KR20110034256A - Co2 air-conditioning system - Google Patents

Abstract

PURPOSE: A carbon dioxide air-conditioning system is provided to rapidly heat refrigerant for heating by an improved refrigerant circulating path. CONSTITUTION: A carbon dioxide air-conditioning system comprise a compressor(400), an evaporator(500), a first gas cooler(110), a second gas cooler(120), a sub heat-exchanger(810), a supplementary heat source(800), an internal heat exchanger(200), a first bypass valve(710), and a second bypass valve(720). The first and the second gas coolers selectively exchange heat between the refrigerant and air according to the mode of the first and the second gas coolers. The sub heat-exchanger is parallel in the first gas cooler. The refrigerant passing through a second expansion valve(620) is evaporated by the sub heat-exchanger. The supplementary heat source supplies the heat to the sub heat-exchanger. The internal heat exchanger exchanges heat between the refrigerant of the low temperature and low pressure discharged from the evaporator and the refrigerant of high temperature and high pressure discharged from the first gas cooler.

Description

CO2 Air-Conditioning System

The present invention relates to a carbon dioxide air conditioning system, and more particularly, to a carbon dioxide air conditioning system having an improved heat pump cycle.

In the reality that the pollution problem of the environment is getting serious due to the development of civilization, regulations on the use of refrigerant materials that destroy the earth's ozone layer, such as CFC refrigerants, are spreading. Developed as a refrigerant material to replace Freon gas (R-12, CFC refrigerant), R-134a (CFC refrigerant), unlike R-12, does not form chlorine atoms, which is the main cause of destroying the ozone layer. Although it has a stable molecular structure that does not react and does not have toxicity and flammability, there is a problem that the freezing ability is deteriorated at the condensation temperature such as R-12, and it also completely solves the problem of R-12 in that it causes a greenhouse effect. I can't think of a solution. In general, most of the refrigerant materials currently used in the air conditioning system of the vehicle are CFC-based refrigerants, but as environmental concerns are growing, many restrictions are placed on these materials, and thus, there is a sufficient replacement capacity and a safe replacement. Research on refrigerants has been conducted steadily.

One of the substances that emerged as an alternative refrigerant according to this current is carbon dioxide (CO ₂ ). Originally, carbon dioxide has been used as a refrigerant material before CFC-based refrigerants have been used. However, carbon dioxide has not been used due to problems such as high compression and low energy efficiency. However, nowadays, research and development of vehicle air conditioners using carbon dioxide as a refrigerant has been accelerated not only due to the development of compression technology but also due to the great advantage of not causing environmental problems.

On the other hand, vehicles driven by engines using gasoline, diesel, etc. as the energy source are the most common types of vehicles at present, but these energy sources for vehicles are also used due to various causes such as the reduction of oil reserves as well as environmental pollution. As the necessity arises, one of the technologies closest to the current practical use is a vehicle driven by a fuel cell as an energy source. However, in a vehicle using such a fuel cell, unlike a vehicle having an engine using petroleum as an energy source, a heating system using cooling water cannot be used. In this case, when a cooling system using a carbon dioxide refrigerant is used as an air conditioning system of such a fuel cell vehicle, a heat pump may be added to the carbon dioxide air conditioning system and used as a heat source.

1 is a system diagram of a conventional carbon dioxide air conditioning system according to the prior art, Figures 2a to 2c shows a refrigerant circulation path in the cooling / heating / dehumidification mode in the general carbon dioxide air conditioning system shown in FIG.

During cooling, as shown in FIG. 2A, the refrigerant may include a first gas cooler 1110, a first flow path 1210 of the internal heat exchanger 1200, a first expansion valve 1611, an evaporator 1500, and an accumulator 1300. The second passage 1220, the compressor 1400, the second gas cooler 1120, and the second bypass valve 1622 of the internal heat exchanger 1200 are sequentially circulated. That is, the refrigerant expands while passing through the first expansion valve 1611 and passes through the evaporator 1500 to cool the air around the evaporator 1500. When the wind is generated by the blower fan, the cooled air is blown around the evaporator 1500, thereby discharging the cooled air to the inside of the vehicle.

In the heating, as shown in FIG. 2B, the refrigerant may include a first gas cooler 1110, a first flow path 1210 of the internal heat exchanger 1200, a first bypass valve 1612, an accumulator 1300, and an internal heat exchanger. The second passage 1220, the compressor 1400, the second gas cooler 1120, and the second expansion valve 1621 of 1200 are sequentially circulated. That is, the refrigerant is compressed while passing through the compressor 1400, then passes through the second gas cooler 1120, and then expands while passing through the second expansion valve 1621. At this time, the second gas cooler 1120 corresponds to the location of the condenser, but the phase change of the refrigerant does not actually occur. However, the second gas cooler 1120 emits heat to the surrounding air, thereby discharging the heated air to the inside of the vehicle.

During the dehumidification, as shown in FIG. 2C, the refrigerant may include a first gas cooler 1110-a first flow passage 1210 of the internal heat exchanger 1200-a first expansion valve 1611-an evaporator 1500-an accumulator. The circuit 1300 is circulated through the second passage 1220 of the internal heat exchanger 1200, the compressor 1400, the second gas cooler 1120, and the second expansion valve 1621. In other words, the refrigerant passes through the evaporator 1500 to cool the surrounding air. At this time, moisture in the air is liquefied to dry the air. In addition, the refrigerant passes through the second gas cooler 1120 to release heat to the surrounding air, and the air dried by passing through the evaporator 1500 is heated by the heat emitted from the second gas cooler 1120. do. Therefore, dehumidified and heated air is discharged inside the vehicle.

