Air conditioner

Abstract

This air conditioner comprises an outdoor heat exchanger (5). The outdoor heat exchanger (5) comprises a fan (6), and a plurality of refrigerant flow passages (12) in which a refrigerant flows and which receive wind generated by the fan (6) and perform heat exchange between the refrigerant and air. During a heating operation, among the plurality of refrigerant flow passages (12), a smaller amount of refrigerant is configured to flow in those that receive less of the wind than in those that receive the wind well, and thus the refrigerant in the former enters an overheated state more quickly.

Description

Air conditioner

[0001] The present invention relates to an air conditioner.

[0002] As the background art of this technical field, there is Japanese Patent No. 6278904 (Patent Document 1). This publication states that "in a heat pump device such as an air conditioner or a refrigeration device, in a heat exchanger that acts as a condenser or an evaporator, when the refrigerant flow path has a plurality of passes, a refrigerant distributor for distributing the refrigerant to each pass is required on the refrigerant inlet side." (See the claims).

[0003] Japanese Patent No. 6278904

[0004] [[ID=??]] However, the technology disclosed in Patent Document 1 had room for improvement from the viewpoint of increasing the heating efficiency during the heating operation of the air conditioner. Therefore, an object of the present invention is to provide an air conditioner capable of increasing the heating efficiency during the heating operation of the air conditioner.

[0005] To solve the above problems, the present invention includes an outdoor heat exchanger having a plurality of refrigerant flow paths, a fan that sends wind to the outdoor heat exchanger, and a refrigerant distributor that distributes refrigerant to the plurality of refrigerant flow paths. The fan is disposed at a position where the wind speed at the upper end of the outdoor heat exchanger is smaller than that at the center of the outdoor heat exchanger. The refrigerant distributor distributes the refrigerant so that the average value of the outlet temperature or dryness of the refrigerant flow path located at the uppermost side of the outdoor heat exchanger is higher than that of the refrigerant flow path located at the center of the outdoor heat exchanger during a predetermined period.

[0006] According to the present invention, it is possible to increase the heating efficiency during the heating operation of the air conditioner and the like. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

[0007] It is a schematic configuration diagram of the air conditioner of this embodiment. It is a conceptual diagram of the outdoor heat exchanger according to this embodiment. It is a conceptual diagram showing an example of the arrangement relationship between the outdoor heat exchanger and the fan according to this embodiment. It is a conceptual diagram of another example different from FIG. 3 showing an example of the arrangement relationship between the outdoor heat exchanger and the fan according to this embodiment. It is a conceptual diagram of an outdoor heat exchanger as a comparative example for this embodiment.

[0008] It should be noted that there seems to be a typo in line 12 where "請求の範囲参照" is not translated. Also, line 21 has some text that might be a bit unclear in its context and translation requirements as it seems to be a list of descriptions about diagrams but not fully clear what the exact translation nuances should be for the repeated "本実施形態かかる". The above translation attempts to make sense of the overall text as best as possible.Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram of the air conditioner of this embodiment. The air conditioner 100 of this embodiment comprises an outdoor unit 1 and an indoor unit 2. The outdoor unit 1 comprises a compressor 3 for compressing the refrigerant, a four-way valve 4 for switching the direction of the refrigerant flow, an outdoor heat exchanger 5 for exchanging heat between the outdoor air and the refrigerant, a fan 6 for taking outdoor air into the outdoor unit 1, and an expansion valve 7 for expanding the refrigerant.

[0009] The indoor unit 2 is equipped with an indoor heat exchanger 8 that exchanges heat between indoor air and refrigerant, and a once-through fan 9 that acts as a blower fan to draw indoor air into the indoor unit 2. In the outdoor unit 1, the compressor 3, four-way valve 4, outdoor heat exchanger 5, expansion valve 7, and indoor heat exchanger 8 are connected by piping 10, allowing the refrigerant to circulate through each component via piping 10. Various refrigerants such as R410A and R32 can be used as the refrigerant. During cooling operation of the air conditioner 100, the four-way valve 4 is connected as shown by the solid line in Figure 1. In this case, the refrigerant discharged from the compressor 3 flows in the order of outdoor heat exchanger 5, expansion valve 7, and indoor heat exchanger 8, and then circulates back to the compressor 3 (see solid arrow in Figure 1). On the other hand, during heating operation of the air conditioner 100, the four-way valve 4 is connected as shown by the dashed line in Figure 1. In this case, the refrigerant discharged from the compressor 3 flows through the indoor heat exchanger 8, the expansion valve 7, and the outdoor heat exchanger 5 in that order, and then circulates back to the compressor 3 (see the dashed arrow in Figure 1).

