JP2000289451A - Air conditioning system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning system for vehicle capable of improving cool down performance more than existing refrigerating cycle while saving power. SOLUTION: A bypass passage 1 bypassing an evaporator 26 is provided in a duct 20 of an air conditioning device, an evaporator 16 of a suction type refrigerator 10 using exhaust heat of a vehicle as a heat source is installed in the bypass passage 1, this evaporator 16 is surrounded by a cold accumulation vessel 15b storing a cold storage medium 15a, and air conditioned air sent from a blower 21 is cooled by cold dissipation of the cold storage medium 15a at the time of cooling and dehumidification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a vehicle using an absorption refrigerator using waste heat as auxiliary cooling.

[0002]

2. Description of the Related Art In recent years, power saving of vehicles has been actively performed due to environmental problems. One of the methods for promoting power saving is a method of effectively utilizing energy discarded from vehicles. In vehicle air conditioners, the use of waste heat utilizing the heat of engine cooling water during heating is in practical use.However, when dehumidifying during heating, it is necessary to temporarily cool the blown air with an evaporator. The compressor had to be operated in a short time, and labor saving could not be said to be sufficient.
Also, during cooling, effective exhaust heat treatment has not been performed in the current refrigeration cycle. Therefore, it is conceivable to perform cooling and dehumidification by using an absorption refrigerator that operates an absorption cycle using heat of an engine cooling water, an exhaust manifold, or a muffler. This is because water or a solution in which an inorganic salt such as an aqueous solution of sodium chloride is dissolved is used as a refrigerant, and an aqueous solution of lithium bromide or ammonia having a strong affinity for water is used as an absorbent for the refrigerant. This is a refrigeration cycle utilizing the absorption of water and the release of the absorbed refrigerant in a high-temperature part, which does not have an electric motor such as a compressor but performs a refrigeration action by a chemical cycle using a heat source.

[0003]

However, when the exhaust heat of a vehicle is used as a heat source, the above-mentioned absorption refrigerator has a lack of stability because the exhaust heat temperature is not constant. Until the exhaust heat is obtained, cooling or dehumidification cannot be performed, and therefore, there has been a problem that the cool-down performance and the window clear performance deteriorate. In addition, since cooling is performed only by an absorption refrigerator, the size of the apparatus becomes large, which is not practical.

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional problems, and an object of the present invention is to provide an air conditioner for a vehicle that can improve the cool down performance more than the current refrigeration cycle while realizing power saving. Aim.

[0005]

According to a first aspect of the present invention, there is provided an air conditioner for a vehicle, wherein a passage for bypassing an evaporator is provided in a duct of the air conditioner, and an evaporator of an absorption refrigerator is installed in the passage. In this case, cooling, cooling down, or dehumidification is assisted.

According to a second aspect of the present invention, a cooling agent for exchanging heat with the evaporator is arranged around the evaporator, and cool heat from the evaporator is stored in the cooling agent. Things.

According to a third aspect of the present invention, the vehicle air conditioner includes a bypass switching door that opens and closes the bypass passage, and when the temperature of the regenerator is lower than a predetermined temperature during cooling, the bypass switching is performed. The door is opened to provide cooling or cooling down assistance.

According to a fourth aspect of the present invention, there is provided a vehicle air conditioner having a bypass switching door for opening and closing the bypass passage, and when the temperature of the regenerator is lower than a predetermined dew point during dehumidification. The switching door is opened to dehumidify the conditioned air.

According to a fifth aspect of the present invention, there is provided an air conditioner for a vehicle, wherein an absorber of an absorption refrigerator is cooled by a Peltier element.

According to a sixth aspect of the present invention, the vehicle air conditioner uses exhaust heat of the vehicle as a heat source of the absorption refrigerator to heat the generator of the absorption refrigerator.

According to a seventh aspect of the present invention, there is provided an air conditioner for a vehicle, wherein a generator of an absorption refrigerator and a heat source are connected by a heat pipe.

