JP2011140291A - Air conditioner for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure heating capacity even when outside air has an extremely low temperature, in an air conditioner for a vehicle performing heating by a heat pump cycle. <P>SOLUTION: This air conditioner includes a compressor 21, an outdoor heat exchanger 22 outside a cabin, and an evaporator 13 in an air conditioning casing to switch any one of a cooling mode, a first heating mode and a second heating mode of a coolant circuit by switching means 27, 29 and 31. The coolant circuit of the heat pump cycle making coolant radiate heat by the heat radiator 14 and making the coolant absorb heat by the outdoor heat exchanger 22 is constituted during the first heating mode. The coolant circuit of a hot gas cycle for making the coolant flowing out of the heat radiator 14 flow into the compressor 21 by making the coolant bypass the outdoor heat exchanger 22 and the evaporator 13 after making high temperature vapor phase coolant after discharged from the compressor 21 radiate heat by the heat radiator 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle air conditioner including a refrigeration cycle.

  Conventionally, as a vehicle air conditioner equipped with a refrigeration cycle, an evaporator and a condenser disposed in an air conditioning case, and an outdoor heat exchanger disposed outside the passenger compartment, by a switching valve provided in the refrigerant circuit, Some are configured to be switchable between a cooling mode refrigerant circuit, a heating mode refrigerant circuit, and a dehumidifying mode refrigerant circuit. This heating mode is heating by a heat pump cycle. (For example, see Patent Document 1)

Japanese Patent No. 3331765

  By the way, in the heating mode by the heat pump cycle of the above-mentioned structure, there exists a problem that heating capability cannot be ensured at the time of external air very low temperature, such as -30 degreeC.

  As an example of this reason, when the outdoor temperature is extremely low, frost formation is likely to occur in the outdoor heat exchanger, and it is necessary to switch the operation mode from the heating mode to the defrosting mode every time the outdoor heat exchanger frosts. This is because the heating operation cannot be continuously performed.

  In view of the above points, an object of the present invention is to provide a vehicle air conditioner capable of ensuring a heating capability at a very low outside temperature.

In order to achieve the above object, according to the first aspect of the present invention, the refrigerant circuit switching means for switching to any one of the cooling mode refrigerant circuit, the first heating mode refrigerant circuit, and the second heating mode refrigerant circuit ( 27, 29, 31),
The refrigerant circuit in the first heating mode causes the refrigerant discharged from the compressor (21) to flow in the order of the radiator (14), the decompression means for heating (23), and the outdoor heat exchanger (22) in this order, and the outdoor heat exchanger ( 22) The refrigerant circuit that flows out of the refrigerant (22) and bypasses the evaporator (13) and leads it to the suction side of the compressor (21) so that the heat is absorbed by the outdoor heat exchanger (22) and is radiated by the radiator (14). Configure
The refrigerant circuit in the second heating mode causes the refrigerant discharged from the compressor (21) to flow into the radiator (14), and flows the refrigerant out of the radiator (14) into the outdoor heat exchanger (22) and the evaporator ( 13) by detouring both of them and guiding them to the suction side of the compressor (21) to constitute a refrigerant circuit for radiating heat with the radiator (14)
The switching means (27, 29, 31) changes the refrigerant from the first heating mode to the second heating mode when the physical quantity correlated with the heating capacity in the first heating mode reaches a value indicating the decrease side of the heating capacity. It is characterized by switching circuits.

  In the present invention, under the condition that the heating capacity in the first heating mode by the heat pump cycle decreases, the second heating mode is switched to the second heating mode in which the blown air is heated using the high-temperature gas-phase refrigerant (hot gas) flowing into the radiator as a heat source. I have to. And in this 2nd heating mode, since a refrigerant | coolant is not poured through an outdoor heat exchanger and an outdoor heat exchanger is not made to act as a heat sink, the defrosting operation | movement of an outdoor heat exchanger is unnecessary. Therefore, according to the present invention, it is possible to perform a continuous heating operation when the outside air is at a very low temperature, and it is possible to ensure the heating capacity.

In the invention according to claim 2, the air heating means (61) is arranged in the air conditioning case (11) on the downstream side of the air flow of the evaporator (13) and heats the blown air by a heat source different from the refrigeration cycle. With
The radiator (14) is disposed in the air conditioning case (11) on the downstream side of the air flow with respect to the air heating means (61), and the high-pressure side high-temperature refrigerant and the blown air after passing through the air heating means (61) It is characterized by heat exchange to dissipate the refrigerant.

  Here, for the purpose of protecting the compressor from the heat of each device of the refrigeration cycle, the compressor is normally controlled to protect the compressor at a low speed so that the discharge refrigerant temperature of the compressor is lower than a predetermined temperature. The

  In the first heating mode, as the outside air temperature decreases, the refrigerant pressure is reduced by the decompression means in order to increase the amount of heat absorbed by the outdoor heat exchanger, so the suction pressure of the compressor decreases and the compression ratio increases. Therefore, the discharge refrigerant temperature of the compressor rises. For this reason, in the 1st heating mode at the time of outside very low temperature, since the discharge refrigerant temperature of a compressor exceeds predetermined temperature, apparatus protection control which keeps the number of rotations of a compressor low works, and, as a result, heating capacity is substantial. Therefore, the desired heating capacity cannot be ensured.

  In contrast, in the second heating mode, heat is not absorbed by the outdoor heat exchanger, so that a decrease in the suction pressure of the compressor can be suppressed more than in the first heating mode, and the first heating when the target rotation speed of the compressor is the same. Temperature rise can be suppressed more than in the mode. For this reason, according to the 2nd heating mode, the fall of the heating capability by the above-mentioned apparatus protection control can be avoided.

  Furthermore, in the second heating mode, the amount of heat released by the radiator is determined by the compression work of the compressor. And as the inlet side air temperature of the radiator rises, the pressure on the high pressure side of the refrigerant rises in an attempt to secure the temperature difference between the refrigerant and the air in the radiator. The hot gas cycle is balanced so that the amount of heat released by the vessel increases (see FIG. 9).

  Therefore, in the present invention, when the operation mode is the second heating mode, the air after heating by the air heating means is flown into the radiator instead of the air immediately after passing through the evaporator, so that the refrigerant in the radiator The amount of heat release can be increased, and the heating capacity of the second heating mode can be improved. And according to this invention, according to the inlet side air temperature of a heat radiator, compared with the 1st heating mode with the same inlet side air temperature, it becomes possible to obtain a high heating capability (refer FIG. 10).

  Incidentally, unlike the present invention, the air heating means can be arranged on the downstream side of the radiator, but according to the present invention, the air heating means is arranged on the downstream side of the air flow of the radiator for the reasons described above. Compared to the case, the heating capacity of the radiator can be improved.

  Here, regarding the invention according to claims 1 and 2, the refrigerant circuit according to claims 3 and 4 can be employed as the refrigerant circuit in the second heating mode.

  In the refrigerant circuit according to claim 3, after the refrigerant discharged from the compressor (21) flows into the radiator (14), the refrigerant flowing out of the radiator (14) is decompressed by the decompression means (23). This is a refrigerant circuit that leads to the suction side of the compressor (21).

