U.S. patent number 3,657,899 [Application Number 05/045,662] was granted by the patent office on 1972-04-25 for ice making machine.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Taisei Hosoda, Kazuo Ioka, Hiroichi Osiyama, Hideo Uzuhashi.
United States Patent |
3,657,899 |
Hosoda , et al. |
April 25, 1972 |
ICE MAKING MACHINE
Abstract
Ice making machine for producing pieces of ice being provided
with a hollow evaporator supplied with a refrigerant and a
plurality of partitions secured onto the outer surface of the
evaporator so as to be vertically extended from the top to the
bottom thereof, thereby forming water channels therebetween. During
the period of ice formation, water is supplied to the channels and
refrigerant is supplied to the evaporator so that portions of the
water freeze to form pieces of ice. During the period of
harvesting, the water supply is discontinued and heated refrigerant
vapor is provided in the evaporator to remove the pieces of ice
therefrom.
Inventors: |
Hosoda; Taisei (Shimotsuga-gun,
JA), Uzuhashi; Hideo (Shimotsuga-gun, JA),
Osiyama; Hiroichi (Shimotsuga-gun, JA), Ioka;
Kazuo (Oyama, JA) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JA)
|
Family
ID: |
12988835 |
Appl.
No.: |
05/045,662 |
Filed: |
June 12, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Jun 13, 1969 [JA] |
|
|
44/55084 |
|
Current U.S.
Class: |
62/137; 62/348;
62/180; 137/392 |
Current CPC
Class: |
F25C
1/12 (20130101); G05D 9/12 (20130101); Y10T
137/7306 (20150401) |
Current International
Class: |
F25C
1/12 (20060101); G05D 9/12 (20060101); G05D
9/00 (20060101); F25c 001/14 () |
Field of
Search: |
;62/348,347,71,515,137,180 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wayner; William E.
Claims
We claim:
1. Ice making machine for producing pieces of ice comprising:
hollow evaporator means made of a material having a relatively high
thermal conductivity, the evaporator means adapted to be supplied
with refrigerant and having substantially vertically disposed side
walls;
side boards secured onto top and bottom surfaces of the evaporator
so as to be extended from said surfaces upwardly and downwardly,
respectively, and the side boards and the side walls of the
evaporator means forming ice making plates on which pieces of ice
are to be formed;
a plurality of partitions secured onto the ice making plates so as
to be vertically extended from the top to the bottom of the plates
and spaced apart from each other in substantially parallel manner
to form water stream channels therebetween, the side boards and
partitions being made of material having relatively lower thermal
conductivity than that of the evaporator means; said partitions
having a thickness which is reduced horizontally from the contact
point thereof with the side walls of the evaporator means outwardly
as well as vertically from the top to the bottom thereof;
water distribution means for supplying water onto the evaporator
means so as to flow through the channels on the ice making plates
in contact therewith and for circulating the supply of water;
and
refrigerant supply circuit means for selectively supplying heated
refrigerant vapor and liquid refrigerant to the evaporator
means.
2. Ice making machine according to claim 1, wherein the uppermost
distance between the side walls of the evaporator means is
relatively longer than the lowermost distance thereof.
3. Ice making machine according to claim 1, wherein a single side
board extends downwardly from the bottom surface of the evaporator
means.
4. Ice making machine according to claim 1, wherein the uppermost
extension of each partition is relatively longer than the lowermost
extension thereof.
5. An ice making machine according to claim 1, further including an
electrical control circuit for controlling the operation of said
water distribution means and said refrigerant supply circuit means
comprising means, responsive to the supply of water within said
water distribution means and the temperature within said machine,
for effecting and cutting off the supply of water and refrigerant
to said evaporator means.
6. An ice making machine according to claim 5, wherein said machine
further includes a water storage means for storing water to be
supplied to said evaporator means and includes water level sensor
means disposed within said water storage means;
said electrical control circuit including a source of power, a
temperature responsive switch connected thereto and respective
electrically controlled first and second valves, coupled with said
water distribution means and said refrigerant supply circuit means,
and being coupled to said power source through said temperature
responsive switch and to said water storage means through said
water level sensor means for controlling the flow of water and
refrigerant to said evaporator means, in response to the
temperature within said machine and the level of water within said
water storage means.
