JP2013178033A - Heat exchanger and vehicle heat pump air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger capable of avoiding stop of heating operation caused by frost formation on an external heat exchanger, when cooling and heating can be performed only by a heat pump circuit, by applying a heat pump air conditioner to a vehicle air conditioner.SOLUTION: A heat exchanger 3 is installed as an external heat exchanger, in a vehicle heat pump air conditioner with a compressor, the external heat exchanger, an expansion valve and an internal heat exchanger provided in a refrigerant circuit. The heat exchanger includes a plurality of tubes 31 juxtaposed in a longitudinal direction and allowing a refrigerant to flow, and fins 32 arranged in a lateral direction between the tubes 31. A coat layer having water repellent performance is provided on at least upper surfaces of the fins 32 or the tubes 31.

Description

  The present invention relates to a heat exchanger suitable for mounting as an external heat exchanger in an electric vehicle and a vehicle heat pump air conditioner equipped with the heat exchanger.

For example, a vehicle air conditioner for an electric vehicle that does not include a prime mover such as a gasoline engine, a diesel engine, or a gas engine has been put to practical use as shown in FIG.
That is, as shown in FIG. 9, the vehicle air conditioner includes a refrigerant circuit 100 and a hot water circuit 110. The refrigerant circuit 100 includes a compressor 101, a condenser (external heat exchanger, so-called outdoor unit) 103, an expansion valve 104, and an evaporator (internal heat exchanger, so-called indoor unit) 105 in this order. In the refrigerant circuit 100. The hot water circuit 110 includes a reservoir tank 111, a hot water pump 112, a hot water PTC heater 113, and a heater core 114 in this order. A blower 121 that blows air from the back of the evaporator 105 and the heater core 114 is provided as an indoor unit in the vehicle interior.

  During the cooling operation, the operation of the hot water circuit 110 is stopped, the compressor 101 is operated, and the compressor 101, the condenser (outdoor unit) 103, the expansion valve 104, the evaporator (indoor unit) in the refrigerant circuit 100. The refrigerant is circulated in the order of 105. As a result, the refrigerant compressed to high temperature and high pressure by the compressor 101 releases heat in the condenser 103 and is cooled and condensed. The condensed refrigerant is cooled by adiabatic expansion at the expansion valve 104, and then cooled by taking away the heat of the air blown from the blower 121 in the evaporator 105. Proceed to 101. The passenger compartment is cooled by the circulation (refrigeration cycle) of the refrigerant.

  During the heating operation, the refrigerant circuit 100 is stopped, the hot water pump 112 is operated, and the water is circulated in the order of the reservoir tank 111, the hot water pump 112, the hot water PTC heater 113, and the heater core 114 in the hot water circuit 110. As a result, water is warmed in the hot water PTC heater 113 and sent to the heater core 114, and the air blown from the blower 121 is heated in the heater core 114. . The interior of the vehicle is heated by such warm water circulation (heat pump cycle).

In addition, the reason why the hot water PTC heater 113 is used as a heat source at the time of heating is that in the case of an electric vehicle that does not include a prime mover such as a gasoline engine, a diesel engine, or a gas engine, the exhaust heat of the engine cannot be used. Instead, a hot water PTC heater is used.
Moreover, in such a device configuration, as a cooling device that cools a large capacity motor / generator (motor generator, hereinafter simply referred to as a motor) 130 and a battery in a battery case (not shown) mounted on an electric vehicle. A water-cooled cooling circuit 140 is provided. The water-cooled cooling circuit 140 includes a reservoir tank 141, a radiator (heat radiator) 142, and a pump 143 in this order, and a motor 130 and an illustration are provided in a cooling water flow path between the cold water pump 143 and the reservoir tank 141. A battery case is provided.

  The radiator 142 is cooled by the cooling fan 150 together with the condenser 103 of the refrigerant circuit 100 using the outside air. As a result, the cooling water radiated and cooled by the radiator 142 is sent to the motor 130 and the battery case to cool the motor 130 and the battery in the battery case. The cooling water heated by this heat exchange during cooling proceeds to the radiator 142 again and is cooled.

However, since the hot water PTC heater 113 is an electric heater that uses electric power, in the case of an electric vehicle, the charging electric energy of the battery is reduced by the amount of electric power consumed by the hot water PTC heater 113. For this reason, when heating operation is performed, it becomes a subject that the cruising range of a vehicle falls.
In addition, two systems of a refrigerant circuit (refrigeration cycle) 100 used during cooling and a hot water circuit (hot water cycle) 110 used during heating are required as an air conditioner, resulting in high costs.

