Automatic swimming pool cleaner

An improved swimming pool cleaner of the type for submerged random travel generally along the floor and sidewalls of a swimming pool to dislodge and collect debris. The pool cleaner comprises a frame and associated housing through which a suction mast extends with a collection bag mounted at the upper end thereof. First and second wheels are mounted for rotation on a common axis on opposite sides of the housing forwardly of the suction mast, and third and fourth wheels are mounted for rotation on a common axis on opposite sides of the housing rearwardly of the suction mast. The first and second wheels are driven by a water-powered drive train within the housing, and the third and fourth wheels are mounted for freewheeling rotation. A forward end of an upper surface of the housing has a substantially linear sloping portion to reduce the tendency of the cleaner to lift off the submerged surfaces of the swimming pool as the first and second wheels propel the cleaner in the forward direction.

BACKGROUND OF THE INVENTION 
This invention relates generally to the field of automatic swimming pool 
cleaners, and more particularly, to cleaners of the type for submerged and 
generally random travel along the floor and sidewalls of a swimming pool 
to dislodge and collect debris. 
By way of background, a swimming pool normally includes a water filtration 
system for removing dirt and debris from the pool water. Such filtration 
systems typically include a circulation pump which is installed outside 
the swimming pool and a piping system for coupling the circulation pump to 
the swimming pool. The circulation pump draws water from the swimming pool 
for delivery through the piping system to a filter unit. One or more 
baskets are located in the piping system upstream from the filter unit to 
catch larger debris, such as leaves and the like; the filter unit 
functions to separate dirt and fine debris from the water. The water is 
then recirculated by the pump back to the swimming pool. 
A conventional water filtration system is satisfactory for removing dirt 
and debris of a relatively small size that is suspended in the water, but 
it is not designed to remove larger debris. Such systems depend on the 
aforementioned baskets to prevent larger debris from reaching the filter. 
However, it is generally advisable to clean out such baskets regularly to 
avoid the possibility that they may become clogged, blocking the flow of 
water through the pipes and resulting in damage to the circulation pump. 
Moreover, a conventional water filtration system is not designed to remove 
silt and debris which tends to settle irrespective of size onto the floor 
and sidewalls of a swimming pool. 
To address the foregoing problems, automatic swimming pool cleaners for 
cleaning the floor and sidewalls of a swimming pool are well known. One 
particular type of known automatic swimming pool cleaner is shown and 
described in U.S. Pat. Nos. 3,822,754; 3,936,899; 3,972,339; and 
4,558,479. This type of cleaner has three wheels positioned in a skewed 
triangular arrangement on the outside of a housing, with the housing 
having a front nose set angularly with respect to the direction of cleaner 
movement. An open and generally vertically oriented suction mast defines a 
flow path through the housing, with a collection bag mounted at the upper 
end. 
This type of cleaner operates on pressurized water that is supplied to the 
cleaner through a supply hose. The water is used in part to drive the 
blades of a turbine which, in turn, rotates two or more of the wheels, and 
in part to induce a flow of pool water upwardly through the suction mast 
and into the collection bag. A portion of the pressurized water is also 
supplied through a sweep hose jet to a sweep hose and through a thrust 
jet, both at the rear of the cleaner. A booster pump may be used to 
generate added water pressure for the cleaner, because the circulation 
pump normally used in most swimming pool filtration systems does not 
create sufficient water pressure for all of the above purposes. 
In operation of this type of cleaner, the drive wheels and thrust jet 
propel the cleaner along the floor and sidewalls of the swimming pool. 
When the pool cleaner reaches an obstruction preventing further direct 
forward travel, the skewed drive wheels and angled front nose of the 
cleaner housing imparts a turning movement, causing the cleaner to turn 
and continue travel in a different direction. Alternatively, when the 
cleaner travels along the pool floor and reaches a smoothly curved region 
merging with a sidewall, the cleaner tends to travel through the curved 
region and crawl at least part way up the pool sidewall with 
suction-assisted wheel traction until the cleaner falls by gravity back to 
the floor of the pool. A ballast float mounted at the upper rear of the 
cleaner helps assure that the cleaner will land upright on the pool floor 
and resume travel in a forward direction. As the cleaner travels around 
the pool, it vacuums the larger debris up through the suction mast into 
the collection bag. At the same time, the whipping action of the sweep 
hose sweeps any silt and smaller debris into suspension so that it can be 
filtered out by the pool's filtration system. 
