JP2019190764A - Heat exchanger - Google Patents

Abstract

To provide a heat exchanger that reduces a difference in rate of temperature rise between a tube and a binding member which may cause heat strain.SOLUTION: A plurality of corrugated fins 12 laminated alternately with a plurality of flat tubes 11 is formed with a short pitch part 19 with a fin pitch which is shorter than the other parts in an end upstream of a cooling water flow in the vicinity of a header tank 16 on an inflow side of cooling water.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat exchanger.

  2. Description of the Related Art Conventionally, a heat exchanger including a core having a structure in which tubes and fins are alternately stacked and two header tanks to which both ends of these tubes are fixed is known. In such a heat exchanger, an example in which both ends of a protective member for protecting the core are fixed to these header tanks is also known. In this example, the protection member corresponds to a restraining member that restrains the two header tanks.

  Here, thermal distortion that may occur in the heat exchanger will be described by taking a heater core for a vehicle that is one form of the heat exchanger as an example. When the heat exchanger is a heater core, heat exchange is performed between the engine coolant flowing in the tube and the air-conditioning air flowing in contact with the outer surface of the tube and the fins.

  2. Description of the Related Art In recent years, vehicles having a configuration in which an engine is temporarily stopped at the time of a pause such as waiting for a signal, that is, a so-called idling stop vehicle has become widespread. In this type of vehicle, the circulation of the cooling water to the heater core is usually stopped as the engine is stopped. In such a case, the cooling water flowing through the heater core is frequently interrupted as the engine is started and stopped.

  When the cooling water heated by the engine begins to flow into the tube at the repeated cooling water disconnection, the temperature of the tube rapidly increases when the cooling water heated by the engine begins to flow into the tube. . At this time, since the cooling member does not circulate through the inside of the protective member and does not come into contact with the cooling water on the surface, the temperature rise is slower than that of the tube. As a result, there is a discrepancy between the expansion amount of the protective member that restrains the two header tanks and the expansion amount of the tube, and thermal distortion occurs in the tube.

  Therefore, thermal distortion frequently occurs because the cooling water flowing through the heater core is repeatedly interrupted as the engine is started and stopped. This can lead to tube degradation. On the other hand, it has been proposed to reduce the thermal distortion by relaxing the restraining force of the protective member (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2006-90116

  However, the conventional technique disclosed in Patent Document 1 is a technique for reducing the thermal strain of the tube when a large difference occurs in the expansion amount between the tube and the protection member, and the expansion amount between the tube and the protection member. It does not suppress the fact that there is a big difference.

  The restraining member that restrains the two header tanks and has a temperature rise rate slower than that of the tube at the start of inflow of the cooling water into the tube is not limited to the protective member.

  An object of this invention is to provide the heat exchanger which reduces the difference of the temperature rise rate of the tube which causes a thermal distortion, and a restraint member in view of the said point.

The invention described in claim 1 for achieving the above object is a heat exchanger for exchanging heat between the heat transfer fluid and air, wherein the heat transfer fluid flows in from the outside of the heat exchanger. 16, 41, 61), an inflow tube (11, 21, 31, 51, 71) that is fixed to the first tank and into which the heat transfer fluid flows directly from the first tank, and is fixed to the inflow tube A second tank (17, 42, 62) into which the heat transfer fluid flows directly from the inflow tube;
The heat transfer fluid does not flow directly from the first tank and is fixed to the first tank and the second tank so as to restrain the first tank and the second tank (15, 52). 72), and the tube closer to the first tank than the tube central portion (11c, 21c, 31c, 51c, 71c) equidistant from both ends of the inflow tube along the extending direction of the inflow tube The upstream portion (11u, 21u, 31u, 51u, 71u), and the tube downstream portion (11d, 21d, 31d, 51d, 71d), an upstream capacity comprising an upstream adjacent member (12u, 55u, 75u) in contact with the tube upstream portion and the tube upstream portion The heat capacity of the forming section (Xu) is larger than the heat capacity of the downstream capacity forming section (Xd) composed of the downstream adjacent members (12d, 55d, 75d) in contact with the tube downstream section and the tube downstream section, It is a vessel.

  Thus, since the heat capacity of the upstream capacity forming portion is larger than the heat capacity of the downstream capacity forming portion, when the heated heat medium fluid starts to flow into the inflow tube, it is upstream from the heat medium fluid in the upstream portion of the tube. A relatively large amount of heat is lost to the side capacitance forming portion. As a result, the difference between the temperature increase rate of the tube upstream portion and the tube downstream portion and the temperature increase rate of the restraining member when the heated heat transfer fluid starts to flow into the inflow tube is suppressed. Therefore, the thermal distortion of the inflow tube is reduced.

  Reference numerals in parentheses attached to each component and the like indicate an example of a correspondence relationship between the component and the like and specific components described in the embodiments described later.

It is explanatory drawing of the usage condition of the heat exchanger of 1st Embodiment. It is a partial enlarged view of the heat exchanger of 1st Embodiment. It is a fragmentary sectional view of the heat exchanger of a 2nd embodiment. It is a fragmentary sectional view of the heat exchanger of a 3rd embodiment. It is a perspective view of the heat exchanger of 4th Embodiment. It is a front view of the heat exchanger of 4th Embodiment. It is a partial enlarged view of the heat exchanger of 4th Embodiment. It is a front view of the heat exchanger of 5th Embodiment. It is a partial enlarged view of the heat exchanger of 5th Embodiment. It is XX sectional drawing of the heat exchanger of 5th Embodiment. It is a partial enlarged view of the XI-XI cross section of the heat exchanger of 5th Embodiment. It is a partial enlarged view of the XII-XII cross section of the heat exchanger of 5th Embodiment.

  Hereinafter, a plurality of embodiments will be described. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
As shown in FIG. 1, the heat exchanger 10 according to the first embodiment of the present invention is connected to an engine 1 of a vehicle, and is heated with cooling water (corresponding to a heat transfer fluid) heated by the heat of the engine 1. Used for heat exchange with industrial air. Air-conditioning air is air that is blown out from the vehicle air-conditioner into the vehicle cabin.

  The heat exchanger 10 includes a core 14 having a structure in which a plurality of flat tubes 11 and a plurality of corrugated fins 12 are alternately stacked one by one, and protective members 15 are disposed at both ends in the stacking direction. ing. Hereinafter, the stacking direction of the flat tubes 11 is simply referred to as a stacking direction.

  Each flat tube 11 is a tubular member in which a flow path through which cooling water flows is formed. Each flat tube 11 has a flat shape, and a cross-sectional shape perpendicular to the extending direction (that is, the longitudinal direction) in which the flat tube 11 extends is a rounded rectangular shape. The extending direction of the flat tube 11 and the stacking direction are orthogonal to each other. A direction orthogonal to the extending direction and the stacking direction of the flat tubes 11 is referred to as a short direction. Air passing through the core 14 flows in the short direction. Each of the multiple flat tubes 11 corresponds to an inflow tube. Hereinafter, the extending direction of the flat tube 11 is simply referred to as the extending direction.

  Each of the plurality of corrugated fins 12 is an outer fin that is in direct contact with the conditioned air passing through the heat exchanger 10 outside the flat tube 11. The plurality of corrugated fins 12 increases the heat transfer area with the conditioned air, and promotes heat exchange between the conditioned air and the cooling water. Each corrugated fin 12 of this embodiment extends in a wave shape in the extending direction. That is, each corrugated fin 12 meanders in the stacking direction while extending in the extending direction.

  Among the plurality of corrugated fins 12, each of the corrugated fins 12 other than both ends in the stacking direction is sandwiched between two adjacent flat tubes 11 of the plurality of flat tubes 11. Each corrugated fin 12 is joined to all the flat tubes 11 adjacent to the corrugated fin 12.

  Further, among the plurality of corrugated fins 12, each of the corrugated fins 12 at both ends in the stacking direction is not only the outermost flat tube 11 among the plurality of flat tubes 11 but also the adjacent protective member 15. Be joined.

  The plurality of flat tubes 11 and the plurality of corrugated fins 12 are made of a metal (for example, an aluminum alloy) excellent in thermal conductivity, corrosion resistance, and the like.

  The two protection members 15 are disposed in contact with the corrugated fins 12 along the outer sides of the two corrugated fins 12 disposed at both ends in the stacking direction. Each of the protection members 15 is a member for protecting the core 14 including the adjacent corrugated fins 12. These protective members 15 are made of a metal such as an aluminum alloy.

  The flat tube 11, the corrugated fin 12, and the protective member 15 are integrated by being brazed to each other. For example, each protection member 15 is fixed to the adjacent corrugated fin 12 by brazing, and is fixed to the header tank 16 by brazing at one end, and is fixed to the header tank 17 by brazing at the other end. Is done. Therefore, the protection member 15 corresponds to a restraining member that restrains the header tank 16 and the header tank 17. The header tank 16 corresponds to a first tank, and the header tank 17 corresponds to a second tank.

