U.S. patent number 3,658,075 [Application Number 05/093,692] was granted by the patent office on 1972-04-25 for dishwasher having improved condensation means.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to James W. Jacobs.
United States Patent |
3,658,075 |
Jacobs |
April 25, 1972 |
DISHWASHER HAVING IMPROVED CONDENSATION MEANS
Abstract
A dishwasher having an improved water condensation arrangement
for use therewith including a dishwasher chamber having fluid
circulating means together with means for providing a washing,
rinsing and drying function in the compartment. A volatile fluid
plate-type heat exchanger including continuous interconnected flow
passages therein having a lower evaporator section in heat exchange
relation with a wall of the chamber and an upper condenser section
located in a cooling air duct between the chamber and the outer
casing so as to be in heat exchange with a source of circulating
cooling air to effect removal of moisture from the vapor in the
dishwashing chamber to facilitate the drying of dishes within the
chamber.
Inventors: |
Jacobs; James W. (Dayton,
OH) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
22240243 |
Appl.
No.: |
05/093,692 |
Filed: |
November 30, 1970 |
Current U.S.
Class: |
134/107; 62/331;
165/47; 165/104.12; 134/115R; 165/104.21 |
Current CPC
Class: |
A47L
15/483 (20130101); F28D 15/0266 (20130101); F28D
15/0233 (20130101) |
Current International
Class: |
A47L
15/48 (20060101); B08b 003/02 (); B08b
015/00 () |
Field of
Search: |
;134/107,115
;62/331 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,255,254 |
|
Nov 1967 |
|
DT |
|
113,869 |
|
Apr 1945 |
|
SW |
|
Primary Examiner: Bleutge; Robert L.
Claims
What is claimed is:
1. A dishwasher including walls enclosing a dishwashing chamber and
defining an access opening, a door for enclosing the dishwashing
chamber, means for spraying in said chamber, means for supporting
dishes in exposed relationship to said spray means, one of said
walls forming a sump below said support means and having a sump
opening selectively connected to a drain, means connected to said
sump opening for supplying cleansing fluid to spray means for
spraying dishes in said support means whereby cleansing fluid
sprayed on said dishes gravitationally returns to said sump,
heating means for drying the dishes with said door closed by
vaporizing the cleansing fluid on said dishes after the dishes have
been sprayed, cooling air duct means adjacent said chamber, a
closed volatile refrigerant heat exchanger having an upper
condenser section positioned in said cooling air duct means in
spaced relationship with said dishwashing chamber and a lower
evaporator section positioned in direct thermal contact with said
dishwashing chamber, a volatile refrigerant in said heat exchanger,
said upper condenser section and said lower evaporator section each
having refrigerant flow passage means therein, first and second
conduit means interconnecting said condenser section passage means
and said evaporator section passage means whereby a closed
continuous recycling flow passage network for the refrigerant is
established, said upper condenser section passage means adapted to
contain said refrigerant in gaseous form to operate as a heat
dissipator and said bottom evaporator section passage means adapted
to contain said refrigerant in liquid form to operate as a heat
absorber and cool said chamber wall for condensing moisture from
said cleansing fluid vapor, said first conduit means providing a
passage for said refrigerant in liquid form from said upper
condenser section to said lower evaporator section, said second
conduit means providing a passage for said refrigerant in gaseous
form from said lower evaporator section to said upper condenser
section, said refrigerant upon absorbing heat from the chamber wall
rising in gaseous form in said second conduit means to said upper
condenser section whereby the refrigerant is condensed back to
liquid form for flow of said refrigerant by gravity through said
first conduit means providing near isothermal continuous heat
transfer such that the relative humidity of said cleansing fluid
vapor in said chamber is decreased and the drying of said dishes is
expedited.