In addition, the motor and the battery are cooled by a water cooling method, and the battery to be cooled (particularly, a lithium ion battery) has a potential heat generation risk for water, so an alternative cooling method that does not use water is desirable.
By the way, the heat pump type air conditioner can switch between a cooling operation and a heating operation, and is widely used as an air conditioner for home use or business use (so-called heat pump air conditioner).

However, when the heating operation is started when the outside air temperature is extremely low (for example, −10 ° C. or less), the heat exchange part of the evaporator, which is an external heat exchanger, is frosted and frozen (frosted). Not only does the heating capacity decrease, but it may not be able to operate continuously in extreme cases.
In a building air conditioner, when such frosting or icing occurs in an external heat exchanger, the defrosting operation is performed in which the ventilation of the indoor unit is stopped and heating and reverse cycle operation (ie, refrigeration cycle operation) are performed. It is possible to continue the heating operation by performing defrosting by intermittently performing heating (defrost operation) by flowing a high-temperature refrigerant through the frozen evaporator (external heat exchanger). .

  For example, Patent Document 1 does not relate to a vehicle air conditioner, but performs a normal operation of heating water flowing in a water circuit and a defrosting operation that is a reverse cycle of the normal operation using a circulating refrigerant. A heat pump device is described. The outdoor unit of the heat pump device includes a circuit that bypasses a part of the refrigerant discharged from the compressor during the defrosting operation, and the control device connects the valve provided with the bypass circuit to the water heat exchanger. When this valve is opened during defrosting operation by controlling opening and closing based on each water temperature at the water inlet and water outlet, the third circuit of the bypass circuit is based on each refrigerant temperature at the refrigerant inlet and refrigerant outlet of the water heat exchanger. Adjust the opening of the expansion valve. Thereby, it is supposed that a defrosting operation can be carried out with high efficiency using a water heat exchanger.

  Patent Document 2 describes a technique for preventing condensation by causing a corrugated fin to incline laterally and causing water droplets on the fin to flow down in an evaporator that is a heat exchanger provided as an outdoor unit. Yes.

International Publication No. 2011/092802 Japanese Utility Model Publication No.59-480176

By the way, although it is not described in Patent Document 1 that it is applied to a vehicle air conditioner, a heat pump type air conditioner is also applied to a vehicle air conditioner, and the refrigerant flow direction is reversed using a refrigeration cycle. As a heat pump cycle, an air conditioner can be realized with only one circuit.
However, in the case of a vehicle air conditioner, there is a possibility that frost formation has occurred in the heat exchanger on the outside of the vehicle at the time of start-up in severe cold. In the case of a heat pump type air conditioner, when frost formation occurs, it can be defrosted by performing a defrosting operation. However, for this defrosting, how to recognize that frost formation has occurred and that the defrosting has been completed by the defrosting operation, and appropriately performing the defrosting operation becomes a problem. .

Therefore, there is a demand for a heat exchanger structure in which frost formation hardly occurs.
In this regard, the technique of Patent Document 2 is thought to be effective in preventing frost formation because the fin is tilted laterally and water is dripped, but when the fin is tilted laterally, water attached to the side portion of the fin It may remain due to capillary action and cause frost formation.
The present invention was devised in view of such problems, and even when a heat pump type air conditioner is applied to a vehicle air conditioner of an electric vehicle so that cooling and heating can be carried out only by a heat pump circuit, external heat can be applied. It aims at providing the heat exchanger which can avoid the heating operation stop by the frost formation to an exchanger.

  (1) In order to achieve the above object, a heat exchanger according to the present invention is a vehicle heat pump air conditioner having a compressor, an external heat exchanger, an expansion valve, and an internal heat exchanger in a refrigerant circuit. A heat exchanger equipped as the external heat exchanger, comprising a plurality of tubes arranged in a longitudinal direction and through which refrigerant flows, and fins disposed laterally between the tubes, A coating layer having water repellency is provided on at least one surface of the fin or the tube.

(2) It is preferable that the fin or the tube is inclined rearward or forwardly toward the outside air inflow direction.
(3) It is preferable that the fin or the tube is cut to form a bent piece portion, and a hole is formed by forming the bent piece portion.
(4) In this case, it is preferable that the fin or the tube is inclined backward toward the outside air inflow direction, and the bent piece portion is inclined backward toward the outside air inflow direction.

