JPH07151467A - Cold air dryer - Google Patents

Abstract

PURPOSE:To provide a cold air dryer in which temperature variations are reduced. CONSTITUTION:A cooling device 21 and a reheater 23 are provided within a dryer. High temperature refrigerant discharged from a compressor 6 is condensed by a condenser 8 and are made, after pressure reduction, to flow into the cooling device 21 so as to cool the interior of the dryer. High temperature refrigerant is made to flow into a reheater 23 so as to heat the interior of the dryer. A dryer thermostat 32 is provided for detecting temperature within the dryer. A control circuit 31 controls a motor operated valve 20 so as to adjust the ratio between the flow rates of refrigerant flowing to the reheater 23 and the condenser 21 on the basis of the output of the dryer thermostat 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold air dryer used for drying food or agricultural products.

[0002]

2. Description of the Related Art Conventionally, in this type of cold air dryer, a refrigerant circuit as shown in FIGS. 4 and 5, for example, has been used.
That is, the cold air dryer 100 is composed of a drying cabinet 101 having an interior (not shown) for storing foods to be dried, an indoor unit 140, and a condenser 102, and is provided on the discharge side of a compressor 103 provided on the indoor unit 140 side. Is connected to a three-way valve 104, and one outlet of the three-way valve 104 is connected to a condenser 105 provided in the condenser 102. Reference numeral 106 is a blower for forcedly cooling the condenser 105.

The condenser 105 is connected to a liquid receiver 108 via a check valve 107 provided on the indoor unit 140 side, and the liquid receiver 108 is provided with a cooler provided inside the storage chamber via an expansion valve 109. It is connected to 110. Cooler 110
Is connected to the suction side of the compressor 103 via an accumulator 138 to form an annular refrigeration cycle. The expansion valve 109 detects the temperature on the outlet side of the cooler 110 and adjusts the opening so as to maintain the degree of superheat at a predetermined value.

The other outlet of the three-way valve 104 is connected to a reheater 112 which is provided inside the refrigerator together with the cooler 110 and constitutes a heat exchanger 111.
Is connected to the liquid receiver 108 via a check valve 113. Both the check valve 113 and the check valve 107 have the liquid receiver 108 side in the forward direction. Also, 11
Reference numeral 4 is a blower for forcedly circulating the air that has exchanged heat with the cooler 110 and the reheater 112 in the chamber.

The compressor 10 in front of the three-way valve 104
A defrost circuit 115 is connected to the discharge side of No. 3, and this defrost circuit 115 is connected between the expansion valve 109 and the cooler 110 via the opening / closing valve 116 and the capillary tube 125. The opening / closing valve 116 detects the temperature on the outlet side of the evaporator 110 and opens / closes the defrost circuit 115 (indicated by * 2 in the figure). Further, the three-way valve 104 is controlled by a control circuit 117, and a drying thermostat 118 and a cold storage thermostat 119 for detecting the temperature inside the refrigerator are connected to the control circuit 117 (* 1 in the figure).

The compressor 103 has a cylinder bypass type capacity control circuit 13 which constitutes a capacity control device.
4 attached and connected on-off valves 135, 1 connected in series
A discharge tube and a suction side of the compressor 103 in front of the three-way valve 104 are communicated with each other by a thin tube provided with a check valve 36 and a check valve 137.

Reference numeral 126 is an opening / closing valve, and 120 is a liquid solenoid valve, which is always open. Also 127, 128 and 12
Reference numeral 9 is a dryer, indicator and strainer, respectively, and 130 is an oil control circuit for returning lubricating oil to the compressor 103. From the outlet of the liquid receiver 108, the on-off valve 13
1, a liquid injection circuit 133 for cooling the compressor 103, which is equipped with the thermo-valve 132 and the compressor 108,
It is connected to the.

