Note: Descriptions are shown in the official language in which they were submitted.
22 ~ ~ 2 ~ ~
COLD THERAPY DEVICE
FIELD OF THE INVENTION
The present invention relates to devices for cold and/or hot therapy
and devices for cooling and/or heating adjacent areas on a person for
therapeutic purposes.
BACKGROUND OF THE INVENTION
Pain abatement research is a major area of study which goes
hand-in-hand with pain research itself. In many cases pain is a symptom of an
underlying malady or trauma so the presence and nature of the pain in these
cases is sometimes essential in aiding awareness and the diagnosis of the
underlying illness. The abatement of pain has traditionally been effected
using
various external and internal treatments. Examples of external treatment
include
acupuncture, electro-shock treatment using transcutaneous electrical nerve
stimulation (TENS), use of temperature such as application of hot or cold
packs
or topical application of cooling or heating formulations. Examples of
internal,
invasive treatments include drug treatments by oral administration or
injection
of freezing agents. Where feasible, the external physical methods of
alleviating
pain are preferable over the invasive, internal techniques for obvious
reasons.
The application of hot or cold to localized pain such as muscle or
tendon pain to reduce swelling has a long history. There are many devices for
heating or cooling parts of the body. Hot water bottles and ice or cold packs
are
among the oldest and simplest devices for applying heat and cooling
respectively. Another type of device is the heating blanket that uses
electrical
resistive heaters for heating. United States Patent No. 4,094,357 discloses a
heat transfer blanket which uses heat pipes coupled to heating/cooling
systems.
United States Patent No. 5,269,369 teaches a body suit which utilizes a system
of heat pipes to redistribute body heat for heating or cooling the person
wearing
the suit.
United States Patent Nos. 4,459,468 issued to Bailey discloses a
temperature control fluid circulating system provided with a thermal blanket
and
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.,
a large refrigerant reservoir using thermoelectric units inserted directly
into the
reservoir to heat and cool the refrigerant in the reservoir. United States
Patent
No. 3,154,926 issued to Hirschhorn teaches a cooling blanket with a coolant
reservoir with substantially all of one side of the reservoir in contact with
thermoelectric Pettier units to cool the liquid in the reservoir. United
States
Patent No. 4,523,594 issued to Kuznetz discloses a heat exchange jacket that
can be used in an open loop mode or a closed loop mode. In the open loop
mode the jacket is connected to a hot or cold water faucet in a hospital or
home
while in the closed loop mode a thermoelectric device is used to heatlcool
water
in the reservoir which is in series with a pump. Similarly, United States
Patent
No. 3,967,627 issued to Brown is directed to a hot/cold applicator system
utilizing a peristaltic pump in series with a patient blanket, a fluid
reservoir and
a heat exchanger for heating/cooling the fluid. A drawback to these types of
devices is poor efficiency of cooling the refrigerant since essentially the
entire
volume of coolant contained in the reservoir must be cooled.
United States Patent Nos. 4,962,761 to Golden and 5,174,285 to
Fontenot disclose fluid circulation systems for use with thermal bandages,
pads
or blankets. These devices provide a thermal blanket with closed loop fluid
circulation systems with fluid module housings which are in thermal contact
with
heating/cooling devices. A drawback to these types of devices is poor cooling
efficiency for cooling the refrigerant since the latter contacts the cooling
devices
indirectly through the walls of the fluid modules.
United States Patent No. 3,888,259 issued to Miley discloses
hypothermia device for therapeutic applications. The device includes a fluid
pump located between a heat exchanger and a reservoir and a double impeller
pump with an upper impeller connected in series with the reservoir and the hot
side of a thermoelectric unit and a lower impeller pump connected in series
with
the cold side of the thermoelectric unit and the patient blanket. Once water
fills
the system during operation of the pumps a quasi closed-loop is set up for the
cooling water circulated between the blanket, the second set of impellers and
the cooled side of the thermoelectric unit. A drawback to this system is the
need
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for two pumps to sustain the pumping action in the two circulation systems.
United States Patent No. 4,170, 998 to Sauder is directed to a
portable cooling apparatus for cooling a limb of a patient which includes a
compressor and evaporator for condensing and evaporating the refrigerant. A
drawback to this type of system and others like it is that they are quite
bulky and
awkward since they use large fluid pumps between the heat exchanger and the
blanket or pad being heated or cooled. Some of the systems employ
condensers, refrigerants and evaporator coils which are also bulky, awkward
and of limited mobility.
It would therefore be advantageous to provide compact and
economical devices for thermal treatment of maladies or trauma of the body
provided with an efficient method of rapidly cooling/heating the refrigerant.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a compact and
portable heat exchange device for heat exchange therapy of patients.
