JPH04207121A - Storage device - Google Patents

Abstract

PURPOSE:To prevent quality deterioration of fruits and vegetables by closing a gas feed valve after substitution of gas in a storage house and closing an exhaust valve when pressure in the storage house is returned approximately to atmospheric pressure. CONSTITUTION:Opening and closing of a gas feed valve 8a and an exhaust valve 11 are regulated by a control circuit 7 according to change of a gas concentration ratio in a storage house 2. After replacement of a gas in the storage house is over, the gas feed valve and the exhaust valve are closed. When pressure in the storage house is returned approximately to atmospheric pressure, the exhaust valve is closed and pressure is adjusted so as not to damage fruits and vegetables.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a storage device, and more particularly to a storage device in which a storage chamber is filled with a gas to maintain the freshness of stored items.

2. Description of the Related Art Fresh foods such as vegetables and fruits are generally stored in storage devices to maintain their freshness until they are shipped.

In addition, for long-term storage of these stored items, the inside of the storage room must be kept at a low temperature so that the stored items do not freeze and become inert, the oxygen concentration in the inside atmosphere must be reduced to the minimum necessary, and nitrogen or carbon dioxide must be added. The best method is to control the respiratory action, and this type of research is currently continuing. A storage method that utilizes this phenomenon is called a CA (controlled atmosphere or chondral atmosphere) storage method.

A storage device using this CA storage method has a storage warehouse for storing fruits and vegetables, and an environment that is optimal for storing fruits and vegetables, that is, an atmospheric gas in the warehouse at a predetermined concentration ratio (for example, oxygen (02
) 2 to 3% and carbon dioxide (CO2) 5% gas). In this type of storage device, after fruits and vegetables are initially brought into the storage, the gas supply valve installed in the piping connecting the storage and the gas generation device is opened, and the exhaust valve installed in the exhaust piping of the storage is opened. The valve is opened to supply the optimal gas into the storage, replacing the air in the storage with the optimal gas.

Then, after a predetermined period of time has passed, when the air in the storage is replaced with gas from the gas generator, the gas supply valve and exhaust valve are closed.

In this way, the fruits and vegetables stored in the storage room breathe, so instead of consuming the oxygen gas in the storage room, the fruits and vegetables stored in the storage room breathe.
o2 gas). Therefore, as time passes, the gas concentration ratio in the refrigerator exceeds the lower limit value due to the optimal gas conditions for the fruits and vegetables, and if left as is, the freshness of the fruits and vegetables will deteriorate due to gas disturbance.

Therefore, in the storage device, when the gas concentration ratio in the refrigerator exceeds the upper or lower limit, the gas supply valve and the exhaust valve are opened, and the optimal gas generated by the gas generator is supplied into the refrigerator to replace the gas. and adjust the gas concentration ratio to achieve the optimal gas condition.

Problems to be Solved by the Invention However, in conventional storage devices, when supplying gas into the refrigerator as described above, the gas supply valve and the exhaust valve are simultaneously opened to replace the gas in the refrigerator. Even when gas replacement in the refrigerator was completed, the gas supply valve and exhaust valve were closed at the same time. However, since the gas supplied to the storage via the gas supply valve is pressurized, the entire interior of the storage is pressurized when replacing the gas inside the storage. Therefore, if the gas supply valve and exhaust valve are closed at the same time, the inside of the refrigerator will remain pressurized even after the gas replacement is completed, and fruits and vegetables stored in the refrigerator will be stored in a pressurized atmospheric gas. That will happen. Therefore, conventionally, there has been a problem that if fruits and vegetables are stored under pressure for a long period of time, they may become hard and lose quality.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a storage device that solves the above problems by preventing pressure from remaining inside the storage.

Means for Solving the Problems The present invention provides a storage where stored items are stored, a gas supply source that supplies gas at a predetermined concentration to the storage, and a supply pipe that communicates the storage with the gas supply source. and an exhaust valve provided on a discharge pipe communicating the storage with the outside, and when the gas supply valve and the exhaust valve are opened, the gas in the storage is removed from the gas from the gas supply source. In the storage device, when the gas replacement in the storage is completed and the gas supply valve is closed, the opening of the exhaust valve is extended for a predetermined time so that the pressure in the storage reaches approximately atmospheric pressure. The exhaust valve is further provided with pressure regulating means for closing the exhaust valve when the exhaust valve is closed.