2. A dishwasher including fixed top, bottom, rear and side walls
enclosing a dishwashing chamber, a door for enclosing the
dishwashing chamber, means for spraying in said chamber, means for
supporting dishes in exposed relationship to said spray means, said
bottom wall forming a sump below said support means and having a
sump opening selectively connected to a drain, means connected to
said sump opening for supplying cleansing fluid to said spray arm
and said spray tower for spraying dishes in said support means
whereby fluid sprayed on said dishes gravitationally returns to
said sump, heating means for drying the dishes with said door
closed by vaporizing the fluid on said dishes after the dishes have
been sprayed, cooling air duct means adjacent a side wall of said
chamber, a closed volatile refrigerant heat exchanger positioned in
sail cooling air duct means, said heat exchanger being of the
unitary plate-type having interconnected refrigerant flow passages
therein including a lower evaporator section, an intermediate
section and an upper condenser section; said upper condenser
section spaced from said chamber side wall and adapted to contain
said refrigerant in gaseous form in its passages to operate as a
heat dissipator to the cooling air in said duct means, said bottom
evaporator section being in thermal contact with said chamber wall
and adapted to contain said refrigerant in liquid form in its
passages to operate as a heat absorber and cool said chamber wall
for condensing moisture from said cleansing fluid vapor, said
intermediate section providing for the separation of the gaseous
and liquid refrigerant, said intermediate section providing a first
passage for said refrigerant in liquid form from said upper
condenser section to said lower evaporator section, said
intermediate section providing a second passage for said
refrigerant in gaseous form from said lower evaporator section to
said upper condenser section, said refrigerant upon absorbing heat
from said chamber wall rising as a vapor in gaseous form in said
second passage to said upper condenser section such that said
refrigerant is condensed back to liquid form for flow of said
refrigerant by gravity through said first passage providing near
isothermal continuous heat transfer such that the relative humidity
of said cleansing fluid vapor in said chamber is decreased and the
drying of said dishes is expedited.
3. A dishwasher including fixed top, bottom, rear and side walls
enclosing a dishwashing chamber, a door for enclosing the
dishwashing chamber, means for spraying in said chamber, means for
supporting dishes in exposed relationship to said spray means, said
bottom wall forming a sump below said support means and having a
sump opening selectively connected to a drain, means connected to
said sump opening for supplying cleansing fluid to said spray arm
and said spray tower for spraying dishes in said support means
whereby fluid sprayed on said dishes gravitationally returns to
said sump, heating means for drying the dishes with said door
closed by vaporizing the fluid on said dishes after the dishes have
been sprayed, cooling air duct means adjacent a side wall of said
chamber, a closed volatile refrigerant heat exchanger positioned in
said cooling air duct means, said heat exchanger being of the
unitary plate-type and generally rectangular in shape having
interconnected refrigerant flow passages therein including a lower
evaporator section, an angularly offset intermediate section and an
upper condenser section bent in the plane of said bottom section so
as to be spaced from said chamber side wall; said upper condenser
section adapted to contain said refrigerant in gaseous form in its
passages to operate as a heat dissipator to the cooling air in said
duct means, said bottom evaporator section being in thermal contact
with said chamber wall adjacent said bottom wall and adapted to
contain said refrigerant in liquid form in its passages to operate
as a heat absorber and cool said chamber wall for condensing
moisture from said cleansing fluid vapor, said intermediate section
providing a generally parallelogram-shaped welded web for the
separation of the gaseous and liquid refrigerant, said intermediate
section welded web having its end substantially parallel with the
vertical side edges, said heat exchanger providing a first vertical
passage adjacent one side edge of said heat exchanger for said
refrigerant in liquid form from said upper condenser section to
said lower evaporator section, said intermediate section providing
a second vertical passage adjacent the opposite side edge of said
heat exchanger for said refrigerant in gaseous form from said lower
evaporator section to said upper condenser section, said
intermediate welded web forming a sloped header passage in said
condenser section to provide gravity flow of said refrigerant in
liquid form to said first passage, said refrigerant upon absorbing
heat from said chamber wall rising as a vapor in gaseous form in
said second passage to said upper condenser section such that said
refrigerant is condensed back to liquid form for flow of said
refrigerant by gravity through said first passage providing near
isothermal continuous heat transfer such that the relative humidity
of said cleansing fluid vapor in said chamber is decreased and the
drying of said dishes is expedited.
