JPH09287867A - Defrosting control device of refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To defrost an evaporator by heating the evaporator with a discharge gas from a compressor and defrost a zone adjacent to a discharge opening of the evaporator by carrying out an air blowing operation for a given time in a low speed operation mode. SOLUTION: An evaporator 11 is heated by a hot gas discharged from a compressor 6 so that a frost stuck to fins is melted and drips down in a drip pan 16 while a drain water is prevented from being frozen. A usual defrosting control is carried out until a surface temperature Te of the evaporator 11 reaches a given temperature T1 and when the surface temperature Te reaches the temperature T1 , an evaporator fan 18 starts a low speed operation thereof and this low speed operation lasts until the surface temperature Te of the evaporator reaches a temperature T2 . Due to such a construction, an air having a temperature higher than the given temperature T1 is supplied to an area adJacent to a discharge opening of the evaporator 11 so that an abnormal elevation of the inner temperature can be prevented. Particularly, a frost which sticks to a discharge opening 20 of a duct and a grill can be removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrost control device for defrosting an evaporator of a refrigerating device mounted on a refrigerating vehicle or the like, and more particularly to a defrosting device capable of defrosting the vicinity of an outlet of an evaporator. The present invention relates to a defrost control device.

[0002]

2. Description of the Related Art As a conventional refrigerating apparatus, the actual refrigerating machine 57-1
The refrigeration container device disclosed in Japanese Patent No. 21890 has an evaporator body (4) mounted on an inner wall surface facing the opening / closing door (2) of the refrigeration container, and further has an L-shape above the evaporator body (4). The mold is provided with a cool air blowout part (5). This cold air outlet (5)
A first outlet (6) for blowing out cool air substantially parallel to the direction of the opening / closing door (2), and a second outlet (7) for blowing out cool air downward at the lower end of the first outlet (6). And the first
And a switching damper (9) for opening and closing the air outlet (6) and the second air outlet (7) in conjunction with the opening and closing door. Thereby, when the opening / closing door (2) is opened, it is possible to prevent the cool air from being blown out from the opening / closing door (2).

Further, in order to suppress the outflow of cold air and to prevent frost formation on the evaporator due to invasion of outside air, the refrigeration vehicle disclosed in Japanese Utility Model Laid-Open No. 60-183639 discloses a load for loading and unloading luggage. An air curtain device (6) is arranged near the entrance / exit opening (3),
In the refrigerating vehicle disclosed in Japanese Patent No. 0, the air guide duct (D) guides cool air to the vicinity of the opening / closing door (7) and performs the same operation as the air curtain described above.

[0004]

However, in the above-mentioned reference, the invasion of the outside air cannot be completely blocked, and due to the moisture generated from the object to be frozen, the evaporator and the frost near the outlet of the evaporator are frosted. Was attached. Due to the adhesion of the frost, the amount of cold air blown from the evaporator may be limited or may not be blown at all, which causes a problem of impairing the cooling performance.

On the other hand, with respect to frost formation on the evaporator itself, on the other hand, a method of directly discharging high-temperature and high-pressure discharge gas discharged from a compressor to the evaporator to heat the evaporator and defrost the frost attached to the evaporator ( Although hot gas defrosting is known, this method also fails to remove the frost adhering to the vicinity of the evaporator outlet.

Therefore, the present invention is to provide a defrost control device for a refrigerating apparatus that enables defrosting in the vicinity of the outlet of the evaporator.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention is directed to a refrigeration cycle which is constituted by at least an evaporator, a compressor, a condenser and an expansion valve arranged in a freezer for containing a substance to be frozen, and a discharge side of the compressor. In a refrigerating device having a bypass passage communicating with the cooling heat exchanger and an opening / closing means for opening / closing the bypass passage, at least a normal operation mode and this normal operation are provided while air in the refrigerator is blown to the evaporator. And a first defrosting means for supplying the compressor discharge gas directly to the evaporator by opening the bypass passage by the opening / closing means when a defrost request is made. , While the first defrosting means is operating, the blower means is operated at a low speed for a predetermined time. In in that and a second defrost means to operate (claim 1). The predetermined time is preferably 15 seconds to 25 seconds. Further, the normal operation mode is a mode in which the blower as the blower is operated at the rated voltage, and the low speed operation mode is a mode in which the blower is operated at a voltage half the rated voltage. Further, it is desirable that the opening / closing means is a solenoid valve.