In one aspect the present invention provides a portable heat
exchange device for heat exchange therapy of a patient. The device comprises
a heat exchange pad means having at least one fluid inlet and one fluid outlet
through which a fluid exchange medium may be circulated through the pad
means. The device includes a heat exchange module including a first housing
having a fluid recirculation inlet and a fluid recirculation outlet and
conduit
means communicating the recirculating fluid inlet and the recirculating fluid
with
the fluid outlet and fluid inlet, respectively, of the pad means. A first
chamber is
located within the first housing in fluid communication with a source of fluid
heat
exchange medium and the fluid recirculation inlet and fluid recirculation
outlet.
The first housing has at least one opening into the first chamber, and one of
either a heat source and a heat sink having an inner surface is mounted within
the opening with the inner surface in heat exchange relationship with the
fluid
heat exchange medium within the first chamber. The device includes means for
circulating the fluid heat exchange medium through the first chamber so as to
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contact the inner surface and to convey the fluid heat exchange medium to the
recirculating fluid outlet to the pad means.
In a preferred embodiment, the one of either a heat source and
heat sink is a thermoelectric Pettier unit comprising the inner surface and
having
an opposed outer surtace.
In another aspect of the invention there is provided a portable
therapeutic heat exchange device comprising heat exchange pad means having
at least one fluid inlet and one fluid outlet through which a fluid heat
exchange
medium may be circulated through the pad means. The heat exchange device
includes a heat exchange module including a housing provided with a fluid
recirculation inlet and a fluid recirculation outlet and conduit means
communicating the recirculating fluid inlet and the recirculating fluid outlet
with
the fluid outlet and fluid inlet respectively, of the heat exchange pad means.
The
housing includes a chamber in flow communication with a source of fluid heat
exchange medium and the fluid recirculation inlet and the fluid recirculation
outlet. The housing includes at least one opening that opens into the chamber
and a thermoelectric Pettier unit having a heated outer surface and a cooled
inner surtace is mounted within the opening with the inner surtace in heat
exchange relationship with the fluid heat exchange medium within the chamber.
The device includes means for circulating the fluid heat exchange medium
through the chamber so as to contact the cooled inner surface and to convey
the
fluid heat exchange medium to the recirculating fluid outlet to the pad means.
The device includes a heat exchanger with a heat exchanger chamber, a
thermally conducting solid portion adjacent to the chamber and a finned
portion
extending from the solid portion. The cooling module is seated in the heat
exchanger chamber with the outer heated surface thermally contacted to the
solid portion.
In another aspect of the invention there is provided a compact heat
exchange device for cooling and/or heating a heat exchange fluid. The device
comprises a heat exchange module including a first housing having a fluid
._
recirculation inlet and a fluid recirculation outlet, a first chamber within
the first
housing in fluid communication with the fluid recirculation inlet and the
fluid
recirculation outlet. The first housing is provided with at least one opening
in the
into the first chamber and a thermoelectric Pettier unit having a first
surface and
an opposed second surtace is mounted within the at least one opening and is
in liquid tight sealing relationship with the housing with the first surface
in heat
exchange relationship with a fluid heat exchange medium within the first
chamber. The device includes a first pump with a first impeller, the first
pump
being attached to the first housing in communication with the fluid
recirculation
outlet to pump for circulating the heat exchange fluid through the first
chamber
so as to contact the first surface and to convey the heat exchange fluid
through
the recirculating fluid outlet.
The present invention also provides heat exchanger comprising
a thermally conducting solid portion having a heat exchanger chamber with at
least one surtace adapted to receive thereagainst and object to be cooled. The
heat exchanger includes a thermally conducting finned portion in thermal
contact
with the thermally conducting solid portion. In a preferred embodiment of the
heat exchanger, the heat exchanger comprises a plurality of heat exchange
plates assembled in a stacked relationship wherein each heat exchanger plate
has a central section and at least one fin portion extending from the central
section. The central section of each heat exchanger plate has an aperture and
the central sections of adjacent heat exchange plates are partially overlapped
to form the thermally conducting solid portion with the apertures in
registration
to define walls of the heat exchanger chamber. The fin portions of adjacent
plates in the stack are spaced by dimples located on each fin portion of the
plate.