[0012] In the vehicle air conditioner according to the present invention, a Seebeck element is attached to a part of an exhaust pipe, and electric power obtained by heat-exchanging the exhaust heat of the exhaust pipe by the Seebeck element is supplied to a refrigerant pump, a condenser fan, This is used for at least a part or all of the electric power required for operating the absorption refrigerator such as a Peltier device.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a vehicle air conditioner according to the present embodiment.
In the figure, reference numeral 20 denotes a duct of an air conditioner, 21 denotes a blower for blowing air, 22 denotes a compressor connected to an engine (not shown) via an electromagnetic clutch, and compresses a low-pressure refrigerant to discharge a high-temperature and high-pressure gas refrigerant; Is a condenser that cools and condenses the gas refrigerant, 24 is a receiver tank that separates the condensed refrigerant into gas and liquid, and 25 is an adiabatic expansion of the high-temperature and high-pressure liquid refrigerant sent from the receiver tank 24 to reduce the temperature. An expansion valve using a low-pressure refrigerant, 26 is a duct 2
0, an evaporator for cooling the blast air by heat exchange between the air sent by the blower 21 and the low-temperature and low-pressure refrigerant, a heater 27 for heating the blast air,
Reference numeral 28 denotes an air mix door for adjusting the temperature of the blast air by adjusting the amount of air passing through the heater 27 in the blast air cooled by the evaporator 26 according to the degree of opening and closing.

During cooling, the compressor 22 compresses the low-pressure refrigerant and sends it to the condenser 23 as a high-temperature and high-pressure gas refrigerant. The gas refrigerant is cooled and condensed in the condenser 23 to become a refrigerant in which a gas phase and a liquid phase are mixed. This refrigerant is gas-liquid separated in the receiver tank 24, and the liquid refrigerant is sent to the expansion valve 25. The refrigerant is adiabatically expanded in the expansion valve 25 to become a low-temperature and low-pressure refrigerant.
Sent to 6. The evaporator 26 exchanges heat with the low-temperature and low-pressure refrigerant that is introduced into the duct 20 from outside the vehicle compartment or from outside the vehicle and sent by the blower 21 to cool the blast air. The cooled air is sent into the vehicle interior from an upper outlet or a lower outlet (not shown). During heating, the air blown from the blower 21 is heated by the heater 27 and sent into the vehicle interior.
When dehumidification is performed during heating by the evaporator 26, the compressor 22 is operated to operate the evaporator 26.
The cooling air is cooled to reduce the moisture contained in the blowing air, and the opening / closing degree of the air mixing door 28 is adjusted to control the amount of air passing through the heater 27 out of the blowing air to control the blowing air. By adjusting the temperature, the dehumidified air is sent into the vehicle interior.

In FIG. 1, reference numeral 1 denotes a bypass passage provided in the duct 20 for bypassing the evaporator 26;
2 is a bypass switching door provided on the entrance side of the bypass passage 1; 10 is a generator 11;
A heat exchange unit 15 provided in the bypass passage 1 and including a condenser 13 having a refrigerant, an expansion valve 14, a cold storage container 15b for storing a cold storage agent 15a, and a cold storage container 15c for storing the cold storage container 15b. , An evaporator 16 constituting a part of the heat exchange unit 15 and an absorber 18 to which a Peltier element 17 as cooling means is attached.
And a refrigerant pump 19. 2
Reference numeral 9 denotes an exhaust pipe of the engine, and reference numeral 30 denotes a Seebeck effect thermoelectric conversion element (hereinafter referred to as a Seebeck element) attached to the exhaust pipe 29. The exhaust heat from the exhaust pipe 29 is
In order to prevent the temperature of an unillustrated exhaust gas purifying catalyst provided in the exhaust pipe 29 from lowering and hindering the exhaust gas treatment, the exhaust gas is collected downstream of the catalyst.

