Dual filter vacuum cleaner apparatus

Abstract

A dual filter arrangement for a vacuum cleaner for filtering particles of dust and debris from an airflow passing through the vacuum cleaner. The dual filter comprises a coarse pre-filter having an array of pores formed therein of substantially uniform diameter and a fine primary filter which is located rearwardly of the pre-filter in the direction of flow of the airflow. The dual filter is releasably latched to a main housing portion of the vacuum cleaner housing. A nose cone is removably secured to the housing and circumscribes the dual filter assembly. The dual filter enables even more efficient filtering of contaminants from dust and dirt entrained air ingested by the vacuum cleaner. Attachment of the dual filter to the main housing portion provides the additional advantage of increasing the capacity of the nose cone and eliminating the need for the user to handle the dual filter assembly when emptying contaminants collected within the nose cone. A unique seal arrangement provides a substantially airtight seal between the dual filter system and the main housing to which it is secured.

1. A hand held vacuum cleaner having a vacuum source and a dual filter system for filtering particles of dust and debris from an airflow passing  drawn through the vacuum cleaner by the vacuum source, comprising:
 a coarse pre-filter forming an open ended substantially box shape defining side surfaces and an end surface and having pores formed on all of said side and end surfaces;  
 a fine primary filter which is located downstream of the pre-filter in the direction of flow of the airflow; and  
 wherein the pre-filter has a recess for receipt of  the primary filter is configured to be nestably received within the open end of the pre-filter so that the primary filter filters airflow drawn through all of the side and end surfaces of the pre-filter.  
 
     
     
       2. The vacuum cleaner of  claim 1 , wherein the diameter of the pores of the pre-filter is set at a substantially uniform value. 
     
     
       3. The vacuum cleaner of  claim 2 , wherein the diameter of the pores of the pre-filter is set at one substantially uniform value within the range approximately 0.75 mm to 1.75 mm. 
     
     
       4. The vacuum cleaner of  claim 3 , wherein the diameter of the pores of the pre-filter each comprise a substantially uniform value of approximately 1 mm. 
     
     
       5. The vacuum cleaner of  claim 1 , wherein the primary filter comprises a concertina shaped arrangement of a filter material. 
     
     
       6. The vacuum cleaner of  claim 5 , wherein the primary filter comprises a frame and the concertina shaped arrangement of a fine filter material and the concertina shape of the filter material is supported in and maintained by the frame. 
     
     
       7. The vacuum cleaner of  claim 6 , wherein the frame includes two opposing arrays of arms and the concertina shaped arrangement of the filter material is supported between opposing pairs of said arms. 
     
     
       8. The vacuum cleaner of  claim 7 , wherein the frame of the primary filter comprises a molded plastics  material. 
     
     
       9. The vacuum cleaner of  claim 1 , wherein the pre-filter is made from a molded plastic material. 
     
     
       10. The vacuum cleaner of  claim 1 , wherein the pre-filter has a peripheral rim via  which is fitted to the primary filter and to a housing part of a vacuum cleaner, wherein a peripheral seal element made of a resilient material surrounds said rim. 
     
     
       11. A hand held vacuum cleaner system comprising:
 a housing;  
 an electric motor disposed within said housing;  
 a fan driven by said electric motor for generating a suction airflow of air-entrained dirt and debris;  
 a dual filter system including: 
 a pre-filter for filtering coarse particles of dirt and debris from the dirt and debris entrained air;  
 a primary filter for filtering fine particles of dirt and debris from the entrained air;  
 said pre-filter forming an open ended substantially box shape defining side surfaces and an end surface and having pores formed on all of said side and end surfaces and said primary filter being adapted to rest nestably within said pre-filter for filtering airflow drawn through all of the side and end surfaces of the pre- filter;    
 said primary filter further comprising a concertina shaped filtering material; and  
 
 said housing and at least one of said pre-filter and primary filter including cooperating latching structure for mechanically interengaging to releasably secure said pre-filter and said primary filter to said housing.  
 