[0010] Inside the outdoor unit 1, outdoor air is drawn in by the fan 6 and passes through the outdoor heat exchanger 5, where heat exchange takes place between the outdoor air and the refrigerant. Inside the indoor unit 2, indoor air is drawn in by the through-flow fan 9 and passes through the indoor heat exchanger 8, where heat exchange takes place between the indoor air and the refrigerant. The air conditioner 100 then blows out conditioned air, which is indoor air that has been heated or cooled by heat exchange with the refrigerant, to provide air conditioning for the room.

[0011] Here, the background and problems of this embodiment will be explained. Figure 5 is a conceptual diagram of an outdoor heat exchanger that serves as a comparative example to this embodiment. Although it is a comparative example, in the following description, components common to Figure 1 will be described using the same reference numerals as in Figure 1. The outdoor heat exchanger 5 has multiple refrigerant flow paths 12 through which the refrigerant flows in one direction and which receive airflow generated by the fan 6 to perform heat exchange between the refrigerant and the air. These paths are arranged, for example, in multiple directions with the longitudinal direction as the horizontal (only six are shown in the example of Figure 5), or in a vertical direction. Although not shown, the refrigerant flow paths 12 are provided with a number of well-known fins for heat exchange.

[0012] The flow of refrigerant when the air conditioner 100 is in heating operation is as follows. First, the refrigerant from the indoor heat exchanger 8 is liquefied to, for example, about 20°C (we will mention specific temperatures below, but this is merely an example), and it flows through the subcooler 11, passes through the expansion valve 7 and expands, and its temperature drops to, for example, 5 to -10°C. At this time, the refrigerant is generally in a state that is a mixture of liquid and gas.

[0013] The refrigerant is then distributed to each distribution pipe 13 by the distributor 14. Each distribution pipe 13 is connected, for example, in a one-to-one relationship to one end of the refrigerant flow path 12 (the right end in Figure 5). Therefore, the refrigerant distributed to each distribution pipe 13 flows in each refrigerant flow path 12 in one direction, from right to left in the example in Figure 5. The distribution pipes 13 and the distributor 14 together are called the refrigerant distribution means 15. At this time, the refrigerant in each refrigerant flow path 12, for example, at around 0°C, receives air from the fan 6, for example at around 7°C, and undergoes heat exchange with the air, becoming almost entirely gaseous refrigerant within the refrigerant flow path 12. This gaseous refrigerant is collected from each refrigerant flow path 12 in the gas header 15 and flows towards the four-way valve 4.

[0014] In each refrigerant flow path 12, we want the refrigerant to be sufficiently heated by the airflow from the fan 6. In other words, to improve heating efficiency, we want to utilize the entire outdoor heat exchanger 5 as much as possible so that the refrigerant can absorb sufficient heat. However, if we distribute the refrigerant equally to each refrigerant flow path 12 in this case, there will be losses. This is because the airflow generated by the fan 6 does not hit all of the refrigerant flow paths 12 equally. In the example in Figure 5, the fan 6 is positioned so that the airflow velocity at the top of the outdoor heat exchanger 5 is lower than that at the center of the outdoor heat exchanger 5. Therefore, the refrigerant flow paths 12 on the central side of the outdoor heat exchanger 5 are hit well (they receive a lot of airflow), and the refrigerant dries out quickly in these refrigerant flow paths 12. On the other hand, in the upper refrigerant flow paths 12 as in the example in Figure 5, the airflow from the fan 6 does not reach them as well (they receive less airflow), so the refrigerant that has passed through the refrigerant flow paths 12 does not dry completely and remains in a liquid state. In the example in Figure 5, the uppermost refrigerant flow pipe 12 receives the least airflow.