  On the other hand, the refrigerant circuit according to claim 4 is a refrigerant circuit which causes the refrigerant discharged from the compressor (21) to flow into the radiator (14) after being decompressed by the decompression means (71). According to this, compared with the refrigerant circuit of Claim 3, a heating capability can be improved for the following reasons. In the refrigerant circuit according to claim 4, since the refrigerant before flowing into the radiator is decompressed, the refrigerant after discharge from the compressor flows into the radiator without decompressing as in the refrigerant circuit according to claim 3. Compared with the case of making it, the temperature of the refrigerant | coolant which flows in into a heat radiator falls. For this reason, if it is going to make the temperature of the refrigerant | coolant which flows in into a radiator into the same level as the case where it flows in into a radiator without decompressing the refrigerant | coolant after discharge of a compressor, the work of a compressor will increase. It is.

  In addition, the switching of the refrigerant circuit from the first heating mode to the second heating mode is performed when the outside air temperature (Tam) is lower than a predetermined temperature (T1) as in the invention described in claim 5, for example. A configuration in which the refrigerant circuit is switched from the first heating mode to the second heating mode can be employed.

  As another example, the refrigerant circuit from the first heating mode to the second heating mode when the refrigerant pressure on the compressor suction side in the first heating mode is lower than a predetermined pressure as in the invention described in claim 6. It is possible to adopt a configuration for switching between.

  As another example, as in the invention described in claim 7, when the refrigerant temperature on the compressor discharge side in the first heating mode is higher than a predetermined temperature, the refrigerant circuit is switched from the first heating mode to the second heating mode. A configuration for switching can be employed.

  Moreover, as a heat radiator of Claim 1, the structure which heat-exchanges the high temperature refrigerant | coolant of a high voltage | pressure side and the ventilation air after passing through an evaporator is also employ | adopted via the liquid like invention of Claim 8. Is possible. That is, it is arranged in the air conditioning case (11) on the downstream side of the air flow of the evaporator (13), and the liquid heated by the liquid heating means (62) flows through the inside, and the heated liquid and the evaporator ( 13) The first radiator (61) for exchanging heat with the blown air after passing to dissipate the liquid, and the second radiator (for dissipating the refrigerant by exchanging heat between the high-temperature refrigerant on the high-pressure side and the liquid) 81) can be employed.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a whole block diagram which shows the refrigerant circuit at the time of the air_conditioning | cooling mode of the vehicle air conditioner in 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the dehumidification heating mode of the vehicle air conditioner in 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 1st heating mode of the vehicle air conditioner in 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 2nd heating mode of the vehicle air conditioner in 1st Embodiment. It is a block diagram of the electric control part in a 1st embodiment. It is a flowchart of the air-conditioning control which the air-conditioning control apparatus 40 in FIG. 5 performs. It is a Mollier diagram which shows the refrigerant | coolant change at the time of the 2nd heating mode of 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 2nd heating mode of the vehicle air conditioner in 2nd Embodiment. It is a Mollier diagram which shows the refrigerant | coolant change at the time of the 2nd heating mode of 2nd Embodiment. (A), (b) is a figure which shows the calculation result of the compressor motive power with respect to the inlet air temperature of the radiator 14 in 2nd Embodiment, and the emitted-heat amount (heating capability) of the radiator 14, respectively. It is a whole block diagram which shows the refrigerant circuit at the time of the 2nd heating mode of the vehicle air conditioner in 3rd Embodiment. It is a Mollier diagram which shows the refrigerant | coolant change at the time of the 2nd heating mode of 3rd Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 2nd heating mode of the vehicle air conditioner in 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings for the sake of simplicity (first embodiment).
The present embodiment is an air conditioner for a vehicle that is mounted on an electric vehicle (EV) that obtains driving force for traveling from the electric motor for traveling. 1 to 4 show the overall configuration of this vehicle air conditioner.

  As shown in FIGS. 1 to 4, the vehicle air conditioner 1 of the present embodiment includes an indoor air conditioning unit 10 and a refrigeration cycle 20. 1 to 4 show the refrigerant flow when the operation mode of the refrigeration cycle 20 is the cooling mode, the dehumidifying heating mode, the first heating mode, and the second heating mode, respectively, in the vehicle air conditioner 1 of the present embodiment. ing.

  The indoor air conditioning unit 10 is disposed inside the instrument panel (instrument panel) at the foremost part of the vehicle interior, and houses a blower 12, an evaporator 13, a radiator 14 and the like in an air conditioning case 11 forming an outer shell thereof. Is.

  The air conditioning case 11 forms an air passage for blown air that is blown into the vehicle compartment, and has a certain degree of elasticity and is formed of a resin that is excellent in strength. On the most upstream side of the blast air flow in the air conditioning case 11, an inside air introduction port 11a and an outside air introduction port 11b for introducing inside air (vehicle compartment air) and outside air (vehicle compartment outside air) into the air conditioning case 11, and the air volume of the inside air There is provided an inside / outside air switching door 15 for changing the air volume ratio with the outside air volume. The inside / outside air switching door 15 is driven by an electric actuator for the inside / outside air switching door.

  On the downstream side of the air flow of the inside / outside air switching door 15, a blower 12 that blows air sucked through the inside air introduction port 11 a and the outside air introduction port 11 b toward the vehicle interior is arranged. The blower 12 is an electric blower that drives a centrifugal multiblade fan with an electric motor.

  An evaporator 13 is disposed on the downstream side of the air flow of the blower 12. The evaporator 13 is a cooling heat exchanger that cools the blown air by exchanging heat between the low-pressure refrigerant on the low-pressure side that flows through the evaporator 13 and the blown air.

  On the downstream side of the air flow of the evaporator 13, an air passage such as a heating cold air passage 16 and a heating cold air bypass passage 17 through which air passes through the evaporator 13 is formed by a partition wall 11c. Further, on the downstream side of these air flows, a mixing space 18 is formed for mixing the air flowing out from the heating cold air passage 16 and the heating cold air bypass passage 17.

  A radiator 14 is disposed in the heating cool air passage 16. The radiator 14 is a heat exchanger for heating that heats the air that has passed through the evaporator 13 by exchanging heat between the high-temperature refrigerant on the high-pressure side and the air that has passed through the evaporator 13. The radiator 14 functions as a condenser that condenses the refrigerant, as will be described later.

  On the other hand, the heating / cooling air bypass passage 17 is an air passage for guiding the air that has passed through the evaporator 13 to the mixing space 18 without passing through the radiator 14. Therefore, the temperature of the blown air mixed in the mixing space 18 varies depending on the air volume ratio of the air passing through the heating cool air passage 16 and the air passing through the heating cold air bypass passage 17.

  Therefore, in the present embodiment, the cool air that flows into the heating cool air passage 16 and the heating cool air bypass passage 17 on the downstream side of the air flow of the evaporator 13 and on the inlet side of the heating cool air passage 16 and the heating cool air bypass passage 17. An air mix door 19 for continuously changing the air volume ratio is provided.

  Therefore, the air mix door 19 constitutes a temperature adjusting means for adjusting the air temperature in the mixing space 18 (the temperature of the blown air blown into the vehicle interior). The air mix door 19 is driven by an electric actuator for the air mix door.

  Furthermore, the blower outlet (not shown) which blows off the temperature-adjusted blast air from the mixing space 18 to the vehicle interior which is a space for air conditioning is arrange | positioned in the most downstream part of the blast air flow of the air-conditioning case 11. Specifically, the air outlet includes a face air outlet that blows air-conditioned air toward the upper body of the passenger in the passenger compartment, a foot air outlet that blows air-conditioned air toward the feet of the passenger, and an inner surface of the front window glass of the vehicle. A defroster outlet for blowing air conditioned air is provided.