While submerged pool cleaning devices of the foregoing type have performed 
in a generally satisfactory manner, certain shortcomings have been 
observed in available commercial equipment. For example, existing cleaners 
have been constructed on the premise that it is advantageous for all three 
wheels to be driven by the turbine. In order to accomplish this, however, 
the cleaner has used a drive train for the wheels which either has been 
partly exposed to potential jamming or damage from contact with pool 
debris, or has used internal belts that have not proved highly reliable. 
In addition, existing cleaners have not typically been capable in practice 
of climbing the sidewalls of a swimming pool as aggressively as desired. 
For example, instead of the cleaner turning when it reaches a relatively 
sharp transition between the pool floor and a sidewall, it would be 
desirable for the cleaner to continue its forward travel and climb the 
sidewall. Further, it would be desirable for the cleaner to climb the 
sidewall nearly all the way to the waterline. 
Accordingly, a need exists for an improved automatic swimming pool cleaner 
of the type adapted for submerged travel over pool surfaces to collect and 
dislodge debris which is capable of more aggressive climbing of pool 
sidewalls and which has a more reliable drive train that is not as exposed 
to potential jamming or damage from contact with pool debris. The present 
invention fulfills these and other needs. 
SUMMARY OF THE INVENTION 
Briefly, and in general terms, the present invention resides in a novel and 
improved design for an automatic swimming pool cleaner of the type for 
submerged and generally random travel along the floor and sidewalls of a 
swimming pool to dislodge and collect debris. In particular, the cleaner 
includes improved wheel and drive train arrangements and other features 
that result in enhanced climbing ability with a highly reliable drive 
train having virtually no exposure to potential jamming or damage from 
debris. 
The pool cleaner of the present invention comprises a frame which is 
carried by a plurality of wheels and on which is mounted a housing with a 
turbine, water supply means for receiving a supply of water through a 
supply hose, and a vacuum system comprising a suction mast defining an 
open flow path from a lower end positioned generally beneath the housing 
to an upper end disposed generally above the housing, with means for 
inducing a water flow adjacent the submerged surfaces of the swimming pool 
for drawing debris from within the pool into a collection bag mounted at 
the upper end of the suction mast. 
Significantly, in accordance with a primary aspect of the present 
invention, the wheels for the cleaner include first and second wheels 
which are mounted on opposite sides of the housing for rotation about a 
common axis. Drive means are provided to couple the turbine to both the 
first and second wheels for driving rotation to propel the cleaner in a 
forward direction along the submerged surfaces of the swimming pool. The 
first and second wheels are sized and positioned such that they extend 
beyond the forward end of the frame and of the housing. When the first and 
second wheels engage a relatively sharp transition between the pool floor 
and a sidewall, the cleaner tends to continue its forward travel and 
climbs the sidewall, rather than turning and heading off in a different 
direction along the pool floor. 
In the presently preferred embodiment of the invention, the first and 
second wheels are mounted forwardly of the suction mast, thereby providing 
the cleaner with front wheel drive. The turbine may be drivingly coupled 
to the first and second wheels by means of gears that mesh with wheel gear 
means comprising an annular rack formed on an inner surface of the first 
and second wheels. 
The preferred embodiment also has third and fourth wheels mounted on 
opposite sides of the housing rearwardly of the suction mast. The third 
and fourth wheels also may be mounted for rotation about a common axis, 
similar to the first and second wheels. However, in the presently 
preferred embodiment of the invention, the third and fourth wheels are 
mounted for freewheeling rotation, so that all of the motive force of the 
turbine is applied to the front wheels, with no loss of power due to 
friction or slippage that would result from extending the drive train for 
coupling to the rear wheels. Moreover, with this arrangement, the entire 
drive train is substantially enclosed within the housing for shielding 
against significant exposure to debris in the swimming pool, yet the 
cleaner avoids the use of a belt drive type of drive train which has not 
proved to be reliable. 