  Each flat tube 11 is fixed to all adjacent corrugated fins 12 by brazing, and is fixed to the header tank 16 by brazing at one end and brazed to the header tank 17 at the other end. It is fixed with.

  The open end of each flat tube 11 communicates with the internal space of the header tanks 16 and 17. A nozzle 18 is attached to each header tank 16, 17. The cooling water pipe 2 is connected to the nozzle 18 attached to the header tank 16. The cooling water pipe 3 is connected to the nozzle 18 attached to the header tank 17. The header tanks 16 and 17 are connected to a cooling water circuit (not shown) of the engine 1 via cooling water pipes 2 and 3, respectively. A pump 4 is incorporated in the cooling water pipe 2. The header tank 16 corresponds to the first tank, and the header tank 17 corresponds to the second tank.

  When the pump 4 is operated, the cooling water heated by the engine 1 is sent to the header tank 16 through the cooling water pipe 2. The cooling water sent to the header tank 16 branches from the header tank 16 directly into the plurality of flat tubes 11 and flows. As the cooling water flows through the plurality of flat tubes 11, the air-conditioning air and the cooling water exchange heat through the flat tubes 11 and the corrugated fins 12, and the air-conditioning air is warmed. The cooling water that has flowed through the plurality of flat tubes 11 flows directly from the inside of the flat tubes 11 into the header tank 17 and merges, and from the header tank 17 through the cooling water pipe 3 to the cooling water circuit of the engine 1. And return.

  As shown in FIG. 1 and enlarged in FIG. 2, among the plurality of corrugated fins 12, two corrugated fins 12 at both ends in the stacking direction have a constant fin pitch over the entire length in the extending direction. On the other hand, the corrugated fins 12 other than both ends in the stacking direction are formed with short pitch portions 19 at the upstream end of the coolant flow near the header tank 16.

  In each of the corrugated fins 12 other than both ends in the stacking direction, the short pitch portion 19 is disposed in the fin upstream portion 12u on the upstream side of the fin central portion 12c that is equidistant from both ends in the extending direction of the corrugated fin 12. . Here, the upstream side and the downstream side in the corrugated fin 12 are the same as the upstream side and the downstream side of the cooling water flow in the adjacent flat tubes 11.

  The short pitch part 19 has a shorter fin pitch than any other part belonging to the same corrugated fin 12. Here, the fin pitch of a certain corrugated fin 12 refers to an interval in the extending direction of a plurality of bent portions bent in contact with the same flat tube 11 adjacent to the corrugated fin 12. Also in the fin upstream portion 12 u, the portion other than the short pitch portion 19 has a longer fin pitch than the short pitch portion 19.

  Further, in the fin downstream portion 12d on the downstream side of the fin central portion 12c in the same corrugated fin 12, the fin pitch is longer than that of the short pitch portion 19 in all portions.

  In the short pitch portion 19, the fin pitch is shorter than other portions. Therefore, the mass of the corrugated fin 12 per unit length in the extending direction is the largest in the short pitch portion 19. The heat capacity per unit length in the stretching direction is larger in the short pitch portion 19 by the increase in mass.

  The heat capacity of the corrugated fin 12 greatly affects the temperature rise of the flat tube 11 due to the cooling water flowing into the flat tube 11 adjacent to the corrugated fin 12.

  At the same time, the heat capacity of the flat tube 11 greatly affects the temperature rise of the flat tube 11 caused by the cooling water flowing into the flat tube 11.

  Therefore, a certain flat tube 11 and all the corrugated fins 12 adjacent to and in direct contact with the flat tube 11 constitute a single capacity forming portion X that affects the temperature rise of the flat tube 11 as a whole.

  Therefore, the core 14 has the capacity forming portions X as many as the flat tubes 11. Since the two flat tubes 11 may be in contact with the same corrugated fin 12, the two capacity forming portions X may include the same corrugated fin 12.

Of the single capacity forming portion X, the tube upstream portion 11u and the fin upstream portion 12u constitute the upstream side capacity forming portion Xu. Further, in one capacity forming portion X, the tube downstream portion 11d and the fin downstream portion 12d constitute the downstream capacity forming portion Xd.
The fin upstream portion 12u is an upstream adjacent member that is in contact with the tube upstream portion 11u other than the flat tube 11. The fin downstream portion 12d is a downstream adjacent member that is in contact with the tube downstream portion 11d other than the flat tube 11.

  The heat capacity of the upstream capacity forming unit Xu is higher than the heat capacity of the downstream capacity forming unit Xd. Here, the tube upstream portion 11u of a certain flat tube 11 refers to a portion on the upstream side of the coolant flow with respect to the tube central portion 11c that is equidistant from both ends of the flat tube 11 in the extending direction. Further, the tube downstream portion 11d of the flat tube 11 refers to a portion on the downstream side of the cooling water flow with respect to the tube center portion 11c.

  Next, the operation of the heat exchanger 10 will be described. When the engine 1 is operated and the pump 4 is also operated, the cooling water heated by the engine 1 is sent into the header tank 16. The cooling water flows from the header tank 16 into the flat tube 11 of the core 14, and flows into the header tank 17 through these. When the cooling water passes through the flat tube 11, heat exchange is performed between the air-conditioning air flowing in contact with the outer surface of the flat tube 11 and the outer surface of the corrugated fin 12 and the cooling water. That is, the air for air conditioning is warmed and the cooling water is cooled. The air for air conditioning is blown into the vehicle interior by a vehicle air conditioner (not shown), thereby heating the vehicle interior.

  Here, thermal distortion that may occur in the heat exchanger 10 will be described. In recent years, vehicles having a configuration in which the engine is temporarily stopped at the time of temporary stop such as waiting for a signal, that is, a so-called idling stop vehicle has been widely used. The idling stop vehicle is also mounted with the heat exchanger 10 of the present embodiment.

  In the idling stop vehicle, the circulation of the cooling water to the heat exchanger 10 is usually stopped when the engine 1 is stopped. In such a case, the interruption of the cooling water flowing through the heat exchanger 10 with the operation and stop of the engine 1 is frequently repeated.

  If the cooling water heated by the engine 1 begins to flow into the flat tube 11 at repeated repetitions of the cooling water, the temperature of the flat tube 11 is abrupt if no measures are taken unlike this embodiment. To rise. At this time, since the cooling water does not flow through the inside of the protection member 15 and does not come into contact with the cooling water on the surface, the temperature rise is slower than that of the flat tube 11. As a result, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the expansion amount of the protection member 15 that restrains the header tanks 16, 17 and the expansion amount of the flat tube 11. A big discrepancy occurs. This difference in expansion amount causes thermal distortion of the flat tube 11.

  Accordingly, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the thermal distortion is caused by repeated disconnection of the cooling water flowing through the heater core as the engine 1 is operated and stopped. Frequently occurs. This may cause deterioration of the flat tube 11 quickly.

  When the cooling water starts to flow into the flat tube 11 from the header tank 16, the flat tubes 11 adjacent to the corrugated fins 12 at both ends in the stacking direction are protected via the corrugated fins 12 adjacent to the flat tube 11. Heat is conducted to the member 15. Therefore, when the cooling water starts to flow into the flat tube 11 from the header tank 16, the temperature rise of the flat tubes 11 at both ends is delayed more than the other flat tubes 11. Therefore, the flat tube 11 at both ends originally has little contribution to the thermal strain of the flat tube 11.

  In this embodiment, the flat tube 11 is in contact with a short pitch portion 19 as a temperature rise delay means. Since the short pitch portion 19 has a large heat capacity as described above, the temperature rise rate of the flat tube 11 can be suppressed. Thereby, it can suppress that the difference of the temperature increase rate between the flat tube 11 and the protection member 15 becomes large.

  Specifically, while the engine 1 is stopped after being stopped, the pump 4 is also stopped, and the cooling water does not flow through the heat exchanger 10. In the meantime, the cooling water in each flat tube 11 is gradually cooled.

  When the engine 1 restarts, the pump 4 also resumes operation, and the cooling water heated by the engine 1 begins to be pumped to the pump 4. Then, the cooling water heated to a high temperature by the engine 1 starts to flow into the header tank 16 from the cooling water pipe 2 through the nozzle 18. Furthermore, high-temperature cooling water begins to flow from the header tank 16 into each of the plurality of flat tubes 11.

  At this time, the high-temperature cooling water that has flowed into each of the flat tubes 11 is immediately deprived of heat by heat conduction to the short pitch portions 19 of the corrugated fins 12 adjacent to the flat tubes 11. Since the short pitch portion 19 has a large heat capacity, the amount of heat taken away from the cooling water by the short pitch portion 19 is also large. Therefore, the temperature rise rate of the flat tube 11 can be suppressed.