  In addition, on the air flow upstream side of the face outlet, the foot outlet and the defroster outlet, a face door for adjusting the opening area of the face outlet, a foot door for adjusting the opening area of the foot outlet, and a defroster outlet, respectively. A defroster door (both not shown) for adjusting the opening area is disposed.

  These face doors, foot doors, and defroster doors constitute an outlet mode door for switching the outlet mode, and are linked to an electric actuator for driving the outlet mode door via a link mechanism (not shown). And rotated.

  Next, the refrigeration cycle 20 of this embodiment will be described.

  The refrigeration cycle 20 includes a compressor 21, an outdoor heat exchanger 22, a heating throttle 23, a cooling throttle 24, an accumulator 25, and the like, in addition to the evaporator 13 and the radiator 14 described above. Each of these devices is connected by a refrigerant pipe that forms a refrigerant flow path. The refrigeration cycle 20 employs a normal chlorofluorocarbon refrigerant as the refrigerant, and constitutes a subcritical refrigeration cycle in which the refrigerant pressure on the high pressure side does not exceed the critical pressure of the refrigerant. Furthermore, this refrigerant is mixed with refrigerating machine oil for lubricating the compressor 21, and this refrigerating machine oil circulates in the cycle together with the refrigerant.

  In this embodiment, specifically, the compressor 21, the radiator 14, the heating throttle 23, the outdoor heat exchanger 22, the cooling throttle 24, the evaporator 13, the accumulator 25, and the compressor 21 are connected in series in this order. The refrigerant circuit is configured.

  The compressor 21 is arranged in the engine room, sucks refrigerant in the refrigeration cycle 20, compresses and discharges it, and drives a fixed capacity type compression mechanism with a fixed discharge capacity by an electric motor (not shown). It is configured as an electric compressor. The refrigerant discharge capacity of the compressor 21 is controlled by controlling the rotation speed of the electric motor by the air conditioning controller. As the fixed capacity compression mechanism, various compression mechanisms such as a scroll compression mechanism and a vane compression mechanism can be employed.

  The radiator 14 is a condenser that radiates and condenses the refrigerant by heat exchange between the high-pressure side high-temperature refrigerant discharged from the compressor 21 and the blown air.

  The heating throttle 23 is a heating decompression unit that decompresses and expands the refrigerant flowing out of the radiator 14 mainly in the first heating mode and the second heating mode. As the heating throttle 23, a fixed throttle such as a capillary tube or an orifice, or a variable throttle mechanism capable of adjusting the throttle passage area can be employed.

  The outdoor heat exchanger 22 is disposed in the engine room, and exchanges heat between the refrigerant circulating in the interior and the air outside the vehicle (outside air) blown from the outdoor blower fan 22a. The evaporator 13 is connected to the refrigerant outlet side of the outdoor heat exchanger 22 via a cooling throttle 24.

  The cooling throttle 24 is a cooling decompression unit that decompresses and expands the refrigerant flowing out of the radiator 14 mainly in the cooling mode. As the cooling throttle 24, a fixed throttle such as a capillary tube or an orifice, or a variable throttle capable of adjusting the throttle passage area can be adopted.

  The evaporator 13 absorbs and evaporates the refrigerant by heat exchange between the low-temperature side low-temperature refrigerant after passing through the cooling throttle 24 and the blown air.

  The accumulator 25 is a low-pressure side gas-liquid separator that separates the gas-liquid refrigerant flowing into the accumulator 25 and stores excess refrigerant. The refrigerant suction side of the compressor 21 is connected to the gas phase refrigerant outlet of the accumulator 25.

  Further, the refrigerant circuit opens and closes the first bypass flow path 26 and the first bypass flow path 26 that guide the refrigerant flowing out of the radiator 14 to the outdoor heat exchanger 22 by bypassing the heating throttle 23. A first electromagnetic valve 27 as an opening / closing means is provided.

  In addition, the refrigerant flowing out of the outdoor heat exchanger 22 bypasses both the cooling throttle 24 and the evaporator 13 and leads to the accumulator 25, and the second bypass flow path 28 is opened and closed. An electric three-way valve 29 as an opening / closing means is provided. The electric three-way valve 29 has a refrigerant inlet side connected to the outdoor heat exchanger 22, one refrigerant outlet side is connected to a refrigerant flow path toward the evaporator 13, and the other refrigerant outlet side is a second bypass flow path 28. Is a switching means for switching between the two refrigerant flow paths on the refrigerant outlet side.

  In addition, the refrigerant after passing through the heating throttle 23 bypasses the outdoor heat exchanger 22 and leads to the second bypass passage 28, and as opening / closing means for opening and closing the third bypass passage 30 The second electromagnetic valve 31 is provided. Although the downstream end of the third bypass flow path 30 is connected to the second bypass flow path 28, it is not the second bypass flow path 28 but the refrigerant flow path between the evaporator 13 and the accumulator 25. It may be connected.

  The refrigeration cycle 20 having such a configuration includes a first electromagnetic valve 27, a second electromagnetic valve 31, and an electric three-way valve 29, and a cooling mode refrigerant circuit, a dehumidifying heating mode refrigerant circuit, a first heating mode refrigerant circuit, Switching to any one of the refrigerant circuits in the second heating mode is possible. Accordingly, the first solenoid valve 27, the second solenoid valve 31, and the electric three-way valve 29 constitute a refrigerant circuit switching means.

  In the cooling mode shown in FIG. 1, the first electromagnetic valve 27 is opened, and the electric three-way valve 29 closes the second bypass flow path 28 side and opens the evaporator 13 side. As indicated by the arrows in the figure, the refrigerant circulates in the order of the radiator 14 → the first electromagnetic valve 27 → the outdoor heat exchanger 22 → the electric three-way valve 29 → the cooling throttle 24 → the evaporator 13 → the accumulator 25 → the compressor 21. A circuit is constructed.

  In the dehumidifying and heating mode shown in FIG. 2, both the first electromagnetic valve 27 and the second electromagnetic valve 31 are closed, and the electric three-way valve 29 closes the second bypass flow path 28 side and opens the evaporator 13 side. As shown by the arrows in the figure, the refrigerant discharged from the compressor 21 is the radiator 14 → the heating throttle 23 → the outdoor heat exchanger 22 → the electric three-way valve 29 → the cooling throttle 24 → the evaporator 13 → the accumulator 25. → A refrigerant circuit that circulates in order from the suction side of the compressor 21 is formed.

  In the first heating mode shown in FIG. 3, both the first electromagnetic valve 27 and the second electromagnetic valve 31 are closed, and the electric three-way valve 29 opens the second bypass flow path 28 side and closes the evaporator 13 side. As indicated by the arrows in the figure, the refrigerant discharged from the compressor 21 flows in the order of the radiator 14 → the heating throttle 23 → the outdoor heat exchanger 22 → the electric three-way valve 29 → the accumulator 25 → the suction side of the compressor 21. A circulating refrigerant circuit is configured.

  In the second heating mode shown in FIG. 4, the first solenoid valve 27 is closed and the second solenoid valve 31 is opened, so that the refrigerant discharged from the compressor 21 is discharged from the radiator 14 → as indicated by the arrow in the figure. A refrigerant circuit that circulates in the order of the heating throttle 23 → the second electromagnetic valve 31 → the accumulator 25 → the suction side of the compressor 21 is configured.

  Next, the electric control unit of this embodiment will be described with reference to FIG. FIG. 5 is a block diagram of the electric control unit of the present embodiment.

