JPH0986149A - Vehicle air conditioner - Google Patents

Abstract

(57) Abstract: In a vehicle air conditioner having a gas injection cycle, it is possible to improve the efficiency of the refrigeration cycle while exhibiting a large heating capacity when necessary. In a refrigeration cycle 21 as a gas injection cycle, a heating indoor heat exchanger 12 functions as a condenser in a heating operation mode. And
When the heating capacity of the heat exchanger 12 reaches the required heating capacity, the control device C of the refrigeration cycle 21
The opening of the electric expansion valve 26 is controlled so that OP becomes maximum. On the other hand, when the heating capacity of the heat exchanger 12 has not reached the required heating capacity, the opening degree of the electric expansion valve 26 is opened to increase the amount of gas injection into the compressor 22. As a result, the work of the compressor 22 increases, and the amount of heat radiated by the refrigerant in the heat exchanger 12 increases, so that the heating capacity increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner having a gas injection cycle, and is particularly suitable as an air conditioner heat pump system for electric vehicles for cold regions.

[0002]

2. Description of the Related Art An apparatus having a gas injection cycle is disclosed in Japanese Patent Laid-Open No. 114668/1989. This conventional refrigeration cycle is shown in FIG.
As shown in FIG. 3, the compressor 101, the condenser 102, the first electric expansion valve 103, the gas-liquid separator 104, the second electric expansion valve 105, and the evaporator 106 are respectively refrigerant pipes 107.
The gas refrigerant separated in the gas-liquid separator 104 is sequentially connected to the gas injection passage 1
It is configured to be injected into the compressor 101 via 08.

Then, the control unit 109 controls the first electric expansion valve 103 so that the degree of supercooling of the condenser 102 becomes smaller than a predetermined value. As a result, the compressor 10
Maintain the optimum amount of gas injection to 1
As a result, the heating capacity of the condenser 102 can be sufficiently obtained.

[0004]

However, in the case of the above-mentioned prior art, since the first electric expansion valve 103 is controlled so that the degree of supercooling of the condenser 102 is always smaller than the predetermined value, Although the heating capacity of the container 102 can be sufficiently obtained, the efficiency of the refrigeration cycle may deteriorate. On the other hand, if the above-mentioned predetermined value is set with priority given to the efficiency of the refrigeration cycle, the required heating capacity may not be obtained this time, and the heating capacity may be insufficient.

Therefore, in view of the above problems, the present invention provides a vehicle air conditioner having a gas injection cycle, which can improve refrigerating cycle efficiency while exhibiting a large heating capacity when necessary. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, claims 1 to
In the invention described in 6, in the refrigeration cycle (21), a compressor (22), a condenser (12), a first depressurizing means (26) whose throttle amount is electrically adjusted, a gas-liquid separator (25), Second
A so-called gas injection cycle including a pressure reducing means (27), an evaporator (24), and a gas injection passage (22d) is used, and the condenser (12) is further provided in the air passage (2), and a control device (40) is provided. ), The rotation speed of the compressor (22) is controlled so that the heating capacity of the condenser (12) becomes a predetermined capacity, and the supercooling degree of the liquid refrigerant in the condenser (12) is a predetermined supercooling degree. In the vehicular air conditioner in which the throttle amount of the first depressurizing means (26) is controlled so that the heating capacity of the condenser (12) reaches the predetermined capacity by the heating capacity determination means (step 230). It is determined whether or not it has been reached, and when it is determined that it has not reached, the throttle amount control means for insufficient capacity (step 240) controls to open the throttle of the first pressure reducing means (26). As .

According to this, when the heating capacity reaches the predetermined capacity, the rotation speed of the compressor (22) is controlled so that the heating capacity of the condenser (12) becomes the predetermined capacity, and the condenser ( The throttle amount of the first pressure reducing means (26) is controlled so that the subcooling degree of the liquid refrigerant in 12) becomes a predetermined subcooling degree. Therefore, if the predetermined degree of supercooling is set to a degree of supercooling that maximizes the efficiency of the refrigeration cycle (21), the efficiency of the refrigeration cycle (21) can be maximized at all times.

On the other hand, when the heating capacity does not reach the predetermined capacity, the throttle of the first pressure reducing means (26) opens, so that the amount of gas injected into the compressor (22) through the gas injection passage (22d). Will increase. Therefore, the compressor (22) performs compression work by adding the refrigerant amount to be gas-injected to the refrigerant circulation amount sucked from the suction port (22b). As a result, the work of compression is increased, and the heat radiation amount of the refrigerant in the condenser (12) is increased, so that the heating capacity is increased.

As described above, according to the present invention, when the heating capacity reaches the above-mentioned predetermined capacity, the efficiency of the refrigeration cycle (21) can be preferentially controlled, and then, for example, rapid heating of the vehicle interior. When the heating capacity does not reach the above-mentioned predetermined capacity as in the early stage of performing, the heating capacity can be improved, so that the efficiency improvement of the refrigeration cycle (21) and the securing of the heating capacity can both be achieved.

Particularly, in the invention according to claim 4, it is determined whether or not the load of the compressor (22) detected by the compressor load detecting means (48) is equal to or more than a predetermined load (step 2).
50), and when it is determined that the load is equal to or higher than the predetermined load, the compressor high load throttle amount control means (step 26).
0), the first decompression means (26) is controlled to close the aperture.

According to this, the throttle of the first pressure reducing means (26) is opened by the control of the throttle amount control means (step 240) when the capacity is insufficient, and as a result, the compressor (2
When the load of 2) exceeds the above predetermined load, the first
Since the throttle of the pressure reducing means (26) is closed and the load increase of the compressor (22) is suppressed, it is possible to prevent the compressor (22) from being overloaded.