(5) The vehicle heat pump air conditioner according to the present invention is a vehicle heat pump air conditioner having a compressor, an external heat exchanger, an expansion valve, and an internal heat exchanger in a refrigerant circuit, The heat exchanger according to any one of claims 1 to 4 is used as the external heat exchanger.
(6) It is preferable that a bypass channel is provided between the compressor and the external heat exchanger for supplying high-pressure refrigerant from the compressor to the external heat exchanger during a defrosting operation.

According to the heat exchanger of the present invention, due to the water-repellent coating layer, water hardly adheres to the fin or tube surface, frost formation on the fin surface hardly occurs, and icing on the fin hardly occurs.
Also, even if water adheres to the surface of the fin or tube due to the back or front inclination of the fin or tube, it will drop quickly, so frosting on the surface of the fin is less likely to occur. Freezing is unlikely to occur. Since the contact area with the incoming outside air is increased, heat exchange performance is also improved.

In addition, the formation of the bent piece and the hole allows water droplets or the like on the surface of the fin or tube to be quickly dropped by the hole, and also from this point, frosting on the surface of the fin or tube hardly occurs. Freezing is unlikely to occur on the surface. Also in this case, the heat exchange performance is improved because the contact area with the outside air entering is increased.
Therefore, when applied to an external heat exchanger of a heat pump air conditioner for a vehicle such as an electric vehicle, an air conditioner with a countermeasure against frost formation can be realized at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the heat pump type | formula air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention, Comprising: (a) shows the state at the time of heating operation, (b) shows the state at the time of cooling operation. It is a front view which shows the structure of the external heat exchanger of the heat pump type | formula air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention. It is a perspective view showing the 1st example of the principal part composition of the external heat exchanger of the heat pump type air conditioner for vehicles of the electric car concerning one embodiment of the present invention. It is a perspective view which shows the 2nd example of the principal part structure of the external heat exchanger of the heat pump air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention. It is sectional drawing which shows the 1st example of the principal part structure of the external heat exchanger of the heat pump type | formula air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention, and its modification, (a) shows a 1st example. , (B) shows a modification thereof. It is sectional drawing which shows the 3rd example of the principal part structure of the external heat exchanger of the heat pump air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention, and its modification, (a) shows a 3rd example. , (B) shows a modification thereof. It is sectional drawing which shows the 4th example of the principal part structure of the external heat exchanger of the heat pump type | formula air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention, and its modification, (a) shows a 4th example. , (B) shows a modification thereof. It is a flowchart explaining the operating method of the heat pump type | formula air conditioner for vehicles of the electric vehicle concerning one Embodiment of this invention. It is a block diagram of the heat pump type air conditioner for vehicles concerning a background art.

Hereinafter, the heat pump type air conditioner for vehicles concerning an embodiment of the invention is explained with a drawing.
1 is a diagram showing a configuration of a vehicle heat pump air conditioner according to the present embodiment, FIGS. 2 to 7 are diagrams showing a configuration of an external heat exchanger of the vehicle heat pump air conditioner according to the present embodiment, and FIG. These are figures explaining the operating method of the heat pump type air conditioner for vehicles concerning this embodiment. This will be described in order with reference to the drawings. In addition, the vehicle concerning this embodiment shall be an electric vehicle provided with the battery connected to the motor for driving and the motor for driving.

First, a heat pump type air conditioner for a vehicle according to the present embodiment (hereinafter also referred to as a car air conditioner) will be described.
As shown in FIGS. 1A and 1B, this car air conditioner includes a compressor 1, a switching valve 2, an external heat exchanger (outdoor unit) 3, an expansion valve 4, an internal heat exchanger ( Indoor unit) 5 are provided in the refrigerant circuit 10 in this order. An accumulator 6 is attached to the compressor 1 so that the discharge pressure of the compressor 1 is stabilized. The internal heat exchanger 5 is provided with a fan 5a to form an indoor unit, and the vehicle internal air (inside air) or outside air (outside air) is passed through the internal heat exchanger 5 to be cooled or heated to It is designed to blow air indoors. Further, the external heat exchanger 3 is provided with a fan 7 for introducing outside air.