The operation of the working pressure adjusting means makes it possible to maintain the pressure inside the storage at approximately atmospheric pressure, so that the stored items in the storage are not affected by the pressure inside the storage.

Embodiment FIGS. 1 and 3 show a storage device which is an embodiment of the present invention. In each figure, storage device I is roughly referred to as storage 2. Gas separation unit 3. It is composed of a compression unit 4°, a control circuit 7, etc.

In the storage 2, there is a 0□ sensor 5 for detecting the gas concentration ratio in the storage. A Co2 sensor 6 is provided, and one end of a nitrogen supply pipe 8 (hereinafter referred to as N2 pipe) connected to the gas separation unit 3 and a discharge pipe 10 are connected.

The N2 pipe 8 has a gas supply valve 8a made of a solenoid valve,
Each of the exhaust pipes 10 is provided with an exhaust valve 11 made of a solenoid valve. Further, the N2 pipe 8 is connected to a relatively upper position of the storage 2, and the discharge pipe IO is connected to the storage 2 at a relatively upper position.
The connection position is selected at the bottom position. The gas separation unit 3 is a device that is supplied with compressed air from the compression unit 4 and separates and produces nitrogen as a product gas.

The compression unit 4 includes an eraser 15A with an intake filter attached to the intake pipe 14, a compressor 15B, and a dryer 15C.
It will be arranged. Compression unit 4 is compressor 15B
The air sucked from the silencer 15A is compressed by the operation, and the compressed air dehumidified by the dryer 15C is supplied to the gas separation unit 3 via the supply pipe 16.

Next, the configuration of the gas separation unit 3 will be explained. In Figure 1, 21.22 is the 1st. In the second adsorption tank, each adsorption tank 21.22 contains a molecular sieve carphone 21A as an adsorbent that adsorbs oxygen.

22A (shown as satin in FIG. 1) is filled.

Pipes 23 and 24 discharge gas from the adsorption tanks 21 and 22 during desorption, and are connected to a common discharge pipe 25, respectively, and the discharge pipe 25 discharges the adsorbed gas (in this example, adsorbed oxygen). It is supposed to be released into the atmosphere. Adsorption tanks 21 and 2 are located in the middle of the pipes 23 and 24, respectively.
Gas discharge switching valves 26 and 27 are provided, each of which is a solenoid valve that alternately discharges the desorbed gas in each half cycle.

On the other hand, 28.29 is an extraction pipe for taking out nitrogen from the adsorption tank 21.22, and 30 is an extraction pipe connected to each of the pipes 28 and 29. Recirculation extraction switching valves 31 and 32 each consisting of a solenoid valve that opens alternately are provided. Further, the extraction pipe 30 is connected to a nitrogen tank 33 that stores generated nitrogen gas.

In addition, the switching valve 31.32 for taking out the reflux is connected to the adsorption tank 21.2.
When increasing the pressure inside 2, selector valve 34.35 for air supply
The valve is opened substantially at the same time as the valve is opened, and the nitrogen gas in the nitrogen tank 33 is refluxed into the adsorption tank 21.22. In addition, the switching valve 34
．． 35 is arranged between the supply pipe 16 and each adsorption tank 21,22.

36 is a pipe communicating between pipes 28 and 29, 37 is pipe 3
A pressure equalization switching valve consisting of a solenoid valve installed in the middle of 6.
The pressure equalization switching valve 37 is opened for a predetermined short time at the end of a half cycle by the adsorption tanks 21 and 22, and each adsorption tank 21.
Equalize the pressure between the two.

An N2 pipe 8 that supplies nitrogen gas from the nitrogen tank 33 to the storage 2 is connected to the nitrogen tank 33.
As mentioned above, the gas supply valve 8a is disposed in the middle.

The gas separation unit 3 configured as described above repeatedly performs the steps of pressure increase, pressure equalization, and desorption to generate N2 gas.

Note that a detailed explanation of the operation of the gas separation unit 3 will be omitted here.

The gas supply valve 8a and the exhaust valve 11 are connected to the control circuit 7 and are normally closed, and are configured to open in response to a drive signal supplied from the control circuit 7. That is, the control circuit 7 is constituted by a sequence circuit as shown in FIG. 3, and controls the opening and closing of the gas supply valve 8a and the exhaust valve 11 according to changes in the gas concentration ratio in the storage 2.

