Camozzi Pneumatics Manual

VALVES

Solenoid valves with internal servo pilot

As a result of demand from themarket for componentswith reduced dimensions and low power consumption, the

solenoid valvesmust be equippedwith the smallest possible solenoids with reduced power consumption. In these

cases, the solenoid is not actingdirectly on the switching, but on opening or closing the power supply to the control

piston as analyzed in the

“Types of pneumatic activation in valves”

The solenoid group can vary in shape, type of electrical connection or regulations, and matches the end covers

that contain the previously mentioned control piston. The air supply to the solenoid is the same as that supplied

to the main valve and is obtained via an internal channel inside the valve. This feature defines the valve as the

servo valvewith internal pilot

Figure 32

Solenoid valvewith dual electric command

The central body is that of a normal spool valve inwhich there is internal channeling of the servo-pilot. The ends

of the body are closed by end covers that integrate the solenoids. Themain air supply from inlet 1 also powers the

solenoids, their respective output drives the pilot pistons.

The solenoid on the right is energized; the outgoing air moves the pilot piston whichmoves the spool to the left.

In this phase, the solenoid on the left shouldnot be energized.When removing the electrical signal to the solenoid,

the solenoid valve holds the position. This solenoid valve is called Bistablewith internal servo pilot.

Fig. 32

Figure 33

Solenoid valvewith electric command and spring return (monostable valve)

In this situation, the solenoid to the right has been replaced by a mechanical spring. The solenoid on the left is

energized, the pilot air moves the pilot piston, which moves the spool to the right, and compresses the return

spring.When releasing the electrical signal from the solenoid, the solenoid valve returns to its rest position due to

the thrust of the spring.With the solenoid no longer energized, the solenoid valve assumes the position defined by

the spring. This solenoid valve is called aMonostable valvewithmechanical spring return and internal servo pilot.

Fig. 33

Figure 34

Solenoid valvewith electric command and pneumatic spring return

Unlike the previous case a pneumatic rather thanmechanical spring is used. The pneumatic spring is made by a

piston, still pressurized, but smaller than the spring on the end capwith the solenoid.

When the solenoid is not energized and in the presence of compressed air, the solenoid valve assumes the position

determinedby the pneumatic spring. This solenoid valve is calledaMonostable valvewithpneumatic spring return

and internal servo pilot.

Fig. 34

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CAMOZZI

VALVES