JP3214318B2 - Outdoor heat exchanger for heat pump refrigeration cycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used in a heat pump refrigeration cycle, and is effective for use in an outdoor heat exchanger of a heat pump refrigeration cycle mounted on an electric vehicle.

[0002]

2. Description of the Related Art Conventionally, an outdoor heat exchanger used in a heat pump refrigeration cycle mounted on an electric vehicle is mounted in front of a vehicle. So-called "frosting" due to the adhesion and freezing of water and raindrops in the outdoor heat exchanger heat exchange (core)
It is easy to occur in the part. Therefore, there is a problem that the air permeability of the frosted portion is deteriorated, and the heat absorbing capacity of the heat exchange section is reduced, and as a result, the heating capacity is rapidly reduced.

Therefore, as a means for solving this problem,
The heat exchange part of the outdoor heat exchanger is divided into two parts, one is placed in front of the vehicle hit by the traveling wind, and the other is placed in a position that is hardly affected by the traveling wind. It is known that a rapid decrease in the heating capacity is prevented by maintaining the temperature.

[0004]

However, since the heat exchanging section is divided into two parts as described above and they are arranged at different places, a new problem of a reduction in space efficiency occurs. As is well known, the outdoor heat exchanger of the heat pump refrigeration cycle operates as a heat absorber (evaporator) when heating the vehicle interior, and operates as a heat generator (condenser) when cooling the vehicle interior. The phase change state of the refrigerant flowing through the inside is different between when heating the passenger compartment and when cooling the passenger compartment.

Therefore, if priority is given to the heat exchange (evaporation) efficiency during the heating of the vehicle interior, the heat exchange (condensation) efficiency during the cooling of the vehicle interior is reduced. On the other hand, if the heat exchange (condensation) efficiency at the time of vehicle interior cooling is prioritized, the heat exchange (evaporation) efficiency at the time of vehicle interior heating decreases. The present invention has been made in view of the above points, and in an outdoor heat exchanger used for a heat pump refrigeration cycle, heat can be efficiently exchanged even in both an endothermic operation and an exothermic operation state, and the space efficiency is reduced. It is an object of the present invention to prevent a sudden decrease in heating capacity due to frosting while preventing the heating.

[0006]

The present invention uses the following technical means to achieve the above object. According to the first aspect of the present invention, the plurality of heat exchange units (16a, 16b)
Are arranged in series along the flow direction of the external fluid with a predetermined gap (C) in a state where the refrigerant passages (2a, 2b) communicate with each other. Further, the cross-sectional area of the refrigerant passage of the heat exchange unit (16a) located on the upstream side is reduced by the heat exchange unit (1) on the downstream side.
6b) is smaller than the cross-sectional area of the refrigerant passage.

The heat exchanging sections (16a, 16a)
When b) is used as an evaporator, the refrigerant flows in from the upstream heat exchange section (16a), and when it is used as a condenser, the refrigerant flows in from the downstream heat exchange section (16b). It is characterized by the following. According to the second aspect of the present invention, a plurality of heat exchange portions (16a, 16b) are provided with a predetermined gap (C) in a state where the refrigerant passages (2a, 2b) are communicated with each other, and an external fluid is provided. Arrange in series along the flow direction. Furthermore, the sum total of the cross-sectional area of the hole of the tube (2a) communicating with any one of the auxiliary spaces (100a to 105a) of the heat exchange section (16a) located on the upstream side of the external fluid flow is equal to the external fluid. The auxiliary space (100b to 103) of the heat exchange section (16b) located downstream of the flow
b) communicating with any one of the tubes (2)
b) It is made smaller than the sum of the hole cross-sectional areas.

Then, the heat exchange sections (16a, 16a)
When b) is used as an evaporator, the refrigerant flows in from the upstream heat exchange section (16a), and when it is used as a condenser, the refrigerant flows in from the downstream heat exchange section (16b). It is characterized by the following. According to the third aspect of the present invention, in the heat exchanger according to the second aspect, the difference in the sum of the cross-sectional areas of the holes of the tubes (2a) communicating with the auxiliary spaces (100a to 105a) is different from the tubes (2a, 2b).