Since the fruits and vegetables stored in the storage 2 breathe, they generate carbon dioxide (0,) while consuming oxygen (02) in the storage. Therefore, when fruits and vegetables are stored for a long period of time, the gas concentration ratio in the refrigerator increases with time and the CO2 concentration exceeds the allowable range of optimal gas conditions for fruits and vegetables.

The 02 concentration, CO, and concentration in the refrigerator are monitored by the 02 sensor 5 and 02 sensor 6, and the control circuit 7 is controlled by the 02 sensor 5.
．． Co, the gas separation unit 3 by the detection signal of the sensor 6
Controls the supply of N2 gas generated in

Here, the control operation of the control circuit 7 shown in FIG. 2 will be explained. In FIG. 2, 41 represents a solenoid for the gas supply valve 8a, and 42 represents a solenoid for the exhaust valve 11. Also 43,
44 is a relay, and when closed respectively, solenoids 41 and 42
Excite. Reference numeral 45 denotes a delay relay (pressure adjustment means) which keeps the exhaust valve 11 open for a predetermined period of time after the gas supply valve 8a is closed, as will be described later. In addition, delay relay 4
5 remains on for a time t even if the input signal is turned off, and this delay time (1) can be changed to any desired time.

For example, after the stored items such as fruits and vegetables are brought into the storage warehouse 2, the gas inside the warehouse is set to an optimal gas atmosphere (2 to 3% 02, Co
, is adjusted to 5%). Thereafter, when the gas concentration ratio in the refrigerator changes due to the respiration of fruits and vegetables, the control circuit 7 controls the gas supply valve 8a,
Controls the opening and closing of the exhaust valve 11.

Therefore, when the CO2 concentration in the refrigerator exceeds the permissible upper limit of the optimal gas, the switch 46 of the control circuit 7 is closed.

As a result, the relay 43 is energized and the relay 43 is energized.
3, each of the contacts 43a to 43c is closed.

When the contact 43a of the relay 43 is closed, the solenoid 41
is excited, and the gas supply valve 8a is opened.

Therefore, the N2 gas stored in the nitrogen tank 33 of the gas separation unit 3 is transferred to the N2 pipe 8. The gas is supplied into the storage 2 via the gas supply valve 8a. Note that the product gas in the nitrogen tank 33 is N2 gas 99 to 99.9%.

02 is high purity N2 gas with a content of about 1 to 0.1%.

Therefore, as the N2 gas from the nitrogen tank 33 is supplied into the storage 2, the pressure within the storage 2 increases and the CO2 concentration within the storage decreases.

Also, at the same time as the relay 43 is energized, the delay relay 4 is activated.
5 is also energized and contact 45a of delay relay 45 is closed, so relay 44 is also energized. Therefore, contacts 44a and 44b of relay 44 are closed, and solenoid 42 is energized. Therefore, the exhaust valve 11 opens simultaneously with the opening of the gas supply valve 8a. The inside of the refrigerator is pressurized by the supply of N2 gas from the nitrogen tank 33, so when the exhaust valve 11 is opened, the gas inside the refrigerator is exhausted to the outside via the exhaust pipe 11. High CO2 concentration - Gas is exhausted to the outside, and the CO2 concentration inside the refrigerator gradually decreases.

In FIG. 3, the gas supply valve 8a is opened by the operation of the control circuit 7.
3 shows a time chart of signals input to the solenoids 41 and 42 of the exhaust valve 11 and changes in pressure inside the refrigerator.

When the gas in the refrigerator becomes the optimum gas by opening the gas supply valve 7 and the exhaust valve 11, the switch 46 is opened. As a result, the relay 43 is deenergized and the contacts 43a to 43c of the relay 43 are opened.

Therefore, the solenoid 41 is deenergized and the gas supply valve 8a
is closed.

However, the solenoid 42 of the exhaust valve 11 is connected to the delay relay 4.
5, even after the gas supply valve 8a is closed, the relay 44 is kept in an excited state and remains open for a time t. Therefore, the gas remaining in the storage 2 is either pressurized or exhausted to the outside from the exhaust valve 11, and the pressure inside the storage is reduced to approximately atmospheric pressure. The pressure inside the refrigerator changes as shown in the line (2) in FIG. 3, and when the pressure inside the refrigerator reaches approximately atmospheric pressure, the exhaust valve 11 closes.

