JP2013088092A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger capable of improving heat exchange efficiency by expanding the contact area between an inner pipe 11 and a fin 13.SOLUTION: A double pipe heat exchanger (inner heat exchanger) 10 that exchanges heat between a first fluid and a second fluid while an inner pipe 11 in which the first fluid flows is inserted into an outer pipe 12 in which the second fluid (high-pressure refrigerant) flows and fins 13 are interposed between the inner pipe 11 and outer pipe 12, includes an end cap 14 having a first opening 15 to which a lengthwise end 12b of the outer pipe 12 is connected and into which the inner pipe 11 and fin 13 are inserted, a second opening 16 which is opened on the same straight line with the first opening 15 and into which only the inner pipe 11 is inserted, and a third opening 17 which communicates with a gap between the inner pipe 11 and the outer pipe 12 and in which the second fluid (high-pressure refrigerant) flows, a lengthwise end 13b of the fin 13 being extended up to a position facing the third opening 17.

Description

  The present invention relates to a double-tube heat exchanger that inserts an inner tube into an outer tube and arranges fins between the inner tube and the outer tube to perform heat exchange.

  Conventionally, an inner tube, an outer tube into which the inner tube is inserted, a fin interposed between the two tubes, and an end of the outer tube, the inner tube penetrates and the inner tube and the outer tube 2. Description of the Related Art A double-tube heat exchanger having an end cap having a communication channel communicating with a gap is known (for example, see Patent Document 1 and Patent Document 2).

JP 2010-96225 A JP 2006-3071 A

  However, in the conventional heat exchanger, only the inner tube is inserted into the end cap, and the outer tube and the fin are inserted only up to the inlet opening of the end cap. Therefore, the contact area between the inner tube and the fin is limited, and the heat exchange efficiency is low.

  Therefore, an object of the present invention is to provide a heat exchanger that can increase the contact area between the inner tube and the fins and improve the heat exchange efficiency.

  In order to achieve the above object, according to the present invention, an inner tube through which a first fluid flows is inserted into an outer tube through which a second fluid flows, and a fin is interposed between the inner tube and the outer tube. In a double-tube heat exchanger that exchanges heat between a fluid and the second fluid, a longitudinal opening of the outer tube is connected, and a first opening through which the inner tube and the fin are inserted A second opening that opens in the same straight line as the first opening and through which only the inner tube passes, and a third opening through which the second fluid flows in communication with the gap between the inner tube and the outer tube The fin has an end cap that extends to a position where the end in the longitudinal direction faces the third opening.

According to this invention, the end cap provided at the longitudinal direction end of the outer tube has the first opening through which the inner tube and the fin are inserted, and the inner tube opens only in the same straight line as the first opening. And a third opening through which the second fluid flows in communication with the gap between the inner tube and the outer tube. As a result, the inner tube and the fin are inserted into the end pipe, and the contact area between the inner tube and the fin can be increased.
In addition, by extending the end of the fin in the longitudinal direction to the position facing the third opening, the third opening is blocked by the fin while increasing the contact area between the inner tube and the fin. Preventing the flow of the second fluid. As a result, the contact area between the inner tube and the fins can be increased, and the heat exchange efficiency can be improved.

It is a whole system figure which shows the refrigerating cycle which applied the heat exchanger of Example 1 as an internal heat exchanger. It is a disassembled perspective view which shows the internal heat exchanger of Example 1. FIG. It is AA sectional drawing in FIG. It is a principal part expansion perspective view which shows the longitudinal direction edge part of a fin. It is a longitudinal cross-sectional view in the longitudinal direction edge part of the internal heat exchanger of Example 1. FIG. It is explanatory drawing which shows the manufacturing method of the internal heat exchanger in Example 1, (a) shows an inner pipe formation process, (b) shows an outer pipe formation process, (c) shows a fin formation process. It is explanatory drawing which shows the manufacturing method of the internal heat exchanger in Example 1, (d) shows a pipe | tube assembly process, (e) shows an end cap assembly | attachment process, (f) shows a ball threading process, (g) A brazing process is shown. It is a figure which shows the heat exchanger of a comparative example, (a) shows the principal part expanded sectional view, (b) is a perspective view which shows an end cap. It is a longitudinal cross-sectional view of the longitudinal direction edge part in the other example of the heat exchanger of this invention.