In a further aspect of the present invention, a forward end of an upper 
surface of the housing is provided with a sloping portion to impart a 
downward force at the forward end of the cleaner to reduce its tendency to 
lift off the submerged surfaces of the swimming pool as the first and 
second wheels propel the cleaner in the forward direction. Preferably, the 
sloping portion of the forward end of the upper surface of the housing 
comprises at least about one-half of the area of the upper surface 
extending forwardly of the suction mast and has a linear slope at an angle 
of about 40 degrees. Alternatively, or in addition, the portion of the 
upper surface of the housing forwardly of the suction mast may be provided 
with a spoiler for the same purpose. 
An automatic swimming pool cleaner in accordance with the present invention 
has enhanced climbing ability, while having a highly reliable drive train 
with essentially no exposure to potential jamming or damage from debris. 
These features and advantages of the present invention should be apparent 
from the following detailed description of the presently preferred 
embodiment, taken in conjunction with the accompanying drawings, which 
illustrate by way of example, the principles of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring now to the drawings, and particularly to FIGS. 1 and 2 thereof, 
there is shown by way of example only a presently preferred embodiment of 
an automatic swimming pool cleaner, indicated generally by reference 
numeral 10, incorporating the principles of the present invention. The 
cleaner 10 includes a frame 12 on which a housing, consisting of an upper 
housing shell 14 and a lower housing shell 16, is mounted. An open suction 
mast 18 for vacuuming debris from beneath the cleaner 10 extends through 
an opening 20, generally in the middle of the upper housing shell 14, and 
a collection bag 22 is attached to the suction mast, over a flapper valve 
24 positioned on the upper end of the suction mast, to collect the debris. 
A pair of opposing jets 26 and 28 are located inside the suction mast 18 
(FIG. 2), near its inlet at the bottom of the cleaner 10, for inducing a 
flow of water upwardly through the suction mast and into the collection 
bag 22 in well-known manner. When the cleaner 10 is operating, the force 
of the water pushes open the flapper valve 24; when the cleaner ceases 
operating, the flapper valve closes by virtue of gravity to keep the 
debris in the collection bag 22 from falling back into the swimming pool 
through the open suction mast 18. 
A vertically oriented supply mast 30 extends through the opening 20 in the 
upper housing shell 14, behind the suction mast 18, to which a supply hose 
32 is connected for delivering pressurized water to the cleaner 10. A 
float 34 is positioned on a support arm 36 formed integrally with, and 
projecting rearwardly from, the supply mast 30, and a sweep hose 38 is 
connected to a sweep hose jet 40 that similarly projects rearwardly from 
the supply mast. In addition, a thrust jet (not shown) is provided at the 
rear of the cleaner 10. 
In accordance with the invention, a first wheel 42 and a second wheel 44 of 
equal size are positioned on opposite sides of the cleaner 10, forwardly 
of the suction mast 18, for rotation on a common axis. A turbine 46 is 
mounted within the frame 12 for producing rotary motion in response to a 
pressured water flow supplied-thereto via hose 48, which connects to an 
outlet 50(FIG. 5) near the base of the supply mast 30, within the cleaner 
housing. The turbine 46 is conventional in design, having a water inlet 
port 52, a water wheel 54, a water outlet port (not shown), and a power 
output shaft 56 which is rotated in response to water being supplied to 
the inlet port 52. 
The power output shaft 56 extends axially in both directions from the 
turbine 46 and is journaled for rotation by nylon bearings 58 in mounting 
blocks 60 which are secured by screws 62 in the sidewalls of the frame 12. 
The opposite ends 64 and 66 of the output shaft 56 have splines formed 
thereon in the nature of gears. Each splined end 64 and 66 of the output 
shaft drivingly engages an annular rack 68 and 70 formed on the inner 
surface of the first wheel 42 and the second wheel 44, respectively, as 
seen in FIGS. 2, 3 and 5. 
