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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a box type fresh food storing device for
storing fresh foods such as vegetables, fruits, cereals, meats, eggs, milk
products and the like. The device of the present invention is for use in
the form of a box type fresh food storing unit installed on the floors of
homes, liquor stores and supermarkets.
2. Discussion of the Related Art
A fresh food storing device for storing in a fresh state vegetables,
fruits, cereals and the like is disclosed in Japanese Patent Publication
No. Sho-601200, in which a gas generating unit is installed for producing
carbon dioxide gas by burning a high carbon purity solid fuel or liquid
fuel. Thus the produced gas containing carbon dioxide is supplied to the
fresh food storing volume in order to inhibit the respiration of the fresh
foods
Another fresh food storing device is disclosed in Japanese Patent
Publication No. Sho-59-14749 which describes a large scale storing plant,
and in which a nitrogen-rich gas is supplied to the storing volume.
In the device disclosed by Japanese Patent Publication No. Sho-60-1200,
combustion is used and therefore it is inconvenient to use in homes and
stores, because there is the possibility of fire and toxic effects due to
the existence of carbon monoxide, thereby making the device undesirable in
view of safety.
Meanwhile the device disclosed by Japanese Patent Publication No.
Sho-59-14749 is not applicable to homes and small stores, but is for use
in large storage plants.
SUMMARY OF THE INVENTION
The present invention is intended to overcome the disadvantages and the
limitations of the devices of the prior art.
Therefore it is an object of the present invention to provide a fresh food
storing device which is suitably installed on the floors of homes and
stores.
For achieving the above and other objects, the present invention comprises
a storing volume for storing fresh foods, a box surrounding the storing
volume and containing a detecting means for detecting the temperature of
the gas in the storing volume, a cooling unit for cooling the interior of
the storing volume formed within the box, a nitrogen-rich gas supplying
device for supplying a nitrogen-rich gas into the storing volume formed
within the box, and a controller for controlling the cooling unit in order
to regulate the temperature of the interior of the storing volume in
response to a signal from the temperature detecting means, and for
controlling the nitrogen-rich gas supplying device to regulate the content
of the nitrogen gas within the storing volume in response to the detection
of the contents of the gases within the storing volume.
The storing box of the present invention can be made in the form of a
longitudinally long type, a laterally long type, one adopted to a system
kitchen, one buried into a wall, or one adapted to cars. The shape of the
box can be properly determined and, for example in the case where it is
installed in a room, it can be made of the longitudinally long type in
order to save space. The material of the box can be a metal or synthetic
resin, and is not subjected to any special limitation. The walls of the
storing volume can be wrapped with a heat insulating material. The shape
of the storing volume, for example, can be made longitudinally long, and
the box can be provided with a pressure regulating means. In the case
where such a pressure regulating means is used, the interior of the
storing volume is maintained in a sealed state, and if the pressure of the
interior of the storing volume is raised to an excessive level, the
pressure regulating means is activated to discharge gas out of the storing
volume. Thus, as the pressure regulating means is activated only when an
excessive level of gas pressure is reached, the leaking of gas from the
storing volume can be prevented. The pressure regulating means may, for
example, comprise a discharge opening leading from the interior of the
storing volume to the outside, and an opening/closing member which
normally closes the storing volume and opens when the gas pressure of the
storing volume reaches a predetermined level. The bottom of the box can be
provided with supporting legs.
As to the temperature detecting means for detecting the temperature of the
interior of the storing room, a known type of temperature sensor, for
example, a shape memory alloy, can be used. It is desirable to provide the
box with an oxygen detecting means for detecting the oxygen concentration
within the storing volume. As the oxygen detecting means, a known type of
oxygen sensor can be used. In response to oxygen detection by the oxygen
detecting means, the controller will activate the nitrogen-rich gas
supplying device for supplying the nitrogen-rich gas into the storing
volume. The controller may be composed of logic circuits in microcomputer,
or can be composed of hard wired logic circuits. The controller also can
intermittently activate the nitrogen-rich gas supplying device by
outputting the driving signals as time passes. In this case, an external
timer, that is an internal timer of a CPU, can be used to calculate the
passing of time so that if the predetermined time is elapsed, the
nitrogen-rich gas supplying device will be activated.