  Hereinafter, the best mode for realizing the heat exchanger of the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing a refrigeration cycle in which the heat exchanger of Example 1 is applied as an internal heat exchanger. FIG. 2 is an exploded perspective view illustrating the internal heat exchanger according to the first embodiment. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is an enlarged perspective view of a main part showing an end portion in the longitudinal direction of the fin. FIG. 5 is a vertical cross-sectional view at the end in the longitudinal direction of the internal heat exchanger of the first embodiment.

  As shown in FIG. 1, the refrigeration cycle in the first embodiment includes a compressor 1, a condenser (gas cooler) 2, an expansion valve 3, and an evaporator 4 that are sequentially connected in an annular manner, and a high-pressure refrigerant discharged from the condenser 2 And an internal heat exchanger (heat exchanger) 10 for exchanging heat between the refrigerant and the low-pressure refrigerant exiting the evaporator 4.

  The compressor 1 is driven by an engine, a motor, or the like, and compresses the gas refrigerant from the evaporator 4 to obtain a high-temperature / high-pressure gas refrigerant.

  The condenser 2 is a condenser that exchanges heat between the high-temperature and high-pressure gas refrigerant from the compressor 1 and the outside air to form a low-temperature and high-pressure gas refrigerant. The condenser 2 includes a pair of left and right header tanks arranged in parallel and spaced apart from each other, a heat exchange tube arranged in a large number in horizontal parallel with both ends communicating with the header tank, and adjacent heat exchanger tubes. And a fin disposed in the air circulation gap of the exchange tube. Then, the interior of the pair of header tanks is partitioned in the lateral direction by the partitioning means, so that at least two refrigerant passages by the heat exchange tubes are provided, such as an inlet side passage group, an intermediate passage group, and an outlet side passage group. It is divided into passage groups.

  The expansion valve 3 is installed in the engine room, and the pressure of the high-pressure gas refrigerant from the condenser 2 is a low-pressure liquid-gas mixed refrigerant. In the case of the first embodiment, a control type expansion valve that controls the opening degree of the expansion valve so as to keep the superheat degree of the refrigerant constant (superheat) based on the outlet refrigerant temperature and the outlet refrigerant pressure of the condenser 2 is adopted. Yes.

  The evaporator 4 is a heat exchanger that is disposed together with a blower or the like in a vehicle air conditioning unit that performs vehicle interior air conditioning. By circulating the low-temperature and low-pressure liquid-gas mixed refrigerant from the expansion valve 3, heat is taken from the surrounding air, the temperature of the refrigerant is increased, and gasification is promoted. For this reason, the evaporator 4 has a structure in which the core, piping, and flange are integrated, thereby preventing refrigerant leakage into the vehicle compartment including slow leaks such as O-ring seals.

  The internal heat exchanger 10 exchanges heat by allowing the high-pressure refrigerant exiting the condenser 2 and the low-pressure refrigerant exiting the evaporator 4 to flow adjacent to each other. That is, since heat is exchanged in the refrigeration cycle and heat is not exchanged with the external air, it is called an “internal heat exchanger”. The internal heat exchanger 10 reduces the refrigerant temperature at the inlet of the expansion valve 3 and lowers the inlet enthalpy of the evaporator 4, thereby improving COP (Coefficient Of Performance). The internal heat exchanger 10 includes an inner tube 11, an outer tube 12, fins 13, and an end cap 14.

  The inner pipe 11 is an aluminum round pipe, and the low-pressure refrigerant (first fluid) exiting the evaporator 4 flows inside. An Al—Si alloy (for example, JIS A4343 or JIS A4045) as a brazing material is attached to the outer peripheral surface 11 a of the inner tube 11.

  The outer tube 12 is an aluminum round tube having an inner diameter size into which the inner tube 11 can be inserted with a gap therebetween, and a high-pressure refrigerant (secondary) that has come out of the capacitor 2 between the inner tube 11 inserted inside. Fluid) flows. Here, the inner tube 11 and the outer tube 12 form a so-called double tube structure arranged on a concentric axis. Further, an Al—Si alloy (for example, JIS A4343 or JIS A4045) as a brazing material adheres to the inner peripheral surface 12 a of the outer tube 12.