The operation of the above conventional cold air dryer 100 will be described. The cold air dryer 100 has an inside temperature of, for example, + 15 ° C.
It is used in the range of up to + 30 ° C., and the control circuit 117 is set to the inside temperature of + 15 ° C., for example. Then, the control circuit 117 controls the compressor 10
3 is operated and the flow path of the three-way valve 104 is set to the one outlet direction until the temperature inside the refrigerator decreases to the set temperature.
As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 103 enters the condenser 105 via the three-way valve 104 as shown by the thick line in FIG. 4, radiates heat there and is condensed there, and then receives it via the check valve 107. The liquid enters the liquid container 108, and reaches the expansion valve 109 via the on-off valve 126, the dryer 127, the indicator 128 and the on-off valve 120.

As described above, the expansion valve 109 adjusts the opening based on the temperature on the outlet side of the cooler 110, throttles the condensed and liquefied refrigerant, and supplies it to the cooler 110. The refrigerant flowing into the cooler 110 evaporates, absorbs heat from the surroundings to exert a cooling effect, and is then sucked into the compressor 103 via the accumulator 138.

When the internal temperature drops to the set temperature (+ 15 ° C.) due to such cooling operation, the drying thermostat 1
Control circuit 117 detects the temperature inside the chamber by 18
Switches the flow path of the three-way valve 104 toward the other outlet. As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 103 enters the reheater 112 via the three-way valve 104 as shown by the thick line in FIG. 5, and radiates heat there to exert a heating effect. On the other hand, after the refrigerant is condensed there, the check valve 11
The liquid enters the liquid receiver 108 via 3, and thereafter flows as described above.

Due to such reheat operation, the temperature in the refrigerator is, for example, +
When the temperature rises to 18 ° C. (differential 3 ° C.), the drying thermostat 118 detects an increase in the temperature inside the refrigerator, and the control circuit 117 switches to the cooling operation in FIG. 4 again. Repeat thermal operation. Cooled by cooler 109, reheater 112
Since the air heated by is circulated in the storage by the blower 114, the articles stored in the storage are dried by repeating the cooling / reheating operation.

When the cold storage operation is performed in the cold storage, the three-way valve 104 is forcibly switched to the condenser 105 side, and the cold storage thermostat 119 controls the compressor 103 to keep the cold storage inside the cold storage at a predetermined cold temperature. To maintain.

[0013]

As described above, in the conventional cold air dryer 100, the high-temperature and high-pressure gas refrigerant discharged from the compressor 103 is supplied to the reheater 112 by the three-way valve 104 or is supplied to the condenser 105. Since the flow has been switched, the three-way valve 104 can be switched in a short cycle of 10 to 15 minutes when the differential (difference of opening and closing) of the drying thermostat 118 is set to 3 ° C. as described above, and durability is improved. A problem arises.

Further, since the reheating operation and the cooling operation are switched, even if the differential of the drying thermostat 118 is 3 ° C., the actual fluctuation range of the internal temperature is 10 ° C. or more, and There was also a problem that it became unsuitable for drying.

The present invention has been made to solve the above-mentioned conventional technical problems, and an object of the present invention is to provide a cold air dryer capable of reducing fluctuations in the internal temperature.

[0016]

The cold air dryer of the present invention comprises:
A cooler and a reheater are provided in the refrigerator, the high temperature refrigerant discharged from the compressor is condensed in a condenser, the inside of the refrigerator is cooled by depressurizing and flowing into the cooler, and the high temperature refrigerant is The inside of the refrigerator is made to flow into the reheater to heat the inside of the refrigerator, and the inside temperature detecting means for detecting the inside temperature and the inside of the reheater and the condenser are output based on the output of the inside temperature detecting means. A flow rate adjusting means for adjusting the ratio of the amount of the refrigerant is provided.

Further, in the cold air dryer according to a second aspect of the present invention, in the above, the flow rate adjusting means is constituted by a motor-operated valve provided in a pipe on the inlet side of the reheater or the inlet side of the condenser. .

[0018]

According to the cold air dryer of the present invention, since the flow rate adjusting means for adjusting the ratio of the refrigerant amount flowing into the reheater and the condenser based on the output of the inside temperature detecting means is provided, the inside temperature is reduced. If the temperature decreases, the amount of refrigerant flowing into the reheater is increased by the flow rate adjusting means, and conversely, if the internal temperature rises, the amount of refrigerant flowing into the condenser is increased to flow into the reheater. The amount can be reduced.

