Method for reducing noise of a cooking hood and a cooking hood based on such method

Abstract

A method and system for reducing noise of a cooking hood having a body containing a motor and a muffler mounted on an upper section of the body so as to be in fluid connection therewith. A motor active noise reduction unit produces motor reduction noise for reducing motor noise. Likewise, a muffler active noise reduction unit produces a muffler noise reduction signal for reducing muffler noise.

1 . A method for reducing noise of a cooking hood having a body containing a motor and a muffler mounted on an upper section of the body so as to be in fluid connection therewith, the method comprising: 
 providing or using in association with the motor a motor active noise reduction unit capable of producing a motor reduction noise for reducing motor noise; and    providing or using in association with the muffler a muffler active noise reduction unit capable of producing a muffler reduction noise for reducing muffler noise.    
     
     
         2 . The method according to  claim 1 , wherein the motor reduction noise is in the same amplitude and opposite phase to the motor noise.  
     
     
         3 . The method according to  claim 1 , wherein the muffler reduction noise is in the same amplitude and opposite phase to the muffler noise.  
     
     
         4 . The method according to  claim 1 , wherein the muffler active noise reduction unit is adapted to produce the muffler reduction noise by: 
 determining a component of the motor reduction noise reaching the muffler active noise reduction unit; and    adjusting the muffler active noise reduction unit so as to reduce an effective muffler noise corresponding to noise sensed by the muffler active noise reduction unit less said component of the motor reduction noise.    
     
     
         5 . The method according to  claim 4 , wherein the component of the motor reduction noise is predetermined.  
     
     
         6 . The method according to  claim 4 , wherein the component of the motor reduction noise is determined by a motor-muffler transfer function.  
     
     
         7 . The method according to  claim 5 , wherein the predetermined component of the motor reduction noise is measured offline.  
     
     
         8 . The method according to  claim 1 , wherein the motor active noise reduction unit and the muffler active noise reduction unit are mounted with sufficient mutual separation that interference between the motor active noise reduction unit and the muffler active noise reduction unit is negligible.  
     
     
         9 . The method according to  claim 1 , wherein the motor active noise reduction unit is adapted to produce the motor reduction noise by: 
 determining a component of the muffler reduction noise reaching the motor active noise reduction unit; and    adjusting the motor active noise reduction unit so as to reduce an effective motor noise corresponding to noise sensed by the motor active noise reduction unit less said component of the muffler reduction noise.    
     
     
         10 . The method according to  claim 9 , wherein the component of the muffler reduction noise is predetermined.  
     
     
         11 . The method according to  claim 9 , wherein the component of the muffler reduction noise is determined by a muffler-motor transfer function.  
     
     
         12 . The method according to  claim 10 , wherein the predetermined component of the muffler reduction noise is measured offline.  
     
     
         13 . The method according to  claim 1 , wherein the motor active noise reduction unit is adapted to produce the motor reduction noise by: 
 determining an emulated motor noise at an error point; and    adjusting the motor reduction noise to yield emulated motor reduction noise so as to reduce the emulated motor noise.    
     
     
         14 . The method according to  claim 13 , wherein the emulated motor noise is determined by a microphone transfer function.  
     
     
         15 . The method according to  claim 13 , wherein the emulated motor reduction noise is adjusted by a speaker transfer function.  
     
     
         16 . The method according to  claim 1 , wherein the muffler active noise reduction unit is adapted to produce the muffler reduction noise by: 
 determining an emulated muffler noise at an error point; and    adjusting the muffler reduction noise to yield emulated muffler reduction noise so as to reduce the emulated muffler noise.    
     
     
         17 . The method according to  claim 16 , wherein the emulated muffler noise is determined by a microphone transfer function.  
     
     
         18 . The method according to  claim 16 , wherein the emulated muffler reduction noise is adjusted by a speaker transfer function.  
     
