Surface cleaning appliance

A drive system for a surface cleaning appliance having a pair of rotatable head structures employs a worm gear positioned between the head structure in engagement with two spur gears on, respectively, the two head structures.

TECHNICAL FIELD 
This invention is concerned with improving the drive train for a surface 
cleaning appliance having a pair of rotatable head structures for spraying 
and vacuuming the surface. 
BACKGROUND ART 
My U.S. Pat. No. 5,463,791 granted Nov. 7, 1995 for "Surface Cleaning 
Appliance" discloses the type of apparatus to which this invention is 
applicable. 
The drive train from the motor to the rotating heads for the appliance of 
the '791 patent is fairly complex and costly to produce. It includes a 
gear box for speed reduction, a belt drive for one of the rotating heads 
and a spur gear arrangement between the two heads for rotating the 
non-belt-driven head. 
DISCLOSURE OF THE INVENTION 
This invention envisions driving both heads by a worm gear positioned 
between the rotating heads and meshing with a spur gear on each head. The 
worm gear drive further serves as a speed reduction device thus 
eliminating the need for a separate reduction gear.

BEST MODE FOR CARRYING OUT THE INVENTION 
The surface cleaning appliance illustrated in FIG. 1 is designated 
generally by reference numeral 11. The appliance comprises a housing 12 
mounted on wheels 13 for movement across the surface to be cleaned, such 
as a rug. The appliance is manipulated by a handle 14 attached to the 
housing. 
Cleaning fluid under pressure is supplied to the housing 12 by a hose 
system 16 and spent fluid and debris are removed from the housing via 
vacuum hoses 17 connected to hollow handle 14. Hoses 16 and 17 are 
connected, respectively, to sources of cleaning fluid under pressure and a 
vacuum, neither of which are shown. Such sources may, for example, be like 
the system shown and described in U.S. Pat. No. 4,991,254 granted to James 
R. and Michael J. Roden on Feb. 12, 1991 for "Cleaning System". 
The physical act of cleaning a surface is accomplished by a pair of 
rotating cleaning heads 18 which are mounted in housing 12 for rotation in 
side-by-side relationship about vertical axes. Each cleaning head 18 
comprises, in turn, a plurality of vacuum nozzles 19 and a plurality of 
spray nozzles 21 interspersed between the vacuum nozzles. The apparatus 
for conveying cleaning fluid from hose system 16 to spray nozzles 21 and 
for withdrawing spent fluids and debris from vacuum nozzles 19 to vacuum 
hoses 17 are not shown in detail for they are not critical to this 
invention. Such apparatus is shown and described in detail in my 
aforementioned '791 patent which is incorporated herein by reference. 
The present invention is primarily concerned with the drive train by which 
rotation of the shaft 22 of a motor 23 causes rotation of the cleaning 
heads 18. A key component of this drive train is a worm gear 24 secured to 
motor shaft 22. Worm gear 24 is positioned horizontally and equidistant 
between the axes of rotation of cleaning heads 18 for engaging spur gears 
26 mounted on those heads. As indicated by the arrows in FIG. 2 rotation 
of worm gear 24 results in rotation of spur gears 26 and their respective 
cleaning heads 18 in opposite directions. 
The worm gear 24/spur gears 26 drive constitutes a speed reduction device 
and this is a necessary feature for this type of apparatus in which the 
cleaning heads 18 are required to rotate at a speed considerably less than 
the normal rotating speed of the motor shaft 22. Thus, no separate speed 
reduction unit need be provided as was the case in the apparatus disclosed 
in my '791 patent. 
It should further be noted that the worm gear 24/spur gears 26 drive causes 
rotation of the cleaning heads 18 to be synchronized at all times. This 
means that with the vacuum nozzles 19 in one cleaning head 18 angularly 
offset from the vacuum nozzles of the other head 18 there is no 
interference between the two sets of vacuum nozzles even though their 
paths overlap slightly between the heads. The overlap, of course, is 
desirable to eliminate a strip of untreated surface between the heads 18. 
From the foregoing it should be appreciated that this invention provides an 
improved drive arrangement for dual headed surface cleaning appliances.