Note: Descriptions are shown in the official language in which they were submitted.
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SWIMMING POOL PRESSURE CLEANER
WITH INTERNAL STEERING MECHANISM
FIELD OF THE INVENTION
The present invention relates to swimming pool cleaners and, more
particularly,
to automatic swimming pool cleaners driven by the flow of water therethrough
for
purposes of cleaning. Still more particularly, this invention relates to
swimnning pool
pressure cleaners (as opposed to suction-type cleaners) of the type powered by
the
flow of water pumped by remote pumps into and through the pool cleaners.
BACKGROUND OF THE INVENTION
Automatic swimming pool cleaners of the type that move about the underwater
surfaces of a swimming pool are driven by many diil'erent kinds of systems. A
variety
of different pool cleaner drive devices in one way or another harness the flow
of water,
as it is drawn or pushed through the pool cleaner by the pumping action of a
remote
pump for debris collection purposes, to create forward pool cleaner movement.
Some
of the many kinds of water-driven automatic pool cleaners are those driven in
various
ways by turbines, which translate water movement into rotational motion. Wheel
rotation by linkage to a turbine or other drive mechanism causes propulsion in
such
prior art devices. Various problems and shortcoming exist in such prior
devices.
Among the problems and shortcomings not adequately addressed are failures of
certain kinds of cleaners to provide complete cleaning coverage. Obtaining
complete
coverage is particularly difficult or problematic for swimming pools having
certain
kinds of surfaces, surface shapes or obstacles. Complete coverage and
satisfactory
cleaning are difficult to obtain when the pumping pressure generated by the
remote
pump is weak, such that the driving force of a pool cleaner is seriously
diminished.
Various automatic pool cleaners of the prior art have insufficient speed and
strength of
movement, and this creates and exacerbates problems of weak cleaning ability.
Some problems, failures or difficulties occur when pool cleaners get hung up
or
caught at an area where its driving wheels are unable to contact the
underwater pool
surfaces, or are at least unable to engage such surfaces with sufficient
traction to allow
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movement of the pool cleaner. For some cleaners of the prior art, steering
(that is, the
motions taken by pool cleaners in order to change directions) can be
problematic,
particularly on certain kinds of surfaces and when speed is low and the
steering and
propulsion forces that are generated are low.
Certain of these problems are particularly difficult with respect to so-called
"pressure cleaners" - i. e., those pool cleaners the movement of which is
motivated by
the flow of water pumped to the pool cleaner from a remote pump, as opposed to
the
more common suction cleaners, through which water is sucked by a remote pump.
One problem particularly seen with respect to pressure cleaners is difficulty
in
obtaining reliable steering for complete coverage of the underwater surfaces
of a pool.
Steering of certain pressure cleaners of the prior art is typically by
external means.
A brief description of certain swimming pool pressure cleaners of the prior
art
will be helpful. Such pool cleaner includes the pool cleaner unit itself at
the end of a
water-supply hose and a separate box-like control unit along the hose and
spaced from
the pool cleaner unit itself by a distance on the order of ten feet or so. The
pool
cleaner unit itself is a wheeled device which includes a turbine for driving
the wheels,
but does not have any steering apparatus incorporated with it. The box-like
control
unit, which has a second turbine and a sequencing device, periodically shuts
offthe
flow of water to the pool cleaner unit itself and at the same time opens up an
orifice
which shoots a jet of water from the control unit such that the control unit,
acting
through the hose, in effect drags the pool cleaner unit into a different
orientation
and/or position, after which the flow to the pool cleaner unit is
reestablished and the jet
of water from the control unit is stopped.
In such prior pressure cleaning apparatus, water flow to the pool cleaner unit
itself, which has already been used to move a turbine in the control unit, is
split into
two streams -- one for driving the turbine in the pool cleaner unit and one to
establish a
venturi action for drawing water and debris into a flow path leading to a
filter bag or
the like. Due to the prior usage and flow splitting, sometimes including an
additional
separate flow fox the purpose of placing or keeping dirt near the pool cleaner
in
suspension, power for pool cleaner movement is lost and, perhaps more
importantly,
flow fox creating the venturi is limited.
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As a result, the venturi jets) used in such prior systems are made very small -
-
sometimes as low as about 0.100-0.160 inch in diameter -- allow development of
high
linear flow velocities of water from the venturi jet(s), despite the low flow
volume.
Low flow volumes and very localized venturi effects limit pool cleaning
effectiveness
in such prior pool cleaners. One specific result of the low flow volumes from
the
venturi jets) is that the opening for inflow of water and debris is more
limited in size
than is desirable. Thus, the inflow of debris and the size of the debris which
can be
collected are more limited than is desirable.
