Eaton’s Vickers HFV (Hydraulic Feedback Valvistor) range of slip-in cartridge valves uses a self-regulating hydraulic design for the control of flow rate by a current-controlled PWM signal. The design achieves servo-type control of the main poppet without using an electrical feedback transducer.
The construction and features of these valves open up a wide range of applications with hydraulic cylinders and motors. Such applications include ie casting, deep drawn presses, injection molding, container handling, shovel loaders, forestry and dump trucks. With the addition of HFV valves to the established ISO 7368 (DIN 24342) cartridge valves, Eaton has further enhanced an already comprehensive range.
In Valvistor designs a main poppet amplifies a small flow through the pilot circuit, comparable to a transistor. Thus the name Valvistor, derived from valve and transistor. In both cases a Vickers type KTG4V-3S proportional valve is used as the pilot control valve. KBTG4V3S-EN427 & KBFTG4V-3SEN427 can also be used as pilot valves. Hydraulic position feedback is obtained by providing the main poppet with a longitudinal slot (5) in its cylindrical surface. This slot, together with a metering edge inside the sleeve, forms a variable orifice between the inlet of the valve and the volume above the main poppet (3). When the valve is closed and the main poppet is seated, the variable orifice area is almost closed.
Maximum Operating Pressure: 350 bar (5000 psi)
Flow Ratings: Up to 2160 Lpm (571 USgpm)
These cartridge valves are integral assemblies of cover and insert with a main spool that is fully seated in its closed position. A coaxially mounted switch on the top cover provides a signal when the main spool is in position to close the mainstream flow.
On all models a spring holds the main spool in the closed position, requiring a small pressure to create flow through the valve. Pilot pressure from either a remote source (SWD models), or from a valve mounted directly onto the cover (SWD3 models) can be used to hold the spool fully closed. The Dynamic models, ZSWD3, with pilot operation of both opening and closing, cater for applications requiring fast response.
Flow can be in either direction (i.e. A to B, and B to A). The SWD(3) range is specifically designed for application in circuits and systems where electrical signalling of a known (closed) condition of the valve is required. The design of the main spool ensures that both switch indications, i.e. valve closed and valve open, occur when the valve is closed to mainstream flow.