Next, the function and effect will be described. According to the first to third aspects of the present invention, the predetermined gap (C) is provided between the upstream heat exchange section (16a) and the downstream heat exchange section (16b). Even if the heat exchange part (16a) on the side is clogged, the heat exchange part (16b) on the downstream side
Heat can be exchanged by the external fluid flowing from the gap (C). Therefore, even if clogging is caused by frost formation, it is possible to prevent a rapid decrease in heating capacity.

Further, a plurality of heat exchange sections (16a, 16a) are provided.
b) are arranged in series along the air flow direction with a predetermined gap (C), so that a plurality of heat exchange sections (16a,
16b) They can be placed together in one place. Therefore, the space efficiency can be improved as compared with the case where the plurality of heat exchange sections (16a, 16b) are arranged at different locations.

In the heating operation, the evaporating pressure also drops together with the pressure drop in the refrigerant passage due to the pressure loss of the refrigerant flowing in the refrigerant passage, so that the plurality of heat exchange portions (16a, 16b) Of the refrigerant also decreases with the flow of the refrigerant. In other words, the refrigerant temperature decreases as it proceeds from the upstream side of the external fluid flow to the downstream side. Further, since the external fluid passing through the plurality of heat exchange sections (16a, 16b) is absorbed by the plurality of heat exchange sections (16a, 16b), the external fluid passes through the plurality of heat exchange sections (16a, 16b). The temperature of the external fluid drops as it proceeds from the upstream side to the downstream side.

Therefore, a plurality of heat exchange units (16a,
16b), the temperature of the external fluid passing through the plurality of heat exchangers (16a, 16b) and the temperature of the refrigerant flowing through the plurality of heat exchange sections (16a, 16b) decrease from the upstream side of the external fluid flow to the downstream side. From downstream to
The reduction in the temperature difference between the external fluid and the refrigerant can be suppressed. As a result, the heat exchange (heat absorption) efficiency of the heat exchanger can be improved.

Further, during the heating operation, the evaporation of the refrigerant proceeds as the refrigerant proceeds from the refrigerant flow path of the heat exchange section (16a) on the upstream side of the external fluid flow to the refrigerant flow path of the heat exchange section (16b) on the downstream side of the external fluid flow. Therefore, the volume gradually expands. However, since the refrigerant flows from the upstream refrigerant flow path having a small cross-sectional area of the refrigerant flow path to the downstream refrigerant flow path having a large cross-sectional area of the refrigerant flow path, a plurality of heat exchange parts (16a , 16b) can be suppressed. Therefore, a plurality of heat exchange units (16
Since the refrigerant can evaporate stably in a and 16b), the heat exchange (heat absorption) efficiency of the heat exchanger can be further improved.

Further, during the cooling operation, the plurality of heat exchange sections (16a, 16b) operate as condensers, so that the refrigerant is condensed and cooled, and its temperature is lowered together with the flow of the refrigerant. Therefore, the refrigerant temperature increases as the heat proceeds from the upstream heat exchange section (16a) to the downstream heat exchange section (16b). On the other hand, the temperature of the external fluid passing through the plurality of heat exchanging sections (16a, 16b) rises from the upstream side to the downstream side due to the heat of condensation from the refrigerant.

Therefore, a plurality of heat exchange sections (16a,
Both the temperature of the external fluid passing through 16b) and the temperature of the refrigerant flowing through the plurality of heat exchange sections (16a, 16b) are:
As the temperature increases from the upstream side of the external fluid flow to the downstream side, from the upstream side of the external fluid flow to the downstream side,
The reduction in the temperature difference between the external fluid and the refrigerant can be suppressed. As a result, the heat exchange (radiation) efficiency of the heat exchanger can be improved.