  In particular, for the flat tubes 11 other than both ends in the stacking direction, the short pitch portions 19 are provided on both of the two corrugated fins 12 that are in contact with each other. Therefore, the effect of suppressing the rate of temperature rise when heated cooling water starts to flow into the flat tube 11 is high.

  Compared to this, for the flat tubes 11 at both ends in the stacking direction, the short pitch portion 19 is provided only in the corrugated fin 12 that is not in contact with the protective member 15 out of the two corrugated fins 12 in contact. The corrugated fin 12 in contact with the protective member 15 is not provided with the short pitch portion 19, and the fin pitch is constant along the extending direction.

  One reason for this is that the flat tubes 11 at both ends in the stacking direction are connected to the protective member 15 via only one corrugated fin 12, so that heat easily escapes to the protective member 15, and the short pitch portion This is because it is not necessary to provide 19 on both sides.

  Another reason is that if the corrugated fin 12 in contact with the protective member 15 has the short pitch portion 19, heat easily escapes from the protective member 15 to the corrugated fin 12. If it becomes like that, the temperature rise of the protection member 15 when the heated cooling water begins to flow into the flat tube 11 is delayed, and this is a factor that widens the difference between the temperature rise of the flat tube 11 and the temperature rise of the protection member 15. There is a possibility.

  Therefore, the effect of suppressing the rate of temperature rise when the heated cooling water starts to flow into the flat tube 11 is lower than the other flat tubes 11 for the flat tubes 11 at both ends in the stacking direction.

  In addition, since one short pitch portion 19 is in contact with each of the flat tubes 11 at both ends in the stacking direction, when the heated cooling water starts to flow into the flat tube 11, the short pitch portions 19 It contributes to some extent to the suppression of the temperature rise rate of the flat tube 11.

  When the heated cooling water starts to flow into the flat tube 11, the flattened tube 11 that is the second closest to the nozzle 18 connected to the header tank 16 has the highest temperature rise among the multiple flat tubes 11. It is. This is because although the flat tube 11 closer to the nozzle 18 is more likely to flow in high-temperature cooling water, the flat tube 11 closest to the nozzle 18 easily escapes heat to the protective member 15 as described above. .

  Since the flat tube 11 that is the second closest to the nozzle 18 has the short pitch portions 19 on both sides in the stacking direction, the effect of suppressing the temperature rise rate of the flat tube 11 is high.

  Thus, the difference in elongation due to thermal expansion between the plurality of flat tubes 11 and the protective member 15 is suppressed, and thermal distortion is suppressed.

  And the short pitch part 19 is distribute | arranged to the edge part by the side of the header tank 16 into which a cooling water flows in into the flat tube 11. FIG. The end of the flat tube 11 on the header tank 16 side is the portion of the flat tube 11 where the temperature of the cooling water is the highest. When the short pitch part 19 is arranged in such a part, the effect of the short pitch part 19 that delays the temperature rise of the flat tube 11 is improved.

  The cooling water that has passed through the portion of the flat tube 11 that is in contact with the short pitch portion 19 has already been deprived of heat by the short pitch portion 19, so that the temperature is significantly low. Therefore, the rate of temperature increase in the portion of the flat tube 11 downstream of the portion in contact with the short pitch portion 19 can also be suppressed.

  As described above, the heat capacity of the upstream capacity forming portion Xu is larger than the heat capacity of the downstream capacity forming portion Xd. Therefore, when the heated refrigerant starts to flow into the inflow tube, a relatively large amount of heat is taken from the cooling water in the tube upstream portion 11u to the upstream side capacity forming portion Xu. As a result, the difference between the temperature increase rate of the tube upstream portion 11u and the tube downstream portion 11d and the temperature increase rate of the protection member 15 when the heated cooling water starts to flow into the flat tube 11 is suppressed. . Therefore, the thermal distortion of the flat tube 11 is reduced.

  The protection member 15 extends in the extending direction along the plurality of flat tubes 11. Thus, when the protection member 15 extends along the flat tube 11 in the extending direction, the difference between the temperature increase rate of the flat tube 11 and the temperature increase rate of the restraining member becomes a particular problem. This is because the difference in expansion between the flat tube 11 and the protection member 15 significantly affects the deformation of the flat tube 11. Therefore, when the protective member 15 extends in the extending direction along the flat tube 11, the heat capacity of the upstream capacity forming portion Xu is larger than the heat capacity of the downstream capacity forming portion Xd, so that the effect of reducing thermal distortion is more remarkable. become.

  Further, the upstream capacity forming portion Xu has a larger heat capacity per unit length along the extending direction than any portion of the downstream capacity forming portion Xd. As a result, the effect of reducing thermal distortion can be obtained more efficiently than when the downstream capacity forming portion Xd has a peak of heat capacity per unit length.

Further, in each of the corrugated fins 12 other than the corrugated fins 12 at both ends in the stacking direction, the fin upstream portion 12u includes a short pitch portion 19 whose fin pitch is shorter than any other portion of the corrugated fin 12 as described above. By reducing the thermal distortion using the structure of the corrugated fins 12 provided for heat exchange, an increase in the number of parts can be suppressed.

  Further, between the flat tubes 11 other than both ends in the stacking direction and the protection member 15, another tube into which the cooling water flows directly from the header tank 16 (that is, the flat tubes 11 at both ends in the stacking direction) is arranged. Yes.

  When the protective member 15 that protects the core 14 is a restraining member as in this embodiment, the effect of reducing thermal distortion is greater when another tube is interposed between the protective member 15 and the flat tube 11. high. This is because, when another tube is interposed between the protective member 15 and the flat tube 11, heat hardly moves from the flat tube 11 to the protective member 15.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. In the heat exchanger 10 of this embodiment, the plurality of flat tubes 11 are replaced with the same number of flat tubes 21 and the plurality of corrugated fins 12 are replaced with the same number of corrugated fins 22 in the first embodiment. . The structure of the other heat exchanger 10 is the same as 1st Embodiment. Hereinafter, the extending direction (that is, the longitudinal direction) in which the flat tube 21 extends is simply referred to as the extending direction.

  Each of the corrugated fins 22 has the same shape and material as the corrugated fins 12 at both ends in the stacking direction of the corrugated fins 12 of the first embodiment.

  That is, each corrugated fin 22 has a constant fin pitch in the extending direction of the flat tube 21. None of the corrugated fins 22 has the short pitch portion 19.

  In addition, as shown in FIG. 3, each of the plurality of flat tubes 21 is formed with a thick portion 23 only at the end on the upstream side of the cooling water flow near the header tank 16.

  Each thick portion 23 is disposed in the tube upstream portion 21u upstream of the tube central portion 21c equidistant from both ends in the extending direction of the flat tube 21 to which the thick portion 23 belongs.

  The thick part 23 is a thicker part than any other part belonging to the same flat tube 21. As shown in FIG. 3, the thick portion 23 is formed so that the thickness increases from the downstream side of the cooling water flow toward the upstream side. The thick part 23 having such a shape is formed by plastically deforming the lower end of the flat tube 21 by pressing it along the longitudinal direction of the flat tube 21.

  In addition, in each cross section orthogonal to the extending direction, the thick portion 23 may or may not have the same thickness on the entire circumference surrounding the cooling water. Specifically, the thickness of the surface of the thick portion 23 facing the corrugated fins 22 on both sides in the stacking direction is thicker than any other portion belonging to the same flat tube 21. The same applies to the flat tubes 21 at both ends in the stacking direction and the other flat tubes 21.

  Therefore, also in each of the flat tubes 21 at both ends in the stacking direction, the thickness of the surface of the thick portion 23 facing the corrugated fins 22 on both sides in the stacking direction is larger than any other portion belonging to the same flat tube 21. The wall thickness is thick. Even in this case, when the heated cooling water starts to flow into the flat tube 21, heat escapes from the protection member 15 to the thick portion 23, and the temperature rise rate of the protection member 15 decreases. The possibility is small. This is because corrugated fins 22 exist between the flat tubes 21 at both ends in the stacking direction and the protection member 15.

  Also in the tube upstream portion 21u, portions other than the thick portion 23 are thinner than the thick portion 23. Further, in the tube downstream portion 21d on the downstream side of the tube center portion 21c in the same flat tube 21, the thickness is thinner than the thick portion 23 in all portions.

  Note that the thickness of the flat tube 21 at a certain position in the extending direction is larger as the area occupied by the flat tube 21 is larger in the cross section orthogonal to the extending direction at that position.

  Therefore, the mass of the flat tube 21 per unit length in the extending direction is the largest in the thick portion 23. The heat capacity per unit length in the stretching direction is larger in the thick portion 23 by the increase in mass.