As illustrated in FIGS. 2A to 2C, a conventional carbon dioxide air conditioning system uses a plurality of bypass valves to switch cooling / heating / dehumidification modes, and also a plurality of expansion valves in accordance with a refrigerant circulation path that changes depending on the mode. Equipped with. In particular, in the heating or dehumidification mode, a heat pump system for heating or dehumidifying using heat emitted by the second gas cooler 1120 is achieved.

However, the conventional carbon dioxide air conditioning system had various problems. FIG. 3 is a graph illustrating various characteristics of a conventional carbon dioxide air conditioning system in a cryogenic environment (ambient temperature -6 ° C.), an idling state, and a heating mode. In FIG. 3, A represents a temperature of the refrigerant discharged from the compressor 1400, and B represents a temperature of air after passing through the second gas cooler 1120. Referring to FIG. 2B, the refrigerant discharged from the compressor 1400 dissipates heat to the surroundings while passing through the second gas cooler 1120, whereby air passing through the second gas cooler 1120 It is heated to heat the inside of the vehicle.

However, first, when the temperature of the refrigerant discharged from the compressor 1400 changes over time (A graph), even if the heating mode is started after about 10 minutes (600 seconds) after starting the engine, the temperature of the refrigerant It can be seen that the increase rate is very slow, reaching high temperatures only about 23 minutes (1400 seconds). Since the refrigerant discharged from the compressor 1400 heats the air while passing through the second gas cooler 1120, the air will not be heated well unless the refrigerant discharged from the compressor 1400 is sufficiently high. Of course. This is shown in the aspect (B graph) in which the temperature of the air passing through the second gas cooler 1120 changes with time (graph B), but it is found that the change is smaller than that of the refrigerant temperature. Can be. Practically speaking, even if the air conditioning system is operated in the heating mode, that is, even if it starts heating after 10 minutes of starting the engine, it must be about 13 minutes before the air temperature from the air conditioning system reaches about 50 ° C. The temperature is reached enough to heat the inside of the vehicle.

As described above, when the carbon dioxide air conditioning system is operated in the heating mode in the cryogenic state, it takes a very long time to start the actual heating, which causes a great inconvenience for the user. In addition, systemically, the temperature of the refrigerant does not increase well, so that the cryogenic refrigerant flows in the system for a while after the start. Thus, the cryogenic refrigerant has a high viscosity, which lowers the liquidity of the refrigerant. There was this. Due to this problem, the slugging phenomenon and the degree of superheat in the compressor 1400 are increased. Therefore, not only the operation efficiency of the compressor 1400 is lowered, but also the damage or breakage of the compressor 1400 is increased. There was also a growing problem of risk.

In addition, in the case of the conventional carbon dioxide air conditioning system there is a problem that there is a problem that the moisture is not removed when switching from the cooling mode to the heating mode, such as steaming inside the vehicle, there are various problems.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is not to use a first gas cooler as an evaporator in a heating mode (ie when using a heat pump system) and to provide an auxiliary heat source. By using the, it is to provide a carbon dioxide air conditioning system that ensures the coolant fluidity in all operating areas by allowing the heating in the cryogenic state more effectively, thereby maximizing the system efficiency.

Carbon dioxide air conditioning system according to the present invention for achieving the above object, the compressor 400 for compressing the refrigerant; An evaporator 500 for evaporating the refrigerant passing through the first expansion valve 610 in the cooling mode; A first gas cooler 110 and a second gas cooler 120 configured to selectively heat the refrigerant introduced therein according to the mode to exchange heat with air; An auxiliary heat exchanger 810 disposed in parallel with the first gas cooler 110 to evaporate the refrigerant passing through the second expansion valve 620 in a heating mode; An auxiliary heat source 800 for supplying heat to the auxiliary heat exchanger 810; The first flow path 210 and the second flow path 220 in which the low temperature / low pressure refrigerant discharged from the evaporator 500 and the high temperature / high pressure refrigerant discharged from the first gas cooler 110 are closely connected to each other in the cooling mode. Internal heat exchanger 200 for mutual heat exchange by circulating through each; A first bypass valve 710 and a second bypass valve 720 for switching a circulation path of the refrigerant in the cooling mode and the heating mode; And the first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to one selected from the first gas cooler 110 and the auxiliary heat exchanger 810. The second bypass valve 720 distributes the refrigerant flowing from one selected from the internal heat exchanger 200 and the auxiliary heat exchanger 810 to the compressor 400, and the first bypass valve ( 710 and the coolant may be circulated through any one path selected from a cooling mode refrigerant circulation path and a heating mode refrigerant circulation path formed by the selection of the open flow path of the second bypass valve 720.

At this time, the cooling mode refrigerant circulation path, the first bypass valve 710 flows the refrigerant flowing from the second gas cooler 120 side to the first gas cooler 110, the second by The pass valve 720 is formed by circulating the refrigerant flowing from the internal heat exchanger 200 toward the compressor 400, and the refrigerant flowing from the compressor 400 passes through the second gas cooler 120. Passes through the first gas cooler 110 through the first bypass valve 710, passes through the second flow path 220 of the internal heat exchanger 200, and expands while passing through the first expansion valve 610. Thereafter, the evaporator 500 passes through the evaporator 500 to cool the air, and flows into the compressor 400 through the first flow path 210 and the second bypass valve 720 of the internal heat exchanger 200. It is characterized by.

