Patent ID: 12241687

DESCRIPTION OF EMBODIMENTS

To begin with, examples of relevant techniques will be described.

For example, as an evaporator provided in a heat pump system, a heat exchanger recovers heat from air by exchanging heat with a heat medium such as a refrigerant. In the heat exchanger, a low-temperature heat medium that passes through the inside of the tube exchanges heat with air that passes through the outside of the tube.

The air passing through the heat exchanger contains water vapor. Therefore, when the air is cooled as passing through the outside of the tube, the water vapor contained in the air becomes condensed water and adheres to the surface of the tube or fin. The condensed water may form frost and adhere to the surface of tube or fin.

The condensed water and water generated by melting the frost are referred to “condensed water”. The condensed water moves downward due to gravity along the surface of the tube or fin.

The heat exchanger has a reinforcing plate, which is a plate-shaped member, in order to sandwich and protect tubes and fins. When the tubes extend in the horizontal direction and are arranged in the vertical direction, the reinforcing plate is arranged at the upper side and the lower side in the vertical direction. Specifically, a reinforcing plate is arranged on the upper side of the uppermost tube and another reinforcing plate is arranged on the lower side of the lowermost tube.

In the heat exchanger having such a configuration, there is a concern that the condensed water that has moved downward due to gravity stays on the upper surface of the reinforcing plate arranged at the lower side. Therefore, in a heat exchanger, a hole for discharging the cooling water to the lower side is formed in the reinforcing plate (side plate) on the lower side.

The reinforcing plate is required to have a certain degree of rigidity. Therefore, the present inventors study a configuration for forming a bent portion that protrudes downward with respect to the reinforcing plate. If such a bent portion is formed in a straight line so as to extend in the longitudinal direction of the reinforcing plate, that is, along the longitudinal direction of the tube, the rigidity of the reinforcing plate can be increased.

In the reinforcing plate having such a configuration, the condensed water tends to flow into the bent portion. Therefore, it is conceivable to form a discharge hole in the bent portion for discharging the cooling water. However, the condensed water existing inside the bent portion has a relatively strong surface tension to stay in the bent portion. For example, it is difficult to sufficiently discharge the condensed water simply by forming a discharge hole that passing through the bottom of the bent portion. It is not preferable from the viewpoint of cost to separately provide a drainage guide in order to promote the discharge of condensed water.

The present disclosure provides a heat exchanger capable of sufficiently draining the condensed water.

According to the present disclosure, a heat exchanger exchanges heat between heat medium and air. The heat exchanger includes: a plurality of tubes arranged in an up-down direction, through which the heat medium passes; and a reinforcing plate arranged on a lower side of a lowermost tube of the plurality of tubes. The reinforcing plate has a bent portion protruding downward and extending along a longitudinal direction of the tube. The bent portion includes at least one discharge hole to discharge a condensed water flowing from an upper side toward a lower side. The bent portion has a lower end to define an upstream region upstream of the lower end in a flow direction of air and a downstream region downstream of the lower end in a flow direction of air. The discharge hole is formed by an upstream rib extending from the upper side toward the discharge hole in the upstream region and a downstream rib extending from the upper side toward the discharge hole in the downstream region. A height dimension of the upstream rib is different from a height dimension of the downstream rib partially at least along the longitudinal direction of the tube.

In the heat exchanger having such a configuration, the reinforcing plate arranged on the lower side of the tubes has the bent portion protruding toward the lower side. Further, a discharge hole for discharging the condensed water downward is formed in the bent portion. As a result, the condensed water flows into the bent portion from the upper side and then is discharged to the outside through the discharge hole.

The discharge hole is formed so that the height dimension of the upstream rib and the height dimension of the downstream rib are different from each other partially at least along the longitudinal direction of the tube. In other words, at least partially, one of the upstream rib and the downstream rib protrudes further downward than the other, and the protruding part faces the discharge hole. In such a configuration, the surface tension acting on the condensed water in the vicinity of the discharge hole can be made relatively small. Therefore, the condensed water moves downward along the protruding part and is smoothly discharged to the outside from the discharge hole facing the protruding part.

As described above, in the heat exchanger having the above configuration, it is possible to sufficiently drain the condensed water by forming the discharge hole at position deviated from the center of the bent portion in the flow direction of air, not at the center of the bent portion in the flow direction of air.

According to the present disclosure, there is provided a heat exchanger capable of sufficiently draining a condensed water.

Hereinafter, embodiments will be described with reference to the attached drawings. In order to facilitate the ease of understanding, the same reference numerals are attached to the same constituent elements in the drawings where possible, and redundant explanations are omitted.

A heat exchanger10according to a first embodiment will be described. The heat exchanger10is mounted on a vehicle (not shown). As shown inFIG.1, the heat exchanger10is configured as a composite heat exchanger in which a radiator100and an evaporator200are combined and integrated.