Further, during the cooling operation, the refrigerant gradually condenses as the refrigerant advances from the downstream refrigerant flow path to the upstream refrigerant flow path. However, since the refrigerant flows from the downstream refrigerant flow path having a large refrigerant flow path cross-sectional area toward the upstream refrigerant flow path having a small refrigerant flow path cross-sectional area, a plurality of heat exchange units (16a , 16b) can be suppressed. Therefore, a plurality of heat exchange parts (16a,
Since the refrigerant can be stably condensed in 16b), the heat exchange (radiation) efficiency of the heat exchanger can be further improved.

According to the third aspect of the present invention, the tubes (2a, 2a, 2a, 2a,
Since the cross-sectional area of the refrigerant passage can be easily changed by changing the number of b), the cross-sectional area of the refrigerant passage suitable for the phase state of the refrigerant can be obtained with a simple structure. Therefore, it is possible to improve the heat exchange efficiency of the heat exchanger while suppressing an increase in manufacturing cost.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; (Embodiment) FIG. 1 is a schematic diagram when the heat exchanger according to the present embodiment is used as an outdoor heat exchanger of a heat pump refrigeration cycle (hereinafter simply referred to as a refrigeration cycle) mounted on an electric vehicle. Is shown.

Reference numeral 15 denotes a compressor for compressing the refrigerant. The compressor 15 is a hermetic (volume) type compressor having a built-in electric motor for driving (not shown), and discharges the refrigerant in accordance with the rotation speed of the electric motor. The amount changes. The rotation speed of the electric motor is frequency-controlled by the inverter 22. 16 is an outdoor heat exchanger according to the present embodiment, which is usually
It is arranged in front of the engine room (see FIG. 7) of the electric vehicle which is apt to receive traveling wind. This outdoor heat exchanger 16
Has two heat exchange (core) sections for exchanging heat between the traveling wind and the refrigerant, and arranges one heat exchange section 16a on the upstream side of the traveling wind flow and the other heat exchange section 16b. Are arranged on the downstream side in series along the traveling wind flow. The details of the outdoor heat exchanger 16 will be described later.

Incidentally, reference numeral 23 denotes a cooling fan for promoting the flow of air passing through both heat exchange portions 15a and 16b of the outdoor heat exchanger 16. Reference numeral 2 denotes an air-conditioning casing forming an air flow path for guiding the air blown by the blower 3 into the vehicle interior. Inside the air-conditioning casing 2, an indoor evaporator 17 serving as air cooling means and an indoor condenser serving as air heating means are provided. 18 are arranged. The indoor evaporator 17 evaporates (vaporizes) the low-temperature and low-pressure mist refrigerant, thereby forming the indoor evaporator 17.
Is cooled, and the indoor condenser 18 heats the air passing through the indoor condenser 18 by condensing the high-temperature and high-pressure gas-phase refrigerant.

The first pressure reducing device 19 reduces the pressure of the refrigerant fed to the indoor evaporator 17 during the cooling operation and the dehumidifying (defrosting) operation. In this embodiment, a fixed-throttle capillary tube is used. Have been. Second decompression device 2
Numeral 0 depressurizes the refrigerant that is pressure-fed to the outdoor heat exchanger 16 during the heating operation. In the present embodiment, a fixed-throttle capillary tube is used.

Reference numeral 21 denotes an accumulator for temporarily storing excess refrigerant in the refrigeration cycle. The accumulator 21 is disposed on the suction side of the compressor 15 to prevent liquid refrigerant from being sucked into the compressor 15 (compression). (Prevents overcompression of the machine 15). In this embodiment, two accumulators 21 are provided. By the way, 3
Reference numeral 7 denotes an electric heater for assisting the heating capacity at the time of the maximum heating, and energizes the electric heater 37 to heat the air flowing in the air conditioning casing 2.

The refrigeration cycle switches between a cooling operation, a heating operation and a dehumidification (defrosting) operation by switching a circulation path of a refrigerant circulating in the refrigeration cycle. The circulation path switching means for switching the circulation path includes a four-way valve 31 disposed on the discharge side of the compressor 15, electromagnetic valves 32 and 33 for opening and closing the refrigerant flow path (piping) according to the operation state, and It comprises check valves 34 and 35 for regulating the flow direction of the refrigerant. Each component of the circulation path switching means is connected by a refrigerant pipe, and is arranged and configured as shown in FIG.

