Patent ID: 7762520

Claim:
A servo valve for a vacuum system comprising: a housing defining a control chamber and a valve passage having a fluid intake part with a first pressure and a fluid outlet part with a second pressure, the parts being separated by a closure member mounted in the housing for movement between an open and a closed position under influence of a difference between a control pressure of the control chamber and the first and second pressures, the open position being a position wherein the valve passage is open between the intake part and the outlet part and the closed position being a position wherein the valve passage is closed between the intake part and the outlet part, the control chamber being in fluid communication with the intake part via a constantly open passage and being in controllable fluid communication with the outlet part via a pilot passage, being closable by a pilot closure member which is movable relative to the closure member between an open position wherein the pilot passage is open and a closed position wherein the pilot passage is closed to influence the control pressure mainly by one of the first pressure and the second pressure depending on the position of the pilot closure member, and thereby for controlling movement of the closure member between its closed and its open position, the pilot closure member being fastened to the closure member via an elastically deformable coupling, wherein the pilot closure member is biased towards its closed position by an elastically compressible member acting between the housing and the pilot closure member; and wherein the closure member is shaped as a piston and arranged to move back and fourth in a cylindrical cavity of the housing; and wherein the closure member and the cylindrical cavity have circular cross-sectional matching shapes, and wherein the constantly open passage is formed between a sidewall of the closure member and an inner sidewall of the cylindrical cavity.