  The heat capacity of the flat tube 21 greatly affects the temperature rise of the flat tube 21 due to the cooling water flowing into the flat tube 21.

  At the same time, the heat capacity of the corrugated fins 22 has a great influence on the temperature rise of the flat tubes 21 caused by the cooling water flowing into the flat tubes 21 adjacent to the corrugated fins 22.

  Therefore, a certain flat tube 21 and all the corrugated fins 22 adjacent to and in direct contact with the flat tube 21 constitute a single capacity forming portion X that affects the temperature rise of the flat tube 21 as a whole.

  Therefore, the core 14 has the capacity forming portions X as many as the flat tubes 21. Since the two flat tubes 21 may be in contact with the same corrugated fin 22, the two capacity forming portions X may include the same corrugated fin 22.

  Of one capacity forming portion X including a certain flat tube 21 and all corrugated fins 22 adjacent thereto, the tube upstream portion 21u and the portion of the corrugated fin 22 connected to the tube upstream portion 21u (that is, the upstream adjacent member) ) Constitutes the upstream side capacitance forming portion Xu. Of the one capacity forming portion X, the tube downstream portion 21d and the portion of the corrugated fin 22 connected to the tube downstream portion 21d (that is, the downstream adjacent member) constitute the downstream capacity forming portion Xd. To do. The heat capacity of the upstream capacity forming unit Xu is higher than the heat capacity of the downstream capacity forming unit Xd.

  As described above, the thick portion 23 is formed by plastically deforming the lower end of the flat tube 21 by pressing it along the longitudinal direction of the flat tube 21. When formed in this way, the length of the thick portion 23 in the extending direction can be shortened as compared to the case where the end portion of the flat tube 21 is bent. As a result, the end portion on the header tank 16 side of the corrugated fin 22 connected to the flat tube 21 is disposed closer to the header tank 17 side in the extending direction than the thick portion 23.

  In this way, the presence of the thick portion 23 reduces the possibility that the corrugated fin 22 abuts on the thick portion 23 and buckles when the flat tube 21 and the corrugated fin 22 are assembled. Is done.

  Moreover, there exists an advantage that the thick part 23 can be formed by the comparatively simple operation | work of pressing a lower end part and carrying out plastic deformation.

  As described above, in the present embodiment, the flat tube 21 is formed with the thick portion 23 as the temperature rise delay means. As described above, since the thick portion 23 has a large heat capacity, the temperature rise rate of the flat tube 21 can be suppressed. Thereby, it can suppress that the difference of the temperature rise rate becomes large between the flat tube 21 and the protection member 15. FIG.

  Specifically, when the engine 1 is restarted for a while after the stop, the pump 4 also resumes operation, and the cooling water heated by the engine 1 starts to be pumped to the pump 4. Then, the cooling water heated to a high temperature by the engine 1 starts to flow into the header tank 16 from the cooling water pipe 2 through the nozzle 18. Furthermore, high-temperature cooling water begins to flow from the header tank 16 into each of the plurality of flat tubes 21.

  At this time, the high-temperature cooling water that has flowed into each flat tube 21 is deprived of heat by heat conduction to the thick portion 23 of the flat tube 21 immediately after flowing. Since the thick portion 23 has a large heat capacity, the amount of heat taken away from the cooling water by the thick portion 23 is also large. Therefore, the temperature rise rate of the flat tube 21 can be suppressed.

  Due to the presence of the thick portion 23 as described above, the same effect as that of the first embodiment can be obtained.

  In addition, by reducing the thermal distortion by using the shape of the flat tube 21 itself that is closest to the cooling water flowing in the flat tube 21, it is possible to suppress an increase in the number of parts of the heat exchanger 10, and The effect of reducing the temperature rise rate of the flat tube 21 is enhanced.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. In the heat exchanger 10 of this embodiment, a plurality of flat tubes 21 are replaced with the same number of flat tubes 31 as compared to the second embodiment. The structure of the other heat exchanger 10 is the same as 2nd Embodiment. Hereinafter, the extending direction (that is, the longitudinal direction) in which the flat tube 31 extends is simply referred to as the extending direction.

  As shown in FIG. 4, each of the plurality of flat tubes 31 of the present embodiment is formed with a thick portion 33 instead of the thick portion 23 only at the end on the upstream side of the cooling water flow near the header tank 16. Has been.

  Each thick portion 33 is arranged in the tube upstream portion 31u on the upstream side of the tube central portion 31c equidistant from both ends in the extending direction of the flat tube 31 to which the thick portion 33 belongs.

  The thick portion 33 is a portion that is thicker than any other portion belonging to the same flat tube 31. As shown in FIG. 4, the thick portion 33 is formed so that the thickness of the thick portion 33 is constant by overlapping two plates from the cooling water flow downstream toward the upstream. The thick portion 33 having such a shape is formed by bending the lower end of the flat tube 21.

  Specifically, the thickness of the surface of the thick portion 23 facing the corrugated fin 22 on both sides in the stacking direction is thicker than any other portion belonging to the same flat tube 31. The same applies to the flat tubes 31 at both ends in the stacking direction and the other flat tubes 31.

  Also in the tube upstream portion 31 u, portions other than the thick portion 33 are thinner than the thick portion 33. Further, in the tube downstream portion 31d on the downstream side of the tube central portion 31c in the same flat tube 31, all the portions are thinner than the thick portion 23.

  Note that the thickness of the flat tube 31 at a certain position in the extending direction is larger as the area occupied by the flat tube 31 is larger in the cross section orthogonal to the extending direction at that position.

  Therefore, the mass of the flat tube 31 per unit length in the extending direction is the largest in the thick portion 33. The heat capacity per unit length in the stretching direction is larger in the thick portion 33 by the increase in mass.

  In addition, a certain flat tube 31 and all the corrugated fins 22 adjacent to and directly in contact with the flat tube 31 constitute a single capacity forming portion X that affects the temperature rise of the flat tube 31 as a whole. Therefore, the core 14 has the capacity forming portions X corresponding to the number of the flat tubes 31.

  Of one capacitance forming portion X including a certain flat tube 31 and all corrugated fins 22 adjacent thereto, a tube upstream portion 31u and a portion connected to the tube upstream portion 31u of the corrugated fin 22 (that is, an upstream adjacent member) ) Constitutes the upstream side capacitance forming portion Xu. Of the one capacity forming portion X, the tube downstream portion 31d and the portion of the corrugated fin 22 connected to the tube downstream portion 31d (that is, the downstream adjacent member) constitute the downstream capacity forming portion Xd. To do. The heat capacity of the upstream capacity forming unit Xu is higher than the heat capacity of the downstream capacity forming unit Xd.

  In addition, as described above, the thick portion 33 is formed by bending the lower end of the flat tube 21. As a result, the end portion on the header tank 16 side of the corrugated fin 22 connected to the flat tube 21 is arranged closer to the header tank 16 side in the extending direction than the end portion on the header tank 17 side of the thick portion 23.

  As described above, in the present embodiment, the thick tube 33 is formed in the flat tube 31 as the temperature increase delay means. Thereby, the effect equivalent to 2nd Embodiment can be acquired.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG. 5, FIG. 6, and FIG. The heat exchanger 10 of the first, second, and third embodiments is a one-pass system, but the heat exchanger 40 of this embodiment is a two-pass system that has a left-right U-turn structure.

  As shown in FIGS. 5 and 6, the heat exchanger 40 of this embodiment includes an upper header tank 41 and a lower header tank 42. The upper header tank 41 corresponds to the first tank, and the lower header tank 42 corresponds to the second tank.

  An inflow nozzle 43 and an outflow nozzle 44 are attached to the front side of the upper header tank 41. One end of the inflow nozzle 43 is connected to the downstream end of the cooling water flow of the cooling water pipe 2 shown in the first embodiment. One end of the outflow nozzle 44 is connected to the cooling water flow upstream end of the cooling water pipe 3 shown in the first embodiment.

  The internal space of the upper header tank 41 is divided into an inflow portion 46 and an outflow portion 47 by a partition 45 transparently shown in FIG. The inflow portion 46 and the outflow portion 47 are arranged in the stacking direction. The other end of the inflow nozzle 43 communicates with the inflow portion 46, and the other end of the outflow nozzle 44 communicates with the outflow portion 47. The lower header tank 42 has no partition or the like, and the internal space is a series.

  A core 48 is disposed between the upper header tank 41 and the lower header tank 42. The core 48 includes a plurality of flat tubes 51, a plurality of flat tubes 52, a plurality of corrugated fins 55, a plurality of corrugated fins 56, and two protective members 15.

  The materials and shapes of the plurality of flat tubes 51 and 52 are the same as those of the flat tube 11 of the first embodiment.