[0015] Therefore, in order to make full use of the indoor heat exchanger 8 (heat transfer area), in the example of Figure 5, it is common to reduce the amount of refrigerant distributed in the upper refrigerant flow path 12, which is less exposed to airflow. Methods for changing the amount of refrigerant flow include changing the length of the distribution pipe 13 (i.e., the piping between the distributor 14 and the heat transfer tubes 12) or changing its inner or outer diameter, depending on each refrigerant flow path 12. As a result, in the outdoor heat exchanger 5, in the example of Figure 5, as the refrigerant flows from right to left, the refrigerant dries out within each refrigerant flow path 12, and the refrigerant superheats in the areas of the outdoor heat exchanger 5 indicated by the darker colored reference numeral 16. Despite the differences in airflow from the fan 6, the refrigerant superheats (is uniformly superheated) at approximately the same position in the left-right direction throughout the entire upper and lower parts of the outdoor heat exchanger 5. This is near the gas header 15, and it can be said that the outdoor heat exchanger 5 is being utilized sufficiently efficiently during heating operation.

[0016] In this system, during heating operation, the outdoor heat exchanger 5 is blown with air at a temperature of approximately 7°C by the fan 6. However, if the refrigerant is at a low temperature, such as -2°C or -3°C, this temperature is below freezing, causing moisture in the air to freeze on the surface of the outdoor heat exchanger 5. As a result, the area of ​​the surface of the fins (not shown as described above) of the outdoor heat exchanger 5 that is not frozen is reduced. Consequently, the fins freeze and become unusable. In other words, it becomes difficult for the air from the fan 6 to reach the fins.

[0017] Therefore, as a countermeasure, the control performed by the air conditioner 100 is generally to cool the refrigerant further to increase the temperature difference between the refrigerant and the air with which it exchanges heat. This is because the increased temperature difference between the refrigerant and the air improves the heating capacity. However, this further lowers the temperature of the refrigerant, causing the surface of the outdoor heat exchanger 5 to freeze even more, leading to a vicious cycle where the control is then performed to cool the refrigerant even further. As a result, frost accumulates on the surface of the outdoor heat exchanger 5.

[0018] As a countermeasure, when a certain amount of frost accumulates on the surface of the outdoor heat exchanger 5, the air conditioner 100 performs a defrosting operation. Unlike the heating operation described above, this operation involves introducing a high-temperature refrigerant from the gas header 15 into the outdoor heat exchanger 5 to melt the frost accumulated on it. However, performing such a defrosting operation means that the heating operation of the air conditioner 100 is stopped during that time. Since the heating operation includes the defrosting operation, if frost accumulates on the outdoor heat exchanger 5 frequently as described above, and defrosting operations become frequent, the overall heating operation of the air conditioner 100, including the defrosting operation, will be less efficient.

[0019] Incidentally, with the recent rise in the market price of copper, aluminum is increasingly being used instead of copper for piping and other materials in air conditioners 100. However, from a material standpoint, using aluminum instead of copper for the outdoor heat exchanger 5 presents a problem: the wall thickness of the aluminum refrigerant flow path 12 and other piping must be increased, otherwise these pipes will not be able to withstand the pressure. In this case, the only solutions that are usually considered are to either increase the outer diameter of the refrigerant flow path 12 and other piping while maintaining the inner diameter, or to maintain the outer diameter and decrease the inner diameter. If the outer diameter is increased, the manufacturing process cannot use the equipment that was used to manufacture existing small-diameter piping. In this case, the manufacturing process will require the installation of new manufacturing equipment, resulting in a significant capital investment. On the other hand, if the inner diameter is decreased while maintaining the outer diameter, the aforementioned capital investment can be suppressed to some extent. However, in this case, a problem arises in which the pressure loss of the refrigerant in the refrigerant flow path 12 and other piping increases. When such an increase in refrigerant pressure loss occurs, the temperature of the refrigerant also decreases. For example, if we compare a copper pipe and an aluminum pipe, both with an outer diameter of 7 mm, the aluminum pipe is more prone to frost buildup. However, even with the copper pipe, reducing the inner diameter leads to the aforementioned pressure loss and other problems. In other words, problems remain with both types of pipes.