The radiator100is a heat exchanger for cooling a cooling water whose temperature becomes high after passing through a heating element (not shown), and the cooling water exchanges heat with air. The “heating element” means a device mounted on the vehicle and requiring cooling, for example, an internal combustion engine, an intercooler, a motor, an inverter, a battery, or the like. The evaporator200is a part of an air conditioner (not shown) mounted on the vehicle, and is a heat exchanger for evaporating a liquid phase refrigerant by heat exchange with air. As described above, the heat exchanger10is configured as a heat exchanger that exchanges heat between the heat medium and the air. In the radiator100, the cooling water corresponds to a “heat medium”. In the evaporator200, the refrigerant corresponds to a “heat medium”.

First, the configuration of the radiator100will be described. The radiator100includes tanks110and120, tubes130, and fins140. Note that the fins140are not shown inFIG.1.

The tank110,120is a container for temporarily storing the cooling water, which is a heat medium. Each of the tanks110and120is an approximately cylindrical container and arranged such that longitudinal direction of the tank110,120is positioned along the vertical direction. The tanks110and120are arranged at positions separated from each other in the horizontal direction, and the tubes130and the fins140are arranged between the tanks110and120.

The tank110is integrated with the tank210of the evaporator200. Similarly, the tank120is integrated with the tank220of the evaporator200.FIG.1shows a state in which the tank110and the tank210are removed from the heat exchanger10in order to show the internal configuration of the tank110and the tank210.

The tank110has receiving portions111and112for receiving the cooling water after passing through the heating element. The receiving portion111is provided at a position on the upper side of the tank110. The receiving portion112is provided at a position on the lower side of the tank110.

As shown inFIG.1, the internal space of the tank110is divided into upper and lower parts by a separator S3. The cooling water from the receiving portion111flows into the upper part of the internal space of the tank110above the separator S3. The cooling water from the receiving portion112flows into the lower part of the internal space of the tank110below the separator S3.

The tank120has discharge portions121and122for discharging the cooling water to the outside after being subjected to heat exchange. The discharge portion121is provided at a position on the upper side of the tank120. The discharge portion122is provided at a position on the lower side of the tank120.

A separator similar to the separator S3is arranged inside the tank120at a position at the same height as the separator S3. The internal space of the tank120is divided into upper and lower parts by the separator. The cooling water that has flowed into the internal space above the separator in the tank120is discharged to the outside from the discharge portion121. The cooling water that has flowed into the internal space below the separator in the tank120is discharged to the outside from the discharge portion122.

The tube130is a tubular member through which the cooling water passes, and the radiator100has the plural tubes130. Each tube130is an elongated straight tube and is arranged so as to extend along the horizontal direction. One end of the tube130is connected to the tank110, and the other end is connected to the tank120. Accordingly, the inside space of the tank110communicates with the inside space of the tank120through the tubes130.

The tubes130are arranged in the vertical direction, that is, along the longitudinal direction of the tank110. The fin140is arranged between the tubes130adjacent to each other in the vertical direction, but the fins140are not shown inFIG.1.

The cooling water supplied from the outside to the tank110flows into the tank120through the tube130. As the cooling water passes through the inside of the tube130, the cooling water is cooled by the air passing through the outside of the tube130such that the temperature is lowered. The flow direction of the air is perpendicular to both the longitudinal direction of the tank110and the longitudinal direction of the tube130, and air flows from the radiator100to the evaporator200. A fan (not shown) for sending air in the flow direction is provided in the vicinity of the heat exchanger10.

The fin140is a corrugated fin formed by bending a metal plate in a wavy shape. As described above, the fin140is arranged at positions between the tubes130adjacent to each other in the vertical direction. That is, in the radiator100, the fins140and the tubes130are stacked so as to be alternately arranged in the vertical direction.FIG.2is an enlarged view showing the area A inFIG.1. As shown inFIG.2, the top of the wavy fin140abuts and is brazed to the surface of the tube130adjacent in the vertical direction.

When the cooling water passes through the inside of the tube130, the heat of the cooling water is transferred to the air through the tube130and also to the air through the tube130and the fin140. That is, the contact area with the air is increased by the fin140, thereby the heat exchange between the air and the cooling water is efficiently performed.

The configuration of the evaporator200will be described with reference toFIG.1. The evaporator200includes tanks210and220, tubes230, and fins140.

The tank210,220is a container for temporarily storing the refrigerant, which is a heat medium. Each of the tanks110and120has an approximately cylindrical shape and is arranged such that longitudinal direction of the tank110,120is positioned along the vertical direction. The tanks210and220are arranged at positions separated from each other in the horizontal direction, and the tubes230and the fins140are arranged between the tanks210and220.

As described above, the tank210is integrated with the tank110of the radiator100. Similarly, the tank220is integrated with the tank120of the radiator100.

The tank210has a receiving portion211and a discharge portion212. The receiving portion211receives the refrigerant circulating in the air conditioner. The receiving portion211is supplied with a low-temperature liquid-phase refrigerant after passing through an expansion valve (not shown) provided in the air conditioner. The receiving portion211is provided at a position near the upper end of the tank210. The discharge portion212discharges the refrigerant to the outside after being subjected to heat exchange. The gas phase refrigerant evaporated by heat exchange in the evaporator200is discharged to the outside from the discharge portion212, and then supplied to a compressor (not shown) of the air conditioner.