In the absorption refrigerator 10, when a refrigerant (here, water) using an aqueous ammonia solution as an absorbing material is heated by the exhaust heat of the exhaust pipe 29 in the generator 11, the absorbent is absorbed. The refrigerant is released and gasified. The gas enters the condenser 13 and is cooled, liquefied and concentrated into an aqueous ammonia solution. The liquid refrigerant expands at the expansion valve 14, and is heated and vaporized by heat exchange with the regenerator 15a in the evaporator 16. The heat of vaporization cools the cold storage agent 15a of the heat exchange unit 15 and cools the blast air sent into the bypass passage 1. In the absorber 18, by cooling the vaporized ammonia gas, the refrigerant absorbs the refrigerant, is liquefied again, becomes a diluted aqueous ammonia solution, and is returned to the generator 11 by the refrigerant pump 19. FIG. 2 is a diagram showing details of the structure of the absorber 18. In the absorber 18, heat is exchanged between the heat absorbing fins 17a attached to the heat absorbing side of the Peltier element 17 and having a low temperature and the vapor refrigerant vaporized in the evaporator 16. By doing so, the vapor refrigerant is efficiently returned to the liquid refrigerant. The heat absorbing fins 17a are connected to the absorber 1
8 are arranged from the upper part to the lower part, and the absorber 18
The liquid refrigerant below is also cooled to efficiently absorb the refrigerant. A radiating fin 17b and a fan 17c for cooling the radiating fin 17b are attached to the radiating side of the Peltier element 17, so that the heat exchange efficiency of the Peltier element 17 is improved. As described above, when the refrigerant and the absorbent are ammonia and water, a cooling power of 0 ° C. or less can be obtained. Therefore, as the regenerator 15a, inorganic water such as Mgcl, Nacl or Cacl ₂ is used as the regenerator 15a. A mixture of salts may be used, and a water-soluble organic substance such as methanol or glycol may be further added. The cold storage agent 15a is frozen at a temperature of 0 ° C. or less by the absorption refrigerator 10, and the latent heat of the cold storage agent 15a is used. And sensible heat (see FIG. 4).

FIGS. 3A and 3B show the heat exchange unit 15.
FIG. 2 is a diagram illustrating an example of the configuration of a heat exchanger.
A heat storage fin 16f, which is a heat radiation fin, and an outer heat exchange fin 15f that exchanges heat with conditioned air, are surrounded by a cold storage agent container 15b that contains a cold storage agent 15a, and the cold storage agent container 15b is further enclosed. In the structure surrounded by the cool storage container 15c, heat is exchanged between the evaporator 16 and the cool storage container 15b, and a bypass is provided between the cool storage container 15b and the cool storage container 15c to the ventilation passage 15s. By flowing the blast air introduced into the passage 1, heat exchange between the blast air and the cold storage agent 15a is performed to cool the blast air. The inner heat exchange fins 16f forming the inner surface of the cold storage agent container 15b are
And a delivery pipe 16b for delivering the refrigerant from the evaporator 16 respectively. Also,
This inner heat exchange fin 16f is formed by combining the regenerator 15a contained between the inner heat exchange fin 16f and the outer heat exchange fin 15f forming the outer surface of the regenerator 15b with the refrigerant in the evaporator 16. In order to increase the contact area with
The structure is such that a plurality of cylindrical protrusions 16p protrude from above and below into the inside of the evaporator 16. As shown in FIG. 3 (c), a plurality of projections 15p for increasing the contact area with the blast air are also provided on the outer peripheral side of the outer inner heat exchange fin 15f. a),
(B) is omitted because the figure is complicated.

The heat exchange unit 15 closes the bypass switching door 2 at the time of cold storage, cools the cold storage agent 15a by heat exchange between the evaporator 16 and the cold storage agent 15a, and opens the bypass switching door 2 at the time of cooling. The heat exchange unit 15
It operates to cool the blast air by heat exchange between the blast air sent to the chiller and the regenerator 15a. At this time, the temperature of the cold storage agent 15a during cold storage is as shown in FIG.
As shown in (1), the temperature decreases with time due to heat exchange with the evaporator 16, the temperature becomes constant at the freezing point temperature B of the regenerator 15a (latent heat portion), and thereafter, the temperature decreases with time. Note that a temperature C lower by a predetermined temperature than the freezing point temperature B is regarded as a temperature at which cold storage is completed, and this temperature C is set as a cold storage completion set temperature C. Further, as shown in FIG. 4B, the temperature of the cold storage agent 15a at the time of cooling is increased with time by heat exchange with the blast air, becomes constant in the latent heat portion, and then increases with time. .

Next, the operation of the vehicle air conditioner having the above configuration will be described with reference to the temperature characteristics of the regenerator shown in FIG. 4 and the control flow shown in FIG. First, in the ON state of the air conditioner, it is determined whether the operation mode is the cooling operation or the heating operation (step S1). When the operation mode is cooling operation,
It is checked whether or not the cold storage is performed, that is, whether or not the temperature T of the cold storage agent 15a is equal to or lower than the freezing point temperature B (step S2). If T ≦ B, the bypass switching door 2 is opened to exchange the blown air with heat. The air is sent to the unit 15 and heat exchange between the regenerator 15a and the blast air is performed to cool the blast air, thereby assisting cooling or cooling down (step S3). If T> B, the bypass switching door 2 is closed (step S4), and it is checked whether or not the temperature T of the cold storage agent 15a has reached the cold storage completion set temperature C (step S5). Returning to S2, it is determined again whether or not cooling can be performed.
If> C, the process returns to step S4 to continue the cold storage operation.

