air inlet opening and an air outlet opening which communicates with the outside of the canister. In the use of such vacuum cleaners, actuation of the motor causes a rapid flow of air from the interior of the cavity or housing into the motor air inlet opening, such air being expelled to the exterior or outside of the vacuum cleaner housing. A continuous supply of air is provided which enters through a housing inlet opening. This air, which carries dust, small particles and other debric, is caused to enter a vacuum cleaner bag, which expands from its generally collapsed condition when the vacuum cleaner motor is inoperative. Being made of a porous sheet of material which permits the penetration of air therethrough, the air which enters the vacuumcleaner bag passes through the wall material and into the cavity, from which it is drawn into the motor. Clearly, the vacuum cleaner bag material acts as a filter which retains the debris while permitting the air to pass therethrough to be expelled outside of the unit.
The tendency of the air flow is to take the most direct and shortest route between the housing inlet opening and the motor inlet opening. When the vacuum cleaner bag extends further or beyond the motor inlet opening, it frequently occurs that the debris primarily accumulates in the region between the housing and motor inlet openings and the more remote parts of the bag remain substantially unfilled.