As shown inFIG.1, the internal space of the tank210is divided into three parts by separators S1and S2in the up-down direction. The receiving portion211is provided at a position above the separator S1on the upper side. The discharge portion212is provided at a position below the separator S2on the lower side.

The internal space of the tank220is divided into upper and lower parts by a separator (not shown). The position of the separator is lower than the separator S1and higher than the separator S2.

The tube230is a tubular member through which the refrigerant passes, and the evaporator200has the plural tubes230. Each tube230has an elongated straight shape and is arranged so as to extend in the horizontal direction. One end of the tube230is connected to the tank210, and the other end is connected to the tank220. Accordingly, the inside space of the tank210communicates with the inside space of the tank220through the tubes230.

The tubes230are arranged in the vertical direction, that is, along the longitudinal direction of the tank210. In this embodiment, each tube230is arranged adjacent to the tube130in the flow direction of air. That is, the same number of tubes230are provided as the number of tubes130, and the tubes230are arranged at the same height as the tubes130.

The refrigerant from the outside to the receiving portion211flows into the upper part of the internal space of the tank210above the separator S1. The refrigerant passes through the inside of the tube230arranged above the separator S1and flows into the upper part of the internal space of the tank220above the non-illustrated separator. After that, the refrigerant passes through the inside of the tube230arranged above the separator and below the separator S1and flows into the internal space of the tank210between the separator S1and the separator S2.

Further, after that, the refrigerant passes through the inside of the tube230arranged above the separator S2and below the separator in the tank220, and flows into the lower part of the internal space of the tank220below the separator. The refrigerant passes through the inside of the tube230arranged below the separator S2, flows into the lower part of the internal space of the tank210below the separator S2, and then is discharged to the outside from the discharge portion212.

When passing through the inside of each tube230as described above, the refrigerant is heated and evaporated by the air passing through the outside of the tube230, and changes from a liquid phase to a gas phase. The air has passed through the radiator100and the temperature is raised before heating the refrigerant. The temperature of the air is lowered since the heat of the air is absorbed by the refrigerant as passing outside the tube230.

The fin140(not shown inFIG.1) is arranged between the tubes230adjacent to each other in the vertical direction. The fin140is included in the radiator100described above. As shown inFIG.3, each fin140is arranged so as to extend from a position between the tubes130of the radiator100to a position between the tubes230of the evaporator200. That is, each fin140is shared by the radiator100and the evaporator200.

Therefore, the fins140and the tubes230are stacked so as to be alternately arranged in the vertical direction, in the evaporator200, as in the radiator100described with reference toFIG.2. The top of the wavy fin140is in contact with and brazed to the surface of the adjacent tube230in the vertical direction.

When the refrigerant passes through the inside of the tube230, the heat of the air is transferred to the refrigerant through the tube230and also to the refrigerant through the tube230and the fin140. That is, the contact area with the air is increased by the fin140, thereby the heat exchange between the air and the refrigerant is efficiently performed.

In the present embodiment, the heat of the cooling water passing through the inside of the tube130is further transferred to the refrigerant passing through the inside of the tube230by heat conduction through the fin140. In the evaporator200, not only the heat from the air but also the heat from the cooling water is recovered, so that the operating efficiency of the air conditioner is further improved.

As shown inFIG.1, a reinforcing plate300, which is a plate-shaped member, is arranged at a position on the upper side of the tube130,230located on the uppermost side. Further, a reinforcing plate400, which is a plate-shaped member, is arranged at a position on the lower side of the tube130,230located on the lowermost side. The reinforcing plate300,400is a metal plate provided to reinforce the tube130and the like to restrict their deformation. As shown inFIG.2, the fin140is also arranged between the reinforcing plate400and the tube130,230positioned on the lowermost side.

InFIG.1, the flow direction of air is represented by the x direction from the radiator100to the evaporator200, and the x-axis is set along the flow direction of air. Further, the y direction perpendicular to the x direction is set from the tank120to the tank110, that is, the longitudinal direction of the tube130, and the y-axis is set along the longitudinal direction of the tube130. Further, the z direction perpendicular to both the x direction and the y direction is set from the lower side to the upper side, that is, the longitudinal direction of the tank110, and the z-axis is along the longitudinal direction of the tank110. Hereinafter, the description will be given using the x direction, y direction, and z direction.

FIG.3shows one fin140and cross section of the tubes130and230arranged on the upper and lower sides of the fin140. As shown inFIG.3, each of the tubes130and230has a flat cross section extending in the x direction. A flow path FP1through which the cooling water passes is formed inside the tube130. An inner fin IF1is arranged in the flow path FP1. Similarly, a flow path FP2through which the refrigerant passes is formed inside the tube230. An inner fin IF2is arranged in the flow path FP2. A gap GP is formed between the tube130and the tube230arranged at the same height.