In addition, the heating mode refrigerant circulation path, the first bypass valve 710 flows the refrigerant flowing from the second gas cooler 120 side to the auxiliary heat exchanger 810, the second bypass valve A 720 is formed by circulating the refrigerant flowing from the auxiliary heat exchanger 810 to the compressor 400, and the refrigerant flowing from the compressor 400 heats air while passing through the second gas cooler 120. And expands while passing through the first expansion valve 710 and passes through the second expansion valve 620, and then evaporates while passing through the auxiliary heat exchanger 810, and the second bypass valve 720. Passing through the compressor 400 is characterized in that the.

In addition, the auxiliary heat source 800 is characterized by being formed of any one or more selected from an electric heater, a warmer using cooling water, a heat pump heat exchanger using a refrigerant.

In addition, the evaporator 500 and the second gas cooler 120 are provided in the air flow path 900 introduced into the vehicle, and the second gas cooler 120 is provided downstream of the evaporator 500. It is characterized by. At this time, the air flow path 900 allows the air passing only the evaporator 500 to be introduced into the vehicle, or the air passing through the evaporator 500 and the second gas cooler 120 sequentially It is characterized in that it comprises a ventilation opening and closing door 910 for switching the air flow to be introduced into the vehicle.

In addition, the carbon dioxide air conditioning system includes a gas-liquid separator 300 for gas-liquid separating the refrigerant flowing into the compressor 400 to introduce only the liquid refrigerant into the compressor 400; It is preferred to further comprise a.

In addition, the carbon dioxide air conditioning system control method according to the present invention, in the carbon dioxide air conditioning system control method using the carbon dioxide air conditioning system as described above, a1) a cooling mode is selected; a2) the first bypass valve 710 switches the flow path so as to distribute the refrigerant to the first gas cooler 110, and the second bypass valve 720 receives the refrigerant from the internal heat exchanger 200; Converting the flow path for circulation; a3) arranging the air opening and closing door 910 such that air passing only the evaporator 500 flows into the vehicle; Characterized in that comprises a.

In addition, the carbon dioxide air conditioning system control method according to the present invention, the carbon dioxide air conditioning system control method using the carbon dioxide air conditioning system as described above, b1) a dehumidification mode is selected; b2) When the outside temperature T _ambient is lower than the preset outside air reference temperature K _a (K _a <T _ambient : No), a dehumidification heating mode is set, and the first bypass valve 710 is configured to exchange the auxiliary heat. The flow path is switched so as to distribute the refrigerant to the air 810 side, the second bypass valve 720 switches the flow path so as to distribute the refrigerant from the auxiliary heat exchanger 810, and the preset outside air reference temperature K _{When the} ambient temperature (T _ambient ) is higher than ( _a ) (K _a <T _ambient : Yes), the dehumidification cooling mode is set, and the first bypass valve 710 distributes the refrigerant to the first gas cooler 110. Switching the flow path so that the flow path is turned on, and switching the flow path so that the second bypass valve 720 circulates the refrigerant from the internal heat exchanger; b3) When the dehumidification cooling mode is set in the step b2), when the preset reference temperature T _setting is lower than the vehicle internal temperature T _int (T _int <T _setting : No), the ventilation opening and closing door 910 is When the air passing only the evaporator 500 is disposed to flow into the vehicle, and the preset reference temperature T _setting is higher than the vehicle internal temperature T _int (T _int <T _setting : Yes), the ventilation opening and closing door 910 ) Is arranged such that air sequentially passing through the evaporator (500) and the second gas cooler (120) flows into the vehicle; Characterized in that comprises a.

In addition, the carbon dioxide air conditioning system control method according to the present invention, the carbon dioxide air conditioning system control method using the carbon dioxide air conditioning system as described above, c1) the heating mode is selected; c2) When the _ambient air temperature T _ambient is higher than _a preset outside air reference temperature K _a (K _a <T _ambient : Yes), the first bypass valve 710 is set to a general heating mode, so that the first heat exchange The flow path is switched to circulate the refrigerant to the air 810, the second bypass valve 720 switches the flow path to circulate the refrigerant from the auxiliary heat exchanger 810, and the first gas cooler 110. ) and the air flow into the auxiliary heat exchanger (810) is opened, when the lower the outdoor temperature (T _ambient) than the ambient reference temperature (K _a) previously set (K _a <T _ambient: No), is set to a low temperature heating mode Comparing the preset refrigerant reference temperature K _c with the refrigerant temperature T _coolant ; c3) When the low temperature heating mode is set in step c2), when the coolant temperature T _coolant is higher than the preset coolant reference temperature K _c (K _c <T _coolant : Yes), the first bypass valve 710 ) Converts the flow path to circulate the refrigerant to the auxiliary heat exchanger 810 side, the second bypass valve 720 switches the flow path to circulate the refrigerant from the auxiliary heat exchanger 810, and When the air flow to the first gas cooler 110 and the auxiliary heat exchanger 810 is closed, and the refrigerant temperature T _coolant is lower than the preset refrigerant reference temperature K _c (K _c <T _coolant : No) In the cryogenic heating mode, the first bypass valve 710 switches the flow path so as to distribute the coolant to the auxiliary heat exchanger 810, and the second bypass valve 720 converts the auxiliary heat exchanger ( The flow path is switched to circulate the refrigerant from 810, and the first gas cooler ( 110) and the air circulation to the subsidiary heat exchanger 810 is closed, and the subsidiary heat source 800 is operated to supply heat to the subsidiary heat exchanger 810; c4) When the cryogenic heating mode is set in step c3), when the compressor inlet refrigerant temperature T _{ref_suc} is lower than the preset compressor inlet refrigerant reference temperature K _s (K _s <T _{ref_suc} : No), the auxiliary heat source ( Performing the operation of 800 repeatedly, and when the compressor inlet refrigerant temperature T _{ref_suc} is higher than the preset compressor inlet refrigerant reference temperature K _s (K _s <T _{ref_suc} : Yes), the process proceeds to the next step; c5) the compressor 400 starts to operate; c6) arranging the air opening and closing door 910 such that air sequentially passing through the evaporator 500 and the second gas cooler 120 flows into the vehicle; Characterized in that comprises a.