  The air conditioning control device 40 as a control means is composed of a well-known microcomputer including a CPU, ROM, RAM, etc. and its peripheral circuits, and performs various calculations and processing based on an air conditioning control program stored in the ROM. Controls the operation of equipment connected to the output side. The equipment connected to the output side includes the blower 12, the compressor 21, the outdoor blower fan 22a, the electric three-way valve 29, the first solenoid valve 27, the second solenoid valve 31, the inside / outside air switching door electric actuator 51, air Examples thereof include an electric actuator 52 for a mixed door and an electric actuator 53 for a blowing mode door.

  Further, detection signals from the respective sensor groups are input to the input side of the air conditioning control device 40. The sensor group includes an inside air sensor 41 that detects the vehicle interior temperature Tr, an outside air sensor 42 (outside air temperature detection means) that detects the outside air temperature Tam, a solar radiation sensor 43 that detects the amount of solar radiation Ts in the vehicle interior, and the compressor 21. A discharge temperature sensor 44 (discharge temperature detection means) for detecting the discharge refrigerant temperature Td, a discharge pressure sensor 45 (discharge pressure detection means) for detecting the discharge side refrigerant pressure (high pressure side refrigerant pressure) Pd of the compressor 21, and the evaporator 13 An evaporator temperature sensor 46 (evaporator temperature detecting means) for detecting an evaporator blown air temperature (evaporator temperature) TE, which is an air temperature blown from the air, and an intake temperature sensor 47 for detecting an intake refrigerant temperature Ts of the compressor 21. (Suction temperature detection means), a suction pressure sensor 48 (suction pressure detection means) for detecting the suction side refrigerant pressure (low pressure side refrigerant pressure) Ps of the compressor 21, and a window glass near the vehicle interior A humidity sensor for detecting the relative humidity of the room air, the window glass near the temperature sensor for detecting the temperature of the room air of the window glass near, and the window glass surface temperature sensor for detecting the window glass surface temperature and the like.

  By the way, in this embodiment, as shown in FIGS. 1-4, the discharge temperature sensor 44 is arrange | positioned at the refrigerant | coolant flow downstream of the compressor 21, and the refrigerant | coolant flow upstream of the radiator 14, and the discharge pressure sensor 45 is heat dissipation. The suction temperature sensor 47 is disposed on the downstream side of the container 14 and on the upstream side of the first bypass flow path 26, and is disposed on the downstream side of the second bypass flow path 28 with respect to the connection portion with the third bypass flow path 30. The suction pressure sensor 48 is disposed downstream of the accumulator 25 and downstream of the compressor 21.

  Furthermore, operation signals from various air conditioning operation switches provided on the operation panel 50 disposed near the instrument panel in the front of the vehicle interior are input to the input side of the air conditioning control device 40. As various air conditioning operation switches, the operation switch of the vehicle air conditioner 1, the operation switch of the compressor that selects the operation / stop of the compressor 21, the operation mode changeover switch, the air outlet mode changeover switch, the air volume setting of the blower 12 Examples include a switch, a vehicle interior temperature setting switch, and an economy switch that outputs a command giving priority to power saving of the refrigeration cycle.

  Next, the operation of the vehicle air conditioner 1 of the present embodiment will be described.

  As described below, the air conditioning control device 40 controls the control target values of various devices based on the air conditioning heat load, for example, the air flow rate of the blower 12, the suction port mode, the air outlet mode, the opening degree of the air mix door 19, and the refrigeration cycle 20. Determine the operation mode. And various apparatuses operate | move by outputting the control signal according to the determined content with respect to various apparatuses.

  In FIG. 6, the flowchart of the air-conditioning control which the air-conditioning control apparatus 40 performs is shown. Hereinafter, the operation mode determination process will be mainly described.

  In step S1, a vehicle environmental condition signal used for air conditioning control, that is, a detection signal of the above-described sensor group and an operation signal of the operation panel 50 are read, and the process proceeds to step S2.

  In step S2, it is determined whether or not the compressor 21 is in an operating state. At this time, when the stop of the compressor 21 is selected by the operation switch of the compressor 21 or when the air-conditioning control device 40 controls the stop of the compressor 21, a NO determination is made and the process returns to step S1. . On the other hand, if the compressor 21 is in an operating state, a YES determination is made and the process proceeds to step S3.

In step S3, a target blown air temperature TAO of the vehicle compartment blown air is calculated. The target blown air temperature TAO is calculated based on the air-conditioning heat load, that is, the vehicle interior set temperature and the vehicle environmental conditions such as the vehicle interior temperature, and specifically, is calculated by the following formula F1.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × Ts + C (F1)
Here, Tset is the vehicle interior temperature set by the vehicle interior temperature setting switch, Tr is the vehicle interior temperature detected by the internal air sensor 41 (inside air temperature), Tam is the outside air temperature detected by the outside air sensor 42, and Ts is This is the amount of solar radiation detected by the solar radiation sensor 43. Kset, Kr, Kam, Ks are control gains, and C is a correction constant.

  Subsequently, in step S4, the refrigeration cycle 20 is based on the target blown air temperature TAO, the intake air temperature from the inside / outside air introduction ports 11a, 11b, the temperature and relative humidity of the vehicle interior air near the window glass, the window glass surface temperature, and the like. Is determined as any one of the cooling mode, the dehumidifying heating mode, and the heating mode.

  In addition to the operation mode, the control target values of various devices such as the target rotation speed of the compressor 21, the opening degree of the air mix door 19, and the air blowing amount of the outdoor blower fan 22a are set based on the target blown air temperature TAO. decide. Moreover, in this embodiment, when determining the target rotation speed of the compressor 21, the discharge temperature of the compressor 21 is set to be less than a predetermined temperature for the purpose of protecting the various devices constituting the refrigeration cycle 20 from heat. In addition, the target rotational speed of the compressor 21 is reduced and corrected (power save control of the compressor 21).

  Subsequently, in step S5, it is determined whether or not the operation mode determined in step S4 is the heating mode. At this time, if it is the cooling mode or the dehumidifying heating mode, a NO determination is made, the process proceeds to step S6, and it is further determined whether or not the operation mode determined in step S4 is the cooling mode. At this time, if the determined operation mode is the dehumidifying heating mode, the process proceeds to step S7, and if the determined operation mode is the cooling mode, the process proceeds to step S8.

  In step S7, a control signal for setting the operation mode to the dehumidifying heating mode is output to each actuator. Specifically, a control signal is output so that both the first electromagnetic valve 27 and the second electromagnetic valve 31 are closed. In addition, a control signal is output to the electric three-way valve 29 so that the second bypass flow path 28 side is closed and the evaporator 13 side is opened. Further, a control signal for fully opening the heating cool air passage 16 is output to the electric actuator 52 for the air mix door.

  Thereby, the air mix door 19 will be in the position which makes the cold wind path 16 for heating fully open, and the heating dehumidification mode shown in FIG. 2 will be performed. In this heating dehumidification mode, as described above, a refrigerant circuit for circulating the refrigerant is configured as indicated by the arrows in the figure. In this refrigerant circuit, the high-pressure side high-temperature refrigerant dissipates heat in the radiator 14, and the low-pressure side low-temperature refrigerant absorbs heat in the evaporator 13, so that the blown air from the blower 12 is dehumidified and dehumidified in the evaporator 13. The blown air is heated by the radiator 14 and the heated blown air is blown out from a blower outlet (not shown).