The fins 13 are aluminum tubes having a large number of projections and depressions 13a,... Arranged in the circumferential direction of the inner tube 11 and the outer tube 12 and extending in the longitudinal direction. Is intervened. That is, the fin 13 is disposed in a flow path through which the high-pressure refrigerant (second fluid) that has exited the condenser 2 flows, and the low-pressure refrigerant flows between a large number of irregularities 13a. And as shown in FIG. 3, as for many unevenness | corrugations 13a, ... of the fin 13, the radial direction front-end | tip part contacts the outer peripheral surface 11a of the inner tube 11, or the inner peripheral surface 12a of the outer tube | pipe 12. As shown in FIG.
Further, as shown in FIG. 4, the fin 13 of the internal heat exchanger 10 according to the first embodiment has a communication hole (communication means) 13c that communicates between a large number of irregularities 13a in the vicinity of the longitudinal end portion 13b. ... is formed. The communication hole 13 c is an opening provided on a surface of the unevenness 13 a that stands between the inner tube 11 and the outer tube 12.

  And in the internal heat exchanger 10 of Example 1, the longitudinal direction dimension of the outer tube 12 is set to the shortest length among the inner tube 11, the outer tube 12, and the fin 13, and the longitudinal direction dimension of the inner tube 11 is The longest length is set. Therefore, in a state where the inner tube 11 is inserted into the outer tube 12 and the fins 13 are interposed therebetween, as shown in FIG. 2, the longitudinal ends 13 b of the fins 13 are outward (outer tube 12). The longitudinal end portion 11b of the inner tube 11 projects outwardly from the fin 13 (longitudinal direction of the fin 13).

  The end cap 14 is provided at the longitudinal end 12 b of the outer tube 12 and branches the flow direction of the high-pressure refrigerant exiting the condenser 2 flowing on the same axis and the low-pressure refrigerant exiting the evaporator 4. The end cap 14 has a first opening 15, a second opening 16, and a third opening 17.

  The first opening 15 is set to an inner diameter through which the inner tube 11 and the fin 13 can be inserted, and the inner tube 11 protruding from the outer tube 12 and the longitudinal end portion 13b of the fin 13 are inserted. The longitudinal end portion 12 b of the outer tube 12 abuts on the peripheral edge portion 15 a of the first opening portion 15.

  The second opening portion 16 is set to have an inner diameter through which only the inner tube 11 can be inserted, and a longitudinal end portion 11 b of the inner tube 11 protruding from the fin 13 passes therethrough. Here, the first opening 15 and the second opening 16 are open in the coaxial direction.

  The third opening 17 communicates with the gap between the inner tube 11 and the outer tube 12, and the high-pressure refrigerant (second fluid) that has exited the condenser 2 flows through the third opening 17. Here, the third opening 17 is open in a direction orthogonal to the opening direction of the first and second openings 15 and 16. The longitudinal end portion 13 b of the fin 13 inserted into the end cap 14 from the first opening portion 15 extends to a position facing the third opening portion 17.

  Next, the manufacturing method of the internal heat exchanger 10 of Example 1 is demonstrated.

  6A is an explanatory view showing a method for manufacturing an internal heat exchanger in Example 1, wherein (a) shows an inner tube forming step, (b) shows an outer tube forming step, and (c) shows fin formation. A process is shown. FIG. 6B is an explanatory view showing a method of manufacturing the internal heat exchanger in Example 1, (d) shows a tube assembly process, (e) shows an end cap assembly process, and (f) shows a ball threading process. The process is shown, and (g) a brazing process is shown.

  In the inner tube forming step, as shown in FIG. 6A (a), the aluminum flat steel plate is roll-formed with the surface to which the brazing material is attached facing outward, the mating portions are welded, and the brazing material is adhered to the outer peripheral surface 11a. The attached inner tube 11 is formed. Here, the outer diameter of the inner tube 11 is set to 15 mm, for example.

  In the outer tube forming step, as shown in FIG. 6A (b), the aluminum flat steel plate is roll-formed with the surface to which the brazing material is attached facing inside, and the mating portions are welded to the inner circumferential surface 12a. The outer tube 12 to which is attached is formed. Here, the inner diameter of the outer tube 12 is set to 19.6 mm, for example.