Therefore, it is possible to reduce fluctuations in the internal cold storage temperature and to suppress the occurrence of component failure, as compared with the conventional control that involves only switching between reheating and cooling operations.

According to the cold air dryer of the second aspect of the present invention, since the flow rate adjusting valve is constituted by the electric valve provided in the pipe on the inlet side of the reheater or the inlet side of the condenser, It is possible to accurately adjust the ratio of the amount of refrigerant flowing into the heat generator and the condenser.

[0021]

An embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a refrigerant circuit diagram of a cold air dryer 1 of the present invention. That is, the cold air dryer 1 is composed of a drying cabinet 3 having an interior (not shown) for storing articles such as foods to be dried, an indoor unit 2 and a condenser 4, and the discharge of a compressor 6 provided on the indoor unit 2 side. The discharge gas solenoid valve 7 is connected to the side. A pressure control valve 10 is connected by bypass to the inlet side and the outlet side of the discharge gas electromagnetic valve 7, and the outlet side of the discharge gas electromagnetic valve 7 is connected to a condenser 8 provided in the condenser 4. The pressure control valve 10 is for preventing an abnormally high pressure when the discharge gas solenoid valve 7 fails, and 9 is a blower for forcibly cooling the condenser 8.

The compressor 6 is, for example, a scroll compressor as described in detail in the conventional example, and a cylinder bypass type capacity control circuit 11 constituting a capacity control device is attached to the compressor 6. This capacity control circuit 1
1 is an on-off valve 12, 13 and a check valve 1 connected in series
The discharge tube and the suction side of the compressor 6 in front of the discharge gas electromagnetic valve 7 are communicated with each other by the thin tube provided with 4, and the open / close valves 12 and 13 are further communicated with the scroll of the compressor 6. ing. When both the on-off valves 12 and 13 are opened, the refrigerant discharged from the compressor 6 is returned to the suction side and its operating capacity is greatly reduced, the on-off valve 12 is opened, and the on-off valve 13 is opened.
In the state where is closed, the discharged refrigerant is returned to the scroll, and its driving ability is reduced to a small level.

The condenser 8 is connected to a liquid receiver 17 via a check valve 16 provided on the indoor unit 2 side, and the liquid receiver 17 is connected to the liquid receiver 17.
Is connected to a cooler 21 provided in the refrigerator via an expansion valve 19. The cooler 21 is connected to the suction side of the compressor 6 via an accumulator 22 to form an annular refrigeration cycle. The expansion valve 19 detects the temperature on the outlet side of the cooler 21 and adjusts the opening degree to maintain the superheat degree at a predetermined value.

The pipe between the discharge gas solenoid valve 7 and the discharge side of the compressor 6 is branched, and this branched pipe is connected to the reheater 23 provided inside the refrigerator together with the cooler 21. . Further, an electric valve 20 constituting a flow rate adjusting means is provided in the branch pipe on the inlet side of the reheater 23,
The outlet side of the reheater 23 is connected to the liquid receiver 17 via a check valve 24. In both the check valve 24 and the check valve 16, the liquid receiver 17 side is in the forward direction. Further, reference numeral 26 is a blower for forcibly circulating the air that has exchanged heat with the cooler 21 and the reheater 23 in the chamber.

A defrost circuit 27 is connected to the discharge side of the compressor 6, which is in front of the discharge gas electromagnetic valve 7, and this defrost circuit 27 includes an opening / closing valve 28 and a capillary tube 29.
Is connected between the expansion valve 19 and the cooler 21 via. The opening / closing valve 28 detects the temperature on the outlet side of the cooler 21 and opens / closes the defrost circuit 27. Further, a control circuit 31 as a control device constituting the flow rate adjusting means has a drying thermostat 32 as an in-compartment temperature detecting means for detecting the in-compartment temperature, a cold keeping thermostat 33 and a humidistat for detecting in-compartment humidity. 34 is connected.

