Diagonal fan

Abstract

A diagonal ventilating fan ( 30 ) has a fan housing ( 36 ) and a fan wheel ( 80 ), rotatable around a rotation axis, that has associated with it an electric motor ( 73 ) to drive it, the fan wheel ( 80 ) extending in the direction of the rotation axis between an air inlet side and an air outlet side of the diagonal ventilating fan ( 30 ) and serving, as it rotates, to convey air in a main delivery direction from the air inlet side to the air outlet side. The fan wheel ( 80 ) has a preferred rotation direction so that, during operation, its blades ( 82 ) each have a front side and a back side, and a negative-pressure zone ( 110 ) occurs, during operation, adjacent each respective back side of a blade ( 82 ). An auxiliary cooling air blower ( 76 ) connects to the respective zones ( 110 ) to provide an improved flow of cooling air for the electric motor ( 73 ).

1 . A diagonal ventilating fan that comprises:
 a fan housing ( 36 );   a fan wheel ( 80 ), rotatable in a preferred direction about a rotation axis, that has associated with it an electric motor ( 73 ) to drive it, the fan wheel ( 80 ) extending, along the direction of the rotation axis, between an air inlet side and an air outlet side of the diagonal ventilating fan ( 30 ) and serving, as the fan wheel rotates, to convey air in a main delivery direction from the air inlet side to the air outlet side;   fan blades ( 82 ), provided on the outer side of the fan wheel ( 80 ) which each have, with reference to said rotation direction ( 84 ) of the fan wheel ( 80 ) during operation, a front side and a back side, such that, during operation, a respective negative-pressure zone ( 110 ) arises adjacent the back side of each blade ( 82 );   an auxiliary cooling air blower ( 76 ) which is configured to transport cooling air on an inner side of the fan wheel ( 80 ) from the air outlet side toward the air inlet side, and by that air flow, to cool the electric motor ( 73 ) of the diagonal ventilating fan ( 30 ); and   at least one fluid connection ( 114 ;  118 ;  130 ′) from the outlet of the auxiliary cooling air blower ( 76 ) to at least one of the negative-pressure zones ( 110 ) in order to assist a flow ( 126 ;  126 ′) of motor-cooling air, occurring from the air outlet side of the diagonal ventilating fan ( 30 ) toward the air inlet side thereof.   
     
     
         2 . The diagonal ventilating fan according to  claim 1 , in which
 the fan wheel ( 80 ) comprises, on the air outlet side of the diagonal ventilating fan ( 30 ), a first annular portion ( 94 ) that interacts with a second annular portion ( 48 ), located opposite it, of a stationary part ( 44 ) of the diagonal ventilating fan ( 30 ), said second annular portion ( 48 ) being located oppositely to the first annular portion ( 94 ),   air-directing elements ( 50 ) being provided on this second portion ( 48 ), said air-directing elements ( 50 ) acting, during operation, as a brake for air that is entrained by a rotation of said first portion ( 94 ).   
     
     
         3 . The diagonal ventilating fan according to  claim 1  wherein
 the fluid connection ( 114 ,  118 ) extends from the outlet of the auxiliary cooling air blower ( 76 ), through the inner side of the fan wheel ( 80 ) and through at least one opening ( 90 ) provided in the fan wheel ( 80 ), to a negative-pressure zone ( 110 ) arising adjacent the fan wheel ( 80 ). 
 
     
     
         4 . The diagonal ventilating fan according to  claim 1 , wherein
 the auxiliary cooling air blower ( 76 ) comprises a connecting member ( 130 ) that extends over the outer side of fan wheel ( 80 ) as far as a negative-pressure zone ( 110 ) occurring at the fan wheel during operation, so that the pressure of that negative-pressure zone ( 110 ) becomes effective at an outlet of the auxiliary blower ( 76 ).   
     
     
         5 . The diagonal ventilating fan according to  claim 3 , wherein the inner side of the fan wheel ( 80 ) is divided into
 a first space ( 120 ) in which, during operation, substantially the pressure (P 2 ) at the air outlet of the diagonal ventilating fan pertains, and   a second space ( 118 ) that is connected via at least one opening ( 90 ) of the fan wheel ( 80 ) to the outer side of the fan wheel.   
     
     
         6 . The diagonal ventilating fan according to  claim 5 , wherein
 at least one opening ( 90 ) is arranged in a zone ( 110 ) of reduced pressure arising on the back side of a fan blade ( 82 ), said back side being defined with reference to the rotation direction ( 84 ) of the fan wheel ( 80 ).   
     
     
         7 . The diagonal ventilating fan according to  claim 5  wherein
 a separating member ( 116 ), which extends between the inner side of the fan wheel ( 80 ) and the rotor ( 76 ) of the electric drive motor ( 73 ), is provided between the first space ( 120 ) and the second space ( 118 ). 
 
     
     
         8 . The diagonal ventilating fan according to  claim 7 , in which the electric motor ( 73 ) is implemented as an electronically commutated external-rotor motor. 
     
     
         9 . The diagonal ventilating fan according to  claim 1 , wherein
 an air guidance system defined in the fan wheel ( 80 ) is sealed against leaks, and the openings ( 90 ) on the back side of the fan blades ( 82 ) are at a greater radial distance from the rotation axis of the ventilating fan ( 30 ) than are the inlet openings.