[0020] Next, the technical means and effects of this embodiment for solving the above-mentioned problems will be explained. Figure 2 is a conceptual diagram of the outdoor heat exchanger according to this embodiment. The same reference numerals as in Figure 2 refer to the same components as described above, and a detailed explanation will be omitted.

[0021] Figure 2 will be explained focusing on the differences between it and Figure 5. The fan 6 is positioned so that the airflow velocity at the upper end of the outdoor heat exchanger 5 is lower than that at the center of the outdoor heat exchanger 5. The refrigerant distribution means (distribution pipe 13, distributor 14, etc.) distributes the refrigerant so that, over a predetermined period, the average outlet temperature or dryness of the refrigerant flow path 12 located at the uppermost part of the outdoor heat exchanger 5 is higher than that of the refrigerant flow path 12 located at the center of the outdoor heat exchanger 5. A specific means is to make the amount of refrigerant supplied to each refrigerant flow path 12 different from that explained with reference to Figure 5. More specifically, the refrigerant distribution means 15 makes it possible to set the amount of refrigerant flowing to each refrigerant flow path 12 by adjusting the length and diameter of each distribution pipe 13, etc. (piping between the distributor 14 and the heat transfer tube 12), for example.

[0022] In comparison with the example in Figure 5, in the example in Figure 2, the superheating state (part 16) occurs earlier in the lower part 162 of the outdoor heat exchanger 5 (part 161) than in the upper part 161. This is a point in which the present embodiment in Figure 2 differs from the comparative example in Figure 5. For example, in the example in Figure 5, if the refrigerant temperature is -3°C, -4°C, etc., frost will form only on the upper part of the outdoor heat exchanger 5 first. In the lower part of the outdoor heat exchanger 5, exposure to a strong fan 6 at, for example, 7°C makes it easier for frost to melt rather than for it to form. However, even if the refrigerant temperature is the same, for example, -3°C, the airflow from the fan 6 is less in the upper part of the outdoor heat exchanger 5, so it can be said that frost is more likely to form than for it to melt. Therefore, in the example in Figure 2, even if the refrigerant temperature is, for example, -3°C, the wind temperature of 7°C has a greater effect on the upper part of the outdoor heat exchanger 5, making it easier for frost to melt than for it to form. This is the reason why the upper part of the outdoor heat exchanger 5 becomes overheated (superheated) more quickly. In this way, the upper part of the outdoor heat exchanger 5 in Figure 2 is set to vaporize the refrigerant earlier than the lower part.

[0023] However, compared to the example in Figure 5, this means that the capacity of the outdoor heat exchanger 5 is not intentionally fully utilized in this embodiment in Figure 2. However, according to this embodiment, it is possible to make it less likely for frost to form on the entire outdoor heat exchanger 5. As a result, the number of defrosting operations can be reduced. Therefore, in order to improve the overall operating efficiency of the heating capacity, including defrosting operations, this embodiment in Figure 2 is more effective than the comparative example in Figure 5. This is because the number of times the heating operation is stopped due to defrosting operations is reduced. The applicant's verification also confirmed that the overall heating operation efficiency is improved with the configuration of this embodiment in Figure 2 compared to the configuration in Figure 5.