As shown inFIG.3, louvers141are formed on the fin140. The louver141is formed by cutting and bending a part of the fin140. Specifically, plural linear notches extending in the z direction are formed on the flat portion of the fin140so as to be arranged in the x direction, and then the area between the notches adjacent to each other is bent to form the louver141. The air passes through the gap formed in the vicinity of the louver141, such that the heat exchange with the air is performed more efficiently. As the shape of the louver141, the louver formed on the conventional fin can be adopted.

The specific configuration of the reinforcing plate400will be described. As described above, the reinforcing plate400is a plate-shaped member arranged at a position below the tubes130and230located on the lowermost side. The reinforcing plate400is formed as an elongated plate-shaped member, and is arranged so that the longitudinal direction of the reinforcing plate400is along the longitudinal direction of the tube130,230. As shown inFIGS.4and5, the reinforcing plate400has a flat portion410, a folded portion420, and a bent portion430.

The flat portion410is formed in a flat plate shape and occupies most of the reinforcing plate400. The normal direction of the flat portion410is along the z-axis.

The folded portion420is a substantially flat part formed so as to extend downward in the −z direction from each end of the flat portion410in the x direction. The bent portion430is formed by bending the central part of the flat portion410in the x direction so as to project downward, that is, in the −z direction. The bent portion430is formed so as to extend linearly along the longitudinal direction of the reinforcing plate400, the tube130, etc., that is, along the y direction.

The reinforcing plate300also has a bent portion (not shown) similar to the bent portion430. By forming such a bent portion, the rigidity of the reinforcing plate300,400is increased.

At the time of manufacturing the heat exchanger10, as shown inFIG.6, plural wires WR are wound around the heat exchanger10immediately before the brazing. The wire WR maintains the shape of the heat exchanger10before the brazing. The heat exchanger10is put into a furnace while the shape is maintained by the wire WR, and the whole including the brazing material is heated. As a result, each part of the heat exchanger10is brazed.

In the state ofFIG.6, the heat exchanger10is relatively strongly tightened by the wire WR. Therefore, if the rigidity of the reinforcing plate300,400is not sufficient, the reinforcing plate300,400is deformed by the tightening force from the wire WR, and the tubes130and fins140are deformed accordingly. In order to prevent such deformation, in the present embodiment, the bent portion430is formed on the reinforcing plate300,400to increase the rigidity thereof.

Even after the brazing is completed, the rigidity of the reinforcing plate300,400is maintained high by the bent portion430. As a result, the vibration resistance of the heat exchanger10is improved.

The air passing through the heat exchanger10in the x direction contains water vapor. Therefore, when the air is cooled as passing through the outside of the tube230, the water vapor contained in the air becomes condensed water and adheres to the surface of the tube230or the fin140. Further, the condensed water may become frost and adhere to the surface of the tube230or the fin140.

The condensed water and water generated by melting the frost are referred to “condensed water” as a whole. The condensed water moves downward by gravity along the surface of the tube230and the fin140. Eventually, the water reaches the upper surface of the reinforcing plate400located on the lower side and flows into the bent portion430.

As shown inFIGS.4,7, and8, the bent portion430has plural discharge holes440. The discharge hole440is a through hole formed so as to penetrate the reinforcing plate400. The condensed water flowing into the bent portion430from the upper side is discharged to the outside through any of the discharge holes440. That is, the discharge hole440is a hole for discharging the condensed water arriving from the upper side toward the lower side. The plural discharge holes440are formed as in the present embodiment, but the bent portion430may have only one discharge hole440.

The specific shape of the discharge hole440will be described. For convenience of explanation, an “upstream region431” represents a region of the bent portion430that is on the upstream side (the −x direction) in the air flow direction with respect to the lower end433of the bent portion430. Further, a “downstream region432” represents a region of the bent portion430that is on the downstream side (the x direction) in the air flow direction with respect to the lower end433.

FIG.7shows a cross section taken along a line VII-VII ofFIG.4. As shown inFIGS.4and7, the discharge hole440formed at this position penetrates the downstream region432of the bent portion430located on the downstream side in the x-direction relative to the lower end433. The discharge hole440positioned on the downstream side in the x-direction is referred to as “first discharge hole441”. In the present embodiment, the upper end of the first discharge hole441is located on the flat portion410. Further, the lower end of the first discharge hole441coincides with the lower end433of the bent portion430.

FIG.8shows a cross section taken along a line VIII-VIII ofFIG.4. As shown inFIGS.4and8, the discharge hole440formed at this position penetrates the upstream region431of the bent portion430located on the upstream side in the −x direction relative to the lower end433. The discharge hole440positioned on the upstream side in the −x direction is referred to as “second discharge hole442”. In the present embodiment, the upper end of the second discharge hole442is located on the flat portion410. Further, the lower end of the second discharge hole442coincides with the lower end433of the bent portion430.

As shown inFIG.4, in the reinforcing plate400according to the present embodiment, the first discharge hole441and the second discharge hole442are arranged alternately in the y direction in which the bent portion430extends.