The electrically operated valve 20 drives an actuator that closes the valve seat by, for example, a pulse motor, and the opening thereof can be changed substantially continuously within the range of fully closed to 100% open (fully open). The opening degree of the electrically operated valve 20 is controlled by the control circuit 31 (indicated by * 1 in the figure). That is, the control circuit 31 changes the valve opening degree of the motor-operated valve 20 substantially continuously based on the temperature inside the refrigerator detected by the drying thermostat 32, for example, between fully closed and 50% open to 100% open.

From the outlet of the liquid receiver 17, the on-off valve 30,
A liquid injection circuit 38 including a liquid solenoid valve 36 and a thermo valve 37 is connected to the compressor 6. Further, 39 is an opening / closing valve and 41 is a liquid solenoid valve which is always open. Further, 42, 43 and 44 are dryers,
An indicator and a strainer, and 46 is an oil control circuit for returning lubricating oil to the compressor 6.

Next, the operation of the cold air dryer 1 of the present invention having the above construction will be described. The temperature inside the cold air dryer 1 is, for example, +1
It is used in the range of 5 ° C. to + 30 ° C., and it is assumed that the control circuit 31 is set to the inside temperature of + 15 ° C., for example. Also, during the drying operation, the discharge gas electromagnetic valve 7 is open. Then, assuming that the motor-operated valve 20 is now opened at a certain opening degree, when the control circuit 31 operates the compressor 6, the high-temperature and high-pressure gas refrigerant discharged from the compressor 6 requires the trouble of the discharge gas solenoid valve 7. In the reheater 23
And the condenser 8 direction.

The high-temperature and high-pressure gas refrigerant that has flowed into the condenser 8 through the discharge gas electromagnetic valve 7 radiates heat there and is condensed,
The liquid enters the liquid receiver 17 via the check valve 16 and reaches the expansion valve 19 via the liquid solenoid valve 41. The expansion valve 19 is the cooler 2 as described above.
The opening degree is adjusted based on the temperature of the outlet side of 1, and the condensed and liquefied refrigerant is squeezed and supplied to the cooler 21. The refrigerant that has flowed into the cooler 21 evaporates, absorbs heat from the surroundings, exerts a cooling effect, and is then sucked into the compressor 6 via the accumulator 22.

On the other hand, the high-temperature and high-pressure gas refrigerant flowing into the reheater 23 through the motor-operated valve 20 radiates heat there and exerts a heating action. On the other hand, after the refrigerant is condensed there, the check valve 2
After passing through 4, the liquid enters the liquid receiver 17, merges with the refrigerant from the condenser 8, and thereafter flows as described above. The inside of the refrigerator is dried by the heating action of the reheater 23 and the cooling action of the cooler 21.

Here, when all the high-temperature high-pressure gas refrigerant discharged from the compressor 6 flows toward the reheater 23, the reheater 2
As shown in the Mollier diagram of FIG. 2, the heating heat quantity of No. 3 and the cooling heat quantity of the cooler 21 are about 1.2 times the cooling heat quantity. That is, in the conventional cold air dryer, the temperature inside the chamber was increased due to the difference in the amount of heat during the reheat operation.

Therefore, by adjusting the opening degree of the motor-operated valve 20, about 80% of the discharged gas refrigerant amount from the compressor 6 is supplied to the reheater 23 side and the remaining 20% is supplied to the condenser 8 side. For example, the heating heat quantity and the cooling heat quantity are in equilibrium,
If the disturbance and the change of load are not taken into consideration, the temperature inside the refrigerator theoretically does not change.

Therefore, based on the output of the drying thermostat 32, the control circuit 31 causes the opening degree (%) of the motor-operated valve 20 to be inversely proportional to the temperature rise when the internal temperature becomes higher than the preset temperature (+ 15 ° C.). Reduce the reheater 2
The amount of refrigerant flowing into the condenser 3 is decreased, and the amount of refrigerant flowing into the condenser 8 is increased. Then, when the internal temperature becomes lower than the set temperature (+ 15 ° C.), the opening degree (%) of the motor-operated valve 20 is increased in inverse proportion to this temperature decrease, and the amount of refrigerant flowing into the reheater 23 is increased. At the same time, the amount of refrigerant flowing into the condenser 8 is reduced.

