Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Specification
Evaporation Control Adaptor Sleeve for Vaporizer Electrode
Field of the Invention
This invention relates to domestic vaporizers in which electric
current flows through water between two electrodes and generates
steam in order to raise the humidity of the surrounding air.
Background of the Invention
Vaporizers are used in numerous households in the country. They
are inexpensive and reliable. However, as the hardness of the
water varies from one locality to the next, so does its
conductivity and the rate of vaporization. If the water is too
hard, the electric current is too high, and the vaporizer
malfunctions. The symptoms of this malfunction include premature
depletion of the water reservoir, and spraying of hot liquid
water from the steam outlet. The remedy currently recommended by
manufacturers is dilution of the local tap water with distilled
water, which reduces the conductivity. This solution is
inconvenient and expensive.
The above problem has been known for a long time and several
patents have been granted for solutions. Many patents propose to
increase the current path between the electrodes of the vaporizer
in order to increase the total resistance between them and thus
to reduce the vaporization rate. In US patents #3,308,267 to
Fenstermaker, and #4,205,222 to Williams, and also in Canadian
patent 1,166,296 to Howard-Leicester, it is suggested that the
current path be lengthened by interposing plastic insulating
components between the electrodes. In the most sophisticated of
these three patents, Williams proposes to equip his boiler with a
movable insulating sleeve 17, interposed between electrode 8 and
counter-electrode 10, in order to vary the current path, as shown
in Fig. 1 of the patent.
No doubt, each of the proposed solutions will work in the
environment for which the device is designed, but none of them
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responds to the needs of a typical household user. The Williams
apparatus, for instance, is much too complicated and expensive.
The Fenstermaker vaporizer is simple and inexpensive, but it can
not easily be adjusted to the needs of the individual user. His
insulating strip 23, which lengthens the current path between
electrodes 20 and 21, is permanently fixed to electrode 21 at the
factory.
Brief Summary of the Invention
This invention solves the problem of the prior art vaporizer,
outlined above, by providing a simple and inexpensive adaptor for
reducing and limiting the current through the vaporizer to a
desired value. In all embodiments of the invention, the adaptor
takes the form of a tubular or sleeve-like insulating member
placed to surround at least one of the electrodes such that it
will restrict and control the direction and magnitude of the
current flowing between the electrodes.
In the several disclosed embodiments, the insulating members
differ in shape and have different mechanical and structural
features. The adapter may be a semi-rigid tube or a flexible
elastic sleeve placed on at least one electrode, or it may be an
insulating cylinder having numerous perforations distributed over
its wall to permit controlled current flow through the
perforations in the wall to and from the electrode inside the
cylinder. A most important aspect of the present invention is the
fact that it provides an adaptor which can easily be installed by
the user of the appliance, exchanged or adapted in size, if
necessary, to obtain a particular desired level of evaporation,
having regard to the hardness of the available water supply. The
proposed invention will work only if the available water supply
is too hard, resulting in excessive current and evaporation. If,
on the contrary, the water is too soft, the present invention is
not applicable.
Brief description of the Drawings
FIGURE 1 is a schematic elevational view, partly in section, of
a common household vaporizer,
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FIGURE 2 is a vertical sectional view of the vaporizer chamber
of the first and preferred embodiment along line 2-2 of Figure 3
with the novel adaptor installed on one of the electrodes,
FIGURE 3 is a horizontal sectional view taken along line 3---3
of the Fig.2,
FIGURE 4 illustrates a vertical sectional view of another
embodiment.
FIGURE 5 is a horizontal cross-sectional view along line 5---5
of Fig. 4
FIGURE 6 is a vertical sectional view of a third embodiment of
the invention, and
FIGURE 7 is a horizontal cross-sectional view along line 7---7
of Fig. 6 illustrating means for supporting the adaptor relative
to an electrode.
Detailed Description of the Invention
Fig. 1 illustrates a conventional household vaporizer which
consists of a reservoir 11, containing a vaporizable liquid 12,
the level 13 of which will drop due to evaporation. The
vaporization takes place in the vaporization chamber 14 which is
supported by its cap 15 on the neck 16 at the top of the
reservoir. The cap and vaporization chamber are fastened together
by means of screws. Within the vaporization chamber, two
electrodes 17 and 18 are suspended from cap 15, where they are
connected to respective electric terminals 19 and 20, which in
turn may be connected to a household current supply in a well
known manner. The chamber 14 has at the bottom a liquid inlet 21
and at the top a steam outlet 1. Because of the inlet 21, the
liquid level within the chamber 14 is the same as outside in the
reservoir 11. The liquid 12 is usually tap water, but it could
contain medicinal or other additives. Thus the term "liquid"
encompasses tap water as well as any other suitable aqueous
solutions. When current is passed between electrodes, the heat
generated in the vaporizer chamber generates steam which exits
through outlet 1.
