Vacuum cleaner and a filter assembly therefor

The invention provides a vacuum cleaner (100) including an airflow path, dirt and dust collecting device arranged in the airflow path, a motor or fan unit (110) for causing air to flow along the airflow path and also arranged therein, a first filter (112) arranged immediately upstream of the motor or fan unit (110) and a second filter (114) arranged downstream of the motor or fan unit (110), wherein the arrangement is such that, when in use the dirt and dust collecting device are made accessible or removed for emptying or replacement, both filters (112, 114) are visible to the user. This arrangement encourages the user of the vacuum cleaner to regularly maintain both filters (112, 114), thus improving the performance of the vacuum cleaner (100).

BACKGROUND OF THE INVENTION 
(1) Summary of the Invention 
The invention relates to a vacuum cleaner and to a filter assembly 
therefor. It will be understood that the term "vacuum cleaner" is here 
used so as to encompass any type of cleaning apparatus which uses the 
creation of a vacuum to draw air along an airflow path. 
(2) Description of Related Art 
Vacuum cleaners of both the upright and cylinder types operate by utilising 
a motor or fan unit to draw air along an airflow path from a dirty air 
inlet to a clean air outlet via some sort of filtering or dirt/dust 
separating apparatus. The air which passes along the airflow path thus 
passes through the motor or fan unit. 
It is known to filter the air passing along the airflow path before it is 
expelled to the atmosphere. If the appropriate filter is located upstream 
of the motor or fan unit, any particles of dirt, carbon, etc becoming 
entrained within the airflow inside the motor or fan unit will inevitably 
be expelled into the atmosphere with the airflow. If the filter is located 
downstream of the motor or fan unit, any dirt or dust remaining in the 
airflow after it has passed through the filtering or dirt/dust separating 
apparatus will pass through the motor or fan unit. This may cause the 
motor or fan unit to become unbalanced which will shorten its life and may 
result in premature failure. Also, dust can collect and build up in the 
region of the motor or fan unit which can result in sudden unwanted 
releases of large quantities of fine dust which can cause blockage of the 
filter or damage the motor or fan unit. 
A very few manufacturers have, prior to the date of this application, been 
fitting electrostatic filters both before and after the motor or fan unit. 
This has the advantage of preventing dusty air from passing through the 
motor or fan unit and also of preventing any particles released within the 
motor or fan unit from escaping into the atmosphere. However, two problems 
have been identified in respect of this arrangement. Firstly, even if the 
operator remembers to change one of the filters, the second filter is 
rarely changed. Presumably this is because changing the first filter gives 
the operator sufficiently improved performance for the changing of the 
second filter to be thought unnecessary or else the second filter is 
forgotten. Secondly, the operator has difficulty in ascertaining that the 
filters require changing because they are not easily visible. 
It is an object of the present invention to provide a filter assembly for 
use in such a vacuum cleaner.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The present invention relates to a vacuum cleaner comprising an airflow 
path, dirt and dust collecting means arranged in the airflow path, a motor 
or fan unit for causing air to flow along the airflow path and also 
arranged therein, a first filter arranged immediately upstream of the 
motor or fan unit and a second filter arranged downstream of the motor or 
fan unit, wherein the arrangement is such that, when in use the dirt and 
dust collecting means are made accessible or removed for emptying or 
replacement, both filters are visible to the user. 
An embodiment of the invention will now be described with reference to the 
accompanying drawing wherein: 
The sole drawing FIGURE shows a vacuum cleaner arranged in accordance with 
the invention. 
The sole drawing FIGURE illustrates the present invention. This drawing 
shows a vacuum cleaner 100 having a cover 102 which is hinged to a casing 
104 about an axis 106 so as to be movable between a closed position 
(illustrated in solid lines) and an open position (illustrated in broken 
lines). Inside the casing 104 are located dirt or dust collecting means 
(not shown) and a motor or fan unit 110. First and second filters 112,114 
are located immediately upstream and downstream respectively of the motor 
or fan unit 110. The filters 112,114 are preferably electrostatic filters 
but alternative types of filter are equally suitable. Furthermore, the 
filters 112,114 can be connected together to form a single filter assembly 
if desired. 
The motor or fan unit 110 is located inside the casing 104 such that, when 
the cover 102 is moved from the closed position to the open position, the 
filters 112,114 become visible to the user of the machine. This allows the 
user to see quickly and easily whether either of the filters 112,114 
requires to be replaced or cleaned. This in turn encourages the user to 
replace each filter 112,114 as and when required which improves the 
performance of the vacuum cleaner 100. 
The movement of the cover 102 from the closed position to the open position 
is necessary in order to provide access to the dirt and dust collecting 
means for emptying or replacement purposes. Thus, if a bag or bin is 
located inside the casing 104, the user is encouraged to look at the 
filters 112,114 each time the bag or bin is emptied of dirt or dust 
collected by the vacuum cleaner 100. The vacuum cleaner 100 shown in FIG. 
1 is a cylinder-type vacuum cleaner which preferably incorporates cyclonic 
dirt or dust collecting means (not shown) located inside the casing 104. 
However, it is possible to apply the present invention to upright-type 
vacuum cleaners. The filters, which are unsightly, can be concealed from 
view when the vacuum cleaner is in normal use by a cover or panel, or else 
by the dirt or dust separating means themselves. When the cover or panel 
is removed, or the dirt or dust collecting means is removed for emptying 
or replacement, both filters are rendered visible to the user. 
It will be appreciated by a reader skilled in the art that the invention is 
not restricted to the specific embodiment described above.