  Each of the plurality of flat tubes 51 is fixed by brazing at the upper end portion to the inflow portion 46 and at the lower end portion to the lower header tank 42. A plurality of flat tubes 51 and a plurality of corrugated fins 55 are alternately stacked one by one, thereby forming a single forward path portion 53. Each of the multiple flat tubes 51 corresponds to an inflow tube.

  Each of the plurality of flat tubes 52 is fixed by brazing the upper end portion to the outflow portion 47 and the lower end portion to the lower header tank 42. A plurality of flat tubes 52 and a plurality of corrugated fins 56 are alternately stacked one by one, thereby forming a single return path portion 54. Each of the plurality of flat tubes 52 corresponds to an outflow tube. Each of the plurality of flat tubes 52 corresponds to a restraining member that restrains the upper header tank 41 and the lower header tank 42.

  The stacking direction of the flat tubes 51 in the forward path portion 53 and the stacking direction of the flat tubes 52 in the return path portion 54 are the same. Hereinafter, the stacking direction of the flat tubes 51 and 52 in the forward path portion 53 and the return path portion 54 is simply referred to as a stacking direction.

  The protective member 15 is fixed by brazing to a corrugated fin 55 provided at an end portion of the forward path portion 53 opposite to the return path portion 54 in the stacking direction. Further, the protective member 15 is also fixed to the corrugated fins 56 provided at the end portion of the return path portion 54 opposite to the forward path portion 53 in the stacking direction. Each of the protection members 15 is a member for protecting the core 48 including the adjacent corrugated fins 12. The protection member 15 is fixed to the upper header tank 41 by brazing and is fixed to the lower header tank 42 by brazing. Therefore, each protection member 15 corresponds to a restraining member that restrains the upper header tank 41 and the lower header tank 42.

  When the pump 4 is operated, the cooling water heated by the engine 1 is sent to the inflow portion 46 through the cooling water pipe 2 and the inflow nozzle 43. The cooling water sent to the inflow portion 46 branches and flows into the plurality of flat tubes 51 directly from the inflow portion 46. As the cooling water flows through the plurality of flat tubes 51, the air-conditioning air and the cooling water exchange heat through the flat tubes 51 and the corrugated fins 55, and the air-conditioning air is warmed and the cooling water is cooled. .

  The cooling water that has flowed through the plurality of flat tubes 51 flows directly from the inside of the flat tubes 51 into the lower header tank 42 and merges, and branches directly from the lower header tank 42 into the plurality of flat tubes 52. Flows in. As the cooling water flows through the plurality of flat tubes 52, the air-conditioning air and the cooling water exchange heat through the flat tubes 52 and the corrugated fins 56, so that the air-conditioning air is warmed and the cooling water is further cooled. The The cooling water that has flowed through the plurality of flat tubes 52 flows directly from the inside of the flat tubes 52 into the outflow portion 47 and merges, and from the outflow portion 47 through the outflow nozzle 44 and the cooling water pipe 3, Return to the circuit.

  As shown in FIG. 6, among the plurality of corrugated fins 55, the corrugated fins 55 adjacent to the protective member 15 have a constant fin pitch over the entire length in the extending direction. All the corrugated fins 55 other than the corrugated fins 55 adjacent to the protection member 15 are formed with short pitch portions 57 at the upstream end of the coolant flow near the upper header tank 41. Moreover, the fin pitch of all the plurality of corrugated fins 56 is constant over the entire length in the extending direction.

  The position and structure of the short pitch portion 57 in each of the corrugated fins 55 are the same as the position and structure of the short pitch portion 19 in each of the corrugated fins 12 of the first embodiment.

  That is, in each of the corrugated fins 55 in which the short pitch portions 57 are formed, the short pitch portions 57 are located on the fin upstream portion 55u upstream of the fin central portion 55c that is equidistant from both ends of the corrugated fin 55 in the extending direction. Has been placed. Here, the upstream side and the downstream side in the corrugated fins 55 are the same as the cooling water flow upstream side and downstream side in the adjacent flat tubes 51.

  The short pitch part 57 has a shorter fin pitch than any other part belonging to the same corrugated fin 55. Here, the fin pitch of a certain corrugated fin 55, 56 refers to an interval in the extending direction of a plurality of bent portions bent in contact with the same flat tube 51, 52 adjacent to the corrugated fin 55, 56. Also in the fin upstream portion 55 u, the portion other than the short pitch portion 57 has a longer fin pitch than the short pitch portion 57.

  Further, in the fin downstream portion 55d on the downstream side of the fin central portion 55c in the same corrugated fin 55, the fin pitch is longer than that of the short pitch portion 57 in all portions. Therefore, the mass of the corrugated fin 55 per unit length in the extending direction is the largest in the short pitch portion 57. The heat capacity per unit length in the stretching direction is larger in the short pitch portion 57 by the increase in mass.

  Further, the fin pitch of the short pitch portion 57 is shorter than the fin pitch of any portion of the corrugated fins 56. Therefore, the heat capacity per unit length in the extending direction of the short pitch portion 57 is larger than the heat capacity per unit length in the extending direction of any part of the corrugated fins 56.

  In addition, a certain flat tube 51 and all corrugated fins 55 adjacent to and in direct contact with the flat tube 51 constitute a single capacity forming portion X that affects the temperature rise of the flat tube 51 as a whole. Of the single capacity forming portion X, the tube upstream portion 51u and the fin upstream portion 55u constitute an upstream side capacity forming portion Xu. Further, in one capacity forming portion X, the tube downstream portion 51d and the fin downstream portion 55d constitute the downstream capacity forming portion Xd. The heat capacity of the upstream capacity forming unit Xu is higher than the heat capacity of the downstream capacity forming unit Xd.

  The fin upstream portion 55u is an upstream adjacent member that is in contact with the tube upstream portion 51u other than the flat tube 51. The fin downstream portion 52 d is a downstream side adjacent member that is in contact with the tube downstream portion 51 d other than the flat tube 51.

  Here, the tube upstream portion 51u of a certain flat tube 51 refers to a portion on the upstream side of the coolant flow with respect to the tube central portion 51c that is equidistant from both ends of the flat tube 51 in the extending direction. Further, the tube downstream portion 51d of the flat tube 51 refers to a portion on the downstream side of the cooling water flow with respect to the tube central portion 51c.

  Next, the operation of the heat exchanger 40 will be described. When the engine 1 is operated and the pump 4 is also operated, the cooling water heated by the engine 1 is sent from the inflow nozzle 43 to the inflow portion 46. The cooling water flows into the flat tube 51 from the inflow portion 46 and flows into these into the lower header tank 42. The cooling water flowing into the lower header tank 42 enters the outflow portion 47 through the flat tube 52 and further flows out from the outflow portion 47 to the outflow nozzle 44.

  When the cooling water passes through the flat tubes 51 and 52, the cooling water in the flat tubes 51 and 52 is cooled by exchanging heat with air for air conditioning. The air-conditioning air heated by this heat exchange is blown into the vehicle interior by a vehicle air conditioner (not shown), thereby heating the vehicle interior. Since the cooling water passes through the flat tube 52 after being cooled through the flat tube 51, the temperature of the cooling water in the flat tube 51 is higher than the temperature of the cooling water in the flat tube 52.

  Here, thermal distortion that may occur in the heat exchanger 40 will be described. As described in the first embodiment, in the idling stop vehicle, the circulation of the cooling water to the heat exchanger 40 is usually stopped when the engine 1 is stopped. In such a case, the cooling water flowing through the heat exchanger 40 is frequently interrupted as the engine 1 is operated and stopped.

  Unlike the present embodiment, no countermeasure should be taken for the temperature of the plurality of flat tubes 51 at the timing when the cooling water heated by the engine 1 starts to flow into the flat tubes 51 in repeated repetition of the cooling water. If so, it will rise rapidly. At this time, since the cooling water directly flowing out from the outflow portion 47 does not flow through the plurality of flat tubes 52, only cooling water having a temperature lower than that in the flat tubes 51 flows. Therefore, the temperature rise of each flat tube 52 is slower than that of each flat tube 51.

  As a result, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the expansion amount of the plurality of flat tubes 52 that restrain the upper header tank 41 and the lower header tank 42, and A large discrepancy occurs between the expansion amounts of the plurality of flat tubes 51. This difference in expansion causes thermal distortion of the flat tubes 51 and 52.

  Therefore, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the cooling water flowing through the heat exchanger 40 is repeatedly interrupted as the engine 1 is operated and stopped. , Thermal distortion occurs frequently. This may cause deterioration of the flat tubes 51 and 52 quickly.