The first discharge hole441and the like positioned in a manner deviated on the upstream side in the −x direction or the downstream side in the x direction may have various shapes.FIG.9shows a modification example of the first discharge hole441.

InFIG.9, the lower end of the first discharge hole441coincides with the lower end433of the bent portion430, as inFIG.7. However, the upper end of the first discharge hole441is positioned below the flat portion410.

In the cross section ofFIG.9, a part of the bent portion430excluding the discharge hole440can be expressed as a plate-shaped “rib” extending from the upper side toward the discharge hole440. The rib extending from the upper side toward the discharge hole440in the upstream region431is also referred to as “upstream rib451”. Similarly, the rib extending from the upper side toward the discharge hole440in the downstream region432is also referred to as “downstream rib452”.

InFIG.9, the upstream rib451has the height dimension L1along the z-axis. Further, the downstream rib452has the height dimension L2along the z-axis. InFIG.9, the first discharge hole441is formed so as to penetrate a part of the bent portion430deviated to the downstream side in the x direction. As a result, the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are different from each other, and the height dimension L1is larger than height dimension L2.

When each of the upstream rib451and the downstream rib452is defined as described above, in the configuration of the present embodiment shown inFIG.7, it can be said that the height dimension L2of the downstream rib452is zero. Further, in the configuration shown inFIG.8, it can be said that the height dimension L1of the upstream rib451is zero. In any case, the height dimension L1of the upstream rib451and the height dimension of the downstream rib452are different from each other. As described above, in the configuration in which “the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are different from each other”, the height dimension L1may be zero since the upstream rib451does not exist, or the height dimension L2may be zero since the downstream rib452does not exist.

FIG.10shows another modification example of the first discharge hole441, which is different from that ofFIG.9. In this modification, one end of the first discharge hole441is positioned as deviated to the upstream side in the −x direction with respect to the lower end433, that is, at a position in the middle of the upstream region431. Further, the other end of the first discharge hole441is located as deviated to the downstream side in the x-direction with respect to the lower end433, that is, in the middle of the downstream region432. The other end is located higher than the one end.

Therefore, even in the modification example ofFIG.10, the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are different from each other, and the height dimension L1is larger than the height dimension L2. As a result, the first discharge hole441is formed so as to penetrate a part of the bent portion430deviated to the downstream side in the x direction.

FIG.11shows a modification of the first discharge hole441, which is different from those ofFIGS.9and10. In this modification, the lower end of the first discharge hole441is positioned to the downstream side in the x-direction with respect to the lower end433, that is, at a position in the middle of the downstream region432. Further, the upper end of the first discharge hole441is located on the upper side of the lower end of the first discharge hole441and in the middle of the downstream region432.

Therefore, even in the modification example ofFIG.11, the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are different from each other, and the height dimension L1is larger than the height dimension L2. As a result, the first discharge hole441is formed so as to penetrate a part of the bent portion430that is deviated to the downstream side in the x direction.

In the configuration as in this modification, as shown inFIG.11, L1which is the “height dimension of the upstream rib451” corresponds to the protrusion amount of the bent portion430downward in the −z direction.

FIGS.9to11show the modifications in which the height dimension L1is larger than the height dimension L2. Instead of such modifications, the height dimension L2may be larger than the height dimension L1by inverting the configuration of each modification so as to be symmetrical with respect to the y-z plane. That is, similarly to the second discharge hole442shown inFIG.8, the discharge hole440may be formed so as to penetrate a part of the bent portion430that is deviated to the upstream side in the −x direction. In any case, the height dimension L1of the upstream rib451and the height dimension of the downstream rib452are different from each other.

The “first discharge hole441” can be redefined that the height dimension of the upstream rib451corresponding to one discharge hole440is larger than the height dimension of the downstream rib452corresponding to the one discharge hole440, among the plural discharge holes440. Each ofFIGS.9,10and11corresponds to the first discharge hole441.

Similarly, the “second discharge hole442” can be redefined that the height dimension of the upstream rib451corresponding to one discharge hole440is larger than the height dimension of the downstream rib452corresponding to the one discharge hole440, among the plural discharge holes440. If the configuration shown inFIGS.9,10and11is inverted so as to be symmetrical with respect to the y-z plane, the inverted configuration corresponds to the second discharge hole442. The shape of the second discharge hole442of the present embodiment may be configured according to such modifications.

In the reinforcing plate400according to the present embodiment, each discharge hole440is formed such that the height dimension L1of the upstream rib451and the height dimension of the downstream rib452are different from each other, as in each modification as described above. The advantages of such a configuration will be described with reference toFIG.12.

FIG.12shows a state (A) of a comparative example in which the condensed water WT stays on the upper surface of the reinforcing plate400. In this comparative example, the reinforcing plate400is generally flat, and the bent portion430is not formed. That is, the comparative example is defined by changing the reinforcing plate400of the present embodiment to entirely have the flat portion410. In this example, a through hole HL is formed so as to penetrate the reinforcing plate400in the up-down direction.