If the operation mode is the heating operation, it is next determined whether a dehumidification request has been issued (step S).
6). If there is a dehumidification request, the temperature T of the regenerator 15a
It is checked whether or not the temperature is below the preset dew point temperature H (step S7). If T ≦ H, the bypass switching door 2 is opened to send the blast air to the heat exchange unit 15, and the regenerator 15a and the above Heat exchange with the blast air is performed to cool the blast air to reduce the moisture contained in the blast air, and to adjust the opening / closing degree of the air mix door 28 to pass through the heater 27 of the blast air. The dehumidified air is sent into the vehicle cabin by controlling the amount of air to adjust the temperature of the blown air (step S8). Here, the dew point temperature H is calculated based on an empirical formula using the temperature and the relative humidity in the vehicle compartment as parameters. When dehumidification is performed by allowing the cool storage agent 15a to cool, the compressor 22 is in a stopped state because the heat exchange unit 15 plays the role of the evaporator 28. If T> H in step S7, the bypass switching door 2 is closed (step S9), and it is checked whether or not the temperature T of the cold storage agent 15a has reached the dew point temperature H (step S9).
10) If T.ltoreq.H, the process returns to step S7 to determine whether cooling can be performed again. If T> H, the compressor 22 is operated to perform dehumidification by the evaporator 26 (step S11).

If there is no dehumidification request in step S6, the bypass switching door 2 is closed (step S6).
12) While continuing cold storage, it is checked whether the temperature T of the cold storage agent 15a has reached the cold storage completion set temperature C (step S).
13) If T ≦ C, it is determined that the cold storage has been completed, and the cold storage system is stopped (step S14). If T> C, the process returns to step S12 to continue the cold storage. In addition,
When the temperature of the window (the temperature of the window glass) obtained from the output of the temperature sensor of the window installed on the vehicle window or the output of the outside air temperature sensor (not shown) is T _W , when T _W ≦ H, The control flow is performed by using the window temperature T _W instead of the dew point temperature H, and using the dew point temperature H when T _W > H.
The dew point temperature H or the window temperature T _W is usually higher than the freezing point temperature B. However, in cold regions, etc., the window temperature T _W may be lower. In addition, the freezing point temperature B of the regenerator 15a is lowered so that B <H (B <T _W ). Therefore, when there is a dehumidification request in the case of the heating operation,
The temperature of the vehicle interior and the temperature of the window glass are detected, and the cold storage agent 15a is detected.
If it is determined that dehumidification is possible at or below the predetermined dew point temperature, dehumidification is performed using only the heat exchange unit 15 without operating the compressor 22, so that power saving can be achieved. Further, since the absorption type refrigerator 10 performs only cooling assistance and dehumidification, a small system is required. Therefore, the refrigerant pump 19 and the condenser are heated by electric power exchanged by the Seebeck element 30 attached to a part of the exhaust pipe 29. The fan 12 and the Peltier element 17 for cooling the absorber can be sufficiently driven.

As described above, according to the present embodiment, the duct 20 of the air conditioner is provided with the bypass passage 1 for bypassing the evaporator 26, and the absorption refrigeration using the exhaust heat of the vehicle as a heat source in the bypass passage 1. The evaporator 16 of the machine 10 is installed, and the evaporator 16 is surrounded by a regenerator 15b containing a regenerator 15a. During cooling or dehumidification, the air-conditioning air sent from the blower 21 is cooled by cooling the regenerator 15a. As a result, extra energy is not required, and cooling and cooling down can be assisted or dehumidification can be performed. Therefore, the load on the compressor can be reduced, and power saving can be achieved. Further, by assisting the main cooling during the steady operation, the operability is improved by reducing the number of ON / OFF operations of the compressor, and the reliability of the clutch and the like is improved. Further, even after the vehicle stops, if there is exhaust heat, the stored air can be used to cool the conditioned air, so that the cool-down performance can be improved, and the cold storage and dehumidification can be performed, so that the comfort is improved. In addition, the compressor 2 is used only for dehumidification in winter.
Since it is not necessary to operate the power supply 2, labor saving during heating can be further promoted. Further, even if the main compressor is stopped after idling is stopped, cooling and dehumidification by cold storage are possible.