  In the present embodiment, the protective member 15 adjacent to the corrugated fins 55 does not circulate through the cooling water and does not come into contact with the cooling water on the surface, so that the temperature rises compared to the flat tube 51. Is slow. As a result, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the expansion amount of the protective member 15 that restrains the upper header tank 41 and the lower header tank 42, and the flat tube A large discrepancy occurs in the expansion amount of 51. This difference in expansion amount causes thermal distortion of the flat tube 51. However, in the present embodiment, the thermal distortion of the flat tube 51 is most affected by the difference in expansion between the flat tube 51 located closest to the return path portion 54 and the flat tube 52 positioned closest to the forward path portion 53. It is.

  In this embodiment, each flat tube 51 is in contact with a short pitch portion 57 as a temperature rise delay means. As described above, since the short pitch portion 57 has a large heat capacity, the rate of temperature rise of the flat tube 51 can be suppressed. Thereby, it can suppress that the difference of the temperature increase rate between the flat tube 51 and the flat tube 52 becomes large. Moreover, it can suppress that the difference of the temperature increase rate between the flat tube 51 and the protection member 15 becomes large.

  Specifically, while the engine 1 is stopped after being stopped, the pump 4 is also stopped, and the cooling water does not flow through the heat exchanger 40. During that time, the cooling water in each of the flat tubes 51 and 52 gradually cools.

  When the engine 1 restarts, the pump 4 also resumes operation, and the cooling water heated by the engine 1 begins to be pumped to the pump 4. Then, the cooling water heated to a high temperature by the engine 1 starts to flow into the inflow portion 46 from the cooling water pipe 2 through the inflow nozzle 43. Furthermore, high-temperature cooling water begins to flow directly into each of the plurality of flat tubes 51 from the inflow portion 46.

  At this time, the high-temperature cooling water that has flowed into each flat tube 51 is immediately deprived of heat by heat conduction to the short pitch portions 57 of the corrugated fins 55 adjacent to the flat tube 51. Since the short pitch portion 57 has a large heat capacity, the amount of heat taken away from the cooling water by the short pitch portion 57 is also large. Therefore, the temperature rise rate of the flat tube 51 can be suppressed.

  Note that the short pitch portion 57 is not provided in the corrugated fin 55 adjacent to the protective member 15 because if the short pitch portion 57 exists in the corrugated fin 55, heat escapes from the protective member 15 to the corrugated fin 55. This is because it becomes easier.

  Thus, the difference in elongation due to thermal expansion between the plurality of flat tubes 51 and the plurality of flat tubes 52 is suppressed, and thermal distortion is suppressed. Moreover, the difference of the elongation amount by the thermal expansion of the several flat tube 51 and the protection member 15 is suppressed, and a thermal distortion is suppressed.

  And the short pitch part 57 is distribute | arranged to the edge part by the side of the inflow part 46 into which the cooling water flows in into the flat tube 51, ie, the part with the highest temperature of a cooling water. Therefore, the effect of the short pitch portion 57 is improved. Moreover, since the cooling water which passed through the part which touches the short pitch part 57 among the flat tubes 51 has already been deprived of the heat by the short pitch part 57, temperature is significantly low. Therefore, the rate of temperature rise in the portion of the flat tube 51 downstream of the portion in contact with the short pitch portion 57 is also suppressed.

  As described above, in the heat exchanger 40 having the left and right U-turn flow, the flat tube 52 in which the temperature of the heat transfer fluid flowing inside is lower than that of the flat tube 51 is the restraining member. Also in that case, when the heat capacity of the upstream capacity forming portion Xu is larger than the heat capacity of the downstream capacity forming portion Xd, the tube upstream portion 51u and the tube downstream when the heated cooling water starts to flow into the flat tube 51. The difference between the temperature increase rate of the portion 51d and the temperature increase rate of the outflow tube is suppressed. Therefore, the thermal distortion of the flat tubes 51 and 52 is reduced.

(Fifth embodiment)
Next, a fourth embodiment will be described with reference to FIGS. 8, 9, 10, 11, and 12. FIG. Although the heat exchanger 10 of 1st, 2nd, 3rd embodiment is a 1 pass system, the heat exchanger 60 of this embodiment is a 2 pass system of front-back U-turn structure.

  As shown in FIGS. 8 and 9, the heat exchanger 60 of this embodiment includes an upper header tank 61 and a lower header tank 62. The upper header tank 61 corresponds to the first tank, and the lower header tank 62 corresponds to the second tank.

  An inflow nozzle 63 and an outflow nozzle 64 are attached to the end of the upper header tank in the stacking direction. One end of the inflow nozzle 63 is connected to the downstream end of the cooling water flow of the cooling water pipe 2 shown in the first embodiment. One end of the outflow nozzle 64 is connected to the cooling water flow upstream end of the cooling water pipe 3 shown in the first embodiment.

  The inner space of the upper header tank 41 is divided into an inflow portion 66 and an outflow portion 67 by a partition 65 transparently shown in FIG. The inflow portion 66 and the outflow portion 67 are arranged in a short direction perpendicular to both the stacking direction and the extending direction. The other end of the inflow nozzle 63 communicates with the inflow portion 66, and the other end of the outflow nozzle 64 communicates with the outflow portion 67. The lower header tank 62 is not partitioned and the internal space is a series.

  A core 68 is disposed between the upper header tank 61 and the lower header tank 62. As shown in FIGS. 10, 11, and 12, the core 68 includes a plurality of flat tubes 71, a plurality of flat tubes 72, a plurality of corrugated fins 75, a plurality of corrugated fins 78, and two protections. A member 15 is provided. The materials and shapes of the plurality of flat tubes 51 and 52 are the same as those of the flat tube 11 of the first embodiment.

  Each of the plurality of flat tubes 71 is fixed by brazing the upper end portion to the inflow portion 66 and the lower end portion to the lower header tank 62. A plurality of flat tubes 71 and a plurality of corrugated fins 75 are alternately stacked one by one, so that a single forward path portion 76 is configured. Each of the multiple flat tubes 71 corresponds to an inflow tube.

  Each of the plurality of flat tubes 72 is fixed to the outflow portion 67 at the upper end portion and to the lower header tank 62 at the lower end portion by brazing. A plurality of flat tubes 72 and a plurality of corrugated fins 78 are alternately stacked one by one to form a single return path portion 54. Each of the plurality of flat tubes 72 corresponds to an outflow tube. Each of the plurality of flat tubes 72 corresponds to a restraining member that restrains the upper header tank 61 and the lower header tank 62.

  The stacking direction of the flat tubes 71 in the forward path portion 76 and the stacking direction of the flat tubes 72 in the return path portion 79 are parallel. Hereinafter, the stacking direction of the flat tubes 71 and 72 in the forward path portion 76 and the return path portion 79 is simply referred to as a stacking direction. The forward path portion 76 and the return path portion 79 overlap in the short direction described above.

  One of the two protective members 15 is fixed to the corrugated fins 75 and 78 at one end in the stacking direction of the core 68 by brazing. The other of the two protective members 15 is also fixed by brazing to the corrugated fins 75 and 78 at the other end of the core 68 in the stacking direction. Each of the protection members 15 is a member for protecting the core 68 including the adjacent corrugated fins 75 and 78. The protection member 15 is fixed to the upper header tank 61 and the lower header tank 62 by brazing.

  When the pump 4 is operated, the cooling water warmed by the engine 1 is sent to the inflow portion 66 through the cooling water pipe 2 and the inflow nozzle 63. The cooling water sent to the inflow portion 66 branches directly from the inflow portion 66 into the plurality of flat tubes 71 and flows. As the cooling water flows through the plurality of flat tubes 71, the air-conditioning air and the cooling water exchange heat through the flat tubes 71 and the corrugated fins 75, and the air-conditioning air is warmed and the cooling water is cooled. .

  The cooling water that has flowed through the plurality of flat tubes 71 flows directly from the inside of the flat tubes 71 into the lower header tank 62 and merges, and branches directly from the lower header tank 62 into the plurality of flat tubes 72. Flows in. As the cooling water flows through the plurality of flat tubes 72, the air-conditioning air and the cooling water exchange heat through the flat tubes 72 and the corrugated fins 78, so that the air-conditioning air is warmed and the cooling water is further cooled. The The cooling water that has flowed through the plurality of flat tubes 72 flows directly into the outflow portion 67 from the inside of the flat tube 72 and merges, and from the outflow portion 67 through the outflow nozzle 64 and the cooling water pipe 3, Return to the circuit.

  As shown in FIGS. 9 and 11, all of the plurality of corrugated fins 75 are formed with a short pitch portion 77 at an end portion on the upstream side of the coolant flow near the upper header tank 61. Further, in all of the plurality of corrugated fins 78, the fin pitch is constant over the entire length in the extending direction.

  The position and structure of the short pitch portion 77 in each of the corrugated fins 75 are the same as the position and structure of the short pitch portion 19 in each of the corrugated fins 12 of the first embodiment.