That is, the circulation path during the cooling operation is from the compressor 15 to the four-way valve 31, the check valve 34, the solenoid valve 32, the outdoor heat exchanger 16, the first pressure reducing device 19, the indoor evaporator 17, and the accumulator 21. , And reaches the compressor 15 again. During the heating operation, the circulation path from the compressor 15 passes through the four-way valve 31, the indoor condenser 18, the check valve 35, the second pressure reducing device 20, the outdoor heat exchanger 16, the electromagnetic valve 33, and the accumulator 21 again. The number reaches 15.

The circulation path during the dehumidification (defrosting) operation is from the compressor 15 to the four-way valve 31, the indoor condenser 18, the check valve 35, the second pressure reducing device 20, the electromagnetic valve 32, the outdoor heat exchanger 16, 1
The refrigerant reaches the compressor 15 again through the decompression device 19, the indoor evaporator 17, and the accumulator 21. next,
The outdoor heat exchanger 16 will be described with reference to FIGS.

FIG. 2 shows the outdoor heat exchanger 1 from the air flow upstream side.
6, and FIG. 3 is a right side view of FIG.
The heat exchange section 16a on the upstream side of the air flow and the heat exchange section 16b on the downstream side have substantially the same external structure except for the position of a separator provided in a header tank described later. Therefore, regarding the external structure, the heat exchange section 16a
Is described as an example. The subscript “b” in FIG.
2 shows the parts of the heat exchange unit 16b corresponding to FIG.

In FIG. 2, reference numeral 2a denotes a flat tube through which an aluminum refrigerant flows, which is integrally formed by extrusion or the like. As shown in FIG. 2, the plurality of flat tubes 2a are arranged so as to be parallel to each other.
Between adjacent flat tubes 2a, corrugated aluminum cooling fins 3a are brazed to the flat surfaces of the flat tubes 2a. The flat tubes 2a and 2b have the same hole cross-sectional area and outer dimensions.

A first header tank 4a made of aluminum, which communicates with the holes of the plurality of flat tubes 2a and distributes and collects the refrigerant, is brazed to one end of the flat tubes 2a. Is brazed to a second header tank 5a which communicates with the holes of the plurality of flat tubes 2a to distribute and collect the refrigerant. A pipe joint 6a for connecting an external pipe connected to the outdoor heat exchanger 16 is brazed to the first header tank 4a. The second header tank 5a of the heat exchange section 16a on the upstream side of the air and the second header tank 5b of the heat exchange section 16b on the downstream side of the air communicate with each other through the connection pipe 7.

The heat exchanging section 16a is composed of the flat tubes 2a and the cooling fins 3a brazed to them, as described above. Of the ends of the heat exchanging section 16a, the two header tanks 4a, 5a Are provided at both ends where no side plate 8 is provided as a reinforcing member for the heat exchange section 16a.
a is brazed to both header tanks 4a, 5a.
The heat exchange sections 16a and 16b are connected to both heat exchange sections 1
In a state where a predetermined gap C is provided between the side plates 6a and 16b, as shown in FIG.
a and 8b are assembled with bolts 10 via brackets 9. The gap C is 5 mm or more, and is about 5 mm in the present embodiment.

FIG. 4 is a schematic view of the outdoor heat exchanger 16 and shows a cross section of the header tank. As shown in FIG. 4, the inner space of both header tanks 4a and 5a is divided into a plurality by a plurality of separators 11a to form a plurality of auxiliary spaces 100a to 105a. Similarly, in the first and second header tanks 4b and 5b of the heat exchange section 16b on the downstream side of the air, a plurality of auxiliary spaces 100b to 103b are formed by the plurality of separators 11b.

