Air conditioners

Abstract

This air conditioner is equipped with an outdoor heat exchanger (5). The outdoor heat exchanger 5 is equipped with a fan 6 and a plurality of refrigerant flow paths (12) through which a refrigerant flows and which exchanges heat between the refrigerant and air by receiving the wind generated by the fan (6). During heating operation, the amount of refrigerant flowing through those of the plurality of refrigerant flow paths (12) that receive less wind is set to be smaller than that of those that receive a lot of wind, so that the refrigerant therein becomes overheated more quickly in the latter.

Description

[Technical field]

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

[0002] Background art of this technical field is Japanese Patent No. 6278904 (Patent Document 1), which states that "in a heat exchanger that acts as a condenser or evaporator in a heat pump device such as an air conditioner or a refrigeration device, when the refrigerant flow path has multiple paths, a refrigerant distributor that distributes the refrigerant to each path is required on the refrigerant inlet side" (see claims). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6278904 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology disclosed in Patent Document 1 leaves room for improvement in terms of increasing the heating efficiency during heating operation of the air conditioner. Therefore, an object of the present invention is to provide an air conditioner that can improve the heating efficiency during heating operation of the air conditioner. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides an air conditioner comprising an outdoor heat exchanger having a plurality of refrigerant flow paths, a fan that blows air into the outdoor heat exchanger, and a refrigerant distributor that distributes refrigerant to the plurality of refrigerant flow paths, wherein the fan is positioned at a position where the wind speed at the top end of the outdoor heat exchanger is slower than at the center of the outdoor heat exchanger, and the refrigerant distributor distributes refrigerant so that, over a specified period of time, the average outlet temperature or dryness fraction of the refrigerant flow path located at the top of the outdoor heat exchanger is higher than that of the refrigerant flow path located at the very center of the outdoor heat exchanger. Effect of the Invention

[0006] According to the present invention, it is possible to improve the heating efficiency during heating operation of an air conditioner. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention. [Diagram 2] 1 is a conceptual diagram of an outdoor heat exchanger according to an embodiment of the present invention. [Diagram 3] 4 is a conceptual diagram showing an example of the arrangement relationship between the outdoor heat exchanger and the fan according to the embodiment. FIG. [Figure 4] 4 is a conceptual diagram showing an example of the arrangement relationship between the outdoor heat exchanger and the fan according to the present embodiment, different from that shown in FIG. 3. FIG. [Diagram 5] FIG. 4 is a conceptual diagram of an outdoor heat exchanger serving as a comparative example to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic diagram of an air conditioner 100 according to the present embodiment. The air conditioner 100 according to the present embodiment includes an outdoor unit 1 and an indoor unit 2. The outdoor unit 1 is equipped with a compressor 3 that compresses the refrigerant, a four-way valve 4 that switches the direction of the refrigerant flow, an outdoor heat exchanger 5 that exchanges heat between the outdoor air and the refrigerant, a fan 6 that takes in the outdoor air into the outdoor unit 1, and an expansion valve 7 that expands the refrigerant.

[0009] The indoor unit 2 is equipped with an indoor heat exchanger 8 that exchanges heat between indoor air and a refrigerant, and a cross-flow fan 9 that serves as a blower fan that takes indoor air into the indoor unit 2. In the outdoor unit 1, the compressor 3, the four-way valve 4, the outdoor heat exchanger 5, the expansion valve 7, and the indoor heat exchanger 8 are connected by piping 10, and the refrigerant can circulate through each device via the piping 10. As the refrigerant, various refrigerants such as R410A and R32 can be used. During cooling operation of the air conditioner 100, the four-way valve 4 is connected as shown by the solid lines in Fig. 1. In this case, the refrigerant discharged from the compressor 3 flows through the outdoor heat exchanger 5, the expansion valve 7, and the indoor heat exchanger 8, in that order, before circulating to the compressor 3 again (see the solid arrows in Fig. 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 lines in Fig. 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, before circulating to the compressor 3 again (see the dashed arrows in Fig. 1).

[0010] Inside the outdoor unit 1, outdoor air is drawn in by a fan 6 and passes through an outdoor heat exchanger 5, thereby exchanging heat between the outdoor air and the refrigerant. Inside the indoor unit 2, indoor air is drawn in by a cross-flow fan 9 and passes through an indoor heat exchanger 8, thereby exchanging heat between the indoor air and the refrigerant. The air conditioner 100 conditions the room by blowing out conditioned air, which is indoor air that has been heated or cooled by exchanging heat with the refrigerant.