According to the present invention, the conventional carbon dioxide air conditioning system has a great effect of solving the problem that the heating is made very slowly because the refrigerant is not heated quickly in the cryogenic environment. That is, in the present invention, by improving the refrigerant circulation path of the carbon dioxide air conditioning system so as not to use the first gas cooler as the evaporator in the heating mode and to use the auxiliary heat source, the refrigerant is heated faster and the heating is made faster. It works.

As described above, according to the present invention, a rapid heating is performed in a cryogenic environment, such as winter, which has a great effect of maximizing user convenience, and also solves a problem of exerting a compressor on the compressor by flowing a refrigerant having a high viscosity in a low temperature state. There is also an effect. This, of course, not only improves the efficiency of the air conditioning system, but also has the effect of extending durability and life.

In particular, according to the present invention, even in the case of heating, a more efficient mode is selected and operated according to the ambient temperature, that is, at a cryogenic state or at a normal temperature state, regardless of environmental variables such as ambient temperature, system efficiency and heating effect. There is a big effect that can be maximized.

Hereinafter, a carbon dioxide air conditioning system according to the present invention having the configuration as described above will be described in detail with reference to the accompanying drawings.

Figure 4 shows a carbon dioxide air conditioning system according to the present invention. Carbon dioxide air conditioning system according to the present invention, as shown, the compressor 400 for compressing the refrigerant; An evaporator 500 for evaporating the refrigerant passing through the first expansion valve 610 in the cooling mode; A first gas cooler 110 and a second gas cooler 120 configured to selectively heat the refrigerant introduced therein according to the mode to exchange heat with air; An auxiliary heat exchanger 810 disposed in parallel with the first gas cooler 110 to evaporate the refrigerant passing through the second expansion valve 620 in a heating mode; An auxiliary heat source 800 for supplying heat to the auxiliary heat exchanger 810; The first flow path 210 and the second flow path 220 in which the low temperature / low pressure refrigerant discharged from the evaporator 500 and the high temperature / high pressure refrigerant discharged from the first gas cooler 110 are closely connected to each other in the cooling mode. Internal heat exchanger 200 for mutual heat exchange by circulating through each; A first bypass valve 710 and a second bypass valve 720 for switching a circulation path of the refrigerant in the cooling mode and the heating mode; It is made, including. In this case, the first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to one selected from the first gas cooler 110 and the auxiliary heat exchanger 810. The second bypass valve 720 circulates the refrigerant flowing from one selected from the internal heat exchanger 200 and the auxiliary heat exchanger 810 to the compressor 400, wherein the first bypass valve 710 and The refrigerant may be circulated through any one path selected from a cooling mode refrigerant circulation path and a heating mode refrigerant circulation path formed by the selection of the open flow path of the second bypass valve 720. That is, by setting the refrigerant circulation path by the first bypass valve 710 and the second bypass valve 720, a mode such as cooling / heating is set.

At this time, the evaporator 500 and the second gas cooler 120 is provided in the air flow path 900 flowing into the vehicle as shown, the second gas cooler 120 is the evaporator ( Downstream of 500). In addition, the air flow path 900 allows the air passing only the evaporator 500 to be introduced into the vehicle, or the air sequentially passing through the evaporator 500 and the second gas cooler 120 is a vehicle. Ventilated opening and closing door 910 for switching the air flow to be introduced into the interior is provided. Modes such as heating / cooling / dehumidification are determined according to the opening and closing arrangement of the ventilation opening and closing door 910 together with the refrigerant circulation path.

In addition, the carbon dioxide air conditioning system of the present invention, as shown in the gas-liquid separator for introducing only the liquid refrigerant to the compressor 400 by gas-liquid separation of the refrigerant flowing into the compressor 400 to further improve the system efficiency ( It is preferred to further comprise 300).

5A to 5D show refrigerant circulation paths in each mode of the carbon dioxide air conditioning system according to the present invention. Hereinafter, the refrigerant circulation path in each mode will be described in more detail.

First, FIG. 5A illustrates a refrigerant circulation path in the cooling mode, and FIG. 5B illustrates a refrigerant circulation path in the dehumidification mode. In the two modes, the refrigerant circulation path is the same, but the arrangement of the ventilation opening and closing door 910 is different. First, the refrigerant circulation path will be described.

In the carbon dioxide air conditioning system of the present invention, the cooling mode refrigerant circulation path is configured such that the first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to the first gas cooler 110. The second bypass valve 720 is formed by circulating the refrigerant flowing from the internal heat exchanger 200 to the compressor 400. That is, in the cooling mode, the refrigerant is not distributed to the auxiliary heat exchanger 810.