7. An ice making machine according to claim 6, wherein said
electrical control circuit further comprises a power coupling
means, coupled to said source of power, for supplying current to be
conducted through the water level sensor means of said water
storage means, a first switching means responsive to the current
flowing through said water level sensor means for effecting
exclusive application of energizing power to said first and second
electrically controlled valves.
8. An ice making machine according to claim 7, further including a
pump and a motor therefor, for pumping water from said water level
storage means, through said water distribution means, said first
switch means comprises a first switch connector connected in series
with said second electrically controlled valve for energizing said
second electrically controlled valve in response to a first
predetermined level of water in said water storage means.
9. An ice making machine according to claim 8, further comprising a
second switch means, coupled to said first electrically controlled
valve for controlling the energization of said first electrically
controlled valve in response to the temperature of said evaporator
means.
10. An ice making machine according to claim 9, wherein said first
switch means further includes an additional switch connected in
series with said pump motor for energizing said motor while
preventing the operation of said second electrically controlled
valve.
11. An ice making machine according to claim 10, wherein said water
level sensor means comprises a plurality of conductors each
displaced with respect to each other in the direction of the
surface of the water within said water storage means, a first of
which being connected to said power coupling means, while at least
one other conductor is connected to one terminal of a bridge
circuit, another terminal of which, opposite to said one terminal,
being connected to said power coupling means.
12. An ice making machine according to claim 11, wherein said first
switching means comprises a first relay coil connected to a first
pair of opposite terminals of said bridge circuit, a second pair of
which being connected to said one and another of opposite terminals
thereof, and wherein said bridge comprises a rectifier bridge, said
first switch means includes a pair of conductors respectively
connected to said first electrically controlled valve and to said
motor, while the movable connector thereof is coupled through said
power source to one of said contacts in response to the
energization of said relay coil.
13. An ice making machine according to claim 12, wherein said first
switch means further includes a second pair of switch contacts and
a movable arm therefor for controlling the water level at which
said relay coil becomes energized.
14. An ice making machine according to claim 13, wherein said ice
making machine further includes means for receiving ice from said
evaporator means and further including a wait switch responsive to
the wait of said received ice for deenergizing said electrical
control means in response to a predetermined quantity of ice
therein, and further including a compressor motor coupled to said
power supply for driving said refrigerant supply means for
maintaining the temperature within said machine at a predetermined
level.
15. An ice making machine according to claim 14, further including
a control temperature responsive switch connecting said power
source to the input of said electrical control circuit and wherein
said power coupling means comprises a transformer, the primary
winding of which is coupled to said power source and the secondary
winding of which is connected to one of said conductors and to said
bridge circuit.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an ice making machine, and more
particularly, to a commercial-type ice making machine for use in
hotels, restaurants and the like.
One type of conventional ice making machine for making a number of
pieces of ice consists of an ice forming plate disposed in inclined
relationship with respect to the bottom of a compartment, a water
distribution system for passing a uniform stream of water on the
outer surface of the ice forming plate from the upper portion
downwardly thereof, an evaporator located in contact with the
opposed surface of the ice forming plate opposite to the outer
surface thereof and an ice cutting means including heating mesh
wires placed at a position adjacent to the ice forming plate.
Such a conventional type of machine carries out basically two steps
of operation. First, a water stream is provided on the outer
surface of the ice forming plate, and at the same time, liquid
refrigerant is provided into the evaporator, so that a portion of
the water stream flowing over the outer surface of the plate may be
frozen to form a slab of ice thereon. As time passes, the slab of
ice grows larger. Secondly, the supply of water on the ice forming
plate is discontinued after a certain amount of ice has been built
up and the evaporator is then provided with heated refrigerant
vapor. Due to this second step, the surface of the ice forming
plate is gradually warmed, so that the slab of ice formed on and
contacted to the surface of the plate is melted, thereby falling
onto the surface of the heating mesh wires. Thus, the slab of ice
is cut into a plurality of cubes and falls into an ice storage
vessel.
The conventional machines are thus necessarily provided with ice
cutting means including heating mesh wires, thereby making it
difficult to provide a simplified and compact ice making machine.