[0011] Here, the background and problems of this embodiment will be described. 5 is a conceptual diagram of an outdoor heat exchanger as a comparative example of the present embodiment. Although it is a comparative example, in the following description, the same reference numerals as in FIG. 1 are used to designate the same members as in FIG. In the outdoor heat exchanger 5, a refrigerant flows in one direction inside, and a plurality of refrigerant flow paths 12 (only six are illustrated in the example of FIG. 5 ) that exchange heat between the refrigerant and air are arranged, for example, vertically with the longitudinal direction being the horizontal 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 the refrigerant when the air conditioner 100 is in heating operation is as follows. First, the refrigerant from the indoor heat exchanger 8 is liquefied and is at about 20°C, for example (specific temperature will be mentioned below, but this is merely an example), and flows through the subcooler 11 and expands as it passes through the expansion valve 7, decreasing the temperature to, for example, about 5 to -10°C. At this time, the refrigerant is generally in a state where it is a mixture of liquid and gas.

[0013] This refrigerant is then distributed to each distribution pipe 13 by the distributor 14. Each distribution pipe 13 is connected to one end side (the right end in FIG. 5) of the refrigerant flow passage 12 in a one-to-one relationship, for example. Therefore, the refrigerant distributed to each distribution pipe 13 flows in one direction from right to left in each refrigerant flow passage 12 in the example of FIG. 5. The distribution pipe 13 and distributor 14 are collectively referred to as refrigerant distribution means 15. At this time, the refrigerant at, for example, about 0° C. in each refrigerant flow passage 12 exchanges heat with the air by receiving a wind of, for example, about 7° C. from the fan 6, and is almost entirely turned into gas refrigerant in the refrigerant flow passage 12. This gas refrigerant is collected from each refrigerant flow passage 12 in the gas header 15 and flows to the four-way valve 4 side.

[0014] In each refrigerant flow path 12, it is desired that the refrigerant be sufficiently heated by the wind from the fan 6. In other words, in order to improve the heating efficiency, it is desired to fully utilize the entire outdoor heat exchanger 5 as much as possible so that the refrigerant can absorb sufficient heat. However, in this case, if the refrigerant is distributed equally to each refrigerant flow passage 12, loss occurs. This is because the wind generated by the fan 6 does not hit all the refrigerant flow passages 12 evenly. In the example of FIG. 5, the fan 6 is disposed at a position where the wind speed at the top end of the outdoor heat exchanger 5 is slower than that at the center of the outdoor heat exchanger 5. Therefore, the refrigerant is often hit by the refrigerant flow passages 12 at the center of the outdoor heat exchanger 5 (because they receive a lot of wind), so the refrigerant dries out quickly in these refrigerant flow passages 12. On the other hand, the refrigerant flow passages 12 at the upper side as in the example of FIG. 5 are less hit by the wind of the fan 6 (because they receive less wind), so the refrigerant that has passed through the refrigerant flow passages 12 does not dry completely and remains in a liquid state. In the example of FIG. 5, the refrigerant flow pipe 12 at the top is least hit by the wind.

[0015] Therefore, in order to fully utilize the indoor heat exchanger 8 (heat transfer area), in the example of Fig. 5, it is common to reduce the amount of refrigerant distributed in the upper refrigerant flow passages 12 that are less exposed to wind. The amount of refrigerant flowing is changed by changing the length of the distribution pipes 13 (i.e., the pipes between the distributor 14 and the heat transfer pipes 12) or by changing the thickness of the inner diameter or outer diameter thereof according to each refrigerant flow passage 12. As a result, in the outdoor heat exchanger 5, in the example of Fig. 5, as the refrigerant flows from right to left, the refrigerant dries in each refrigerant flow path 12, and the refrigerant is superheated in the parts of the outdoor heat exchanger 5 indicated by the darker colored reference numeral 16. Despite differences in the degree to which the air from the fan 6 hits the refrigerant, the refrigerant is superheated (evenly overheated) at approximately the same positions in the left-right direction over 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 used sufficiently efficiently during heating operation.

[0016] Here, in heating operation, the fan 6 blows wind at a temperature of, for example, about 7°C onto the outdoor heat exchanger 5. However, if the refrigerant is at a low temperature, such as -2°C or -3°C, this temperature is below freezing, and the moisture in the air freezes on the surface of the outdoor heat exchanger 5. This reduces the area of ​​the unfrozen parts of the surfaces of the fins (not shown, as mentioned above) of the outdoor heat exchanger 5. The fins then freeze, making them difficult to use. In other words, it becomes difficult for the wind from the fan 6 to reach the fins.

[0017] Therefore, as a countermeasure, the air conditioner 100 generally performs control such that the refrigerant is cooled more and the temperature difference between the refrigerant and the air with which it exchanges heat is increased. This is because the temperature difference between the refrigerant and the air increases, improving the heating capacity. However, this further reduces the temperature of the refrigerant, causing the surface of the outdoor heat exchanger 5 to freeze even more, resulting in a vicious cycle in which control is performed to further cool the refrigerant. As a result, frost continues to form on the surface of the outdoor heat exchanger 5.