Thus, when the defrosting is requested, the bypass passage is opened by the first defrosting means, the compressor discharge gas is supplied to the evaporator to heat the evaporator, and the evaporator is defrosted. Along with the predetermined time of the second defrosting period by the first defrosting means,
Since the blowing means is operated in the low speed operation mode by the defrosting means, the heat of the heated evaporator can be supplied to the vicinity of the outlet of the evaporator to perform defrosting and thawing near the outlet, Can achieve the task.

Further, the present invention is provided with an evaporator temperature detecting means for detecting the surface temperature of the evaporator, and the second defrosting means, when the first defrosting means is in operation,
When the surface temperature of the evaporator detected by the evaporator temperature detecting means becomes equal to or higher than the first predetermined temperature,
The blower is operated in a low speed operation mode, and when the surface temperature of the evaporator reaches a second predetermined temperature which is higher than the first predetermined temperature, the low speed operation mode of the blower means is released. 2). The first predetermined temperature is preferably 4 ° C and the second predetermined temperature is preferably 7 ° C. Further, the evaporator temperature detecting means is preferably a temperature sensor mounted on the fin surface of the evaporator.

Thus, when the surface temperature of the evaporator becomes equal to or higher than the first predetermined temperature, the low speed operation of the blowing means is started, so that the air having a predetermined temperature is supplied near the outlet of the evaporator. Therefore, defrosting can be performed efficiently. Further, when the second predetermined temperature, which is higher than the first predetermined temperature, is reached, the low speed operation mode of the blowing unit is released, so that the temperature rise in the freezer can be suppressed.

Further, according to the present invention, when the surface temperature of the evaporator detected by the evaporator temperature detecting means reaches the second predetermined temperature, the first defrosting means is stopped and the blower means is operated. The first defrosting means is provided with a defrost stopping means for returning to a state before the operation (claim 3).

Thus, when the surface temperature of the evaporator reaches the second predetermined temperature, the defrost control is stopped so that it can be determined that the defrosting of the evaporator and the vicinity of the evaporator outlet has been completed. Since it is possible to suppress the defrost control more than necessary, it is possible to suppress the rise in the internal cold storage temperature.

Further, according to the present invention, a grill is provided at the outlet of the evaporator (claim 4). As a result, it is possible to prevent the fins of the evaporator from being exposed in the freezer, and it is also possible to defrost the frost attached to the grill by the defrost control.
Specifically, it is possible to avoid problems caused by frost on the grill.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

The refrigerating apparatus 1 according to the embodiment of the present invention is
As shown in FIG. 1, for example, an evaporator unit 4 mounted on a refrigeration vehicle 2 arranged inside a refrigeration container 3, and a condenser unit 5 arranged outside the refrigeration container 3.
And a compressor 6 which is arranged in the engine compartment 7 and is connected to a running engine (not shown) via an electromagnetic clutch 8 to rotate.

Further, the structure of the refrigerating apparatus 1 will be described with reference to FIG. 2. The compressor 6 includes a condenser 9 arranged in the condenser unit 5 and an expansion valve 10 (in the evaporator unit 4 in this embodiment). The evaporator 11 and the receiver tank 12 arranged in the evaporator unit 4 are connected in series to form a refrigeration cycle 13.