Furthermore, there are disadvantages in that the efficiency of ice
making is very low since a certain amount of ice is converted back
to water during the cutting operation, while a large amount of
power is consumed by the heating mesh wires for cutting the slab of
ice into cubes.
SUMMARY OF THE INVENTION
It is an aim of the present invention to overcome the
above-mentioned problems and disadvantages of the conventional ice
making machines.
The underlying problems are solved in accordance with the present
invention by providing an ice making machine comprising a hollow
pillar-shaped evaporator into which refrigerant is supplied, a
plurality of partitions vertically disposed on the outer surface of
the evaporator so as to be extended from the top to the bottom
thereof, a water distribution system for providing a uniform water
stream over the outer surface of the evaporator, and refrigerant
supply means, which, in the period of refrigeration cycle,
operationally supplies low pressure liquid refrigerant to the
evaporator so as to cool the evaporator, thereby producing pieces
of ice separated by the plural partitions on the outer periphery of
the evaporator. During the harvesting cycle, the refrigerant supply
means operationally supplied heated refrigerant vapor to the
evaporator so that the pieces of ice may be removed from the
evaporator and directly fall into an ice storage vessel.
Accordingly, it is an object of the present invention to provide an
improved ice making machine which directly forms pieces of ice
without any means for cutting a slab of ice.
Another object of the present invention is to provide an ice making
machine with a high ice-making efficiency and low power
consumption.
It is still a further object of the present invention to provide an
ice making machine of relatively compact and simplified
construction.
BRIEF DESCRIPTION OF THE DRAWING
These and further features, advantages and objects of the present
invention will become more apparent from the following description
when taken in conjunction with the accompanying drawing which
shows, for purposes of illustration only, several embodiments in
accordance with the present invention and wherein:
FIG. 1 is a front view, partly in elevation and partly in section,
of the ice making machine in accordance with the present
invention;
FIG. 2(a) is an enlarged fragmentary perspective view of an ice
forming member which is an essential part of the ice making machine
of the present invention;
FIGS. 2(b) and 2(c) are a front sectional view of FIG. 2(a) and a
side view of a partition mounted on the ice forming member,
respectively;
FIG. 3 is a schematic view of a refrigerant supply circuit in
accordance with the present invention;
FIG. 4 is a schematic view of the electrical control circuit in
accordance with the present invention;
FIGS. 5(a)-(d) are cross sections of the other shaped evaporators
in accordance with the present invention; and
FIG. 6 is a perspective view of another partition in accordance
with the present invention.
DETAILED DESCRIPTION OF THE DRAWING
Referring now to the drawing and, in particular, to FIG. 1, there
is shown an ice making machine having a first compartment 1 and a
second compartment 2. A compressor 3, a condenser (not shown) and
part of the controls are placed in the second compartment 2. An ice
forming member 4, an ice storage vessel 5, and a water distribution
system which includes a water tank 6, a water supply 7, a water
distribution pipe 8 and a sump 9 are located in the first
compartment. The tank 6 is provided with water from a source of
water supply (not shown) through a line 10. The level of water in
the tank 6 is detected by suitable detector means 13 to control the
refrigeration and harvesting cycles which will be described in
greater detail herein below. The water level detector means 13
comprises, for example, three needles 131, 132 and 133 which are
vertically inserted from the top walls of the tank 6 into the water
therein as shown in FIG. 4, and the length of each of the needles
is different from each other. Valve 11 is disposed in the line 10
between the tank 6 and the source of water supply in order to
regulate the quantity of water flowing therethrough.
Pump 12 is placed in the tank 6 to supply water from the tank 6 by
means of the pipe 7 to the water distribution pipe 8 having a
plurality of openings formed at the under side of the pipe so as to
provide a plurality of water streams over the surface of the ice
forming member 4 described herein below. Water from the ice forming
member 4 falls to the sump 9 placed below the member 4. Mesh wire
screen 91 is provided over the sump 9 to permit passage of water
therethrough while preventing passage of the pieces of ice. The
sump 9 has a water outlet for leading water into the tank 6. Thus,
water is continuously circulated in the closed circuit including
the tank 6, the pipe 7, the distribution pipe 8, the ice forming
member 4 and the sump 9.