Other problems and shortcomings are associated with such apparatus. Control
of the pool cleaner at best tends to be rather ineffective, resulting in
ineffective
coverage of the surfaces of a pool. Furthermore, because of division of water
flow
from the hose, the water available to operate the principal turbine of the
apparatus is
reduced, and this in turn reduces the strength of travel of the pool cleaner
unit and
detracts from its cleaning power.
While various advances have been made in the field of automatic swimming
pool cleaners, including pressure cleaners, as of this writing there remains a
need for an
pressure cleaner for swimming pools which is internally self steerable. More
generally,
there is a need for automatic pool cleaners with improved functionality to
address the
problems referred to above.
OBJECTS OF THE INVENTION
It is an object of this invention to provide an improved swimming pool cleaner
pressure cleaner of the automatic water-driven type which overcomes some of
the
problems and shortcomings of the prior art.
Another object of this invention is to provide an improved water-driven
swimming pool pressure cleaner having an internal steering mechanism.
Another object of the invention is to provide an improved water-driven
swimming pool pressure cleaner giving excellent coverage and cleaning of
underwater
pool surfaces, including hard-to-reach areas.
Another object is to provide an improved water-driven swimming pool pressure
cleaner with highly reliable self steering.
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Another object of the invention is to provide an improved water-driven
swimming pool pressure cleaner which has excellent traction in a variety of
situations.
Another object of this invention is to provide an improved water-driven
swimming pool pressure cleaner able to utilize a greater portion of flow from
the
remote pump, and a greater portion of the power of the flow from the remote
pump, to
create venturi action for picking up debris.
Another object of this invention is to provide an improved water-driven
swimming pool pressure cleaner with larger inflow openings for water and
debris and
an increased venturi effect in drawing of unwanted debris into a collector.
Another object of this invention is to provide an improved water-driven
swimming pool pressure cleaner which can operate effectively at lower
pressures than
many pressure cleaners of the prior art.
Still another object of the invention is to provide an improved water-driven
swimming pool pressure cleaner which has excellent ability to traverse pool
surfaces of
different types and hard-to-reach pool areas.
Another object of the invention is to provide an improved water-driven
swimming pool pressure cleaner which generates good driving power even when
used
with pool pumping systems generating low pumping pressures.
Another object of the invention is to provide an improved water-driven
swimming pool pressure cleaner which resists any tendency to become hung up
and is
capable of extracting itself from situations in which there is a lack of
traction.
Still another object is to provide an improved water-driven swimming pool
pressure cleaner with excellent speed and steering (direction-changing)
capabilities.
These and other objects of the invention will be apparent from the following
descriptions and from the drawings.
SUMMARY OF THE INVENTION
This invention is an improved swimming pool pressure cleaner of the type
motivated by water flow through it to move along a pool surface to be cleaned.
The
invention, including in its preferred embodiments, overcomes various problems
and
shortcomings of the prior art, including those referred to above. The
invention is a
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pressure cleaner for swimming pools which incorporates within itself apparatus
which
provides self steering,
The swimming pool pressure cleaner of this invention provides many important
advantages, including the following: compactness in a pressure cleaner with
steering
by virtue of the inclusion of steering apparatus in a single structure;
excellent coverage
of underwater surfaces; highly-reliable self steering; improved take-up of
debris; a
larger inflow opening for debris; better utilization of water flow, for
purposes of
propulsion, steering and take-up of debris; effective pool cleaner operation
at low
pressure; excellent traction; ability to avoid and/or escape situations
involving hang-up
of the pool cleaner; and excellent speed and power.
The swimming pool pressure cleaner is a pressure cleaner of the type including
a body, wheels rotatably mounted to the body, a turbine housing having a water-
flow
chamber formed by a chamber wall and having an inlet and an outlet, a turbine
rotor
rotatably mounted in the chamber and having vanes, a drive member secured to
the
rotor and a drive train from the drive member to drive the wheels on
underwater pool
surfaces, a venturi jet and a water conduit to feed water to the venturi jet
from a hose.
In the inventive pool cleaner, the turbine inlet is supported in close
proximity to
the pool surface and the venturi jet is located at the turbine inlet, oriented
to direct
water into the turbine inlet -- to both rotate the turbine and cause water and
debris to
flow from the pool past the venturi jet and into the inlet, by means of
venturi action.