4. A dishwasher including fixed top, bottom, rear and side walls
enclosing a dishwashing chamber, a door for enclosing the
dishwashing chamber, means for spraying in said chamber, means for
supporting dishes in exposed relationship to said spray means, said
bottom wall forming a sump below said support means and having a
sump opening selectively connected to a drain, means connected to
said sump opening for supplying cleansing fluid to said spray arm
and said spray tower for spraying dishes in said support means
whereby fluid sprayed on said dishes gravitationally returns to
said sump, heating means for drying the dishes with said door
closed by vaporizing the fluid on said dishes after the dishes have
been sprayed, an outside cooling air duct partially formed between
the back wall of said chamber and the rear wall of said dishwasher,
a closed volatile refrigerant heat exchanger positioned in said
cooling air duct between said chamber back wall and said dishwasher
rear wall, impeller means in said duct for initiating a circulation
of outside air flow through said duct, said heat exchanger being of
the unitary plate-type and generally rectangular in shape having
interconnected horizontal and vertically disposed refrigerant flow
passages of the waffle-type therein including a lower evaporator
section, an angularly offset intermediate section and an upper
condenser section bent in the plane of said bottom section so as to
be spaced from said chamber side wall; said upper condenser section
adapted to contain said refrigerant in gaseous form in its passages
to operate as a heat dissipator to the cooling outside air in said
duct, said condenser section having slotted louvers formed in the
welded web areas between said flow passages to increase the rate of
heat transfer from condenser section to the outside air flow in
said duct, said bottom evaporator section being in thermal contact
with said chamber wall adjacent said bottom wall and adapted to
contain said refrigerant in liquid form in its passages to operate
as a heat absorber and cool said chamber wall for condensing
moisture from said cleansing fluid vapor, said intermediate section
providing a generally parallelogram-shaped welded web for the
separation of the gaseous and liquid refrigerant, said intermediate
section welded web having its ends substantially parallel with the
vertical side edges, said heat exchanger providing a first vertical
passage adjacent one side edge of said heat exchanger for said
refrigerant in liquid form from said upper condenser section to
said lower evaporator section, said intermediate section providing
a second vertical passage adjacent the opposite side edge of said
heat exchanger for said refrigerant in gaseous form from said lower
evaporator section to said upper condenser section, said
intermediate welded web forming a sloped header passage in said
condenser section to provide gravity flow of said refrigerant in
liquid form to said first passage, said refrigerant upon absorbing
heat from said chamber wall rising as a vapor in gaseous form in
said second passage to said upper condenser section such that said
refrigerant is condensed back to liquid form for flow of said
refrigerant by gravity through said first passage providing near
isothermal continuous heat transfer such that the relative humidity
of said cleansing fluid vapor in said chamber is decreased and the
drying of said dishes is expedited.
Description
This invention relates to dishwashers and more particularly to a
volatile fluid heat exchanger arrangement to effect condensation of
water vapor in the dishwasher chamber.
In dishwashing apparatus cleaning chambers such as prior art U.S.
Pat. No. 2,390,757 issued Dec. 11, 1945, it has been recognized as
desirable to minimize the amount of steam or vapor which escapes to
the area surrounding the dishwasher, by condensing the volatile
fluid in the chamber and returning it to a liquid form to the sump
portion, as a result of lowering the wet bulb temperature within
the chamber and thereby facilitate the drying of dishes within the
chamber.
In the design of dishwashers, as stated in my issued U.S. Pat. No.
3,068,877 dated Dec. 18, 1962, there are two drying systems which
are prevalent, one wherein the access door for the dishwasher is
opened at the beginning of the drying cycle and the other wherein
the door is closed throughout the dishwashing cycle. Maintaining
the door in a closed condition provides the advantage of reducing
the exhaust of some of the steam from the dishwashing chamber and
therefore eliminates some of the damage arising when condensate
forms on the relatively cool surfaces of cabinets, countertops,
etc. surrounding the dishwasher. The drying portion of a
dishwashing cycle, however, is generally longer in those machines
in which the door is closed during drying. It is the purpose of
this invention to eliminate the problems of exterior condensation
and to accelerate drying in a closed door drying system without
having to materially modify the construction of the dishwasher
cabinet or resort to an expensive separate motor-driven fan,
etc.