On a partition 14 between the first and second compartments 1 and
2, there is located an ice storage vessel 5 into which pieces of
ice removed from the ice forming member 4 fall during the
harvesting cycles. The amount of the pieces of ice is detected by a
weight switch 15 generally mounted at the wall of the first
compartment 1. A switching device 51 which is sensitive to
temperature in the ice storage vessel is disposed at a suitable
place, for example, at the position of the inner surface of the
vessel 5. The switching device 51 is connected with control
circuits (described herein after) to effectively prevent melting of
the pieces of ice stored in the vessel 5.
Referring now to FIGS. 2(a) and 2(b), there is shown an ice forming
member 4 in accordance with the present invention. A hollow
pillar-shaped evaporator 41 which is made of a material having high
thermal conductivity such as, for example, steel and constituting
the ice forming member 4 has top and bottom walls, opposed side
walls 413, 414 and end walls 411, 415. One end wall 411 is provided
with an inlet 412 through which refrigerant enters into the
evaporator 41, and the other end wall 415 is provided with an
outlet 416 through which refrigerant is lead out therefrom. Both
side walls 413, 414 are preferably inclined slightly with respect
to a vertical line so that the distance a between the lower ends
thereof is shorter than the distance between the upper ends so that
water is allowed to flow in contact therewith.
On the surfaces of both side walls, a plurality of partitions 42
composed of a material such as, for example, resin having a lower
thermal conductivity than that of the evaporator are mounted by any
suitable bond or mechanical connection so as to be vertically
extended from the top to the bottom of the side walls, and the
partitions are placed apart and parallel with respect to each other
so as to form water stream passages therebetween. The evaporator 41
in accordance with the present invention is attached with side
boards 451 and 452 made of a material such as, for example, a resin
having lower thermal conductivity than that of side walls 413, 414
of the evaporator so as to form parts of the ice forming plates 42
of the evaporator. The side boards 451 are projected upwardly from
the top roof X of the evaporator 41 and are vertically opposed to
each other or vertically inclined to each other as shown in FIGS.
2(b), and 5(a)-(d). Similarly, the side boards 452 are projected
downwardly from the bottom floor Y of the evaporator as shown in
FIGS. 2(b), 5(a) and 5(d). A single side board 452 is also operable
as shown in FIGS. 5(b) and 5(c).
The pieces of ice may be, therefore, firstly formed on the side
walls 413 and 414 of the evaporator 41 and gradually grown toward
and over the resin boards 451 and 452. The side boards 451 and 452
have low thermal conductivity so that they are cooled less in
comparison with the side walls 413, 414 of the evaporator 41.
Accordingly, a portion of the grown pieces of ice on the side
boards 451 and 452 do not firmly cling therewith, so that the
pieces of ice may be easily removed from the ice forming plate
during the harvesting cycles. Each partition 42 is preferably so
designed that the thickness thereof is reduced horizontally from
its contact point with the side walls outwardly as well as
vertically from its top to the bottom as shown in FIG. 2(c). Such a
partition shape effects easy removal of grown pieces of ice from
the surfaces of the side walls during the harvesting.
Roof 43 is provided over the top wall 417 of the evaporator 41 in
order that the water falling from the distribution pipe 8 may be
lead onto the side walls 413, 414 thereof and may uniformly flow in
contact with the surfaces of the side walls. The distribution pipe
8, which is located above the roof 43, is provided with a plurality
of openings through which a water stream may be continuously
supplied to the evaporator during the ice forming cycles. It is
desirable to attach mutually opposed side boards 44 on the top
portions of the partitions 42 and with a small distance C from the
contact portion as shown in FIG. 2(b) in order to prevent
scattering of the water. Located below the ice forming member 4 is
a sump 9 which is provided with a mesh wire screen 91 on the
surface thereof. Water flowing over the outer surfaces of the side
walls of the evaporator 41 falls onto the sump 9 through the screen
91 and returns to the water tank 6.
