Hydraulic Actuator Shuttle Valve Pressure Balancing
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Solution Overview
Problem
Existing electro-hydraulic actuators and control valves face challenges in efficiently managing hydraulic fluid pressure and flow, particularly in maintaining equilibrium and controlling movement under varying loads and conditions such as thermal expansion and shock loading, while ensuring reliable operation and minimizing friction and pressure imbalances.
Innovation Solution
A control valve design featuring a shuttle with spring-biased non-return valves and a centralizing spring, along with an accumulator and bypass valves, allows for controlled hydraulic flow and return, accommodating piston rod effects and thermal expansion, and enabling independent actuation of a double-acting hydraulic device with a reversible flow-and-return source of hydraulic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex manifold with multiple ports and conduits is used to manage hydraulic flow, then flow control capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple control functions (flow control, pressure balancing, non-return valve actuation) into a single integrated control valve body. The shuttle mechanism simultaneously controls flow paths and actuates both non-return valves, eliminating the need for separate manifolds and reducing overall system complexity while maintaining full flow control capability.
Solution Approach 2:
The control valve performs multiple functions through a single device: it directs hydraulic flow to either side of the actuator, balances pressure between supply conduits, actuates non-return valves through the shuttle mechanism, and provides volumetric compensation. This multi-functionality replaces what would otherwise require multiple separate components.
2Reliability
If spring-biased non-return valves are used to maintain pressure, then pressure retention is improved, but force requirements increase
Solution Approach 1:
The shuttle acts as an intermediary mechanism that uses balanced hydraulic pressure from either side to actuate the non-return valves. When pressure builds on one side, the shuttle moves and mechanically opens the corresponding non-return valve, distributing the force requirement across the hydraulic system rather than requiring a single high-force actuator.
Solution Approach 2:
The non-return valves transition from a static spring-biased system to a dynamic system where the shuttle position responds to pressure differential. The valves open automatically when hydraulic pressure overcomes the spring force, and the shuttle's movement provides mechanical assistance to overcome the spring bias, reducing the net force requirement from the primary hydraulic source.
3Measurement precision
If a shuttle valve with spring bias is used to centralize flow, then flow control precision is improved, but friction losses increase
Solution Approach 1:
The patent uses hydraulic pressure from the system itself to actuate the shuttle and overcome spring bias, rather than relying solely on mechanical friction between the shuttle and valve body. The hydraulic force acts on the shuttle surface area, providing a more efficient means of movement that reduces reliance on friction-based mechanical contact.
4Stability of the object's composition
If multiple valves and springs are used for pressure balancing, then pressure equilibrium is improved, but device complexity increases
Solution Approach 1:
The control valve body integrates the shuttle mechanism, spring elements, non-return valve actuation, and flow path control into a single compact unit. This consolidation achieves pressure balancing and flow control functions without requiring multiple separate valves and assemblies, reducing overall device complexity while maintaining pressure equilibrium.
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 solution ensures stable and controlled movement of the actuator by maintaining pressure equilibrium, reducing friction, and accommodating load variations, thus enhancing the reliability and efficiency of the electro-hydraulic actuator system.
Implementation Method 1
two respective non-return valves, having closure members resiliently biased into seats, and arranged on either side of the shuttle to allow pressure flow to a respective end inlet of the actuating device from the respective point of the source
Implementation Method 2
springs on either side of the shuttle to centre it with respect to the non-return valves and closure-member movers extending in either direction from the shuttle for acting on the respective closure members to move them mechanically off their seats
Implementation Method 3
the springs being of such stiffness that the shuttle moves from its central position only after pressure has risen at one side above that required for hydraulic opening of this side non-return valve such that the shuttle then moves off-centre
Data Source
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AI summary
A double-acting actuating device (1) has a cylinder (2) with a piston (3) connected to a rod (4). The cylinder is provided with ports (8, 9) at opposite ends for flow/return lines (10, 11) to provide flow of hydraulic liquid to whichever side of the piston is to be pressurised for its movement and to provide return of hydraulic liquid from the other side. The lines (10, 11) pass to opposite ends of a shuttle valve (20) having a body (21) with a bore (22) accommodating a double acting piston (23) having short rods (24, 25) extending on either side. Each rod carries a centring spring (26, 27) acting against its face of the shuttle piston and an end fitting (28, 29) of the body. The springs are relatively stiff and centralise the shuttle. The fittings seal the bore, except that each has a central drilling (30) which can freely accommodate the rod on its side of the piston and allow hydraulic liquid flow at the same time. Outwards of the drilling, each fitting has a tapered bore (31) for receiving a non-return valve ball (32) held against the bore (31) by a spring (33). The bore has two ports (35, 36) respectively close to the end fittings (28, 29). The body (21) of the shuttle valve has two ports (61, 62), opening into the bore (22) adjacent the end fittings (28, 29), to which ports are connected flow and return lines (63, 64) from a reversible gear pump (65), selectively driven in either direction by an electric motor (66). In normal operation, the pump is driven in the direction required for the desired movement of the actuator, as a whole. Flow of hydraulic liquid is to one end of the shuttle valve. The pressure of the liquid lifts the valve in the respective end fitting (28, 29). Pressure is applied to the actuating device and via its piston to the liquid in the respective line back to the other of the fittings. Until the valve in this fitting is opened no movement can occur. The pressure acts on the shuttle, moving it towards this valve, which it opens via its rod (24, 25), the effective area of the balls (33) seating in their tapers (31) being less than that of the shuttle piston. Movement can then occur with the return of liquid back to the pump and piston rod effect flow to or from the accumulator via the line (75).