Accordingly, it is an object of this invention to provide a
dishwasher having a continuous volatile fluid heat exchange means
for condensing moisture from the air within the dishwashing
chamber.
It is also an object of this invention to provide a heat exchanger
for dishwashing machines having a hermetically sealed closed
circuit heat exchange unit of the plate-type construction having
upper and lower sections interconnected by continuous flow passages
adapted to contain a volatile refrigerant, the upper section of the
heat exchanger being located in a vertical cooling air duct formed
by spaced walls of the dishwashing chamber and outer cabinet, and
adapted to operate as a heat dissipator or condenser while the
lower section of the plate-type heat exchanger being in thermal
contact with the dishwasher chamber wall and adapted to contain a
liquid refrigerant to operate as a heat absorber or evaporator for
cooling a portion of the chamber wall and thereby provide gravity
flow of condensate to the sump of the dishwasher chamber.
Other features and advantages of the invention will be apparent
from the following description of a certain embodiment taken in
combination with the accompanying drawings, wherein a preferred
embodiment of the present invention is clearly shown.
IN THE DRAWINGS
FIG. 1 is a generally schematic representation of a dishwasher
incorporating the invention;
FIG. 2 is an enlarged front elevational view of the heat exchange
plate of the present invention;
FIG. 3 is a cross-sectional view taken on lines 3--3 of FIG. 2;
FIG. 4 is a fragmentary cross-sectional view similar to FIG. 3 of a
modification of the heat exchange plate;
FIG. 5 is a view similar to FIG. 4 of still another modification of
the heat exchange plate.
In accordance with this invention and with reference to FIG. 1, a
dishwasher 10 having an outer cabinet 11 including a top 12, side
panels one of which is partially indicated at 13, a rear panel 14
and a base portion 16 adapted to include the dishwashing chamber
shown generally at 18. The dishwashing chamber 18 is a generally
box-like receptacle having a depressed bottom defining a sump 20.
The dishwashing chamber 18 has also an access opening 22 in the
front wall thereof above lower front panel 23. Closing the opening
is a dishwasher door, shown generally at 24. The door 24 may be
hinged and latched to the side panels of the dishwasher 10 in any
conventional manner and is adapted to be opened by the handle 26.
In order to ensure watertight connection between the dishwashing
chamber 18 and the door 24 a gasket 28 may be provided in arranged
periphery about the opening 22.
Although this invention is not to be limited to a particular type
of dishwasher, for purpose of illustration the dishwasher 10 is
shown provided with a revolving spray arm 30 located beneath a
lower utensil support rack 32 and a rotating spray column or tower
34 affixed to the spray arm and extending upwardly through a guard
portion 36 of the lower rack permitting the removal of the lower
rack from the dishwashing chamber. The spray column 34 is formed
within a large bulbous housing or header portion 38 at the top
thereof having an upper spray nozzle or outlet 40, aimed toward an
upper utensil support rack 42 and upper chamber wall 43 together
with a plurality of outlets or ports 44 around the periphery of the
header 38. The reaction effect of the water sprayed from the spray
arm ports 46 will cause the water distribution means, including the
spray arm 30 and spray column 34 to rotate. The water distribution
system is the type disclosed in the commonly assigned Braden et al.
U.S. Pat. No. 3,292,645 issued Dec. 20, 1966, the disclosure
thereof being incorporated herein by reference.
The water distribution system of the dishwasher 10 includes a pump
assembly 50 driven by suitable drive means, for example, a
reversible electric motor 52 disposed below the pump assembly in
the machinery compartment 54. The pump assembly 50 includes the
rotatable horizontal spray arm 30 thereon to which fluid is
supplied from the sump region 20 for distribution through the
washing chamber 18 during a cleaning cycle of the dishwasher as
established by a sequence or timer control means 56 having a timer
control knob 58 located on the front of the dishwasher door 24.