  In order to automatically control each part of the car air conditioner, an air conditioner ECU (Electric Control Unit) 50 is provided as a control device, which is an LSI device in which a microprocessor, ROM, RAM, etc. are integrated. For example, during the automatic operation of the air conditioner, the air conditioner ECU 50 automatically controls the switching valve 2 based on the detected values of the set temperature, the inside air temperature (the temperature inside the vehicle interior), and the outside air temperature. Each part is controlled also based on the command information of the operation switch.

  The refrigerant circuit 10 includes a flow path 11 between the compressor 1 and the switching valve 2, a flow path 12 between the switching valve 2 and the external heat exchanger 3, and the external heat exchanger 3 and the expansion valve 4. A flow path 13 between the expansion valve 4 and the internal heat exchanger 5, a flow path 15 between the internal heat exchanger 5 and the compressor 1, a switching valve 2 and an accumulator 6. And a flow path 17 between the accumulator 6 and the compressor 1.

  Further, the flow path 15 between the internal heat exchanger 5 and the compressor 1 and the flow path 13 between the expansion valve 4 and the external heat exchanger 3 are connected, and the expansion valve 4 and the internal heat exchanger 5 are connected. The bypass flow path 19 which comprises a defrost operation circuit is interposed so that it may detour. An opening / closing valve 20 is provided on the internal heat exchanger 5 side of the flow path 15, and an opening / closing valve 21 is provided on the bypass flow path 19 side. For the defrosting operation, the refrigerant sent from the downstream side of the compressor 1 to the external heat exchanger 3 has a relatively high temperature and does not require a large flow rate refrigerant. Therefore, a relatively narrow gutter can be applied to the bypass channel 19 as compared with the other channels 11 to 17 of the refrigerant circuit 10, which contributes to weight reduction and cost reduction.

  During the heating operation, when the on-off valve 20 is closed and the on-off valve 21 is opened, a part of the refrigerant that has been compressed by the compressor 11 and has become high temperature and high pressure flows into the external heat exchanger 3 through the bypass flow path 19, It becomes a defrost operation which can heat the heat exchanger 3 and defrost. Further, at the time of heating operation or cooling operation, the on-off valve 20 is opened and the on-off valve 21 is closed. These switching controls are performed by the air conditioner ECU 50 based on the outside air temperature or the difference between the inlet refrigerant temperature and the outlet refrigerant temperature of the external heat exchanger 3.

That is, the air conditioner ECU 50 detects the outside air temperature detected at this time by an outside air temperature sensor (outside air temperature detecting means) (not shown) after starting the vehicle, or the history of the outside air temperature detected at the nearest predetermined time before starting or When the outside air temperature based on the average value is equal to or lower than a preset reference temperature, the defrosting operation is started assuming that the defrosting operation start condition is satisfied.
Usually, when the outside air temperature falls to −10 ° C. or lower, it can be estimated that the external heat exchanger 3 has frost formation, and the reference temperature can be set to −10 ° C., for example.

The refrigerant inlet 3A of the external heat exchanger 3 is provided with a first temperature sensor (first refrigerant temperature detecting means) 41 for detecting the temperature of the refrigerant passing through the refrigerant inlet 3A (refrigerant inlet temperature), and partial heat exchange is performed. A second temperature sensor (second refrigerant temperature detecting means) 42 for detecting the temperature of the refrigerant passing through the refrigerant outlet 3B (refrigerant outlet temperature) by the refrigerant of the vessel 3 is provided at the port 3B.
During the defrosting operation, the air conditioner ECU 50 sets in advance a difference (T ₁ −T ₂ , inlet / outlet temperature difference) between the refrigerant inlet temperature T ₁ and the refrigerant outlet temperature T ₂ detected by the first and second temperature sensors. to be switched to the heating operation from defrosting operation When becomes less than the threshold value T ₀ that is. This “switchable” means “permit switching if there is a heating command”.

During the defrosting operation, in accordance with the refrigerant is deprived of heat for defrosting, but towards the coolant outlet temperature T ₂ than the refrigerant inlet temperature T ₁ is lowered temperature, proceeds defrosting, the temperature drop Therefore, the inlet / outlet temperature difference (T ₁ −T ₂ ) becomes small, and if the threshold value T ₀ is appropriately set by a test or the like, the state where the defrosting is completed can be estimated.
Further, the vehicle is provided with a cooling device that cools the running motor and the battery (not shown). The cooling device enters the external heat exchanger 3 during heating operation or defrosting operation. A first supply path 22 for supplying the refrigerant before the cooling to the cooling device, and a first return path 23 for returning the warmed refrigerant after passing through the cooling device to the upstream of the external heat exchanger 3 (see FIG. 1 (a)).