The box can also be constituted such that an oxygen supplying device is
provided for supplying oxygen gas or a gas containing oxygen gas into the
storing volume. As the oxygen supplying device, a compressor for supplying
the external air into the storing volume can be used. When the oxygen
detecting means indicates an oxygen content level lower than the
predetermined level, the controller will activate the oxygen supplying
device, while if the oxygen detecting means indicates an oxygen content
level higher than the predetermined level, the controller will activate
the nitrogen-rich gas supplying device so that a nitrogen containing gas
can be supplied into the storing room. It is also desirable to provide a
circulating device for circulating the gas in the interior of the storing
volume and, as the circulating device, a fan can be used. It is of course
possible that the circulating device is operated all the time, is operated
intermittently at predetermined intervals, or is operated each time the
nitrogen-rich gas is supplied to the storing volume by the nitrogen-rich
gas supplying device. If the gas of the storing volume is curculated, the
biased concentration of the gas within the storing volume can be reduced,
and the fresh foods can be kept in a uniformly distributed gas, thereby
preventing the rotting of the foods. The position of the circulating
device can be properly determined according to need.
As the nitrogen supplying device, a nitrogen concentrating device can be
used in which external air is used to concentrate nitrogen gas. The
position of the nitrogen supplying device to be installed in the box is
not limited and, for example, it can be disposed at the rear of the
storing volume or at the bottom of the storing volume. In a preferred
embodiment, the nitrogen-rich gas supplying device comprises a separating
tank having an oxygen absorbing portion and a compressor for supplying
compressed external air into the separating tank. In the oxygen absorbing
portion, an oxygen absorbing agent such as active carbon, zeolite and the
like can be used. The separating tank can be designed as a vertical
longitudinally long type for minimizing the occupying space. In the case
where a plurality of separating tanks are used, they can be disposed in
parallel either along the depth direction of the box or along the lateral
direction of the box. In the case where a plurality of the separating
tanks are disposed parallelly along the lateral direction of the box, it
is advantageous to make the depth dimension of the boxes as small as
possible. In some special cases, the nitrogen-rich gas supplying device
can be provided with a liquid nitrogen tank in order to supply the
nitrogen in evaporated gas form, or can be provided with a nitrogen bomb.
As will be described below, the fresh food storing device of the present
invention can have a separating wall within the storing volume for
providing partitions within the storing volume, in order to form a rear
wall and a space. In such cases, the separating wall can be provided with
a first opening and a second opening, and the evaporation mechanism of the
cooling system can be disposed between the first and second openings to
make it positioned in the space. Further, the outlet of the nitrogen-rich
gas supplying device can be disposed between the evaporation mechanism and
the second opening, and the circulating device can be disposed near the
first opening. Further, a by-pass path connected to the storing room can
be installed, and an ethylene remover can be installed at a position on
the by-pass. In this case, the gas within the storing volume is circulated
between the by-pass path and the storing volume by means of a pump driven
by an actuator. Through such a circulation, ethylene can be removed by
means of an ethylene removing member. As the material of the ethylene
removing member there can be used a divalently bonded hydrocarbon rubber
or resin, or hydrocarbon rubber or resin, or hydrocarbons without divalent
bonding. For example, there may be used natural rubbers, polyethylene,
polypropylene, active carbon, or potassium permanganate. The form of the
ethylene removing member can be powder or foamed solid.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and other advantages of the present invention will become
more apparent by describing the preferred embodiments of the present
invention with reference to the attached drawings in which:
FIG. 1 is an exemplary view of the internal structure of the fresh food
storing device according to an embodiment of the present invention;
FIG. 2 is a perspective view of the resin food storing device of FIG. 1
with the door closed;
FIG. 3 is a perspective view of the fresh food storing device of FIG. 1
with the door open;
FIG. 4 is a flow chart showing the main routine operated by the CPU;
FIG. 5 is a flow chart showing the temperature regulating subroutine;
FIG. 6, is a flow chart showing the regulation of the nitrogen-rich gas
supplying;
FIG. 7 is a flow chart showing the humidity regulating subroutine;
FIG. 8 is a flow chart showing the ethylene regulating subroutine; and
FIG. 9 is an exemplary view of another embodiment of the present invention
showing the internal structure of the fresh food storing device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The first embodiment of the present invention will be described with
reference to FIGS. 1 to 8. FIG. 1 shows an exemplary view of the internal
constitution of the fresh foods storing device of the first embodiment,
while FIGS. 2 and 3 respectively show perspective views of the device of
the first embodiment with the door closed and with the door open. As shown
in FIGS. 2 and 3, the box 1 has a vertically long shape for minimizing
occupied space, and a storing volume 2 is formed within the box 1. The
storing volume is partitioned into four vertically separated compartments:
a first storing compartment 3, a second storing compartment 4, a third
storing compartment 5, and a fourth storing compartment 6. The first,
second and third storing compartments 3, 4, 5 are respectively
opened/closed by means of first, second and third pivotal doors 7, 8, 9,
while the further storing compartment 6 is opened/closed by means of a
drawer type fourth door 10. The bottom of the box 1 is provided with
supporting legs (not shown) There is installed a shelf 11 on the inside of
the first door 7, and there are installed shelves 12, 13 on the inside of
the third door 9. There are installed shelves 15, 16 within the third
storing compartment 5.