BRIEF DESCRIPTION OF THE DRAV111NGS
The following is a description, by way of example only, of heat
exchange therapy devices constructed in accordance with the present invention,
reference being had to the accompanying drawings, in which:
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Figure 1 is a perspective view of an apparatus for heating and
cooling constructed in accordance with the present invention;
Figure 2 is a cross sectional view along line 2-2 of Figure 1;
Figure 3a is a top view of a heat exchanger forming part of the
apparatus in Figure 1;
Figure 3b is a sectional view along the line 3b-3b of Figure 3a;
Figure 3c is an enlarged view of the circled portion of Figure 3b;
Figure 4 is a top view of the structural member from which the heat
exchanger of Figure 3a is constructed;
Figure 5 is an assembly view of a cooling module forming part of
the present invention;
Figure 6a is a sectional view along line 6a-6a of Figure 5;
Figure 6b is a sectional view along line 6b-6b of Figure 5;
Figure 7a is an exploded perspective view of the apparatus of
Figure 1;
Figure 7b is a perspective view of the cold therapy device of Figure
1 partially assembled;
Figure 8a is a sectional view along line 8a-8a of Figure 8b;
Figure 8b is a top view of the water reservoir of Figure 7a;
Figure 8c is an enlarged sectional view of the circled portion of
Figure 8a;
Figure 9 is a sectional view along the line 9-9 of Figure 7b;
Figure 10 is a diagrammatic illustration of the cold therapy device
of Figure 1;
Figure 11 is a flow diagram of the operating logic employed in the
control circuit forming part of the cooling apparatus;
Figure 12a is a perspective view of an alternative embodiment of
a cooling chamber according to the present invention;
Figure 12b is an elevational view of the cooling chamber of Figure
12a;
Figure 12c is a bottom view of the cooling chamber of Figure 12a;
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Figure 13a is a bottom view of an alternative embodiment of a
cooling unit according to the present invention;
Figure 13b is a perspective view of the cooling unit of Figure 13a
and associated heat exchanger, having a portion removed;
Figure 14 is a bottom view of an alternative embodiment of a
cooling unit according to the present invention;
Figure 15 is a perspective view of an alternative embodiment of a
heat exchanger of the present cooling device;
Figure 16 is a perspective view of another embodiment of a heat
exchanger of the present cooling device;
Figure 17 is a perspective view of another alternative embodiment
of a heat exchanger of the present cooling device;
Figure 18 is a top view of another alternative embodiment of a heat
exchanger of the present cooling device;
Figure 19 is a cross sectional view along the line 19-19 of Figure
18;
Figure 20 is a cross sectional view along the line 20-20 of Figure
18;
Figure 21 is a sectional view, broken away, showing several plates
in Figure 19 stacked to form a cooling chamber;
Figure 22 is a perspective view of an alternative embodiment of an
apparatus for heating and cooling constructed in accordance with the present
invention;
Figure 23 a sectional view of a water pump forming part of the
apparatus of Figure 22;
Figure 24 is an exploded view of a portion of the fluid pump of
Figure 22;
Figure 25 is an assembly view of an alternative embodiment of a
heating/cooling module constructed in accordance with the present invention;
Figure 26a is a cross sectional view taken along line 26a-26a in
Figure 25;
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Figure 26b is an exploded view of the section of Figure 26a;
Figure 26c is similar to Figure 26b showing the fluid flow path;
Figure 27 shows the assembled cooling module of Figures 25;
Figure 28 is a perspective view of a the cooling module of Figure
25 disassembled; and
Figure 29 is a perspective view of part of the cooling module of
Figure 26.
DETAILED DESCRIPTION OF THE INVENTION
Figures 1 and 2 show a cooling apparatus 20 constructed in
accordance with the present invention. Cooling apparatus 20 includes a heat
exchanger 22 with a base plate 24 and four grommets 26 attached to base plate
24 to provide a support for the device. A housing 28 is mounted on top of heat
exchanger 22 and is provided with a carrying handle 30 for carrying the
assembled apparatus. Housing 28 includes a pair of spaced hooks 32, best
seen in Figure 1, disposed along one side of housing 28 for hooking the
apparatus 20 onto a bed railing or wall rail beside a patient using the
device. An
on-off switch 38 and a cord 40 provide power to the apparatus.
Referring specifically to Figure 2, housing 28 encloses two power
supplies 44 and a control circuit 46 mounted on top of the power supplies.
Housing 28 encloses a reservoir 34 having a pop-top lid 36 for filling the
reservoir. Heat exchanger 22 contains two cooling fans 50 one located on each
side of a cooling chamber 52. Cooling module 56 is received into cooling
chamber 52.
Referring to Figures 3a to 3c and Figure 4, heat exchanger 22 is
constructed by overlapping alternating heat conducting plates 58, preferably
aluminum, where all the elements are structurally identical. Four bolts 60 are
used to secure the stack of elements 58 together. Referring to Figure 4, each
heat conducting element 58 is has a triangular middle section 62 having a base
64 and elongate L-shaped frame members 68 extending from base 64. The
middle section 62 encloses a rectangular aperture 66. Element 58 includes
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holes 70 at both ends of arms 68 in addition to holes 72 in the middle portion
62
through Which bolts 60 are inserted to secure the assembled heat exchanger
together. The end portions 68 are provided with dimples 74 extending upwardly
out of the plane of plate 58 and dimples 76 extending downwardly in the
opposite direction. A tab 78 extends outwardly from arm 68 and is provided
with
a notch 80. One of the triangular sections 62 is provided with a triangular
protrusion having a notched apex 84.