That is, the control circuit 31 finely or continuously adjusts the ratio of the amounts of the high-temperature high-pressure gas refrigerant flowing into the reheater 23 and the condenser 8 on the basis of the internal temperature, so that the internal temperature changes. The width becomes extremely small, and it becomes possible to control the temperature substantially constant around the set temperature (+ 15 ° C.) with high precision. Further, since the three-way valve is not used as in the conventional case, the occurrence of failure of the three-way valve due to frequent switching of reheat / cooling operation can be eliminated.

When the cold storage operation is performed in the refrigerator, the control circuit 31 fully closes the electric valve 20. Further, in the embodiment, the motor-operated valve 20 is provided in the branch pipe on the reheater 23 side, but as shown in FIG. 3, the motor-operated valve 20 is provided in the pipe between the compressor 6 and the condenser 8 to reheat the reheater. The discharge gas solenoid valve 7 may be provided in the branch pipe on the container 23 side. However, in this case, it goes without saying that the opening degree adjustment of the motor-operated valve 20 is the reverse of the above-mentioned operation and the motor-operated valve 20 is fully opened and the discharge gas solenoid valve 7 is fully closed when the cold insulation operation is performed.

[0036]

As described above in detail, according to the present invention, the flow rate adjusting means for adjusting the ratio of the refrigerant amount flowing into the reheater and the condenser based on the output of the internal temperature detecting means is provided.
When the temperature inside the refrigerator has decreased, the amount of refrigerant flowing into the reheater is increased by the flow rate adjusting means, and conversely, when the temperature inside the refrigerator has increased, the amount of refrigerant flowing into the condenser is increased to the reheater. The amount of refrigerant flowing in can be reduced.

Therefore, it is possible to reduce fluctuations in the internal cold storage temperature and to suppress the occurrence of component failures, as compared with the conventional control that involves only switching between reheating and cooling operations.

Further, according to the second aspect of the invention, since the flow rate adjusting valve is constituted by the electric valve provided on the inlet side of the reheater or the pipe on the inlet side of the condenser, the reheater and the condenser are connected. It is possible to accurately adjust the ratio of the amount of refrigerant flowing into the container.

[0039]

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a cold air dryer of the present invention.

FIG. 2 is a diagram showing the relationship between the heating heat amount in the reheater and the cooling heat amount in the cooler of the cold air dryer of the present invention.

FIG. 3 is a refrigerant circuit diagram showing another embodiment of the cold air dryer of the present invention.

FIG. 4 is a refrigerant circuit diagram showing a refrigerant flow during a cooling operation of a conventional cold air dryer.

FIG. 5 is a refrigerant circuit diagram showing a refrigerant flow during a reheat operation of a conventional cold air dryer.

[Explanation of symbols]

 1 Cold Air Dryer 6 Compressor 8 Condenser 19 Expansion Valve 20 Motorized Valve 21 Cooler 23 Reheater 31 Control Circuit 32 Drying Thermostat

Claims (2)

[Claims] 1. A cooler and a reheater are provided in the refrigerator, the high temperature refrigerant discharged from the compressor is condensed by a condenser, the pressure is reduced, and the refrigerant is allowed to flow into the condenser to cool the refrigerator. Along with, in the cold air dryer that heats the inside of the refrigerator by flowing the high-temperature refrigerant into the reheater, the inside temperature detecting means for detecting the inside temperature, and the output based on the output of the inside temperature detecting means. A cool air dryer, comprising: a reheater and a flow rate adjusting means for adjusting the ratio of the amount of refrigerant flowing into the condenser. 2. The cool air dryer according to claim 1, wherein the flow rate adjusting means is constituted by an electrically operated valve provided in a pipe on the inlet side of the reheater or the inlet side of the condenser.