Now the internal constitution of the fresh food storing device will be
described with reference to FIG. 1. A separating wall 18 is disposed for
keeping a certain gap between food stored in the device and a rear wall 17
which is one of the walls defining the storing volume 2. The separating
wall 18 is provided with a first or upper opening 19 and with a second or
lower opening 20. A cooling mechanism 21 is installed on the real wall 17
and at the bottom of the storing volume 2. The cooling mechanism 21
includes tubes 26 connecting the evaporation mechanism 23 disposed in the
space 22 between the rear wall 17 and the separating wall 18 of the
storing volume 2 to a condensating unit 28 disposed outside the storing
volume 2 and to a compressor 24 and an expansion valve 25.
The compressor 24 is provided with a motor 27, and the motor 27 of the
compressor 24 is installed at the bottom of the box 1. If the compressor
24 is activated, as in an ordinary cooling cycle, the cooling medium in
the gas phase is compressed by the compressor 24 into a highly compressed
state having a high temperature and then is sent to the condensating unit
28 where the compressed gas having a high pressure and a high temperature
is condensed into a liquid. Then this condensed cooling medium is
transformed into a fog having a low pressure and a low temperature to be
introduced into the evaporation mechanism 23 where the cooling medium
draws heat from the surface of the evaporation mechanism 23, thereby
effecting heat absorption. Thus, the gas within the storing volume 2,
especially the gas within the space 22 between the rear wall 17 and the
separating wall 18, drops to a low temperature, for example to 2 to
5.degree. C., and is maintained in that temperature range. A nitrogen-rich
gas supplying device 30 is disposed within the box 1, and this
nitrogen-rich gas supplying device 30 comprises a first separating tank 31
having absorbing agent such as an active carbon, a second separating tank
32 also having an absorbing agent such as an active carbon, a hollow
nitrogen buffer tank 33, a compressor 34, a motor 35 for the compressor
34, a vacuum pump 36, and a motor 37 for the vacuum pump 36. The first
separating tank 31, the second separating tank 32 and the nitrogen buffer
tank 33 have an elongate shape respectively and are disposed in the
vertical direction respectively. Further they are parallelly disposed at
nearby positions to each other, and therefore they conveniently fit into
the longitudinally long shape of the box 1, thereby contributing to the
compactness of the box 1. Although they appear separated in the horizontal
direction in FIG. 1, they are actually separated in the depth direction,
i.e., into the plane of FIG. 1.
In this embodiment, the first separating tank 31 and the second separating
tank 32 have a longitudinally long shape and therefore, compared with the
case of a laterally long shape, they are advantageous in minimizing the
gaps between the absorbing agent filled in the first separating tank 31
and the second separating tank 32 and the surface of the wall surrounding
the first separating tank 31 and the second separating tank 32.
