JP2643671B2 - Operation control device for refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control apparatus for a refrigerating apparatus, and more particularly to an improvement in an apparatus for controlling the temperature of a space to be controlled using the temperature of air blown from an evaporator as an index.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 59-1977
As disclosed in Japanese Patent No. 64, in a container refrigeration apparatus provided with a refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected, an outlet temperature sensor for detecting the temperature of the outlet air is provided by an evaporator. It is arranged at a predetermined position on the blowout side corresponding to the end of the flow divider side, and controls the capacity of the evaporator based on the detection value of this blowout temperature sensor, for example, the opening degree of the expansion valve, the capacity of the compressor, the By controlling the air volume, etc.
It is a known technique to maintain the temperature in the refrigerator at an appropriate temperature.

[0003]

In the case where the capacity of the evaporator of the refrigerating apparatus is controlled based on the temperature of the blown air as in the above-described conventional apparatus, the temperature sensor is usually attached to a portion corresponding to the flow divider of the evaporator. The reason for this is that the flow divider side is a connection position with the liquid pipe, and particularly in a state where the amount of circulating refrigerant is small, it corresponds to a portion where the temperature is usually the lowest.

[0004] However, when the amount of circulating refrigerant increases, the blow-out temperature of another part of the evaporator may be lower than that of the part on the side of the flow divider. At that time, like the above conventional one,
If the capacity of the evaporator is controlled in accordance with the detection value of the temperature sensor installed on the side of the flow divider, the temperature is controlled using a temperature higher than the actual internal temperature as an index.
In spite of the fact that the temperature must be controlled at a temperature of at least 0 ° C., the temperature in the refrigerator has dropped to 0 ° C. or less, and there has been a fear that fruits and the like, which are cargoes in the refrigerator, freeze and deteriorate the quality.

[0005]

In order to achieve the above object, the means of the first aspect of the present invention comprises a compressor (1), a condenser (2), and an expansion valve (3) as shown in FIG. ) And a refrigeration system including a refrigerant circuit (6) in which an evaporator (4) provided with an evaporator fan (4a) is sequentially connected.

[0006] As an operation control device of the refrigeration system,
The header (1) from the side of the flow divider (12) of the evaporator (4).
A plurality of temperature sensors (Th1), (T1) and (T1) which are separately arranged at the outlet side corresponding to the plurality of portions up to the side 3) and individually detect the temperature of the air blown out from each portion of the evaporator (4).
h2),... and the detected values of the temperature sensors (Th1), (Th2),. When the temperature is equal to or lower than a predetermined temperature near the temperature, a sensor selecting means (21) for selecting a temperature sensor having the lowest detected temperature value among the temperature sensors (Th1), (Th5),. A capacity control means (2) for controlling the capacity of the evaporator (4) based on the blown air temperature detected by the control sensor selected by (21).
0).

[0007] The means adopted in the second aspect of the present invention is that the sensor selecting means (21) in the first aspect of the present invention is arranged such that, immediately after the start of operation, the blower side corresponding to the portion closest to the flow divider (12). The temperature sensor (Th1) arranged at a predetermined position is selected as a control sensor.

[0008]

With the above arrangement, according to the first aspect of the present invention, during operation of the refrigeration system, the plurality of temperature sensors (T) installed on the outlet side of the evaporator (4) by the sensor selection means (21).
h1), (Th2),..., the temperature sensor that detects the lowest temperature is selected as the control sensor, and the evaporator (20) is operated by the capacity control means (20) so that the detection value of the control sensor converges to the set temperature. 4) The ability is adjusted.

In this case, when the refrigerant circulation amount is small, that is, when the degree of superheat is large, the flow divider (1) of the evaporator (4) is not used.
2) When the temperature in the vicinity is the lowest, but when the refrigerant circulation amount is large and wet, the temperature distribution in the evaporator (4) changes, and the outlet air temperature in the vicinity of the flow divider (12) is not always the lowest temperature. . Therefore, if the control is always performed based on the detected value of the temperature sensor installed near the flow divider (12), even if the apparent blown air temperature is maintained near the set value, the apparent air temperature from other parts may be reduced. The temperature of the blown air may be lower than that, which may cause overcooling of the control target space. However, the temperature sensors (Th1), (Th2),... The capacity of the evaporator (4) is adjusted based on the detection value of the temperature sensor having the lowest detection value among the above, so that the difference between the actual blown air temperature and the control temperature is eliminated, and overcooling of the control target space is prevented. Will be done.

