US 5737791 discloses a pool cleaner with a body in which is formed a passage with
a restricted throat. A valve element in the form of shuttle extends laterally to the
throat and is movable to block fluid flow through the throat. The valve member is
however not positioned inside the passage nor in the throat.
SUMMARY OF INVENTION
The present invention is concemed, in the first instance, with a pool cleaner body
which lends itself to facilitating the manufacture thereof as an integral structure.
Inherent in the nature of an integral pool cleaner body is the incorporation of a
flotation device in the body. The applicant has discovered that this feature can be
utilised to produce important benefits and hence a second aspect of the invention
relates to characteristics of the flotation means which allow such benefits to be
produced.
To achieve the aforementioned and other objects the invention provides a pool
cleaner which includes a body, at least one passage which extends through the body
with an inlet to the passage and an outlet from the passage at respective opposed
ends of the passage and a fluid flow interrupting device in the passage, the passage
having a minimum cross-sectional area at a position selected from the inlet, the outlet,
and a location between the inlet and the outlet, the cross-sectional area of the
passage in each direction extending away from the said selected position towards
each respective end of the passage monotonically increasing in magnitude.
"Monotonic", as used herein, indicates that the cross-sectional area of the passage
at any location is greater than or equal to the cross-sectional area of the passage at
a preceding adjacent location, moving away from the position of minimum cross-sectional
area. Thus, although the cross-sectional area may not increase along its
length, in the indicated direction, it does not decrease. This enables the passage to
be formed using a single core which does not have any undercut sections or steps
which could impede withdrawal of the core from the passage.
Preferably the said position of minimum cross-sectional area is at the outlet. This
enables a single core to be used for forming the passage, as opposed to two cores
which are movable together in opposite directions to a moulding position.
The pool cleaner may include a partition which divides the passage into first and
second adjacent sub-passages. This however depends on the nature of the cleaner.
The partition, when used, may be formed integrally with the remainder of the body.
This may be done by appropriately shaping the core. Preferably though the partition
is formed separately from the body and is engaged with formations in the body
thereby to divide the passage into the said first and second adjacent sub-passages.
The pool cleaner may include a chamber adjacent the inlet which is in communication
with the passage, with the fluid-flow interrupting device, which may be of any
appropriate kind, in the chamber. A closure member with at least one aperture may
be releasably engaged with the body to enclose the device in the chamber.
The closure member is preferably formed so that a gap is formed between a surface
of the dosure member and an opposing surface of the fluid-flow interrupting device.
Preferably the width of this gap is approximately equal to the maximum width of an
opening formed between the fluid-flow interrupting device and an inner wall of the
chamber as the device moves, during use of the pool cleaner.
The closure member may be domed or have any other suitable shape, or be fixed to
the body of the cleaner in any appropriate way, to achieve the aforementioned
feature.
The cleaner may include flotation means which may be elongate, extending in the
general direction of the passage, and which has a length which is in excess of 25%
of the length of the body, and which is preferably of the order of 50% of such length.
In a variation of the invention the flotation means comprises a plurality of flotation
components which are respectively positioned at spaced intervals from each other in
an array which extends in the general direction of the passage between the inlet and
the outlet.
The flotation means may be formed separately and may then be embedded in the
body during manufacture of the body. According to a preferred aspect of the invention
however the flotation means is formed integrally with the body by foaming material
from which the body is made during manufacture of the body.
As used herein "foaming" includes any mechanism or technique whereby the material
of the body is directly caused to foam, by means of chemical action, or the material
is foamed by the introduction of a foaming agent of any appropriate kind or is aerated,
for example by the injection of a suitable gas, including air.
The flotation means is preferably located on what in use is an upper side of the body,
on one side of the passage, and biasing means which may be in the form of a body
section is then located on a lower side of the body on a directly opposing side of the
passage.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is further described by way of examples with reference to the
accompanying drawings in which:
Figure 1 is a side view of a pool cleaner according to the invention in the process of
manufacture; Figure 2 is a perspective illustration of a core used in the process of manufacture; Figure 3 is an end view of a mouth of the pool cleaner shown in Figure 1; Figure 4 is a cross-sectional view of a body of the pool cleaner taken on a line 4-4
in Figure 1; Figure 5 is a perspective view of a partition and hammer used in the pool cleaner of
the invention; Figure 6 is an end view of the body of the pool cleaner with a cover plate in an
exploded position; Figure 7 is a cross-sectional side view of a modification of the pool cleaner; Figure 8 is a front view of the modification of Figure 7; Figure 9 is a view of a pool cleaner body which is similar to that shown in Figure 1 but
which includes a variation of the invention; Figure 10 is a side view of a pool cleaner according to a different form of the
invention; Figure 11 illustrates a flow interrupting device which is used in the pool cleaner of
Figure 10; and Figure 12 shows the components of Figures 10 and 11 assembled.
DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 1 of the accompanying drawings illustrates a pool cleaner body 10 in the
process of manufacture. The body is formed inside a first mould member 12 which
is made from a suitable material and in which is located a second mould member 14
referred to herein as a core. The mould member 12 is made from at least two
interengageable halves. To a considerable extent Figure 1 is schematic for it is
intended to show the principles of the process of manufacture. The manner in which
the mould members are made and engaged with one another are aspects which are
known in the art and hence are not further described herein.
The core 14 is precisely positioned inside a cavity 16 which defines an outer shape
of the body 10. This is done using techniques which are known in the art. A suitable
plastics material such as polypropylene is then injected into the cavity around the core
14 to form the body 10. Once the body has set the body is removed from the mould
member 12 and the core 14 is extracted. All this is done using techniques which are
known in the art.
An objective of the present invention is to provide a pool cleaner body which is formed
in a single moulding process so that, as far as possible, the body has a unitary type
construction. In other words components which make up the body are not separately
fabricated and then secured to one another by means of fasteners, clip formations and
the like. It is important, particularly from the economic point of view and from the
durability point of view, to be able to make a pool cleaner body which has a unitary
construction. Production costs are low and the ability of the body to withstand
vibration and similar shock effects, which may be encountered during use, is
enhanced.
It is known that a pool cleaner, during use, should adopt a designed orientation. For
this purpose use is made of a flotation component which imparts buoyancy to the
body and a biasing member or weight which increases the density of a portion of the
body. Hitherto, to the applicant's knowledge, pool cleaners of which the applicant is
aware make use of a flotation component which has a "localised effect. For example
in US 4023227 the flotation component is circular, viewed from the side. In US
4351077 the flotation component is spherical. The applicant has now discovered that
the use of an elongate flotation component holds two important benefits. Firstly the
orientation of the cleaner, which is essential for good working and particularly when
the cleaner is first immersed in water, is maintained with a surprising degree of
accuracy. An unexpected result, the reasons for which are not fully understood, is
that weights which are normally attached to a suction hose connected to the cleaner
may be dispensed with. Such weights are traditionally used in a manner which is
determined empirically and which depends inter alia on the depth of the swimming
pool in which the cleaner is used.
A second benefit is that the applicant has noticed that the pool cleaner body is highly
manoeuvrable during use. The pool cleaner body is able to rotate in a manner which
reduces the likelihood that the pool cleaner will become trapped at awkward locations
under water, for example at corners or steps.
To achieve the aforementioned benefits the pool cleaner body 10 includes an
elongate flotation component 18 which, in this example of the invention, is
prefabricated from a suitable foamed material such as polystyrene or foamed
polyurethane or any equivalent material. The pool cleaner body also includes a lead
weight or bias component 20 embedded in the body.
The core 14 is shown in perspective in Figure 2. The core has a central section 22
which is elongate and which has a circular cross-section, a spigot 24 at one end of the
central section and an enlarged chamber- forming section 26 at an opposed end of
the central section. Two ribs 28 project outwardly from the central section 22 and
extend between the spigot 24 and the section 26. The ribs are on opposed sides of
the central section. Only one rib is visible in Figure 1 and Figure 2.
The central section of the core is formed with a first pair of recesses 30 on one side
thereof and a second set of recesses 32 on an opposing side thereof (see Figure 1).
Before the core is located in the mould member 12 small plastic spigots 34 are
inserted into the respective recesses. Protruding ends of the spigots are engaged
with complementary holes in the flotation component 18 and the lead weight 20,
respectively. In this way the flotation component and the lead weight are precisely
positioned relatively to the core. The core is then located in the mould member 12.
The core extends between opposed ends 36 and 38 of the body and, once removed,
leaves a passage 40 which extends between these ends. The passage has an inlet
42 and an outlet 44. The passage, at the outlet, has a region 46 of minimum cross-section.
Proceeding in the length of the passage from the outlet to the inlet the cross-sectional
area of the core 14, and hence of the passage, increases monotonically.
Thus, at any location, the cross-section of the passage is greater than or equal to the
cross-section of the passage at an immediately preceding location. The core also has
no steps or discontinuities which could form undercut regions, and the passage is
therefore similarly formed. The cross-sectional area of the spigot 24, and hence of
the region 46, is substantially constant. The central section 22 is formed with a taper
of 2* and consequently the cross-sectional area of the central section increases
gradually moving from left to right in Figure 1.