During the ice forming cycles, the evaporator 41 is supplied with
liquid refrigerant through the inlet 412 so as to be cooled at the
surfaces of the opposed side walls 413, 414 thereof at
substantially a freezing temperature. At the same time, water is
continuously supplied by the pump 12 from the tank 6, through pipe
7, distribution pipe 8 to the ice forming member 4. Therefore,
portions of the water stream flowing between the respective
partitions 42 on the outer surfaces of the side walls 413, 414 of
the evaporator 41 are gradually frozen to finally form separate
pieces of ice. Thus, cooled water not frozen into ice is
continuously recirculated over the ice forming plates. This then
reduces the time required for ice formation. When ice pieces are
sufficiently grown, the period of harvesting cycles is commenced,
wherein the evaporator 41 is provided with heated refrigerant vapor
through the inlet 412, so that the surfaces of the ice forming
plates are heated and the pieces of ice are removed therefrom as
shown by a dotted shape in FIG. 2(b). Controls for the
refrigeration and harvesting cycles are described in greater detail
herein below.
Referring now to FIG. 3, there is schematically shown the
refrigerant supply circuit which includes a compressor 3, an
evaporator 41 and a condenser 20. Refrigerant compressed by the
compressor 3 is supplied to the condenser 20 and than cooled by air
or water. Refrigerant is thus converted from the gaseous state to
the liquid state and is supplied, by way of capillary tube 21, to
the evaporator 41 which is placed in the first compartment 1.
Liquid refrigerant evaporates and absorbs heat from the surrounding
atmosphere therearound in the compartment 1 and is converted into
the gaseous state. Then, the refrigerant returns to the compressor
3. A valve 23 is placed at a downstream position of the refrigerant
in a line 25 from the compressor 3. A heated refrigerant vapor line
26 branches from the valve 23 and terminates upstream of the
evaporator 41 in the line 24 between the evaporator 41 and the
capillary tube 21 so that hot refrigerant bypasses from the
compressor 3 to the evaporator 41. The solenoid valve 23 switches
the refrigerant to bypass either the line 26 or the lines 24 and 25
as well as the condenser 20 and the capillary tube 21. In the
harvesting cycles, the valve 23 is so operated as to provide
refrigerant from the compressor 3 to the evaporator 41 through the
line 26, and in the ice forming cycles, to provide refrigerant
through the condenser 20 and the capillary tube 21.
FIG. 4 shows an electrical circuit for controlling the
above-mentioned water distribution system, the refrigerant supply
circuit and the other equipment associated with the ice making
machine of the present invention. The compressor motor unit 31 is
supplied with operating power from an A.C. power source 50 through
a temperature control, that is the switching device 51 which is
disposed at the suitable place in the ice storage vessel 5 to
detect temperatures therein. If temperatures in the ice storage
vessel 5 exceed the freezing point of water, the controller 51
becomes operative and switches to the "on" position, while it
switches to the "off" position at temperatures below the freezing
point of water. An alternating current from the power source 50 is
also supplied to the primary winding of a transformer 52 by means
of weight switch 15 located on the inner wall of the first
compartment 1. The weight switch 15 is maintained in its closed
state until a sufficient amount of ice has been stored in the ice
storage vessel 5 so as to exceed a certain predetermined weight.
When the weight of the ice stored is over a predetermined value,
for example, several kilograms, the weight switch 15 opens the
circuit and thus the ice making function is stopped.
An induced voltage appears across the secondary winding of the
transformer 52 and it is applied to a pair of opposed diagonal
nodes F and G of a full wave rectifying diode bridge circuit 53
through the water level detector 54 in the tank 6 so that a
rectified output representative of the A.C. voltage applied is
obtained between the other nodes. The water level detector 54 has
three needles 131, 132 and 133 vertically disposed from the inside
wall of the tank into the water therein. The detection heights of
the respective needles are different from each other. A first
detecting needle 131, the longest of the three, is connected with
one terminal of a secondary winding of the transformer 52. A third
detecting needle 133, the shortest of the three is connected with
one node G of the diode bridge circuit 53. Between the second
detecting needle 132 having medium length and the third detecting
needle 133, a relay contact 551 is inserted which conducts on-off
operations in response to current flowing through a relay coil 552.
Between the diagonal nodes H and I of the bridge are connected the
parallel circuit of a smoothing capacitor 56 and the relay coil
552.