The electrodes may be flat or slightly curved to improve their
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rigidity, as is known in the prior art, and illustrated at 17 in
Fig. 3.
Figures 2 and 3 illustrate the first and preferred embodiment
of the invention. The novel adaptor 22 is placed on electrode 18,
within the vaporizer chamber 14. The adaptor is a piece of a
fairly thin semirigid insulating tube. Its diameter is chosen to
be slightly smaller than the width of the essentially flat metal
electrode 18, so that the tube must be deformed slightly, as
shown in Fig. 3, to be fitted over the electrode. The compression
produced by this deformation causes the tubing to remain in place
on the electrode.
Without the adaptor 22, the current path between the electrodes
17 and 18 would be very short and very wide, resulting in maximum
current flow. Due to the adaptor, however, most of the current to
and from electrode 18 must travel a much longer and narrower path
up and down inside the adaptor, as shown at 27, before it reaches
the bottom end 24 of the tube 22, from where it can proceed
across to the other electrode. Thus, depending on the dimensions
of the adaptor, it can reduce the total current flow quite
substantially.
If it is desired to increase the current, the adaptor may be
shortened by cutting it at line 25, for instance. This will
decrease the effective length of the path and its resistance.
Conversely, the lengthening of the adaptor by adding a piece of
tubing or by replacing it with a longer tube will reduce the
current and the vaporization rate. The adaptor may be assembled
of several coaxial sections of tubing of different lengths to
obtain the desired result.
The unique advantage of the present invention is therefore that
it offers every user a very simple means to adapt the operation
of his vaporizer to his personal needs and to the hardness of his
water supply. He may do that by trial and error. He may keep on
hand several different lengths of the tubing, or one longer piece
of tubing to be cut into shorter pieces, as required. The local
vendor selling the appliance may suggest what length may be the
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most suitable.
In Fig. 2, the top end 23 of the adaptor is shown to protrude
above the surface of the liquid, which is the preferred
arrangement. The vaporizer will also function if the top end of
the adaptor is submerged below the liquid surface, as at 26, but
then, when the liquid level drops below line 26, the top branch
of the current path will be cut off. This may produce an
undesirable abrupt change in the rate of current flow and
evaporation. No such abrupt change will occur if the current
flows always only through the bottom of the adaptor, as in Fig.
2.
Fig. 3, being a cross-sectional view of Fig 2, shows that the
shape of the normally round tube is slightly deformed to an oval
shape to be placed on the electrode and is held thereon by
slightly pressing inward against the edges of the electrode.
In Fig 4 and Fig 5, the adaptor takes the form of a thin soft
elastic sleeve 28, which must be stretched somewhat to be slipped
onto the electrode 18. Since the sleeve 28 is in full contact
with the electrode 18, there is no free space and no current flow
between the two, as there was in the preceding embodiment.
However, by covering a certain upper portion of the electrode by
sleeve 28, this portion is excluded from current conduction, so
that current can flow only to and from the uncovered or bare
lower portion 29 of the electrode 18. By varying the size and
arrangement of sleeve 28, the dimension of the lower bare portion
can be varied as desired. If the bare portion 29 of the electrode
were very small or nil, i.e. if the sleeve would cover the
electrode 18 completely to its bottom end 30, then the total
current conducted would be also very small or almost nil. On the
other hand, if at least a substantial lower part of the electrode
is bare, then the total current will be somewhere between nil and
a maximum. Thus, by trial and error, the user may adjust his
adaptor to obtain the desired evaporation rate.
To increase evaporation, he may increase the bare portion by
cutting a piece off the lower end of the sleeve. Alternatively,
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instead of cutting, the lower end of the elastic sleeve may be
turned over on itself and pulled up, as shown at 31 in Fig 4.
Conversely, this end may be lowered to decrease the bare portion.
In this embodiment, again, the upper end of sleeve 28 protrudes
above the surface of the liquid.