Accordingly the absorbing agent can absorb the oxygen in the air in a more
sure manner. The compressor 34, the motor 35 for the compressor, the
vacuum pump 36, an the motor 37 for the vacuum pump are heavy, and
therefore they are disposed near the bottom of the box 1 in order to
provide a lower center of gravity. The first separating tank 31 and the
second separating tank 32 connect to the outside of the box 1 through a
concentrating tube 39 and a regenerating tube 40. An inlet 41 which is the
leading end of the concentrating tube 39, and an outlet 42 which is the
leading end of the regenerating tube 40, are disposed below the bottom of
the box 1. Therefore, in the case where walls of the building and other
structures are closely adjacent the side of the fresh food storing device,
external air can be sucked in through the inlet 41 of the tube 39, and the
gas can be discharged from the first separating tank 31 and the second
separating tank 32 through the outlet 42 of the tube 40 regardless of the
existence of such walls and other structures.
The tube 39 is connected to a valve 43, a valve 44, a safety valve 45, the
compressor 34 and an air filter 46. The air filter 46 is for cleaning the
incoming air, and is detachably installed for cleaning or replacement. The
tube 40 has a valve 47, a valve 48, a valve 49 and the vacuum pump 36. The
tube 40 is also connected to a tube 50, and an outlet 51 which is the
leading end of the tube 50 is disposed below the bottom of the box 1. A
check valve 52 is also installed on the tube 50. The first separating tank
31 and the second separating tank 32 are connected to the inlet of the
nitrogen buffer tank 33 through a tube 54 which is in turn connected
through a valve 55, a valve 56 and a valve 57. The outlet of the nitrogen
buffer tank 33 is extended to the storing volume 2 through a tube 59, and
the outlet 60 for the nitrogen-rich gas which is the leading end of the
tube 59 reaches the interior of the storing volume 2. The tube 59 has a
valve 61, a pressure reducing valve 62 and a flow regulation valve 63, and
the tube 39 is connected to a tube 65, and to an air outlet 66 which is
the leading end of the tube 65 reaching to the interior of the storing
volume 2.
The tube 65 has a valve 67, a pressure reducing valve 68 and a flow
regulation valve 69. The valves disposed at the inlet side of the first
separating tank 31, such as the valve 67, the valve 43, the valve 44, the
valve 47, the valve 48 and the valve 49 are connected to a controller 70.
the valves disposed at the outlet side of the first separating tank 31,
such as the valve 55, the valve 56, the valve 57 and the valve 61 are also
connected to the controller 70. In this embodiment, the controller 70
installed on the box 1 is constituted by a microcomputer having an input
interface, an output interface, a CPU and a memory.
If an nitrogen concentrating process is to be carried out in the first
separating tank 31, first the valve 47 is closed, and then the compressor
34 is driven by means of the motor 35 with the valve 43 and the valve 55
put in an activate state. Then the external air will reach the valve 43
through the air filter 46 and the tube 39 for the air to be compressed and
filled into the first separating tank 31. Then due to the difference
between the absorption rates of nitrogen and oxygen in the separating
tank, most of the oxygen is absorbed by the absorbing agent installed
within the first separating tank 31, thereby carrying out the nitrogen
concentrating process and forming a nitrogen-rich gas. Then the
nitrogen-rich gas is delivered through the valve 55 and the valve 57 to
the nitrogen buffer tank where the gas is subjected to lowering of its
pressure. The nitrogen-rich gas is then delivered through the valve 61 to
the pressure reducing valve 62 to be subjected to a further reduction of
pressure and then is blown into the storing volume 2 through the flow
regulation valve 63 and the nitrogen-rich gas outlet 60 which is the
leading end of the tube 59.
If a regeneration process is to be carried out in the first separating tank
31, the valves 55, 43, 49 are closed as the first step, and then the valve
47 is opened so that the gas within the first separating tank 31 can be
naturally discharged to the outside through the valve 47, the tube 40, the
check valve 52 and the outlet 51. To carry out the second step of the
regenerating process, the valve 49 is opened and the vacuum pump 42 is
driven by means of the motor 37. then the gas within the first separating
tank 31 is sucked off to be forcibly discharged through the outlet 42,
thereby making the internal pressure of the first separating tank 31 drop
to below one atmosphere in pressure. As a result of such suction, the
absorbing agent installed within the first separating tank 31 is
regenerated so that it can perform the oxygen absorbing function again.
If the nitrogen concentrating process is to be carried out in the second
separating tank 32, first the valve 43 for the first separating tank 31 is
closed, and then the compressor 34 is driven with the valve 44 open. Then,
as described above, air is delivered under pressure to the second
separating tank 32 through the air filter 46, the tube 39 an the valve 44.
