Patent ID: 6513174
Filing Date: 2003-02-04
Classification: E03F

Abstract:
A vacuum unit that comprisesa first valve (4) that can be connected to a compressed-air source (32) and that has a first, closed position and a second, open position; a second valve (6) that can be connected to a compressed-air source (32); an ejector (10) that includes an inlet nozzle (10a), an outlet nozzle (10b), and a vacuum opening (10c), wherein the ejector is connected to the first valve (4) via the inlet nozzle, and to a first connection (U1) of said vacuum (2) via said vacuum opening; and a piston valve (16) that has a first inlet (16a), a second inlet (16b) and an outlet (16c), wherein said piston valve has an open position in which the outlet (16c) connects with the first inlet (16a), and a closed position in which the outlet (16c) is not connected to the first inlet (16a) or the second inlet (16b), and with which piston valve (16) the first inlet is connected to the outlet nozzle (10b) of the ejector, the second inlet is connected to the second valve (6), and the outlet is connected to a second connection (U2) of said vacuum unit, said vacuum unit being characterised in that the second valve (6) has a first position in which the second inlet (16b) of the piston valve (16) connects with the surroundings, and a second position in which the second inlet (16b) of the piston valve (16) connects with the compressed-air source; wherein the piston valve (16) is adjusted to an open position with the second valve (16) in its first position, whereby an open position of the first valve (4) causes a sub-pressure to be generated in the vacuum opening; and wherein the piston valve (16) is adjusted to a closed position with the second valve (6) in its second position, whereby opening of the first valve (4) causes an overpressure to be generated in the vacuum opening.