Also within the dishwashing chamber 18 is a heater 59 which is
selectively energized at the conclusion of the wash portion of the
cycle to raise the temperature within the dishwashing chamber 18 to
dry the dishes therein. It is of course possible to energize the
heater 59 periodically throughout the washing portion of the cycle
to maintain desired higher washing fluid temperatures within the
chamber 18. At the conclusion of the dishwashing cycle, the motor
is reversed to permit the pump 50 to remove water from the sump 20
to any suitable remote drain. The dishwashing cycle may be
initiated by a start button to energize the timer which thus
programs sequentially the desired dishwashing cycle. For additional
details on the dishwashing mechanism outlines broadly hereinabove,
reference may be had to the Braden et al. patent mentioned
above.
During the period that water is being circulated from the sump 20
to the spray arm 30 and spray tower 34, considerable steam is
involved depending, of course, on the temperatures of the washing
fluid being circulated. When the surfaces of the dishes and
utensils carried by the racks 32 and 42 have been sufficiently
cleaned and rinsed, it is then desirable to effect a rapid drying
of the cleansed dishes. If the door 24 closing the steam or vapor
filled dishwashing chamber 18 were opened, steam and vapor thus
released would flow into the surrounding area to condense on the
first cool surface encountered. As explained in the above-mentioned
U.S. Pat. No. 3,068,877, it is desirable to keep the door closed
during the drying operation of the dishwashing cycle and applicant
has provided a novel plate-type heat exchanger or dehumidifier
generally indicated at 60 to be mounted on the back wall 62 of the
chamber 18 for removing moisture from the vapor within the
dishwashing chamber when the dishes are being dried.
The plate-type heat exchanger 60 is preferably of the roll-forged
or roll-bonded construction, in which two sheets of metal 64 and
66, such as aluminum, are integrally welded together to form a
single plate which has a plurality of passages in the spaced walls
forming volatile fluid horizontal and vertical passages or conduits
and having the walls integrally joined together at a multiplicity
of spaced points or welded areas indicated at 68 for supporting
them in definite spaced relation. Such a plate-type heat exchanger
is shown in developed plan in FIG. 2; and the two sheets from which
it is formed are spaced from each other to form a charging opening
69 located on the right-hand edge in FIG. 2 and which is pinch
closed and heli-arc welded after charging with volatile fluid which
in the preferred form is a refrigerant of the type having the
designations R-12, R-22 or R-114 commonly known as Freon.
The heat exchanger is formed as a flat plate as shown in FIG. 2 and
is bent on rounded curves as indicated by the fold lines A and B to
provide an upper condenser plate section 70 and lower evaporator
plate section 74 joined by intermediate bonded web section 72. As
seen in the view of FIG. 2, the lower plate section 74 is provided
with apertures 76 for mounting in direct heat exchange contact with
the lower region of the chamber wall 62 adjacent bottom wall 63 by
suitable means such as bolts 78. The angularly offset intermediate
section 72 extends away from the chamber wall 62 such that its
upper plate section 70 is in a plane parallel to and offset from
the plane of the lower plate section 74. As seen in FIG. 1 the
upper plate section 70 of the heat exchanger 60 is mounted on
spacer studs 80 extending through apertures 82 of the heat
exchanger 60 adjacent the upper wall 43 of the dishwashing chamber
such that the upper plate section 70 is substantially aligned in a
vertical flue or duct 81 defined by the rear panel 14 of the
cabinet and the back wall 62 of the chamber 18 so as to be
substantially coextensive with the back wall 62.
The upper condenser plate section 70 is shown provided with a
larger substantially rectangular refrigerant condenser passage
portion 83 of the waffle-type construction having the charging
opening 69, located in its upper right-hand corner of plate 70,
leading to upper horizontal header passage 86, parallel to the
series of horizontal passages 87 connecting the upper ends of
vertical passages 88 which extend downward to the sloped header 89
provided for receiving the condensed liquid refrigerant. Sloped
header 89 connects to a vertical liquid refrigerant passage 90
formed by the intermediate welded web 92 of section 72. The web 92
is shaped in the form of a parallelogram and has a welded extension
94 leading to the lower left-hand corner of plate 74 and connects
to a lower horizontal header 96 of a lower waffle-type refrigerant
evaporator passage portion of plate 74, designated by the reference
character 98. An evaporated refrigerant connecting passage 99 is
provided opposite the liquid refrigerant connecting passage 90 and
extends vertically to the upper right-hand corner of condenser
plate section 70 to connect to the upper header passage 86, by
means of web extension 100, communicating with the upper
waffle-type condenser portion 83. This arrangement provides good
distribution of both the vapor and liquid portions of the
refrigerant.