Then most of the oxygen is absorbed by the absorbing agent installed
within the second separating tank 32, thereby carrying out the nitrogen
concentrating process for producing a nitrogen-rich gas. This
nitrogen-rich gas is delivered to the nitrogen buffer tank 33 through the
valve 56 and the valve 57, to be subjected to lowering of pressure there.
This gas is delivered through the valve 62 to the pressure reducing valve
62 to be subjected to a further reduction of pressure, and then is blown
into the storing volume 8 through the flow regulation valve 63 and the
nitrogen-rich gas outlet 60 which is the leading end of the tube 59.
If the regenerating process is to be carried out in the second separating
tank 32, as the first step the valves 44, 56, 49 are closed and the valve
48 is opened to discharge the gas of the second separating tank 32 to the
outside through the valve 48, the regeneration tube 40, the check valve 52
and the outlet 51. To carry out the second step of the regeneration
process, the valve 49 is opened and the vacuum pump 36 is driven by means
of the motor 37, so that the gas within the second separating tank 32 may
be forcibly sucked away, thereby making the internal pressure of the
second separating tank 32 drop to below one atmosphere in pressure. As a
result of such a suction, the absorbing agent installed within the second
separating tank 32 is regenerated, so that it is capable of absorbing the
oxygen again. It should be noted that when a nitrogen concentrating
process is being carried out in the first separating tank 31, a
regenerating process is carried out in the second separating tank 32. On
the contrary, if a nitrogen concentrating process is being carried out in
the second separating tank 32, a regenerating process is carried out in
the first separating tank 31.
Within the storing volume 2, there are disposed sensors such a thermostat
71 as the temperature detecting means, a humidity sensor 72 as the
humidity detecting means, a carbon dioxide sensor 73 as the carbon dioxide
detecting means, an ethylene sensor 74 as the ethylene detecting means,
and an oxygen sensor 75 as the oxygen detecting means. The thermostat 71
is constituted such that its predetermined temperature can be adjusted
arbitrarily. The thermostat 71, the humidity sensor 72, the carbon dioxide
sensor 73, the ethylene sensor 74, the oxygen sensor 75 and the motor 27
for driving the compressor of the cooling mechanism 21 are connected to
the controller 70. If it is determined, as the result of the detection by
the oxygen sensor 75, that the oxygen concentration within the storing
volume 2 is too low, then the valve 67 is opened, the valves 43, 44 are
closed at the same time, and the motor 35 is activated to drive the
compressor 34, so that the external air sucked in through the inlet 41 can
be blown to the air outlet 66 through the tube 65, the pressure reducing
valve 68 and the flow regulating valve 69, thereby ultimately filling the
air into the storing volume 2 through the air outlet 66.
A lighting lamp 76 is installed within the storing volume 2, so that the
visible light is shed on the fresh food stored therein. This lighting lamp
76 is lighted for a predetermined time by means of a timer 81. If the
lighting lamp 76 is lighted, the light therefrom causes photosynthesis in
the stored fresh foods. When such photosynthesis is carried out, oxygen is
generated and therefore the oxygen concentration within the storing volume
2 is increased, resulting in that the respiration of the fresh foods can
be reduced, inhibited or stopped, thereby contributing to the long term
storing of the foods.
A humidifier 77 is installed at an upper position of the storing volume,
and this humidifier 77 is for humidifying the storing volume when the
humidity within the storing volume drops below the predetermined level.
The water reservoir of the humidifier is detachably attached for filling
with water. The main reason why the humidifier 77 is installed at an upper
position of the storing volume is for preventing the circulation of the
humidity state, and for making the moisture generated from the humidifier
77 descend toward the lower portion of the storing volume.
A fan 78, serving as a gas circulator , is installed at an upper position
of the storing volume, the fan 78 facing the upper opening 19. Therefore,
if the fan 78 is driven, the gas in the space 22 between the separating
wall 18 and the rear wall 17 is sucked away, thereby forming a flow of gas
through the upper opening 19 end in the direction of the arrow W.
