JPH0510969U - Refrigerator control unit for refrigerated vehicles - Google Patents

Abstract

(57) [Summary] [Purpose] To enable efficient cooldown in the "control unit for refrigerators for cold storage vehicles". [Configuration] The CPU 20 calculates a temperature deviation based on the set temperature of the temperature setter 15 and the internal temperature detected by the suction temperature sensor 3. Further, the CPU 20 retrieves desired air volume data from the storage unit 21 based on this temperature deviation and the outside air temperature detected by the outside air sensor 16,
The air flow rate control unit 23 applies a desired voltage to the evaporator fan based on this. [Effect] The cool down can be efficiently performed, and the power consumption of the evaporator fan can be reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a control device for a refrigerator for a refrigerating vehicle capable of improving the cooldown performance in the refrigerating compartment of the refrigerating vehicle.

[0002]

[Prior Art]

 Generally, it is necessary to keep fresh foods at the optimum temperature for their transportation according to their type, so cold trucks are used for transportation. An example of this cold storage vehicle is disclosed in Japanese Patent Laid-Open No. 62-210373, and a general configuration of a general cold storage vehicle is as shown in FIG. A cooling unit 2 which constitutes a part of a refrigerator is provided in a luggage compartment 1 in which a cold-insulated product is mounted. In the cooling unit 2, an evaporator that cools the air in the luggage compartment 1 and a blower that circulates the air in the luggage compartment 1 through the evaporator as shown in the figure are built in. The cooling unit 2 also has a built-in suction temperature sensor 3 that detects the temperature of the air immediately before it is sent to the evaporator. The temperature detected by this sensor 3 is set in the cab 4 as the inside temperature. It is input to the control device 5 that is being operated. The control device 5 controls the operation of the compressor 6 which supplies the refrigerant to the evaporator based on the internal temperature. The heat absorbed through the evaporator is radiated by the condenser 7 provided outside the vehicle. It should be noted that loading and unloading of luggage in the luggage compartment 1 is performed through the door 8.

FIG. 5 is a schematic configuration diagram of a cooling system of a refrigerator and its control system. The evaporator 12 and the condenser 7 are connected to each other via a flow control element 9 such as a compressor 6 and a liquid tank. The air cooled by the evaporator 12 is blown into the luggage compartment 1 by an evaporator fan 10 rotating at a constant rotation speed. The heat radiation from the condenser 7 is forcibly performed by the condenser fan 11. On / off of the compressor 6 and operation control of the evaporator fan 10 and the condenser fan 11 are performed by the control device 5, and the control is performed by various sensors 13 such as the suction temperature sensor 3 arranged in the refrigerating vehicle. It is performed based on a detection signal or the like.

[0004]

[Problems to be solved by the device]

 However, in the conventional refrigerator control device as described above, the number of revolutions of the evaporator fan 10 is always constant regardless of the temperature in the luggage compartment 1 or the outside air temperature. Experiments conducted by the inventors revealed that a defect occurred. Specifically, conventionally, when the cooldown of the luggage compartment 1 is performed, the compressor 6 is operated at the maximum capacity and the evaporator fan 10 is also operated with the maximum air volume so that the temperature inside the luggage compartment 1 is reduced. The control was such that the compressor 6 was operated intermittently while keeping the evaporator fan 10 at the maximum air volume. Such controls have been made on the assumption that they will be efficient. Especially, during cool down, the compressor 6 and the evaporator fan 10 were in the state of maximum performance, so the cool down should have been performed in the shortest time. However, experiments conducted by the inventors revealed that the conventional control was not always efficient.

