Heat exchanger

Abstract

This heat exchanger comprises: a header that has a header opening through which a heat medium flows in or out, and a header flow passage through which the heat medium flows; and three or more branch pipes that are disposed with space therebetween in the direction in which the header flow passage extends, are connected to the header such that one end of each branch pipe protrudes into the header flow passage and communicates with the header flow passage, and have the same pipe diameter. The three or more branch pipes are provided such that the flow resistance of the heat medium between each of the three or more branch pipes and the header flow passage gradually increases from the branch pipe that is the farthest from the header opening among the three or more branch pipes toward the branch pipe that is the closest to the header opening among the three or more branch pipes.

Description

heat exchanger

[0001] This disclosure relates to a heat exchanger. This application claims priority to Japanese Patent Application No. 2023-156027 filed in Japan on September 21, 2023, and Japanese Patent Application No. 2023-155621 filed in Japan on September 21, 2023, the contents of which are incorporated herein by reference.

[0002] A heat exchanger has headers provided at the inlet and outlet sides of a heat medium, and multiple branch pipes arranged in parallel between the inlet header and the outlet header. In such a heat exchanger, the flow rate of the heat medium through the branch pipes connected to the header at a position farther from the header opening through which the heat medium flows in or out tends to be higher in the branch pipes connected to the header at a position closer to the header opening. In response to this, Patent Document 1 discloses a heat exchanger having a header into which a refrigerant flows from one longitudinal end and multiple heat transfer tubes connected in series along the header, in which the cross-sectional areas of the refrigerant passages in the multiple heat transfer tubes gradually increase from one longitudinal end to the other longitudinal end of the header so that the refrigerant flows approximately evenly through the multiple heat transfer tubes.

[0003] Japanese Patent No. 3284904

[0004] However, in the heat exchanger described in Patent Document 1, multiple types of heat transfer tubes with different diameters are used to differentiate the cross-sectional areas of the refrigerant passages of the multiple heat transfer tubes connected to the header. Accordingly, multiple types of holes corresponding to the diameters of the heat transfer tubes must be formed in the header to connect the heat transfer tubes. This poses a problem of time and effort required for manufacturing the header.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a heat exchanger that is easy to manufacture.

[0006] In order to solve the above problems, the heat exchanger according to the present disclosure comprises a header having a header opening through which a heat medium flows in or out and a header flow path through which the heat medium flows, and three or more branch pipes having the same pipe diameter, which are arranged at intervals in the direction in which the header flow path extends, and which are connected to the header so that one end protrudes into the header flow path and communicates with the header flow path, and the three or more branch pipes are arranged so that the flow resistance of the heat medium between each of the three or more branch pipes and the header flow path gradually increases from the branch pipe farthest from the header opening among the three or more branch pipes to the branch pipe closest to the header opening among the three or more branch pipes.

[0007] A heat exchanger according to the present disclosure comprises a header having a header opening through which a heat medium flows in or out and a header flow path through which the heat medium flows, and a plurality of branch pipes having the same pipe diameter, which are arranged at intervals in the direction in which the header flow path extends and are connected to the header so as to communicate with the header flow path, wherein the plurality of branch pipes have constriction sections that narrow the cross-sectional area of ​​the flow path within the plurality of branch pipes, and the plurality of branch pipes are arranged so that the flow resistance of the heat medium within the plurality of branch pipes increases from a branch pipe among the plurality of branch pipes that is farthest from the header opening to a branch pipe among the plurality of branch pipes that is closer to the header opening.

[0008] According to the heat exchanger of the present disclosure, it is possible to provide a heat exchanger that is easy to manufacture.

[0009] FIG. 1 is a diagram illustrating a schematic configuration of a heat exchanger according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view illustrating a connection between a header and a plurality of branch pipes in a heat exchanger according to a first embodiment of the present disclosure. FIG. 3 is a cross-sectional view illustrating a joint between a header and a plurality of branch pipes according to a first modified example of the first embodiment of the present disclosure. FIG. 4 is a cross-sectional view illustrating an arrangement of a plurality of branch pipes relative to a header according to a second modified example of the first embodiment of the present disclosure, viewed from the extension direction of a flow path within the header. FIG. 4 is a cross-sectional view taken along arrows II-II in FIG. 6. FIG. 6 is a cross-sectional view illustrating a connection between a header and a first branch pipe according to a second embodiment of the present disclosure. FIG. 6 is a cross-sectional view taken along arrows III-III in FIG. 6. FIG. 6 is a cross-sectional view illustrating a connection between a header and a third branch pipe according to a second embodiment of the present disclosure, taken along arrows IV-IV in FIG. 6. FIG. 6 is a cross-sectional view illustrating a connection between a header and a fourth branch pipe according to a second embodiment of the present disclosure, taken along arrows V-V in FIG. 6. Fig. 1 is a diagram showing a schematic configuration of a heat exchanger according to a third embodiment of the present disclosure; Fig. 2 is an enlarged cross-sectional view showing a branch pipe of the heat exchanger according to the third embodiment of the present disclosure; Fig. 3 is an enlarged cross-sectional view showing a branch pipe according to a first modified example of the third embodiment of the present disclosure; Fig. 4 is an enlarged cross-sectional view showing a branch pipe according to a second modified example of the third embodiment of the present disclosure.

[0010] Hereinafter, a heat exchanger according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. FIG.

[0011] First Embodiment (Configuration of Heat Exchanger) As shown in Fig. 1 , the heat exchanger 10A includes an inlet header 20A, an outlet header 20B, and a plurality of branch pipes 40. In the heat exchanger 10A, a heat medium flows from the inlet header 20A through the plurality of branch pipes 40 to the outlet header 20B. In this embodiment, the heat medium is a liquid. In this embodiment, the heat medium is water. The heat medium is not limited to water, and may be antifreeze liquid. The heat medium flowing through the heat exchanger 10A is heated or cooled.

[0012] For example, if the heat exchanger 10A in this embodiment is a gas cooler, the heat exchanger 10A cools the gas, while heating the heat medium flowing through the heat exchanger 10A, by performing heat exchange between the heat medium (water) flowing through the multiple branch pipes 40 and the gas flowing outside the multiple branch pipes 40. For example, if the heat exchanger 10A in this embodiment is a gas heater, the heat exchanger 10A heats the gas, while cooling the heat medium flowing through the heat exchanger 10A, by performing heat exchange between the heat medium (water) flowing through the multiple branch pipes 40 and the gas flowing outside the multiple branch pipes 40.

[0013] The heat medium flows into the inlet header 20A from outside the heat exchanger 10A via a supply pipe (not shown). The inlet header 20A has a header main body 21A and a curved pipe section 22A. The header main body 21A consists of a pipe body extending linearly in one direction. One end of the header main body 21A is connected to one end of the curved pipe section 22A. The other end of the header main body 21A is closed. The curved pipe section 22A is curved, for example, in a U-shape. The other end of the curved pipe section 22A is connected to the supply pipe. A header opening 23A is formed at the other end of the curved pipe section 22A, through which the heat medium flows from the supply pipe.

[0014] The inlet header 20A has a header flow path 24A through which the heat medium flows inside the header main body 21A and the curved pipe section 22A. In the inlet header 20A, the heat medium supplied from an external supply pipe flows into the header flow path 24A from a header opening 23A. The heat medium that has flowed into the header flow path 24A of the inlet header 20A branches into multiple branch pipes 40 and flows therethrough.

[0015] The heat medium flows into the outlet header 20B via a plurality of branch pipes 40. The outlet header 20B discharges the heat medium to a discharge pipe (not shown) outside the heat exchanger 10A. The outlet header 20B has a header main body 21B and a curved pipe section 22B. The header main body 21B is made of a pipe body extending linearly in one direction. One end of the header main body 21B is connected to one end of the curved pipe section 22B. The other end of the header main body 21B is closed. The curved pipe section 22B is curved, for example, in a U-shape. The other end of the curved pipe section 22B is connected to the discharge pipe. A header opening 23B is formed at the other end of the curved pipe section 22B, through which the heat medium flows out to the discharge pipe.

[0016] The outlet header 20B has a header flow path 24B through which the heat medium flows inside the header main body 21B and the curved pipe portion 22B. In the outlet header 20B, the heat medium flows into the header flow path 24B after passing through a plurality of branch pipes 40. The outlet header 20B discharges the heat medium that has flowed into the header flow path 24B from a header opening 23B to an external discharge pipe.

[0017] The branch pipes 40 are provided between the inlet header 20A and the outlet header 20B. The branch pipes 40 are provided in parallel between the inlet header 20A and the outlet header 20B. The branch pipes 40 are arranged at intervals in the extension direction of the header flow path 24A of the header body 21A of the inlet header 20A and the header flow path 24B of the header body 21B of the outlet header 20B.

[0018] Three or more branch pipes 40 are provided. In this embodiment, for example, four branch pipes 40 are provided. The number of branch pipes 40 is not limited to four, and may be three, or five or more. In this embodiment, the multiple branch pipes 40 include a first branch pipe 40A, a second branch pipe 40B, a third branch pipe 40C, and a fourth branch pipe 40D. The first branch pipe 40A, the second branch pipe 40B, the third branch pipe 40C, and the fourth branch pipe 40D have the same pipe diameter.

[0019] Each of the branch pipes 40 (first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, fourth branch pipe 40D) is disposed at intervals relative to the inlet header 20A and the outlet header 20B in the direction in which the header flow paths 24A and 24B extend. One end of each of the branch pipes 40 (first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, fourth branch pipe 40D) in the extension direction is joined to the inlet header 20A by brazing, welding, or the like. The other end of each of the branch pipes 40 (first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, fourth branch pipe 40D) in the extension direction is joined to the outlet header 20B by brazing, welding, or the like.

[0020] The heat medium flows from the header flow path 24A of the inlet header 20A into the flow path formed inside each of the branch pipes 40. The heat medium that flows into the flow path formed inside each of the branch pipes 40 flows out to the header flow path 24B of the outlet header 20B. In each of the branch pipes 40, heat exchange occurs between the heat medium flowing through its internal flow path and the gas flowing outside the branch pipe 40. In this embodiment, a gas pipe (not shown) through which gas flows is spirally wrapped around the outer circumferential surface of each of the branch pipes 40. In each of the branch pipes 40, heat exchange occurs between the heat medium flowing through its internal flow path and the gas flowing through the gas pipe wrapped around the outer circumferential surface of the branch pipe 40. Note that the gas does not necessarily have to flow through the gas pipe wrapped around the outer circumferential surface of the branch pipe 40. For example, the gas may flow through the space outside each branch pipe 40, come into contact with the outer surface of each branch pipe 40, and exchange heat with the heat medium flowing within each branch pipe 40.

[0021] The multiple (three or more) branch pipes 40 are arranged so that the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A gradually increases from the branch pipe 40 farthest from the header opening 23A to the branch pipe 40 closest to the header opening 23A along the path along the header flow path 24A. Specifically, of the multiple branch pipes 40, the first branch pipe 40A closest to the header opening 23A along the path along the header flow path 24A has the longest protrusion length La1 into the header flow path 24A. Hereinafter, "close to the header opening 23A" simply means close to the header opening 23A along the path along the header flow path 24A. Furthermore, "far from the header opening 23A" simply means far from the header opening 23A along the path along the header flow path 24A.