  In the fin forming step, as shown in FIG. 6A (c), an aluminum flat steel plate is pressed to form a large number of irregularities 13a on the entire surface, and then roll-formed to weld the mating portions. Thereby, the tubular fin 13 which has many unevenness | corrugations 13a, ... along the circumferential direction and extended in a longitudinal direction is formed. Here, the height of the unevenness 13a is set to 1.8 mm, for example, and the pitch interval in the circumferential direction is set to 1.4 mm, for example.

In the tube assembly step, as shown in FIG. 6B (d), the inner tube 11 formed in the inner tube forming step is inserted into the outer tube 12 formed in the outer tube forming step. The fins 13 formed in the fin forming step are inserted between the tubes 12. At this time, the longitudinal end portion 13b of the fin 13 protrudes outward from the outer tube 12 (longitudinal direction of the outer tube 12), and the longitudinal end portion 11b of the inner tube 11 extends outward from the fin 13 (longitudinal direction of the fin 13). Protruding in the direction).
When the outer diameter of the inner tube 11 is set to 15 mm and the inner diameter of the outer tube 12 is set to 19.6 mm, the gap between the inner tube 11 and the outer tube 12 is 2.3 mm. For this reason, if the height of the unevenness 13 a of the fin 13 is set to 1.8 mm, the fin 13 can be smoothly inserted between the inner tube 11 and the outer tube 12.

  In the end cap assembling step, as shown in FIG. 6B (e), end caps 14 are attached to both ends of the outer tube 12. At this time, the inner tube 11 and the fins 13 protruding from the outer tube 12 are inserted into the first opening 15 of the end cap 14. The longitudinal end 11 b of the inner tube 11 protrudes from the second opening 16, and the longitudinal end 13 b of the fin 13 faces the third opening 17.

  In the ball passing process, as shown in FIG. 6B (f), the metal ball B is inserted into the inner tube 11 to which the end cap 14 has been assembled by the end cap assembling process from one longitudinal end 11b. Let it penetrate as it is. The metal ball B has an outer diameter larger than the inner diameter of the inner tube 11. Thereby, the inner tube 11 is pushed and expanded from the inside together with the fins 13 to increase the diameter. Therefore, the outer peripheral surface 11a of the inner tube 11 is in close contact with the radial tip portion of the unevenness 13a of the fin 13 and the second opening 16 of the end cap 14, and the radial tip portion of the unevenness 13a of the fin 13 is The tube 12 is in close contact with the inner peripheral surface 12 a of the tube 12 and the first opening 15 of the end cap 14. The outer diameter of the metal ball B is set so that the outer diameter of the inner tube 11 is the same as that of the second opening 16.

  In the brazing step, as shown in FIG. 6B (g), the entire assembly in a state where the contact portions of the inner tube 11, the outer tube 12, the fins 13 and the end cap 14 are in close contact with each other by the ball passing step is heated. The brazing material adhering to the inner tube 11 and the outer tube 12 is melted. Thereby, the inner tube 11 and the outer tube 12 are respectively integrated with the fin 13 and the end cap 14 is fixed. Finally, the branch pipe 19 is attached to the inner pipe 11 and the end cap 14, and the double pipe type internal heat exchanger 10 is formed.

Next, the operation will be described.
First, “end cap in heat exchanger of comparative example” will be described, and then “fin extension action” in the heat exchanger of example 1 will be described.

[End cap in heat exchanger of comparative example]
FIG. 7 is a view showing a heat exchanger of a comparative example, (a) is an enlarged cross-sectional view of the main part, and (b) is a perspective view showing an end cap.

  The heat exchanger 20 of the comparative example includes an inner tube 21 through which a low-temperature and low-pressure refrigerant flows, an outer tube 22 into which an inner tube 21 is inserted, and a high-temperature and high-pressure refrigerant through the gap between the inner tube 21, and the inner tube 21 and the outer tube. A fin 23 interposed between the end tube 24 and an end cap 24 provided at an end of the outer tube 22.