Further, the number of auxiliary spaces of the air upstream heat exchange section 16a is larger than the number of auxiliary spaces of the air downstream heat exchange section 16b. Are three in each case and two in each of the header tanks 4b and 5b on the downstream side of the air. Therefore, the number of the flat tubes 2a communicating with any one of the auxiliary spaces 100a to 105a of the heat exchange unit 16a is as follows:
The number is smaller than the number of flat tubes 2b communicating with any one of the auxiliary spaces 100b to 103b of the heat exchange unit 16b. That is, the sum of the hole cross-sectional areas of the flat tubes 2a at the portion where the refrigerant in the in-phase state flows in the refrigerant flowing in the heat exchange section 16a is the flattening of the portion in the refrigerant flowing in the in-phase state in the refrigerant flowing in the heat exchange section 16b. It is smaller than the sum total of the hole cross-sectional areas of the tube 2b.

In other words, the plurality of flat tubes 2a and 2b in which the in-phase refrigerant flows form a refrigerant passage through which the in-phase refrigerant flows, and the refrigerant tubes located on the upstream side of the air flow. The cross-sectional area of the passage is smaller than the cross-sectional area of the refrigerant passage on the downstream side. Next, the operation of the present embodiment will be described.

First, regarding the refrigeration cycle shown in FIG.
This will be described for each operating state. (1) At the time of cooling operation The four-way valve 31 is switched so as to have a flow path indicated by a solid line in FIG. Then, the solenoid valve 32 opens, and the solenoid valve 33 closes. Thus, the refrigerant discharged from the compressor 15 flows through the four-way valve 31, the check valve 43, and the solenoid valve 32, from the heat exchange part 16b of the outdoor heat exchanger 16 to the heat exchange part 16a. The refrigerant condenses (dissipates heat) while flowing through the outdoor heat exchanger 16, and then becomes a low-temperature and low-pressure mist-like refrigerant in the first pressure reducing device 19. Then, it is evaporated (heat absorbed) in the indoor evaporator 17, and is sucked again into the compressor 15 through the accumulator 21. The flow of the refrigerant during the cooling operation is indicated by arrow C in FIG.
Indicated by

In the cooling operation, a part of the refrigerant discharged from the compressor 15 flows to the second pressure reducing device 20 side, bypassing the solenoid valve 32 and the outdoor heat exchanger 16. , There is almost no pressure difference between the two ends, and since the inlet side of the second decompression device 20 is a gas-phase refrigerant, the amount of refrigerant actually passing through the second decompression device 20 is very small. Therefore, the original cooling capacity is hardly impaired. (2) At the time of heating operation The four-way valve 31 is switched so as to have a flow path indicated by a broken line in FIG. Then, the solenoid valve 32 closes, and the solenoid valve 33 opens. Thereby, the refrigerant discharged from the compressor 15 is condensed (radiated) in the indoor condenser 18 through the four-way valve 31.
Then, it passes through the check valve 35 and becomes a low-temperature and low-pressure atomized refrigerant in the second pressure reducing device 20. Then, it evaporates (heat-absorbs) while flowing from the heat exchange section 16a of the outdoor heat exchanger 16 to the heat exchange section 16b, and is sucked into the compressor 15 again via the solenoid valve 33 and the accumulator 21. The refrigerant flow during the heating operation is indicated by an arrow H in FIG.

In this heating operation, the second pressure reducing device 2
Although a part of the refrigerant decompressed at 0 bypasses the outdoor heat exchanger 16 and the electromagnetic valve 33 and flows to the first pressure reducing device 19 side, there is almost no pressure difference between both ends of the first pressure reducing device 19 and Since the inlet side of the pressure reducing device 19 is a gas-phase refrigerant,
The amount of refrigerant actually flowing to the indoor evaporator 17 after passing through the first pressure reducing device 19 is very small. Therefore, the original heating capacity is hardly impaired. (3) At the time of dehumidification (defrosting) operation The four-way valve 31 is switched so as to form a flow path indicated by a broken line in FIG. Then, the solenoid valve 32 opens, and the solenoid valve 33 closes. Thereby, the refrigerant discharged from the compressor 15 is condensed (radiated) in the indoor condenser 18 through the four-way valve 31.
Then, while passing through the check valve 35 and the solenoid valve 32 and flowing from the heat exchange part 16b of the outdoor heat exchanger 16 to the heat exchange part 16a, the heat is condensed (dissipated). It becomes a mist refrigerant. Then, it is evaporated (heat absorbed) in the indoor evaporator 17, and is sucked again into the compressor 15 through the accumulator 21. The flow of the refrigerant during the heating operation is indicated by an arrow D in FIG.
Indicated by