A change-over switch 57 is also operated in accordance with current
flowing through the relay coil 552. In the non-energized period of
the relay coil 552, the switch 57 is closed to a contact A, so that
A.C. current provided from the A.C. power supply 50 can flow
through an exciting coil 231 connected in series therewith. Under
such conditions, the valve 23 located at the connecting point of
the refrigerant lines 25 and 26 is operated to pass heated
refrigerant vapor from the compressor 3 to the evaporator 41
through the line 26. When the relay coil 552 is energized with D.C.
current from the bridge circuit 53, the change-over switch 57 is
closed to contact B so that A.C. current from the power supply 50
can flow through a motor unit 121 for pump 12 shown in FIG. 1. An
exciting coil 111 for controlling the water supply valve 11 and a
switch of a temperature controller 58 placed on the evaporator 41
are serially connected with the motor unit 121. When the exciting
coil 111 is supplied with A.C. current, the valve 11 is opened to
supply the water flow source to the tank 6. The temperature
controller 58 acts to perform on-off operations according to
whether the temperature at the surface of the evaporator 41 is or
is not over 20.degree. C.
The operation of the above-mentioned ice making machine in
accordance with the present invention will now be considered. In an
initial condition, the temperature controller 51 is in its
on-position while the temperature in the first compartment 1 as
well as ice storage vessel 5 is above the freezing point of water.
The weight switch 15 is closed since no piece of ice is stored in
the vessel 5. The switch 551 is opened and the change-over switch
is closed to the contact A for the reason that the relay coil 552
is not excited until the water level in the tank reaches the
extreme point of the shortest needle 133.
Under such an initial condition, the change-over valve 23 connects
the compressor 3 to the line 24. Therefore, compressed refrigerant
vapor from the compressor 3 is directly supplied to the evaporator
through the line 26. The temperature at the surface of the
evaporator 41 gradually rises, and when the temperature exceeds the
predetermined value, for example 20.degree. C., the temperature
controller 58 disposed on the evaporator 41 turns into the
on-position. Accordingly, current supplied from the power supply 50
flows through the exciting coil 111, so that the valve 11 is opened
to permit passage of the water from the water supply to the tank 6.
Although the exciting current also flows through the motor unit
121, the power supplied thereto is too small to drive the motor
unit, because the power from the source 50 is mostly applied to the
exciting coil 111 having a larger impedance compared to that of the
armature winding of the motor unit 121.
When the water level in the tank 6 is increased to reach the
extreme point of the third needle 133, the passage between the
terminals C and E is electrically conducted through water in the
tank so that the induced voltage across the secondary winding of
the transformer 52 may be applied between the nodes F and G of the
diode bridge circuit 53. The rectified voltage appearing between
the nodes H and I is smoothed by the capacitor 56 and then applied
across the relay coil 552. Accordingly, the switch 551 is closed to
maintain the application of the induced voltage to the bridge
circuit until the water level is over the second needle point and
the change-over switch is closed on the contact B.
When the change-over operation of the switch 57 is conducted from
the contact A to B, valve 23 operates to close the refrigerant line
26, thereby preventing passage of heated refrigerant vapor
therethrough and opening the refrigerant line 25 between the
compressor 3 and the condenser 20. The heated high pressure
refrigerant vapor from the compressor 3 is, therefore, condensed
and liquified by the condenser 20 and then its pressure is reduced
by the capillary tube 21 and is thereafter provided to the
evaporator 41. At the same time, the motor unit 121 commences its
rotation by the application thereto of operational current from the
power source 50 through the change-over switch 57, so that the pump
12 begins to supply water from the tank 6 onto the surfaces of the
ice forming plate of the evaporator 41. On the other hand, since
the series connected circuit of the exciting coil 111 and the
temperature controller 58 is short-circuited by the change-over
switch 57, the exciting coil 111 cannot be activated. Thus, water
supply from the supply source to the tank 6 may be
discontinued.
Water carried from the tank 6 in the distribution pipe 8 is
discharged through the openings thereof onto the roof 43 of the
evaporator 41 and then flows in contact with the outer surfaces of
the ice forming plates on which the partitions 42 are vertically
disposed so as to form channels for the water streams. Portions of
water flowing over the surfaces of the ice forming plates of the
evaporator 41 are frozen to form pieces of ice since the evaporator
41 is cooled substantially below the freezing point of water by the
refrigerant supplied thereinto. Cooled water not formed into ice
falls in the sump 9 and returns to the tank 6 and is recirculated
over the ice forming plates to increase the amount of ice formed
thereon.