Generally, the heat load QL of a refrigerated vehicle is expressed by the following equation. QL = KF (ta-tr) * 1.2 + (0.54 * VB + 3.22) * (ta-tr) * C In the above equation, K is the heat flow coefficient of the container and F is the heat transfer area of the container. Where VB is the internal volume of the container, ta is the outside air temperature, tr is the set temperature in the refrigerator, and C is a coefficient associated with the number of times the door is opened and closed. The values 1.2, 0.54 and 3.22 are constant values obtained by experiments. Here, the K value is usually determined only by the type and thickness of the heat insulating material and is considered to be irrelevant to other factors. However, according to experiments, it was found that this K value changes as shown in the graph in Fig. 6 depending on the air volume in the refrigerator. This figure shows the correlation between the K value of the luggage compartment 1, that is, the proportional constant value and K value of the amount of heat flowing out of the luggage compartment 1, and the air volume blown by the evaporator fan 10, that is, the air flow rate. is there. Although this figure is obtained by an experiment, the K value increases according to the amount of air blown by the evaporator fan 10, as is clear from this experiment. That is, since a large K value indicates a large heat load, it can be understood that the amount of heat flowing out from the luggage compartment 1 increases as the amount of air blown increases. From this, it can be said that, in order to improve the cool down performance, even if the air flow rate is simply set to the maximum, the cool down is not always performed efficiently. It can be said that the reason for such experimental results is due to the structure of the luggage compartment 1 of the cold storage vehicle. In other words, the outer wall portion of the luggage compartment 1 is filled with a heat insulating material, but in order to maintain the strength of the outer wall itself, a reinforcing member is attached to the outer wall portion in place of the heat insulating material. It is considered that the amount of heat entering from this part may increase as the amount of circulating air in the luggage compartment 1 increases.

Further, experimental results supporting this will be described with reference to FIGS. 7 to 9. The experimental results shown in Fig. 7 show the relationship between the cooling capacity of the refrigerator and the amount of heat flowing out from the luggage compartment 1 when the outside air temperature is 35 ° C and the temperature inside the luggage compartment 1 is 10 ° C, in relation to the air flow rate by the evaporator fan 10. It is a thing. Under such a condition, the refrigerating capacity of the refrigerator is sufficiently larger than the amount of heat outflowing from the luggage compartment 1, so that the effect of the air volume is not significantly affected. However, if the difference between the refrigeration capacity and the outflowing heat quantity, that is, the air volume that maximizes the surplus capacity, the cooldown will be performed efficiently. The cooling capacity of the refrigerator has the characteristic that it increases as the amount of air passing through the evaporator increases, and the rate of increase increases as the temperature inside the refrigerator increases. The experimental results shown in FIG. 8 are obtained when the temperature inside the luggage compartment 1 is 0 ° C. and the other temperature conditions are the same as those in FIG. 7. When the temperature in the luggage compartment 1 decreases to 0 ° C. in this way, the cooling capacity of the refrigerator decreases as shown in FIG. 7, while the outflowing heat increases. The outflowing heat quantity tends to be greatly affected by the air volume, and the surplus capacity tends to decrease as the air volume increases. Further, the experimental results shown in FIG. 9 are obtained when the temperature inside the luggage compartment 1 is −18 ° C. and the other temperature conditions are the same as those in FIG. 7. When the temperature inside the luggage compartment 1 is lowered to -18 ° C, the cooling capacity is significantly reduced as shown in the figure, but the outflowing heat amount is increased. In addition, this outflowing heat quantity greatly increases with the increase of the air volume. What can be said from the above experimental results is that as the temperature inside the luggage compartment 1 decreases, the refrigerating capacity decreases, and conversely the outflowing heat amount increases, and the temperature inside the luggage compartment 1 increases. This means that the surplus capacity required for freezing tends to decrease as the air volume increases as the temperature decreases. The conclusions obtained from these experimental results are that if the air volume is appropriately reduced according to the temperature decrease in the luggage compartment 1, a cool down using a region with a large surplus capacity is realized and the time required for cool down That is, it can be shortened considerably. It is an object of the present invention to provide a control device for a refrigerator for a refrigerating vehicle capable of performing efficient cooldown based on the above experimental results.

[0007]

[Means for Solving the Problems]

 The present invention for achieving the above object includes an evaporator that cools air in a refrigerating compartment, a blower that circulates air in the refrigerating compartment through the evaporator, and a cooling capacity of the evaporator that determines the amount of air blown from the blower. With the cooling capacity calculation means, the outflow heat quantity calculation means for calculating the outflow heat quantity from the refrigerating chamber in relation to the air flow rate, the cooling capacity calculation means and the outflow heat quantity calculation means, respectively. An air flow rate calculating means for calculating an air flow rate that maximizes the cooling surplus capacity of the evaporator based on the determined cooling capacity and the outflowing heat amount.

