Changes in switching function on directional control valves
The path of compressed air in pneumatics is controlled using directional control valves. They can for example control whether a double-acting cylinder retracts or extends, or whether a compressed air line is supplied with air or exhausted.
On many directional control valves, a small conversion or sealing of the supply ports can, if required, cause a change in switching function.
The options on the solenoid valve series CPE (Compact Performance) are explained in more detail below:
So a CPE valve with 5/2-way function can be converted into a valve with 3/2-way function.
This is done simply by screwing a blanking plug into one of the two working lines (port 2 or 4). It is even possible to create a valve with 2/2-way function using a 5/2-way valve. To do this, all unrequired supply ports are closed off with blanking plugs.
However, a 3/2-way valve from the CPE series cannot be converted into a 2/2-way valve. The switching function could no longer be guaranteed due to identical piston surfaces on the control piston.
Another function variant - mainly with 3/2-way valves – is the use as pressure-vacuum shunt. A vacuum or pressure is applied to ports 1 and 3
and then alternately switched through to port 2. To do this, a 3/2-way valve with external auxiliary pilot air is required.
For example, the connection for a solenoid valve from the Tiger series (MFH-5-…-S) is described below:
Reliable functioning of the valve in the vacuum range is only guaranteed if the vacuum is connected to port 1. The (positive) pressure is connected to port 3. Now it is possible to switch between pressure and vacuum. If only a vacuum should be switched, port 3 must still remain open and should not be closed off with a blanking plug.