The flow of the refrigerant will be described sequentially as follows. The refrigerant flowing from the compressor 400 passes through the second gas cooler 120, passes through the first gas cooler 110 through the first bypass valve 710, and passes through the internal heat exchanger 200. And expands while passing through the second flow path 220 of the first flow valve 610, and then evaporates while passing through the evaporator 500 to cool air, and the first flow path of the internal heat exchanger 200. Passed through the 210 and the second bypass valve 720 to the compressor 400 is to be circulated. That is, at this time, both the second gas cooler 120 and the first gas cooler 110 correspond to the condenser position, but the phase change of the refrigerant does not actually occur, except that the first gas cooler 110 is moved to the outside. The heat is released and the temperature of the coolant is lowered, and in the second gas cooler 120, the phase change or the heat exchange of the coolant does not occur (since heat does not occur because air does not pass through the surroundings).

At this time, in the cooling mode, as shown in FIG. 5A, the air opening / closing door 910 blocks the second gas cooler 120 so that only the air passing through the evaporator 500 passes through the air flow path 910. It is arranged to flow. Therefore, the wind generated by the rotation of the fan provided in the evaporator 500 flows through the evaporator 500 to the air flow path 900, thereby being cooled by the evaporator 500 inside the vehicle. Air flows in to cool the room.

In the dehumidification mode, as shown in FIG. 5B, the air opening / closing door 910 is arranged to allow the air passing through the evaporator 500 and the second gas cooler 120 to be introduced into the vehicle. . Therefore, after the air is cooled while passing through the evaporator 500 to remove moisture, the air is heated while passing through the second gas cooler 120 for releasing heat to the outside to become an appropriate temperature, and then the air flow path 910. By flowing to), dehumidification can be performed while maintaining the inside of the vehicle at an appropriate temperature.

First, FIG. 5C illustrates a refrigerant circulation path in the heating mode, and FIG. 5B illustrates a refrigerant circulation path in the cryogenic heating mode. In the two modes, the refrigerant circulation path is the same, but the arrangement of the ventilation opening and closing door 910 is different. First, the refrigerant circulation path will be described.

In the carbon dioxide air conditioning system of the present invention, the heating mode refrigerant circulation path is configured such that the first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to the auxiliary heat exchanger 810. The two bypass valve 720 is formed by circulating the refrigerant flowing from the auxiliary heat exchanger 810 to the compressor 400. That is, in the heating mode, the refrigerant is distributed to the auxiliary heat exchanger 810, and the refrigerant is not distributed to the first gas cooler 110 and the internal heat exchanger 200. The first gas cooler 110 is generally located at the outermost side of the vehicle to directly contact external air. In the carbon dioxide air conditioning system of the present invention, the first gas makes direct contact with the external air in a low temperature state in a heating mode. By preventing the coolant from being distributed to the cooler 110, the coolant 110 may increase the temperature of the coolant more quickly.

The flow of the refrigerant will be described sequentially as follows. The refrigerant flowing from the compressor 400 heats air while passing through the second gas cooler 120 and expands while passing through the second expansion valve 620 through the first bypass valve 710. Thereafter, the vaporization is evaporated while passing through the auxiliary heat exchanger 810, and is circulated by passing through the second bypass valve 720 and entering the compressor 400. In this case, the second gas cooler 120 serves as a condenser, and the auxiliary heat exchanger 810 serves as an evaporator. Of course, even in this case, the second gas cooler 120 corresponds to the condenser position, but the phase change of the refrigerant does not actually occur, but only emits heat to the surroundings.

In addition, in the heating mode, the air opening and closing door 910 is disposed such that air sequentially passing through the evaporator 500 and the second gas cooler 120 may be introduced into the vehicle. At this time, since the refrigerant does not flow into the evaporator 500 and no heat exchange occurs, the air is only heated by the second gas cooler 120, and thus, warm air flows into the vehicle, thereby heating. You lose.

However, at this time, the carbon dioxide air conditioning system of the present invention distinguishes between the case where the outside temperature is low temperature and the cryogenic temperature, and further supplies heat to the auxiliary heat exchanger 810 when the outside temperature is cryogenic (for example, below zero). By providing the auxiliary heat source 800, the refrigerant can reach a higher temperature faster. Therefore, the fluidity of the refrigerant can be improved faster, the problem of increasing the slugging and superheating degree in the compressor 400 is solved, and the system efficiency is improved.

As described above, the auxiliary heat source 800 may be formed of any one or more selected from an electric heater, a warmer using cooling water, and a heat pump heat exchanger using a refrigerant. As shown, the auxiliary heat source 800 is an independent part of the rest of the air conditioning system, and only needs to supply heat to the auxiliary heat exchanger 810. It may be formed in any form. That is, the auxiliary heat source 800 may be formed in the form of an electric heater, completely independent of the remaining components. Alternatively, the auxiliary heat source 800 may be formed as part of an air conditioning system. For example, the auxiliary heat source 800 may be configured as a heat pump using a cooling water or a heat pump using a refrigerant. Of course, the auxiliary heat source 800 may be formed in any form as long as it can supply heat to the auxiliary heat exchanger 810, such as a combination of an electric heater and a warmer.

Thus, by having a wide degree of freedom in the form of the auxiliary heat source 800 has the following advantages. If the heating is necessary but not the cryogenic environment, i.e., the outside air temperature is about 0 to 10 ° C, the auxiliary heat source 800 may be more efficient as part of an air conditioning system (ie, a warmer or a heat pump heat exchanger). This is good. However, when the cryogenic environment, that is, the outside air temperature is about -20 ° C, the auxiliary heat source 800 is in the form of an electric heater is more efficient. That is, in the case of the present invention, by configuring the auxiliary heat source 800 in a complex manner to operate a heat source in a more advantageous form according to the outside temperature, it is possible to improve the system efficiency and effectively raise the temperature of the refrigerant.

