Fluid Working Machine Valve Actuation for Low-Speed Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fluid working machines with two-stage valve assemblies face reliability issues with primary valve opening due to limited armature force, leading to uncontrollable shaft rotation and torque control challenges, especially at low speeds, which results in noise, wear, and inefficiency in transmission systems.
Innovation Solution
A method of operating a fluid working machine with a controllable opening mechanism that provides multiple active urging forces to the moveable valve member between maximum and minimum chamber volumes, enhancing reliability and control, and incorporating a pilot valve to equalize pressure and control fluid flow, thereby improving valve opening reliability and reducing shaft movement issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage valve assembly with a primary valve and secondary valve is used to regulate fluid flow, then the valve can control fluid flow between the working chamber and high pressure manifold, but the primary valve opening reliability deteriorates due to limited armature force
Solution Approach 1:
The secondary valve is opened in advance before the primary valve opening is attempted. This preliminary action equalizes the pressure across the primary valve member, reducing the force required to open the primary valve and thereby improving opening reliability despite limited armature force.
Solution Approach 2:
The secondary valve acts as an intermediary element that mediates the pressure distribution before the primary valve operation. By controlling fluid flow through the secondary valve first, the system prepares the pressure conditions necessary for reliable primary valve opening.
2Speed
If the primary valve opens rapidly to enable quick fluid flow regulation, then the response time is improved, but uncontrollable shaft rotation occurs leading to noise and wear
Solution Approach 1:
The valve opening process is divided into periodic stages: first the secondary valve opens to equalize pressure, then the primary valve opens. This staged periodic action controls the rate of fluid flow into the working chamber, preventing sudden shaft rotation while maintaining adequate response time.
Solution Approach 2:
The secondary valve provides a cushioning effect by gradually equalizing pressure before the primary valve opens. This beforehand cushioning prevents sudden pressure changes that would cause uncontrollable shaft rotation, noise, and wear.
3Measurement precision
If the high pressure manifold pressure is increased to improve torque control at low speeds, then the torque control precision is improved, but the energy consumption increases
Solution Approach 1:
The valve opening timing and duration are dynamically adjusted based on operating conditions. At low speeds, the secondary valve is opened longer or at higher pressures to achieve precise torque control, while at higher speeds the system operates more efficiently, adapting energy usage to actual operational needs.
Solution Approach 2:
The system changes operational parameters (valve opening timing, duration, and pressure) based on the operating mode. By adjusting these parameters dynamically, the system achieves precise torque control at low speeds without continuously maintaining high energy consumption levels.
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 results in a more reliable, controllable, and smooth operation of fluid working machines, reducing noise and wear, and enabling precise torque control at low speeds without the need for adjusting high pressure fluid source pressures, thus improving energy efficiency and system performance.
Implementation Method 1
a path is provided through the secondary valve for fluid to flow between opposite sides of the primary valve member to reduce the pressure difference across the primary valve member
Implementation Method 2
The primary valve comprises a face-seating primary valve member and a primary valve seat. The secondary valve is integral to the primary valve and includes a secondary valve member which is moveable between a sealing position and an open position
Data Source
AI summary
A fluid working machine comprises a working chamber of cyclically varying volume, a high pressure manifold, and an actuated high pressure valve for regulating the flow of fluid between the working chamber and the high pressure manifold. The actuated high pressure valve comprises a moveable valve member, operable between a closed position and at least one open position. A controllable opening mechanism provides an active urging force to urge the moveable valve member from the said closed position towards at least one said open position, the volume of the working chamber varying between a maximum volume and a minimum volume. The controllable opening mechanism provides the active urging force more than once while the volume of the working chamber is intermediate the maximum of chamber volume and the minimum of chamber volume.