According to a second aspect of the present invention, in the first aspect of the present invention, the shunt (1) is provided by the sensor selecting means (21).
The temperature sensor (Th1) closest to 2) is selected as the control sensor. That is, since the amount of circulating refrigerant is small at the start of operation and the air is likely to be overheated, the temperature of air blown out from the vicinity of the flow divider (12) is often the lowest. Therefore, control is simplified by selecting such a control sensor. , And an effect of preventing supercooling is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a refrigerant piping system of a container refrigeration apparatus according to the present invention, wherein (1) shows a compressor,
(2) is a condenser, (3) is an electric expansion valve, (4) is installed in a refrigerator, and four evaporator fans (4a), (4a), ...
Wherein each of the above devices (1) to (4)
Are sequentially connected by a refrigerant pipe (5) to form a closed circuit refrigerant circuit (6) through which the refrigerant circulates. That is,
In the refrigerant circuit (6), the refrigerant discharged from the compressor (1) is condensed and liquefied in the condenser (2), expanded in the electric expansion valve (3), evaporated in the evaporator (4), and then compressed. By circulating back to the machine (1), cold heat obtained by heat exchange with the outside air (or cooling water) in the condenser (2) is given to the inside air in the evaporator (4). ing.

A hot gas bypass passage (10) for bypassing hot gas is provided from a discharge pipe of the compressor (1) to an inlet liquid pipe of the evaporator (4), and the hot gas bypass passage (10) is provided. Is provided with a drain pan heater (11) for heating the evaporator (4). Further, a three-way valve (9) having a flow control function is provided at a branch portion between the discharge pipe and the hot gas bypass passage (10), and when the evaporator (4) is frosted, a three-way valve is provided. The frost formation is melted by opening the valve (9) to bypass the discharged refrigerant toward the hot gas bypass passage (10) and heating the evaporator (4).

[0013] Here, in the drain pan (8) on the blow-out side below the evaporator (4), the flow divider (1) of the evaporator (4) is used.
A plurality of parts corresponding to each part from 2) to the header (13) are provided with five first to fifth temperature sensors (Th) for individually detecting blown air passing through each part of the evaporator (4).
1) to (Th5) are arranged, and outputs of the respective temperature sensors (Th1) to (Th5) are connected to a controller (20) that controls the operation of the container refrigeration apparatus so as to be inputtable.

FIG. 2 shows the contents of the selection control of the control sensor by the controller (20). After starting, in step ST1, the control sensor (Thc) for controlling the capacity of the evaporator (4) is used. , Each of the above temperature sensors (Th
1) to (Th5), the first temperature sensor (Th1) arranged at the position closest to the flow divider (12) is selected, and in step ST2, any one of the temperature sensors (Th1) to (Th5) is selected. Of the temperature sensor Trn (n = 1 to
It is determined whether or not 5) is equal to or less than a predetermined value 0.5 (° C.) near the freezing start temperature, and if not Trn ≦ 0.5 (° C.), it is determined that any temperature sensor may be used as the control sensor. , First
The temperature sensor (Th1) is used as a control sensor. On the other hand, when Trn ≦ 0.5 (° C.) in the determination in step ST2, it is determined that there is a possibility of freezing, and the process proceeds to step ST3.
To perform the control for selecting the temperature sensor indicating the lowest temperature. That is, in step ST3, the temperature sensor showing the lowest detected value among the other temperature sensors (Th2 at the start-up) except for the currently selected temperature sensor (Th1 at the start-up) is compared with the sensor for comparison (Thm). And in step ST4, the comparison temperature sensor (Thm)
Is lower than the detection value Trc of the control sensor (Thc) by 0.5 (° C.) or more, that is, Tr
c> Trm + 0.5 (° C.) to determine whether Trc> T
If it is not rm + 0.5 (° C.), the control sensor (Th
Returning to step ST3 without changing c),
The control of steps ST3 and ST4 is repeated.

On the other hand, in the determination of step ST4, Trc> T
rm + 0.5 (° C.), and if the state continues for 10 minutes or more as determined in step ST5, step ST6
To switch the comparison sensor (Thm) to the control sensor (Thc), and further to step ST7.
It is determined again whether Trn ≦ 0.5 (° C.) and Tr
If n ≦ 0.5 (° C.), the temperature sensor switched under the control of step ST6 is used as it is for the control sensor (Thc).
If Trn ≦ 0.5 (° C.), step ST3
Then, the selection and switching control of the control sensor (Thc) are executed. Although omitted in the above flow, immediately after the end of the defrost operation, the temperature sensor that was the control sensor before the start of the defrost operation is directly selected as the control sensor.

Then, the controller (20) compares the detection value Trc of the control sensor (Thc) selected by the above control with the set temperature Ts to determine the opening of the electric expansion valve (3) and the evaporator fan. (4a), (4a),... Are controlled, and the controller (20) functions as capacity control means according to the first and second aspects of the present invention.

Each step S shown in the above flow chart
By the control of T1 to ST5, the sensor selecting means (21) according to the first and second aspects of the present invention is configured.

Therefore, in the above embodiment, during operation of the refrigeration system, the plurality of temperature sensors (Th) installed on the outlet side of the evaporator (4) by the sensor selecting means (21).
The temperature sensor that detects the lowest temperature among 1) to (Th5) is selected as the control sensor (Thc), and the detection value Trc of the control sensor (Thc) is set by the controller (capacity control means) (20). As compared with the temperature Ts,
The capacity of the evaporator (4) by hot gas bypass or the like is adjusted.