[0008]

[Action]

 The present invention configured as described above operates as follows. The cooling capacity calculation means calculates the cooling capacity of the evaporator in relation to the amount of air blown from the blower. For example, when the air volume is A, the cooling capacity is a, and when the air volume is B, the cooling capacity is b. Further, the outflow heat amount calculating means calculates the outflow heat amount from the refrigerating chamber in relation to the air flow amount in the blower. For example, when the air volume is A, the outflow heat quantity is α, and when the air volume is B, the outflow heat quantity is β. The air flow rate calculation means determines the air flow rate that maximizes the cooling surplus capacity of the evaporator, based on the cooling capacity and the outflow heat quantity calculated by the cooling capacity calculation means and the outflow heat quantity calculation means, respectively. In the above example, when the air volume is A, the cooling capacity is a-outflow heat amount α, and when the air volume is B, the cooling capacity b-outflow heat amount β is sequentially calculated. The air volume will be selected. The blower is operated at this selected blow rate. For this reason, the cooldown is always performed with the maximum cooling surplus capacity, and the efficiency and time of the cooldown can be shortened.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram showing the periphery of a control device for a refrigerator for a refrigerating vehicle according to the present invention. In the figure, the temperature setting device 15 is for setting the cooling temperature in the luggage compartment 1, and the signal from this is output to the CPU described later as a temperature setting signal. The outside air sensor 16 is a sensor that detects the outside air temperature, and the solar radiation sensor 17 is a sensor that detects the amount of solar radiation to the cold storage vehicle. Both the outlet temperature sensor 18 and the inlet temperature sensor 3 are provided in the cooling unit 2, and the outlet temperature sensor 18 detects the air temperature immediately after being blown through the evaporator 12, and the inlet temperature sensor 3 Is for detecting the air temperature immediately before being sucked into the evaporator 12.

The control device 5 is provided with a CPU 20 which mainly controls the calculation of the amount of air blown in the luggage compartment 1. The CPU 20 is provided with a storage unit 21 for correcting the air volume data in the relationship between the temperature difference between the set temperature and the internal temperature and the outside air temperature and the air volume data according to the amount of solar radiation. The correction data, etc. of are stored. In the drawing, the storage unit 21 is shown as being built in the CPU 20, but it may be connected to the CPU 20 as an independent storage device. Further, in the control device 5, a condenser fan control unit 22, an air flow rate control unit 23, and a compressor control unit 24, which control the operation of an external device based on a signal from the CPU 20, are provided. The condenser fan control unit 22 controls the on / off operation of the capacitor fan 11. The air flow rate control unit 23 controls the rotation speed of the evaporator fan 10 so as to realize the optimum air flow rate calculated by the CPU 20. Since it is preferable that the control of the rotational speed is performed steplessly, the semiconductor control element such as a power transistor controls the current flowing through the fan. The compressor controller 24 controls the compressor 6 to be turned on and off based on the internal temperature detected by the suction temperature sensor 3.

The apparatus having the above configuration operates as follows according to the flowchart shown in FIG. First, when the main power source (not shown) is turned on and the program is activated, the CPU 20 detects the set temperature set by the temperature setter 15 and the outside air sensor 16, the solar radiation sensor 17, the blowout temperature sensor 18, and the suction temperature sensor 3. The outside temperature, the amount of solar radiation, the outlet temperature, and the inside temperature are input (S1). Next, the CPU 20 calculates the temperature deviation ΔT between the set temperature and the internal temperature. By obtaining this temperature difference, the cooling capacity of the refrigerator is assumed (S2). Next, the air volume is calculated based on the detected outside air temperature and the calculated temperature deviation ΔT. The calculation of the air volume is performed based on the air volume data stored in the storage unit 21. The air volume data stored in the storage unit 21 corresponds to a graph as shown in FIG. 3A and is for calculating the air volume based on the temperature deviation and the outside air temperature. As is clear from this figure, even with the same temperature deviation, the higher the outside air temperature, the smaller the air volume. This is because, as shown in the results obtained by the above-mentioned experiment, it is possible to cool the inside of the compartment in a region where the excess capacity is large when the air volume is reduced together with the decrease of the inside temperature. Further, it is assumed that the amount of heat outflow from the inside 1 is based on the inside temperature and the outside air temperature. In the process of calculating the above airflow, the outflow heat amount is also calculated automatically. (S3). Then, the solar radiation correction calculation is performed on the air volume calculated in the above step. That is, the data of the relationship between the amount of solar radiation and the amount of wind as shown in FIG. 3 (B) is stored in the storage unit 21, but in the case of solar radiation, it was further calculated according to the amount. Make a correction to reduce the air volume. This is also because the inside air is cooled in a region with a large surplus capacity by reducing the air volume (S4). In order to realize the optimum air volume calculated in this way, the CPU 20 calculates the voltage to be applied to the evaporator fan 10 and applies the voltage to the air blow rate control unit 23 to the evaporator fan 10. The command is output (S5). The air flow rate control unit 23 applies a voltage based on this command to the evaporator fan 10 to cool the inside of the refrigerator with a predetermined air flow rate (S6).