The sizes of the first wheel 42 and the second wheel 44, and their position 
relative to the frame 12, are such that both wheels extend in the forward 
direction beyond the forward end of the frame. As a result, when the the 
cleaner 10 approaches a sidewall or other obstruction while being 
propelled in the forward direction, one or both of the first wheel 42 and 
the second wheel 44 will first make contact and cause the cleaner either 
to turn and proceed in a new direction or else to climb the sidewall or 
other obstruction. 
A third wheel 72 and a fourth wheel 74 of equal size are likewise 
positioned on opposite sides of the cleaner 10, rearwardly of the suction 
mast, and rotate on a common axis. However, unlike the first wheel 42 and 
the second wheel 44, neither the third wheel 72 nor the fourth wheel 74 
are driven by the turbine 46. Instead, both the third wheel 72 and the 
fourth wheel 74 are mounted for freewheeling rotation. 
Each of the first wheel 42, the second wheel 44, the third wheel 72 and the 
fourth wheel 74 is mounted on an axle 76, and each wheel is held in place 
on the axle by a hub screw 78 and washer 80 (shown in FIG. 1), 
respectively. As partially shown in FIGS. 2 and 4, each axle 76 is 
integrally molded with a mounting block 82 that is secured in a recess 
formed in the frame 12 by a mounting plate 84 and screws 86. An 
elastomeric tire 88 is mounted on each wheel. 
Although a detailed plan view of the frame 12 is not illustrated in the 
drawings, it is contemplated that many openings will be formed in the 
frame over its lateral and longitudinal extent in order to make it as 
lightweight as practicable, consistent with maintaining appropriate 
structural strength. These openings in the frame 12 also serve to prevent 
air from becoming trapped in the cleaner 10 when it is first submerged in 
the swimming pool, causing the cleaner to float undesirably. At the same 
time, however, it is also contemplated that a brass weight (also not 
shown) will be mounted at the forward end of the frame 12 to increase the 
traction of the first and second wheels 42 and 44. Of course, the float 34 
also has the effect of increasing the traction of the first and second 
wheels 42 and 44 by virtue of the relatively high elevational positioning 
of the float 34 at the rear of the cleaner 10. 
Referring again to FIGS. 1, 2 and 5, the forward end portion of the upper 
housing shell 14 includes a sloping portion 90. This sloping portion 90 
comprises a substantially flat or linear surface having an angle of about 
40 degrees to the horizontal plane of the cleaner 10 and comprises about 
one-half of the area of the surface of the upper housing shell 14 
extending forwardly of the suction mast 18. As the cleaner 10 is propelled 
in the forward direction, the force of the water in the swimming pool on 
this sloping portion 90 advantageously tends to push the front of the 
cleaner in a downward direction. This downward force, in conjunction with 
the downward force of the aforementioned brass weight and the 
counterbalancing force applied by the float 34, farther increase the 
traction of the first and second wheels 42 and 44 and reduces the tendency 
of the front of the cleaner 10 to lift off the submerged surfaces of the 
swimming pool as the cleaner is propelled in the forward direction. 
For additional traction and reduction of the tendency of the front of the 
cleaner to lift, a spoiler 92 in the form of a relatively long and narrow 
vee-shaped plate is shown mounted on the upper housing shell 14 forwardly 
of the suction mast 18. As shown in FIG. 7, for convenience of fabrication 
the spoiler 92 can be formed as a separate part and mounted with a snap 
fit in openings 94 formed in the upper housing shell 14. 
Based on the foregoing, it will be appreciated that an improved swimming 
pool cleaner has been shown and described that has enhanced climbing 
ability and a highly reliable drive train which is substantially encased 
within the cleaner housing such that the drive train has virtually no 
exposure to potential jamming or damage from debris. It will further be 
appreciated that there may be many configurations for a swimming pool 
cleaner in which the principles of the present invention are applicable. 
Therefore, the scope of the present invention should not be seen as 
limited except by the following claims.