     
     
       12. The vacuum cleaner of  claim 11 , wherein said pre-filter further comprises a resilient seal secured to a peripheral flange of said pre-filter. 
     
     
       13. The vacuum cleaner of  claim 12 , wherein said resilient seal operates to form a relatively airtight seal between said pre-filter and said housing when said dual filter system is secure to said housing. 
     
     
       14. The vacuum cleaner of  claim 11 , wherein said primary filter includes a frame having said concertina shaped filtering material integrally formed therewith such that said concertina shaped filtering material is supported by said frame and is not removable from said frame. 
     
     
       15. A hand held vacuum cleaner for filtering particles of dust and debris from an airflow passing through the vacuum cleaner, comprising:
 a primary filter;    a pre-filter nestably housed adjacent to the primary filter; and    wherein, the primary filter is located downstream of the pre-filter in the direction of flow of the airflow.    
     
     
       16. A hand held vacuum cleaner for filtering particles of dust and debris from an airflow passing through the vacuum cleaner, comprising:
 a cup-shaped pre-filter; and    a concertina-shaped primary filter disposed adjacent to the pre-filter.    
     
     
       17. A hand held vacuum cleaner for filtering particles of dust and debris from an airflow passing through the vacuum cleaner, comprising:
   a substantially cup - shaped pre - filter defining side surfaces and a bottom surface and having pores formed in all surfaces thereof; and        a second filter nestably disposed adjacent to the pre - filter and downstream of the pre - filter in the direction of airflow so that the second filter filters airflow drawn through all surfaces of the pre-filter;        wherein all of said airflow is filtered by said pre-filter.     
     
     
       18. For use in a hand held vacuum cleaner having plural filters for filtering particles of dust and debris from an airflow passing through the vacuum cleaner, the improvement comprising a fine filter including:
   a frame having a planar surface with openings formed therein operable to locate the fine filter in the vacuum cleaner, and        a fine filter element mounted on said frame and extending upwardly from said planar surface and adapted to be received within a recess in a coarse pre - filter so as to be located rearwardly of the pre - filter in the direction of flow of the airflow when said fine filter is installed in the vacuum cleaner.     
     
     
       19. The apparatus of  claim 18  wherein the frame comprises a planar rim and side support frames for supporting said fine filter element. 
     
     
       20. The apparatus of  claim 19  wherein said openings comprise keyhole- shaped apertures for engaging pegs on a housing surface of the vacuum cleaner for securing the fine filter to the housing.   
     
     
       21. The apparatus of  claim 18  wherein said frame is configured to be non- rotatably fixed within the recess in the pre - filter.   
     
     
       22. A method of filtering particulates from an airflow drawn through a hand held vacuum cleaner by a vacuum source, comprising the steps of:
   providing a fine filter having a rim, two side support frames, and filter material located between the two side support frames;        placing the fine filter downstream of a pre - filter within a recess in the pre - filter so that the particulates collected on the fine filter are less likely to conglomerate; and        jointly securing the fine filter and pre - filter to a housing surface of the hand held vacuum cleaner;        wherein said rim of said fine filter is provided with apertures for engaging pegs on the housing source to secure the fine filter thereto.     
     
     
       23. The vacuum cleaner of  claim 10  wherein the peripheral rim is provided with apertures for engaging pegs on the housing part of the vacuum cleanser to secure the pre- filter and the primary filter thereto.   
     
     
       24. The vacuum cleaner of  claim 12  wherein the peripheral flange of said pre- filter is provided with apertures for engaging pegs on said housing for releasably securing said pre - filter and said primary filter to the housing.   
     
     
       25. The vacuum cleaner of  claim 1  wherein all of said airflow is filtered by said pre- filter.   
     
     
       26. The vacuum cleaner of  claim 11  wherein all of said airflow is filtered by said pre- filter.