In the above embodiment, the case where the generator 11 is directly mounted on the exhaust pipe 29 has been described. However, as shown in FIGS. 11 and the exhaust pipe 29 and the generator 11
May be connected by a heat pipe 31 so that the exhaust heat of the exhaust pipe 29 is transmitted to the generator 11 and collected.
The heat pipe 31 fills the inside of the space between the hollow metals with the refrigerant F, and transmits waste heat by the refrigerant F.
At both ends of the heat pipe 31, heat sinks 32 inserted into the exhaust pipe 29 and the generator 11, respectively, are provided.
a and 32b are provided. Here, the refrigerant F heated by the exhaust pipe 29 rises in the heat pipe 31 and transmits the exhaust heat of the exhaust pipe 29 to the generator 11, and the refrigerant F that has undergone heat exchange and is cooled by the generator 11 is: Exhaust pipe 29 becomes liquid
Fall to the side. Here, it goes without saying that the heat sink 32b of the exhaust pipe 29 is installed so as not to obstruct the flow of the exhaust gas. When the piping is long, etc.
As shown in (c), using a heat pipe 31K having a double pipe structure and having a vacuum insulated pipe with a vacuum between two pipes, or wrapping a heat insulating material around the outer periphery of the heat pipe 31. Thus, the loss of the exhaust heat transfer is reduced. The heat source of the generator 11 is not the exhaust heat from the exhaust pipe 29 but
The exhaust heat from the exhaust manifold may be used. In this case, the exhaust manifold and the generator are connected by the heat pipe 31, and since the temperature of the exhaust manifold is high, the exhaust manifold side of the heat pipe 31 is surrounded by a heat insulating material, and the temperature in the heat pipe 31 is reduced. It is necessary to keep the temperature at which the refrigerant does not decompose.

In the above example, the blast air introduced into the bypass passage 1 is caused to flow through the blast passage 15s provided between the cool storage container 15b and the cool storage container 15c of the heat exchange unit 15. The regenerator container 15b
May be installed in the bypass passage 1 or in the duct 20 behind the evaporator 26. At this time, the air passing through the bypass passage 1 forms the bypass passage 1 so as to be sent into the duct 20 from between the evaporator 26 and the cold storage container 15b. Further, in the above example, the exhaust heat of the exhaust pipe 29 is converted into electric power by the savec element 30 and is used as an electric power source to drive the refrigerant pump 19, the condenser fan 12, and the absorber cooling Peltier element 17. However, as described above, the absorption refrigerator 10
Since the system only requires cooling assistance and dehumidification, the system can be small, and a solar cell may be installed on the roof of the vehicle, the upper part of the trunk, the rear parcel, or the like to serve as the power source.
Further, the refrigerant and the absorbent used for the regenerator 15a and the absorption refrigerator 10 are not limited to the above examples, but are appropriately selected according to the specifications of the air conditioner. For example, the cold storage agent 15
Water may be used as a and lithium bromide may be used as the absorbent. Further, an inorganic powdery substance may be added to the cold storage agent 15a as an ice nucleation promoting agent to promote freezing.

[0025]

As described above, according to the first aspect of the present invention, a passage for bypassing an evaporator is provided in a duct of an air conditioner, and an evaporator of an absorption refrigerator is installed in this passage. In addition, since cooling, cooling down, or dehumidification is assisted, the load on the compressor can be reduced, and power saving can be achieved. In addition, by assisting the main cooling during the steady operation, the drivability is improved by reducing the number of times the compressor is turned on and off, and the reliability of the clutch and the like is improved.

According to the second aspect of the present invention, a regenerator that exchanges heat with the evaporator is arranged around the evaporator, and cool heat from the evaporator is stored in the regenerator. Even after the vehicle is stopped, the conditioned air can be cooled using the stored cold heat, so that the cool-down performance can be improved.
Furthermore, since it is possible to cool and dehumidify, it is possible to improve comfort.

According to the third aspect of the present invention, a bypass switching door for opening and closing the bypass passage is provided, and when the temperature of the regenerator is lower than a predetermined temperature during cooling, the bypass switching door is provided. Is opened, so that cooling or cooling down can be appropriately assisted.