[0022] 2 , in this embodiment, one end 401 a, 401 b, 401 c, and 401 d of each of the multiple branch pipes 40 (first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, and fourth branch pipe 40D) protrudes into the header flow path 24A of the inlet header 20A. The one ends 401 a, 401 b, 401 c, and 401 d protrude into the header flow path 24A of the inlet header 20A in the direction in which the first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, and fourth branch pipe 40D extend, i.e., along the radial direction of the header body 21A of the inlet header 20A.

[0023] The branch pipes 40 are arranged such that their protrusion length La into the header flow path 24A gradually increases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A. Of the branch pipes 40, the fourth branch pipe 40D, which is farthest from the header opening 23A, has the shortest protrusion length La4 into the header flow path 24A. From the fourth branch pipe 40D, which is farthest from the header opening 23A, toward the first branch pipe 40A, which is closest to the header opening 23A, the protrusion length La4 of the fourth branch pipe 40D, the protrusion length La3 of the third branch pipe 40C, the protrusion length La2 of the second branch pipe 40B, and the protrusion length La1 of the first branch pipe 40A gradually increase (La4<La3<La2<La1).

[0024] Furthermore, a gap Ga is formed between one end 401a-401d of each of the branch pipes 40 and the inner circumferential surface of the header body 21A that faces the one end 401a-401d with a gap therebetween. The heat exchanger 10A has a gap Ga4 between one end 401d of the fourth branch pipe 40D and the inner circumferential surface of the header body 21A. The heat exchanger 10A has a gap Ga3 between one end 401c of the third branch pipe 40C and the inner circumferential surface of the header body 21A. The heat exchanger 10A has a gap Ga2 between one end 401b of the second branch pipe 40B and the inner circumferential surface of the header body 21A. The heat exchanger 10A has a gap Ga1 between one end 401a of the first branch pipe 40A and the inner circumferential surface of the header body 21A. This gap Ga gradually decreases from the fourth branch pipe 40D, which is farthest from the header opening 23A, toward the first branch pipe 40A, which is closest to the header opening 23A. That is, the gaps Ga4, Ga3, Ga2, and Ga1 gradually decrease from the fourth branch pipe 40D, which is farthest from the header opening 23A, toward the first branch pipe 40A, which is closest to the header opening 23A.

[0025] Each of the branch pipes 40 has an opening 42A that faces the direction in which the branch pipe 40 extends and communicates with the header flow path 24A. In each of the branch pipes 40, the heat transfer medium flows between the branch pipe 40 and the header flow path 24A through the opening 42A. In each of the branch pipes 40, the heat transfer medium flowing through the header flow path 24A flows into the branch pipe 40 through the opening 42A.

[0026] In this case, the branch pipes 40 closer to the header opening 23A have a longer protrusion length La and a smaller gap Ga into the header flow path 24A, making it more difficult for the heat medium flowing through the header flow path 24A to flow into the branch pipes 40 through the opening 42A. Specifically, among the multiple branch pipes 40, the one end 401a of the first branch pipe 40A has the longest protrusion length La and the smallest gap Ga. That is, the first branch pipe 40A is structured such that it is more difficult for the heat medium to flow in from the header flow path 24A than the other branch pipes 40. As a result, of the flow resistances of the heat medium between the multiple branch pipes 40 and the header flow path 24A, the flow resistance between the first branch pipe 40A and the header flow path 24A is the largest. On the other hand, among the multiple branch pipes 40, the one end 401d of the fourth branch pipe 40D has the smallest protrusion length La and the largest gap Ga. That is, the fourth branch pipe 40D is structured so that the heat medium flows more easily from the header flow path 24A into it than the other branch pipes 40. As a result, of the flow resistances of the heat medium between the multiple branch pipes 40 and the header flow path 24A, the flow resistance of the heat medium between the fourth branch pipe 40D and the header flow path 24A is the smallest. Furthermore, the flow resistance of the heat medium in the header flow path 24A gradually increases from the end 401d of the fourth branch pipe 40D, which has the smallest protrusion length La4, to the end 401a of the first branch pipe 40A, which has the longest protrusion length La1, in that order: the end 401d of the fourth branch pipe 40D, the end 401c of the third branch pipe 40C, the end 401b of the second branch pipe 40B, and the end 401a of the first branch pipe 40A. Therefore, the branch pipe 40 that is farther away from the header opening 23A has a smaller protruding length La of the branch pipe 40 into the header flow path 24A, resulting in a smaller flow resistance, and also has a larger gap Ga, which makes it easier for the heat transfer medium flowing through the header flow path 24A to flow into the branch pipe 40 through the opening 42A.

[0027] In this way, by varying the flow resistance of the heat medium between each of the branch pipes 40 and the header flow path 24A among the multiple branch pipes 40, the flow rate of the liquid medium is made uniform. This improves the heat exchange efficiency of the heat exchanger 10A. Furthermore, by improving the heat exchange efficiency of the heat exchanger 10A, the size and cost of the heat exchanger 10A can be reduced. Furthermore, compared to a case where the flow rate of the heat medium in the branch pipes closer to the header opening is higher, which makes the branch pipes more susceptible to corrosion, the heat exchanger 10A can reduce the flow rate of the heat medium in the branch pipes 40 closer to the header opening 23A by making the flow rate of the liquid medium uniform among the multiple branch pipes 40. As a result, corrosion of the branch pipes 40 is suppressed in the heat exchanger 10A.

[0028] (Operations and Effects) According to this embodiment, in the heat exchanger 10A, the three or more branch pipes 40 connected to the inlet header 20A at intervals in the extension direction of the header flow path 24A have a gradually decreasing flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A, from the branch pipe 40 farthest from the header opening 23A to the branch pipe 40 closest to the header opening 23A. As a result, the branch pipes 40 closer to the header opening 23A have a higher flow resistance of the heat medium between the branch pipe 40 and the header flow path 24A than the branch pipes 40 farther from the header opening 23A, making it more difficult for the heat medium to flow from the header flow path 24A into the branch pipe 40. Conversely, the branch pipes 40 farther from the header opening 23A have a lower flow resistance of the heat medium between the branch pipe 40 and the header flow path 24A than the branch pipes 40 closer to the header opening 23A, making it easier for the heat medium to flow from the header flow path 24A into the branch pipe 40. In this way, the flow rate of the heat medium can be made uniform among the plurality of branch pipes 40. In this case, since the three or more branch pipes 40 have the same pipe diameter, it is not necessary to prepare a plurality of types of branch pipes 40; it is sufficient to connect a plurality of branch pipes 40 of the same type to the inlet header 20A. As a result, it is possible to provide a heat exchanger 10A that is easy to manufacture.

[0029] According to one example of this embodiment, three or more branch pipes 40 are provided such that the protrusion length La into the header flow path 24A gradually increases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A. The greater the protrusion length La of the branch pipe 40 into the header flow path 24A, the smaller the gap Ga becomes, and the greater the flow resistance of the heat medium becomes. By providing three or more branch pipes 40 in this manner, the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A can be gradually increased from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A.

[0030] According to one example of the present embodiment, by adjusting the projection length La into the header flow path 24A, the flow resistance of the heat medium between each of the branch pipes 40 and the header flow path 24A can be gradually increased from the branch pipes 40 farthest from the header opening 23A toward the branch pipes 40 closer to the header opening 23A. This makes it possible to provide a heat exchanger 10A that is easy to manufacture.

[0031] According to one example of this embodiment, in each of the three or more branch pipes 40, the heat transfer medium flows between each branch pipe 40 and the header flow path 24A through the opening 42A that faces the extension direction of the branch pipe 40. With this configuration, the greater the protruding length La of the branch pipe 40 into the header flow path 24A, the smaller the distance between the opening 42A and the inner circumferential surface of the header body 21A over the entire opening 42A, making it more difficult for the heat transfer medium to flow over the entire opening 42A. This makes it easy to adjust the flow resistance of the heat transfer medium by changing the protruding length La.

[0032] According to one example of this embodiment, the heat medium is a liquid. In this case, the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A gradually decreases from the branch pipe 40 farthest from the header opening 23A to the branch pipe 40 closest to the header opening 23A, which makes it possible to more effectively equalize the flow rate of the heat medium among the multiple branch pipes 40.

[0033] (First Modification of First Embodiment) In the first embodiment, the branch pipes 40 are configured so that the flow resistance of the heat medium between each of the branch pipes 40 and the header flow path 24A of the inlet header 20A gradually increases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closer to the header opening 23A. In contrast, as a first modification of the first embodiment, as shown in FIG. 3 , the branch pipes 40 of the heat exchanger 10B may be configured so that the flow resistance of the heat medium between each of the branch pipes 40 and the header flow path 24B of the outlet header 20B gradually increases from the branch pipe 40 farthest from the header opening 23B toward the branch pipe 40 closer to the header opening 23B, along the path along the header flow path 24B. Hereinafter, the term "close to the header opening 23B" simply means that the branch pipe 40 is close to the header opening 23B along the path along the header flow path 24B. Furthermore, the term "far from the header opening 23B" simply means that the branch pipe 40 is far from the header opening 23B along the path along the header flow path 24B.

[0034] In this first modified example, the other ends (one ends) 402a, 402b, 402c, and 402d of each of the multiple branch pipes 40 (first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, and fourth branch pipe 40D) protrude into the header flow path 24B of the outlet header 20B. The other ends 402a, 402b, 402c, and 402d protrude into the header flow path 24B of the outlet header 20B in the extending direction of the first branch pipe 40A, second branch pipe 40B, third branch pipe 40C, and fourth branch pipe 40D, i.e., in the radial direction of the header body 21B of the outlet header 20B.

[0035] In this first modified example, the branch pipes 40 are arranged so that the projection length Lb into the header flow path 24B gradually increases from the branch pipe 40 farthest from the header opening 23B toward the branch pipe 40 closest to the header opening 23B. From the fourth branch pipe 40D, which is farthest from the header opening 23B, toward the first branch pipe 40A, which is closest to the header opening 23B, the projection length Lb4 of the fourth branch pipe 40D, the projection length Lb3 of the third branch pipe 40C, the projection length Lb2 of the second branch pipe 40B, and the projection length Lb1 of the first branch pipe 40A gradually increase (Lb4<Lb3<Lb2<Lb1).

[0036] According to the configuration of this first modified example, similar to the first embodiment, the flow resistance of the heat medium between the branch pipe 40 and the header flow path 24B is greater for branch pipes 40 closer to the header opening 23B than for branch pipes 40 farther from the header opening 23B, making it more difficult for the heat medium to flow from the branch pipe 40 to the header flow path 24B. Conversely, the flow resistance of the heat medium between the branch pipe 40 and the header flow path 24B is smaller for branch pipes 40 farther from the header opening 23B than for branch pipes 40 closer to the header opening 23B, making it easier for the heat medium to flow from the branch pipe 40 to the header flow path 24B. In this way, the flow rate of the heat medium can be made uniform among the multiple branch pipes 40. In this case, since three or more branch pipes 40 have the same pipe diameter, it is not necessary to prepare multiple types of branch pipes 40; instead, it is sufficient to connect multiple branch pipes 40 of the same type to the inlet header 20A. As a result, it is possible to provide a heat exchanger 10A that is easy to manufacture.