6a and 6b are embodiments of a control method of the carbon dioxide air conditioning system of the present invention. As described above, the refrigerant circulation path may be determined by dividing into the cooling mode / heating mode, but the vehicle air conditioning is further refined by allowing more automatic control as shown in FIGS. 6A and 6B using various conditions such as the outside temperature. Can be adjusted.

Although not shown first, the cooling mode control method of the present invention will be described. In the carbon dioxide air conditioning system of the present invention, first, when a1) a cooling mode is selected by a user, a2) converts a flow path so that the first bypass valve 710 distributes the refrigerant to the first gas cooler 110. In addition, the second bypass valve 720 switches the flow path so as to distribute the refrigerant from the internal heat exchanger 200. Of course, if this state is the default state, the switching operation may not actually be performed. Next, a3) the air opening and closing door 910 is arranged such that the air passing only the evaporator 500 is introduced into the vehicle. In this case, air cooled by the evaporator 500 flows into the vehicle, thereby cooling the vehicle.

Next, the dehumidification mode control method shown in FIG. 6A will be described. In FIG. 5B, only the dehumidification is performed. However, as shown in FIG. 6A, more detailed control may be performed in consideration of the outside temperature. In the carbon dioxide air conditioning system of the present invention, first, when b1) a dehumidification mode is selected, the outside air temperature is compared with the preset outside air reference temperature (K _a ) and the outside air temperature (T _ambient ) b2) the outside air temperature than the preset outside air reference temperature (K _a ). When (T _ambient ) is low (K _a <T _ambient : No) (that is, in cold weather) is set to the dehumidification heating mode, the first bypass valve 710 is the refrigerant to the auxiliary heat exchanger (810) side. The flow path is switched so as to flow, and the flow path is switched so that the second bypass valve 720 distributes the refrigerant from the auxiliary heat exchanger 810. In this case, dehumidification is achieved by evaporating moisture in the air by heating. Alternatively, when the outside temperature T _ambient is higher than the preset outside air reference temperature K _a (K _a <T _ambient : Yes) (that is, in hot weather), the first bypass valve is set to a dehumidification cooling mode. 710 converts the flow path so as to distribute the refrigerant to the first gas cooler 110, and converts the flow path so that the second bypass valve 720 distributes the refrigerant from the internal heat exchanger 200. .

At this time, b3) when the dehumidification cooling mode is set in the step b2), when the preset reference temperature T _setting is lower than the vehicle indoor temperature T _int (T _int <T _setting : No) When hot) The air opening and closing door 910 is arranged such that the air passing only the evaporator 500 is introduced into the vehicle interior, thereby cooling the inside of the vehicle. As the air is cooled in the evaporator 500, dehumidification is performed, and when cooling is performed, dehumidification is automatically performed together. Substantially, it operates in the same manner as the cooling mode illustrated in FIG. 5A. Alternatively, when the preset reference temperature T _setting is higher than the vehicle indoor temperature T _int (T _int <T _setting : Yes) (that is, when the inside of the vehicle is not hot), the ventilation opening and closing door 910 is the evaporator 500. ) And the air passing through the second gas cooler 120 sequentially enters the vehicle interior, so that only dehumidification is performed inside the vehicle. This case is substantially the form shown in Fig. 5B.

Next, the heating mode control method shown in FIG. 6B is demonstrated. When the first user by c1) heating mode is selected, the comparison is based on the outside air temperature (K _a) and the outside air temperature (T _ambient) set in advance. At this time, c2) when the ambient temperature (T _ambient ) is higher than the preset outside air reference temperature (K _a ) (K _a <T _ambient : Yes) (that is, when the weather is not very cold) is set to the normal heating mode, The first bypass valve 710 to switch the flow path to distribute the refrigerant to the auxiliary heat exchanger 810 side, and the second bypass valve 720 to distribute the refrigerant from the auxiliary heat exchanger 810 The flow path is switched and the air flow to the first gas cooler 110 and the auxiliary heat exchanger 810 is opened. That is, the heating mode refrigerant circulation path as shown in FIGS. 5C and 5 is achieved.

Alternatively, when the ambient temperature (T _ambient ) is lower than the preset outside reference temperature (K _a ) (K _a <T _ambient : No) (that is, when the weather is considerably cold), the low temperature heating mode is set, and the preset refrigerant reference temperature is set. (K _c ) and the refrigerant temperature (T _coolant ) will be compared. At this time, c3) when the low temperature heating mode is set in step c2), when the coolant temperature T _coolant is higher than the preset coolant reference temperature K _c (K _c <T _coolant : Yes) (that is, the coolant temperature is very high). When it is not low) the first bypass valve 710 switches the flow path to distribute the refrigerant to the auxiliary heat exchanger 810 side, the second bypass valve 720 from the auxiliary heat exchanger 810 The flow path is switched to distribute the refrigerant, and the air flow to the first gas cooler 110 and the auxiliary heat exchanger 810 is closed. Alternatively, when the coolant temperature T _coolant is lower than the preset coolant reference temperature K _c (K _c <T _coolant : No) (that is, when the weather is very cold and the coolant temperature is too low), the cryogenic heating mode is set. The first bypass valve 710 switches the flow path so as to distribute the refrigerant to the auxiliary heat exchanger 810, and the second bypass valve 720 distributes the refrigerant from the auxiliary heat exchanger 810. To switch the flow path, the air flow to the first gas cooler 110 and the auxiliary heat exchanger 810 is closed, and the auxiliary heat source 800 is operated to supply heat to the auxiliary heat exchanger 810. do. In FIG. 6B, the auxiliary heat source 800 is formed of an electric heater, that is, the auxiliary heat source 800 is operated in a cryogenic state to quickly heat the refrigerant.

