allows gradual compression of the accumulator, which serves as a mediator to absorb oscillations. The valve assembly includes a spool that controls fluid flow to the accumulator, creating a damping effect that reduces oscillations transmitted to the hydraulic actuator, thereby eliminating the harmful vibrations and spills while maintaining operational capability on uneven terrain.
2Object-affected harmful factors
If oscillation control mechanisms are added to hydraulic systems, then oscillations can be reduced, but system complexity increases
Solution Approach 1:
The valve assembly merges the oscillation control function with the existing hydraulic system components. The spool is integrated into the valve body and works in conjunction with the accumulator that is already part of the hydraulic system. The fluid passage connects the valve assembly directly to the accumulator, combining multiple functions (flow control, pressure regulation, and oscillation damping) into a single integrated assembly, thereby reducing overall system complexity while achieving effective oscillation control.
3Object-affected harmful factors
If traditional oscillation control systems are implemented, then oscillation control is achieved, but cost and system efficiency decrease
Solution Approach 1:
The valve assembly utilizes the existing hydraulic fluid and accumulator pressure to control the spool position and regulate fluid flow. The system self-regulates by using the hydraulic pressure differential to automatically control the damping action, eliminating the need for external power sources, sensors, or complex control electronics. This self-service approach reduces cost while maintaining efficiency by leveraging the inherent properties of the hydraulic system itself.
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
The system effectively dampens oscillations, preventing unintentional movement of hydraulic actuators, reducing operator discomfort, and allowing for higher operating speeds while preventing material spillage, all while being cost-efficient by using a single solenoid valve to control both spools.
Implementation Method 1
the balancing spool is subjected to opposing fluid forces by fluid from the head fluid cavity and fluid from the accumulator fluid passage, thereby causing pressure level in the accumulator fluid passage to be balanced with pressure level in the head fluid cavity
Implementation Method 2
The system effectively dampens oscillations, preventing unintentional movement of hydraulic actuators
Data Source
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AI summary
An example valve assembly includes a housing having an accumulator fluid passage configured to be fluidly coupled to an accumulator, a supply fluid cavity configured to be fluidly coupled to a source of fluid, a reservoir fluid cavity configured to be fluidly coupled to a reservoir of fluid, a head fluid cavity configured to be fluidly coupled to a head-side chamber of a hydraulic actuator, and a rod fluid cavity configured to be fluidly coupled to a rod-side chamber of the hydraulic actuator; a main spool that is axially-movable within the housing; and a balancing spool that is axially-movable within the housing based on an axial position of the main spool.