In the state (A) ofFIG.12, the reference character “LN” represents a boundary between the condensed water WT, the fin140existing on the back side of the paper surface, and the air, that is, a line to be a wet edge of the condensed water WT. In the following, the length of the wet edge of the condensed water WT with respect to the surrounding structure is also referred to as “wet edge length LN”. Further, the contact angle of the condensed water WT at the wet edge is referred to as “contact angle θ”. Further, the surface tension on the surface of the condensed water WT is referred to as “surface tension Y”.

A force is applied to the condensed water WT that wets the structure such as the fin140so as to be held on the surface of the structure due to the surface tension. If such a force is defined as “holding force”, the holding force can be calculated by the following (1).
(Holding force)=(Surface tensionY)×(Wet edge lengthLN)×cos θ  (1)

The z-axis component of the holding force calculated as described above acts on the condensed water WT as a force against gravity. In the state (A) ofFIG.12, most of the condensed water WT is present on the upper surface of the reinforcing plate400and widely wets the fin140in the vicinity thereof. In this case, as the wet edge length LN increases, a relatively large holding force acts on the condensed water WT. The arrow F3indicates the gravity acting on the condensed water WT. However, since the condensed water WT is held by the large holding force as described above, the condensed water WT is less likely to be discharged downward through the through hole HL.

FIG.12shows a state (B) according to another comparative example in which the condensed water WT stays on the upper surface of the reinforcing plate400. In this comparative example, the bent portion430is formed on the reinforcing plate400as in the present embodiment. However, in this comparative example, since the discharge hole440is formed so as to penetrate the center of the reinforcing plate400, the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are equal to each other.

In such a configuration, the condensed water WT moves downward due to gravity and flows into the bent portion430. After that, the condensed water WT is held between the upstream rib451and the downstream rib452facing each other.

The point P shown in the state (B) ofFIG.12indicates the wet edge of the condensed water WT extending along the depth direction of the paper surface. “F1” in the state (B) ofFIG.12is a force applied to the condensed water WT by surface tension along the surface of the reinforcing plate400, that is, the above-mentioned “holding force”. “F2” in the state (B) ofFIG.12is the z-axis component of F1which is the holding force in the z direction.

Even in the state (B) ofFIG.12, the gravity indicated by the arrow F3acts on the condensed water WT. In this case, the holding force acting on the condensed water WT is smaller than that in the state (A) ofFIG.12. However, the condensed water WT is in contact with both the upstream rib451and the downstream rib452, and is held by the holding force indicated by “F2” in the z direction from each of the upstream rib451and the downstream rib452. For this reason, the condensed water WT is held by a large holding force, so that the condensed water WT is less likely to be discharged downward through the discharge hole440.

FIG.12shows a state (C) in which the condensed water WT stays on the upper surface of the reinforcing plate400according to the present embodiment. The state (C) ofFIG.12schematically shows a cross section in the vicinity of the second discharge hole442shown inFIG.8.

In this case as well, as in the state (B) ofFIG.12, the condensed water WT moves downward due to gravity and flows into the bent portion430. However, in the present embodiment, the height dimension of the upstream rib451is zero, which is smaller than the height dimension of the downstream rib452. Therefore, most of the condensed water WT is in contact with the downstream rib452. Compared to the state (B) ofFIG.12in which the condensate water WT is held evenly by both the upstream rib451and the downstream rib452, the balance for retaining the condensed water WT is easily lost in the state (C) ofFIG.12. Therefore, the bridge of the condensed water WT is broken in a relatively short time, and the state (C) shifts to the state (D) shown inFIG.12.

In the state (D) ofFIG.12, the condensed water WT is in contact with only the downstream rib452. Therefore, the force F2, which is the z-axis component of the holding force, is reduced to half as compared with the state (B) ofFIG.12. Since the holding force applied to the condensed water WT becomes smaller, the condensed water WT moves downward due to the gravity indicated by the arrow F3, and is smoothly discharged to the outside from the second discharge hole442. Also in the first discharge hole441, the holding force is reduced to half as described above, so that the condensed water WT is smoothly discharged.

As described above, according to the configuration in which the discharge hole440is formed so that the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are different from each other, it is possible to sufficiently drain the condensed water. Such an effect can be achieved not only in the same configuration as that of the present embodiment but also in the modifications described with reference toFIGS.9to11.

FIG.19schematically shows a state (A) corresponding to the modification example shown inFIG.10, and illustrates a part of the bent portion430having the first discharge hole441as viewed in the x-direction. As shown inFIG.19, in this configuration, the height dimension (L1) of the upstream rib451and the height dimension (L2) of the downstream rib452are different from each other, in the entire range D0of the discharge hole440along the y direction (that is, the longitudinal direction of the tube130).

In contrast, in a state (B) ofFIG.19, the height dimension (L1) of the upstream rib451and the height dimension (L2) of the downstream rib452are different from each other only in a first range D1of the discharge hole440along the y direction. In the other range D2of the discharge hole440along the y direction, the height dimension (L2) of the upstream rib451and the height dimension (L2) of the downstream rib452are the same as each other. Even when the discharge hole440is formed so as to have such a shape, the holding force for holding the condensed water WT can be reduced, compared with the configuration in which the height dimension of the upstream rib451and the height dimension of the downstream rib452are the same in the entire range D0. Thus, the above-mentioned effect can be obtained.