Next, c4) when the cryogenic heating mode is set in step c3), when the compressor inlet refrigerant temperature T _{ref_suc} is lower than the preset compressor inlet refrigerant reference temperature K _s (K _s <T _{ref_suc} : No) When the auxiliary heat source 800 is repeatedly operated to raise the temperature of the refrigerant to a sufficient state, and the compressor inlet refrigerant temperature T _{ref_suc} is higher than the preset compressor inlet refrigerant reference temperature K _s (K _s <T _{ref_suc} : Yes) It _{goes to the} next step. Since the refrigerant in the cryogenic state is very high in viscosity and the refrigerant fluidity is poor, when the refrigerant in such a state flows into the compressor 400 as it is, the problem of slugging and overheating in the compressor 400 increases. do. However, by improving the refrigerant flowability by sufficiently warming the refrigerant by using the auxiliary heat source 800, c5) by allowing the compressor 400 to start operation, the present invention can solve the problems described above.

After the heating mode is applied in this manner, c6) the air opening and closing door 910 is arranged such that air passing through the evaporator 500 and the second gas cooler 120 sequentially enters the vehicle interior, thereby providing heat to the surroundings. The heated air is introduced into the vehicle by passing through the discharged second gas cooler 120. In this case, since the evaporator 500 does not operate, only the heating of the air is performed, thereby allowing the inside of the vehicle to be heated smoothly.

The present invention is not limited to the above-described embodiments, and the scope of application of the present invention is not limited to those of ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications can be made.

1 is a carbon dioxide air conditioning system according to the prior art.

2a, 2b and 2c is a refrigerant circulation path in the carbon dioxide air conditioning system according to the prior art.

Figure 3 is a graph of the characteristic change of the refrigerant and air with time in the carbon dioxide air conditioning system according to the prior art.

4 is a carbon dioxide air conditioning system according to the present invention.

5a, 5b, 5c and 5d is a refrigerant circulation path in the carbon dioxide air conditioning system according to the present invention.

6a and 6b is a carbon dioxide air conditioning system control method according to the present invention.

DESCRIPTION OF REFERENCE NUMERALS

1110: conventional gas cooler 1120: conventional gas cooler

1200: (conventional) internal heat exchanger

1210: (traditional heat exchanger) the first euro

1220: (Conventional Heat Exchanger) Second Euro

1300: (conventional) accumulator

1400: (conventional) compressor 1500: (conventional) evaporator

1611: (conventional) first expansion valve 1621: (conventional) second expansion valve

1612: (traditional) first bypass valve 1622: (conventional) second bypass valve

110: first gas cooler 120: second gas cooler

200: internal heat exchanger

210: first euro 220: second euro

300: accumulator

400: compressor 500: evaporator

610: first expansion valve 620: second expansion valve

710: first bypass valve 720: second bypass valve

800: auxiliary heat source 810: auxiliary heat exchanger

900: air distribution path 910: ventilation opening and closing door

Claims (9)

