Advantages of Proportional Directional control valves when compared with ordinary “Bang-Bang” Directional Control valves

Directional control valves (DCV) are one of the most fundamental parts in hydraulic system. They allow fluid flow into different paths from one or more sources. They usually consist of a spool inside a cylinder which is mechanically or electrically controlled. The movement of the spool restricts or permits the flow, thus it controls the fluid flow.

But in a proportional valve it allow infinite positioning of spools, thus providing infinitely adjustable flow volumes. Either stroke-controlled or force-controlled solenoids are used to achieve the infinite positioning of spools.

An advantage of Proportional control valves when compared with ordinary “Bang-Bang” Directional Control valves are as follows.

  • Smoother operation of the system because the rate of opening and closing of the valve can be controlled by the amplifier. Self-switching conventional valves are available but they are difficult to setup and can give consistent performance.
  • The reduction of shock in the system can extend the life of hydraulic components, seals, coolers and filters, improve machine performance and product quality, reduce operator fatigue(noise, vibration and harshness)
  • Valves can be positioned for optimum hydraulic performance without regard to access for manual adjustment. This can also simplify machine design because of the removal of access restrictions
  • In proportional valves hydraulic remote control is possible, the use of proportional valves does away with the need to run high pressure hydraulic lines to the operators control station
  • Valves can be continuously adjusted during the machine cycle allowing flow or pressure to be precisely matched to the process requirements. This can significantly simplify that would otherwise have to use multiple (fixed setting) valves with selection via solenoid or cam operated valves
  • Accuracy and reputability of the total system can be improved by the use of electrical feedback transducers (position, force, velocity, flowetc.)and the signal to proportional valve can be automatically adjusted (closed loop control)
  • In the systems with computer controlled sequencing, setup times and commissioning times can be reduced on repeat installations because the same control program can be employed repeatedly

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