  That is, in each of the corrugated fins 75 in which the short pitch portions 77 are formed, the short pitch portions 77 are formed on the fin upstream portion 75u on the upstream side of the fin central portion 75c that is equidistant from both ends in the extending direction of the corrugated fins 75. Has been placed. Here, the upstream side and the downstream side in the corrugated fins 75 are the same as the upstream and downstream sides of the cooling water flow in the adjacent flat tubes 71.

  The short pitch part 77 has a shorter fin pitch than any other part belonging to the same corrugated fin 75. Here, the fin pitch of a certain corrugated fin 75, 78 refers to an interval in the extending direction of a plurality of bent portions bent in contact with the same flat tube 71, 72 adjacent to the corrugated fin 75, 78. Also in the fin upstream portion 75 u, the portion other than the short pitch portion 77 has a longer fin pitch than the short pitch portion 77.

  Further, in the fin downstream portion 75d on the downstream side of the fin central portion 75c in the same corrugated fin 75, the fin pitch is longer than that of the short pitch portion 77 in all portions. Therefore, the mass of the corrugated fin 75 per unit length in the extending direction is the largest in the short pitch portion 77. The heat capacity per unit length in the stretching direction is increased in the short pitch portion 77 by the increase in mass.

  Further, the fin pitch of the short pitch portion 77 is shorter than the fin pitch of any portion of the corrugated fin 78. Therefore, the heat capacity per unit length in the extending direction of the short pitch portions 77 is larger than the heat capacity per unit length in the extending direction of any part of the corrugated fins 78.

  Further, a certain flat tube 71 and all corrugated fins 75 adjacent to and in direct contact with the flat tube 71 constitute a single capacity forming portion X that affects the temperature rise of the flat tube 71 as a whole. Of one capacity forming portion X, the tube upstream portion 71u and the fin upstream portion 75u constitute an upstream side capacity forming portion Xu. Further, in one capacity forming portion X, the tube downstream portion 71d and the fin downstream portion 75d constitute the downstream capacity forming portion Xd. The heat capacity of the upstream capacity forming unit Xu is higher than the heat capacity of the downstream capacity forming unit Xd.

  The fin upstream portion 75u is an upstream adjacent member that is in contact with the tube upstream portion 71u other than the flat tube 71. The fin downstream portion 72d is a downstream adjacent member that is in contact with the tube downstream portion 71d other than the flat tube 71.

  Here, the tube upstream portion 71u of a certain flat tube 71 refers to a portion on the upstream side of the coolant flow with respect to the tube center portion 71c that is equidistant from both ends of the flat tube 71 in the extending direction. Further, the tube downstream portion 71d of the flat tube 71 refers to a portion on the downstream side of the coolant flow with respect to the tube center portion 71c.

  Next, the operation of the heat exchanger 60 will be described. When the engine 1 is operated and the pump 4 is also operated, the cooling water heated by the engine 1 is sent from the inflow nozzle 63 to the inflow portion 66. The cooling water flows into the flat tube 71 from the inflow portion 66 and flows into the lower header tank 62 through these. The cooling water that has flowed into the lower header tank 62 passes through the flat tube 72, enters the outflow portion 67, and then flows out from the outflow portion 67 to the outflow nozzle 64.

  When the cooling water passes through the flat tubes 71 and 72, the cooling water in the flat tubes 71 and 72 is cooled by exchanging heat with air for air conditioning. The air-conditioning air heated by this heat exchange is blown into the vehicle interior by a vehicle air conditioner (not shown), thereby heating the vehicle interior. Since the cooling water passes through the flat tube 72 after being cooled through the flat tube 71, the temperature of the cooling water in the flat tube 71 is higher than the temperature of the cooling water in the flat tube 72.

  Here, thermal distortion that may occur in the heat exchanger 60 will be described. As described in the first embodiment, in the idling stop vehicle, the circulation of the cooling water to the heat exchanger 60 is usually stopped when the engine 1 is stopped. In such a case, the cooling water flowing through the heat exchanger 60 is frequently interrupted as the engine 1 is operated and stopped.

  The cooling water heated by the engine 1 starts to flow into the flat tubes 71 in repeated repetitions of the cooling water, and the temperature of the plurality of flat tubes 71 must take no measures unlike this embodiment. If so, it will rise rapidly. At this time, since the cooling water directly flowing out from the outflow portion 67 does not flow through the plurality of flat tubes 72, only cooling water having a temperature lower than that in the flat tube 71 flows. Therefore, the temperature rise of each flat tube 72 is slower than that of each flat tube 71.

  As a result, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the expansion amount of the plurality of flat tubes 72 that restrain the upper header tank 61 and the lower header tank 62, and A large discrepancy occurs between the expansion amounts of the plurality of flat tubes 71. This difference in expansion amount causes thermal distortion of the flat tubes 71 and 72.

  Therefore, unlike the present embodiment, if the heat capacity of the capacity forming portion X is constant along the extending direction, the cooling water flowing through the heat exchanger 60 is repeatedly interrupted as the engine 1 is operated and stopped. , Thermal distortion occurs frequently. This may cause deterioration of the flat tubes 71 and 72 quickly.

  In the present embodiment, each flat tube 71 is in contact with a short pitch portion 77 as a temperature rise delay means. Since the short pitch portion 77 has a large heat capacity as described above, the temperature rise rate of the flat tube 71 can be suppressed. Thereby, it can suppress that the difference of the temperature increase rate between the flat tube 71 and the flat tube 72 becomes large.

  Specifically, while the engine 1 is stopped after being stopped, the pump 4 is also stopped, and the cooling water does not flow through the heat exchanger 60. During that time, the cooling water in each of the flat tubes 71 and 72 gradually cools.

  When the engine 1 restarts, the pump 4 also resumes operation, and the cooling water heated by the engine 1 begins to be pumped to the pump 4. Then, the cooling water heated to a high temperature by the engine 1 starts to flow into the inflow portion 66 from the cooling water pipe 2 through the inflow nozzle 63. Furthermore, high-temperature cooling water begins to flow directly from the inflow portion 66 into each of the plurality of flat tubes 71.

  At this time, the high-temperature cooling water that has flowed into each flat tube 71 is immediately deprived of heat by heat conduction to the short pitch portions 77 of the corrugated fins 75 adjacent to the flat tube 71. Since the short pitch portion 77 has a large heat capacity, the amount of heat taken away from the cooling water by the short pitch portion 77 is also large. Therefore, the temperature rise rate of the flat tube 71 can be suppressed. Thus, the difference in elongation due to thermal expansion between the plurality of flat tubes 71 and the plurality of flat tubes 72 is suppressed, and thermal distortion is suppressed.

  And the short pitch part 77 is distribute | arranged to the edge part by the side of the inflow part 66 into which the cooling water flows in into the flat tube 71, ie, the part with the highest temperature of a cooling water. Therefore, the effect of the short pitch portion 77 is improved. Moreover, since the cooling water which passed through the part which touches the short pitch part 77 among the flat tubes 71 has already been deprived of the heat by the short pitch part 77, the temperature is significantly low. Accordingly, the rate of temperature rise in the portion of the flat tube 71 downstream of the portion in contact with the short pitch portion 77 is also suppressed.

  As described above, in the heat exchanger 60 having the front and rear U-turn flow, the flat tube 72 whose temperature of the heat transfer fluid flowing inside is lower than that of the flat tube 71 is a restraining member. Also in that case, when the heat capacity of the upstream capacity forming portion Xu is larger than the heat capacity of the downstream capacity forming portion Xd, the tube upstream portion 71u and the tube downstream when the heated cooling water starts to flow into the flat tube 71. The difference between the temperature increase rate of the portion 71d and the temperature increase rate of the flat tube 72 is suppressed. Therefore, thermal distortion is reduced in both the flat tube 72 and the flat tube 71.

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case. In particular, when a plurality of values are exemplified for a certain amount, it is also possible to adopt a value between the plurality of values unless specifically stated otherwise and in principle impossible. . Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like. The present invention also allows the following modifications to the above embodiments. In addition, the following modifications can select application and non-application to the said embodiment independently. In other words, any combination of the following modifications can be applied to the above-described embodiment.

(Modification 1)
In the second embodiment, a plurality of corrugated fins 22 having no short pitch portions are employed in place of the plurality of corrugated fins 12 having the short pitch portions 19 in the first embodiment. Furthermore, in the second embodiment, a plurality of flat tubes 21 having thick portions 23 are employed instead of the plurality of flat tubes 11 in the first embodiment.

  Such a change of the second embodiment with respect to the first embodiment can also be applied to the fourth embodiment. Specifically, instead of the plurality of corrugated fins 55 having the short pitch portions 57, a plurality of corrugated fins 22 having no short pitch portions are employed, and the thick wall portions 23 are substituted for the plurality of flat tubes 51. You may employ | adopt the several flat tube 21 which has these.