By performing such an air volume control, it becomes possible to always cool the inside of the refrigerator under the condition that the surplus capacity is maximum. The on / off control of the compressor 6 is turned off at a point where the temperature deviation is a little negative than 0, and is turned on at a point a little more than 0 plus. This control is controlled by the compressor controller 24 based on a command from the CPU 20. Therefore, it is possible to reduce the drive power of the evaporator fan 10 and the drive power of the compressor 6.

In the above embodiment, an example in which the air volume control is performed based on the temperature deviation between the set temperature and the internal temperature has been described, but as shown in FIG. The above air volume control may be performed based on the magnitude of the change rate of the internal temperature. In this case, it goes without saying that the control unit 21 is made to store the data of the relationship between the rate of change, the outside air temperature and the air volume. Even when the control based on the rate of change is performed in this manner, the air volume control that is almost the same as the temperature deviation control can be performed.

[0014]

[Effect of the device]

 As described above, according to the present invention, the inside of the refrigerator is always cooled with the maximum surplus capacity, so that the cooldown can be performed faster and the power consumption of the blower can be reduced. You will be able to save money.

[Brief description of drawings]

FIG. 1 is a block diagram of the periphery of a control device for a refrigerator for cold storage vehicles according to the present invention.

FIG. 2 is an operation flowchart of the apparatus shown in FIG.

3 (A) to 3 (C) are diagrams for explaining a process of calculating an air volume calculated by the control device of FIG. 1.

FIG. 4 is a schematic configuration diagram of a general cold storage vehicle.

5 is a schematic configuration diagram of a cooling system of the cold storage vehicle shown in FIG.

FIG. 6 is a graph showing the relationship between the proportional constant K value of the amount of heat radiated from the container and the air volume by the blower.

FIG. 7 is a graph showing the relationship between the amount of air and the amount of surplus heat under the conditions of an outside air temperature of 35 ° C. and an inside temperature of 10 ° C.

FIG. 8 is a graph showing the relationship between the amount of air and the amount of surplus heat under the conditions of an outside air temperature of 35 ° C. and an inside temperature of 0 ° C.

FIG. 9 is a graph showing the relationship between the amount of air and the amount of surplus heat under the conditions of an outside air temperature of 35 ° C. and an inside temperature of −18 ° C.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Luggage compartment (refrigerator) 2 ... Cooling unit 3 ... Suction temperature sensor 5 ... Control device 6 ... Compressor 7 ... Condenser 9 ... Flow control element 10 ... Evaporator fan (blower) 11 ... Condenser fan 12 ... Evaporator 13 ... Various sensors 20 ... CPU (cooling capacity calculation means, outflow heat amount calculation means,
Blower amount calculating means) 23. Blower amount controlling section (blower amount calculating means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeshi Ogasawara 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonitz Co., Ltd. (72) Shunichi Yamanaka 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonitz Co., Ltd. (72) Creator Yasuhisa Nakahara 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonitz Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. An evaporator for cooling the air in the refrigerating chamber, a blower for circulating the air in the refrigerating chamber through the evaporator, and a cooling for calculating the cooling capacity of the evaporator in relation to the amount of air blown from the blower. A capacity calculating means, an outflow heat amount calculating means for calculating the outflow heat amount from the refrigerating chamber in relation to the air flow rate, and a cooling capacity and an outflow heat amount respectively calculated by the cooling capacity calculating means and the outflow heat amount calculating means. And a blower amount calculating means for calculating a blower amount that maximizes the cooling surplus capacity of the evaporator.