In the refrigeration cycle 13, the refrigerant compressed by the compressor 6 radiates heat to the air sent by the condenser fan 19 in the condenser 9 and condenses to become a high-pressure low-temperature liquid refrigerant. This liquid refrigerant passes through the expansion valve 10 and undergoes adiabatic expansion to be easily evaporated.
It is sent to the evaporator 11. In this evaporator 11, the heat of the air in the refrigerating container sent by the evaporator fan 18 is absorbed and evaporated, and the receiver tank 12 performs gas-liquid separation to return only a complete gas refrigerant to the compressor 6. is there. As a result, the heat of the air in the freezing container 3 absorbed by the evaporator 11 can be radiated to the air outside the freezing container 3 by the condenser 9, and the temperature in the freezing container 3 can be lowered.

The evaporator unit 4 is shown in FIGS. 3 and 4, for example, and the upper side wall 3a of the refrigeration container 3 is used.
In the case 4a suspended in the
The evaporator fan 18, the expansion valve 10 and the receiver tank 12 are housed. The case 4a has a suction port 22 at one end and a duct 23 at the other end, which is the air outlet 20, and the evaporator fan 18 and the evaporator 11 are arranged in the duct 23. It is what is done. Thus, by operating the evaporator fan 18, the air in the refrigeration container 3 is sucked into the duct 23 and cooled by the evaporator 11, and then the refrigeration container 3 is blown from the outlet 20.
The inside of the freezing container 3 is frozen by being blown out.

Further, a grill 21 is attached to the outlet 20 of the duct 23 located in front of the outlet 11a of the evaporator 11 so as to adjust the outlet direction of the air blown out from the evaporator 11 and at the time of putting in and out the frozen object. Alternatively, the fins of the evaporator 11 are protected from damage due to collision of objects during cleaning.

The refrigeration cycle 13 of the refrigeration system 1
In order to defrost the evaporator 11 and the vicinity of the outlet 11a of the evaporator 11 (for example, the outlet 20 and the grill 21 of the duct 23), the discharge side of the compressor 6 (the compressor 6 and the condenser 9). Bypass passage 14 for connecting the inlet side of the evaporator 11 (between the evaporator 11 and the expansion valve 10)
A solenoid valve 15 is provided on the bypass passage 14 as an opening / closing means for opening / closing the bypass passage 14.

Further, in order to control the refrigerating apparatus 1, at least a central processing unit (CP) (not shown) is used.
U), a read only memory (ROM), a random access memory (RAM), an input / output port (I / O), an output circuit, and a control unit (C / U) 42 are provided. The control unit 40 receives a signal from a temperature sensor 42 that detects the surface temperature Te of the evaporator 11, a temperature sensor 43 that detects the internal temperature Tr of the refrigerating container 3, and an input signal from a switch from the operation panel 41. After being input and processed by a predetermined program, each control device, specifically, the evaporator fan 18, the condenser fan 19, the electromagnetic clutch 8, the drip pan heater device 17, and the electromagnetic valve 15 are controlled as output signals. It is a thing.

The defrost control device according to the present invention in the refrigeration system 1 having the above-mentioned structure blows the air inside the refrigerator to the evaporator and has at least a normal operation mode and a low speed operation mode lower than the normal operation. The blower means, the first defrosting means for supplying the compressor discharge gas directly to the evaporator by opening the bypass passage by the opening / closing means when a defrost request is made, and the first defrosting means A second one in which the blower is operated in a low-speed operation mode for a predetermined time during operation
The defrosting means is provided, and specifically, the defrost control shown in the following flow chart is performed.

Referring to the flow chart shown in FIG. 5, the defrost (DEF) control started from step 100 will be described below. For example, the defrost control switch provided on the operation panel 41 is used for manual defrosting, and for automatic defrosting by a timer. Alternatively, it is started when it is detected that the evaporator 11 or the vicinity of the outlet 11a of the evaporator 11 is frozen. The evaporator 11 or the vicinity of the outlet 11a of the evaporator 11 is frozen when the evaporator 11 is frozen.
It is determined that the surface temperature Te of the evaporator 11 is equal to or lower than the predetermined temperature for a predetermined time, or the surface temperature Te of the evaporator 11 is equal to or lower than the predetermined temperature for the predetermined time, and the internal temperature Tr rises. It is judged by the fact that you started.