The stack of plates 58 is assembled as shown in Figure 3b so the
dimples 74 and 76 line up as seen in the enlargement of Figure 3c. The
chamber 52 (Figure 3a) thereby formed is originally rectangular because all
the
apertures 66 (Figure 4) are the same size. The tapered chamber 52 in Figure 3b
is obtained by machining out the heat exchanger chamber so that the upper
portion 88 of the chamber 52 is wider and tapers to the lower portion 90. The
inner walls of 96 and 98 of tapered chamber 52 are essentially solid since the
plates 58 are tightly compressed together before machining. The triangular
portions 94 formed by the overlapping sections 62 of each plate 58 in the
assembled heat exchanger form a thermally conducting solid portion and the
elongate frame members 68 extending out from the solid portion form the finned
portion of the exchanger with a gap between adjacent plates in the finned
section due to dimples 74 and 76 acting as spacers.
Referring to Figure 3a, when heat exchanger 22 is assembled from
plates 58, notches 84 and 80 on each side of chamber 52 define a rectangular
volume. The cooling fans 50 (Figure 2) fit into these rectangular volumes. The
solid triangular portions 94 provide excellent heat conduction away from walls
98 into the finned portion of the heat exchanger. The heat flow from chamber
wall 98 into the finned portion of the heat exchanger is parallel to the
surtace of
the plates thereby advantageously providing optimum heat transfer from wall 98
to the surface area for heat dissipation. The size of the solid portion of the
heat
exchanger is preferably kept to a minimum as it is required to conduct heat
from
the thermal contact surfaces to the finned portions.
Details of cooling module 56 are shown in Figures 5, 6a and 6b.
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Cooling module 56 comprises a housing 110 that is tapered, best seen in Figure
6a. The taper of housing 110 substantially matches the angle of the taper of
chamber 52 in heat exchanger 22, see Figure 3b. Housing 110 encloses a
chamber 112 with opposed open sides with an O-ring groove 114 extending
around the opening on each face. As shown in Figures 5 and 6b, housing 110
includes passageways 116 and 118 into which spigots 120 and 122 respectively
are inserted. Alternatively, spigots 120 and 122 may be formed with housing
110
as a unitary structure as shown in Figure 6b. Referring specifically to Figure
6b,
passageway 118 is the fluid flow path back into chamber 112 from the cooled
blanket and includes an upper wider channel 124 and a narrower lower channel
126 in flow communication with chamber 112. A channel 130 extends through
housing 110 to communicate with upper channel portion 124 and a channel 128
extends through the housing to communicate with lower channel portion 126,
best seen in Figure 6a.
Cooling module 56 is provided with a liquid pressure/flow sensor
132 having spaced conduits 134 and 136 inserted into passageways 128 and
130 respectively. Pressure/flow sensor 132 is placed in the flow circuit with
the
restriction between passageways 124 and 126 located between its inputs. The
restriction creates a pressure difference across sensor 132 which indicates
flow
and no flow conditions. Silicon pressure sensors, model numbers MPX10,
MPX11 and MPX12 produced by Motorola have been found to be quite
adequate.
Housing 110 is provided with a channel 142 in flow communication
with chamber 112. A fitting 144 protruding from housing 110 is in flow
communication with passageway 116 and is used for filling chamber 112 when
the cooling module is assembled. Passageway 116 provides an air return line
from chamber 112 to reservoir 34 so that air is displaced from chamber 112
into
reservoir 34 as the chamber is being filled.
Referring to Figures 5 and 6a, the openings in the two opposing
faces of housing 110 are rectangular and are adapted to receive thermoelectric
units 148 With the edges of the units sealing against the O-ring 158 seated in
O
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ring groove 114 to form a tight seal. Each thermoelectric unit 148 includes
opposed surfaces 150 and 152 and a pair of wires 154 which are electrically
connected to the control circuit 46 (Figure 7a). A pair of groves 138 and 140
extend upwardly from O-ring groove 114 and provide a channel for each of the
electrical wires 154. A liquid pump 160 is coupled to housing 110 with an O-
ring
seal 161 and spring bracket 170 and the pump comprises a impeller shaft
housing 162 in which an impeller 164 is housed. The impeller housing 162 is
inserted into passageway 142 and the pump is secured to the housing by means
of the spring bracket 170 which is pivotally attached to the housing 110 and
snaps over the upper end 168 of the pump. When pump motor 160 is coupled
to housing 110 a portion of the impeller housing 162 and impeller 164 are
located in chamber 112 adjacent to the inner cooled surface 150 of
thermoelectric module 148 to ensure a vigorous flow of fluid against the
module
surfaces. Electrical connection is made to pump 160 through the plug 176
protruding from end portion 168. Pump 160 is provided with a liquid outlet 166
for circulating the cooled liquid out of chamber 112.