When the water level in the tank 6 becomes lower than the position
of the extreme point of the second needle 132, the electrical
passage between the terminals C and D is disconnected so as to
discontinue the supply of A.C. current from the transformer 52 to
the diode bridge circuit 53. Thus, the relay coil 552 terminates
its on-position and the switch 551 returns to its on-position and
the change-over switch 57 is closed on the contact A to provide
A.C. current from the power source 50 to the exciting coil 231 for
the valve 23. Under such conditions, the motor unit 121 for the
pump 12 is released from its energized state, so that the supply of
water from the tank to the ice forming plates is discontinued.
At the same time, the change-over valve 23 acts to connect the
compressor 3 to the evaporator 41 through the line 26, while
disconnecting the passage between the compressor 3 and the
condenser 20. Accordingly, the evaporator 41 is now supplied with
heated refrigerant vapor to remove pieces of ice from the outer
surfaces of the ice forming plates. The pieces of ice fall into the
ice storage vessel 5 as shown by the dotted line in FIG. 2(b). Once
all the pieces of ice have been removed from the ice forming
plates, the temperature of the surfaces thereof is gradually
raised. If its temperature becomes higher than 20.degree. C., the
temperature controller switchs into the on-position to energize the
exciting coil 111 for the valve 11 for again supplying water from
the supply source to the tank 6.
By repeating the above-mentioned operations of the ice forming and
harvesting cycles, the amount of the pieces of ice stored in the
ice storage vessel 5 is gradually increased. When the weight of the
stored pieces of ice exceeds a predetermined value, the weight
switch 15 disposed on the outer surface of the first compartment 1
operates to open the control circuit in order that the ice forming
function may be discontinued thereafter. To prevent the pieces of
ice stored in the ice storage vessel 5 from melting, the
temperature controller 51 switches to its on-position to drive the
compressor motor 31 whenever the temperature in the ice storage
vessel exceeds the freezing point of water. Although here the
change-over switch is closed on the contact A, the solenoid valve
23 may not be energized since the weight switch 15 is opened so as
not to provide A.C. power thereto. The refrigerant on the
compressor 3 is, therefore, transferred through the condenser 20 to
the evaporator 41. Thus, the surface of the evaporator 41 is not
provided with water and the evaporator 41 refrigerates the
surrounding atmosphere. Therefore, temperatures in the first
compartment 1 may be maintained lower than the freezing point of
water so as to prevent the melting of the pieces of ice stored in
the vessel 5.
The above-described ice making machine is so constructed that the
side walls of the evaporator 41 are used as the ice forming plates
and water from the tank 6 is directly supplied thereon, whereby the
efficiency of ice forming is very much higher than that of
conventional devices. Furthermore, the present invention directly
produces pieces of ice without producing first a slab of ice, and
therefore, it does not require any cutting devices. Consequently,
the machine of the present invention is of low cost, low power
consumption, and of compact configuration.
While we have shown and described one embodiment in accordance with
the present invention, it is to be clearly understood that the same
is susceptible of numerous changes and modifications as will be
apparent to one skilled in the art. For example, while the
evaporator 41 as described above is of hollow pillar-shape,
differently shaped evaporators shown cross-sectionally in FIGS.
5(a)-(d) may be used for the ice making machine in accordance with
the spirit of the present invention. Among these modifications,
however, it is necessary that the uppermost distance be between the
side walls 413 and 414 of the evaporator 41 is longer than the
lowermost distance A thereof. Furthermore, the partition 42
disposed on the ice forming plate can be also modified to various
shapes, one of which is illustrated in FIG. 6. This partition is
designed so that the uppermost extension E is longer than the
lowermost extension D. The above relations between the distances A
and B and between the extensions D and E are effective for the easy
removal of the grown pieces of ice on the ice forming plate during
the harvesting cycles. Therefore, we do not wish to be limited to
the details shown and described herein but intend to cover all such
changes and modifications encompassed by the scope of the present
invention.
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