According to the fourth aspect of the present invention, a bypass switching door for opening and closing the bypass passage is provided, and when the temperature of the regenerator is lower than a predetermined dew point during dehumidification, the bypass switching is performed. Since the door is opened, dehumidification of the conditioned air can be appropriately performed.

According to the fifth aspect of the present invention, since the absorber of the absorption refrigerator is cooled by the Peltier element, the absorber can be efficiently cooled with a simple configuration.

According to the invention of claim 6, since the exhaust heat of the vehicle is used as the heat source of the absorption refrigerator and the generator of the absorption refrigerator is heated, no extra energy is required. It can assist cooling or cooling down or dehumidify. Therefore, the load on the compressor can be reduced, and power saving can be achieved. Further, even after the vehicle stops, if there is exhaust heat, the stored air can be used to cool the conditioned air, so that the cool-down performance can be improved, and the cold storage and dehumidification can be performed, so that the comfort is improved. Further, since it is not necessary to operate the compressor only for dehumidification in winter or the like, labor saving during heating can be further promoted.

According to the present invention, since the generator and the heat source of the absorption refrigerator are connected by the heat pipe, even when the distance between the generator and the heat source is long, the heat of the heat source can be efficiently used. Can be conveyed in a targeted manner.

According to the eighth aspect of the present invention, a Seebeck element is attached to a part of the exhaust pipe, and the electric power obtained by heat-exchanging the exhaust heat of the exhaust pipe by the Seebeck element is transferred to a refrigerant pump, a condenser fan, or a Peltier device. Since it is used for at least part or all of the electric power required for the operation of the absorption refrigerator such as an element, waste heat can be used more effectively, and power saving can be further promoted.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 is a diagram showing details of a configuration of an absorber of the absorption refrigerator.

FIG. 3 is a diagram illustrating a configuration example of a heat exchange unit.

FIG. 4 is a diagram showing a change in temperature of a regenerator during cold storage and during cold storage.

FIG. 5 is a diagram showing a control flow of the vehicle air conditioner according to the present embodiment.

FIG. 6 is a diagram showing an example in which an exhaust pipe and a generator of an absorption refrigerator are connected by a heat pipe.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 bypass passage, 2 bypass switching door, 10 absorption refrigerator, 11 generator, 12 condenser fan, 13
Condenser, 14 expansion valve of absorption refrigerator, 15 heat exchange unit, 15a cold storage agent, 15b cold storage container, 15c
Cool container, 16 Evaporator, 17 Peltier device, 18
Absorber, 19 refrigerant pump, 20 duct, 21 blower, 22 compressor, 23 condenser, 24 receiver tank, 25 expansion valve, 26 evaporator, 2
7 heater, 28 air mix door, 29 exhaust pipe,
30 Seebeck element.

Claims (8)

[Claims] 1. An air conditioner for a vehicle, wherein a passage for bypassing an evaporator is provided in a duct of the air conditioner, and an evaporator of an absorption refrigerator is installed in the passage. 2. The vehicle air conditioner according to claim 1, wherein a regenerator that exchanges heat with the evaporator is arranged around the evaporator. 3. A bypass switching door for opening and closing the bypass passage, wherein the bypass switching door is opened when the temperature of the regenerator is lower than a predetermined temperature during cooling. The vehicle air conditioner according to claim 2, wherein 4. A bypass switching door for opening and closing the bypass passage, wherein the bypass switching door is opened when the temperature of the regenerator is lower than a predetermined dew point during dehumidification. The vehicle air conditioner according to claim 2, wherein: 5. The air conditioner for a vehicle according to claim 1, wherein the absorber of the absorption refrigerator is cooled by a Peltier element. 6. The air conditioner for a vehicle according to claim 1, wherein exhaust heat of the vehicle is used as a heat source of the absorption refrigerator. 7. The vehicle air conditioner according to claim 6, wherein the generator of the absorption refrigerator and the heat source are connected by a heat pipe. 8. A Seebeck element is attached to a part of an exhaust pipe, and at least a part or all of an electric power required for operating the absorption refrigerator is obtained by thermoelectrically exchanging the exhaust heat of the exhaust pipe by the Seebeck element. The vehicle air conditioner according to claim 1 or 5, wherein the air conditioner is used for a vehicle.