  Here, the inner tube 21 is set longer in the longitudinal direction than the outer tube 22, and the longitudinal end 21 b of the inner tube 21 protrudes from the longitudinal end 12 b of the outer tube 22. The end cap 24 includes a first opening 24a through which the inner tube 21 is inserted, a second opening 24b through which the inner tube 21 passes through the first opening 24a, and the inner tube 21. And a third opening 24c through which a high-temperature and high-pressure refrigerant flows in communication with the gap between the outer tube 22 and the outer tube 22.

  Further, an annular spigot portion 25 inserted into the outer tube 22 is formed around the first opening 24a of the end cap 24, as shown in FIG. 7B. The inlay portion 25 is inserted between the inner tube 21 and the outer tube 22 and prevents rattling of the end cap 24 and refrigerant leakage. Note that the outer surface 25 a of the spigot portion 25 is in contact with the inner peripheral surface 22 a of the outer tube 22, and a gap is generated between the inner peripheral surface 25 b of the spigot portion 25 and the inner tube 21. For this reason, the high-temperature / high-pressure refrigerant flowing between the inner tube 21 and the outer tube 22 flows between the spigot portion 25 and the inner tube 21 and flows out from the third opening 24c.

  Further, the insertion portion 25 is inserted into the outer tube 22, whereby the longitudinal end portion 23 b of the fin 23 interposed between the inner tube 21 and the outer tube 22 interferes with the insertion portion 25. For this reason, the position of the longitudinal direction edge part 23b of the fin 23 is controlled, and it cannot extend any more. As a result, the contact area between the inner tube 21 and the fins 23 is limited, and the heat exchange efficiency is kept low.

[Fin extension action]
In the internal heat exchanger 10 of the first embodiment, the inner diameter of the first opening 15 of the end cap 14 is set to a size that allows the inner tube 11 and the fin 13 to be inserted. The longitudinal end 13 b of the fin 13 that has entered the end cap 14 from the first opening 15 extends to a position facing the third opening 17 of the end cap 14. Thus, the inner tube 11 and the fin are compared with the heat exchanger 20 of the comparative example in which the fin 23 interferes with the spigot portion 25 inside the outer tube 22 and the position of the longitudinal end portion 23b of the fin 23 is restricted. The contact area with 13 can be expanded and the heat exchange efficiency can be improved.

  Further, in the internal heat exchanger 10 of the first embodiment, since the spigot portion is not inserted into the outer tube 12, the flow path of the high-pressure refrigerant flowing between the inner tube 11 and the outer tube 12 is not narrowed. It does not hinder the flow of refrigerant. Therefore, it is possible to further prevent the heat exchange efficiency from decreasing.

  Furthermore, in the internal heat exchanger 10 of the first embodiment, in order to make the flow of the high-pressure refrigerant smooth, the unevenness 13a,... Of the fins 13 is aligned along the circumferential direction of the inner tube 11 and the outer tube 12, and is elongated. Extends in the direction. On the other hand, in the longitudinal end portion 13b of the fin 13 facing the third opening 17, communication holes 13c,. Therefore, even the high-pressure refrigerant that flows through the portion that does not face the third opening 17 can flow smoothly toward the third opening 17 and can prevent a decrease in heat exchange efficiency.

Next, the effect will be described.
In the heat exchanger of Example 1, the effects listed below can be obtained.

(1) The inner pipe 11 through which the first fluid (low-pressure refrigerant) flows is inserted into the outer pipe 12 through which the second fluid (high-pressure refrigerant) flows, and the fins 13 are interposed between the inner pipe 11 and the outer pipe 12. In a double-pipe heat exchanger (internal heat exchanger) 10 that exchanges heat between the first fluid (low pressure refrigerant) and the second fluid (high pressure refrigerant). The longitudinal direction end 12b of the outer tube 12 is connected, the first opening 15 through which the inner tube 11 and the fin 13 are inserted, and the first opening 15 are opened in the same straight line, and only the inner tube 11 is opened. An end cap 14 having a second opening 16 through which the second fluid (high-pressure refrigerant) flows and communicates with a gap between the inner tube 11 and the outer tube 12. The fin 13 extends to a position where the longitudinal end 13b faces the third opening 17. It was.
Thereby, the contact area of the inner pipe 11 and the fin 13 can be expanded, and the improvement of heat exchange efficiency can be aimed at.

