Cleaning Nozzle Design Considerations
When it comes to cleaning performance, there is a tendency to look
primarily at the power of the suction motor and
the amount of bristles on the brush roll.
While these are important considerations, the design of the cleaning
nozzle can have a significant effect as well. It is the force exerted by
the air flow combined with agitation, that actually picks up the dirt at
the cleaning nozzle. This article explores some nozzle designs which will
improve the actual cleaning performance of many vacuum cleaners.
 |
Nozzle Designs Affecting the Air Flow Velocity |
 |
 |
|
The velocity of the air flow in the nozzle is affected by the nozzle
design as well as the amount of air flowing through the entire vacuum
cleaner system. Our article on Air Flow Through the
System discusses additional factors which affect the air flow and how
they relate to actual cleaning performance.
The higher the velocity of the air flow close to the surface being
cleaned, the better the cleaning performance will be. The smaller the area
through which the air flow is passing, the greater will be velocity will
be. For this reason most nozzles, especially carpet nozzles without
revolving brush rolls, have fairly narrow openings across their full width.
To clean below the carpet's surface they must cause the air to flow
through the carpet fibers with sufficient velocity to force the dirt to
move with it. To remove dirt and grit embedded deep within a carpet is
virtually impossible using air flow alone so uprights and power nozzles
with revolving brush rolls were developed.
Their effect is discussed further in our article on the
Effects of Brushing Action.
Many floor brush attachments are designed with a row of bristles around
their perimeter with the bristles along the front being shorter to allow a
space for the dirt to enter. Another floor brush design has a single brush
strip which is centered front to back plus some short rows of bristles on
the front and rear edge near the center to keep it fairly level. Both
designs work well as long as they keep the air flow as close to the floor
surface as possible. This typically is done on floor brushes with the
perimeter bristles by having a short wall along the inside edge of the
bristles so the gap between it and the floor is sufficiently small. This
wall also prevents bristles from being pulled inward by the air flow
moving through them. The bristle lengths of the center mounted strip are
relatively short so the gap between the floor and attachment body is also
sufficiently small.
The air flow velocity should be similar across the full width of the
nozzle so all areas are cleaned well. Most cleaning attachments have
funnel shaped air passages which lead to centered hose or wand connectors.
This allows the air to uniformly flow from all locations across the
nozzle. As discussed below, some uprights and power nozzles have similar
designs as well. Unfortunately, many uprights with on-board attachments
have brush roll housings with the air inlets very close to one of their
sides so the air flow velocity is significantly greater on that side
compared to the opposite side. Also, many roll housing rear walls on these
uprights are straight rather than funnel shaped, increasing that undesired
effect even more. All power nozzles have air inlets near the center of the
nozzle but those with straight rear walls will experience less air flow
velocity closer to the nozzle edges although not to the degree which
uprights with non-centered inlets experience.
|
High Performing Upright & Power Nozzle Designs |
|
|
|
As mentioned above, the nozzle should also be designed so it produces
similar air flow velocity across its
complete width, not just near the air passage leading from it. Some
uprights and power nozzles incorporate a center mounted air intake behind
or above the brush roll which flares out to the edges of the cleaning
nozzle as it approaches the brush roll. This wide funnel shaped opening
causes the air flow to be distributed quite evenly across the entire
cleaning width for more efficient and uniform cleaning. This also creates
a dirt collection area immediately behind or above the brush roll so most
of the dirt and grit is gathered by the brushes and whisk away by the air
flow before it can bounce back out of the nozzle. This substantially
reduces the scatter effect which many uprights and power nozzles
experience when picking up grit and small stones.
Examples of uprights which use this design are the
Lindhaus upright, Commercial
Eureka uprights, Commercial and Heavy Duty
Sanitaire uprights by
Electrolux Home Care Products North America
(formerly The Eureka Company)
and Kirby uprights. All of these are high
performing uprights, most of which are traditional
uprights which combine this design with large diameter
fans for outstanding carpet cleaning
performance. Examples of power nozzles which use a similar design are those
made by Lindhaus and
Panasonic.
|
New WindTunnel Nozzle Design |
|
|
|
In 1997 The Hoover Company introduced their
new WindTunnel Upright series which
incorporates an innovative brush roll housing design. The traditional way
of making a brush roll housing is to make a long box shaped area which is
open on the bottom and has an air passage leading from its back or top. As
mentioned above, some air passages are funnel shaped and form a
collection area for improved cleaning.