The pool cleaner also includes a steering mechanism secured to the body and
having a
movable part which periodically interrupts the synchronous rotation of the
wheels on
the pool surface, thereby causing changes in the direction of pool cleaner
travel.
The steering mechanism in the pool cleaner of this invention is sometimes
referred to as "internal." The pool cleaners of this invention are compared to
pressure
cleaners having an additional apparatus which may be said to provide some
"steering"
for a pool cleaner. But such additional apparatus is separate from the pool
cleaner and
linked to it only by a length of flexible hose by which the additional
apparatus pulls the
pool cleaner unit in various directions. With this in mind, the term
"internal" as used
herein means "affixed thereto as a part thereof." Thus, the term "internal"
does not
carry with it the idea that the steering mechanism is enclosed to any extent.
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In highly preferred embodiments, the steering mechanism includes: a cam
having portions of greater and lesser radii which is rotatably secured to the
body and
driven by the rotor through reduction gearing; and linkage from the cam to a
wheel to
periodically interrupt synchronous rotation of the wheels on the pool surface.
In more detail, the device of this invention includes: a body having front,
rear
and opposite sides; a set of two wheels rotatably mounted to the body, one on
each
side; a turbine housing secured to the body and having a water-flow chamber
formed
by a chamber wall, the chamber having an inlet and an outlet, the inlet
supported in
close proximity to the pool surface; a turbine rotor rotatably mounted in the
chamber,
the rotor having vanes; one or more venturi jets secured to the body and
oriented to
direct water into the inlet to rotate the turbine and cause, by virtue of the
venturi
action, a flow of water and debris from the pool into the inlet; one or more
water
conduits to transmit water from a hose to the one or more venturi jets; a
drive member
secured to the rotor and rotatable with the rotor; a drive train from the
drive member
to the~wheels for synchronous rotation of the wheels on the underwater pool
surfaces;
a cam having portions of greater and lesser radii, the cam being rotatably
secured to
the body and driven by the rotor through reduction gearing; and a linkage from
the
cam to one of the wheels to periodically interrupt the synchronous rotation of
the
wheels on the pool surface and thereby change the direction of pool cleaner
movement.
The water conduit transmitting water to the venturi jets is fed by a flexible
hose
which is attached in fluid-flow relation to an upstream end of the conduit
hose. Water
is supplied under pressure from a remote pump through the hose, through a
rotatable
cylindrical sleeve mount on the housing, in well-known fashion.
In preferred embodiments, there are a plurality of spaced venturi jets.
Multiple
jets improve the venturi action which draws water and debris from near the
underwater
surfaces of the pool into the pool cleaner -- and ultimately into a filter
attached to the
pool cleaner. The presence of two or three venturi jets is preferred, and the
spacing
not only provides more venturi action but serves to provide space to
facilitate flow of
debris into the inlet. At least one of the venturi jets is preferably oriented
toward the
outlet to provide an accelerated flow of water directly toward the outlet.
Preferred
embodiments of this invention include a debris-capturing bag secured to the
outlet.
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~rcrvv~ 1 a ~r~v GUUI
The improved pressure cleaner of this invention provides excellent power and
drive particularly when the turbine is in the highly preferred forms which are
the
subject of United States Patent No. 6,292,970, entitled "Turbine-Driven
Automatic
Swimming Pool Cleaners," to Dieter 1. Rief and Manuela Itiei~ the inventors
herein,
and Rosemarie Rief.
In such prefer ed form, the turbine vanes have proximal ends connected to the
rotor and distal ends movable with respect to the rotor between extended
positions
adjacent to the wall of the turbine chamber and retracted positions which are
spaced
from the wall and closer to the rotor. Preferably, the turbine vanes are
pivotably
mounted with respect to the rotor, and most preferably the turbine vanes are
curved
and have distal edges which contact the chamber wall in their extended
positions, at
least in certain positions about the rotor. A preferred form of rotational
mounting of
the vanes is as follows: The rotor has an exterior surface beneath which, for
each
vane, there is a corresponding cavity which pivotably holds the proximal end
of the
vane. Enlargements at the proximal ends of the vanes are sized for free
insertion into,
and pivotable engagement in, the cavities within the rotor.