  Here, when variable throttles are used as the heating throttle 23 and the cooling throttle 24, the air conditioning control device 40 controls the opening degrees of the heating throttle 23 and the cooling throttle 24 according to the target blown air temperature TAO. . For example, when the air temperature after passing through the radiator 14 is lowered, the heating throttle 23 is fully opened, and the cooling throttle 24 is not fully opened but a predetermined throttle opening. As a result, the refrigerant radiates heat in both the radiator 14 and the outdoor heat exchanger 22, and the amount of heat radiated in the radiator 14 is reduced as compared with the case where the radiator 14 radiates heat alone. The temperature can be lowered.

  On the other hand, when the air temperature after passing through the radiator 14 is increased, the heating throttle 23 is set to a predetermined throttle opening, not fully opened, and the cooling throttle 24 is fully opened. As a result, the refrigerant absorbs heat in both the evaporator 12 and the outdoor heat exchanger 22, and the amount of heat absorption increases as compared with the case where the evaporator 12 absorbs heat alone, so that the heat dissipation amount in the radiator 14 can be increased. The air temperature after 14 passes can be made high.

  When a fixed throttle is used as the heating throttle 23 and the cooling throttle 24, the outdoor heat exchanger 22 acts as a radiator, a heat absorber, or a simple refrigerant passage depending on the outside air temperature.

  In step S8, a control signal is output to each actuator in order to set the operation mode to the cooling mode. Specifically, a control signal is output to the first electromagnetic valve 27 so as to open. In addition, a control signal is output to the electric three-way valve 29 so that the second bypass flow path 28 side is closed and the evaporator 13 side is opened. Further, a control signal for fully closing the heating cold air passage 16 is output to the electric actuator 52 for the air mix door.

  As a result, the air mix door 19 is in a position where the cool air passage 16 for heating is fully closed, and the cooling mode shown in FIG. 1 is executed. In this cooling mode, as described above, a refrigerant circuit that circulates the refrigerant is configured as shown by the arrows in the figure. In this refrigerant circuit, the high-temperature refrigerant on the high-pressure side dissipates heat in the outdoor heat exchanger 22, and the evaporator 13 Since the low-temperature refrigerant on the low-pressure side absorbs heat, the blower air from the blower 12 is cooled by the evaporator 13, and the blown air after cooling is blown out from the blower outlet (not shown).

  In step S5, if the operation mode determined in step S4 is the heating mode, a YES determination is made, and the process proceeds to step S9.

  In step S9, determination for selecting the first heating mode and the second heating mode is performed. Specifically, it is determined whether or not the outside air temperature Tam is higher than a predetermined temperature T1. The predetermined temperature T1 is set on the basis of the outside air temperature when the heating capacity cannot be sufficiently secured when the first heating mode is executed, and is set to −30 ° C., for example.

  When the outside air temperature Tam is higher than the predetermined temperature T1 and heating in the first heating mode is possible, the process proceeds to step S10, and a control signal for executing the first heating mode is output to each actuator. Specifically, a control signal is output so that both the first electromagnetic valve 27 and the second electromagnetic valve 31 are closed. Further, a control signal is output so that the second bypass flow path 28 side is opened with respect to the electric three-way valve 29 and the evaporator 13 side is closed. Further, a control signal for fully opening the heating cool air passage 16 is output to the electric actuator 52 for the air mix door.

  As a result, the air mix door 19 is in a position where the heating air passage 16 is fully opened, and the first heating mode shown in FIG. 3 is executed. In the first heating mode, a refrigerant circuit that circulates the refrigerant is configured as indicated by the arrows in the figure. In this refrigerant circuit, the high-temperature refrigerant on the high-pressure side is radiated by the radiator 14, and the low-pressure side is discharged by the outdoor heat exchanger 22. Since the low-temperature refrigerant absorbs heat, the blown air after passing through the evaporator 13 is heated by the radiator 14, and the heated blown air is blown out from a blower outlet (not shown).

  On the other hand, if the outside air temperature Tam is lower than the predetermined temperature T1 in step S9 and sufficient heating capacity cannot be obtained in the first heating mode, the process proceeds to step S11.

  In step S11, a control signal for executing the second heating mode is output to each actuator. Specifically, a control signal is output so as to be closed with respect to the first electromagnetic valve 27, and a control signal is output so as to be opened with respect to the second electromagnetic valve 31. Further, a control signal is output so as to stop the blower fan 22a, and a control signal for fully opening the heating cool air passage 16 is output to the air mix door electric actuator 52.

  Thereby, the air mix door 19 will be in the position which makes the heating air channel | path 16 fully open, the ventilation fan 22a will stop, and the 2nd heating mode shown in FIG. 4 will be performed. In this second heating mode, a refrigerant circuit that circulates the refrigerant as shown by the arrows in the drawing, that is, the refrigerant discharged from the compressor 21 flows into the radiator 14 and the refrigerant flowing out of the radiator 14 is used as the heating throttle. After the pressure is reduced by the refrigerant 23, a refrigerant circuit is configured that bypasses both the outdoor heat exchanger 22 and the evaporator 13 and leads to the suction side of the compressor 21.

  Accordingly, in the second heating mode, the high-pressure refrigerant on the high-pressure side after discharge from the compressor 21 exchanges heat with the blown air that has passed through the evaporator 13 and dissipates heat. By this heat radiation, the blown air passing through the radiator 14 is heated, and the heated blown air is blown out from the blower outlet (not shown) into the vehicle interior. Then, the refrigerant flowing out of the radiator 14 is decompressed by the heating throttle 23 and then sucked into the compressor 21 via the second electromagnetic valve 31 and the accumulator 25.

  Here, the Mollier diagram which shows the refrigerant | coolant change at the time of 2nd heating mode in FIG. 7 is shown. In the second heating mode, as shown in FIG. 7, the high-temperature gas-phase refrigerant (hot gas) discharged from the compressor 21 dissipates heat in the radiator 14, thereby partially condensing into a gas-liquid two-phase state. The refrigerant in the gas-liquid two-phase state is decompressed by the heating throttle 23 to form a hot gas cycle in which the gas-phase state is obtained. In this hot gas cycle, unlike the first heating mode of the heat pump cycle, there is no heat absorption of the refrigerant in the outdoor heat exchanger 22, so the heat release amount of the radiator 14 is determined by the compression work amount of the compressor 21. . In the present embodiment, the refrigerant is in a gas-liquid two-phase state in the radiator 14, but remains in a gas phase state depending on the physical properties of the refrigerant used.

  As described above, in the present embodiment, when the outside air temperature Tam is higher than the predetermined temperature T1 by the air conditioning control device 40, the first heating mode by the heat pump cycle is executed, and the outside air temperature Tam is higher than the predetermined temperature T1. In the case of a low outside air temperature, the mode is switched to the second heating mode in which the blown air is heated using the hot gas discharged from the compressor flowing into the radiator 14 as a heat source.

  And in this 2nd heating mode, since a refrigerant | coolant is not flowed through the outdoor heat exchanger 22, and an outdoor heat exchanger is not made to act as a heat sink, the outdoor heat exchanger 22 does not form frost, and removal of the outdoor heat exchanger 22 is carried out. Frost operation becomes unnecessary. Therefore, according to the present embodiment, it is possible to perform a continuous heating operation when the outside air is extremely cold, and it is possible to ensure the heating capacity.