The vehicle further includes a second supply path 24 that supplies the cooling device with the low-temperature refrigerant before entering the internal heat exchanger 5 during the cooling operation, and the passage of the cooling device. You may have the 2nd return path 25 which returns the subsequent heating refrigerant | coolant to the downstream of the internal heat exchanger 5 (refer FIG.1 (b)).
Further, as shown in FIG. 2, the external heat exchanger 3 has a tube 31 through which a refrigerant circulates while being bent, and fins 32 are provided around the tube 31. Although these detailed shapes are not shown in FIG. 2, the refrigerant flows into the tube 31 from the refrigerant inlet 3 </ b> A and absorbs or dissipates heat through heat exchange with the outside air through the fins 32 while flowing through the tube 31. It flows out from the refrigerant outlet 3B.

  In the present embodiment, in the front view of the external heat exchanger 3, the main portion (portion excluding the bent portion) of the tube 31 extends in the vertical direction (vertical direction), and each fin 32 extends in the horizontal direction (horizontal direction). However, as an aspect of the heat exchanger, the main portion (excluding the bent portion) of the tube 31 extends in the horizontal direction (horizontal direction), and each fin 32 extends in the vertical direction (vertical direction). There will be described later.

Moreover, in FIG. 2, the tube 31 is described typically, and it may be bent to a denser number or may be bent more roughly.
As shown in FIG. 3, the tube 31 is formed in a flat shape with an oval cross section, and the fins 32 are fixed between flat surfaces of main portions (portions excluding bent portions) of the tube 31. ing. Further, in the present embodiment, the fin 32 is also bent between the flat surfaces of the tube 31 while being bent in the same manner as the tube 31, a portion joined to the tube 31, and a portion interposed between the flat surfaces of the tube 31, A characteristic structure is applied to the portion interposed between the flat surfaces of the tube 31 as described later.
Of course, the entire structure of the tube 31 and the fin 32 is not limited to such a bent structure, and the entire structure is not limited to this as long as it has a characteristic configuration to be described later.
Here, the characteristic point of this external heat exchanger 3 is demonstrated.

  As shown in FIG. 3, each of the fins 32 of the external heat exchanger 3 is provided with a coat layer having water repellency on the surface (at least the upper surface). As this coat layer, for example, processing by thermal spraying of a fluororesin such as Teflon (registered trademark) can be considered. Due to this coat layer, water hardly adheres to the surface of the fin 32, and accordingly, frost formation on the surface of the fin 32 hardly occurs, and icing on the surface of the fin 32 hardly occurs.

  In addition, although this coat layer is effective for preventing water from adhering to the entire external heat exchanger 3 to be processed on the entire surface of the fin 32 and the entire surface of the tube 31, among the surfaces of the fin 32 and the tube 31, It is also effective to process the coat layer only on one surface where water is most likely to adhere. The surface to which water is most likely to adhere is generally a surface facing vertically upward (including a surface inclined and facing upward), but a surface facing the traveling direction (inclined and facing the traveling direction). It can also be said that water is easily attached to the surface.

  Each fin 32 extends in the lateral direction (horizontal direction) as shown in FIG. 2 in the front view, but outside air that exchanges heat as shown in FIGS. 3 and 5 in the side view. It is inclined with respect to the flow (fresh direction) of (fresh air). In the first example shown in FIG. 3 and FIG. 5 and the second example shown in FIG. 4, it is inclined forward toward the outside air so as to raise the downstream side in the flow direction of the outside air, but the third example shown in FIG. Further, as in the fourth example shown in FIG. 7, it may be inclined rearward toward the outside air so as to lower the downstream side in the flow direction of the outside air. Due to such an inclination, even if water adheres to the surface of the fin 32, it quickly drops, so that frost formation on the surface of the fin 32 is less likely to occur, and icing on the surface of the fin 32 is less likely to occur.

  In addition, here, each fin 32 is cut into the inclined fin bodies 32a to 32c, and the bent piece portions 33a to 33c are bent. Holes 34a to 34c are formed in the fin bodies 32a to 32c by forming the bent pieces 33a to 33c. The bent pieces 33a to 33c increase the contact area with the entering outside air, while water drops and the like on the surface of the fin 32 are also quickly dropped by the holes 34a to 34c. In addition, icing on the surface of the fin 32 hardly occurs.