When this defrost (DEF) control is started from step 100, the evaporator fan (EVA / FAN) 18 is stopped at step 110, and step 12
At 0, the condenser fan (COND / FAN) 19 is stopped, and at step 130, the solenoid valve 15 is opened to open the bypass passage 14, and the high-temperature and high-pressure discharge gas (hot gas) discharged from the compressor 6 is directly supplied to the evaporator 11. Perform hot gas defrost control. Next, step 14
At 0, the drip pan heater device 17 is energized to defrost the drip pan 16.

As a result, the evaporator 11 is heated by the hot gas supplied to the evaporator 11,
The frost adhering to the fins of the evaporator 11 melts and drips onto the drip pan 16, and since the drip pan 16 is heated, the drowned water is prevented from freezing, and the frost adhering to the evaporator 11 is reliably removed. Is what you can do.

Then, in step 150, the latest evaporator surface temperature Te is read, and in step 160
Then, it is determined whether or not the latest evaporator surface temperature Te is equal to or higher than the first predetermined temperature T ₁ (for example, 4 ° C.). In this determination, when the evaporator surface temperature Te is lower than the first predetermined temperature T ₁ , the process returns to step 150 to read the latest evaporator surface temperature Te,
The hot gas type defrost control is executed until the latest evaporator surface temperature Te becomes equal to or higher than the first predetermined temperature T ₁ .

After that, when the evaporator surface temperature Te rises and becomes equal to or higher than the first predetermined temperature T ₁ , the routine proceeds to step 170, where the latest evaporator surface temperature Te is higher than the first predetermined temperature T _1. Second predetermined temperature T
It is determined whether or not it is ₂ (for example, 7 ° C.) or more. Immediately after the latest evaporator surface temperature Te becomes equal to or higher than the first predetermined temperature T _{1 in} the determination in step 160, the temperature is naturally lower than the second predetermined temperature T ₂ , so the process proceeds to step 180 in the determination in step 170. It will be. Then, in step 180, the low speed operation of the evaporator fan 18 is executed. Specifically, a voltage that is about ½ of the rated voltage is supplied to execute low-speed operation, which allows air having a temperature equal to or higher than the first predetermined temperature to be supplied to the vicinity of the blowout port. Without raising abnormally, near the outlet 11a of the evaporator 11,
In particular, it is possible to remove the frost adhered to the air outlet 20 of the duct 23 and the grill 21. It should be noted that the fact that the first predetermined temperature T ₁ and the second predetermined temperature T ₂ are 4 ° C. and 7 ° C. have been determined by experiments.

Thereafter, when the latest evaporator surface temperature Te read in step 150 becomes equal to or higher than the second predetermined temperature T _{2 in} the determination in step 170, the process proceeds to step 190 and the defrost (DEF) control is performed. Is to be released. Specifically, the evaporator fan 18 is returned to a normal state, and the condenser fan 19
Is operated to close the bypass passage 14 by closing the solenoid valve 15 so that the refrigerant flows through the normal refrigeration cycle 13. Further, the energization of the drib pan heater device 17 is stopped. Thereby, the refrigerator 1
Is to restore the normal operating state.

The above defrost control will be described with reference to the time chart shown in FIG. 6. The defrost control started from t ₁ (COMP ON, EVA / FAN OFF, SOL / V ON, COND
/ FANOFF), the normal defrost control is executed until the evaporator surface temperature Te reaches the first predetermined temperature T ₁ . Then, when the evaporator surface temperature Te reaches the second predetermined temperature T ₁ , the evaporator fan (EVA / FA
N) 18 starts low speed operation, and evaporator surface temperature T
e until the temperature reaches the _second predetermined temperature T ₂ (t ₂ ~
t ₃ ) The low speed operation of the evaporator 18 is continued. Then, when the evaporator surface temperature Te reaches the second predetermined temperature T ₂ , the defrost control is released, and the control of the refrigeration system returns to the state immediately before the defrost control was started.

