Electrostatic atomiser

Abstract

The present invention relates to (with reference to FIG. 1 ) an electrostatic fluid atomiser which has a fluid inlet ( 2 ) and a fluid channel ( 3 ) leading fluid to a wall ( 6 ) in which orifices ( 100 ) are formed. Fluid passing out of the orifices ( 100 ) is atomised into droplets which fall into a first set of larger droplets ( 12 ) and a second set of smaller droplets ( 13 ). Two charging electrodes ( 4,6 ) charge fluid passing through the channel ( 3 ). A droplet separator ( 200 ) has a separator electrode ( 16 ) which applies an electrical force on the droplets and deflects the smaller droplets ( 13 ) to he collected by a droplet collector ( 15 ) while the larger droplets ( 12 ) continue undeflected out of a droplet ( 201 ) of the atomiser.

1 . An electrostatic atomiser, comprising:
 a fluid inlet;   one or more orifices out of which the fluid emerges in an atomised form which comprises at least a first set of droplets of comparable size to each other and a second set of droplets of comparable size to each other and of a smaller size to the droplets of the first set;   a fluid channel connecting the fluid inlet to the orifice(s); and   at least two charging electrodes for applying a charge to fluid passing through the fluid channel; wherein   the electrostatic atomiser comprises a fluid droplet separator extending downstream of the orifices having a first separator electrode which is either earthed or electrically charged and which applies an electrical force on the droplets which deflects the second set of smaller droplets to a droplet collector while allowing the first set of larger droplets to continue out of a droplet outlet of the atomiser; and   the droplet collector is located upstream of the fluid outlet whereby only the larger droplets of the first set are output by the atomiser out of the droplet outlet, the smaller droplets of the first set having been collected within the atomiser by the droplet collector.   
   
   
       2 . An electrostatic atomiser according to  claim 1  wherein said droplet collector comprises an absorbent layer. 
   
   
       3 . An electrostatic atomiser as claimed in  claim 1  wherein the first separator electrode applies an attractive electrical force on the fluid droplets attracting the fluid droplets to move towards the first separator electrode. 
   
   
       4 . An electrostatic atomiser as claimed in  claim 1  wherein the first separator electrode is a cylindrical wall disposed around the orifices and extending downstream. 
   
   
       5 . An electrostatic atomiser as claimed in  claim 4  comprising a second separator electrode extending spaced apart from and parallel to the cylindrical wall and either earthed or charged to apply an attractive electrical force on the droplets, the atomiser having a second fluid droplet collector which collects the droplets attracted by the second separator electrode. 
   
   
       6 . An electrostatic atomiser as claimed in  claim 5  wherein the second fluid droplet collector is connected to a fluid return via a conduit which passes through passages formed in the charging electrodes, the fluid return returning fluid collected by the droplet collector to the fluid inlet. 
   
   
       7 . An electrostatic atomiser as claimed in  claim 1  wherein the orifices are provided in an orifice wall and said fluid droplet separator comprises a plurality of fluid collectors spaced apart from each other and extending from locations on the orifice wall located between the orifices and extending from the orifice wall in a downstream direction. 
   
   
       8 . An electrostatic atomiser as claimed in  claim 7  wherein each of the fluid collectors is associated with a separator electrode individual thereto which is electrically charged to attract the fluid droplets to the fluid collector. 
   
   
       9 . An electrostatic atomiser as claimed in  claim 7  wherein the orifice wall functions as a charging electrode. 
   
   
       10 . An electrostatic atomiser as claimed in  claim 3  comprising a second separator electrode spaced apart from the first separator electrode and electrically charged with a voltage of a different polarity to the first separator electrode, and which applies a repelling electrical force on the fluid droplets repelling the fluid droplets away from the second electrode towards the droplet collector. 
   
   
       11 . An electrostatic atomiser as claimed in  claim 1  wherein the orifices are provided in an orifice wall which also functions as one of the charging electrodes. 
   
   
       12 . An electrostatic atomiser as claimed in  claim 1  further comprising a fluid return for returning fluid collected by the droplet collector to the fluid inlet. 
   
   
       13 . An electrostatic atomiser as claimed in  claim 1  wherein the atomiser incorporates multiple orifices in close proximity to a substantially planar surface of a charging electrode which spans said multiple orifices. 
   
   
       14 . An electrostatic atomiser as claimed in  claim 1  comprising orifices angled to generate converging streams of droplets. 
   
   
       15 . An electrostatic atomiser as claimed in  claim 1  comprising orifices angled to generate diverging streams of droplets. 
   
   
       16 . An electrostatic atomiser as claimed in  claim 1 , wherein the first separator electrode is electrically connected to one of said charging electrodes. 
   
   
       17 . An electrostatic atomiser as claimed in  claim 5  wherein the second separator electrode is electrically connected to one of said charging electrodes. 
   
   
       18 . An electrostatic atomiser as claimed in  claim 2  wherein the first separator electrode applies an attractive electrical force on the fluid droplets attracting the fluid droplets to move towards the first separator electrode. 
   
   
       19 . An electrostatic atomiser as claimed in  claim 3  wherein the first separator electrode is a cylindrical wall disposed around the orifices and extending downstream. 
   
   
       20 . An electrostatic atomiser as claimed in  claim 19  comprising a second separator electrode extending spaced apart from and parallel to the cylindrical wall and either earthed or charged to apply an attractive electrical force on the droplets, the atomiser having a second fluid droplet collector which collects the droplets attracted by the second separator electrode. 
   
   
       21 . An electrostatic atomiser as claimed in  claim 20  wherein the second fluid droplet collector is connected to a fluid return via a conduit which passes through passages formed in the charging electrodes, the fluid return returning fluid collected by the droplet collector to the fluid inlet. 
   
   
       22 . An electrostatic atomiser as claimed in  claim 21  wherein the orifices are provided in an orifice wall and said fluid droplet separator comprises a plurality of fluid collectors spaced apart from each other and extending from locations on the orifice wall located between the orifices and extending from the orifice wall in a downstream direction. 
   
   
       23 . An electrostatic atomiser as claimed in  claim 22  wherein each of the fluid collectors is associated with a separator electrode individual thereto which is electrically charged to attract the fluid droplets to the fluid collector. 
   
   
       24 . An electrostatic atomiser as claimed in  claim 23  wherein the orifice wall functions as a charging electrode. 
   
   
       25 . An electrostatic atomiser as claimed in  claim 3 , wherein the first separator electrode is electrically connected to one of said charging electrodes.