Accordingly, a uniformity of gas concentration, temperature and humidity
within the storing volume can be realized. This makes it possible to
arbitrarily choose the positions of the thermostat 71, the oxygen sensor
75, the humidity sensor 72, the carbon dioxide sensor 73, and the ethylene
sensor 74 within the storing volume 2. The lighting lamp 76, the
humidifier 77 and the fan 78 are connected to the controller 70. The
storing volume 2 is also provided with an internal lamp 79 which is
lighted upon opening of the door, due to the function of a door switch 80.
The nitrogen-rich gas delivered from the nitrogenrich gas outlet 60 into
the storing volume 2 is the gas formed by concentrating the nitrogen from
the external air, while the air delivered fro the air outlet 66 into the
storing volume 2 is the external air. Therefore, the nitrogen-rich gas and
the air blown into the storing volume have a higher temperature than the
gas which has been kept within the storing volume 2. For this reason,
there arises the need for efficiently cooling the nitrogen-rich gas and
the air which are being introduced into the storing volume. For this
purpose, the nitrogen-rich gas outlet 60 as the leading end of the tube 59
and the air outlet 66 as the leading end of the tube 65 are disposed
between the evaporation mechanism 23 and the lower opening 20, and
therefore, most of the nitrogen-rich gas and the air having a high
temperature and blown into the storing volume through the nitrogen-rich
gas outlet 60 and the air outlet 66 respectively are sucked upwardly by
the circulating action of the fan 78, are deprived of their heat by the
evaporation mechanism 23, and come downwardly while riding the flow of gas
from the upper opening 19, thus being circulated within the storing
volume. Accordingly, the nitrogen-rich gas and the air blown into the
storing volume 2 through the nitrogen-rich gas outlet 60 and the air
outlet 66 respectively are efficiently and effectively cooled.
A pressure regulating means 83 is installed at a lower position of the
storing volume 2, and this pressure regulating means 83 comprises a
discharge hole 84 reaching the outside of the storing volume 2, a
container 85 connected to the discharge hole 84, and a tube 86 inserted
into the container 85. The container 85 stores water. If the pressure
within the storing volume 2 drops below the predetermined level, the water
level within the container 85 is positioned higher than the lower end of
the tube 86, and therefore, the leaking of the gas from the storing volume
to the outside can be prevented, as well as preventing the intrusion of
the external air into the storing volume through the discharge hole 84. On
the other hand, if the pressure within the storing volume is raised due to
the fact that the nitrogen-rich gas is introduced through that
nitrogen-rich gas outlet 60 during the actuation of the nitrogen supplying
device, or due to the fact that the air is introduced through the air
outlet 66, then the water level falls below the lower end of the tube 86
due to the pressure acting on the water surface within the container 95,
and therefore the tube 86 and the discharge hole 84 will together form a
through passage. Accordingly, the gas within the storing volume 2 is
naturally discharged through the tube 80 and the discharge hole 84.
Further, in order to assure safety, the box 1 is provided with a safety
valve 87 which is activated when the pressure within the storing volume is
excessively raised due to a malfunction of the pressure regulating means
83, in order to discharge the excessive gas out of the storing volume 2.
The box 1 is provided with a by-pass path 90 having an outlet 89 and an
inlet 88 which is open to the interior of the storing volume 2. At an
intermediate position of the by-pass path 90, there is provided an
attachment means 91 external to the storing volume for detachably
installing an ethylene removing member 92 which is composed of either a
chemical absorbing agent such as potassium permanganate or a physical
absorbing agent such as an active carbon. Further, the by-pass path is
provided with a pump 93 toward the inlet side from the attachment means
91, and this pump 93 is driven by a motor 94, which is in turn connected
to the controller 70. If the motor 94 is activated to drive the pump 93,
the gas within the storing volume 2 is sucked into the by-pass path 90
through the inlet 88 in order to flow through the ethylene removing member
92, thereby removing the ethylene contained in the nitrogen-rich gas. The
nitrogen-rich gas after removal of the ethylene returns through he outlet
89 into the storing volume 2.
FIG. 4 is a flow chart showing the main routine of the CPU constituting the
controller 70. A shown in FIG. 4, an initial state is set up by connecting
the power source at the step S1. Then the internal timer of the CPU is
started at the step S2 for determining the length of one routine; input
signals from the different sensors are received at the step S3; the
temperature regulating subroutine is operated at the step S4; the nitrogen
supply regulating subroutine is operated at the step S5; the temperature
regulation subroutine is operated in step S6; the ethylene regulating
subroutine is operated at the step S7; the other subroutines are
sequentially operated at the step S8; a controlling signal is outputted at
the step S9; and at the step S10, the operation returns to the step S2
after waiting for the termination of the internal timer.