Further, in the above embodiment, the operating time of the evaporator fan 18 is determined by the evaporator surface temperature Te (from reaching the _first predetermined temperature T ₁ to the second predetermined temperature T ₂₎ . Time to reach t _{2 to} t
₃ ), but the time (t _{1 to} t ₂ ) from when the evaporator surface temperature Te reaches the _first predetermined temperature T ₁ after the defrost control is started, and from the first predetermined temperature T ₁ to the second experimentally determined time t ₂ ~t ₃ to reach a predetermined temperature T ₂ of the one in which may be actuated by a timer. In particular, it has been confirmed by experiments that the optimum time for the low speed operation of the evaporator fan 18 from t _{2 to} t ₃ is 15 to 25 seconds.

[0031]

As described above, according to the present invention, in order to operate the blower at a low speed for a predetermined time during defrost control, the evaporator is defrosted and thawed, and at the same time, near the outlet of the evaporator, especially near the grill. The defrosting and the thawing can be performed, and the reduction of the refrigerating capacity of the refrigerating device can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a state in which a refrigeration system according to an embodiment of the present invention is mounted on a vehicle.

FIG. 2 is an explanatory diagram illustrating an example of the configuration of the refrigerating apparatus according to the embodiment of the present invention.

FIG. 3 is a front view showing an example of an evaporator unit of the refrigeration system.

FIG. 4 is a side view showing an example of an evaporator unit of the refrigeration system.

FIG. 5 is a flowchart showing defrost control by the defrost device of the refrigerating apparatus according to the embodiment of the present invention.

FIG. 6 is a time chart diagram showing defrost control by the defrost device of the refrigerating apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 1 Refrigerating Device 2 Refrigerating Vehicle 3 Refrigerating Container 4 Evaporator Unit 5 Condenser Unit 6 Compressor 7 Engine Room 9 Condenser 10 Expansion Valve 11 Evaporator 11a Evaporator Outlet 13 Refrigeration Cycle 14 Bypass Passage 15 Solenoid Valve 17 Drip Pan Heater 18 Evaporator Fan 19 Condenser Fan 20 Air outlet 21 Grill 23 Duct 40 Control unit 42 Temperature sensor

Claims (4)

[Claims] 1. A refrigeration cycle at least including an evaporator, a compressor, a condenser, and an expansion valve arranged in a freezer containing a substance to be frozen, and a discharge side of the compressor and the cooling heat exchanger are communicated with each other. In a refrigeration system having a bypass passage and an opening / closing means for opening and closing the bypass passage, air is blown into the evaporator, and at least a normal operation mode and a low speed operation mode lower than the normal operation are provided. Means, a first defrosting means for supplying the compressor discharge gas directly to the evaporator by opening the bypass passage by the opening / closing means when a defrosting request is made, and the first defrosting means operates. A second defrosting means for operating the blower means in the low speed operation mode for a predetermined time during A defrost control device for a refrigeration system, which is characterized by 2. An evaporator temperature detecting means for detecting a surface temperature of the evaporator is provided, and the second defrosting means of the evaporator is detected by the evaporator temperature detecting means during operation of the first defrosting means. When the surface temperature becomes equal to or higher than the first predetermined temperature, the blower unit is operated in the low speed operation mode, and the surface temperature of the evaporator reaches the second predetermined temperature higher than the first predetermined temperature. The defrost control device for a refrigerating apparatus according to claim 1, wherein the low speed operation mode of the air blowing means is released in such a case. 3. When the surface temperature of the evaporator detected by the evaporator temperature detecting means reaches the second predetermined temperature, the first defrosting means is stopped and the air blowing means is operated by the first blowing means. 3. The defrost control device for a refrigerating apparatus according to claim 2, further comprising defrost stopping means for returning the defrosting means to the state before the defrosting operation. 4. A grill is provided at the outlet of the evaporator, wherein the grill is provided.
A defrost control device for the refrigeration system described.