In Fig. 6, illustrating the third embodiment of the invention,
the adaptor consists again of a rigid or semi-rigid insulating
tubular member 32, which is surrounding the electrode 18 within
the vaporization chamber 14. In this tubular member, however, the
wall is perforated as shown at 33. These perforations will reduce
the current flow depending on their size and number. They may be
distributed evenly over the whole surface of the member 32, or be
limited to a portion or a side of the member, either to the side
facing the opposite electrode 17, or to any other side. The
perforations may be larger or more numerous on some portion of
the tube than on some other portion at a different height along
the tube; this will cause the rate of evaporation to change with
time in a different manner than if the perforations were uniform
over the tube. For example, it may be desirable to begin with a
high rate of evaporation to elevate the room humidity quickly,
and then to continue at a lower rate of evaporation sufficient to
maintain the room humidity. This can be accomplished with a tube
having larger, and/or more (as shown in Figure 6), perforations
per unit surface area near the top of the tube than near the
bottom. To restrict the current to the perforations only (as
shown at 27), the top of the tube 32 again protrudes above the
liquid surface 13, while its lower end is closed by an integral
bottom 34 as shown in Fig. 6. On the other hand, this integral
bottom may be omitted if the lower edge of tube 32 is straight
and fits closely on the flat bottom of vaporization chamber 14.
In this embodiment, the perforated member 32 could be
free-standing. If its inner diameter is not much larger than the
width of the electrode 18, then it cannot move very much
laterally with respect to the electrode. Preferably, however, it
is supported immovably with respect to the electrode to stabilize
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the current path.
In Fig. 6 numerals 35 and 36 indicate two identical rigid
supports or spacers centering electrode 18 within adaptor 32 and
holding the two substantially immovably with respect to each
other. As can be seen from Fig. 7, support or spacer 35 is a
narrow, flat strip of insulating material, extending between
opposite inside walls of adaptor 32 and having at its center an
elongated slot 37 to accommodate the electrode 18. Spacer 35 may
be firmly attached to the wall of the adaptor, such as by gluing,
in which case it will not be attached to the electrode but have a
small clearance between slot 37 and the electrode for easy
insertion or removal of the latter. On the other hand, the spacer
35 may be firmly attached to the electrode, such as by friction
or some simple snap-on arrangement, in which case the spacer will
not be attached to the adaptor wall, but due to a small clearance
therebetween, will slide easily parallel to the wall when the
electrode - spacer combination is inserted or removed from the
adaptor.
The construction of the lower spacer 36 is identical to, and
aligned with, spacer 35. More than two spacers could be used, but
for most applications two should be enough. Care must be taken
that the width of spacers 35 and 36 is not too large, so as not
to obstruct unduly the upward movement of the steam generated
within the adaptor 32.
Another possibility is to manufacture the perforated tubular
member 32 without the bottom 34, but from a semirigid material
as in the embodiment of Figs 2 and 3. Again, its diameter will be
slightly smaller than the width of the respective electrode, so
that the tube must be compressed laterally to fit it over the
electrode. Again, when the compression is removed, the tube will
engage the electrode, as seen in Fig.3. In this case the supports
35 and 36 shown in Figs 6 and 7 are not required. Of course, even
with an integral bottom 34, the tube could be made flexible
enough to be compressed sufficiently to be slipped onto electrode
18. In this third embodiment, the user can not very well himself
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change the dimensions of the adaptor as it was possible in the
previous two embodiments, but he may still adjust the current by
installing a tube with larger (or more) or smaller (or fewer)
perforations. The vendor, again, may recommend a particular tube
suitable for most users with the available water supply.
In all embodiments, the material used for the insulating sleeve
must be heat-resistant. Mylar, of the solid, moldable variety,
or Teflon, could be used for the semi-rigid sleeve. For the
elastic sleeve, an elastomer should be used, such as Neoprene, or
any of the heat-resistant silicone rubbers.
For clarity's sake, in all of the above embodiments the
invention is illustrated by using the simplest structure, i.e.
the vaporizer has only two electrodes, an adaptor is placed on
only one electrode, and the adaptor consists of only one piece of
tubing. However, just as possible and feasible would be more
complex structures, having more than two electrodes, having an
adaptor on more than one electrode, or having an adaptor composed
of more than one piece of tubing. Combinations of features are
also possible, e.g. the adaptor of the second embodiment could be
provided also with perforations of the type shown in Fig. 6.
Evidently, other obvious alternatives will be apparent to those
skilled in the art. Accordingly, it is intended to embrace all
such alternatives as fall within the spirit of the invention and
broad scope of the appended claims.
Also, for clarity's sake, in the disclosure and claims, the
term 'Ito adjust the adaptor sleeve" means a one-time or
occasional adjustment of its length while the vaporizer is not
operating, as clearly distinct from any continual variation
during the operation of the device.
Similarly, the term "elastic" as applied to the sleeve means
that its material is an elastomer and therefore easily
stretchable and thereafter will tend to resume its former shape,
as opposed to an only flexible, but not stretchable material.