Here, as generally performed, when the performance of the evaporator (4) is controlled based on the blown air temperature detected by a temperature sensor attached to a portion corresponding to the flow divider (12), When the refrigerant circulation amount is small, that is, when the degree of superheat is large, the flow divider (1) of the evaporator (4) is
2) Since the temperature in the vicinity is the lowest, there is no problem. However, when the refrigerant circulation amount is large and wet, the temperature distribution in the evaporator (4) changes, and the temperature of the blown air near the flow divider (12) is not necessarily the lowest temperature. Not necessarily. Therefore, even if the apparent blowing air temperature is maintained near the set value, the blowing air temperature from other parts may be lower than the freezing start temperature, in which case the quality of the fruit or the like is impaired by freezing. Will be.

However, in the above-described embodiment, the sensor with the lowest detection value among the temperature sensors (Th1) to (Th5) installed at a plurality of locations is used as the control sensor (Thc), and the control sensor (Thc) Since the capacity of the evaporator (4) is adjusted based on the detected value, the temperature of the blown air does not drop below the freezing temperature, and the quality of the cargo is well maintained.

In the above embodiment, the first temperature sensor (Th1) disposed closest to the flow divider (12) is used as a control sensor immediately after the start of operation. However, the present invention is not limited to this embodiment. The average value of the detected values of the temperature sensors (Th1) to (Th5) is used at the start of operation or when the detected value of any temperature sensor is not 0.5 (° C.) or less. You may. However, at the start of the operation, since the amount of circulating refrigerant is small and the air is likely to be overheated, the temperature of the air blown out from the vicinity of the flow divider (12) is often the lowest, so that the first temperature sensor (Th
By using 1) as the control sensor (Thc), not only the control can be simplified, but also the effect of preventing freezing can be effectively exerted.

Further, as in the above embodiment, the temperature is lower than the current control sensor (Thc) by a constant temperature (0.5 ° C. in the above embodiment) continuously for a predetermined time (10 minutes in the above embodiment). When there is another temperature sensor (the comparison sensor (Thm) in the above embodiment) to be detected, the other temperature sensor (Thm) is switched to the control sensor (Thc) so that appropriate stability can be obtained. The selection and switching of the control sensor (Thc) can be performed while holding.

In the above embodiment, five (Th1) to (Th5) are provided as a plurality of temperature sensors. However, the present invention is not limited to such an embodiment.
Needless to say, the number may be one or six or more.

[0024]

As described above, according to the first aspect of the present invention, an operation control device for a refrigerating apparatus having a refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected is provided. A plurality of temperature sensors are installed at a position corresponding to the header from the flow divider of the evaporator, and the temperature sensor having the lowest detected temperature value among the temperature sensors is used as a control sensor, and the temperature of the blown air detected by the control sensor is determined. Based on the control of the evaporator, even if the lowest temperature position of the evaporator changes according to the progress of the operation, the control caused by the difference between the actual blowout temperature and the detection value of the temperature sensor Undercooling of the target space can be effectively prevented.

According to the second aspect of the present invention, in the first aspect of the present invention, immediately after the start of the operation, the temperature sensor arranged closest to the shunt is selected as the control sensor. The temperature of the blown-out air can be controlled by the temperature sensor disposed at the lowest temperature position immediately after the start of the operation with a small amount of the circulating refrigerant, so that a significant effect can be exerted.

[Brief description of the drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration apparatus according to an embodiment.

FIG. 2 is a flowchart showing control contents of a controller according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Electric expansion valve 4 Evaporator 4a Evaporator fan 6 Refrigerant circuit 12 Divider 13 Header 20 Controller (capacity control means) 21 Sensor selection means Th1-Th5 Temperature sensors

Claims (2)

(57) [Claims] 1. A refrigerant circuit (6) comprising a compressor (1), a condenser (2), an expansion valve (3) and an evaporator (4) provided with an evaporator fan (4a) connected in order. In the refrigerating device, the header (1) is placed from the side of the flow divider (12) of the evaporator (4).
A plurality of temperature sensors (Th1), (T1) and (T1) which are separately arranged at the outlet side corresponding to the plurality of portions up to the side 3) and individually detect the temperature of the air blown out from each portion of the evaporator (4).
h2),... and the detected values of the temperature sensors (Th1), (Th2),. When the temperature is equal to or lower than a predetermined temperature around the temperature, a sensor selecting means (21) for selecting a temperature sensor having the lowest detected temperature value among the temperature sensors (Th1), (Th2),. A capacity control means (2) for controlling the capacity of the evaporator (4) based on the blown air temperature detected by the control sensor selected by (21).
0) An operation control device for a refrigeration system, comprising: 2. The operation control device for a refrigeration system according to claim 1, wherein the sensor selection means (21) is located at a predetermined position on the blow-off side corresponding to a portion closest to the flow divider (12) immediately after the operation is started. An operation control device for a refrigeration system, wherein the disposed temperature sensor (Th1) is selected as a control sensor.