Each wheel, of course, has an inward side and an outward side depending upon
how it is mounted on the pool cleaner. In prefernd embodiments of this
invention, the
first wheel of the set has radially-spaced primary and secondary wheelgears on
its
inward side, such wheelgears facing one another, and the second wheel of the
set has
another primary wheelgear on its inward side, the primary wheelgears on the
two
wheels being similar to one another. Preferably, the drive train terminates at
the first
and second wheels in first and second drive pinions, respectively, each
engaging the
primary wheelgear of the respective wheel; this serves to drive the wheels in
the
forward direction synchronously, in contact with the underwater pool cleaner
surface
In such embodiments, it is preferred that the wheelgears of the first wheel be
concentric, and integrally formed with the &rst wheel itself. The wheelgear of
the
second wheel is also preferably integrally formed with the second wheel. Most
preferably, the first and second wheels are identical, and therefore
interchangeable.
As used herein, the term "wheelgear" refers to any gear which is afiix~i on,
or
formed as part of, a swimming pool cleaner wheel which contacts the surface of
the
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pool to propel the pool cleaner. Among the wheelgears referred to herein are
the
aforementioned primary and secondary gears and, as will be seen below, gears
referred
to as "final" wheelgears.
In preferred embodiments, the drive member is a drive gear and the drive train
includes first and second drive shafts which are journaled with respect to the
body and
which have proximal and distal ends. In such embodiments, the first and second
drive
pinions, mentioned above, are driven by the first and second drive shafts,
respectively,
and the drive train is a gear train from the drive gear to the first and
second drive
shafts. Preferably, the first and second drive shafts form the first and
second drive
pinions, respectively, at their distal ends.
The drive train preferably includes a coupler with opposite ends receiving the
proximal ends of the first and second drive shafts. The proximal end of the
first drive
shaft is a ball joint which allows the first drive shaft to be pivoted ofd
axis. This allows
the distal end of the first drive shaft to be moved fore and aft between a
driving
position in which the first drive pinion engages the primary wheelgear of the
first wheel
and a steering position in which it engages the secondary wheelgear of the
first wheel.
This movement, from engagement with a wheelgear in the form of a ring gear
(with
inwardly-facing teeth) to engagement with a wheelgear having outwardly-facing
teeth,
causes the first wheel to change its direction of rotation -- i.e., to rotate
in a direction
opposite that of the second wheel. This interrupts the synchronous rotation of
the
wheels on the pool surface, and causes turning of the pool cleaner.
The rotatable cam (a timing cam) mentioned above serves to provide steering
of the pool cleaner; in one way or another it causes interruption of
synchronous
rotation of the first and second wheels on the pool surfaces. In certain
preferred
embodiments, the linkage from the cam to the first wheel includes a shift
bracket
assembly which is slidably held by the body in a position such that the first
drive shaft
is journaled in it, thereby to allow movement of the distal end of the first
drive shaft
between driving and steering positions, by movement of the shift bracket
assembly.
The cam wheel engages the shift bracket and a spring biases the shift bracket
toward the cam wheel, such that the cam wheel, acting through the shift
bracket
assembly, provides the fore-and-aft movement by alternately (a) holding the
distal end
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of the first drive shaft in the driving position and (b) allowing the distal
end of the first
drive shaft to move to the steering position by virtue of the action of the
spring.
The rotatable cam can interrupt synchronous rotation of the first and second
wheels on the pool surfaces in other ways. One example of other forms of
interruption
involves a temporary lifting of one wheel from the surface of the pool when a
cam
portion of larger radius (larger than most of such cam) engages the pool
surface and
props one side of the pool cleaner away from the pool surface. In such
example, even
though the first and second wheels may continue to turn synchronously, they
will not
be turning synchronously on the pool surface; synchronous rotation on the pool
surface
is restored when the cam is no longer lifting one side of the pool cleaner.
In highly preferred embodiments, the wheels have treads with a multiplicity of
outwardly extending radial fingers. It is most preferred that a small subset
of the radial
fingers (extending along a very small sector of the wheel) project radially
farther than
the other fingers. With this embodiment, if the pool cleaner for any reason is
hung up
on some obstruction or pool surface feature, the longer treads, when they come
around, tend to provide traction for dislodgement purposes.
Certain highly preferred embodiments include a second set of wheels, once
again including one wheel on each side of the pool cleaner. The wheels of the
second
set are preferably aft of the wheels of the first-mentioned set. Each of the
wheels of
the second set has what is being called a "final" wheelgear on its outward
side. In such
embodiments, there is an extended drive train for each of the wheels of the
second set,
and each such extended drive train includes a transfer shaft journaled with
respect to
the body, a first transfer pinion engaged with one of the primary wheelgears,
and a
second transfer pinion engaged with one of the final wheelgears. These
extended drive
trains serve to impart rotation to the wheels of the second set, having
transferred
rotational movement from the wheels of the first wheel set. Preferably, each
transfer
shaft itself forms the first and second transfer pinions at the opposite ends
thereof.