  As shown in FIGS. 3 and 5 and the third example shown in FIG. 6, the bent pieces 33 a to 33 c are formed by forming creases in the direction connecting the tubes 31 on both sides of the fin 32. Folding pieces are formed by bending the end portions 33a and 33c so that the tips of the portions 33a and 33c move up and down, or by forming a crease along the inclination direction of the fin 32 as in the second example shown in FIG. It can be bent such that the tip of 33b moves up and down, and various variations are conceivable.

The dropping performance of water droplets and the like varies depending on the front and rear inclinations of the fins 32 and the shape of the bent pieces 33a to 33c, which will be described later.
3 to 7, the fins 32 are inclined. However, the present invention is not limited to this. By tilting the entire external heat exchanger 3 in the backward inclined state or the forward inclined state, the fins 32 are inclined with respect to the horizontal plane. May be tilted backward or forward. In this case, even if the fin 32 is formed in a direction orthogonal to the extending direction of the main part of the tube 31 without being inclined with respect to the tube 31, the fin 32 is also formed by inclining the entire external heat exchanger 3. Will be inclined.

Since the vehicle heat pump air conditioner according to the embodiment of the present invention is configured as described above, the cooling operation and the heating operation are performed as follows.
First, at the time of cooling operation, as shown in FIG. 1B, the switching valve 2 generates a flow in the opposite direction to that at the time of heating operation by the control of the air conditioner ECU 50. The refrigerant is circulated in the order of the heat exchanger 3, the expansion valve 4, and the internal heat exchanger 5. At this time, the on-off valve 20 is opened, the on-off valve 21 is closed, and the refrigerant does not flow through the bypass flow path 19 constituting the defrosting operation circuit. Therefore, the cooling operation is performed using the external heat exchanger 3.

  As a result, the refrigerant that has been compressed by the compressor 1 and has become high temperature and high pressure is cooled and condensed in the external heat exchanger 3 by releasing heat by the outside air such as traveling wind. At this time, the external heat exchanger 3 functions as a condenser (condenser). The condensed refrigerant is cooled by adiabatic expansion in the expansion valve 4, and then takes the heat of the surrounding air in the internal heat exchanger 5, and the temperature rises by that amount and proceeds to the compressor 1. At this time, the internal heat exchanger 5 functions as an evaporator (evaporator). The vehicle interior in which the internal heat exchanger 5 is installed is cooled by the circulation (refrigeration cycle) of the refrigerant.

On the other hand, during the heating operation, as shown in FIG. 1 (a), the switching valve 2 generates a flow in the opposite direction to that during the cooling operation under the control of the air conditioner ECU 50. The refrigerant is circulated in the order of the heat exchanger 5, the expansion valve 4, and the external heat exchanger 3.
As a result, the refrigerant that has been compressed by the compressor 1 and has reached a high temperature and a high pressure releases heat in the internal heat exchanger 5 and is cooled and condensed. At this time, the internal heat exchanger 5 functions as a condenser (condenser). The condensed refrigerant is cooled by adiabatic expansion in the expansion valve 4, and then takes the heat of surrounding air in the external heat exchanger 3, and the temperature rises by that amount and proceeds to the compressor 1. At this time, the external heat exchanger 3 functions as an evaporator. The room in which the internal heat exchanger 5 is installed is heated by such refrigerant circulation (heat pump cycle).

At this time, if the external heat exchanger 3 is frosted or has a high possibility of frosting, the on-off valve 20 is closed and the on-off valve 21 is opened to form a defrosting operation circuit 19. Circulate refrigerant and perform defrosting operation.
In particular, in this air conditioner, when the vehicle is started, the defrosting operation is performed as shown in the flowchart of FIG. In FIG. 8, “F” is a control flag that is “1” during the defrosting operation and “0” in other cases. The flowchart of FIG. 8 is repeated at a predetermined cycle after startup.

  As shown in FIG. 8, first, it is determined whether or not the control flag F is 0 (step S10). If the control flag F is 0, this time is detected by an outside air temperature sensor (outside air temperature detecting means) (not shown). It is determined whether or not the outside air temperature detected in step 1 or the outside air temperature based on the history or average value of the outside air temperature detected during the most recent predetermined time before the start is equal to or lower than a preset reference temperature ( Step S20).