     
         19 . A cooking hood having a body containing a motor and further containing a muffler mounted on an upper section of the body so as to be in fluid connection therewith, the cooking hood comprising: 
 a motor active noise reduction unit mounted in association with the motor; and    a muffler active noise reduction unit mounted in association with the muffler.    
     
     
         20 . The cooking hood according to  claim 19 , wherein the motor is mounted on a substantially hollow base and the motor active noise reduction unit is mounted in the base.  
     
     
         21 . The cooking hood according to  claim 19 , wherein the muffler includes a hollow space and the muffler active noise reduction unit is distributed in the hollow space.  
     
     
         22 . A motor unit for a cooking hood, said motor unit containing a motor and a motor active noise reduction unit integral therewith.  
     
     
         23 . The motor unit according to  claim 22 , wherein the motor active noise reduction unit comprises: 
 at least one microphone for receiving motor noise;    a speaker capable of producing a motor reduction noise for reducing the motor noise; and    an electronic circuit connecting the speaker and the at least one microphone, for adjusting the motor reduction noise in accordance with the motor noise.    
     
     
         24 . The motor unit according to  claim 23 , wherein the motor active noise reduction unit further comprises: 
 an emulation circuit having respective inputs connected to the speaker and to each microphone and having an output connected to the electronic circuit, for reducing noise at a predetermined error point.    
     
     
         25 . A muffler unit for a cooking hood, said muffler unit containing a muffler and a muffler active noise reduction unit integral therewith.  
     
     
         26 . The muffler unit according to  claim 25 , wherein the muffler active noise reduction unit comprises: 
 at least one microphone for receiving muffler noise;    at least one speaker capable of producing a muffler reduction noise for reducing the muffler noise; and    an electronic circuit connecting the at least one speaker and the at least one microphone, for adjusting the muffler reduction noise in accordance with the muffler noise.    
     
     
         27 . The muffler unit according to  claim 26 , wherein the muffler active noise reduction unit further comprises: 
 an emulation circuit having respective inputs connected to the at least one speaker and to the at least one microphone and having an output connected to the electronic circuit, for reducing noise at a predetermined error point.    
     
     
         28 . The muffler unit according to  claim 26 , wherein the at least one speaker is mounted on an internal surface of a muffler's wall.  
     
     
         29 . The muffler unit according to  claim 26 , wherein one of the at least one speaker is centrally disposed inside the muffler.  
     
     
         30 . The muffler unit according to  claim 27 , wherein the at least one speaker is mounted on an internal surface of a wall of the muffler.  
     
     
         31 . The muffler unit according to  claim 27 , having a single speaker disposed centrally inside the muffler.  
     
     
         32 . A motor active noise reduction unit for reducing motor noise for use in a cooking hood, said motor active noise reduction unit comprising: 
 at least one microphone for receiving the motor noise;    a speaker capable of producing motor reduction noise for reducing the motor noise; and    an electronic circuit connecting the speaker and the at least one microphone, for adjusting the motor reduction noise in accordance with the motor noise.    
     
     
         33 . The motor active noise reduction unit according to  claim 32 , wherein the motor active noise reduction unit further comprises: 
 an emulation circuit having respective inputs connected to the speaker and to the at least one microphone and having an output connected to the electronic circuit, for reducing noise at a predetermined error point.    
     
     
         34 . A muffler active noise reduction unit for reducing muffler noise for use in a cooking hood, said muffler active noise reduction unit comprising: 
 at least one microphone for receiving the muffler noise;    at least one speaker capable of producing muffler reduction noise for reducing the muffler noise; and    an electronic circuit connecting the at least one speaker and the at least one microphone, for adjusting the muffler reduction noise in accordance with the muffler noise.    
     
     
         35 . The muffler active noise reduction unit according to  claim 34 , wherein the muffler active noise reduction unit further comprises: 
 an emulation circuit having respective inputs connected to the at least one speaker and to the at least one microphone and having an output connected to the electronic circuit, for reducing noise at a predetermined error point.