The inlet 42 does not include a step or undercut formation which could prevent
retraction of the core. The core, as is evident particularly from Figure 2, has
outwardly extending V-shaped formations 48, at the section 26, which ultimately form
internal walls of a chamber of the pool cleaner. To the right of the section 26 the core
has a solid section 50 which is mainly provided for purposes of utility to enable the
core to be handled and correctly located inside the member 12.
As has been indicated plastic material, such as polypropylene 50 of a suitable grade,
is injected into the volume formed between opposing surfaces of the cavity 16 and the
core 14. The material sets around the core, the flotation component and the lead
weight. Once the material has set the body and the contained core 14 are removed
from the member 12. The core is then extracted from the body by withdrawing it
through the inlet 42. Although the core is closely surrounded by the material from
which the body is formed, and consequently there is an initial resistance to relative
movement between the core and the body, once the core has been moved to the right
relatively to the body (referring to Figure 1) the monotonic cross-sectional nature of
the core and, more particularly, the fact that the central section 22 is tapered, means
that only a small degree of relative movement between the body and the core is
necessary for the core to be moved freely away from the body.
As the core is withdrawn the spigots 34 are sheared. The spigots are, as has been
noted, anchored to the body and to the flotation component 18 and the lead weight
20. The spigots do not have substantial strength and the relative movement referred
to is sufficient to break the spigots so that the core can be withdrawn from the body.
The sections of the spigots which remain inside the body are simply left there.
Thus a method of constructing a pool cleaner body with an
embedded flotation component and bias component is provided.
Adjacent the inlet 42 the core and mould member 12 are shaped to define an
outwardly extending flange 52 which circumscribes a mouth 54 which is on, what in
use is, an upstream side of the pool cleaner body. The material of the body between
the inlet 42 and the mouth 54 is formed with two opposing holes 56, indicated in
dotted outline in Figure 1. The inlet has a surrounding shoulder 58.
The body has a length 60 and the flotation component 18 has a length 62, measured
in the general direction of the passage.
The length 62 is preferably in excess of 25% of the length 60 and more particularly
is at least 50% of the length 60. It has been found, totally fortuitously, that an
elongate flotation component of this type imparts considerable stability to the pool
cleaner body and also enables the pool cleaner body to take up the correct orientation
or attitude when it is immersed in water, particularly when it is first placed in the water.
Another surprising finding has been that the manoeuvrability of the cleaner, as
measured by its ability to rotate during movement, about its longitudinal axis, is
enhanced. This assists the cleaner in extricating itself from difficult positions within
a pool in which it is located and also increases the degree of random movement of the
pool cleaner.
The flotation component 18 is on an upper side of the pool cleaner body in use while
the lead weight 20 is on a lower side of the pool cleaner body, diametrically opposing
the flotation component. Thus buoyancy is exerted on the body by the flotation
component over a substantial portion of the length of the body while the biasing action
of the lead weight 20 is exerted at a localised position, towards a lower end of the
cleaner, which is on a lower side of the cleaner.
Although the body 10, formed in the manner described, is integral and has a unitary
construction it is not complete in the sense that it is not yet ready for use. Figure 3
is an end view of the cleaner illustrating only the inlet 42, which is of rectangular
cross-section, and the passage 40 which has a circular cross-section. Slots 64 are
formed on diametrically opposed sides of the passage by the two ribs 28 on the core.
Figure 4 is a cross-sectional view of the cavity 16 and core 14 taken on the line 4-4
in Figure 1.
Figure 6 is an end view of the cleaner and illustrates the flange 52 which surrounds
the mouth 54 and the inlet 42. Figure 6 also illustrates a closure or cover plate 70
which is separately moulded and which includes a centrally located hole or aperture
72. The body 10 has four relatively small inwardly extending flexible projections 74
surrounding the inlet 42. The cover plate 70 can be inserted through the mouth and
can be seated on the shoulder 58 by depressing the projections 74 to allow the cover
plate to pass the projections. The projections then revert to the illustrated positions
to keep the cover plate in position firmly fixed to the pool cleaner body. The cover
plate can easily be removed simply by inserting a finger through the hole 72 and
tugging on the cover plate. This is a highly useful feature for it enables dirt or debris
which may have been caught inside the passage to be accessed and removed. The
cover plate can then be re-engaged with the pool cleaner body.