  In the first heating mode, the refrigerant pressure is reduced by the heating restrictor 23 due to the heat absorption in the outdoor heat exchanger 22 as the outside air temperature decreases, and as a result, the suction pressure of the compressor 21 is reduced. Since it decreases and the compression ratio increases, the discharge refrigerant temperature of the compressor 21 rises. For this reason, if the first heating mode is executed when the outside air is at a very low temperature, the discharge refrigerant temperature of the compressor 21 exceeds a predetermined temperature, so that power save control is performed to keep the rotation speed of the compressor 21 low for equipment protection. As a result, the heating capacity is substantially reduced.

  In contrast, in the second heating mode, since the refrigerant is not absorbed by the outdoor heat exchanger 22, it is possible to suppress a decrease in the suction pressure of the compressor 21 as compared with the first heating mode under the same outdoor temperature. The rise in the refrigerant temperature discharged from the compressor 21 can be suppressed. For this reason, even if the second heating mode is executed when the outside air is at a very low temperature, the power saving control function of the compressor 21 can be avoided.

  Incidentally, a refrigeration cycle in which heating (hot gas heating) is performed by causing the evaporator to dissipate heat by flowing high-pressure high-temperature gas-phase refrigerant (hot gas) after discharge from the compressor into the evaporator. As is well known, in this known refrigeration cycle, since the high-pressure refrigerant discharged from the compressor flows into the evaporator, the evaporator needs to have a high-pressure resistant structure that can withstand the high-pressure refrigerant. On the other hand, in this embodiment, since the high pressure refrigerant is not allowed to flow into the evaporator 13, the high pressure resistant structure of the evaporator 13 can be eliminated. The same applies to the following embodiments.

(Second Embodiment)
The present embodiment is a vehicle air conditioner mounted on a so-called hybrid vehicle (HV) that obtains driving force for vehicle travel from an internal combustion engine (engine) and a travel electric motor. A hot water heater core 61 is added to the indoor air conditioning unit 10.

  In FIG. 8, the whole structure of the vehicle air conditioner of this embodiment is shown. Specifically, the vehicle air conditioner 1 includes a cooling water circuit 63 in which engine cooling water circulates between a heater core 61 and an engine (EG) 62. The heater core 61 is an air heating unit that heats blown air using engine coolant as a heat source. The heater core 61 is disposed on the air flow downstream side of the evaporator 13 in the air conditioning case 11 and on the air flow upstream side of the radiator 14.

  Therefore, the radiator 14 is arranged in the air conditioning case 11 on the downstream side of the air flow from the heater core 61, and the blown air after passing through the heater core 61 flows in.

  In the present embodiment, under the condition that the first heating mode is selected, when the cooling water temperature of the heater core 61 is lower than the predetermined temperature, the heating in the first heating mode is performed, and the cooling water of the heater core 61 is When the temperature is higher than a predetermined temperature, heating by the heater core 61 is performed.

  In the present embodiment, the blower air is heated by the heater core 61 in the second heating mode. Specifically, when the air conditioning control device 40 executes the second heating mode as the operation mode of the refrigeration cycle 20, if the engine 62 is stopped and the coolant temperature is lower than a predetermined temperature, A request signal is output to the engine control device. As a result, the engine 62 is operated to increase the coolant temperature, and the blower air is heated by the heater core 61. Therefore, the heating capacity of the entire air conditioner in the second heating mode is the sum of the heat dissipation amount of the radiator 14 and the heat dissipation amount of the heater core 61.

  Note that, unlike the present embodiment, the heater core 61 can be arranged on the downstream side of the air flow of the radiator 14. However, as shown in FIG. 9, the heater core 61 is arranged on the upstream side of the air flow of the radiator 14 as compared with the case where the heater core 61 is arranged on the downstream side of the air flow of the radiator 14 as in this embodiment. As described above, the heat dissipation amount of the radiator 14 can be increased.

  Here, in FIG. 9, the Mollier diagram which shows the refrigerant | coolant change at the time of 2nd heating mode is shown. In the hot gas cycle in the second heating mode, the cycle balance is determined by the work of the compressor 21 and the performance of the radiator 14. In this hot gas cycle, when the inlet air temperature of the radiator 14 rises from T01 to T02 (not shown), as shown in FIG. 9, the refrigerant temperature on the high-pressure side is changed from T11 to T12 in order to secure the heat radiation amount. (The refrigerant pressure on the high pressure side increases from P1 to P2), and as a result, the compression work of the compressor 21 increases and the heat dissipation of the radiator 14 increases from Q1 to Q2. Balance.

  Therefore, when the heat dissipation amount of the heater core 61 is the same, when the heater core 61 is arranged on the air flow upstream side of the radiator 14 by arranging the heater core 61 on the air flow upstream side of the radiator 14 as in the present embodiment. Compared with, the heating capacity of the radiator 14 can be improved.

  Further, when comparing the first heating mode and the second heating mode of the present embodiment, as shown in FIGS. 10A and 10B, the second heating mode is more radiator than the first heating mode. The heating capacity of 14 may be high. 10A and 10B are diagrams showing calculation results of the compressor power and the heat radiation amount (heating capacity) of the radiator 14 with respect to the inlet air temperature of the radiator 14, respectively.

  When the first heating mode is executed at a very low outside air temperature, as shown in FIG. 10A, the compressor power increases as the inlet air temperature of the radiator 14 increases, but the inlet air temperature is higher than the predetermined temperature Tx. However, when the temperature is high, the power of the compressor does not exceed a predetermined power value by the power save control, and tends to be constant at the predetermined power value.

  Therefore, in the first heating mode, as shown in FIG. 10B, the heat dissipation amount of the radiator 14, that is, the heating capacity of the radiator 14, is also in the region where the inlet air temperature is higher than the predetermined temperature Tx. The predetermined heating capacity Qx is constant, and a heating capacity higher than the predetermined heating capacity Qx cannot be obtained.

  On the other hand, when the second heating mode is executed when the outside air is at a very low temperature, as described above, the power saving control can be avoided, and as shown in FIG. 10A, as the inlet air temperature of the radiator 14 increases. The compressor power tends to continue to rise. For this reason, as shown in FIG.10 (b), when the inlet air temperature of the radiator 14 is more than predetermined temperature Ta degree C, the heating capability of the radiator 14 will result in exceeding the heating capability at the time of 1st heating mode. .

(Third embodiment)
In FIG. 11, the whole structure of the vehicle air conditioner of this embodiment is shown. In the present embodiment, a second heating throttle 71 for reducing the pressure of the refrigerant discharged from the compressor is added to the vehicle air conditioner of the first embodiment. In addition, you may add this 2nd aperture_diaphragm | restriction 71 with respect to the vehicle air conditioner of 2nd Embodiment.

  Specifically, in addition to the configuration of the first embodiment, the vehicle air conditioner 1 includes a second heating throttle 71 that decompresses the refrigerant after discharging the compressor 21 and before flowing into the radiator 14, A fourth bypass passage 72 through which the refrigerant bypasses the heating restrictor 71 and an electromagnetic valve 73 as an opening / closing means for opening and closing the fourth bypass passage 72 are provided. A fixed throttle or a variable throttle can be adopted as the second heating throttle 71.

  Further, unlike the first embodiment, the third bypass flow path 30 of the present embodiment bypasses the refrigerant after passing the radiator 14 between the heating throttle 23 and the outdoor heat exchanger 22, so that the second bypass flow It leads to the road 28. In addition, the heating throttle 23 described in the first embodiment is the first heating throttle 23 in the present embodiment.