[0037] 4 and 5 , as a second modification of the first embodiment, in a heat exchanger 10C, the branch pipes 40 may be connected to the inlet header 20A from different directions in the circumferential direction Dc about an axis along the extension direction of the header flow paths 24A. As shown in Fig. 4 , in this second modification, the first branch pipe 40A, the second branch pipe 40B, the third branch pipe 40C, and the fourth branch pipe 40D are connected to the inlet header 20A from different directions in the circumferential direction Dc of the inlet header 20A when viewed from the extension direction of the header flow paths 24A. The first branch pipe 40A, the second branch pipe 40B, the third branch pipe 40C, and the fourth branch pipe 40D are connected to the inlet header 20A from different directions that are 90° apart in the circumferential direction Dc when viewed from the extension direction of the header flow paths 24A. In this second modified example, the second branch pipe 40B is connected to the first branch pipe 40A from a direction offset by 90° to one side of the inlet header 20A in the circumferential direction Dc. The third branch pipe 40C is connected to the second branch pipe 40B from a direction offset by 90° to one side of the inlet header 20A in the circumferential direction Dc. The fourth branch pipe 40D is connected to the third branch pipe 40C from a direction offset by 90° to one side of the inlet header 20A in the circumferential direction Dc.

[0038] According to the configuration of the second modified example, the multiple branch pipes 40 are connected to the inlet header 20A from different directions in the circumferential direction Dc about the axis of the header flow path 24A, which makes it possible to prevent the influence of the branch pipe 40 located upstream in the heat medium flow direction in the header flow path 24A on the flow resistance from extending to other branch pipes 40 located downstream in the flow direction. This makes it possible to more effectively equalize the flow rate of the heat medium among the multiple branch pipes 40.

[0039] Second Embodiment (Configuration of Heat Exchanger) As shown in Fig. 1 , a heat exchanger 10D includes an inlet header 20A, an outlet header 20B, and a plurality of branch pipes 40. Three or more branch pipes 40 are provided. In this embodiment, for example, four branch pipes 40 are provided. In this embodiment, the plurality of branch pipes 40 include a first branch pipe 40P, a second branch pipe 40Q, a third branch pipe 40R, and a fourth branch pipe 40S. The first branch pipe 40P, the second branch pipe 40Q, the third branch pipe 40R, and the fourth branch pipe 40S have the same pipe diameter.

[0040] Each of the branch pipes 40 (first branch pipe 40P, second branch pipe 40Q, third branch pipe 40R, fourth branch pipe 40S) is disposed at intervals relative to the inlet header 20A and the outlet header 20B in the direction in which the header flow paths 24A and 24B extend. One end of each of the branch pipes 40 (first branch pipe 40P, second branch pipe 40Q, third branch pipe 40R, fourth branch pipe 40S) in the extension direction is joined to the inlet header 20A by brazing, welding, or the like. The other end of each of the branch pipes 40 (first branch pipe 40P, second branch pipe 40Q, third branch pipe 40R, fourth branch pipe 40S) in the extension direction is joined to the outlet header 20B by brazing, welding, or the like.

[0041] The multiple (three or more) branch pipes 40 are arranged so that the flow resistance of the heat medium between each of the branch pipes 40 and the header flow path 24A gradually increases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closer to the header opening 23A. As shown in Fig. 6 , each of the multiple branch pipes 40 has an opening 45A that faces in the direction in which the branch pipe 40 extends and communicates with the header flow path 24A. In this embodiment, the multiple (three or more) branch pipes 40 are arranged so that the area of ​​the opening 45A of the branch pipe 40 that communicates with the header flow path 24A gradually decreases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closer to the header opening 23A.

[0042] Each of the branch pipes 40 has an inclined surface 47A at the tip of the branch pipe 40 that protrudes into the header flow path 24A. The inclined surface 47A is inclined with respect to the direction in which the branch pipe 40 extends. In this embodiment, the inclined surface 47A is inclined away from the header opening 23A as it protrudes into the header flow path 24A. The branch pipes 40 are provided such that the inclination angle θa of the inclined surface 47A with respect to the direction in which each branch pipe 40 extends gradually increases from the branch pipe 40 farthest from the header opening 23A to the branch pipe 40 closest to the header opening 23A. Of the inclined surfaces 47A of the branch pipes 40, the inclined surface 47A of the fourth branch pipe 40S has an inclination angle θa4 with respect to the direction in which the fourth branch pipe 40S extends. Of the inclined surfaces 47A of the multiple branch pipes 40, the inclined surface 47A of the third branch pipe 40R has an inclination angle θa3 with respect to the extension direction of the third branch pipe 40R. Of the inclined surfaces 47A of the multiple branch pipes 40, the inclined surface 47A of the second branch pipe 40Q has an inclination angle θa2 with respect to the extension direction of the second branch pipe 40Q. Of the inclined surfaces 47A of the multiple branch pipes 40, the inclined surface 47A of the first branch pipe 40P has an inclination angle θa1 with respect to the extension direction of the first branch pipe 40P.

[0043] Specifically, the inclination angle θa1 of the inclined surface 47A of the first branch pipe 40P, which is closest to the header opening 23A, is the largest among the branch pipes 40. The inclination angle θa4 of the inclined surface 47A of the fourth branch pipe 40S, which is farthest from the header opening 23A, is the smallest among the branch pipes 40. The inclination angles θa4, θa3, θa2, and θa1 gradually increase from the fourth branch pipe 40S, which is farthest from the header opening 23A, to the first branch pipe 40P, which is closest to the header opening 23A (θa4<θa3<θa2<θa1).

[0044] As shown in FIGS. 7A to 7D , the opening 45A of each of the branch pipes 40 is formed on the inclined surface 47A. The opening 45A of each of the branch pipes 40 opens on the inclined surface 47A, forming an elliptical shape when viewed from the direction in which the header flow path 24A extends. The branch pipes 40 are arranged such that the opening dimension Xa of the opening 45A in the longitudinal direction gradually decreases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A. Of the openings 45A of the branch pipes 40, the opening 45A of the fourth branch pipe 40S has an opening dimension Xa4. Of the openings 45A of the branch pipes 40, the opening 45A of the third branch pipe 40R has an opening dimension Xa3. Of the openings 45A of the branch pipes 40, the opening 45A of the second branch pipe 40Q has an opening dimension Xa2. Among the openings 45A of the multiple branch pipes 40, the opening 45A of the first branch pipe 40P has an opening dimension Xa1. From the fourth branch pipe 40S, which is farthest from the header opening 23A, to the first branch pipe 40P, which is closest to the header opening 23A, the opening dimensions Xa4, Xa3, Xa2, and Xa1 gradually decrease (Xa4 > Xa3 > Xa2 > Xa1).

[0045] In this embodiment, the area of ​​the openings 45A of the branch pipes 40 communicating with the header flow path 24A gradually decreases from the branch pipes 40 farthest from the header opening 23A to the branch pipes 40 closest to the header opening 23A. Therefore, the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A increases as the branch pipes 40 are closer to the header opening 23A. In this manner, the flow rate of the liquid medium is made uniform among the branch pipes 40. This improves the heat exchange efficiency of the heat exchanger 10D. Furthermore, the improved heat exchange efficiency of the heat exchanger 10D allows for the miniaturization and cost reduction of the heat exchanger 10D. By making the flow rate of the liquid medium uniform among the branch pipes 40, the flow rate of the heat medium in the branch pipes 40 closest to the header opening 23A can be reduced, thereby suppressing corrosion of the branch pipes 40.

[0046] (Operations and Effects) According to the present embodiment, in the heat exchanger 10D, the three or more branch pipes 40 connected to the inlet header 20A at intervals in the extension direction of the header flow path 24A have a gradually decreasing flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A, from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A. As a result, the branch pipes 40 closer to the header opening 23A have a higher flow resistance of the heat medium between the branch pipe 40 and the header flow path 24A than the branch pipes 40 farther from the header opening 23A, making it more difficult for the heat medium to flow from the header flow path 24A into the branch pipe 40. Conversely, the branch pipes 40 farther from the header opening 23A have a lower flow resistance of the heat medium between the branch pipe 40 and the header flow path 24A than the branch pipes 40 closer to the header opening 23A, making it easier for the heat medium to flow from the header flow path 24A into the branch pipe 40. In this way, the flow rate of the heat medium can be made uniform among the plurality of branch pipes 40. In this case, since the three or more branch pipes 40 have the same pipe diameter, it is not necessary to prepare a plurality of types of branch pipes 40; it is sufficient to connect a plurality of branch pipes 40 of the same type to the inlet header 20A. As a result, it is possible to provide a heat exchanger 10D that is easy to manufacture.

[0047] Furthermore, according to one example of this embodiment, the area of ​​the openings 45A of the branch pipes 40 that communicate with the header flow path 24A gradually decreases from the branch pipes 40 that are farther away from the header opening 23A toward the branch pipes 40 that are closer to the header opening 23A, so the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A increases as the branch pipes 40 are closer to the header opening 23A. Therefore, by arranging the multiple branch pipes 40 so that the area of ​​the openings 45A gradually decreases from the branch pipes 40 that are farther away from the header opening 23A toward the branch pipes 40 that are closer to the header opening 23A, the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24A can be gradually increased from the branch pipes 40 that are farther away from the header opening 23A toward the branch pipes 40 that are closer to the header opening 23A.

[0048] Furthermore, according to one example of this embodiment, by adjusting the area of ​​the opening 45A that communicates with the header flow path 24A, the flow resistance of the heat medium between each of the branch pipes 40 and the header flow path 24A can be gradually increased from the branch pipe 40 that is farther away from the header opening 23A toward the branch pipe 40 that is closer to the header opening 23A. This makes it possible to provide a heat exchanger 10D that is easy to manufacture.

[0049] According to one example of this embodiment, the inclination angle θa of the inclined surface 47A at the tip of the branch pipe 40 gradually increases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A. This allows the area of ​​the opening 45A, which communicates with the header flow path 24A of the branch pipe 40, to gradually decrease from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A for multiple branch pipes 40 having the same pipe diameter. In this way, by varying the inclination angle θa of the inclined surface 47A while using branch pipes 40 with the same internal pipe system, it is possible to provide a heat exchanger 10D in which the area of ​​the opening 45A, which communicates with the header flow path 24A of the branch pipe 40, gradually decreases from the branch pipe 40 farthest from the header opening 23A toward the branch pipe 40 closest to the header opening 23A.

[0050] (Variation of Second Embodiment) In the second embodiment, the areas of the openings 45A in the header flow paths 24A of the inlet header 20A are made different for the multiple branch pipes 40. The flow resistance of the heat medium between each of the branch pipes 40 and the header flow paths 24A of the inlet header 20A is gradually increased from the branch pipes 40 farthest from the header opening 23A toward the branch pipes 40 closer to the header opening 23A. In contrast, as a variation of the second embodiment, as shown in FIG. 8 , the areas of the openings 45B in the header flow paths 24B of the outlet header 20B may be made different for the multiple branch pipes 40 of the heat exchanger 10E. The flow resistance of the heat medium between each of the branch pipes 40 and the header flow paths 24B of the outlet header 20B may be gradually increased from the branch pipes 40 farthest from the header opening 23B toward the branch pipes 40 closer to the header opening 23B.

[0051] In this modified example, each of the multiple branch pipes 40 has an inclined surface 47B at the tip of the branch pipe 40 that protrudes into the header flow path 24B. The inclined surface 47B is inclined with respect to the direction in which the branch pipe 40 extends. In this modified example, the inclined surface 47B is inclined away from the header opening 23B as it protrudes into the header flow path 24B. The multiple (three or more) branch pipes 40 are provided such that the inclination angle θb of the inclined surface 47B with respect to the direction in which each branch pipe 40 extends gradually increases from the branch pipe 40 that is farthest from the header opening 23B toward the branch pipe 40 that is closest to the header opening 23B.