In this dehumidifying (defrosting) operation, the indoor condenser 1
A part of the refrigerant flowing out of the second decompression device 20 bypasses the electromagnetic valve 32 and the outdoor heat exchanger 16 and flows to the second decompression device 20 side. The amount of the refrigerant passing through the pressure reducing device 20 is very small.
Therefore, the original dehumidifying ability is hardly impaired. Next, the refrigerant flow in the outdoor heat exchanger 16 will be described with reference to FIG.

In FIG. 4, during the cooling or dehumidifying operation, the refrigerant flows from the pipe joint 6b of the heat exchange section 16b located downstream of the air flow to the auxiliary space 100b of the first header tank 3b, as indicated by the solid arrow. Flows into. Then, the air flows into the plurality of flat tubes 2b communicating with the auxiliary space 100b, and flows into the auxiliary space 10 of the second header tank 5b.
1b. Thereafter, the air flows into the auxiliary space 102b and the auxiliary space 103b via the flat tube 2b, and flows into the auxiliary space 100a of the heat exchange section 16a located on the upstream side of the air flow via the connection pipe 7.

Thereafter, the refrigerant flows through the auxiliary tube 102a through the flat tube 2a similarly to the flow of the refrigerant in the heat exchange section 16b.
a, auxiliary space 103a, auxiliary space 104a, auxiliary space 1
05a flows out of the flow pipe joint 6a and flows to the first pressure reducing device 19. During heating, as indicated by the dashed arrow, the flow is in the reverse direction during cooling or dehumidifying operation.

Next, the features of the present invention will be described. When the outside air temperature is low during a heating operation or the like, frost formation occurs due to the adhesion and freezing of moisture and raindrops in the air in the heat exchange section 16a of the outdoor heat exchanger 16 located upstream of the air flow. Part 1
The cooling fin 3a of 6a is clogged. However, as described above, the upstream heat exchange section 16a and the downstream heat exchange section 1
6b, the heat exchange portion 16b exchanges heat with air flowing from the gap C even when the cooling fins 3a of the heat exchange portion 16a are clogged. be able to. Therefore, even if the cooling fins 3a are clogged due to frost formation, it is possible to prevent a sharp decrease in the heating capacity.

Further, since both heat exchange portions 16a and 16b are arranged in series along the direction of air flow with a predetermined gap C, both heat exchange portions 16a and 16b are collectively arranged at the front portion of the vehicle. can do. Therefore, both heat exchange units 1
Space efficiency can be improved as compared with the case where the 6a and 16b are arranged at different places. In addition, since the outdoor heat exchanger 16 is mounted on the vehicle in a state where the two heat exchange portions 16a and 16b are integrally mounted by the bracket 9, the number of components such as mounting components can be reduced. The assemblability can be improved.

During the heating operation, the pressure loss of the refrigerant flowing in the refrigerant passage causes the refrigerant passage (flat tube)
Since the evaporating pressure also drops with the pressure drop in the inside, the refrigerant temperature in both heat exchange sections 16a and 16b also drops with the flow of the refrigerant. That is, the refrigerant temperature decreases as it proceeds from the upstream side to the downstream side of the air flow. In addition, both heat exchange units 1
The air passing through 6a, 16b passes through both heat exchange sections 16a, 1b.
Since the heat is absorbed at 6b, the temperature of the air passing through the heat exchange sections 16a and 16b falls as it goes from the upstream side to the downstream side.