  The air conditioning control device 40 outputs a control signal to open the electromagnetic valve 73 in the cooling mode, the dehumidifying heating mode, and the first heating mode. Thereby, the refrigerant circuit at the time of air_conditioning | cooling mode, dehumidification heating mode, and 1st heating mode becomes a structure similar to 1st Embodiment.

  On the other hand, the air-conditioning control device 40 outputs a control signal so as to close the electromagnetic valve 73 in the second heating mode. Thus, in the second heating mode, the refrigerant discharged from the compressor 21 is decompressed by the second heating throttle 71 and then flows into the radiator 14 as indicated by the arrows in FIG. A refrigerant circuit is configured in which the refrigerant flowing out of the refrigerant 14 bypasses the first heating throttle 23, the outdoor heat exchanger 22, and the evaporator 13 and is led to the suction side of the compressor 21.

  FIG. 12 is a Mollier diagram showing refrigerant changes during the second heating mode of the present embodiment. In the present embodiment, since the refrigerant discharged from the compressor 21 is depressurized by the second heating throttle 71 before flowing into the radiator 14, the inlet refrigerant temperature T <b> 22 of the radiator 14 is changed after the compressor 21 is discharged. It becomes lower than the refrigerant temperature T21.

  For this reason, compared with the time of the 2nd heating mode of 1st Embodiment shown in FIG. 7, when the refrigerant | coolant temperature after discharge of the compressor 21 is the same, the inlet-side refrigerant | coolant temperature of the radiator 14 is low, and the ventilation which passes the radiator 14 is passed. Since the temperature difference with air is reduced, the hot gas cycle shown in FIG. 12 is more balanced than the hot gas cycle shown in FIG. 7 in an attempt to increase the temperature difference.

  Therefore, according to the present embodiment, the compression work of the compressor 21 can be increased and higher heating capacity can be obtained than in the second heating mode of the first embodiment.

  However, the present embodiment includes the second heating throttle 71, the fourth bypass flow path 72, and the electromagnetic valve 73, and has more components of the refrigeration cycle 20 than the first embodiment. From the viewpoint of the simplification of the configuration 20, the first embodiment is preferable to the present embodiment.

(Fourth embodiment)
In 1st Embodiment, although the heat radiator 14 which heat-exchanges a high temperature refrigerant | coolant and ventilation air as liquid radiator which radiates a high temperature refrigerant | coolant without passing liquids, such as an engine cooling water, was adopted in this embodiment, A radiator that exchanges heat between the high-temperature refrigerant and the blown air through the engine coolant is employed.

  In FIG. 13, the whole structure of the vehicle air conditioner of this embodiment is shown. In the present embodiment, the radiator 14 is changed to a water-refrigerant heat exchanger 81 with respect to the configuration shown in FIG. 2 described in the second embodiment, and other configurations are the same as those in the second embodiment. .

  The heater core 61 of the present embodiment is disposed in the air conditioning case 11 on the downstream side of the air flow of the evaporator 13, and exchanges heat between the engine cooling water and the blown air that has passed through the evaporator 13, thereby cooling the engine cooling water. It is the 1st heat radiator which radiates heat.

  The water-refrigerant heat exchanger 81 is connected to the downstream side of the compressor 21 and the upstream side of the heating throttle 23 in the refrigerant circuit, and the high-temperature refrigerant and engine coolant on the high-pressure side after the compressor 21 is discharged. It is the 2nd heat radiator which is made to heat-exchange and radiates a refrigerant | coolant.

  The vehicle air conditioner having such a configuration operates in the same manner as the second embodiment because the radiator 14 is merely changed to the water-refrigerant heat exchanger 81 with respect to the second embodiment. Incidentally, in the dehumidifying heating mode, the first heating mode, and the second heating mode, the engine cooling water is heated by the heat radiation of the refrigerant in the water / refrigerant heat exchanger 81, and the evaporator 13 is discharged by the heat radiation of the engine cooling water in the heater core 61. The blown air after passing is heated.

  Accordingly, a radiator that radiates the refrigerant by exchanging heat between the high-temperature refrigerant on the high-pressure side and the blown air after passing through the evaporator 13 through the engine cooling water by both the water-refrigerant heat exchanger 81 and the heater core 61. It can be said that it is composed. As described above, as a heat radiator that dissipates the high-temperature refrigerant, a heat exchanger that finally exchanges heat between the high-temperature side high-temperature refrigerant and the blown air after passing through the evaporator can be adopted.

  Also in the present embodiment, during the second heating mode, the compressor power tends to increase as the temperature of the engine coolant rises due to the engine operation, similarly to the radiator 14 of the second embodiment. Depending on the temperature of the engine cooling water, the heat radiation amount of the water-refrigerant heat exchanger 81 can be increased as compared with the first heating mode.

  Moreover, according to this embodiment, compared with 2nd Embodiment, since the number of the heat exchangers accommodated in the indoor air conditioning unit 10 can be reduced from three to two, the effect that the indoor air conditioning unit 10 can be made compact. Play.

(Other embodiments)
(1) In each of the above-described embodiments, either the first heating mode or the second heating mode is determined in step S9 in FIG. 6 based on the outside air temperature Tam, but other physical quantities other than the outside air temperature Tam. Based on the above, either the first heating mode or the second heating mode may be determined.

  This physical quantity is a physical quantity having a correlation with the heating capacity in the first heating mode, and examples thereof include the suction side refrigerant pressure Ps of the compressor 21, the discharge side refrigerant temperature Ts of the compressor 21, and the refrigerant flow rate. . Compared to the case where the outside air temperature is higher than that at the extremely low temperature, the suction-side refrigerant pressure Ps is lower, the refrigerant flow rate is smaller, and the discharge-side refrigerant temperature Ts when the outside air temperature is low. Becomes higher.

  The threshold of the physical quantity is set based on the physical quantity when the heating capacity in the first heating mode is reduced. Then, the detected physical quantity is compared with a threshold value, and when the detected physical quantity reaches a value indicating a decrease in the heating capacity in the first heating mode, sufficient heating capacity in the first heating mode is obtained. It determines with it not being possible, and determines to 2nd heating mode.

  For example, the suction pressure sensor 48 detects the suction side refrigerant pressure Ps in the first heating mode. Note that the refrigerant pressure may be estimated from the suction temperature detected by the suction temperature sensor 47. When the detected suction side refrigerant pressure Ps is lower than the first predetermined pressure P1, the refrigerant circuit is switched to the second heating mode, and the suction side refrigerant pressure Ps in the second heating mode is higher than the second predetermined pressure (P1 + α). May be higher, the refrigerant circuit may be switched to the first heating mode. The second predetermined pressure is generated immediately after the refrigerant circuit is switched from the first heating mode to the second heating mode, and when the low-pressure side refrigerant pressure is increased by the second heating mode than in the first heating mode. Set to not switch to mode.

  Incidentally, when switching to the second heating mode is determined based on the suction side refrigerant pressure Ps in the first heating mode, frost formation occurs in the outdoor heat exchanger 22 as well as at a very low outdoor temperature. Even when the heating capacity of the first heating mode is reduced, the switching to the second heating mode is possible.

  For example, the discharge temperature sensor 44 detects the discharge-side refrigerant temperature Td in the first heating mode. When the detected discharge-side refrigerant temperature Td is higher than the first predetermined temperature, the refrigerant circuit is switched to the second heating mode, and when the discharge-side refrigerant temperature Td in the second heating mode is lower than the second predetermined temperature, The refrigerant circuit may be switched to the first heating mode. The first predetermined temperature is set in consideration of the temperature range in which the power save control works, and is set to 150 ° C., for example.