[0052] In this modification, opening 45B is formed on inclined surface 47B in each of the plurality of branch pipes 40. The plurality of branch pipes 40 are arranged such that the opening dimension in the longitudinal direction of opening 45B gradually decreases from the branch pipe 40 farthest from header opening 23B toward the branch pipe 40 closest to header opening 23B.

[0053] In this modified example, the area of ​​the opening 45B that communicates with the header flow path 24B of the branch pipes 40 gradually decreases from the branch pipe 40 that is farthest from the header opening 23B to the branch pipe 40 that is closest to the header opening 23B, so the flow resistance of the heat medium between each branch pipe 40 and the header flow path 24B increases as the branch pipe 40 is closer to the header opening 23B.

[0054] According to the configuration of this modified example, similar to the second embodiment, the flow rate of the heat medium can be made uniform among the plurality of branch pipes 40. In this case, since the three or more branch pipes 40 have the same pipe diameter, it is not necessary to prepare a plurality of types of branch pipes 40; instead, it is sufficient to connect a plurality of branch pipes 40 of the same type to the outlet header 20B. As a result, it is possible to provide a heat exchanger 10E that is easy to manufacture.

[0055] (Other Modifications of the Embodiment) In the first embodiment, the protrusion lengths La, Lb of the first branch pipe 40A are the longest among the protrusion lengths La, Lb of the multiple branch pipes 40. However, the heat exchangers 10A, 10B may be configured in any manner as long as the gap between the first branch pipe 40A closest to the header opening 23A, 23B and the inner circumferential surface of the header body 21A, 21B is the smallest among the gaps between the multiple branch pipes 40 and the inner circumferential surface of the header body 21A, 21B. As a modification, in the heat exchanger 10A, the protrusion length La of the first branch pipe 40A closest to the header opening 23A may be 0, i.e., the first branch pipe 40A does not protrude into the header flow path 24A. As another modification, in the heat exchanger 10B, the protrusion length Lb of the first branch pipe 40A closest to the header opening 23B may be 0, i.e., the first branch pipe 40A does not protrude into the header flow path 24B.

[0056] In the second embodiment described above, the inclined surfaces 47A, 47B and the openings 45A, 45B face toward the header openings 23A, 23B with respect to the paths along the header flow paths 24A, 24B, but this is not limiting. As a modified example, the inclined surfaces 47A and the openings 45A may face in a direction different from the header opening 23A with respect to the paths along the header flow path 24A, for example, on a side away from the header opening 23A with respect to the paths along the header flow path 24A. As another modified example, the inclined surfaces 47B and the openings 45B may face in a direction different from the header opening 23B with respect to the paths along the header flow path 24B, for example, on a side away from the header opening 23B with respect to the paths along the header flow path 24B.

[0057] In the second embodiment, the inclination angles θa and θb of the first branch pipe 40P are the largest among the inclination angles θa and θb of the multiple branch pipes 40. However, the inclination angles θa and θb may be any angle as long as the area of ​​the openings 45A and 45B of the first branch pipe 40P closest to the header openings 23A and 23B is the smallest among the areas of the openings 45A and 45B of the multiple branch pipes 40. As a modified example, the inclination angle θa of the inclined surface 47A of the first branch pipe 40P may be 90°. That is, the inclined surface 47A of the first branch pipe 40P may be perpendicular to the extension direction of the branch pipe 40. In this case, the opening 45A of the first branch pipe 40P is a perfect circle. As another modified example, the inclination angle θb of the inclined surface 47B of the first branch pipe 40P may be 90°. That is, the inclined surface 47B of the first branch pipe 40P may be perpendicular to the extension direction of the branch pipe 40. In this case, the opening 45B in the first branch pipe 40P is a perfect circle.

[0058] As a further modification, it is also possible to appropriately combine the configurations shown in the first embodiment and its modifications with the configurations shown in the second embodiment and its modifications.

[0059] Third Embodiment Hereinafter, a heat exchanger according to a third embodiment of the present disclosure will be described with reference to FIGS.

[0060] (Configuration of Heat Exchanger) As shown in Fig. 9, the heat exchanger 110A includes an inlet header 120A, an outlet header 120B, and a plurality of branch pipes 140. In the heat exchanger 110A, a heat medium flows from the inlet header 120A through the plurality of branch pipes 140 to the outlet header 120B. In this embodiment, the heat medium is a liquid. In this embodiment, the heat medium is water. The heat medium is not limited to water, and may be antifreeze liquid. The heat exchanger 110A heats or cools the heat medium.

[0061] For example, if the heat exchanger 110A in this embodiment is a gas cooler, the heat exchanger 110A cools the gas, while heating the heat medium flowing through the heat exchanger 110A, by performing heat exchange between a heat medium (water) flowing through the multiple branch pipes 140 and a gas flowing outside the multiple branch pipes 140. For example, if the heat exchanger 110A in this embodiment is a gas heater, the heat exchanger 110A heats the gas, while cooling the heat medium flowing through the heat exchanger 110A, by performing heat exchange between a heat medium (water) flowing through the multiple branch pipes 140 and a gas flowing outside the multiple branch pipes 140.

[0062] The heat medium flows into the inlet header 120A from outside the heat exchanger 110A via a supply pipe (not shown). The inlet header 120A has a header main body 121A and a curved pipe section 122A. The header main body 121A is made of a pipe extending linearly in one direction. One end of the header main body 121A is connected to one end of the curved pipe section 122A. The other end of the header main body 121A is closed. The curved pipe section 122A is curved, for example, in a U-shape. The other end of the curved pipe section 122A is connected to the supply pipe. A header opening 123A is formed at the other end of the curved pipe section 122A, through which the heat medium flows from the supply pipe.

[0063] The inlet header 120A has a header flow path 124A through which the heat medium flows inside the header main body 121A and the curved pipe section 122A. In the inlet header 120A, the heat medium supplied from an external supply pipe flows into the header flow path 124A from a header opening 123A. The heat medium that has flowed into the header flow path 124A of the inlet header 120A branches into multiple branch pipes 140 and flows therethrough.

[0064] The heat medium flows into the outlet header 120B via a plurality of branch pipes 140. The outlet header 120B discharges the heat medium to a discharge pipe (not shown) outside the heat exchanger 110A. The outlet header 120B has a header main body 121B and a curved pipe portion 122B. The header main body 121B is composed of a pipe extending linearly in one direction. One end of the header main body 121B is connected to one end of the curved pipe portion 122B. The other end of the header main body 121B is closed. The curved pipe portion 122B is curved, for example, in a U-shape. The other end of the curved pipe portion 122B is connected to the discharge pipe. A header opening 123B is formed at the other end of the curved pipe portion 122B, through which the heat medium flows out to the discharge pipe.

[0065] The outlet header 120B has a header flow path 124B through which the heat medium flows inside the header main body 121B and the curved pipe portion 122B. In the outlet header 120B, the heat medium flows into the header flow path 124B after passing through a plurality of branch pipes 140. The outlet header 120B discharges the heat medium that has flowed into the header flow path 124B from a header opening 123B to an external discharge pipe.

[0066] The branch pipes 140 are provided between the inlet header 120A and the outlet header 120B. The branch pipes 140 are provided in parallel between the inlet header 120A and the outlet header 120B. The branch pipes 140 are arranged at intervals in the extension direction of the header flow path 124A of the header body 121A of the inlet header 120A and the header flow path 124B of the header body 121B of the outlet header 120B.

[0067] As shown in Figures 9 and 10 , a plurality of branch pipes 140 are provided. In this embodiment, for example, four branch pipes 140 are provided. The number of branch pipes 140 is not limited to four, and may be two, three, five or more. In this embodiment, the plurality of branch pipes 140 includes a first branch pipe 140A, a second branch pipe 140B, a third branch pipe 140C, and a fourth branch pipe 140D. The first branch pipe 140A, the second branch pipe 140B, the third branch pipe 140C, and the fourth branch pipe 140D have the same pipe diameter (outer diameter D, inner diameter d0: see Figure 10 ).

[0068] Each of the branch pipes 140 (first branch pipe 140A, second branch pipe 140B, third branch pipe 140C, fourth branch pipe 140D) is disposed at intervals relative to the inlet header 120A and the outlet header 120B in the direction in which the header flow paths 124A and 124B extend. One end of each of the branch pipes 140 (first branch pipe 140A, second branch pipe 140B, third branch pipe 140C, fourth branch pipe 140D) in the extension direction is joined to the inlet header 120A by brazing, welding, or the like. The other end of each of the branch pipes 140 (first branch pipe 140A, second branch pipe 140B, third branch pipe 140C, fourth branch pipe 140D) in the extension direction is joined to the outlet header 120B by brazing, welding, or the like.

[0069] The heat medium flows into the flow passages formed inside each of the branch pipes 140 from the header flow passage 124A of the inlet header 120A. The heat medium that flows into the flow passages formed inside each of the branch pipes 140 flows out to the header flow passage 124B of the outlet header 120B. In each of the branch pipes 140, heat exchange occurs between the heat medium flowing through its internal flow passage and the gas flowing outside the branch pipe 140. In this embodiment, a gas pipe (not shown) through which gas flows is spirally wrapped around the outer circumferential surface of each of the branch pipes 140. In each of the branch pipes 140, heat exchange occurs between the heat medium flowing through its internal flow passage and the gas flowing through the gas pipe wrapped around the outer circumferential surface of the branch pipe 140. Note that the gas does not necessarily have to flow through the gas pipe wrapped around the outer circumferential surface of the branch pipe 140. For example, the gas may flow through the space outside each branch pipe 140, come into contact with the outer surface of each branch pipe 140, and exchange heat with the heat medium flowing within each branch pipe 140.

[0070] The plurality of branch pipes 140 are provided such that the flow resistance of the heat medium in the plurality of branch pipes 140, with respect to the path along header flow path 124A, gradually increases from the branch pipe 140 that is farther away from header opening 123A toward the branch pipe 140 that is closer to header opening 123A. Furthermore, the plurality of branch pipes 140 are provided such that the flow resistance of the heat medium in the plurality of branch pipes 140, with respect to the path along header flow path 124B, gradually increases from the branch pipe 140 that is farther away from header opening 123B toward the branch pipe 140 that is closer to header opening 123B.

[0071] Hereinafter, "close to the header opening 123A" simply means that it is close to the header opening 123A with respect to the path along the header flow path 124A. Furthermore, hereinafter, "far from the header opening 123A" simply means that it is far from the header opening 123A with respect to the path along the header flow path 124A. Furthermore, hereinafter, "close to the header opening 123B" simply means that it is close to the header opening 123B with respect to the path along the header flow path 124B. Furthermore, hereinafter, "far from the header opening 123B" simply means that it is far from the header opening 123B with respect to the path along the header flow path 124B.

[0072] The plurality of branch pipes 140 each have a throttle portion 151 that throttles the cross-sectional area of ​​the flow path within the plurality of branch pipes 140. At least one of the plurality of branch pipes 140 has the throttle portion 151. In this embodiment, of the plurality of branch pipes 140, at least the first branch pipe 140A that is closest to the header opening 123A has the throttle portion 151. Hereinafter, the "throttle portion 151" refers to a series of portions of each branch pipe 140 whose inner diameter is smaller than the inner diameter d0 of the portion other than the throttle portion 151.