  Here, if the outside air temperature is equal to or lower than the reference temperature, it is determined that frost formation has occurred, the defrosting operation start condition is established, and the defrosting operation is performed (step S30). Then, the control flag F is set to 1 (step S40). On the other hand, if the outside air temperature is higher than the reference temperature, the defrosting operation start condition is not satisfied because frost formation has not occurred, and if there is a heating command, the heating operation is performed (step S50). Then, the control flag F is set to 0 (step S60).

When carrying out the defrosting operation, the next cycle, the process proceeds from step S10 to step S70, the difference between the refrigerant inlet temperature _{T 1} of the coolant outlet temperature _{T 2 (| T 1 -T 2} |, inlet and outlet temperature difference) is set in advance It was determined to whether it is less than the threshold _{T 0,} inlet and outlet temperature difference _(| T 1 _-T 2 |) switched to the heating operation from defrosting operation When becomes less than the threshold value _{T 0} (step S50). Then, the control flag F is set to 0 (step S60).

  Therefore, according to the vehicle heat pump air conditioner, the heat pump air conditioner can be applied to the vehicle air conditioner, and cooling and heating can be performed only by the heat pump circuit. On the other hand, if the external heat exchanger 3 is frosted, the heating operation is hindered. In particular, when the vehicle is started at a very low temperature in a cold region, the external heat exchanger 3 is likely to be frosted. In this regard, at the time of start-up, the external heat exchanger 3 disposed outside the vehicle is appropriately judged from the outside air temperature to determine whether there is frost formation, and by performing the defrost operation, the heating operation in a state where the frost is formed at the start-up Can be avoided. Moreover, the completion of defrosting can be appropriately determined by a simple method from the inlet / outlet temperature difference of the external heat exchanger 3, and the heating operation can be started.

  Further, the cooling device that cools the traveling motor and the battery uses the first supply path 22 and the first return path 23 during the heating operation or the defrosting operation, and also uses the second supply path during the cooling operation. 24 and the second return path 25 can be used to supply a coolant with high sealing performance to cool the traveling motor and the battery. For this reason, in the vehicle using a general lithium ion battery as a battery, the potential heat generation risk by using water can be avoided.

At the time of heating operation or defrosting operation, the temperature of the refrigerant to be increased in temperature can be increased at the same time as the traveling motor and the battery are cooled, which is effective.
In addition, since the fin 32 of the external heat exchanger 3 is provided with a coating layer having water repellency on the surface (at least the upper surface), it is difficult for water to adhere to the surface of the fin 32 by this coating layer. As much as that, frost formation on the surface of the fin 32 hardly occurs, and icing on the surface of the fin 32 hardly occurs.

  Further, since each fin 32 is inclined backward or forward in the direction of the flow of outside air formed by the traveling wind or the fan 7, water hardly adheres to the surface of the fin 32, and adhering water droplets are also present. It is easy to drip quickly from the rear or front edge of the fin 32. Due to such an inclination, water hardly adheres to the surface of the fin 32, and accordingly, frost formation on the surface of the fin 32 hardly occurs, and icing on the surface of the fin 32 hardly occurs. As shown in FIG. 3 and FIG. 5, it is provided so as to be inclined with respect to the flow (fresh direction) of the outside air (fresh air) for heat exchange. In the first example shown in FIG. 3 and FIG. 5 and the second example shown in FIG. 4, it is inclined forward toward the outside air so as to raise the downstream side in the flow direction of the outside air, but the third example shown in FIG. Further, as in the fourth example shown in FIG. 7, it may be inclined rearward toward the outside air so as to lower the downstream side in the flow direction of the outside air. Such an inclination increases the area directly exposed to the incoming outside air, thereby improving the heat exchange performance and preventing water from adhering to the surface of the fin 32. Therefore, frost formation on the surface of the fin 32 is less likely to occur. , Freezing on the surface of the fin 32 hardly occurs.

  In addition, since the bent pieces 33a to 33c are formed by bending the inclined fin bodies 32a to 32c and the holes 34a to 34c are formed, the bent pieces 33a to 33c increase the contact area with the outside air that enters. Therefore, the heat exchange performance is improved, and water droplets and the like on the surface of the fin 32 are quickly dripped by the holes 34a to 34c. Also from this point, water hardly adheres to the surface of the fin 32. Frosting on the surface hardly occurs, and icing on the surface of the fin 32 hardly occurs.