[0018] As a countermeasure to this, the air conditioner 100 performs a defrosting operation when a certain amount of frost has formed on the surface of the outdoor heat exchanger 5. This operation differs from the heating operation described above, in that a high-temperature refrigerant is introduced into the outdoor heat exchanger 5 from the gas header 15 side in order to melt the frost that has formed on the outdoor heat exchanger 5. 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 frequently forms on the outdoor heat exchanger 5 as described above and the defrosting operation is performed more frequently, the heating operation performance of the air conditioner 100 will decrease when considering the heating operation as a whole, including the defrosting operation.

[0019] Incidentally, with the recent rise in the market price of copper, aluminum has come to be used instead of copper as a material for the piping of the air conditioner 100. However, in terms of material, in order to use aluminum instead of copper for the outdoor heat exchanger 5, the thickness of the piping itself, such as the aluminum refrigerant flow path 12, must be increased, otherwise these piping cannot withstand pressure. In this case, the only possible countermeasures are to enlarge the outer diameter of the piping of the refrigerant flow path 12 and the like and maintain the inner diameter, or to maintain the outer diameter and reduce the inner diameter. In this case, if the outer diameter is to be enlarged, the equipment used for manufacturing the existing piping of a small outer diameter cannot be used in the manufacturing process. In this case, since the new installation of new manufacturing equipment is required in the manufacturing process, a large capital investment is required. On the other hand, if the inner diameter is reduced while maintaining the outer diameter, the capital investment can be suppressed to a certain extent. However, in this case, the pressure loss of the refrigerant in the piping of the refrigerant flow path 12 and the like increases. If such an increase in the pressure loss of the refrigerant occurs, the temperature of the refrigerant also decreases. For example, if we compare a copper pipe and an aluminum pipe, both of which have an outer diameter of 7 mm, we find that the aluminum pipe is more susceptible to frost. However, even in the case of a copper pipe, reducing the inner diameter will cause problems such as the pressure loss mentioned above. In other words, both pipes have problems.

[0020] Next, the technical means and effects of the present embodiment for solving the above problems will be described. Fig. 2 is a conceptual diagram of the outdoor heat exchanger according to this embodiment. The same reference numerals as in Fig. 2 denote the same members as those described above, and detailed description thereof will be omitted.

[0021] The differences between FIG. 2 and FIG. 5 will be mainly described. The fan 6 is disposed at a position where the wind speed at the upper end of the outdoor heat exchanger 5 is smaller than that at the center of the outdoor heat exchanger 5. The refrigerant distribution means (distribution pipe 13, distributor 14, etc.) that distributes the refrigerant distributes the refrigerant so that the average value of the outlet temperature or dryness of the refrigerant flow path 12 located at the uppermost side of the outdoor heat exchanger 5 is higher than that of the refrigerant flow path 12 located at the most center of the outdoor heat exchanger 5 during a predetermined period. A specific means is to make the amount of refrigerant supplied to each refrigerant flow path 12 different from that described with reference to FIG. 5. More specifically, the refrigerant distribution means 15 can set the amount of refrigerant flowing through each refrigerant flow path 12 by, for example, adjusting the length or diameter size of each distribution pipe 13, etc. (pipes between the distributor 14 and the heat transfer tube 12).

[0022] Compared with the example in Fig. 5, in the example in Fig. 2, the part 162 below the part 161 of the outdoor heat exchanger 5 reaches an overheated state earlier than the part 161 (part 16). This is what makes the present embodiment in Fig. 2 different from the comparative example in Fig. 5. For example, in the example of FIG. 5, if the temperature of the refrigerant is -3°C or -4°C, frost will form first only in the upper outdoor heat exchanger 5. In the lower outdoor heat exchanger 5, the frost will melt more easily than it will form when exposed to a strong wind from the fan 6 at, for example, 7°C. However, even if the refrigerant temperature is the same as, for example, -3°C, the upper outdoor heat exchanger 5 has a smaller air volume from the fan 6, so it can be said that frost will form more easily than it will melt. Therefore, in the example of FIG. 2, the upper outdoor heat exchanger 5 has a large effect because the wind is 7°C even if the refrigerant is, for example, -3°C, so it will melt more easily than it will form frost. This is the reason why only the upper outdoor heat exchanger 5 becomes overheated (superheated) earlier. In this way, the upper part of the outdoor heat exchanger 5 in FIG. 2 is set to evaporate the refrigerant earlier than the lower part.