In pressure cleaners with more than two wheels, it is preferred that all
wheels,
including those having "final" wheelgears on them, have wheelgears integrally
formed
with the wheel. Most preferably, all four wheels (or whatever number there are
greater
than two) are identical so that they can be completely interchangeable.
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The preferred four-wheel-drive pressure cleaner for swimming pools is among
the subjects of PCT Patent Application No. PCTILTS00114771, entitled "Four-
Wheel-
Drive Automatic Swimming Pool Cleaner," for an invemion of Dieter J. Rief and
Manuela Rief, the inventors herein.
In certain preferred embodiments, the aforementioned water inlet faces the
surface of the pool and the device includes a skirt secured with respect to
the body and
extending toward the pool surface such that the skirt and the body, together
with the
pool surface, form a plenum from which water and debris are drawn into the
inlet. The
skirt is formed of at least one flap member which has upper and lower
articulating
portions, the upper articulating portion having a proximal edge hinged to the
body and
a lower alge hinged to the lower articulating portion. Most preferably, the
skirt is
segmented in that it is formed of a plurality of the articulated flap members
in side-by-
side arrangement, each having upper and lower articulating portions.
Such skirt, which is the subject of commonly-owned copending United States
Patent No. 6,131,227, entitled "Suction-Regulating Skirt for Automated
Swiminimg
Pool Cleaner Heads," to Dieter J. Rief, an inventor herein, and Hams Raines
Schlitzer,
facilitates relative enclosure of the plenum despite encountered
irregularities in the
pool surface immediately under the pool cleaner. As water is drawn into the
turbine
chamber through the inlet, the skirt minimizes the openness between the pool
cleaner
body and the underwater surface of the pool, and this causes a speed-up in the
linear
A
flow of water immediately along the underwater surface of the pool, at
positions under
the pool cleaner. Such speed-up of linear flow improves the ability of the
pool cleaner
to ingest debris along with water, so that the debris tends to move easily
into the
turbine chamber, and from there through the outlet and into a bag or other
collector.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a perspective view of a preferred automatic pool cleaner in
accordance with this invention, taken generally from the rear. The device is a
suction
cleaner.
FIGURE 2 is a front elevation of the device of FIGURE I .
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FIGURE 3 is a left side elevation of the device of FIGURE 1.
FIGURE 4 is a rear elevation of the device of FIGURE 1.
FIGURE 5 is a top plan view of the device of FIGURE 1.
FIGURE 6 is a detailed top sectional of the device of FIGURE 1.
FIGURE 7 is a schematic sectional side elevation illustrating aspects of the
turbine portions of another embodiment of the invention, a swimming pool
pressure
cleaner.
FIGURE 8 is a perspective of one of the drive wheels, with its annular tread
piece removed.
FIGURE 9 is a perspective of the tread piece.
FIGURE 10 is a perspective view of another preferred swimming pool pressure
cleaner in accordance with this invention, a pool cleaner having only two
wheels.
DETAILED DESCRIPTION OF PREFERRED EMBODIIVVIENTS
FIGURES 1-9 illustrate a preferred swimming pool pressure cleaner cleaner 20
in accordance with this invention. Pool cleaner 20 has four identical drive
wheels
marked by numeral 22, including left front drive wheel 22a, right front drive
wheel
22b, and left and right rear drive wheels 22c and 22d. All four drive wheels
are driven
to provide forward movement of pool cleaner 20. Rear drive wheels 22c and 22d
are
driven by separate linkages from front wheels 22a and 22b, respectively.
Left front drive wheel 22a, which is normally driven in a forward direction,
is
periodically temporarily driven in a reverse direction. When this occurs, left
rear drive
wheel 22c is also driven in a reverse direction by virtue of the linkage
between drive
wheels 22a and 22c. During such brief intermittent periods of reverse
rotation, the
direction of travel of pool cleaner 20 changes. This steering function,
together with
the power provided by four-wheel drive of this invention, provides excellent
cleaning
coverage of underwater pool surfaces 54.
Pool cleaner 20 includes a body 24 preferably formed of two or more plastic
pieces designed to accommodate the parts and features of the invention. Front
drive
wheels 22a and 22b are rotatably mounted to body 24 on wheel shafts 26, as
shown in
FIGURE 6. Attached to body 24 are rear wheel supports 28, and rear wheels 22c
and
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22d are rotatably mounted thereon by wheel shafts 30. Front wheels 22a and 22b
have
gearing (hereafter described) on their inward surfaces, i. e., the surfaces
facing each
other. Rear wheels 22c and 22d have the same gearing on their outward
surfaces.
