The field of the invention relates to suction cleaners often called vacuum cleaners and more particularly to those with agitators. The field also includes both rotating types, revolving and reciprocating, as are designed for cleaning floors and other surfaces whether smooth or of indefinite surface depth.
All known prior art with rotatable agitators employ nozzles with large area mouths. As in typical nozzle mouths, this invention has a rectangular nozzle mouth and contains a rotating agitator roll equipped with at least one brush strip. U.S. Pat. Nos. 2,734,211 and 2,734,212 are typical of the prior art.
In the prior art the length of the brush bristle tufts determine the distance the agitator roll is located above the plane of the mouth margins and also determines the size of the airstream flow patterns about both sides of the agitator roll, as it is ducted between the agitator roll and the mouth margins. These cross-sections of the airstream between the agitator roll and the nozzle margins are usually 10 square inches compared to the usual 1.5 square inches cross-section of the downstream air passageway through which the same air must pass enroute to the dust bag. This passageway constriction results in a very slow air flow speed across the nozzle mouth and across the surface to be cleaned. Along with the slow speed is a low differential air pressure drop across the surface to be cleaned resulting in known inefficient cleaning effectiveness.
These low air speeds at the nozzle mouth results in uneven speeds across the portions of the nozzle mouth farthest from the mouth of the much smaller passageway immediately downstream of the nozzle mouth. These different flow speeds in different portions of the nozzle mouth result in areas of the surface being cleaned being less clean than adjacent areas. None of the art has shortened standard tuft lengths so as to operate agitators closer to the nozzle mouths, a length certain to abrade surfaces and decrease brush efficiency while causing the brush to rapidly wear out.
It is also known that much of the prior art has attempted to compensate for this cleaning deficiency by increasing the motor size for more airstream flow speed and more agitator roll revolving speed, and by decreasing the size of the internal geometry of the passageway mouth behind the agitator roll; the first resulting in a very heavy cleaner and the second in easy clogging of the mouth of the passageway. The weight has further resulted in powered traction assistance for moving the heavy cleaner over floor surfaces to be cleaned. The big motors and fast agitator roll speeds have also resulted in unnecessary wear of carpeting and the still too low air pressure differential fails to lift the heavier particles and certain other materials from shag-type carpeting that a higher pressure differential would better clean.
None of the known prior art has produced, invented, suggested or recognized the need of structure for restricting and changing the dimensions of the cross-sectional areas of the airstreams between both agitator roll sides and the nozzle mouth margins as a method for increasing efficiency, or of structure for providing at least one cavity in the agitator roll for recessing the major portion of at least one brush strip in the agitator roll so that the roll could be rotated in closer proximity to the margins of the nozzle mouth without modifying standard brush designs as does this invention.