Referring to Figures 8a, 8b and 9, water reservoir 34 is preferably
moulded of a translucent plastic to allow viewing of the water or liquid level
in
the reservoir but which does not become unsightly as would a clear plastic
after
prolonged exposure to tap water. Reservoir 34 has an opening 180 for filling
with water or other heat exchange fluid. An air return line connection 182 is
located at the top of the reservoir and an air line 196 is attached thereto at
one
end. The reservoir 34 is provided with a downwardly extending section 184
spaced away from the outer wall containing the air return line connection 182
thereby defining a gap 194. The air return line is protected from the
reservoir
being overfilled by an air pocket forming in gap 194 thus preventing water
from
filling the air return. A filler spigot 188 is located on the bottom 190 of
the
reservoir and a filter 192 covers the outlet passageway, best seen in Figure
9.
A filler tube 198 is attached to spigot 188 at one end thereof. Reservoir lid
36 is
provided with several small holes 39 (Figure 7a) which are small enough to
resist water flow due to surface tension but large enough to allow easy
passage
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of air. Lid holes 39 advantageously permit the chamber 112 to be filled with
fluid
from reservoir 34 without creating a vacuum. The volume of fluid into chamber
112 is replaced with a volume of air through holes 39.
With reference to Figure 7b, tube 198 is attached to spigot 144
(Figure 5) located on the housing of cooling module 56 to provide a cooling
liquid supply to the cooling unit from reservoir 34. The other end of air line
196
is connected to air return spigot 120. Hose 172 is connected to spigot 122 and
provides the liquid return line from the cooling blanket. Hose 174 is
connected
at one end to fitting 166 on pump 160 and the other end is connected to the
cooling blanket thereby supplying liquid to the blanket 200 (Figure 10).
In operation, heat is extracted out of the fluid in chamber 112 by
the two thermoelectric units 148 (Figures 6a and 7a). Specifically,
thermoelectric
units 148 transfer the heat to heat exchanger 22 which dissipates the
extracted
heat into the air. The two fans 50 are inserted in the heat sink 22 and force
air
over the surface of the fins 58 and facilitates the dissipation of the heat
into the
air. Referring to the diagrammatic representation in Figure 10, the cold fluid
from
chamber 112 is circulated through a patient wrap 200 which is placed directly
on the area of the patient to be treated. The cold fluid is drawn up from the
cooling chamber 112 by pump 160 and delivered to the wrap or cooling blanket
200 through tube 174. The water returns from the blanket 200 to housing
chamber 112 in cooling module 56 through the return tube return line 172.
Water reservoir 34 is provided with a reserve of fluid which ensures a full
flow
circuit to maximize pertormance and prevent damage to the apparatus.
Chamber 112 in the cooling module housing 110 has a volume substantially
smaller than the fluid containing volume within reservoir 34. The refrigerant
is
not circulated directly through reservoir 34 as in many of the prior art
devices but
rather the reservoir is in flow communication with cooling module 56 so that
the
reservoir acts as sink or source for when a condition of an excess or deficit
respectfully of refrigerant circulated through the patient blanket exists.
This is
best seen in the block diagram of Figure 10. This feature, in addition to the
fact
that the refrigerant in the reservoir is not cooled and the feature of the
cooling
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4
module and pump assembly having a configuration to ensure a vigorous flow of
refrigerant directly over the cooled surface gives a significantly improved
cooling
efficiency over the prior art devices.
Power to cooling apparatus 20 in Figure 1 a is controlled by onloff
switch 38. When activated the device runs at maximum cooling. There are no
user/operator adjustments on the units. The two power supplies 44 provide
power to the control circuit and the control circuit in turn controls the
thermoelectric modules 148, fans 50 and pump 160. The system is designed to
maximize pump-motor life and provide the preset flow rate conditions (4.0 to
4.5
gallons per hour). Referring again to the diagrammatic representation in
Figure
10, control circuit 46 achieves this by monitoring pressure/flow sensor 132
and
regulating the supply voltage to pump 160 to maintain water flow between
cooling module 56 and patient blanket 200 without exceeding the maximum
voltage limitations. Should the voltage remain at the maximum for longer than
3.0 minutes a clearing cycle is initiated. The pump voltage is switched on for
8
seconds at 5.5 volts and off for 1 second. This cycle continues until the flow
returns to normal operating levels. Details of the operating logic are shown
in
the flow diagram in Figure 11.