(2) The fin 13 has a large number of projections and depressions 13a,... Extending along the circumferential direction of the inner tube 11 and the outer tube 12 and extending in the longitudinal direction. In the vicinity, communication means (communication holes) 13c,... For communicating between the plurality of irregularities 13a,.
Thereby, even the high-pressure refrigerant that flows through the portion that does not face the third opening 17 can flow smoothly toward the third opening 17, thereby preventing a decrease in heat exchange efficiency.

  As mentioned above, although the heat exchanger of this invention has been demonstrated based on Example 1, about a concrete structure, it is not restricted to this Example, The summary of the invention which concerns on each claim of a claim Unless it deviates, design changes and additions are allowed.

  In the heat exchanger according to the first embodiment, the longitudinal end 12 b of the outer tube 12 and the peripheral edge 15 a of the first opening 15 of the end cap 14 are abutted, and the fin 13 is inserted into the first opening 15. This prevents the end cap 14 from being displaced.

  However, for example, as shown in FIG. 8, the end cap 14 is provided with an inlay portion 18 that protrudes from the peripheral edge portion of the first opening 15 and is inserted into the outer tube 12, and the longitudinal end portion of the outer tube 12. The inner diameter of 12b may be expanded to a size that allows the spigot 18 to be fitted. Thereby, since the inner peripheral surface 12a of the outer pipe 12 and the outer peripheral surface 18a of the spigot part 18 are overlapped and adhered, the airtightness is improved, and the refrigerant leakage preventing force can be further enhanced.

  In the first embodiment, the communication holes 13c,... Are formed in the fins 13 as the communication means, but the present invention is not limited to this. Since it is only necessary to communicate between a large number of irregularities 13a,..., For example, the inner diameter of the end cap 14 at a position facing the longitudinal end portion 13b of the fin 13 is enlarged, and a gap is formed between the fin 13 and the end cap 14. By providing, you may communicate between the unevenness | corrugation 13a. Moreover, the height of the unevenness 13a,... May be set low only in the vicinity of the longitudinal end portion 13b of the fin 13 so that a gap is formed between the end cap 14 and the end cap 14.

  Moreover, in Example 1, although the example of the internal heat exchanger in the refrigerating cycle applied to the air conditioner system of a vehicle was shown, in the refrigerating cycle other than a vehicle, for example, an air conditioner system for homes, an air conditioner system of a factory, a business office, etc. It can also be applied as an internal heat exchanger. In short, the present invention can be applied to any heat exchanger having a double tube structure having an inner tube and an outer tube, fins interposed therebetween, and end caps provided at both ends.

10 Internal heat exchanger (heat exchanger)
11 Inner tube 11a Outer peripheral surface 11b Longitudinal end 12 Outer tube 12a Inner peripheral surface 12b Longitudinal end 13 Fin 13a Concavity and convexity 13b Longitudinal end 13c Communication hole (communication means)
14 End cap 15 1st opening part 15a Peripheral part 16 2nd opening part 17 3rd opening part 18 Inlay part

Claims (3)

An inner tube through which the first fluid flows is inserted into an outer tube through which the second fluid flows, and a fin is interposed between the inner tube and the outer tube to heat between the first fluid and the second fluid. In the double-pipe heat exchanger that performs exchange,
A longitudinal opening of the outer tube is connected, a first opening through which the inner tube and the fin are inserted, and a second opening through which only the inner tube is inserted and opened in the same straight line as the first opening. And an end cap having a third opening through which the second fluid flows in communication with a gap between the inner tube and the outer tube,
The fin has a longitudinal end extending to a position facing the third opening. The heat exchanger according to claim 1, wherein
The fins are arranged along the circumferential direction of the inner tube and the outer tube, and have a number of irregularities extending in the longitudinal direction,
A heat exchanger characterized in that communication means for communicating between the plurality of irregularities is provided in the vicinity of the end in the longitudinal direction of the fin. In the heat exchanger according to claim 1 or claim 2,
The end cap protrudes from the periphery of the first opening, and has an inlay portion that is inserted into the outer tube,
An end portion opening of the outer tube is set to an inner diameter dimension capable of fitting the inlay portion.