5-7, the running wind is indicated by a white arrow, the water drop on the fin 32 is indicated by a white circle, and the movement is indicated by an arrow. The movement wind is used to remove the water drop. In that respect, if both the fin 32 and the bent piece 33 are inclined rearward toward the traveling wind (outside air), water droplets can be removed more quickly, and the area directly hitting the traveling wind is increased. Is. From this point, it can be said that the third example shown in FIG. 6 is most effective.
In addition, as shown in FIG.5 (b) and FIG.6 (b), you may provide the bending piece part 33 with two or more in each fin 32 (two in each modification).

[Others]
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, In the range which does not deviate from the meaning of this invention, the said embodiment can be changed suitably and can be implemented.

For example, in the above embodiment, the defrosting operation start condition is determined using the temperature sensors installed at the inlet and outlet of the outdoor unit and the outside air temperature sensor (not shown). For example, a temperature sensor may be added, and this may be used as a determination condition of the control logic.
Further, the on-off valves 20 and 21 as switching means may be applied with PIC control using an intermediate opening degree of the on-off valve, instead of the on-off control that is merely fully closed or fully opened.

Further, the tube or fin may not have a bent piece or a hole, and the inclination is not essential. The bent piece may not be a flat plate as in the embodiment.
Further, in the above embodiment, the tube 31 is oriented in the vertical direction (vertical direction) and the fins 32 are oriented in the horizontal direction (horizontal direction) in the front view of the heat exchanger. The orientation direction is not limited to this. The tube may be in the horizontal direction (horizontal direction), and the fin may be in the vertical direction (vertical direction).

  In this case, it is preferable that the flat surface of the main part (other than the bent part) of the tube is inclined forward or backward with respect to the traveling wind. Further, the flat surface of the tube may be inclined backward or forward with respect to the horizontal plane by inclining the entire external heat exchanger in the backward inclined state or the forward inclined state. In this case, even if the flat surface of the main part of the tube is formed in a direction perpendicular to the extending direction of the fin without being inclined with respect to the fin, the flat surface of the tube is formed by inclining the entire external heat exchanger. Will also be inclined.

  In the embodiment, a coat layer having water repellency is provided on at least one surface (particularly upward surface) of the fin in order to prevent water droplets from adhering to the tube. It may be provided. In particular, when the tube extends in the lateral direction (horizontal direction), this is effective for preventing the adhesion of water drops to the upward surface of the flat surface of the tube.

1 Compressor 2 Switching valve 3 External heat exchanger (outdoor unit)
3A Refrigerant inlet 3B Refrigerant outlet 4 Expansion valve 5 Internal heat exchanger (indoor unit)
5a Fan 6 Accumulator 7 Fan 10 Refrigerant circuit 11-17 Flow path of refrigerant circuit 19 Bypass flow path (defrosting operation circuit)
20, 21 On-off valve as switching means 22 First supply path 23 First return path 24 Second supply path 25 Second return path 31 Tube 32 Fin 32a-32c Fin body 33a-33c Bending piece 34a-34c Hole 41 First 1 temperature sensor (first refrigerant temperature detecting means)
42 2nd temperature sensor (2nd refrigerant temperature detection means)
50 Air conditioner ECU as control device

Claims (6)

A heat exchanger equipped with a compressor, an external heat exchanger, an expansion valve, and an internal heat exchanger in a refrigerant circuit as a vehicle heat pump air conditioner as the external heat exchanger,
A plurality of tubes arranged side by side in the longitudinal direction and through which refrigerant flows;
Fins disposed laterally between the tubes, and
A heat exchanger, wherein a coat layer having water repellency is provided on at least one surface of the fin or the tube. 2. The heat exchanger according to claim 1, wherein the fin or the tube is inclined backward or forwardly toward an outside air inflow direction. The heat exchanger according to claim 1 or 2, wherein the fin or the tube is cut to form a bent piece portion, and a hole is formed by forming the bent piece portion. . 4. The heat exchanger according to claim 3, wherein the fin or the tube is inclined backward toward the outside air inflow direction, and the bent piece portion is inclined toward the outside air inflow direction. A heat pump air conditioner for a vehicle having a compressor, an external heat exchanger, an expansion valve, and an internal heat exchanger in the refrigerant circuit,
The heat exchanger of any one of Claims 1-4 is used as the said external heat exchanger, The heat pump type air conditioner for vehicles characterized by the above-mentioned. The bypass channel for supplying a high-pressure refrigerant from the compressor to the external heat exchanger at the time of defrosting operation is provided between the compressor and the external heat exchanger. Item 6. A heat pump air conditioner for a vehicle according to Item 5.

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