Electrically controlled three-way valve

Abstract

An electrically controlled three-way valve comprising a valve body, within which a central cavity and a respective first, second and third connection duct, adapted to bring the central cavity into communication with atmosphere, are provided, and a shutter member mounted to move within the central cavity between a first operating position, in which the shutter member is disposed to close the inlet of the first duct so as to obstruct this first duct in a leak-tight manner and to bring the second duct into sole communication with the third duct, and a second operating position in which the shutter member is disposed to close the inlet of the third duct in order to obstruct this third duct in a leak-tight manner and to bring the second duct into sole communication with the first duct; the shutter member being of spherical shape and independent from any other member of the valve so that it can move freely within the central cavity; the central cavity being shaped such that the shutter member is forced simultaneously to engage the inlets of the first and the third connection ducts, but obstructs, however, only one of the first and third connection ducts in a leak-tight manner.

1 . An electrically controlled three-way valve ( 1 ) comprising a valve body ( 2 ), within which a central cavity ( 3 ) and a respective first, second and third connection duct ( 4 ,  5 ,  6 ), adapted to bring the central cavity ( 3 ) into communication with atmosphere, are provided, and a shutter member ( 7 ) which is mounted to move within the central cavity ( 3 ) between a first operating position, in which the shutter member ( 7 ) is disposed to close the inlet of the first duct ( 4 ) so as to obstruct this first duct ( 4 ) in a leak-tight manner and to bring the second duct ( 5 ) into sole communication with the third duct ( 6 ), and a second operating position in which the shutter member ( 7 ) is disposed to close the inlet of the third duct ( 6 ) in order to obstruct this third duct ( 6 ) in a leak-tight manner and to bring the second duct ( 5 ) into sole communication with the first duct ( 4 ), the three-way valve ( 1 ) being characterised in that the shutter member ( 7 ) is independent from any other member of the valve ( 1 ) and is mounted to move freely within the central cavity ( 3 ), and in that the central cavity ( 3 ) is shaped such that the shutter member ( 7 ) is forced simultaneously to engage the inlets ( 4   a ,  6   a ) of the first and the third connection ducts ( 4 ,  6 ), but obstructs, however, only one of the first and third connection ducts ( 4 ,  6 ) in a leak-tight manner.  
     
     
         2 . A three-way valve as claimed in  claim 1 , characterised in that the inlet ( 4   a ) of the first connection duct ( 4 ) and the inlet ( 6   a ) of the third connection duct ( 6 ) face the central cavity ( 3 ) on opposite sides of the shutter member ( 7 ), the valve ( 1 ) further comprising a retractile pressure member ( 8 ) which is adapted to project, on command, within the central cavity ( 3 ) through the inlet ( 6   a ) of the third connection duct ( 6 ) in order to be disposed in abutment on the shutter member ( 7 ) so as to urge it into abutment against the inlet ( 4   a ) of the first connection duct ( 4 ) so as close it in a leak-tight manner.  
     
     
         3 . A three-way valve as claimed in  claim 1 , characterised in that the inlet ( 4   a ) of the first connection duct ( 4 ) is formed by a flared surface ( 4   a ) on which the shutter member ( 7 ) is adapted to be disposed in abutment, partially engaging the space inside this flared surface ( 4   a ).  
     
     
         4 . A three-way valve as claimed in  claim 1 , characterised in that the inlet ( 6   a ) of the third connection duct ( 6 ) is formed by a flared surface ( 6   a ) on which the shutter member ( 7 ) is adapted to be disposed in abutment, partially engaging the space inside this flared surface ( 6   a ).  
     
     
         5 . A three-way valve as claimed in  claim 1 , characterised in that the shutter member ( 7 ) is substantially spherical in shape.  
     
     
         6 . A three-way valve as claimed in  claim 6 , characterised in that the central cavity ( 3 ) is shaped such that the distance (d) between the outer peripheral edge of the inlet ( 4   a ) of the first duct ( 4 ) and the outer peripheral edge of the inlet ( 6   a ) of the third duct ( 6 ) is smaller than the diameter of the shutter member ( 7 ).  
     
     
         7 . A three-way valve as claimed in  claim 2 , characterised in that the retractile pressure member ( 8 ) comprises a rod or strut ( 8 ) which is positioned immediately downstream of the inlet ( 6   a ) of the third duct ( 6 ) and is able to perform, on command, an axial displacement towards the interior of the central cavity ( 3 ) so as temporarily to project inside the central cavity ( 3 ) with its point disposed in abutment on the shutter member ( 7 ).  
     
     
         8 . A three-way valve as claimed in  claim 1 , characterised in that the valve body ( 2 ) comprises an elongate tubular member ( 10 ) having a through duct ( 10   a ) which extends over the entire length of this tubular member ( 2 ), and a closure cap ( 11 ) secured in a non-detachable manner to an axial end of the elongate tubular member ( 10 ) so as to close the through duct ( 10   a ) in a leak-tight manner, the central cavity ( 3 ) and the first, second and third connection ducts ( 4 ,  5 ,  6 ) being provided within the closure cap ( 11 ) such that the central cavity ( 3 ) and the first and the third ducts ( 4 ,  6 ) are coaxial with the longitudinal axis (A) of the elongate tubular member ( 10 ), with the first duct ( 4 ) facing outwards and the third duct ( 6 ) facing, and in direct communication with, the through duct ( 10   a ) of the elongate tubular member ( 10 ).  
     
     
         9 . A three-way valve as claimed in  claim 8 , characterised in that retractile pressure member ( 8 ) is mounted in an axially moving manner within the through duct ( 10   a ) of the elongate tubular member ( 10 ).  
     
     
         10 . A three-way valve as claimed in  claim 2 , characterised in that the retractile pressure member ( 8 ) moves axially under the effect of elastic and electromagnetic forces.  
     
     
         11 . A three-way valve as claimed in  claim 10 , characterised in that the retractile pressure member ( 8 ) comprises a bushing ( 12 ) of ferromagnetic material mounted to move axially within the through duct ( 10   a ) and a needle or pin ( 13 ) extending in a projecting manner from the bushing ( 6 ) to the closure cap ( 11 ) coaxially with the longitudinal axis (A) of the elongate tubular member ( 10 ).