  Such a change of the second embodiment with respect to the first embodiment can also be applied to the fourth embodiment. Specifically, instead of the plurality of corrugated fins 55 having the short pitch portions 57, a plurality of corrugated fins 22 having no short pitch portions are employed, and the thick wall portions 23 are substituted for the plurality of flat tubes 51. You may employ | adopt the several flat tube 21 which has these. Moreover, you may give a change like 3rd Embodiment to what changed in this way.

  Moreover, the change of 2nd Embodiment with respect to such 1st Embodiment is applicable also to 5th Embodiment. Specifically, instead of the plurality of corrugated fins 75 having the short pitch portions 77, a plurality of corrugated fins 22 having no short pitch portions are employed, and the thick wall portions 23 are substituted for the plurality of flat tubes 71. You may employ | adopt the several flat tube 21 which has these. Moreover, you may give a change like 3rd Embodiment to what changed in this way.

(Modification 2)
The corrugated fins 12, 22, 32, 55, 56, 75, and 78 of the above embodiments are not necessarily corrugated fins. The fin having the short pitch portion needs to be a fin that can define the interval between the portions of the fin in the extending direction.

(Modification 3)
In the above embodiment, a short pitch portion and a thick portion are employed as members for increasing the heat capacity of the upstream capacity forming portion Xu to be larger than the heat capacity of the downstream capacity forming portion Xd. However, a member other than these may be used as a member for making the heat capacity of the upstream capacity forming portion Xu larger than the heat capacity of the downstream capacity forming portion Xd. For example, a cold storage material that is disposed in the gap between the corrugated fins and directly contacts the inflow tube may be used.

(Modification 4)
Moreover, in each said embodiment, in the capacity | capacitance formation part X, as a part whose heat capacity per unit length along an extending | stretching direction is larger than any other part of the capacity | capacitance formation part X, it is a short pitch part and a thick part. Only one of them is placed. However, in the capacity forming part X, both the short pitch part and the thick part are arranged as a part where the heat capacity per unit length along the extending direction is larger than any other part of the capacity forming part X. Also good.

(Summary)
According to the first aspect shown in a part or all of the above embodiments, the heat capacity of the upstream capacity forming unit is larger than the heat capacity of the downstream capacity forming unit Xd.

  According to a second aspect, the restraining member extends along the inflow tube in the same direction as the inflow tube extending direction, is fixed to the first tank at one end in the extending direction, and is fixed at the other end in the extending direction. Fixed to 2 tanks.

  As described above, when the restraining member extends along the inflow tube in the same direction as the extending direction of the inflow tube, the difference between the temperature rise rate of the inflow tube and the temperature rise rate of the restraining member becomes a particular problem. Therefore, when the restraining member extends along the inflow tube in the same direction as the extension direction of the inflow tube, the heat capacity of the upstream capacity forming portion is larger than the heat capacity of the downstream capacity forming portion, thereby reducing thermal distortion. Become more prominent.

  Moreover, according to the 3rd viewpoint, an upstream capacity | capacitance formation part contains the part whose heat capacity per unit length along an extending | stretching direction is larger than any part of a downstream capacity | capacitance formation part. As a result, the effect of reducing thermal distortion can be obtained more efficiently than in the case where the heat capacity peak per unit length exists in the downstream capacity forming portion.

  Moreover, according to the 4th viewpoint, a heat exchanger is provided with the fin which accelerates | stimulates the heat exchange with the heat-medium fluid in an inflow tube, and air by contacting a tube upstream part and a tube downstream part, and contacting air. The upstream capacity forming portion includes a portion of the fin that contacts the tube upstream portion, and the downstream capacity forming portion includes a portion of the fin that contacts the tube downstream portion. Moreover, the fin upstream part which belongs to an upstream capacity | capacitance formation part among fins contains the short pitch part whose fin pitch in an extending | stretching direction is shorter than any other part of a fin. In this way, by reducing the thermal distortion using the fin structure originally provided for heat exchange, it is possible to suppress an increase in the number of parts.

  According to the fifth aspect, the tube upstream portion includes a thick portion whose thickness is thicker than any other portion of the inflow tube. In this way, by reducing the thermal distortion by utilizing the shape of the inflow tube that is closest to the heat transfer fluid flowing in the inflow tube, the increase in the number of parts can be suppressed and the temperature of the inflow tube is increased. The speed reduction effect is enhanced.

  Further, according to the sixth aspect, the restraining member includes a protective member that protects the inflow tube, and there is another tube between which the heat transfer fluid flows directly from the first tank between the inflow tube and the protective member. Has been placed.

  Thus, when the protective member that protects the inflow tube is a restraining member, the effect of reducing thermal distortion is higher when another tube is interposed between the protective member and the inflow tube. This is because, when another tube is interposed between the protective member and the inflow tube, it is difficult for heat to move from the inflow tube to the protective member.

  According to the seventh aspect, the restraining member includes an outflow tube through which the heat medium fluid flows from the second tank and from which the heat medium flows out. As described above, in the heat exchanger having a U-turn flow, the outflow tube whose temperature of the heat transfer fluid flowing inside is lower than that of the inflow tube is a restraining member. Also in this case, when the heat capacity of the upstream capacity forming portion is larger than that of the downstream capacity forming portion, the heated heat medium fluid starts to flow into the inflow tube, and the upstream portion of the inflow tube and the downstream portion of the inflow tube The difference between the rate of increase in the temperature and the rate of increase in the temperature of the outflow tube is suppressed. Therefore, the thermal distortion of the first tank and the second tank fixed to the restraining member is reduced.

10, 40, 60 Heat exchanger 11, 21, 31, 51, 52, 71, 72 Flat tube 12, 22, 32, 55, 56, 75, 78 Corrugated fin 14, 48, 68 Core 15 Protective member 19, 57 77 Short pitch 23, 33 Thick part

Claims (7)

A heat exchanger for exchanging heat between the heat transfer fluid and air,
A first tank (16, 41, 61) into which the heat transfer fluid flows from the outside of the heat exchanger;
An inflow tube (11, 21, 31, 51, 71) fixed to the first tank and into which the heat transfer fluid flows directly from the first tank;
A second tank (17, 42, 62) fixed to the inflow tube and into which the heat transfer fluid flows directly from the inflow tube;
The heat transfer fluid does not flow directly from the first tank and is fixed to the first tank and the second tank so as to restrain the first tank and the second tank (15, 52). 72), and
The side closer to the first tank than the tube central portion (11c, 21c, 31c, 51c, 71c) equidistant from both ends of the inflow tube along the extending direction of the inflow tube is the tube upstream portion (11u, 21u, 31u). , 51u, 71u), and the tube downstream portion (11d, 21d, 31d, 51d, 71d) is closer to the second tank than the central portion of the tube along the extending direction of the inflow tube,
The heat capacity of the upstream capacity forming portion (Xu) composed of the upstream adjacent member (12u, 55u, 75u) in contact with the tube upstream portion and the tube upstream portion is determined by the downstream adjacent member (12d, 12d, in contact with the tube downstream portion). 55d, 75d) and a heat exchanger larger than the heat capacity of the downstream capacity forming part (Xd) comprising the tube downstream part.   The restraint member extends along the inflow tube in the same direction as the extension direction of the inflow tube, is fixed to the first tank at one end in the extension direction, and is connected to the second tank at the other end in the extension direction. The heat exchanger according to claim 1, which is fixed.   The said upstream capacity | capacitance formation part contains the part (19,23,33,57,77) whose heat capacity per unit length along the said extending | stretching direction is larger than any part of the said downstream capacity | capacitance formation part. Or the heat exchanger of 2. Fins (12, 22, 32) that promote heat exchange between the heat transfer fluid in the inflow tube and the air by being in contact with the air while being in contact with the tube upstream portion and the tube downstream portion,
The upstream capacity forming portion includes a portion of the fin that contacts the tube upstream portion, and the downstream capacity forming portion includes a portion of the fin that contacts the tube downstream portion,
Among the fins, the fin upstream portion (12u, 55u, 75u) belonging to the upstream capacity forming portion has a short pitch portion (19, 57, 77) in which the fin pitch in the extending direction is shorter than any other portion of the fin. The heat exchanger according to any one of claims 1 to 3, comprising:   The heat exchanger according to any one of claims 1 to 4, wherein the upstream portion of the tube includes a thick portion (23, 33) whose thickness is thicker than any other portion of the inflow tube.   The restraint member includes a protection member (15) that protects the inflow tube, and another tube (11) into which the heat transfer fluid flows directly from the first tank is interposed between the inflow tube and the protection member. , 51) is arranged. The heat exchanger according to any one of claims 1 to 5.   The heat according to any one of claims 1 to 6, wherein the restraining member includes an outflow tube (52, 72) through which a heat transfer fluid flows from the second tank and from which the heat transfer medium flows out to the first tank. Exchanger.

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