The smooth, continuous opposing walls 98 of heat exchanger 22
conduct heat from the outer hot surfaces 152 of thermoelectric units 148
through
the triangular shaped overlapping sections 94 and the heat is conducted into
the
fin sections having air gaps between adjacent fins to dissipate heat. Thus,
heat
exchanger 22 is provided with very efficient heat dissipation by designing the
heat exchanger with similarly shaped plates which have an overlapping solid
portion which very efficiently conducts heat from the thermoelectric units to
the
air cooled finned section. When tapered housing 110 with thermoelectric units
148 engaged against the open faces is inserted into chamber 52 with the
thermoelectric units engaged against the O-rings in housing 110, the matching
tapered shape of chamber 52 acts to lock the cooling assembly in place and
provides a tight fit which ensures good thermal contact between the cooling
module and the heat exchanger. The outer surface 152 of thermoelectric units
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148 are preferably coated with thermal joint compound prior to being inserted
into chamber 52 to ensure good heat transfer between thermoelectric units 148
and heat exchanger 22.
Those skilled in the art will appreciate that numerous alternative
embodiments of the present cold therapy device may be constructed and still
fall
within the scope of the present invention.
Figures 12a to 12c illustrate a triangular cooling chamber housing
202 with three thermoelectric units 148 and water inlet 204 and outlet 206.
Figures 13a and 13b illustrate a four-sided cooling chamber 210
provided with four thermoelectric units 148. The corresponding heat exchanger
212 is provided with four sections similar to sections 94 in heat sink 22 in
Figure
3a to provide efficient heat transfer from cooling chamber 210 to the finned
portion of the heat exchanger (not shown). Figure 14 illustrates an eight-
sided
cooling chamber 220 provided with eight thermoelectric units 148. These
embodiments of the cooling chamber are advantageous for increasing cooling
capacity. The cooling units are tapered as are the corresponding heat
exchanger chambers in the heat exchangers into which the units are inserted.
Figures 15 to 17 illustrate alternative embodiments of the heat
exchanger which may be constructed according to the present invention. In
Figure 15, four plates 321 shaped as symmetric trapezoids are overlapped as
shown and triangular-shaped corner portions 324 have a continuous outer wall
326 which can conduct heat to the finned section comprising alternating metal
plate 321/air gaps 328 where the heat is dissipated. Four surfaces 326 may be
used to dissipate heat from heat sources adjacent to each surface. Figure 16
illustrates the same principle but using three plates 330 instead of four. The
structure of Figure 17 provides a heat transfer surface 326 produced by
overlapping metal plates 340 to form two triangular shaped sections 342
comprising alternating plates in contact with each other.
Figures 18 to 21 illustrate another embodiment of a heat
exchanger constructed in accordance with the present invention. In this
embodiment, a single plate 390 is provided with cut-out sections 392 and 394.
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From Figure 19 it can be seen that plate 390 includes an inclined lip 396 in
the
cut-out section 394 on opposed edges. Referring to Figure 21, when a plurality
of the plates are assembled together, adjacent lip portions overlap to provide
good thermal and mechanical contact between the lips 396. Holes 392 define
fan receptacles while lips 396 and cut-out portions 394 define a central
cooling
chamber into which a cooling module is inserted (not shown). As with the
previously described cooling chambers, the geometry of lips 396 and the
tapered module provides good heat transfer to the air gaps 398 located between
adjacent plates spaced from lips 336. Lips 336 are machined to provide a
smooth uniform tapered surface. Dimples 391 are located on the bottom side of
plate 390 which act as spacers in the stack. In heat exchanger 390 the solid
portion is defined by the narrow overlapped lips 396.
It will be understood that the substantial improvement in heat
dissipation achieved with the heat exchangers disclosed herein is obtained by
the combination of a solid surface (to which good thermal contact is made by
the
heat producing object) which extends into a finned heat dissipation area. The
number of solid sections in any one heat exchanger may be tailored to
accommodate any number of objects from which heat dissipation is desired. The
configuration in Figure 16 may be used to cool three objects, the arrangement
in Figure 15 may be used to cool four objects making thermal contact at
positions 326. The preferred embodiments disclosed herein utilize aluminum
plates provided with dimples extending transversely in both directions from
the
plane of the plate. Stacking the plates provides a solid central section with
a
finned section having air gaps between the plates except at the locations
where
the plates contact the dimples of the adjacent plates. However, it will be
appreciated that a solid block could be machined to provide both a solid
portion
and the finned section as an alternative to use of multiple plates disclosed
herein.