FIG. 5 is a flow chart showing the temperature regulating subroutine. As
shown in FIG. 5, a judgement is made at the step S400 as to whether the
temperature within the storing volume is at the reference temperature (for
example 5.degree. C.) or not, and if the actual temperature exceeds the
reference temperature, the motor 27 for the compressor 24 of the cooling
mechanism 21 is activated at the step S402, and then, the operation is
returned to the main routine. If the result of the judgement at the step
S400 shows that the temperature within the storing volume is below the
reference temperature, the operation is transferred to the step S404 where
a judgement is made as to whether the actual temperature corresponds to
the second reference temperature (for example, 2.degree. C.). If the
actual temperature is found to be below the second reference temperature,
then the motor 27 for the compressor 24 of the cooling mechanism 21 is
turned off at the step S406. If the temperature within the storing volume
exceeds the second reference temperature, the existing state is left
without taking any action. As a result of the operation based on this flow
chart, the temperature within the storing volume is maintained between the
first reference temperature and the second reference temperature.
FIG. 6 is a flow chart showing the nitrogen regulating subroutine. The flag
A used in this chart is a conversion flag for the first separating tank 31
and the second separating tank 32, the timer N1 is for regulating the
operation time of the first separating tank 31, and the timer N2 is for
regulating the operation time of the second separating tank 32. That is,
the flag A is set to "0" when the nitrogen concentrating process is
carried out in the first separating tank 31 and at the same time the
regeneration process for the absorbing agent is carried out in the second
separating tank 32. On the other hand, the flag A is set to 1 when the
nitrogen concentrating process is carried out in the second separating
tank 32 and at the same time the regeneration process for the absorbing
agent is carried out in the first separating tank 31.
As shown in FIG. 6, a judgement is made at the step S500 as to whether the
oxygen concentration within the storing volume 2 is above the reference
value (for example, 10%). If it is found that the oxygen concentration
within the storing volume 2 is above the reference value, then the motor
35 for the compressor 34 is turned on at the step S502 in order to
activate the nitrogen rich gas supplying device 30. Then a judgement is
made at the step S504 as to whether the flag A is at "1" or not. If the
flag A is at "0", then the valve 43 is opened and the valves 44, 67 are
closed so that the nitrogen concentrating process can be carried out in
the first separating tank 31. Then the timer N1 is incremented at the step
S508, and the judgement is made at the step S510 as to whether the timer
N1 is timeover. If it is timeover, the flag A is set to "0" at the step
S512, and the function is returned to the main routine. If the result of
the judgement at the step S510 indicates that the timer is not timeover,
it means that the nitrogen concentrating process is being carried out in
the second separating tank 32, and therefore the function is returned to
the main routine.
If the result of the judgement at the step S500 indicates that the oxygen
concentration is below the first reference value (for example, 10%), then
the function is transferred tot he step S520 where a judgement is made as
to whether the oxygen concentration is below the second reference value
(for example, 1%). If it is found that the oxygen concentration is below
the second reference value, it means that the storing volume 2 is in a
state of deficiency of oxygen, and therefore the function is transferred
to the step S522 where the valve 67 is opened, the valves 43, 44 are
closed, and the motor 35 is turned on to drive the compressor for
introducing the air into the storing volume through the air outlet 66.
If the result of the judgement at the step S520 indicates that the oxygen
concentration exceeds the second reference value, it means that the oxygen
concentration within the storing volume is at a proper level. Therefore
the function is transferred to the step S524 where a judgement is made
about the concentration of carbon dioxide in the gas within the storing
volume 2, and if the carbon dioxide concentration exceeds the reference
value (for example, 3%), then the function is transferred to the step S502
where the motor 35 for the compressor 34 is activated in order to
discharge the carbon dioxide from within the storing volume 2. Then the
function is transferred to the steps S504 to S506 to perform the
operations as described above. If the result of the judgement at the step
S524 indicates that the carbon dioxide concentration with in the storing
volume 2 is below the reference value, it means that the oxygen
concentration is at a proper level and the carbon dioxide level is also
quite low, and therefore the function is returned to the main routine
after turning off the motor 35 and the compressor 34 at the step S526.