Figure 5 shows a pre-formed partition 80 which includes an elongate section 82 of
rectangular dimensions and a V-shaped groove formation 84 at one end of the
section. A flow interrupting device which is in the form of a V-shaped hammer 88 has
a leading end 90 which is locatable in the groove formation 84. The hammer is
capable of moving to and fro as is indicated by means of an arrow 92, relatively to the
partition 80, between limiting positions which are defined by arms of the V-shaped
groove.
The partition 80 is designed to fit into the slots 64 in the inner wall of the passage 40.
This is done after the core has been removed from the body. The partition is slid into
the passage with opposing longitudinal edges being directly engaged in the
respective slots. The passage is thereby divided into first and second adjacent sub-passages
94 and 96 respectively. The V-shaped groove 84 is moved to a position
which is in register with the apices of the recessed formations which are formed by the
V-shaped formations 48. The hammer 88, which is shown in dotted outline in Figure
1, is thereby constrained in its movement between opposing internal inclined walls of
a chamber 98.
When the cover plate 70 is engaged with the body 10 the hammer is thereby held
captive inside the valve chamber.
The pool cleaner is used in a manner which is known in the art and which is therefore
not further described in detail herein. A skirt of any flexible material is engaged with
the outwardly projecting flange 52 and a suction hose is coupled to the outlet 44 using
a swivel connector of any appropriate type. When the pool cleaner is immersed in
water suction is applied to the suction hose and to the passage 40 by means of an
. external pump, not shown. The pump causes water to flow through the inlet 42 to the
outlet 44. The water flow causes the hammer 88 to oscillate to and fro inside the
valve chamber 98. The water flow alternatively surges through the two sub-passages
94 and 96 which are formed by the partition 80 which divides the main passage 40
into two D-shaped sub-passages with the partition forming a common wall between
the D-shaped sub-passages.
Figures 7 and 8 illustrate from the side and front respectively an important
modification which can be made to the pool cleaner.
The flat cover plate 70 of Figure 6 is replaced by a dome-shaped cover plate 70A
which has a centrally formed aperture 72A in a central surface of the cover plate
which is spaced from an opposing surface of the hammer 88 by a gap 91 which has
a width 93.
The width 93 is substantially equal to the maximum width 95 of a gap 97 which is
formed between opposing surfaces of the hammer and an inner wall of the chamber
98, in use of the pool cleaner. The modification does not affect the operation of the
hammer but it does improve the performance of the pool cleaner for the cleaner is
able to draw larger pieces of material, e.g. leaves, twigs, small stones etc, through the
hammer chamber and those pieces of material are far less likely to interfere with
hammer movement or become trapped inside the valve chamber. In any event, as has
been pointed out, the valve chamber is readily cleaned simply by removing the cover
plate to access the hammer and the valve chamber.
Another variation shown in Figures 7 and 8 is that the formation 84 of the partition 80
is dispensed with for opposed edges 99 of the hammer, at its apex, ride on formations
101 of a ledge 103 which internally surrounds the valve chamber.
It is to be noted that in Figure 8 the hammer 88 is shown in dotted outline.
The feature of manoeuvrability of the pool cleaner which is achieved through the use
of an extended flotation component, as has been described by referring to the
component 18 in Figure 1, can be achieved in another manner. For example,
referring to Figure 9, a plurality of separately formed and relatively smaller flotation
components 18A are embedded in a body 10A of a pool cleaner according to a
variation of the invention. The flotation components are of a size and number which
take into account the relative densities of the material of the pool cleaner body and
the density of the flotation components so that adequate buoyancy is imparted to the
body over its length. The components 18A may be of the same size or differ in size.
The important aspect in this regard is to provide buoyancy for the body over a
substantial portion of its length in order to achieve the benefits which have been
referred to hereinbefore. The remaining features of the pool cleaner body 10A are
substantially similar to corresponding features of the body 10 and hence have not
been elaborated on.
Figures 10 to 12 illustrate the principles of the invention applied to the construction
of a pool cleaner which makes use of a different type of flow interrupting device.
Figure 10 shows a pool cleaner body 100 which is moulded, substantially in the
manner which has described in connection with Figure 1, and which has a unitary one
piece body. The body includes an internal passage 102 which has a region 104 of
minimum cross-section. This region is close to an outlet 106 at one end of the body.
Between the region 104 and the outlet 106 the passage is flared and hence increases
monotonically moving to the right.
The passage at an opposing end has an inlet 108 and the cross-sectional area of the
passage moving from the region 104 to the inlet 108 increases monotonically. The
passage has a first section 110 with a first taper which gradually increases the cross-sectional
area of the passage and a second section 112 which is also tapered so that,
moving from right to left, the cross-sectional area of the section increases. A shoulder
114 is at a junction of the first and second sections.