Another embodiment of a cooling device is shown in Figures 22 to
24. Referring first to Figure 22, a heating and cooling device constructed in
accordance with the present invention is shown at 300. Apparatus 300 is a
table
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top plug-in unit which operates with between 50 to 200 watts input power and
provides a larger surface area pad 302 having a heated section 304 adjacent to
a cooled section 306. A power supply 308 provides power through electrical
leads 315 to a thermoelectric unit 310 located between two identical water
pumps 312 and 314. Pump 312 through which the heated water flows is in flow
communication with a heat exchanger 316 provided with a fan 318 for
dissipating excess heat. Power supply 308 provides power to fan 318 through
leads 319. Water is supplied to the hot and cold sides from a water tank 320
and
a microprocessor (not shown) may be integrated into the system for temperature
control.
Figures 23 and 24 show in greater detail the hot side of the water
pump system comprising pump 312 having a motor housing 336, and a housing
338 attached to motor housing 336. Housing 338 defines a first chamber 340
and an impeller enclosure 342. Chamber 340 is separated from impeller
enclosure 342 by a disc 344 having a central aperture 346 to provide a fluid
flow
pathway between chamber 340 and impeller enclosure 342. Housing 338 has
an open end portion 343 (Figure 24) into enclosure 342 and thermoelectric unit
310 is attached to housing 338 at open end portion 343. Side 326 of
thermoelectric unit 310 is cooled and side 328 is heated when the current is
switched on. Pump 312 includes an impeller 348 mounted for rotation on a motor
shaft 350 which passes through a seal 352 into housing 338 where it is
connected to the motor.
Impeller 348 is spaced from surface 328 of the thermoelectric unit
by about 1 mm, best seen in Figure 23. An O-ring 354 between thermoelectric
unit 310 and housing 338 provides a water seal.
Referring again to Figure 22, the fluid flow system includes a large
water inlet tube 358 to introduce water from tank 320 into first chamber 340
in
housing 338. This inlet allows for cross-flow exchange of liquid and air but
does
not provide recirculation. Referring now to Figure 23, an air escape
passageway
360 extending from enclosure 342 to the interior of tube 358 is provided for
exhausting trapped air or allowing air to vent out of the pump 312 thereby
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permitting the system to automatically prime and provide a static pressure on
the
system. Passageways 364 extend through the side walls of housing 338 which
provide fluid flow communication between first chamber 340 and tubes 366 and
382 shown in Figure 24. Similarly, passageways 370 seen in Figure 23 extend
through the side walls of housing 338 to provide fluid flow communication
between impeller enclosure 342 and water outlet tubes 372 and 378 most visible
in Figure 24.
With reference to Figure 22, water inlet tubes 358 extend up
through the bottom of tank 320 and each has an end portion 322 which is
spaced above the water level. Tubes 358 are provided with holes 324 just above
the bottom of tank 320, more clearly visible in Figure 23. Water flows through
from tank 320 down through holes 324 into inlet tubes 358 into first chamber
340, through passageway 346 into impeller enclosure 342 and passes over
heated/cooled surfaces 328 and 326 respectively of thermoelectric unit 310 and
out of water outlet tubes 372. This water flow system, comprising inlet tube
358,
chamber 340, enclosure 342, air exhaust 360 and recirculation tubes 366, 372,
378 and 382 provides for cross-flow exchange of liquid and air but does not
provide for recirculation between tank 320 and the pumps.
When device 300 is assembled as shown in Figure 22, pump 314
is attached adjacent to side 326 of thermoelectric unit 310 and the pump is
essentially identical to pump 312 just described above and water circulated
over
surtace 326 of the thermoelectric unit is cooled except when the water does
not
pass through heat exchanger 316. Tubes 378 and 382 on one side of pump 312
conduct heated water to heat exchanger 316 while for the cooled side with pump
314 the corresponding recirculation tubes (not shown) would not be used. Tubes
366 and 372 on the other side of pump 312 recirculate heated water to and from
heated section 304 of water bag 302 and the corresponding tubes 366' and 372'
on pump 314 recirculate cold water to and from the cooled section 306 of pad
302.
The configuration of pumps 312 and 314 each with impeller 348
located adjacent to opposite sides of thermoelectric unit 310 is very
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,
advantageous in that it provides significantly more efficient heat transfer
between the thermoelectric unit and the water compared to previous designs in
which the pump is spaced away from the water heater and/or water cooler.
Rotating impeller 348 right adjacent to the surtace of thermoelectric module
310
provides enhanced heat transfer (fluid shear against the heated/cooled
surtace)
into the fluid thereby increasing the efficiency and cooling power over prior
art
devices. The centrifugal effect created by the rotation of the impeller acts
to
create a pressure differential to give a pumping action useful for mixing the
heat
transfer liquid and for pumping the fluid through the systems to the
components
being cooled and heated. Using a single thermoelectric unit 310 to both heat
and cool the water with pumps 312 and 314 mounted on either side of the unit
provides a more compact system.
