Vacuum cleaner

A vacuum cleaner including a dust chamber, a vacuum chamber and a source for producing low pressure in the vacuum chamber, wherein the dust chamber and the vacuum chamber are partitioned by a first filter unit, and wherein the vacuum chamber is provided with a secondary filter unit in which at least one filter element is suspended from the ceiling of the vacuum chamber radially thereof. A rotary shaft is provided at the center of the radially arranged filter elements, the rotary shaft radially supporting vibrating vanes, each of which is designed to vibrate each filter element of the secondary filter unit on its inner peripheral portion, thereby causing the dust entrained therein to fall off by vibration. The rotary shaft is additionally provided with a single vibrating arm horizontally extended so as to vibrate each filter element of the secondary filter unit on its bottom portion.

BACKGROUND OF THE INVENTION 
The present invention relates to a vacuum cleaner having a dual filter 
structure whereby the collected dust and dirt is dually filtered out, 
thereby protecting the motor against choking due to dust. More 
particularly, the present invention relates to a vacuum cleaner having a 
dual filter structure of which one filter unit is subjected to timely 
vibration, thereby protecting the same against choking due to dust 
entrained thereon. 
The vacuum cleaner is known, and widely used for house, factory and office 
cleaning. The vacuum cleaner is provided with a filter whereby the 
collected dust and dirt is filtered out. The conventional filter is 
provided in the form of a bag, commonly called a filter bag. However, it 
is difficult to filter out the dust and dirt with such a filter bag, and 
unfiltered impurities pass through the filter meshes, and enter into the 
cage of the motor, where they stick to every oily surface of the motor 
components. Eventually, the build-up of the impurities causes choking of 
the motor, and at least reduces its efficiency. Choking often leads to 
seizure, and shortens the life of the motor. In addition, the filter 
elements are also liable to become blocked. 
OBJECTS AND SUMMARY OF THE INVENTION 
The present invention is directed toward solving the problems pointed out 
above, and has for its object to provide a vaccum cleaner having a dual 
filter structure which is provided with a dust removing means, whereby the 
motor is protected against choking over a long period of use. 
Other objects and advantages of the present invention will become apparent 
from the detailed description given hereinafter; it should be understood, 
however, that the detailed description and specific embodiment are given 
by way of illustration only, since various changes and modifications 
within the spirit and scope of the invention will become apparent to those 
skilled in the art from this detailed description. 
According to the present invention, there is provided a vacuum cleaner 
which comprises: 
a dust chamber for collecting dust, dirt and moisture; 
a vacuum chamber located above the dust chamber, the vacuum chamber 
including an air inlet through which the outside air is drawn therein 
under low pressure; 
means for creating low pressure in the vacuum chamber; 
a plurality of first filter elements located between the dust chamber and 
the vacuum chamber; 
a plurality of secondary filter elements suspended from the ceiling of the 
vacuum chamber, wherein the secondary filter elements are radially 
arranged around a rotary shaft supported axially of the vacuum chamber; 
a vibrating means for causing the dust and dirt entrained in the secondary 
filter elements to fall off by vibration, wherein the vibrating means 
comprises a plurality of vanes fixed to the rotary shaft, and a single 
vibrating arm horizontally extended therefrom; and 
a driving means for rotating the rotary shaft alternately in a clockwise 
and counter-clockwise direction.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, dust is collected in a dust chamber 1, above which a 
vacuum chamber 2 is removably provided. The vacuum chamber 2 has an air 
inlet 3. There is provided an electric motor 4 located in a motor chamber 
5, which is airtightly fixed to the vacuum chamber 2 with the use of an 
air seal 6, such as an O-ring. The reference numerals 7, 7' designate a 
pair of filter supports of lattice structure, each of which is made up of 
a plurality of concentrically arranged rings and radially arranged spokes 
supporting the rings. The upper filter support 7 has a bearing section 8 
at its center, and the lower filter support 7' has an aperture 9. The 
reference numeral 10 designates an air duct communicating with the air 
inlet 3, the air duct 10 being passed through a peripheral portion of the 
filter supports 7, 7', so as to allow air drawn in to pass through the 
filter unit 11. The filter unit 11 is fixed by a bolt 12 between the 
filter supports 7 and 7'. In this way the dust chamber 1 and the vacuum 
chamber 2 are partitioned by the filter unit 11. 
The bearing section 8 of the upper filter support 7 rotatively supports a 
hollow shaft 16, which radially supports a plurality of vibrating vanes 
15. The vibrating vanes 15 are designed to remove the dust entrained in 
secondary filter elements 14 suspended from the ceiling 13 of the vacuum 
chamber 2, wherein the vibrating vanes 15 vibrate each of the secondary 
filter elements 14 on its peripheral portion while they are in rotation. 
The ceiling 13 has a number of recesses (not shown) corresponding to that 
of the second filter elements 14, and each of the filter elements 14 is 
fixedly inserted therein. In addition, one of the vibrating vanes 15 is 
provided with vibrating arm 17 horizontally extending therefrom, whereby 
each bottom portion of the suspended filter elements 14 is vibrated so as 
to allow the dust entrained on the filters 14 to fall off. The vibrating 
vanes 15 are rotated in the following way: 
One of the vibrating vanes 15 is provided with a small pipe 18 through 
which a string 19 is passed. Each end of the string is passed through an 
opening in the vacuum chamber and a grip ball 20 is provided at each end. 
The operator holds the grip balls with both hands and pulls each end of 
string 19 alternately thereby causing the hollow shaft 16 to rotate on the 
bearing section 8 alternately in a clockwise and counterclockwise 
direction. The string 19 is of such length that the grip balls may be 
stored in the air inlet 3 when no in use. 
The reference numeral 21 designates a float usable for indicating a liquid 
level if water, waste oil or any other liquid is introduced into the dust 
chamber 1. The detailed description of its structure and function will be 
omitted for simplicity. 
As evident from the foregoing description, the vacuum cleaner of the 
invention is provided with a first filter unit and a secondary filter 
unit, of which the filter elements of the secondary unit are subjected to 
vibration caused by the vibrating vanes 15 and the vibrating arm 17, 
thereby allowing the dust and dirt entrained thereon to fall off. Thus the 
filter elements 14 are kept free from an undesirable buid-up of dust. This 
ensures a constant filtering efficiency of the second filter unit. 
According to the present invention, the vacuum cleaner has two filter 
units, that is, the first filter unit and the secondary filter unit, 
wherein the first filter unit is made in relatively large meshes whereas 
the secondary filter unit is made in relatively small meshes. Owing to the 
dual filter system, the collected dust and dirt is filtered out twice, 
thereby ensuring that the impurities are prevented from entering the motor 
cage.