[0023] However, this also means that the capacity of the outdoor heat exchanger 5 is not fully utilized intentionally in the example of the present embodiment in FIG. 2 compared to the example of FIG. 5. However, according to the present embodiment, it is possible to make the outdoor heat exchanger 5 less susceptible to frost formation as a whole. Therefore, the number of defrosting operations described above can be reduced. Therefore, it can be said that the present embodiment in FIG. 2 is more effective than the comparative example in FIG. 5 in improving the overall operating efficiency of the heating capacity including the defrosting operation. This is because the number of times that the original heating operation is stopped due to the defrosting operation is reduced. The applicant's verification also confirmed that the overall efficiency of the heating operation is improved in the configuration of the present embodiment in FIG. 2 compared to the configuration in FIG. 5.

[0024] Furthermore, existing facilities can be used to a large extent in the manufacturing process for the refrigerant flow paths 12, etc. Therefore, the need for new capital investment as described above can be suppressed, and the manufacturing cost of the air conditioner 100 can be reduced. As described above, for example, if a copper tube and an aluminum tube, both of which have an outer diameter of 7 mm, are compared, frost is more likely to form on the aluminum tube. However, even in the case of a copper tube, problems such as the above-mentioned pressure loss occur when the inner diameter is reduced. Therefore, this embodiment is particularly effective when the pipes of the refrigerant flow path 12 and the like are made of aluminum. However, even if these pipes are made of copper, it is still effective because the above-mentioned problems such as pressure loss can be avoided. As a modification of this embodiment, the fan 6 may be positioned at a position where the wind speed at the lower end of the outdoor heat exchanger 5 is slower than at the center of the outdoor heat exchanger 5, and during heating operation, high-pressure refrigerant before passing through the expansion valve 7 may flow through the refrigerant passage 12 located at the lowest end of the outdoor heat exchanger 5. As another modified example, the fan 6 may be arranged at a position where the wind speed at the lower end of the outdoor heat exchanger 5 is slower than at the center of the outdoor heat exchanger 5, and the refrigerant distributor may be configured so that, over a specified 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 5 is higher than that of the refrigerant flow path located at the most center of the outdoor heat exchanger.

[0025] 3 and 4 are both conceptual diagrams showing examples of the positional relationship between the outdoor heat exchanger and the fan. In both examples, the positional relationship between the outdoor heat exchanger 5 and the fan 6, and the strength of the wind passing through the outdoor heat exchanger 5 are shown. In Figs. 3 and 4, the strength of the wind generated by the fan 6 is indicated by a dashed arrow with reference number 21. The direction of the wind generated by the fan 6 is indicated by arrow 22. Furthermore, the direction of the wind passing through the outdoor heat exchanger 5 is indicated by arrow 23.

[0026] 3, the direction of the wind generated by the fan 6 is substantially the same as the direction of the air passing through the outdoor heat exchanger 5. As indicated by the dashed line length of the arrow 21, the strength of the wind passing through the vertical center side of the outdoor heat exchanger 5 is strong, and the strength of the wind passing through the vertical end sides of the outdoor heat exchanger 5 is weak. Therefore, in this case, the amount of refrigerant flowing through the upper and lower end sides compared to the vertical center side of the outdoor heat exchanger 5 is gradually reduced closer to the upper and lower ends.

[0027] In the example of Fig. 4, the direction of the wind generated by the fan 6 is different from the direction of the air passing through the outdoor heat exchanger 5. In this example, the fan 6 is disposed diagonally above the outdoor heat exchanger 5. Therefore, the wind is strongest at a position slightly below the top in the vertical direction of the outdoor heat exchanger 5, and becomes weaker the further down. Therefore, in this case, the amount of refrigerant flowing below the outdoor heat exchanger 5 is gradually reduced compared to a position near the top of the outdoor heat exchanger 5. The present invention is not limited to the above-described embodiment, but includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to the embodiment having all of the described configurations. [Explanation of symbols]

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

Claims

1. an outdoor heat exchanger having a plurality of refrigerant flow paths; A fan for blowing air into the outdoor heat exchanger; a refrigerant distribution means for distributing the 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 distribution means distributes the refrigerant so that, over a specified period of time, the average value of the outlet temperature or dryness of the refrigerant flow path located at the uppermost part of the outdoor heat exchanger is higher than that of the refrigerant flow path located at the most center of the outdoor heat exchanger.

2. The fan is disposed at a position where the wind speed at a lower end of the outdoor heat exchanger is smaller than that at a center of the outdoor heat exchanger, 2. The air conditioner according to claim 1, wherein, during heating operation, high-pressure refrigerant before passing through an expansion valve flows through the refrigerant passage located at the lowest end of the outdoor heat exchanger.

3. The fan is disposed at a position where the wind speed at a lower end of the outdoor heat exchanger is smaller than that at a center of the outdoor heat exchanger, 2. The air conditioner according to claim 1, wherein the refrigerant distribution means distributes the refrigerant so that, during a predetermined period, the average value of an outlet temperature or dryness fraction of the refrigerant flow path located at the lowermost part of the outdoor heat exchanger is higher than that of the refrigerant flow path located at the most center of the outdoor heat exchanger.

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