[0073] Specifically, of the multiple branch pipes 140, the first branch pipe 140A closest to the header opening 123A has a throttle portion 151A as the throttle portion 151. Of the multiple branch pipes 140, the second branch pipe 140B second closest to the header opening 123A has a throttle portion 151B as the throttle portion 151. Of the multiple branch pipes 140, the third branch pipe 140C third closest to the header opening 123A has a throttle portion 151C as the throttle portion 151.

[0074] Each throttle section 151 throttles the cross-sectional area of ​​the flow path in the corresponding branch pipe 140. Each throttle section 151 is formed by narrowing the pipe diameter of the branch pipe 140 at a part of the branch pipe 140 in the extension direction.

[0075] The constricted portion 151A is formed by appropriately drawing the pipe forming the first branch pipe 140A, and has an inner diameter smaller than the inner diameter d0 of the portion other than the constricted portion 151A. The constricted portion 151B is formed by appropriately drawing the pipe forming the second branch pipe 140B, and has an inner diameter smaller than the inner diameter d0 of the portion other than the constricted portion 151B. The constricted portion 151C is formed by appropriately drawing the pipe forming the third branch pipe 140C, and has an inner diameter smaller than the inner diameter d0 of the portion other than the constricted portion 151C. In this embodiment, of the multiple branch pipes 140, the fourth branch pipe 140D, which is farthest from the header opening 123A, does not include a constricted portion 151 and is formed as a straight pipe with an inner diameter d0 that is constant throughout the extension direction of the fourth branch pipe 140D.

[0076] Hereinafter, "the inner diameter of the restrictor portion 151" refers to the inner diameter at the smallest part of the entire restrictor portion 151. In other words, "the inner diameter of the restrictor portion 151A" refers to the inner diameter at the smallest part of the entire restrictor portion 151A. Furthermore, "the inner diameter of the restrictor portion 151B" refers to the inner diameter at the smallest part of the entire restrictor portion 151B. Furthermore, "the inner diameter of the restrictor portion 151C" refers to the inner diameter at the smallest part of the entire restrictor portion 151C.

[0077] In this embodiment, the inner diameters d of the throttle portions 151 are varied among the branch pipes 140, so that the flow resistance of the heat medium in the branch pipes 140 gradually increases from the branch pipes 140 farthest from the header opening 123A toward the branch pipes 140 closest to the header opening 123A. The first branch pipe 140A closest to the header opening 123A has a throttle portion 151A with an inner diameter d1. The second branch pipe 140B, which is second closest to the header opening 123A, has a throttle portion 151B with an inner diameter d2. The third branch pipe 140C, which is third closest to the header opening 123A, has a throttle portion 151C with an inner diameter d3. The inner diameter d3 of the throttle portion 151C, the inner diameter d2 of the throttle portion 151B, and the inner diameter d1 of the throttle portion 151A are set to decrease in this order.

[0078] In this embodiment, the first branch pipe 140A closest to the header opening 123A is also the branch pipe 140 closest to the header opening 123B among the multiple branch pipes 140. In addition, in this embodiment, the second branch pipe 140B second closest to the header opening 123A is also the branch pipe 140 second closest to the header opening 123B among the multiple branch pipes 140. In addition, in this embodiment, the third branch pipe 140C third closest to the header opening 123A is also the branch pipe 140 third closest to the header opening 123B among the multiple branch pipes 140. In addition, in this embodiment, the fourth branch pipe 140D farthest from the header opening 123A is also the branch pipe 140 farthest from the header opening 123B among the multiple branch pipes 140.

[0079] That is, of the two first branch pipes 140A and second branch pipes 140B adjacent to each other in the direction in which the header flow paths 124A and 124B extend, the inner diameter d1 of the throttle portion 151A of the first branch pipe 140A located closer to the header openings 123A and 123B is smaller than the inner diameter d2 of the throttle portion 151B of the second branch pipe 140B located farther from the header openings 123A and 123B. Of the two second branch pipes 140B and third branch pipes 140C adjacent to each other in the direction in which the header flow paths 124A and 124B extend, the inner diameter d2 of the throttle portion 151B of the second branch pipe 140B located closer to the header openings 123A and 123B is smaller than the inner diameter d3 of the throttle portion 151C of the third branch pipe 140C located farther from the header openings 123A and 123B. Of the two adjacent third branch pipes 140C and fourth branch pipes 140D in the direction in which the header flow paths 124A and 124B extend, the inner diameter d3 of the constriction section 151C of the third branch pipe 140C located closer to the header openings 123A and 123B is smaller than the inner diameter d0 of the fourth branch pipe 140D located away from the header openings 123A and 123B and not having the constriction section 151C.

[0080] As shown in Fig. 10 , in this embodiment, one end of each of the multiple branch pipes 140 (first branch pipe 140A, second branch pipe 140B, third branch pipe 140C, and fourth branch pipe 140D) protrudes into the header flow path 124A of the inlet header 120A. Each of the multiple branch pipes 140 has an opening 142A that faces the direction in which the branch pipe 140 extends and communicates with the header flow path 124A. In each of the multiple branch pipes 140, the heat transfer medium flows between the branch pipe 140 and the header flow path 124A through the opening 142A. In each of the multiple branch pipes 140, the heat transfer medium flowing through the header flow path 124A flows into the branch pipe 140 through the opening 142A.

[0081] At this time, the closer the branch pipe 140 is to header opening 123A, the smaller the inner diameter d (d1 to d3) of the throttle section 151 is, and therefore the greater the flow resistance of the heat medium in the branch pipe 140, making it more difficult for the heat medium circulating through the header flow path 124A to flow into the branch pipe 140 through opening 142A. Furthermore, the farther the branch pipe 140 is from header opening 123A, the larger the inner diameter d of the throttle section 151 is, and since the fourth branch pipe 140D is not provided with a throttle section 151, the smaller the flow resistance of the heat medium in the branch pipe 140 is, and therefore the more easily the heat medium circulating through the header flow path 124A flows into the branch pipe 140 through opening 142A.

[0082] Similarly, the closer the branch pipe 140 is to header opening 123B, the smaller the inner diameter d (d1 to d3) of the throttle section 151, and therefore the greater the flow resistance of the heat medium in the branch pipe 140, making it more difficult for the heat medium flowing in the branch pipe 140 to flow out into the header flow path 124B through the opening. Also, the farther the branch pipe 140 is from header opening 123B, the larger the inner diameter d of the throttle section 151 is, and since the fourth branch pipe 140D is not provided with a throttle section 151, the smaller the flow resistance of the heat medium in the branch pipe 140, making it more likely for the heat medium flowing in the branch pipe 140 to flow out into the header flow path 124B through the opening.

[0083] In this way, by varying the flow resistance of the heat medium in the multiple branch pipes 140 among the multiple branch pipes 140, the flow rate of the liquid medium is made uniform. This improves the heat exchange efficiency of the heat exchanger 110A. Furthermore, by improving the heat exchange efficiency of the heat exchanger 110A, the size and cost of the heat exchanger 110A can be reduced. Furthermore, compared to a case where the flow rate of the heat medium in the branch pipes closer to the header opening is higher, which makes the branch pipes 140 more susceptible to corrosion, the heat exchanger 110A can reduce the flow rate of the heat medium in the branch pipes 140 closer to the header openings 123A and 123B by making the flow rate of the liquid medium uniform among the multiple branch pipes 140. As a result, corrosion of the branch pipes 140 is suppressed.

[0084] (Operations and Effects) According to the present embodiment, in the heat exchanger 110A, the plurality of branch pipes 140 are provided with the throttle sections 151, so that the flow resistance of the heat medium in the plurality of branch pipes 140 gradually increases from the branch pipes 140 that are farther from the header openings 123A and 123B toward the branch pipes 140 that are closer to the header openings 123A and 123B. As a result, the flow resistance of the heat medium in the branch pipes 140 that are closer to the header openings 123A and 123B is greater than that in the branch pipes 140 that are farther from the header openings 123A and 123B, and therefore it becomes more difficult for the heat medium to flow from the header flow paths 124A and 124B into the branch pipes 140. Conversely, the flow resistance of the heat medium in the branch pipes 140 farther from the header openings 123A and 123B is smaller than that in the branch pipes 140 closer to the header openings 123A and 123B, making it easier for the heat medium to flow from the header flow paths 124A and 124B into the branch pipes 140. In this way, the flow rate of the heat medium can be made uniform among the multiple branch pipes 140. Since the multiple branch pipes 140 have the same pipe diameter (outer diameter D), for example, there is no need to form holes in the inlet-side header 120A and the outlet-side header 120B to connect branch pipes 140 with different pipe diameters. This simplifies the structure of the inlet-side header 120A and the outlet-side header 120B. As a result, it is possible to provide a heat exchanger 110A that is easy to manufacture.

[0085] Furthermore, according to one example of this embodiment, the inner diameter d of the throttle portion 151 in the branch pipe 140 arranged closer to the header openings 123A and 123B is smaller than the inner diameter d of the throttle portion 151 in the branch pipe 140 arranged further from the header openings 123A and 123B. This makes it possible to increase the flow resistance of the heat medium in the multiple branch pipes 140 from the branch pipe 140 farther from the header openings 123A and 123B toward the branch pipe 140 closer to the header openings 123A and 123B, while using branch pipes 140 having the same pipe diameter (outer diameter D).

[0086] Furthermore, according to one example of this embodiment, the flow resistance of the heat medium in the three or more branch pipes 140 can be gradually increased from the branch pipes 140 farthest from the header openings 123A and 123B toward the branch pipes 140 closer to the header openings 123A and 123B. Therefore, the flow rate of the heat medium can be made uniform among the three or more branch pipes 140.

[0087] In the above embodiment, the throttle sections 151A to 151C having different inner diameters d are provided in order to gradually increase the flow resistance of the heat medium in the branch pipes 140 from the branch pipes 140 farthest from the header opening 123A toward the branch pipes 140 closest to the header opening 123A, but this is not limiting. Modified examples are shown below.

[0088] (First Modification of Third Embodiment) As a first modification of the third embodiment, as shown in FIG. 11 , in a heat exchanger 110B, the branch pipes 140 may each have a throttle portion 152 that narrows the cross-sectional flow area within the branch pipes 140. That is, at least one of the branch pipes 140 may have the throttle portion 152. In this first modification, at least the first branch pipe 140A, which is closest to the header opening 123A, of the branch pipes 140, has the throttle portion 152. Specifically, of the branch pipes 140, the first branch pipe 140A closest to the header opening 123A, the second branch pipe 140B second closest to the header opening 123A, and the third branch pipe 140C third closest to the header opening 123A may each have the throttle portion 152. Each throttle portion 152 narrows the cross-sectional flow area within the corresponding branch pipe 140. Each of the throttled portions 152 is formed by narrowing the diameter of the branch pipe 140 at a portion of the branch pipe 140 in the extension direction. In this first modified example, of the multiple branch pipes 140, the fourth branch pipe 140D, which is the farthest from the header opening 123A, does not include a throttled portion 152 and is formed as a straight pipe with an inner diameter d0 that is constant throughout the entire extension direction of the fourth branch pipe 140D. Hereinafter, the "length of the throttled portion 152" refers to the length of the portion of each branch pipe 140 where the inner diameter is smaller than the inner diameter d0 of the portion other than each of the throttled portions 152.

[0089] In this first variant, the length L of the constriction section 152 in the extension direction of the branch pipes 140 is made different for the multiple branch pipes 140, so that the flow resistance of the heat medium within the multiple branch pipes 140 gradually increases from the branch pipes 140 farther from the header opening 123A to the branch pipes 140 closer to the header opening 123A.