Based on this flow chart, if the nitrogen timers N1 and N2 are set, for
example to 3 minutes, the first separating tank 31 and the second
separating tank 32 will carry out the nitrogen concentrating process
alternately for 3 minutes each time. As mentioned above, when one of the
first separating tank 31 and the second separating tank 32 is carrying out
the nitrogen concentrating process, the other one is carrying out the
regenerating process, thereby making it possible to operate the
nitrogen-rich gas supplying device continuously.
FIG. 7 is a flow chart showing the humidity regulating subroutine. As shown
in FIG. 7, a judgement is made at the step S600 as to whether the humidity
within the storing volume 2 is below the first reference value (for
example 70%), and if it is below the first reference value, then the
humidifier 77 is turned on at the step S602 after which the function is
returned to the main routine. If the humidity within the storing volume 2
exceeds the first reference value, then the function is transferred to the
step S604 where a judgement is made as to whether the humidity corresponds
to the second reference value (for example, 100%). If it does, then the
humidifier 77 is turned off at the step S606. If the result of the
judgement at the step S604 indicates that the humidity does not correspond
to the second reference value, then the function is returned to the main
routine. As the result of the operations based on the flow chart of FIG.
7, the humidity within the storing volume 2 is maintained between the
first reference value and the second reference value.
FIG. 8 is a flow chart showing the ethylene regulating subroutine. As shown
in FIG. 8, a judgement is made at the step S700 as to the existence or
absence of ethylene gas. If ethylene is detected, the motor 94 is turned
on at the step S702 to run the motor 94 for a predetermined time. If
ethylene is not detected, the function is transferred to the step S704
where the motor 94 is turned off. As a result of the operations based on
this flow chart, the ethylene within the storing volume 2 can be removed.
Unlike the device described in Japanese Patent Publication No. Sho-60-1200,
the present invention does not provide a combustion type, but a
bottom-installed type fresh food storing device. Therefore, the generation
of CO gas or occurring of a fire is not possible and safety is assured.
In this embodiment of the present invention, if the pressure within the
storing volume 2 does not reach the predetermined value, the storing
volume 2 is sealed off by means of the pressure regulating means 83,
thereby preventing the leaking of the gas from the storing volume 2 to the
outside, and also preventing the intruding of the external air from the
outside through the discharge hole 84 into the storing volume 2.
Meanwhile, if the internal pressure of the storing volume 2 is increased
through the introduction of the nitrogen-rich gas or the external air into
the storing volume 2, the pressure regulating means 83 causes the internal
gas of the storing volume 2 to be discharged through the discharge hole 84
to the outside, thereby preventing the excessive increasing of the
internal pressure of the storing volume 2. Further, in this embodiment,
the nitrogen-rich gas supplying device 30 is activated in response to the
detection signal from the oxygen sensor 75 so that the nitrogen-rich gas
is delivered through the nitrogen-rich gas outlet 60, or the external air
is delivered through the air outlet 66 which is the leading end of the
tube 65. Therefore, the oxygen concentration within the storing volume 2
can be maintained between the first oxygen reference value and the second
oxygen reference value (for exampl together between 1 and 10%), so that
the respiration of the fresh food such as vegetables and the like can be
inhibited, thereby making the device of the present invention suitable for
storing fresh foods in a fresh state and capable of preventing rotting.
Further, in this embodiment of the present invention, the gas within the
storing volume 2 can be circulated by means of the fan 78, and therefore,
a uniform temperature, humidity and gas distribution can be achieved,
thereby contributing to keeping the stored fresh food in a fresh state.
Because the internal gas distribution is uniform, the positions for
installing the thermostat 71, the humidity sensor 72, the ethylene sensor
74, the carbon dioxide sensor 73 and the like can be freely chosen.
Further in this embodiment of the present invention, as mentioned above,
the separating wall 18 having the upper opening 19 and the lower opening
20 is installed within the storing volume 2, the evaporation mechanism 23
of the cooling unit 21 is disposed in the space 22 between the separating
wall 18 and the rear wall 17 of the storing volume 2, and the fan 78 is
installed in the upper opening 19 of the separating wall 18. Therefore,
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