Therefore, as shown in FIG. 5, both the temperature of the air passing through the heat exchange sections 16a and 16b and the temperature of the refrigerant flowing through the heat exchange sections 16a and 16b are changed from the upstream side to the downstream side as shown in FIG. Since the temperature decreases as the air travels, the reduction in the temperature difference between the air and the refrigerant can be suppressed from the upstream side to the downstream side of the air flow. As a result, the heat exchange (heat absorption) efficiency of the outdoor heat exchanger 16 can be improved.

In the heating operation, as the refrigerant evaporates as it proceeds from the upstream refrigerant flow path to the downstream refrigerant flow path, its volume is gradually expanded. However, since the refrigerant flows from the upstream refrigerant flow path having a small cross-sectional area of the refrigerant flow path to the downstream refrigerant flow path having a large cross-sectional area of the refrigerant flow path,
It is possible to suppress an increase in (evaporation) pressure in the heat exchange sections 16a and 16b due to the expansion of the volume. Therefore, the refrigerant can stably evaporate in the heat exchange sections 16a and 16b, so that the heat exchange (heat absorption) efficiency of the outdoor heat exchanger 16 can be further improved.

In the cooling operation, both heat exchange sections 16
Since a and 16b operate as radiators, the refrigerant condenses,
It is cooled and its temperature decreases with the flow of the refrigerant. Therefore, the heat exchange unit 16a on the upstream side is connected to the heat exchange unit 1 on the downstream side.
The refrigerant temperature rises as it goes to 6b. On the other hand, the temperature of the air passing through both heat exchange sections 16a and 16b increases from the upstream side to the downstream side due to the heat of condensation from the refrigerant.

Therefore, as shown in FIG. 6, both the temperature of the air passing through the heat exchange sections 16a and 16b and the temperature of the refrigerant flowing through the heat exchange sections 16a and 16b go from the upstream side to the downstream side of the air flow. As the temperature rises, the reduction in the temperature difference between the air and the refrigerant from the upstream side to the downstream side of the air flow can be suppressed. As a result, the heat exchange (radiation) efficiency of the outdoor heat exchanger 16 can be improved.

In the cooling operation, the refrigerant gradually condenses as it proceeds from the downstream refrigerant flow path to the upstream refrigerant flow path. However, since the refrigerant flows from the downstream refrigerant flow path having a large refrigerant flow path cross-sectional area toward the upstream refrigerant flow path having a small refrigerant flow path cross-sectional area,
It is possible to suppress a (condensation) pressure drop in both heat exchange units 16a and 16b due to a reduction in volume. Therefore, since the refrigerant can be stably condensed in the heat exchange sections 16a and 16b, the heat exchange (radiation) efficiency of the outdoor heat exchanger 16 can be further improved.

Further, the sectional area of the refrigerant passage can be changed by changing either the arrangement position or the number of the separators 11a, 11b. Can do it. Therefore, it is possible to improve the heat exchange efficiency of the outdoor heat exchanger 16 while suppressing an increase in manufacturing cost. Also, since the components of the upstream and downstream heat exchange units can be shared,
An increase in manufacturing costs can be further suppressed.

Incidentally, the outdoor heat exchanger according to the present invention is not limited to an electric vehicle, but may be used for a room air conditioner for home use. In the above embodiment,
Although the refrigerant passage cross-sectional areas (specifically, the number of the flat tubes 2a and 2b) in the same heat exchange section are equalized, the present invention can be implemented even if the refrigerant passage cross-sectional area is changed in the same heat exchange section. Can be.

In the above embodiment, the refrigerant passage meanders in the heat exchange section. However, the present invention can be applied to a so-called all-pass type heat exchanger in which the refrigerant flows in one direction in parallel. . Further, the refrigerant passage is not limited to a plurality of parallel flat tubes as in the above-described embodiment. For example, the present invention is also applied to a so-called serpent type heat exchanger formed by meandering one flat tube. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a heat pump refrigeration cycle using a heat exchanger according to the present embodiment.

FIG. 2 is a front view of the heat exchanger according to the embodiment.

FIG. 3 is a right side view of FIG. 2;

FIG. 4 is a schematic diagram of a heat exchanger according to the present embodiment.

FIG. 5 is an explanatory diagram showing a relationship between an air temperature and a refrigerant temperature during a heating operation.

