JPH0510972U - Frozen car - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the cooldown performance in the freezer and the durability of the compressor when the heat load is large. [Structure] The motor speed of a blower (5) that guides the air in the freezer (1) to an evaporator (3) depends on environmental conditions such as the temperature (t) in the freezer or the refrigerant pressure (P) at the evaporator outlet of the refrigeration cycle. When the heat load in the freezer is equal to or higher than a predetermined value, the motor rotation speed is reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a refrigerating vehicle for transporting a frozen product such as a frozen product, a chilled product, and a cool product to a destination while keeping it cooled, and particularly, to enhance the durability of a compressor caused by a change in heat load. ..

[0002]

[Prior Art]

 The cold-required products can be roughly classified into three types: frozen products held at around -20 ° C, chilled products held at around 0 ° C, and cool products held at around 10 ° C. A refrigerating vehicle equipped with a freezer and a cooling device is known as a means for transporting a large amount of such a substance to be cooled to a destination. For example, a refrigeration vehicle disclosed in Japanese Patent Laid-Open No. 62-210,373 has a cooling unit, which is configured by a fan motor attached to the back surface of an evaporator for sending air in the freezer, provided in the freezer. During cooling, the cooling unit is installed so that the fan motor is housed in a substantially triangular space formed by the front and side walls of the freezer and the evaporator. In addition, the refrigeration vehicle disclosed in Japanese Patent Laid-Open No. 62-112,977 has a freezer inside for freezing in order to transport a plurality of items requiring cooling such as frozen products, chilled products and cool products having different control temperatures. It is divided into multiple small rooms by partition walls, and the control temperatures of each small room are different.

A cooling device mounted on such a refrigeration vehicle has a refrigeration cycle including a compressor, a condenser, a liquid tank, an expansion valve, and an evaporator. It looks like. In other words, refrigerants such as chlorofluorocarbon that are easily liquefied are adiabatically compressed by the compressor to become high-temperature and high-pressure gas refrigerant, and then condensed by being cooled by the condenser, and a part of this liquid refrigerant is stored in the liquid tank. To be done. Then, this high-pressure liquid refrigerant is adiabatically expanded by the expansion valve to become a low-temperature low-pressure liquid refrigerant, and finally heat-exchanged in the evaporator to be vaporized and become a gas refrigerant.

[0004]

[Problems to be solved by the device]

 By the way, when the heat load is large, such as when the outside air temperature or the freezer temperature is high, the refrigerant discharge temperature and discharge pressure of the compressor rise, which adversely affects the durability of the compressor.Therefore, the refrigerant pressure is detected in the liquid tank. A pressure switch was provided to protect the compressor by disengaging the magnet clutch of the compressor when the refrigerant pressure in the cooling cycle rises above a certain level.

However, in a cooling device used for a refrigerating vehicle, it is necessary to cool the inside of the freezer to around −20 ° C. like a frozen product, so that the refrigerant pressure inside the refrigeration cycle becomes extremely high, and particularly the cooling is performed. Immediately after the equipment was started at high speeds, it took a long time to reach the desired temperature because the pressure switch installed in the liquid tank often worked. The present invention has been made in view of the above problems of the conventional technology, and an object thereof is to improve the cooldown performance in the freezer and the durability of the compressor when the heat load is large.

[0006]

[Means for Solving the Problems]

 Means for Solving the Problems The present invention for achieving the above object is to introduce air in the freezer (1) into a freezer (1) that stores a substance to be cooled and an evaporator (3) that constitutes a refrigeration cycle (2). In a refrigerating vehicle having a cooling device (4) for cooling the inside to a predetermined temperature, the motor speed of a blower (5) for guiding the air in the freezer (1) to the evaporator (3) is set to the freezer. When the heat load in the freezer is determined to be equal to or higher than a predetermined value due to environmental conditions such as the internal temperature (t) or the refrigerant pressure (P) at the evaporator outlet of the refrigeration cycle, it is possible to reduce the motor speed of the blower. It is a characteristic freezing wheel.