Drive wheels 22a-d are identical to each other, and thus are interchangeable.
The gearing on wheels 22a-d includes concentric radially-spaced primary and
secondary wheelgears 32 and 34. Primary and secondary wheelgears 32 and 34 are
radially spaced from one another by a distance in excess of the diameter of a
pinion
gear (hereafter described) which alternately engages such gears on drive wheel
22a.
While all wheels are interchangeable, only drive wheel 22a uses both
wheelgears; on
drive wheels 22b-d, only wheelgear 32 is used.
Pool cleaner 20 has a turbine which uses pressurized flow of water from a hose
to create rotary motion for transfer to the wheels by a drive train. More
specifically, as
shown in schematic FIGURE 7, pool cleaner 20 includes a turbine 36, part of
which,
notably turbine housing 38, is secured to body 24. (As used with respect to
turbine
housing 38 and body 24, the term "secured to" includes having been formed
together.)
Turbine housing 38 has a chamber 40 in it which is formed by a chamber wall
42. Chamber 40 includes an inlet port 70 and an outlet port 72. Turbine 36
also
includes a rotor 48, which is rotatably mounted within chamber 40, and a
number of
turbine vanes 50, each of which has proximal and distal edges SOa and SOb.
Proximal
edge SOa of each vane 50 is generally cylindrical in shape and is loosely
received within
a generally cylindrical void in rotor 48, formed just below the outer surface
of the
rotor. Thus, vanes 50, which are of a curved configuration, freely move
between fully
extended positions in which they contact chamber wall 42 and retracted
positions in
which their distal edges SOb are closer to rotor 48 and spaced from chamber
wall 42.
This provides free adjustability of vanes 50 to facilitate passage of large
pieces of
debris to pass through chamber 40 without interfering with operation of the
turbine.
Chamber 40 is of substantial size to further facilitate flow of debris.
Swimming pool pressure cleaner 20, as illustrated in FIGURE 7, operates by
receiving a flow of water through a flexible pool cleaner hose (not shown),
which is
attached to a swiveling hose coupling 75, shown in FIGURES 1, 4 and 5 (and not
shown in FIGURE 7) in well-known manner. The water from the hose flows through
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conduits 64 and conduit branches 64a and 64b, and ultimately through venturi
jets 66a
and 66b into turbine 68. Conduit 64 and conduit branches 64a and 64b, which
are
illustrated schematically in FIGURE 7, extend within body 24 around turbine
housing
38 by means of channels (not shown) formed in the housing or flexible hose
(not
shown). It should be remembered that FIGURE 7 is schematic; it omits a number
of
parts and does not purport to show the location or structure providing
conduits for
flow of water from the hose to the venturi jets.
As shown in FIGURE 7, turbine 68 has a large inlet 70 facing the pool surface
54; inlet 70 is larger than openings in certain prior pressure cleaners.
Venturi jets 66a
and 66b are at or near inlet 70 and are oriented to direct water upwardly into
inlet 70
and toward outlet 72. Venturi jets 66a and 66b, particularly 66a, are located
to cause
rotation of rotor 48 of turbine 68 to provide driving. and steering power for
pressure
cleaner 20. A venturi action caused by venturi jets 66a and 66b draws water
and
debris from beneath pool cleaner 20 through inlet 70, turbine 36 and outlet
port 72 into
a collection bag 74 connected to neck 73. Bag 74 acts as a filter, in known
manner.
The venturi action is caused by the accelerated flow of water created by jets
66a and 66b. The accelerated flow of water creates a pressure differential
which
causes an upward suction of water and debris from adjacent to pool surface 54
into
inlet 70. Thus, the venturi jets serve two purposes -- driving the turbine and
creating
an upward flow from beneath the pool cleaner for cleaning purposes. The size
and
orientation of venturi jets 66a and 66b not only cause these actions, but
serve to
facilitate an essentially quick straight-line movement of debris into
collection bag 74.
Turbine 36 serves two functions, providing power to drive wheels 22a-d
through linkages (hereafter described) and providing power for operation of a
steering
device (hereafter described), both of which occur as water and debris are
drawn
through it by the above-described venturi action. The water pressure for
pressure
cleaner 20 is supplied by a remote pump, in known fashion.
Beneath pool cleaner 20, water inlet 70 faces underwater pool surface 54.