In a preferred embodiment of heating and cooling device 300
thermoelectric unit 310 is a Melcor CP 1.4-127-045L or similar device rated at
120 Watts with 15 Volts and 8 amps and a DC motor used to drive impeller 348
operates at 15 Volts below one ampere.
With appropriate selection of power levels and components such
as heat exchanger 316 the water heating and cooling may be provided within
safe physiological limits without the need for sophisticated and costly
temperature and feedback control systems. Flexible pad 302 may be secured to
any part of the body using tape, VELCROT"" straps and the like and may be
readily deformed to fit the contours of the body. Apparatus 300 may be
modified
so that the hot and cold sections 304 and 306 of water bag 302 are
periodically
switched to provide temporal temperature modulation in addition to spatial
temperature modulation. This may be done for example by connecting a heat
exchanger and fan to pump 314 so that the hot and cold sides of the apparatus
are mirror images of each other. Then the hot and cold sides may be rapidly
switched by means of a four way ball valve used to redirect and interchange
the
hot and cold fluid paths.
Another embodiment of the system may be provided which uses
air cooling to cool the hot side of unit thermoelectric unit 310 (not shown).
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..
4
Figures 25 to 29 illustrate an alternative embodiment of a cooling
module 400 which may be used in the hot/cold therapy device of Figure 22.
Module 400 includes a housing 402 comprising two matching sections 404 and
406 with section 404 provided with fluid flow passageways 410 and 412 and
section 406 provided with passageways 414 and 416. A spigot 418 is attached
to the housing at one end of channel 410 and a spigot 424 is attached at the
other end. Similar spigots are located at the ends of channel 414. Each
section
404 and 406 is provided with an inner O-ring groove 422 each to receive
therein
a separate O-ring 420 and each housing section defines an inner surface 408
sealed by the O-rings when the unit is assembled as in Figure 26a. Sandwiched
between sections 404 and 406 is a thermoelectric unit 426 having two opposed
surtaces 428 and 430 wherein one is heated and the other cooled when a
voltage is applied across the unit. When the cooling unit is assembled
together
with the thermoelectric unit 426, a gap 432 exists between inner surfaces 408
and the opposing surtace of the thermoelectric unit. Pump motors 436 are each
provided with an impeller housing 438 housing an impeller (not shown) and the
impeller housing of two pumps are inserted into channels 412 and 416 and
sealed by O-rings 442, best seen in Figure 25. Each pump 436 has an outlet
spigot 440 to which a water hose is connected which connects the unit to the
coolinglheating blanket and/or a heat exchanger (not shown).
With reference to Figure 25, fluid returns from the patient blanket
(not shown) into spigot 418 through hose 460. Air bubbles are separated and
return to the fluid reservoir (not shown) through spigot 424 and air return
line
450 attached to the spigot (Figure 28). Fluid is drawn across the surface 428
of
the module 426. The gap 432 between housing surface 408 and module surface
428, best seen in Figure 26a, is small enough to ensure the shear force of the
water breaks the layer of water resting against the module surface and
maximizes heat transfer. The refrigerant is cooled as it is uniformly drawn
over
the surface 428 of module 426 into channel 412 where it is drawn into pump 436
and returned to the patient blanket via pump outlet 440. Fluid returning from
the
blanket through hose 460 into spigot 418 is allowed to fill reservoir 410 with
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sufficient fluid so as to provide a uniform flow across the entire cooled
surface
428 (Figure 26c) of thermoelectric Pettier unit 426 to maximize cooling of the
fluid. The fluid contacts surface 428 at entry gap 411 and is drawn across the
surface 428 and exits through exit gap 413 into reservoir or channel 412, see
Figures 26a and 29. In this way the refrigerant is vigorously flowed across
the
cooled surface.
In all the cooling modules disclosed herein the significant
improvement in cooling efficiency is achieved by flowing the refrigerant
directly
and vigorously across the cooled surface of the refrigeration unit. The
cooling
module of Figure 5 achieves this by the impeller 164 being spaced from cooled
surface 150 of thermoelectric unit 148 on the inside of chamber 112 with
refrigerant being circulated across the chamber and up into impeller housing
162
and out through exit port 166. The cooling module of Figure 24 achieves
vigorous flow across surface 328 of thermoelectric unit 326 by rotating in a
plane
parallel surface 328 a short distance away from the surface. Thus, it will be
appreciated that suitable placement of the pump to achieve good flow across
the
cooled surface is important for realizing the benefits of this invention.
Therefore, while the devices for producing hot and/or cold wraps
for alleviating pain has been described and illustrated with respect to the
preferred and alternative embodiments, it will be appreciated by those skilled
in
the art that numerous variations of the invention may be made which still fall
within the scope of the invention described herein.
30
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