In this way, the gas concentration ratio in the storage chamber 2 is adjusted so that the gas is optimal, and the pressure is adjusted to approximately atmospheric pressure. Therefore, even if fruits and vegetables stored in the refrigerator are stored for a long period of time, they are prevented from spoiling due to the pressure inside the refrigerator, and deterioration in the quality of the stored products is prevented.

FIG. 4 shows a modification of the present invention. In Fig. 4, discharge pipe 1
0 is provided with a pressure control valve 47 as a pressure regulating means that automatically opens and closes depending on the pressure difference between the upper and downstream sides. This pressure control valve 47 is a pressure detection section 48 or a diaphragm 49.
It is defined into a diaphragm chamber 50 on the upstream side and a diaphragm chamber 51 on the downstream side. The diaphragm 49 is urged in the valve closing direction by the pressing force of the spring 52.

The upstream diaphragm chamber 50 has an upstream discharge pipe 10.
A branch pipe 53 branched further is connected to the diaphragm chamber 51 on the downstream side, and a branch pipe 54 branched from the discharge pipe IO on the downstream side is connected to the diaphragm chamber 51 on the downstream side.

Furthermore, since the tip of the discharge pipe IO is open to the atmosphere,
The diaphragm chamber 51 on the downstream side is at approximately atmospheric pressure.

Further, the pressure inside the storage 2 is introduced into the diaphragm chamber 50 on the upstream side.

Here, as mentioned above, the CO□ concentration in the refrigerator becomes high and the gas supply valve 8a is opened by the control operation of the control circuit 7.
When the pressurized N2 gas in the nitrogen tank 33 is supplied into the refrigerator, the pressure inside the refrigerator increases. Therefore, the pressure control valve 4
High-pressure gas inside the refrigerator is introduced into the diaphragm chamber 50 of the pressure detection section 48 of No. 7. Therefore, the diaphragm 49 moves upward due to the pressure difference between the diaphragm chambers 50 and 51, and the pressure control valve 47 opens. Thereby, the gas in the storage 2 is exhausted to the outside via the exhaust pipe 10.

Then, when the atmospheric gas inside the refrigerator is replaced with the optimal gas,
Gas supply valve 8a is closed. However, since the interior of the refrigerator is pressurized, the pressure control valve 47 remains open to further reduce the pressure inside the refrigerator. When the pressure in the storage chamber 2 is reduced to approximately atmospheric pressure after a predetermined period of time has elapsed, the pressure control valve 47 is automatically closed.

In this manner, by the on-off valve operation of the pressure control valve 47, the storage 2 is controlled to have a gas concentration ratio and pressure suitable for storing fruits and vegetables for a long period of time.

Effects of the Invention As described above, the storage device according to the present invention can adjust the pressure in the storage to approximately atmospheric pressure, so the inside of the storage can be filled with gas suitable for storing stored items such as fruits and vegetables. It is possible to control the concentration ratio and adjust the pressure so that fruits and vegetables are not spoiled.

Therefore, it is possible to prevent quality deterioration of fruits and vegetables, etc.
It has the advantage of being able to store stored items stably for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the storage device according to the present invention, FIG. 2 is a circuit diagram of a control circuit, and FIG. 3 is a diagram showing opening/closing of a gas supply valve and exhaust valve and pressure changes in the chamber. FIG. 4 is a configuration diagram of a modification of the present invention. l... Storage device, 2... Storage, 3... Gas separation unit, 4... Compression unit, 5... 02 sensor, 6... C02 sensor, 7... Control circuit, 8 ...
N2 pipe, 8a... Gas supply valve, lO... Discharge pipe, 11... Exhaust valve, 21.22... Adsorption tank, 33.
...Nitrogen tank, 45...Delay relay, 47...Pressure control valve. Patent applicant Director, Ministry of Agriculture, Forestry and Fisheries Vegetable and Tea Industry Experiment Station
Tokiko Co., Ltd., ζ),

Claims (1)

[Claims] A storage in which stored items are stored, a gas supply source that supplies gas at a predetermined concentration to the storage, a gas supply valve provided in an air supply pipe that communicates the storage with the gas supply source, and the storage and an exhaust valve provided on a discharge pipe communicating with the outside, and in which gas in the storage is replaced with gas from a gas supply source by opening the gas supply valve and the exhaust valve, When the gas replacement is completed and the gas supply valve is closed, the opening of the exhaust valve is extended for a predetermined period of time, and when the pressure in the storage reaches approximately atmospheric pressure, the pressure that causes the exhaust valve to close. A storage device comprising adjustment means.