As described above, the height dimension of the upstream rib451and the height dimension of the downstream rib452are different from each other in at least partially in the longitudinal direction of the tube130. Such a configuration can be applied to the present embodiment shown inFIGS.7and8, the modifications shown inFIGS.9to11, and a configuration in which the modification is inverted so as to be symmetrical with respect to the y-z plane (that is, a configuration of the second discharge hole442and its surroundings).

The first discharge hole441and the second discharge hole442are defined as follows. In the first discharge hole441, the height dimension of the upstream rib451corresponding to one discharge hole is larger than the height dimension of the downstream rib452corresponding to the one discharge hole at least partially in the longitudinal direction of the tube130. Further, in the second discharge hole442, the height dimension of the downstream rib452corresponding to one discharge hole is larger than the height dimension of the upstream rib451corresponding to the one discharge hole at least partially in the longitudinal direction of the tube130. As described above, in the reinforcing plate400according to the present embodiment, two types of holes including the first discharge hole441and the second discharge hole442are formed as the discharge holes440. Of these, the first discharge hole441makes it possible to discharge the condensed water more smoothly than the second discharge hole442.

This reason will be described. The arrow AR1shown inFIG.13indicates the flow of air through the heat exchanger10. Further, the arrow AR2shown inFIG.13indicates the flow of condensed water pushed out by the flow of air. As shown by the arrow AR2, the condensed water staying on the upper surface of the reinforcing plate400moves in the x direction by receiving the force due to the air flow, so-called “ram pressure”, and flows into the bent portion430. Since the first discharge hole441is widely open to the downstream side in the x-direction, the condensed water that has moved in the x-direction and reached the bent portion430retains a part of the momentum in the x-direction, and is discharged in the x direction through the first discharge hole441. Therefore, as compared with the second discharge hole442, the condensed water is discharged from the first discharge hole441more smoothly.

The arrow AR11shown inFIG.14indicates the flow of air passing through the lower side of the heat exchanger10, that is, further lower side of the reinforcing plate400. Such an air flow is generated, for example, when a shutter arranged on the upstream side of the heat exchanger10in the −x direction is closed, and air generated by traveling the vehicle or a fan flows to the downstream side from the outer peripheral portion of the shutter. The air indicated by the arrow AR11does not pass through the upper side of the reinforcing plate400, but only through the lower side.

It should be noted that a flow of air that passes only through the lower side of the reinforcing plate400may occur even when the shutter is not arranged on the upstream side of the heat exchanger10in the −x direction. For example, if a gap between the reinforcing plate400and the tube130is covered by a peripheral structure (not shown) on the upstream side in the −x direction, an air flow as indicated by the arrow AR11may occur.

When an air flow as indicated by the arrow AR11occurs, a negative pressure due to the air flow is generated in the vicinity of the bent portion430. The condensed water accumulated inside the bent portion430is drawn out from the first discharge hole441to the downstream side in the x-direction by the negative pressure, and is discharged to the outside. InFIG.13, the path through which the condensed water flows is indicated by the arrow AR12. In the present embodiment, due to the first discharge hole441, the condensed water can be discharged more smoothly.

InFIG.15, the dotted line DL1shows the magnitude of the holding force applied to the condensed water in the z direction in the state (B) ofFIG.12, where the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are equal to each other throughout the longitudinal direction of the tube130. Further, the height of the bar G1shown inFIG.15indicates the magnitude of gravity applied to the condensed water. The height of the bar G1is lower than that of the dotted line DL1. This indicates that in the state (B) representing the comparative example inFIG.12, the holding force is larger than the gravity, so that the condensed water is less likely to be discharged to the outside.

InFIG.15, the dotted line DL2shows the magnitude of the holding force applied to the condensed water in the z direction in the configuration according to the present embodiment, in which the height dimension L1of the upstream rib451and the height dimension L2of the downstream rib452are different from each other at least partially in the longitudinal direction of the tube130. As described with reference toFIG.12, the holding force applied to the condensed water in the configuration of the present embodiment is reduced to half, that is, the dotted line DL1, as compared with the state (B) ofFIG.12. As a result, in the configuration of the present embodiment, the holding force indicated by the dotted line DL2is smaller than the gravity indicated by the bar G1, so that the condensed water is smoothly discharged.

The bar G2shown inFIG.15is obtained by adding the bar OF to the bar G1. The bar OF schematically represents the force due to the air flow described with reference toFIG.13or the force due to the negative pressure described with reference toFIG.14, by converting into the force for discharging the condensed water. Therefore, the total height obtained by adding the bar OF to the bar G1corresponds to the force for discharging the condensed water to the outside in the configuration of the present embodiment. As shown inFIG.15, the force greatly exceeds the dotted line DL2which is the holding force. Therefore, in the present embodiment, the condensed water is discharged more smoothly.