A compressor 400 for compressing the refrigerant; An evaporator 500 for evaporating the refrigerant passing through the first expansion valve 610 in the cooling mode; A first gas cooler 110 and a second gas cooler 120 configured to selectively heat the refrigerant introduced therein according to the mode to exchange heat with air; An auxiliary heat exchanger 810 disposed in parallel with the first gas cooler 110 to evaporate the refrigerant passing through the second expansion valve 620 in a heating mode; An auxiliary heat source 800 for supplying heat to the auxiliary heat exchanger 810; The first flow path 210 and the second flow path 220 in which the low temperature / low pressure refrigerant discharged from the evaporator 500 and the high temperature / high pressure refrigerant discharged from the first gas cooler 110 are closely connected to each other in the cooling mode. Internal heat exchanger 200 for mutual heat exchange by circulating through each; A first bypass valve 710 and a second bypass valve 720 for switching a circulation path of the refrigerant in the cooling mode and the heating mode; And, The first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to one selected from the first gas cooler 110 and the auxiliary heat exchanger 810. The pass valve 720 distributes the refrigerant flowing from one selected from the internal heat exchanger 200 and the auxiliary heat exchanger 810 to the compressor 400, The refrigerant is circulated through any one path selected from a cooling mode refrigerant circulation path and a heating mode refrigerant circulation path formed by the selection of an open flow path of the first bypass valve 710 and the second bypass valve 720. Carbon dioxide air conditioning system, characterized in that. The method of claim 1, wherein the cooling mode refrigerant circulation path, The first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to the first gas cooler 110, and the second bypass valve 720 supplies the internal heat exchanger 200. By flowing the refrigerant flowing from the side to the compressor 400, The refrigerant flowing from the compressor 400 passes through the second gas cooler 120, passes through the first gas cooler 110 through the first bypass valve 710, and passes through the internal heat exchanger 200. And expands while passing through the second flow path 220 of the first flow valve 610, and then evaporates while passing through the evaporator 500 to cool air, and the first flow path of the internal heat exchanger 200. (210) and the second bypass valve 720, the carbon dioxide air conditioning system, characterized in that flowing into the compressor (400). The method of claim 1, wherein the heating mode refrigerant circulation path, The first bypass valve 710 distributes the refrigerant flowing from the second gas cooler 120 to the auxiliary heat exchanger 810, and the second bypass valve 720 supplies the auxiliary heat exchanger 810. By flowing the refrigerant flowing from the side to the compressor 400, The refrigerant flowing from the compressor 400 heats air while passing through the second gas cooler 120 and expands while passing through the second expansion valve 620 through the first bypass valve 710. After that, the evaporation while passing through the auxiliary heat exchanger (810), and passes through the second bypass valve (720), the carbon dioxide air conditioning system, characterized in that flowing into the compressor (400). The method of claim 1, wherein the auxiliary heat source 800 is Carbon dioxide air conditioning system, characterized in that formed of at least one selected from the electric heater, a warmer using a cooling water, a heat pump heat exchanger using a refrigerant. The method according to any one of claims 1 to 4, wherein the evaporator 500 and the second gas cooler 120 is Is provided in the air flow path (900) flowing into the vehicle, the second gas cooler (120) is a carbon dioxide air conditioning system, characterized in that provided in the downstream of the evaporator (500). The method of claim 5, wherein the air flow path (900) To change the air flow so that the air passing through only the evaporator 500 is introduced into the vehicle or the air passing through the evaporator 500 and the second gas cooler 120 sequentially enters the vehicle. Carbon dioxide air conditioning system comprising a ventilation opening and closing door (910). In the carbon dioxide air conditioning system control method using the carbon dioxide air conditioning system according to claim 6, a1) selecting a cooling mode; a2) the first bypass valve 710 switches the flow path so as to distribute the refrigerant to the first gas cooler 110, and the second bypass valve 720 receives the refrigerant from the internal heat exchanger 200; Converting the flow path for circulation; a3) arranging the air opening and closing door 910 such that air passing only the evaporator 500 flows into the vehicle; Carbon dioxide air conditioning system control method comprising a. In the carbon dioxide air conditioning system control method using the carbon dioxide air conditioning system according to claim 6, b1) selecting a dehumidification mode; b2) When the outside temperature T _ambient is lower than the preset outside air reference temperature K _a (K _a <T _ambient : No), a dehumidification heating mode is set, and the first bypass valve 710 is configured to exchange the auxiliary heat. The flow path is switched to circulate the refrigerant to the air 810 side, and the second bypass valve 720 is switched to flow the refrigerant from the auxiliary heat exchanger 810, When the _ambient air temperature T _ambient is higher than _a preset outside air reference temperature K _a (K _a <T _ambient : Yes), a dehumidification cooling mode is set, and the first bypass valve 710 is set to the first gas cooler. Switching the flow path to circulate the refrigerant to the side (110), and switching the flow path so that the second bypass valve 720 circulates the refrigerant from the internal heat exchanger (200); b3) If the dehumidification cooling mode is set in the step b2), When the preset reference temperature T _setting is lower than the vehicle interior temperature T _int (T _int <T _setting : No), air passing through only the evaporator 500 is introduced into the vehicle. Deployed, When the preset reference temperature T _setting is higher than the vehicle interior temperature T _int (T _int <T _setting : Yes), the ventilation opening and closing door 910 opens the evaporator 500 and the second gas cooler 120. Arranging the air passing through the air to be sequentially introduced into the vehicle; Carbon dioxide air conditioning system control method comprising a. In the carbon dioxide air conditioning system control method using the carbon dioxide air conditioning system according to claim 6, c1) a heating mode is selected; c2) When the _ambient air temperature T _ambient is higher than _a preset outside air reference temperature K _a (K _a <T _ambient : Yes), the first bypass valve 710 is set to a general heating mode, so that the first heat exchange The flow path is switched to circulate the refrigerant to the air 810, the second bypass valve 720 switches the flow path to circulate the refrigerant from the auxiliary heat exchanger 810, and the first gas cooler 110. ) And the air circulation to the auxiliary heat exchanger 810 is opened, When the _ambient air temperature (T _ambient ) is lower than the preset outside air reference temperature (K _a ) (K _a <T _ambient : No) It is set to the low temperature heating mode, and the preset refrigerant reference temperature (K _c ) and the refrigerant temperature (T comparing _coolant ); c3) if the low temperature heating mode is set in step c2), When the coolant temperature T _coolant is higher than the preset coolant reference temperature K _c (K _c <T _coolant : Yes), the first bypass valve 710 distributes the coolant to the auxiliary heat exchanger 810. To switch the flow path so that the second bypass valve 720 distributes the refrigerant from the auxiliary heat exchanger 810, and the first gas cooler 110 and the auxiliary heat exchanger 810. Air distribution to the furnace is closed, When the coolant temperature T _coolant is lower than the preset coolant reference temperature K _c (K _c <T _coolant : No), the cryogenic heating mode is set, so that the first bypass valve 710 is connected to the auxiliary heat exchanger. The flow path is switched to distribute the refrigerant to the side 810, the second bypass valve 720 switches the flow path to distribute the refrigerant from the auxiliary heat exchanger 810, and the first gas cooler 110 and Closing the air flow to the auxiliary heat exchanger (810), and operating the auxiliary heat source (800) to supply heat to the auxiliary heat exchanger (810); c4) if the cryogenic heating mode is set in step c3), When the compressor inlet refrigerant temperature T _{ref_suc} is lower than the preset compressor inlet refrigerant reference temperature K _s (K _s <T _{ref_suc} : No), the operation of the auxiliary heat source 800 is repeated. When the compressor inlet refrigerant temperature T _{ref_suc} is higher than the preset compressor inlet refrigerant reference temperature K _s (K _s <T _{ref_suc} : Yes), the process proceeds to the next step; c5) the compressor 400 starts to operate; c6) arranging the air opening and closing door 910 such that air sequentially passing through the evaporator 500 and the second gas cooler 120 flows into the vehicle; Carbon dioxide air conditioning system control method comprising a.

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