Pool cleaner 20 includes a segmented skirt which has forward and rearward
portions,
each of which includes a number of flap members 56 arranged in side by side
relationship. Together, flap members 56, body 24 and pool surface 54 form a
plenum
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62. Each flap member 56 includes an upper articulating portion 58 and a lower
articulating portion 60. Upper portion 58 has a proximal end 58a which is
hinged to
body 24 and a distal end 58b which is hinged to a proximal end 60a of upper
portion
60. By virtue of this design, flap members 56 self adjust to the contours of
pool
surface 54. Flap members 56 serve to keep plenum 62 substantially closed,
which
provides flow characteristics favorable for collection of debris from beneath
pool
cleaner 20 by the venturi action.
The following is a description of the manner in which the rotation of rotor 48
is transmitted to drive wheels 22a-d. FIGURE 6 is particularly helpful in
illustrating
the drive train and its three different portions. The three different portions
include: (I)
a first portion which extends from a first drive gear 76, affixed to rotor 48,
to left and
right front wheels 22a and 22b; (2) a second portion which extends from front
wheel
22a to rear wheel 22c; and (3) a third portion which extends from front wheel
22b to
rear wheel 22d. (The second and third portions of the drive train are
identical to each
other.) All four wheels are driven by first drive gear 76; a second drive gear
78, which
is affixed to the opposite side of rotor 48, is used to control the steering
of pool
cleaner 20. (First and second drive gears 76 and 78 are integrally formed with
rotor 48
and are affixed to a rotor shaft 79 which is rotatably mounted with respect to
body 24.)
The first drive train portion includes left and right drive shafts 80 and 82,
sometimes referred to as "first" and "second" drive shafts. They are in end-to-
end
alignment. The first drive train portion also includes a gear train having
gears 84a, 84b
and 84c. Gear 84c also serves as a coupler receiving the proximal ends 80a and
82a of
drive shafts 80 and 82. (Proximal end 80a of drive shaft 80 forms a ball joint
coupling
with coupling gear 84c, for steering-related purpose described below.) Drive
shafts 80
and 82 terminate at their distal ends in pinion gears 86a and 86b, which are
integrally
formed with the shafts. Pinion gears 86a and 86b engage primary wheelgears 32
of
drive train wheels 22a and 22b, respectively. Thus, the rotation of rotor 48
causes
synchronous rotation of front drive wheels 22a and 22b, each in the same
direction.
The rotation of front drive wheels 22a and 22b causes rotation of rear drive
wheels 22c and 22d, by means of the second and third drive-train portions,
which are
now described. Each of these identical drive-train portions ends up engaging
primary
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(or final) wheelgear 32 of one of rear drive wheels 22c and 22d. Adjacent to
each rear
wheel is a transfer shaft 88 journaled in body 24 by means of appropriate
bearings.
The opposite ends of each transfer shaft 88 include pinion gears 90a and 90b,
which
are formed as part of transfer shaft 88. Each pinion gear 90a engages primary
wheelgear 32 of one of front drive wheels 22a or 22b, at a position spaced
about 180°
from the point of engagement of pinion gear 86a or 86b therewith. Each pinion
gear
90b engages primary (or final) wheelgear 32 of one of rear drive wheels 22c
and 22d.
The operation of the steering mechanism will now be described. Left drive
shaft 80, which is generally in exact axial alignment with right drive shaft
82, can be
moved ofd axis by virtue of the ball joint at its proximal end 80a. More
specifically,
pinion gear 86a, which is formed at the distal end of left drive shaft 80, is
movable in
fore-and-aft directions depending upon forces applied to drive shaft 80, as
hereafter
described. FIGURE 7 shows an oblong opening 92 in a portion of body 24 which
accommodates such movement of left drive shaft 80.
Pool cleaner 20 includes a shift bracket assembly 94 slidably held within a
cavity 96 formed in body 24. Drive shaft 80 is journaled by a suitable bearing
in shift
bracket assembly 94. Shift bracket assembly 94 includes a roller 98 at its
rear end for
engagement by a cam wheel 100 that serves the purpose of controlling the fore-
and-aft
position of shift bracket assembly 94. A spring 102 is located within cavity
96 in a
position between a fixed surface of body 24 and the front end of shift bracket
assembly
94. Spring 102 biases shift bracket assembly 94 into engagement with cam wheel
100.