  In addition, the refrigerant flow rate may be detected from a flow rate sensor provided in the compressor 21, and the refrigerant circuit may be switched to the second heating mode when the detected refrigerant flow rate is lower than a predetermined flow rate.

  (2) In each of the above-described embodiments, the refrigerant discharged from the compressor 21 flows in the order of the radiator 14, the outdoor heat exchanger 22, and the evaporator 13 in the cooling mode of FIG. 1 and the dehumidifying heating mode of FIG. The refrigerant circuit is configured, that is, the three heat exchangers are arranged in series with respect to the refrigerant flow, but the three heat exchangers are arranged in series with respect to the refrigerant flow. It is not necessary.

  For example, in the cooling mode shown in FIG. 1, a bypass flow path is provided in which the refrigerant flows around the radiator 14, and the refrigerant discharged from the compressor 21 flows into the outdoor heat exchanger 22 around the radiator 14. It is good also as a structure made to do.

  For example, with respect to the dehumidifying and heating mode shown in FIG. It is good also as a structure made to flow in the evaporator 13. FIG. Moreover, it is good also as a structure which flows the refrigerant | coolant after the radiator 14 outflow in parallel with respect to the outdoor heat exchanger 22 and the evaporator 13 at the time of dehumidification heating mode.

  (3) Of the above-described embodiments, in the embodiment using the hot water heater core 61, the engine cooling water is used as the liquid, but other liquids may be used. For example, a coolant for a heating element other than the engine may be used, or a liquid heated by liquid heating means such as an electric heater may be used for the purpose of heating air without the purpose of cooling the heating element.

  (4) In 2nd Embodiment, although the hot water type heater core 61 was used as a means to raise the inlet air temperature of the heat radiator 14, if the blowing air is heated by a heat source different from the refrigeration cycle, Other air heating means may be used, for example, an electric heater or the like may be used.

  (5) In addition, you may combine each above-mentioned embodiment in the range which can be implemented.

DESCRIPTION OF SYMBOLS 1 Vehicle air conditioner 10 Indoor air conditioning unit 13 Evaporator 14 Radiator 20 Refrigeration cycle 21 Compressor 22 Outdoor heat exchanger 23 Heating throttle, 1st heating throttle (heating decompression means, decompression means)
24 Air conditioning throttle (cooling decompression means)
27 1st solenoid valve (refrigerant circuit switching means)
29 Electric 3-way valve (Refrigerant circuit switching means)
31 Second solenoid valve (refrigerant circuit switching means)
61 Hot water heater core (air heating means, first radiator)
62 Engine (liquid heating means)
71 Second heating restriction (pressure reduction means)
81 Water refrigerant heat exchanger (radiator, second radiator)

Claims (8)

A compressor (21) for compressing and discharging the sucked refrigerant;
An outdoor heat exchanger (22) for exchanging heat between the refrigerant and the outdoor air;
An evaporator (13) that is disposed in the air conditioning case (11) and causes the refrigerant to evaporate by exchanging heat between the low-temperature side low-temperature refrigerant and the blown air blown into the vehicle interior;
A heat radiator (14, 61, 81) for exchanging heat between the high-temperature refrigerant on the high-pressure side and the blown air after passing through the evaporator (13) to dissipate the refrigerant;
A refrigerant circuit switching means (27, 29, 31) for switching to any one of a cooling mode refrigerant circuit, a first heating mode refrigerant circuit, and a second heating mode refrigerant circuit,
In the cooling mode refrigerant circuit, the refrigerant discharged from the compressor (21) is supplied to the outdoor heat exchanger (22), the cooling decompression means (24), the evaporator (13), and the compressor (21). By circulating in order, it constitutes a refrigerant circuit that absorbs heat in the evaporator (13) and dissipates heat in the outdoor heat exchanger (22),
The refrigerant circuit in the first heating mode allows the refrigerant discharged from the compressor (21) to flow into the radiator (14), the heating decompression means (23), and the outdoor heat exchanger (22) in this order, The refrigerant flowing out of the outdoor heat exchanger (22) bypasses the evaporator (13) and is guided to the suction side of the compressor (21), so that the heat is absorbed by the outdoor heat exchanger (22), and the heat dissipation. A refrigerant circuit for radiating heat in the vessel (14),
The refrigerant circuit in the second heating mode causes the refrigerant discharged from the compressor (21) to flow into the radiator (14), and the refrigerant flowing out of the radiator (14) to flow into the outdoor heat exchanger (22). ) And the evaporator (13) are bypassed and guided to the suction side of the compressor (21), thereby constituting a refrigerant circuit for radiating heat by the radiator (14),
The switching means (27, 29, 31) is configured to switch from the first heating mode to the second heating mode when a physical quantity correlated with the heating capacity of the first heating mode reaches a value indicating a decrease side of the heating capacity. A vehicle air conditioner characterized by switching the refrigerant circuit to a heating mode. An air heating means (61) that is disposed on the air flow downstream side of the evaporator (13) in the air conditioning case (11) and heats the blown air by a heat source different from the refrigeration cycle,
The radiator (14) is arranged in the air conditioning case (11) on the downstream side of the air flow with respect to the air heating means (61), and after passing through the high-temperature side high-temperature refrigerant and the air heating means (61). The vehicle air conditioner according to claim 1, wherein heat is exchanged with the blown air to dissipate the refrigerant.   The refrigerant circuit in the second heating mode causes the refrigerant discharged from the compressor (21) to flow into the radiator (14), and the refrigerant discharged from the radiator (14) is decompressed by the decompression means (23). The vehicle air conditioner according to claim 1 or 2, wherein the vehicle air conditioner is a refrigerant circuit that is led to the suction side of the compressor (21) after being operated.   The refrigerant circuit in the second heating mode is a refrigerant circuit that causes the refrigerant discharged from the compressor (21) to be decompressed by the decompression means (71) and then flow into the radiator (14). The vehicle air conditioner according to claim 1 or 2. An outside air temperature detecting means (42) for detecting the outside air temperature (Tam) as the physical quantity,
The switching means (27, 29, 31) switches the refrigerant circuit from the first heating mode to the second heating mode when the outside air temperature (Tam) is lower than a predetermined temperature (T1). The vehicle air conditioner according to any one of claims 1 to 4. A suction pressure detecting means (48) for detecting a refrigerant pressure on the suction side of the compressor (21) as the physical quantity;
5. The switch according to claim 1, wherein the switching unit switches the refrigerant circuit from the first heating mode to the second heating mode when the refrigerant pressure in the first heating mode is lower than a predetermined pressure. The vehicle air conditioner according to claim 1. A discharge temperature detecting means (44) for detecting a refrigerant temperature on the discharge side of the compressor (21) as the physical quantity;
5. The switch according to claim 1, wherein the switching unit switches the refrigerant circuit from the first heating mode to the second heating mode when the refrigerant temperature in the first heating mode is higher than a predetermined temperature. The vehicle air conditioner according to claim 1. The radiator is
In the air conditioning case (11), the liquid heated by the liquid heating means (62) flows inside the evaporator (13) downstream of the air flow, and the heated liquid and the liquid A first radiator (61) for exchanging heat with the blown air after passing through the evaporator (13) to dissipate the liquid;
2. The vehicle air conditioner according to claim 1, wherein the vehicle air conditioner includes a second radiator (81) that causes heat exchange between the high-pressure refrigerant on the high-pressure side and the liquid to dissipate the refrigerant.

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