The body has a mouth 116 which is surrounded by an outwardly extending flange 118.
A flexible skirt 120, of known construction, is engaged with the flange.
A biasing weight 122 is embedded in the body, using the technique which has been
described in connection with Figure 1. In the aforementioned respects the pool
cleaner body 100 is similar in concept to the pool cleaner body 10 shown in Figure 1.
The body 100 also includes a flotation component 124 which may be separately
formed and which is then embedded in the body during manufacture of the body.
However the applicant has discovered that the component 124 may be formed
integrally with the body by foaming the material from which the body is made. It has
been noted that the body is formed from a plastics material and this may be foamed
in a number of ways. The body may be foamed by the introduction of a foaming agent
which causes cavities or gas bubbles to be produced. This feature has been found
to manifest itself particularly in those regions of the body where the thickness of the
body is greater than a predetermined amount, for example of the order of 4mm.
Consequently by keeping this aspect in mind it is possible, through judicious design,
to ensure that the plastics material, which is injected into the moulds used for making
the body, is caused to solidify substantially without any foaming action taking place
over those portions of the body which define walls which are relatively thin bounding
the flow passage 102. By increasing the dimensions of the body relatively to the flow
passage a larger volume is formed in which foaming action takes place and, in this
way, the component 124 can be formed integrally with the material of the body. The
foaming action may be initiated in various ways which are known in the plastics
industry. For example use may be made of a cellular plastics material with the cellular
construction being produced by the effect of a gas which is injected into the plastics
material before it has set or which is generated during the injection process by means
of chemical action. Thus, by manipulating the characteristics of the moulding process,
it is possible to form the body with sections that are less dense than the remaining
sections of the body and each such less dense section is, in effect, a flotation
element. On the other hand with gas injection techniques of plastics material it is
known that the plastic material, when it comes into contact with a mould surface,
particularly a heated mould surface, forms a section which is relatively free of gas.
By manipulating the characteristics of the mould it is possible to ensure that a
substantial portion of the body is formed with a substantial amount of cells which
impart to such portion a less dense characteristic. An opposing side of the pool
cleaner body which carries the lead weight 122 is made more dense and hence is not
foamed.
The body has a removable bumper strip 126 which is made from a material such as
polyurethane which is abrasion and wear-resistant. The inset drawing to Figure 10
shows the cross-section of the strip. The bumper strip has an elongate rib 128 with
a bulbous end 130 which is engageable with a press fit into a slot 132 of
corresponding dimensions formed in a lower longitudinal edge of the body.
Figure 11 illustrates a flow interrupting mechanism 136 which is of known construction
and which includes a tube 138 and a diaphragm valve 140. As shown in Figure 12
the device 136 is insertable into the passage 102 through the inlet 108. The
diaphragm 140 seats on a shoulder 142 and a remote end 144 of the tube which is
formed with gripping formations 146 is then engaged with a compression ring 148
which is encompassed by a union nut 150 which is threadedly engaged with a
threaded boss 152 of the body around the outlet 106. A swivel connector 154 extends
from the nut and is connectable to a suction hose, not shown.
When suction is applied to the connector 154 water flow through the diaphragm valve
140 causes the valve to open and close, in a manner which is known in the art, and
the pulsating action of the water flow causes the pool cleaner to move in a random
manner over a surface which is to be cleaned.
The pool cleaner shown in Figure 12 possesses similar advantages to what have
been described in connection with the other embodiments, namely the length 160 of
the elongate flotation component is considerably in excess of 25% of the length 162
of the pool cleaner body, between the inlet and the outlet, and the pool cleaner thus
possesses considerable manouverability during use. A second factor is that the body
is of a unitary construction.
The foamed flotation component is particularly useful for it eliminates a separate
moulding step. Another important benefit is that by using substantially dense plastics
material, and by careful control of the volumes in which foaming takes place, or does
not take place the volume which is occupied by the weight 122 can be formed with
solid plastics material, which provides the required bias, and the weight can be
eliminated. It may however be necessary to enlarge the solid plastics section to
obtain a mass which is equivalent to the mass of the lead weight which is replaced by
the plastics section.
The minimum cross-sectional area of the passage, in the body of the cleaner, is
preferably at one end of the passage for this requires a single core. If the region of
minimum cross-sectional area is at an intermediate position in the passage then the
monotonic increase in cross-sectional area is in two directions, each towards a
respective end of the passage, and two cores are required, each inserted into the
mould member 12 from a different side and in opposing directions.