Since left drive shaft 80 is journaled in shift bracket assembly 94, the
position
of pinion gear 86a is determined by the fore-or-aft position of shift bracket
assembly
94. In the forward position, pinion gear 86a engages primary wheelgear 32 of
left
front wheel 22a; in the rearward position, it engages secondary wheelgear 34
of left
front wheel 22a. Left front wheel 22a moves in a forward direction when pinion
gear
86a engages primary wheelgear 32; however, since the reverse side of pinion
gear 86a
is what engages secondary wheelgear 34 when pinion gear 86a is in the aft
position,
such engagement results in reverse rotation of left front wheel 22a. And, by
virtue of
the driving linkage between left front wheel 22a and left rear wheel 22c, the
aft
position of pinion gear 86a also reverses the rotational direction of left
rear drive wheel
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22c. In other words, the periodic movement of shift bracket assembly 94 moves
left
drive shaft 80 and its pinion gear 86a to the aft position, and this
interrupts the
synchronous rotation of the drive wheels and causes turning of pool cleaner
20.
A major portion of cam wheel 100 has a fixed radius sufficient to allows cam
wheel 100 to hold shift bracket assembly 94 in a forward position. Cam wheel
100
also has one or more smaller portions of lesser radius which allow shift
bracket
assembly 94 to move to its aft position under the biasing force of spring 102.
Cam wheel 100 is rotatably supported on an extension 104 of rotor shaft 79 at
a position spaced from rotor 48. Also rotatably supported on extension 104 are
several gear members of a reduction gear assembly 106, the purpose of which is
to
reduce rotational speed such that cam wheel 100 turns slowly -- at a rate such
that its
portions of greater or lesser radial dimension dwell in contact with roller 98
of shift
bracket assembly 94 for reasonable periods of time. More specifically, the
gearing and
cam design are such that the pool cleaner 20 will move in a forward position
most of
the time, and only intermittently change directions for short periods of time.
Primary and secondary wheelgears 32 and 34 are integrally formed with each of
the drive wheels 22a-d. FIGURE 8 illustrates the main portion of one such
drive
wheel, with its tread piece removed.
FIGURE 9 illustrates a resilient elastorneric tread element 108 which is
shaped
for firm engagement about the periphery of the main portion of each drive
wheel and
to provide good traction. Tread element 108 has many outwardly extending
resilient
radial fingers 110. These tread features on the drive wheels of the present
invention
provide increased traction on slippery surfaces. This tread in combination
with the
large size of the drive wheels, which are essentially as large in diameter as
the pool
cleaner is high, allows the cleaner to ride over commonly encountered
impediments
and obstacles in the pool environment, including main drains, pool liner
wrinkles, and
uneven, convex and concave surfaces. Such drive wheels in the four-wheel-drive
pool
cleaner of this invention also allow the pool cleaner to navigate a vertical
wall which
joins a pool bottom surface without any curved transition (or "radius").
While elastomeric flexible treads are normally best, in certain applications,
notably involving submerged tile surfaces, it may be preferable to fit the
drive wheels
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with synthetic foam treads. When foam tread is used, effective grip and
suction can be
maintained on even the most slippery submerged inclined and vertical tile
surfaces.
As shown in FIGURE 9, three consecutive radial fingers 110a-c project radially
farther than the others. As explained above, this serves to provide additional
traction
for dislodgement of the pool cleaner 20, if needed. Radial finger 1 l Ob
extends slightly
farther than radial fingers 11 Oa and 1 l Oc.
FIGURE 10 shows a two-wheel swimming pool pressure cleaner 120 in
accordance with this invention. Pool cleaner 120 is powered, supported and
steered by
two, rather than four, drive wheels. Pool cleaner 120 is similar to pool
cleaner 120 in
all significant respects, the principal differences being only that the rear
wheels, the
rear wheel mounts and the rear wheel drive linkages are absent.
Most of the parts of the pool cleaners of this invention may be formed using
rigid plastic parts, as is well known in the art. Suitable materials for all
of the parts
would be apparent to those skilled in the art who are made familiar with this
invention.
A number of variations are possible in design and construction of swimming
pool pressure cleaners in accordance with this invention. The number of
venturi jets
can be varied, either up or down form the two referred to above. Having said
that,
however, it should be pointed out that the use of multiple venturi jets
dramatically
increases the pressure differential between the water in plenum 62 and the
water in the
region immediately above venturi jets 66a and 66b. This allows better pick-up
of
heavier particles of debris.
Likewise, variations in the flow of water between the hose and the venturi
jets
are possible. It is required, however, that the incoming flow of water serve
the dual
purposes of moving the turbine rotor and creating the necessary venturi effect
to cause
the drawing of water and debris into a filter, such as the bag illustrated.
While the principles of this invention have been described in connection with
specific embodiments, it should be understood clearly that these descriptions
are made
only by way of example and are not intended to limit the scope of the
invention.
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