[0090] The first branch pipe 140A closest to the header opening 123A has a throttle portion 152A with a length L1 in its extension direction. The second branch pipe 140B, second closest to the header opening 123A, has a throttle portion 152B with a length L2 in its extension direction. The third branch pipe 140C, third closest to the header opening 123A, has a throttle portion 152C with a length L3 in its extension direction. The lengths L3, L2, and L1 of the throttle portions 152C, 152B, and 152A increase in this order.

[0091] That is, of the two first and second branch pipes 140A and 140B adjacent to each other in the direction in which the header flow paths 124A and 124B extend, the length L1 of the throttle portion 152A of the first branch pipe 140A located closer to the header openings 123A and 123B is greater than the length L2 of the throttle portion 152B of the second branch pipe 140B located farther from the header openings 123A and 123B. Of the two second and third branch pipes 140B and 140C adjacent to each other in the direction in which the header flow paths 124A and 124B extend, the length L2 of the throttle portion 152B of the second branch pipe 140B located closer to the header openings 123A and 123B is greater than the length L3 of the throttle portion 152C of the third branch pipe 140C located farther from the header openings 123A and 123B. Of the two adjacent third and fourth branch pipes 140C and 140D in the direction in which the header flow paths 124A and 124B extend, the length L3 of the constriction section 152C of the third branch pipe 140C located closer to the header openings 123A and 123B is greater than the length of the constriction section 152 of the fourth branch pipe 140D located further away from the header openings 123A and 123B and not having the constriction section 152 (the length is 0 because the constriction section 152 is not provided).

[0092] In this way, the closer the branch pipe 140 is to the header opening 123A, the greater the length L of the throttle section 152, and therefore the greater the flow resistance of the heat medium within the branch pipe 140. As a result, the closer the branch pipe 140 is to the header opening 123A, the more difficult it is for the heat medium flowing through the header flow path 124A to flow into the branch pipe 140 through the opening 142A. Furthermore, the farther the branch pipe 140 is from the header opening 123A, the smaller the flow resistance of the heat medium within the branch pipe 140, and therefore the more easily the heat medium flowing through the header flow path 124A will flow into the branch pipe 140 through the opening 142A.

[0093] Hereinafter, the "inner diameter of the restrictor portion 152A" refers to the smallest inner diameter of the entire restrictor portion 152A. The "inner diameter of the restrictor portion 152B" refers to the smallest inner diameter of the entire restrictor portion 152B. The "inner diameter of the restrictor portion 152C" refers to the smallest inner diameter of the entire restrictor portion 152C.

[0094] For example, the throttle portion 152 of the branch pipe 140 that is far from the header openings 123A and 123B and the throttle portion 152 of the branch pipe 140 that is close to the header openings 123A and 123B may have the same inner diameter d11. Furthermore, the throttle portion 152A, the throttle portion 152B, and the throttle portion 152C may have the same inner diameter d11.

[0095] (Operations and Effects) According to this first modified example, in the heat exchanger 110B, similar to the above embodiment, the branch pipes 140 are provided with throttle portions 152 so that the flow resistance of the heat medium in the branch pipes 140 gradually increases from the branch pipes 140 farthest from the header openings 123A and 123B to the branch pipes 140 closest to the header openings 123A and 123B. This allows for uniform flow rates of the heat medium among the branch pipes 140. Because the branch pipes 140 have the same pipe diameter (outer diameter D), there is no need to form holes in the inlet header 120A and the outlet header 120B to connect branch pipes 140 of different diameters. As a result, it is possible to provide a heat exchanger 110B that is easy to manufacture.

[0096] Furthermore, according to this first modified example, the length L of the throttled portion 152 in the branch pipe 140 located closer to the header openings 123A and 123B is greater than the length L of the throttled portion 152 in the branch pipe 140 located further from the header openings 123A and 123B. This makes it possible to increase the flow resistance of the heat medium in the multiple branch pipes 140 from the branch pipe 140 located further from the header openings 123A and 123B toward the branch pipe 140 closer to the header openings 123A and 123B, while using branch pipes 140 having the same pipe diameter (outer diameter D).

[0097] Furthermore, according to one example of the first modified example, the throttle portions 152 of the branch pipes 140 that are farther from the header openings 123A and 123B and the throttle portions 152 of the branch pipes 140 that are closer to the header openings 123A and 123B have the same inner diameter, so that the multiple throttle portions 152 can be manufactured using the same process. This makes it possible to provide a heat exchanger 110B that is easy to manufacture.

[0098] Furthermore, according to one example of the first modified example, the flow resistance of the heat medium in the three or more branch pipes 140 can be gradually increased from the branch pipes 140 farthest from the header openings 123A and 123B toward the branch pipes 140 closer to the header openings 123A and 123B. Therefore, the flow rate of the heat medium can be made uniform among the three or more branch pipes 140.

[0099] (Second Modification of Third Embodiment) As a second modification of the third embodiment, as shown in FIG. 12 , in a heat exchanger 110C, the branch pipes 140 may each have a throttle portion 153 that throttles the cross-sectional flow area within the branch pipes 140. That is, at least one of the branch pipes 140 may have the throttle portion 153. In this second modification, at least the first branch pipe 140A, which is closest to the header opening 123A, of the branch pipes 140, has the throttle portion 153. Specifically, of the branch pipes 140, the first branch pipe 140A closest to the header opening 123A, the second branch pipe 140B second closest to the header opening 123A, and the third branch pipe 140C third closest to the header opening 123A may each have the throttle portion 153. Each throttle portion 153 throttles the cross-sectional flow area within the corresponding branch pipe 140. Each of the throttled portions 153 is formed by narrowing the diameter of the branch pipe 140 at a portion in the extension direction of the branch pipe 140. In the second modified example, of the multiple branch pipes 140, the fourth branch pipe 140D, which is the farthest from the header opening 123A, does not have a throttled portion 153 and is formed as a straight pipe with an inner diameter d0 that is constant throughout the entire extension direction of the fourth branch pipe 140D.

[0100] In this second modification, the number N of throttle portions 153 is varied among the branch pipes 140, so that the flow resistance of the heat medium in the branch pipes 140 gradually increases from the branch pipes 140 farthest from the header opening 123A toward the branch pipes 140 closest to the header opening 123A. The first branch pipe 140A closest to the header opening 123A has, for example, three throttle portions 153A (number N = 3) in its extension direction. The second branch pipe 140B second closest to the header opening 123A has, for example, two throttle portions 153B (number N = 2) in its extension direction. The third branch pipe 140C third closest to the header opening 123A has, for example, one throttle portion 153C (number N = 1) in its extension direction. The number N of throttle portions 153C, the number N of throttle portions 153B, and the number N of throttle portions 153A are set to increase sequentially in this order.

[0101] That is, of the two first branch pipes 140A and second branch pipes 140B adjacent to each other in the direction in which the header flow paths 124A and 124B extend, the number N (N=3) of the throttle portions 153A of the first branch pipe 140A located closer to the header openings 123A and 123B is greater than the number N (N=2) of the throttle portions 153B of the second branch pipe 140B located farther from the header openings 123A and 123B. Of the two second branch pipes 140B and third branch pipes 140C adjacent to each other in the direction in which the header flow paths 124A and 124B extend, the number N (N=2) of the throttle portions 153B of the second branch pipe 140B located closer to the header openings 123A and 123B is greater than the number N (N=1) of the throttle portions 153C of the third branch pipe 140C located farther from the header openings 123A and 123B. Of the two adjacent third branch pipes 140C and fourth branch pipes 140D in the direction in which the header flow paths 124A and 124B extend, the number N (N = 1) of throttling sections 153C of the third branch pipe 140C located closer to the header openings 123A and 123B is greater than the number N (N = 0 because no throttling section 153 is provided) of throttling sections 153C of the fourth branch pipe 140D located further away from the header openings 123A and 123B and not having a throttling section 153.

[0102] In this way, the closer the branch pipe 140 is to the header opening 123A, the greater the number N of throttle portions 153, and therefore the greater the flow resistance of the heat medium within the multiple branch pipes 140. As a result, the closer the branch pipe 140 is to the header opening 123A, the more difficult it is for the heat medium flowing through the header flow path 124A to flow into the branch pipe 140 through the opening 142A. Furthermore, the farther the branch pipe 140 is from the header opening 123A, the smaller the flow resistance of the heat medium within the branch pipe 140, and therefore the more easily the heat medium flowing through the header flow path 124A will flow into the branch pipe 140 through the opening 142A.

[0103] Hereinafter, "the inner diameter of restrictor 153A" refers to the inner diameter at the smallest part of the entirety of each of the three restrictor sections 153A. Also, "the inner diameter of restrictor section 153B" refers to the inner diameter at the smallest part of the entirety of each of the two restrictor sections 153A. Also, "the inner diameter of restrictor section 153C" refers to the inner diameter at the smallest part of the entirety of restrictor section 153C.

[0104] For example, the throttle portions 153 of the branch pipes 140 that are far from the header openings 123A and 123B and the throttle portions 153 of the branch pipes 140 that are close to the header openings 123A and 123B may have the same inner diameter. Furthermore, the three throttle portions 153A may have the same inner diameter d12. Furthermore, the two throttle portions 153B may have the same inner diameter d12. Furthermore, the inner diameters d12 of the three throttle portions 153A, the two throttle portions 153B, and the one throttle portion 153C may all be the same.

[0105] (Operations and Effects) According to the second modified example, in the heat exchanger 110C, similar to the above embodiment, the branch pipes 140 are provided with the throttle portions 153 so that the flow resistance of the heat medium in the branch pipes 140 gradually increases from the branch pipes 140 farthest from the header openings 123A and 123B toward the branch pipes 140 closest to the header openings 123A and 123B. This allows for uniform flow rates of the heat medium among the branch pipes 140. Because the branch pipes 140 have the same diameter, there is no need to form holes in the header to connect branch pipes 140 of different diameters. As a result, it is possible to provide a heat exchanger 110C that is easy to manufacture.

[0106] Furthermore, according to the second modified example, the number N of throttle portions 153 in branch pipes 140 arranged closer to header openings 123A and 123B is made greater than the number N of throttle portions 153 in branch pipes 140 arranged further from header openings 123A and 123B. This makes it possible to increase the flow resistance of the heat medium in the multiple branch pipes 140 from the branch pipes 140 farther from header openings 123A and 123B toward the branch pipes 140 closer to header openings 123A and 123B, while using branch pipes 140 having the same pipe diameter (outer diameter D).

[0107] Furthermore, according to one example of the second modified example, the throttle portions 153 of the branch pipes 140 that are farther from the header openings 123A and 123B and the throttle portions 153 of the branch pipes 140 that are closer to the header openings 123A and 123B have the same inner diameter, so that the multiple throttle portions 153 can be manufactured using the same process. This makes it possible to provide a heat exchanger 110C that is easy to manufacture.

[0108] Furthermore, according to one example of the second modified example, the flow resistance of the heat medium in the three or more branch pipes 140 can be gradually increased from the branch pipes 140 farthest from the header openings 123A and 123B toward the branch pipes 140 closer to the header openings 123A and 123B. This makes it possible to make the flow rate of the heat medium uniform among the three or more branch pipes 140.