The best way to visualize the WindTunnel nozzle design is to think of a
roll housing within a larger roll housing. This creates an air passage
around the front, top and rear of the inner housing. The inner housing's
front and rear walls don't extend completely down to the nozzle's base,
creating a 3/8" high opening along the front and rear of the inner
housing. The air inlet leads from the outer housing as well as a matching
hole in the inner housing. This design allows air to flow directly from
the inner housing's brush roll area through the hole as well as through the
3/8" high front and rear openings, through the air passage around the
inner housing and into the air inlet leading to the hose and paper bag.
Carpet cleaning is affected by the WindTunnel design in two important
areas. By having the outer air passage, the air flow is distributed more
evenly over the entire cleaning width even though the air inlet is not
completely centered nor funnel shaped as mentioned above. The other aspect
is the reduction of the scatter effect when picking up dirt and grit since
they are brushed into the 3/8" opening along the back of the inner housing
and whisk away by the air flow. In a nutshell, Hoover has created the same
basic cleaning effect as the center mounted, funnel shaped nozzle inlets
mentioned above but with a nozzle design which is more conducive to most
clean-air upright designs.
This new WindTunnel series marks the return of The Hoover Company to
using the "clean-air" design for their
better uprights. They were the innovators of the clean-air upright design
many years ago when they introduced their Dial-a-Matic series. While other
companies like Panasonic,
Simplicity
and Riccar copied the Dial-a-matic upright's
basic design, after manufacturing it for many years, Hoover returned to
using only the traditional upright
design in all of their uprights. Only time will tell how many other
companies will create similar nozzle designs for their "clean-air" uprights.
Since Hoover has patented this innovative design, competing companies will
need to modify its design sufficently to not infringe on Hoover's rights.
Most vacuum cleaners include a small nozzle about 4" to 6" wide with a
fairly narrow opening about 1/4" to 3/4" deep. This nozzle, often called
the upholstery tool, is designed for cleaning upholstered furniture,
window curtains and carpeted stairs. The air inlet is designed in a funnel
shape so air flow if distributed quite evenly across the entire cleaning
width. Since the air flow is restricted to a much smaller area than the
larger carpet nozzle, when all else fails due to poor vacuum cleaner
performance, it is used by some for cleaning carpet as well.
To loosen dirt and help pick up pet hair and threads, many upholstery
nozzles have a straight brush strip mounted just behind the opening. Some
companies have developed motor or turbine driven revolving or rotating
brushes which provide agitation for more
effective cleaning. Examples of upholstery nozzles with motor driven
revolving brush rolls are those included
with some deluxe Kenmore,
Panasonic and
Aerus (formerly Electrolux)
power teams. The motors in these nozzles actually adds power to the system
whereas those driven by turbines draw their power from the air flow. Turbine
driven upholstery nozzles with rotating brushes are included with many
Hoover uprights and SteamVacs as well as
the Kirby uprights. Available for use on most
vacuum cleaners are upholstery nozzles with turbine driven revolving brush
rolls like the Miele STB 101 Turbobrush
and
generic 0905C and 120 Air Turbine Upholstery Nozzles.
Whether motor driven or turbine driven, these powered brushes can make
a significant difference in the effectiveness of their upholstery nozzles.
Sufficient force from the air flow velocity as well as agitation from
revolving or rotating brushes can make a huge difference in the cleaning
performance of a vacuum cleaner, especially on carpet and upholstery. Both
high performing uprights and canisters with power nozzles (power teams)
are available to match your cleaning style and preference. Typically, both
will clean very well although some better than others due to their nozzle
designs as well as other system designs.
A few companies like Electrolux Home Care Products North America
(formerly The Eureka Company)
(Commercial & Sanitaire) and
Kirby still make the traditional upright
designs with the funnel shaped nozzle housings. These are very durable
uprights which have outstanding performance when it comes to cleaning
carpeted floors. If high filtration is needed though, look more to
very durable and high performing "clean-air"
uprights with HEPA filtration and sealed
systems like the new Lindhaus
HEALTHCAREpro HEPA two-motor upright.  |