[0024] Furthermore, existing equipment can be utilized to a considerable extent in the manufacturing process for the refrigerant flow path 12, etc. Therefore, new capital investments as described above can be suppressed, and the manufacturing cost of the air conditioner 100 can be reduced. As mentioned above, for example, if copper pipes and aluminum pipes, both with an outer diameter of 7 mm, frost is more likely to accumulate on the aluminum pipes. However, even with copper pipes, reducing the inner diameter causes the aforementioned pressure loss and other problems. Therefore, this embodiment is particularly effective when the piping for the refrigerant flow path 12, etc., is made of aluminum. However, even if these pipes are made of copper, the embodiment is still effective as it can avoid the aforementioned pressure loss and other problems. As a modification of this embodiment, the fan 6 may be positioned so that the wind speed at the lower end of the outdoor heat exchanger 5 is lower than that at the center of the outdoor heat exchanger 5, and during heating operation, the high-pressure refrigerant before passing through the expansion valve 7 may flow through the refrigerant flow path 12 located at the lowest end of the outdoor heat exchanger 5. As another variation, the fan 6 may be positioned such that the airflow velocity at the lower end of the outdoor heat exchanger 5 is lower than that at the center of the outdoor heat exchanger 5, and the refrigerant distributor may be configured such that, over a predetermined period, the average outlet temperature or dryness of the refrigerant flow path located at the lowest part of the outdoor heat exchanger 5 is higher than that of the refrigerant flow path located at the center of the outdoor heat exchanger.

[0025] Figures 3 and 4 are conceptual diagrams showing examples of the arrangement of an outdoor heat exchanger and a fan. Both examples show the arrangement of the outdoor heat exchanger 5 and the fan 6, as well as the strength of the airflow passing through the outdoor heat exchanger 5. In Figures 3 and 4, the strength of the airflow generated by the fan 6 is indicated by a dashed arrow labeled 21. The direction of the airflow generated by the fan 6 is indicated by arrow 22. Furthermore, the direction of the airflow passing through the outdoor heat exchanger 5 is indicated by arrow 23.

[0026] In the example shown in Figure 3, the direction of the airflow generated by the fan 6 and the direction of the air passing through the outdoor heat exchanger 5 are approximately the same. As indicated by the length of the dashed line of arrow 21, the airflow strength is stronger when passing through the central part of the outdoor heat exchanger 5 in the vertical direction, and weaker when passing through the upper and lower ends of the outdoor heat exchanger 5. Therefore, in this case, the amount of refrigerant flowing through the upper and lower ends of the outdoor heat exchanger 5 should be gradually reduced as it approaches the upper and lower ends, compared to the central part in the vertical direction.

[0027] In the example shown in Figure 4, the direction of the airflow generated by the fan 6 and the direction of the air passing through the outdoor heat exchanger 5 are different. In this example, the fan 6 is positioned diagonally above the outdoor heat exchanger 5. Therefore, the airflow is strongest at a position slightly below the upper part of the outdoor heat exchanger 5 in the vertical direction, and weakens as you go lower. Thus, in this case, the amount of refrigerant flowing downwards is gradually reduced compared to the position near the top of the outdoor heat exchanger 5. It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described.

[0028] 5 Outdoor heat exchanger 6 Fan 12 Refrigerant flow path 13 Distribution pipe 14 Distributor 15 Refrigerant distribution means 100 Air conditioner

Claims

1. An air conditioner comprising: an outdoor heat exchanger having a plurality of refrigerant passages; a fan that blows air onto the outdoor heat exchanger; and a refrigerant distribution means for distributing refrigerant to the plurality of refrigerant passages, wherein the fan is positioned such that the air velocity at the upper end of the outdoor heat exchanger is less than that at the center of the outdoor heat exchanger; and the refrigerant distribution means distributes refrigerant such that, over a predetermined period, the average outlet temperature or dryness of the refrigerant passage located at the uppermost part of the outdoor heat exchanger is higher than that of the refrigerant passage located at the center of the outdoor heat exchanger.

2. The air conditioner according to claim 1, wherein the fan is positioned such that the airflow velocity at the lower end of the outdoor heat exchanger is less than that at the center of the outdoor heat exchanger, and during heating operation, high-pressure refrigerant flows through the refrigerant flow path located at the lowest end of the outdoor heat exchanger before passing through the expansion valve.

3. The air conditioner according to claim 1, wherein the fan is positioned such that the air velocity at the lower end of the outdoor heat exchanger is less than that at the center of the outdoor heat exchanger, and the refrigerant distribution means distributes the refrigerant such that, over a predetermined period of time, the average value of the outlet temperature or dryness of the refrigerant flow path located at the lowest part of the outdoor heat exchanger is higher than that of the refrigerant flow path located at the center of the outdoor heat exchanger.

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