[0109] (Other Modifications of the Third Embodiment) In this embodiment, the first modification, and the second modification, the throttle sections 151-153 are formed by reducing the pipe diameter (outer diameter) of the branch pipe 140 in a portion of the extension direction of the branch pipe 140, but this is not limited to this. The throttle sections 151-153 may be formed by increasing the wall thickness of the branch pipe 140, which has a constant outer diameter, toward the radially inward direction of the branch pipe 140 in a portion of the extension direction of the branch pipe 140, thereby reducing the inner diameter. Furthermore, the throttle sections 151-153 may be, for example, so-called orifice members (orifice valves), which are plate members extending along a plane intersecting the extension direction of the branch pipe 140 and having a through hole formed therein. Furthermore, various valve mechanisms other than orifices may be used as the throttle sections 151-153. For example, by varying the valve opening degree between multiple branch pipes 140, the flow resistance of the heat medium in the multiple branch pipes 140 may gradually increase from the branch pipes 140 farther from the header opening 123A to the branch pipes 140 closer to the header opening 123A.

[0110] Furthermore, in this embodiment, this first modified example, and this second modified example, there is no limitation on the positions of the narrowed portions 151-153 in the extension direction of the branch pipe 140. Furthermore, in this embodiment, this first modified example, and this second modified example, the narrowed portions 151-153 are formed by drawing the pipe that forms each branch pipe 140, but this is not limited to this. A separate member provided with the narrowed portions 151-153 may be joined or incorporated into a part of the pipe that forms each branch pipe 140 in the extension direction.

[0111] Furthermore, in the present embodiment, the present first modification, and the present second modification, of the multiple branch pipes 140, the fourth branch pipe 140D, which is the farthest from the header opening 123A, is configured without the throttle portions 151 to 153, but this is not limiting, and the fourth branch pipe 140D may also be configured to include the throttle portions 151 to 153. In addition, it is also possible to appropriately combine the configuration shown in this embodiment, the configuration shown in the present modification 1, and the configuration shown in the present modification 2.

[0112] Although several embodiments of the present disclosure have been described above, these embodiments are presented as examples and are not intended to limit the scope of the disclosure. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the disclosure. These embodiments and their modifications are intended to be included within the scope and spirit of the disclosure, as well as within the scope of the present disclosure and its equivalents.

[0113] <Additional Notes> The heat exchangers 10A to 10E and 110A to 110C described in the respective embodiments can be understood, for example, as follows.

[0114] (1) Heat exchangers 10A to 10E according to a first aspect include headers 20A, 20B having header openings 23A, 23B through which a heat medium flows in or out and header flow paths 24A, 24B through which the heat medium flows, and headers 20A, 20B arranged at intervals in the direction in which the header flow paths 24A, 24B extend, with one end protruding into the header flow paths 24A, 24B and connected to the headers 20A, 20B so as to communicate with the header flow paths 24A, 24B, and three or more branch pipes 40 having the same pipe diameter, wherein the three or more branch pipes 40 are arranged so that the flow resistance of the heat medium between each of the three or more branch pipes 40 and the header flow paths 24A, 24B gradually increases from a branch pipe 40 farthest from the header openings 23A, 23B to a branch pipe 40 closer to the header openings 23A, 23B.

[0115] According to this aspect, in the heat exchangers 10A to 10E, the three or more branch pipes 40 connected to the headers 20A, 20B at intervals in the extension direction of the header flow paths 24A, 24B have a flow resistance for the heat medium between each of the branch pipes 40 and the header flow paths 24A, 24B that gradually decreases from the branch pipe 40 that is farthest from the header openings 23A, 23B to the branch pipe 40 that is closer to the header openings 23A, 23B. As a result, the flow resistance for the heat medium between the branch pipe 40 and the header flow paths 24A, 24B is greater for the branch pipe 40 that is closer to the header openings 23A, 23B than for the branch pipe 40 that is farther from the header openings 23A, 23B, and therefore the heat medium is less likely to flow from the header flow paths 24A, 24B into the branch pipe 40 or to flow from the branch pipe 40 into the header flow paths 24A, 24B. Conversely, the flow resistance of the heat medium between the branch pipe 40 and the header flow paths 24A, 24B is smaller for branch pipes 40 that are farther away from the header openings 23A, 23B than for branch pipes 40 that are closer to the header openings 23A, 23B. This makes it easier for the heat medium to flow from the header flow paths 24A, 24B into the branch pipe 40 or to flow from the branch pipe 40 to the header flow paths 24A, 24B. In this way, the flow rate of the heat medium can be made uniform among the multiple branch pipes 40. In this case, since three or more branch pipes 40 have the same pipe diameter, there is no need to prepare multiple types of branch pipes 40; simply connect multiple branch pipes 40 of the same type to the headers 20A, 20B. As a result, it is possible to provide heat exchangers 10A to 10E that are easy to manufacture.

[0116] (2) The heat exchangers 10A to 10C according to the second aspect are the heat exchangers 10A to 10C of (1), in which the three or more branch pipes 40 are arranged so that the protrusion lengths La, Lb into the header flow paths 24A, 24B gradually increase from the branch pipes 40 farthest from the header openings 23A, 23B toward the branch pipes 40 closest to the header openings 23A, 23B.

[0117] According to this aspect, by adjusting the projection lengths La, Lb into the header flow paths 24A, 24B, the flow resistance of the heat medium between each of the branch pipes 40 and the header flow paths 24A, 24B can be gradually increased from the branch pipes 40 farthest from the header openings 23A, 23B toward the branch pipes 40 closest to the header openings 23A, 23B. This makes it possible to provide heat exchangers 10A to 10C that are easy to manufacture.

[0118] (3) The heat exchangers 10A to 10C according to a third aspect are the heat exchangers 10A to 10C of (2), in which each of the three or more branch pipes 40 has an opening 42A that faces the direction in which the branch pipe 40 extends and communicates with the header flow paths 24A, 24B.

[0119] According to this aspect, in each of the three or more branch pipes 40, the heat transfer medium flows between each branch pipe 40 and the header flow paths 24A, 24B through the openings 42A that face in the direction in which the branch pipes 40 extend. As a result, the greater the protrusion lengths La, Lb of the branch pipes 40 into the header flow paths 24A, 24B, the smaller the distance between the openings 42A and the inner circumferential surfaces of the header bodies 21A, 21B over the entire opening 42A, making it more difficult for the heat transfer medium to flow over the entire opening 42A. This makes it easier to adjust the flow resistance of the heat transfer medium by adjusting the protrusion lengths La, Lb.

[0120] (4) A heat exchanger 10D, 10E according to a fourth aspect is a heat exchanger 10D, 10E according to any one of (1) to (3), in which the three or more branch pipes 40 are arranged such that the areas of the openings 45A, 45B communicating with the header flow paths 24A, 24B of the branch pipes 40 become gradually smaller from the branch pipe 40 farthest from the header openings 23A, 23B toward the branch pipe 40 closest to the header openings 23A, 23B.

[0121] According to this aspect, by adjusting the areas of the openings 45A, 45B that communicate with the header flow paths 24A, 24B, the flow resistance of the heat medium between each of the branch pipes 40 and the header flow paths 24A, 24B can be gradually increased from the branch pipes 40 that are farther away from the header openings 23A, 23B toward the branch pipes 40 that are closer to the header openings 23A, 23B. This makes it possible to provide heat exchangers 10D, 10E that are easy to manufacture.

[0122] (5) The heat exchangers 10D and 10E according to the fifth aspect are the heat exchangers 10D and 10E of (4), in which the three or more branch pipes 40 are arranged such that the opening dimension Xa in the longitudinal direction of the openings 45A and 45B gradually decreases from the branch pipe 40 farthest from the header openings 23A and 23B toward the branch pipe 40 closest to the header openings 23A and 23B.

[0123] According to this aspect, the areas of the openings 45A, 45B that communicate with the header flow paths 24A, 24B can be adjusted by adjusting the opening dimension Xa in the major axis direction. This makes it possible to provide the heat exchangers 10D, 10E that are easy to manufacture.

[0124] (6) The heat exchangers 10D and 10E according to a sixth aspect are the heat exchangers 10D and 10E of (4) or (5), wherein the openings 45A and 45B are formed on an inclined surface at the tip of each of the three or more branch pipes 40 that protrudes into the header flow paths 24A and 24B, the inclination angle of the inclined surface being inclined with respect to the direction in which the branch pipe 40 extends, and the three or more branch pipes 40 are arranged such that the inclination angle of the inclined surface with respect to the direction in which each branch pipe 40 extends gradually increases from the branch pipe 40 that is farther away from the header openings 23A and 23B toward the branch pipe 40 that is closer to the header openings 23A and 23B.

[0125] According to this aspect, the inclination angle of the inclined surface at the tip of the branch pipe 40 gradually increases from the branch pipe 40 farthest from the header openings 23A, 23B toward the branch pipe 40 closest to the header openings 23A, 23B. As a result, for three or more branch pipes 40 having the same pipe diameter, the area of ​​the openings 45A, 45B communicating with the header flow paths 24A, 24B of the branch pipe 40 can be gradually reduced from the branch pipe 40 farthest from the header openings 23A, 23B toward the branch pipe 40 closest to the header openings 23A, 23B. In this way, by using branch pipes 40 with the same internal pipe system but varying the inclination angle of the inclined surface, heat exchangers 10D, 10E can be provided in which the area of ​​the openings 45A, 45B communicating with the header flow paths 24A, 24B of the branch pipe 40 gradually decreases from the branch pipe 40 farthest from the header openings 23A, 23B toward the branch pipe 40 closest to the header openings 23A, 23B.

[0126] (7) The heat exchangers 10A to 10E according to a seventh aspect are the heat exchangers 10A to 10E according to any one of (1) to (6), in which the heat medium is a liquid. Examples of the liquid include water and antifreeze.

[0127] According to this aspect, when the heat medium is a liquid, the flow resistance of the heat medium between each of the branch pipes 40 and the header flow paths 24A, 24B gradually decreases from the branch pipes 40 farthest from the header openings 23A, 23B to the branch pipes 40 closest to the header openings 23A, 23B, thereby more effectively equalizing the flow rate of the heat medium among the multiple branch pipes 40.

[0128] (8) The heat exchanger 10C according to the eighth aspect is any one of the heat exchangers 10C described in (1) to (7), in which the three or more branch pipes 40 are connected to the headers 20A, 20B from different directions in the circumferential direction Dc around the axis along the direction in which the header flow paths 24A, 24B extend.

[0129] According to this aspect, three or more branch pipes 40 are connected to the headers 20A, 20B from different directions in the circumferential direction Dc about the axis of the header flow paths 24A, 24B, thereby making it possible to prevent the influence of a branch pipe 40 located upstream in the flow direction of the heat medium in the header flow paths 24A, 24B on the flow resistance from extending to other branch pipes 40 located downstream in the flow direction. This also makes it possible to more effectively equalize the flow rate of the heat medium among the multiple branch pipes 40.

[0130] (9) Heat exchangers 110A to 110C according to a ninth aspect each include a header having header openings 123A, 123B through which a heat medium flows in or out and header flow paths 124A, 124B through which the heat medium flows, and a plurality of branch pipes 140 having the same pipe diameter D, which are arranged at intervals in a direction in which the header flow paths 124A, 124B extend and are connected to the headers 120A, 120B so as to communicate with the header flow paths 124A, 124B. The plurality of branch pipes 140 have constriction sections 151 to 153 that constrict the cross-sectional area of ​​the flow path within the plurality of branch pipes 140, and the plurality of branch pipes 140 are arranged so that the flow resistance of the heat medium within the plurality of branch pipes 140 increases from the branch pipes 140 that are farther from the header openings 123A, 123B toward the branch pipes 140 that are closer to the header openings 123A, 123B.