[0007]

[Action]

 In general, the heat load Q of a refrigerating vehicle is given by: Q when the body flow rate K, the heat transfer area F of the body, the body internal volume VB, the outside air temperature ta, the set temperature tr in the refrigerator, and the door service constant c. = 1.2KF (ta-tr) + c (0.54VB + 3.22) (ta-tr). Here, the K value was generally determined only by the type and thickness of the heat insulating material of the freezer, and was conventionally thought to be unrelated to other factors. However, according to what the inventors of the present invention have sought, This K value is almost proportional to the air volume passing through the evaporator. Therefore, it was revealed that reducing the air volume also decreases the K value, and as a result, the heat load Q on the refrigeration vehicle becomes smaller. Therefore, in the present invention, when it is determined that the heat load in the freezer is large due to environmental conditions such as the temperature in the freezer or the refrigerant pressure in the refrigeration cycle, the air volume of the blower is reduced to The internal heat load is reduced, and as a result the inside of the freezer is cooled to a specified temperature.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is a perspective view showing a refrigerating vehicle according to an embodiment of the present invention, FIG. 2 is a conceptual view showing a cooling device according to the same embodiment, FIG. 3 is a flow chart showing the operation of the embodiment, and FIG. FIG. 5 is a graph showing the relationship between the air flow rate of the cooling device and the coefficient of thermal inertia of the freezer, showing the operation of another embodiment of the idea.

The refrigerating vehicle according to the present embodiment has a driver's cab 6 and a freezer 1. The freezer 1 is divided into a plurality of small chambers by partition walls, and each of the small chambers is provided with a cooling device 4 described later. You can also In addition, a plurality of shelves may be provided in the freezer 1 to enhance the efficiency of storing and unloading the items requiring cooling. On the other hand, a door 7 is provided on the rear wall of the freezer 1 to facilitate the loading and unloading work of the items requiring cooling.

The cooling device 4 according to the present embodiment includes a compressor 8 which is provided in a lower portion of a driver's cab 6 and driven by a vehicle running engine or a vehicle-mounted auxiliary engine (neither is shown) and a bottom of the freezer 1. The refrigeration cycle 2 is configured by connecting the provided condenser 9 and the evaporator 3 mounted in the freezer 1 in a closed circuit through a refrigerant pipe 10. The evaporator 3 is housed in a cooling unit 11, and a blower 5 for sucking the air in the freezer 1 to pass it through the evaporator 3 and then blowing the air into the freezer 1 again is provided on the downstream side thereof. Has been. Then, the refrigerant is circulated in the refrigeration cycle 2 by the compressor 3, and the gas refrigerant that has become high temperature and high pressure by the compressor 8 is condensed by being cooled by the condenser 9, and a part of this liquid refrigerant is stored in the liquid tank 12. At the same time, it is adiabatically expanded by the expansion valve 13 to form a low-temperature low-pressure atomized refrigerant, and finally heat is exchanged by the evaporator 3 to cool the air in the freezer 1.

Particularly, in the cooling device 4 of the present embodiment, the temperature sensor 14 for detecting the temperature in the freezer 1 is provided, and the information of the temperature sensor 14 is input to the control means 15 and the information is Based on this, the motor speed of the blower 5 is controlled. Specifically, when the heat load on the cooling device 4 is large, that is, when the temperature inside the freezer 1 is high, the motor speed of the blower 5 is reduced.