Cooling air is provided for the plate condenser section 70 from the
atmosphere surrounding the dishwasher 10. A cooling air louvered
inlet 110 is formed in base portion 16 while an air outlet 112 is
vertically spaced from the inlet 110 to permit the cooling air to
return to the atmosphere after passing over the plate-type
condenser 70 in duct 81. It should be noted that in a modified form
of the invention an impeller 114, driven by motor 52 and an
L-shaped duct wall 116 could be utilized in a manner as taught in
applicant's above-mentioned U.S. Pat. No. 3,068,877 for example, to
increase the flow of cooling air over the condenser portion 83 of
the heat exchanger 60 if desired without departing from the scope
of the invention.
In operation, the liquid refrigerant in the waffle-type portion in
the evaporator plate section 74 evaporates to cool the plate and in
turn the lower portion of the chamber wall 62 which is in direct
thermal contact therewith. The refrigerant vapor flows upwardly
into the sloped header 106 and thence vertical passage 99 and into
the waffle-type portion 83 of the plate condenser 70 which is at a
lower temperature because of its spaced relation to the chamber
walls 62 and exposure to the cooling air flow in duct 81. The cold
junctions in the waffle-type portion 83 in the condenser plate
section condense the refrigerant vapor to a liquid and the liquid
flows by gravity to the sloped header 89 and vertical connecting
passage 90 to the lower evaporator portion 98 so that the heat
transfer action is continuous. Thus the refrigerant vapor gives up
its heat to the upper plate condenser section 70 and the liquid
refrigerant evaporates and extracts heat from the lower portion of
the chamber wall 62 by means of lower plate evaporator section 74.
The lower portion of wall 62 is thus below the dew-point of the
vapor in the chamber and moisture will thus condense from the vapor
and will fall by gravity to the lower wall 63 and consequently into
sump 20 where it may be removed to drain by the action of a
continuously or periodically operating pump 50. Of course, the pump
50 need not be operating throughout the drying cycle and the
condensate may be permitted to run by gravity to drain, if so
provided for.
By means of applicant's device the wet bulb temperature in the
chamber 18 is lowered without affecting the dry bulb temperature to
a significant degree. This can be shown by reference to a Bulkely
Psychrometric Chart wherein with a dry bulb temperature of
approximately 120.degree. F. and a condensing temperature of
90.degree. F. the relative humidity in the chamber would be of the
order of 30 percent. A reduction of the web bulb temperature to
80.degree. will reduce the relative humidity in the chamber to the
order of 17 percent and a further reduction of the wet bulb
temperature to 70.degree. F. will reduce the relative humidity to
something less than 5 percent.
A modified form of the upper condenser plate is shown at 118 in
FIG. 4 wherein slotted louvers 120 are formed in the welded areas
68 to increase the circulation of cooling air in the duct 81 to
increase the rate of heat transfer from the waffle-like condenser
portion 83 to the air. A still further modification of the upper
condenser plate 70 is shown at 122 in FIG. 5 wherein L-shaped fins
124 are incorporated on the plate as by welding to increase the
rate of heat transfer to the cooling air.
It will thus be seen that applicant has utilized the "heat pipe"
principle to provide a gravity flow plate-type heat exchanger which
operates almost isothermally. That is the volatile working fluid,
which in the preferred embodiment is a liquid refrigerant such as
R-12 (Freon-12), has a liquid temperature in the evaporation
section within the order of one or 2.degree. F. of being equal to
the vapor temperature of the refrigerant in the condenser section.
The result is that a near isothermal continuous heat transfer is
accomplished wherein the relative humidity of the cleansing fluid
vapor in the dishwashing chamber is decreased expediting the drying
of the dishes.
While the embodiment of the present invention as herein disclosed
constitutes a preferred form, it is to be understood that other
forms might be adopted.
* * * * *