[0131] According to this aspect, in heat exchangers 110A to 110C, the plurality of branch pipes 140 are provided with throttle sections 151 to 153, so that the flow resistance of the heat medium in the plurality of branch pipes 140 increases from the branch pipes 140 that are farther from header openings 123A, 123B toward the branch pipes 140 that are closer to header openings 123A, 123B. As a result, the flow resistance of the heat medium in the branch pipes 140 that are closer to header openings 123A, 123B is greater than that in the branch pipes 140 that are farther from header openings 123A, 123B, and therefore it becomes more difficult for the heat medium to flow from header flow paths 124A, 124B into the branch pipes 140. Conversely, the flow resistance of the heat medium in the branch pipes 140 that are farther from the header openings 123A and 123B is smaller than that in the branch pipes 140 that are closer to the header openings 123A and 123B, making it easier for the heat medium to flow from the header flow paths 124A and 124B into the branch pipes 140. In this way, the flow rate of the heat medium can be made uniform among the multiple branch pipes 140. In this case, since the multiple branch pipes 140 have the same pipe diameter D, there is no need to form holes in the headers 120A and 120B to connect branch pipes 140 with different pipe diameters, for example. This simplifies the structure of the headers 120A and 120B. As a result, it is possible to provide heat exchangers 110A to 110C that are easy to manufacture.

[0132] (10) A heat exchanger 110A according to a tenth aspect is the heat exchanger 110A of (9), wherein the branch pipes 140 away from the header openings 123A, 123B and the branch pipes 140 close to the header openings 123A, 123B each have the throttling portion 151, and the inner diameter d of the throttling portion 151 in the branch pipes 140 close to the header openings 123A, 123B is smaller than the inner diameter d of the throttling portion 151 in the branch pipes 140 away from the header openings 123A, 123B.

[0133] According to this aspect, the inner diameter d of the throttle portion 151 in the branch pipe 140 arranged closer to the header openings 123A, 123B is smaller than the inner diameter d of the throttle portion 151 in the branch pipe 140 arranged further from the header openings 123A, 123B. This makes it possible to increase the flow resistance of the heat medium in the multiple branch pipes 140 from the branch pipe 140 farther from the header openings 123A, 123B toward the branch pipe 140 closer to the header openings 123A, 123B, while using branch pipes 140 having the same pipe diameter D.

[0134] (11) The heat exchanger 110B according to the eleventh aspect is the heat exchanger 110B of (9) or (10), wherein the branch pipe 140 away from the header openings 123A, 123B and the branch pipe 140 close to the header openings 123A, 123B each have the throttling portion 152, and the length L of the throttling portion 152 in the branch pipe 140 close to the header openings 123A, 123B is greater than the length L of the throttling portion 152 in the branch pipe 140 away from the header openings 123A, 123B.

[0135] According to this aspect, the length L of the throttled portion 152 in the branch pipe 140 arranged closer to the header openings 123A, 123B is greater than the length L of the throttled portion 152 in the branch pipe 140 arranged further from the header openings 123A, 123B. This makes it possible to increase the flow resistance of the heat medium in the multiple branch pipes 140 from the branch pipe 140 farther from the header openings 123A, 123B toward the branch pipe 140 closer to the header openings 123A, 123B, while using branch pipes 140 having the same pipe diameter D.

[0136] (12) The heat exchanger 110B according to the twelfth aspect is the heat exchanger 110B of (11), in which the throttling portion 152 of the branch pipe 140 that is far from the header openings 123A, 123B and the throttling portion 152 of the branch pipe 140 that is close to the header openings 123A, 123B have the same inner diameter.

[0137] According to this aspect, the plurality of throttle portions 152 can be manufactured in the same process, making it possible to provide a heat exchanger 110B that is easy to manufacture.

[0138] (13) A heat exchanger 110C according to a thirteenth aspect is a heat exchanger 110C according to any one of (9) to (12), wherein the branch pipes 140 away from the header openings 123A, 123B and the branch pipes 140 close to the header openings 123A, 123B each have the throttling portions 153, and the number N of the throttling portions 153 in the branch pipes 140 close to the header openings 123A, 123B is greater than the number N of the throttling portions 153 in the branch pipes 140 away from the header openings 123A, 123B.

[0139] According to this aspect, the number N of throttle portions 153 in branch pipes 140 arranged closer to header openings 123A, 123B is made greater than the number N of throttle portions 153 in branch pipes 140 arranged further from header openings 123A, 123B. This makes it possible to increase the flow resistance of the heat medium in multiple branch pipes 140 from branch pipes 140 farther from header openings 123A, 123B toward branch pipes 140 closer to header openings 123A, 123B, while using branch pipes 140 having the same pipe diameter D.

[0140] (14) The heat exchanger 110C according to the fourteenth aspect is the heat exchanger 110C of (13), in which the throttling portion 153 of the branch pipe 140 that is far from the header openings 123A, 123B and the throttling portion 153 of the branch pipe 140 that is close to the header openings 123A, 123B have the same inner diameter.

[0141] According to this aspect, the plurality of throttle portions 153 can be manufactured in the same process, making it possible to provide a heat exchanger 110C that is easy to manufacture.

[0142] (15) The heat exchangers 110A to 110C according to the fifteenth aspect are any one of the heat exchangers 110A to 110C according to (9) to (14), wherein the plurality of branch pipes 140 include three or more branch pipes 140 arranged so that the flow resistance gradually increases from the branch pipe 140 that is farther away from the header openings 123A, 123B toward the branch pipe 140 that is closer to the header openings 123A, 123B.

[0143] According to this aspect, the flow resistance of the heat medium in the three or more branch pipes 140 can be gradually increased from the branch pipes 140 farthest from the header openings 123A, 123B toward the branch pipes 140 closer to the header openings 123A, 123B. Therefore, the flow rate of the heat medium can be made uniform among the three or more branch pipes 140.

[0144] According to the heat exchanger of the present disclosure, it is possible to provide a heat exchanger that is easy to manufacture.

[0145] DESCRIPTION OF SYMBOLS 10A to 10E...Heat exchanger 20A...Inlet header (header) 20B...Outlet header (header) 21A, 21B...Header body 22A, 22B...Bent pipe section 23A, 23B...Header opening 24A, 24B...Header flow path 40...Branch pipe 40A, 40P...First branch pipe 40B, 40Q...Second branch pipe 40C, 40R...Third branch pipe 40D, 40S...Fourth branch pipe 42A...Opening 45A, 45B...Opening 47A, 47B...Inclined surface 401a to 401d...One end 402a to 402d...Other end Dc...Circumferential direction Ga, Ga1a to Ga4...Gap La, La1 to La4, Lb, Lb1 to Lb4...Protrusion length Xa, Xa1 to Xa4...Opening dimension θa, θa1 to θa4, θb...inclination angle 110A to 110C...heat exchanger 120A...inlet side header 120B...outlet side header 121A...header body 121B...header body 122A, 122B...curved pipe section 123A, 123B...header opening 124A, 124B...header flow path 140...branch pipe 140A...first branch pipe 140B...second branch pipe 140C...third branch pipe 140D...fourth branch pipe 142A...opening 151, 151A to 151C, 152, 152A to 152C, 153, 153A to 153C...throttling section D...outer diameter (pipe diameter) d, d0, d1, d2, d3, d11, d12...inner diameter L, L1 to L3...length

Claims

1. A heat exchanger comprising: a header having a header opening through which a heat medium flows in or out, and a header flow path through which the heat medium flows; and three or more branch pipes having the same pipe diameter, spaced apart in the direction in which the header flow path extends, one end of which protrudes into the header flow path and is connected to the header so as to communicate with the header flow path, wherein the three or more branch pipes are arranged such that the flow resistance of the heat medium between each of the three or more branch pipes and the header flow path gradually increases from a branch pipe among the three or more branch pipes that is farther from the header opening to a branch pipe among the three or more branch pipes that is closer to the header opening.

2. A heat exchanger as described in claim 1, wherein the three or more branch pipes are arranged so that the length of protrusion into the header flow path gradually increases from the branch pipe farthest from the header opening to the branch pipe closer to the header opening.

3. The heat exchanger according to claim 2, wherein each of the three or more branch pipes has an opening that faces the direction in which the branch pipe extends and communicates with the header flow path.

4. A heat exchanger as described in claim 1 or 2, wherein the three or more branch pipes are arranged such that the area of ​​the openings of the branch pipes communicating with the header flow passage gradually decreases from the branch pipe farther from the header opening to the branch pipe closer to the header opening.

5. A heat exchanger as described in claim 4, wherein the three or more branch pipes are arranged such that the opening dimensions in the major axis direction of the openings gradually decrease from the branch pipe farthest from the header opening to the branch pipe close to the header opening.

6. A heat exchanger as described in claim 4, wherein each of the three or more branch pipes has an opening formed on an inclined surface that is inclined with respect to the direction in which the branch pipe extends at a tip of the branch pipe that protrudes into the header flow path, and the three or more branch pipes are arranged such that the inclination angle of the inclined surface with respect to the direction in which each branch pipe extends gradually increases from the branch pipe away from the header opening to the branch pipe closer to the header opening.

7. The heat exchanger according to any one of claims 1 to 3, wherein the heat medium is a liquid.

8. A heat exchanger as claimed in any one of claims 1 to 3, wherein the three or more branch pipes are connected to the header from different directions in a circumferential direction about an axis along the direction in which the header flow path extends.

9. A heat exchanger comprising: a header having a header opening through which a heat medium flows in or out, and a header flow path through which the heat medium flows; and a plurality of branch pipes having the same pipe diameter, arranged at intervals in the direction in which the header flow path extends, connected to the header so as to communicate with the header flow path, wherein the plurality of branch pipes have constriction portions which constrict the cross-sectional area of ​​the flow path in the plurality of branch pipes, and the plurality of branch pipes are arranged such that the flow resistance of the heat medium in the plurality of branch pipes increases from a branch pipe among the plurality of branch pipes that is farther from the header opening toward a branch pipe among the plurality of branch pipes that is closer to the header opening.

10. A heat exchanger as described in claim 9, wherein the branch pipe away from the header opening and the branch pipe close to the header opening each have the throttle portion, and the inner diameter of the throttle portion in the branch pipe close to the header opening is smaller than the inner diameter of the throttle portion in the branch pipe away from the header opening.

11. A heat exchanger as described in claim 9, wherein the branch pipe away from the header opening and the branch pipe close to the header opening each have the throttle portion, and the length of the throttle portion in the branch pipe close to the header opening is greater than the length of the throttle portion in the branch pipe away from the header opening.

12. The heat exchanger according to claim 11, wherein the throttle portion of the branch pipe remote from the header opening and the throttle portion of the branch pipe close to the header opening have the same inner diameter.

13. A heat exchanger as described in claim 9, wherein the branch pipe away from the header opening and the branch pipe close to the header opening each have the throttle portion, and the number of the throttle portions in the branch pipe close to the header opening is greater than the number of the throttle portions in the branch pipe away from the header opening.

14. The heat exchanger according to claim 13, wherein the throttle portion of the branch pipe remote from the header opening and the throttle portion of the branch pipe close to the header opening have the same inner diameter.

15. A heat exchanger as described in any one of claims 9 to 14, wherein the plurality of branch pipes include three or more branch pipes arranged so that the flow resistance gradually increases from the branch pipe away from the header opening to the branch pipe closer to the header opening.

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