Next, the operation will be described. When the cooling device 4 of the refrigeration vehicle is operated, the magnetic clutch of the compressor 8 is connected to circulate the refrigerant in the refrigeration cycle 2 by the compressor 8 and the blower 5 is operated to cool the air in the freezer 1 to the cooling unit 11 Circulate inside. Then, the gas refrigerant that has become high temperature and high pressure by the compressor 8 is cooled and condensed by the condenser 9, and a part of this liquid refrigerant is stored in the liquid tank 12 and adiabatically expanded by the expansion valve 13 to form a low temperature and low pressure mist. It becomes a refrigerant, and finally it is heat-exchanged with the air inside the freezer in the evaporator 3, whereby the temperature of the air inside the freezer 1 gradually begins to drop. At this time, if the temperature t in the freezer is equal to or higher than the predetermined temperature T0, this is input from the temperature sensor 14 to the control means 15 for determination, and a low speed drive signal is output to the blower 5. This is for the following reason. That is, the heat load Q of the refrigerating vehicle is given as follows: when the body's inertial flow rate K, body heat transfer area F, body volume VB, outside air temperature ta, inside storage temperature tr, and door service constant c are set. It is expressed by Q = 1.2KF (ta-tr) + c (0.54VB + 3.22) (ta-tr), and the K value is generally determined only by the type and thickness of the heat insulating material, and is not related to other factors. Was considered a thing. However, according to what the inventors of the present invention have sought, it has been found that this K value has the relationship shown in FIG. 5 with the air volume passing through the evaporator. That is, according to the experimental results shown in FIG. 5, the air volume passing through the evaporator and the K value are in a substantially proportional relationship, and therefore, when the air volume is reduced, the K value also decreases, and as a result, the heat load Q Became smaller. Therefore, when it is determined that the heat load is large due to the temperature in the freezer 1, the air flow rate of the blower 5 is reduced to reduce the heat load in the freezer 1 and, as a result, the inside of the freezer 1 is set to a predetermined level. Cool to temperature.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified. For example, in the above-described embodiment, the heat load in the freezer 1 is determined by the temperature (temperature sensor 14) in the freezer 1, but the heat load in the freezer 1 is determined by the pressure of the refrigerant circulating in the refrigeration cycle 2. It may be configured to do so. Specifically, a pressure sensor (not shown) is attached to the evaporator outlet side of the refrigeration cycle 2, this information is input to the control means 15, and as shown in FIG. 4, this refrigerant pressure P is a predetermined value P 0 or more. Then, a low speed drive signal is output to the blower 5 to reduce the amount of air passing through the evaporator 3.

[0014]

[Effect of the device]

 As described above, according to the present invention, the motor speed of the blower that guides the air in the freezer to the evaporator is controlled by the environmental conditions such as the temperature in the freezer or the refrigerant pressure at the evaporator outlet of the refrigeration cycle. When the heat load in the freezer is higher than a predetermined value, the motor rotation speed is reduced.Therefore, the heat load in the freezer is reduced by reducing the air volume passing through the evaporator. The interior can be efficiently cooled, and as a result, it is possible to prevent the durability of the compressor from being deteriorated due to the rise of the refrigerant pressure.

[Brief description of drawings]

FIG. 1 is a perspective view showing a refrigeration vehicle according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a cooling device according to the embodiment.

FIG. 3 is a flowchart showing the operation of the same embodiment.

FIG. 4 is a flow chart showing the operation of another embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the air flow rate of the cooling device and the heat flow coefficient of the freezer.

[Explanation of symbols]

1 ... Freezer, 2 ... Refrigeration cycle, 3 ... Evaporator, 4 ... Cooling device, 5 ... Blower,
t ... Temperature in freezer, P ... Refrigerant pressure at evaporator outlet of refrigeration cycle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tsunemi Ikeda 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonitz Co., Ltd. (72) Kotaro Ohashi 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonitz Co., Ltd. (72) Creator Koichi Umemoto 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic Co., Ltd.

Claims (1)

[Claims for utility model registration] [Claim 1] A freezer (1) for storing a substance to be cooled, and an evaporator (3) constituting a refrigeration cycle (2) by guiding air in the freezer (1) to the freezer. (1) A refrigeration vehicle having a cooling device (4) for cooling the inside to a predetermined temperature,
The rotation speed of the motor of the blower (5) that guides the air in the freezer (1) to the evaporator (3) is controlled by environmental conditions such as the temperature (t) in the freezer or the refrigerant pressure (P) at the evaporator outlet of the refrigeration cycle. A refrigerating vehicle, wherein the motor rotation speed of the blower is reduced when it is determined that the heat load therein is a predetermined value or more.