In view of the discharge efficiency of condensed water, it seems better to make all the discharge holes440as the first discharge holes441. However, in the present embodiment, such a configuration is not adopted, and the discharge hole440includes both the first discharge hole441and the second discharge hole442. As shown inFIG.4, the first discharge hole441and the second discharge hole442are arranged alternately in the longitudinal direction of the tube130.

In such a configuration, if the reinforcing plate400is erroneously assembled at the time of assembling the heat exchanger10, specifically, if the reinforcing plate400is assembled in a state of being rotated 180 degrees around the z-axis from the state ofFIG.4, a part of the discharge holes440can function as the first discharge hole441. The “a part of the discharge hole440” means a discharge hole440that was planned to be a second discharge hole442when the reinforcing plate400was normally assembled.

It is preferable that the shape of the reinforcing plate400is symmetrical so as to be the same shape even when rotated 180 degrees around the z-axis, in order to achieve exactly the same discharge performance, even if the reinforcing plate400is erroneously assembled as described above.

The heat exchanger10according to the present embodiment includes the tube130and the tube230. The tubes130are arranged in the vertical direction, and correspond to the “first tube” in the present embodiment. The tubes230are arranged in the vertical direction at a position downstream of the tube130in the air flow direction, and correspond to the “second tube” in the present embodiment. As described above, the gap GP is formed between the tubes130and the tubes230adjacent to each other in the air flow direction. As shown inFIG.16, the bent portion430in the present embodiment is formed at a position directly below the gap GP formed between the tube130and the tube230.

In such a configuration, most of the condensed water generated on the surface of the tube130, the tube230, and the fin140is moved downward through the gap GP by gravity and flows into the bent portion430directly under the gap GP. After that, as described above, the condensed water is discharged to the outside from the discharge hole440. InFIG.16, the flow of condensed water moving downward through the gap GP as described above is indicated by the arrow AR3.

As described above, in the present embodiment, the bent portion430is located directly below the gap GP, so that the condensed water can be discharged more smoothly.

A second embodiment will be described. Hereinafter, only parts different from the first embodiment will be described, and description of parts common to the first embodiment will be omitted for brevity where appropriate.

The heat exchanger10according to the present embodiment does not include the radiator100of the first embodiment, and is composed of the evaporator200. That is, the heat exchanger10is configured as a single heat exchanger, not a composite heat exchanger. Therefore, as shown inFIG.17, the width dimension of the reinforcing plate400in the x direction is substantially the same as the width dimension of the tube230in the x direction. In this embodiment, there is no gap GP of the first embodiment.

The reinforcing plate400according to the present embodiment is formed as in the first embodiment, at the central part of the flat portion410in the x direction. Even in such a configuration, the same effect as that described in the first embodiment is obtained. As described above, the shape of the reinforcing plate400for improving the drainage property can be applied to not only the composite heat exchanger as in the first embodiment, but also a single heat exchanger having only one row of the tubes230arranged in the vertical direction.

A third embodiment will be described. Hereinafter, only parts different from the first embodiment will be described, and description of parts common to the first embodiment will be omitted for brevity where appropriate.

This embodiment differs from the first embodiment only in the arrangement of the discharge holes440formed in the reinforcing plate400. As shown inFIG.18, in the present embodiment, all the discharge holes440are formed as the first discharge hole441positioned as deviated to the downstream side in the x direction, and there is no second discharge hole442. The shape of each discharge hole440is the same as the shape of the first discharge hole441of the first embodiment described with reference toFIG.7. However, each discharge hole440may have the shape as shown in any ofFIGS.9,10, and11. At that time, a part or all of the discharge holes440may be shaped as in the example described with reference to the state (B) ofFIG.19. That is, the height dimension of the upstream rib451and the height dimension of the downstream rib452may be different from each other in a part in the longitudinal direction of the tube130.

As described above, in the present embodiment, all of the discharge holes440are formed such that the height dimension of the upstream rib451corresponding to one discharge hole440is higher than the height dimension of the downstream rib452corresponding to the one discharge hole440at least in part in the longitudinal direction of the tube130. With such a configuration, it is possible to facilitate the discharge of water from all the discharge holes440by the flow of air as described with reference toFIGS.13and14. The reinforcing plate400having such a configuration may be adopted in the second embodiment described above.

For example, when it is possible to prevent an error in the assembly direction of the reinforcing plate400by some mechanism, it is desirable to further facilitate the discharge of condensed water by configuring all the discharge holes440as the first discharge holes as in the present embodiment.

The present embodiment has been described above with reference to the specific examples. However, the present disclosure is not limited to those specific examples. Those specific examples that are appropriately modified in design by those skilled in the art are also encompassed in the scope of the present disclosure, as far as the modified specific examples have the features of the present disclosure. Each element included in each of the specific examples described above and the arrangement, condition, shape, and the like thereof are not limited to those illustrated, and can be changed as appropriate. The combinations of elements included in each of the above described specific examples can be appropriately modified as long as no technical inconsistency occurs.