FIG. 6 is an explanatory diagram showing a relationship between an air temperature and a refrigerant temperature during a cooling operation.

FIG. 7 is a schematic test diagram when the heat exchanger according to the present embodiment is mounted on a vehicle.

[Explanation of symbols]

2a, 2b ... flat tube (tube), 3a, 3b ...
Cooling fins, 4a, 4b: first header tank, 5a, 5
b: second header tank, 6a, 6b: piping joint,
7 Connection pipe, 8a, 8b Side plate, 9 Bracket, 11a, 11b Separator, 16a, 16b
... heat exchange unit, 16 ... outdoor heat exchanger, 100a-105
a, 100b to 103b ... auxiliary space.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-84395 (JP, A) JP-A-4-131665 (JP, A) JP-A-63-69957 (JP, U) (58) Survey Field (Int. Cl. ⁷ , DB name) F25B 39/00

Claims (3)

(57) [Claims] 1. A plurality of heat exchange parts (16a, 16b) having a refrigerant passage (2a, 2b) through which a refrigerant flows, and exchanging heat between an external fluid and the refrigerant. The portions (16a, 16b) are arranged in series along the flow direction of the external fluid with a predetermined gap (C) in a state where the refrigerant passages (2a, 2b) communicate with each other. When the heat exchange sections (16a, 16b) are used as evaporators, a refrigerant flows from the heat exchange section (16a) on the upstream side of the external fluid flow, and the plurality of heat exchange sections (16a, 16b) are used. ) Is used as a condenser, a refrigerant flows in from the heat exchange section (16b) on the downstream side of the external fluid flow, and further, a refrigerant passage of the heat exchange section (16a) located on the upstream side of the external fluid flow The cross-sectional area is located on the downstream side of the external fluid flow. An outdoor heat exchanger for a heat pump refrigeration cycle, wherein the outdoor heat exchanger is smaller than a refrigerant passage cross-sectional area of the heat exchange section (16b). 2. A plurality of heat exchanging units, each having a refrigerant passage made up of a plurality of tubes (2a, 2b) arranged in parallel with each other and flowing heat between an external fluid and the refrigerant. (16a, 16b); a header tank (4a, 4b, 5a, 5b) provided at an end of a plurality of tubes (2a, 2b) of the plurality of heat exchange sections (16a, 16b); A plurality of auxiliary spaces (100a to 105) are arranged in the header tanks (4a, 4b, 5a, 5b) and partition the space inside the header tanks (4a, 4b, 5a, 5b).
a, 100b to 103b) (11)
a, 11b), the plurality of heat exchange portions (16a, 16b) having a predetermined gap (C) in a state where the refrigerant passages (2a, 2b) communicate with each other, and The auxiliary spaces (100a to 105a, 100b to 103) are arranged in series along the flow direction of the fluid.
b) a case in which a predetermined number of the tubes (2a, 2b) communicate with a predetermined number of the tubes to distribute and assemble the refrigerant, and the plurality of heat exchange units (16a, 16b) are used as evaporators. In the case where a refrigerant flows from the heat exchange section (16a) on the upstream side of the external fluid flow and the plurality of heat exchange sections (16a, 16b) are used as condensers, The tube that allows a refrigerant to flow from the heat exchange unit (16b) and further communicates with any one of the auxiliary spaces (100a to 105a) of the heat exchange unit (16a) located on the upstream side of the external fluid flow. The sum total of the hole cross-sectional areas of (2a) is the sum of the auxiliary spaces (100b to 103b) of the heat exchange unit (16b) located downstream of the external fluid flow.
The outdoor heat exchanger for a heat pump type refrigeration cycle, wherein the total sum of the hole cross-sectional areas of the tubes (2b) communicating with any one of the tubes is small. 3. The difference in the sum of the hole cross-sectional areas of the tubes (2a) communicating with the auxiliary spaces (100a to 105a) is constituted by the difference in the number of tubes (2a, 2b). The outdoor heat exchanger for a heat pump refrigeration cycle according to claim 2.