Further, in the invention according to claim 5, it is determined whether or not the temperature of the compressor (22) detected by the compressor temperature detecting means (46) is equal to or higher than a predetermined temperature (step 2).
70), and when it is determined that the temperature is equal to or higher than the predetermined temperature, the compressor high temperature throttle amount control means (step 280)
Is characterized by controlling to open the diaphragm of the first pressure reducing means (26).

According to this, when the temperature of the compressor (22) exceeds the predetermined temperature, the first pressure reducing means (2
By opening the throttle of 6), the gas injection amount increases and the temperature rise of the compressor (22) is suppressed, so that the compressor (22) can be prevented from reaching a predetermined temperature or higher.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to an air conditioner for an electric vehicle will be described below with reference to FIGS. First, FIG. 1 shows the overall configuration of this embodiment.
This will be described with reference to FIG. The air conditioning unit 1 is installed in the passenger compartment of an electric vehicle, and its air conditioning duct 2 constitutes an air passage for guiding conditioned air into the passenger compartment. Intake ports 3, 4 for inhaling inside and outside air to one end side of the air conditioning duct 2,
5 are provided. The inside air intake port 4 and the outside air intake port 5 are selectively opened / closed by an inside / outside air switching door 6, and the inside / outside air switching door 6 is driven by a servo motor (not shown).

Further, in the air conditioning duct 2, the suction port 3 is provided.
Blowers 7 for generating an air flow are installed in the air conditioning duct 2 adjacent to the air conditioners 5 to 5. The blower 7 includes a fan motor 7a and centrifugal fans 7b and 7b driven by the fan motor 7a. On the other hand, at the other end of the air conditioning duct 2, a foot outlet 8 that blows conditioned air toward the feet of the passenger in the passenger compartment, a face outlet 9 that blows conditioned air toward the upper half of the passenger in the passenger compartment, and the vehicle front. A defroster outlet 10 that blows conditioned air toward the inner surface of the glass is formed.

An indoor heat exchanger 11 for cooling is provided in the air conditioning duct 2 on the air downstream side of the blower 7. The indoor heat exchanger 11 for cooling is a heat exchanger that constitutes a part of a refrigeration cycle 21 described later, and in the cooling operation mode and the dehumidification operation mode described later, by the heat absorbing action of the refrigerant flowing inside, the air conditioning duct. It functions as an evaporator that dehumidifies and cools the air inside 2. In the heating operation mode described later, this cooling indoor heat exchanger 1
Refrigerant does not flow into 1.

An indoor heat exchanger 12 for heating is provided in the air conditioning duct 2 on the air downstream side of the indoor heat exchanger 11 for cooling. This heating indoor heat exchanger 12
Is a heat exchanger that constitutes a part of a refrigeration cycle 21 described later, and in a heating operation mode and a dehumidification operation mode, which will be described later, is a condensing device that heats the air in the air conditioning duct 2 by the heat radiation effect of the refrigerant flowing inside. Function as a container. In the cooling operation mode, which will be described later, no refrigerant flows in the heating indoor heat exchanger 12.

The air flow path in the air conditioning duct 2 is divided by the partition wall 13 into the first air flow path 14 on the foot outlet 8 side.
And the second air passage 15 on the side of the face outlet 9 and the defroster outlet 10 side. As described above, the reason why the air flow passage in the air conditioning duct 2 is divided into the first air flow passage 14 and the second air flow passage 15 is that the first air flow passage 1 is formed in winter.
Intake of high temperature air from the inside air intake port 3 into the inside of 4 and blowing out warm air to the feet reduces the heating load, and at the same time, sucks outside air of low humidity from the outside air intake port 5 into the second air flow path 15. This is for surely preventing the windshield from fogging.

The door 16 opens and closes the second air flow passage 15, and the door 17 has the first and second air flow passages 14 and 15.
Doors 18 to 20 are used to open and close the partition between
Is a door that opens and closes the air passages of the outlets 8, 9, and 10. The doors 16 to 20 are driven by servo motors (not shown) connected to the doors 16 to 20, respectively. By the way, the refrigeration cycle 21 is used for the indoor heat exchanger 1 for cooling.
This is a heat pump type refrigeration cycle for cooling and heating the inside of a vehicle by means of 1 and an indoor heat exchanger 12 for heating, and is provided with the following equipment in addition to the both indoor heat exchangers 11 and 12.

That is, a compressor 22 that sucks, compresses, and discharges the refrigerant, an electromagnetic four-way valve 23 that switches the flow of the refrigerant,
The outdoor heat exchanger 24, the gas-liquid separator 25 that separates the refrigerant into gas and liquid, and that collects the liquid refrigerant, and the electric expansion valve that reduces the high-pressure side refrigerant of the refrigeration cycle 21 to an intermediate pressure (for example, about 4 to 15 kg / cm ² ). 26, a temperature-operated expansion valve 27 for reducing the pressure of the liquid refrigerant from the gas-liquid separator 25 to a low pressure, a solenoid valve 28a,
28b and check valves 29a to 29e are further provided in the refrigeration cycle 21.

The compressor 22 is an electric compressor, and sucks, compresses, and discharges the refrigerant when driven by an electric motor (not shown). This electric motor is arranged in the hermetically sealed case integrally with the compressor 22, and the rotation speed thereof is continuously varied by being controlled by the inverter 30. This inverter 30 has a vehicle-mounted battery 3
1 is connected, and energization is controlled by the control device 40 (FIG. 2).

A discharge port 22a for discharging the compressed refrigerant, a suction port 22b for sucking the refrigerant on the low pressure side of the cycle, and an intermediate pressure gas refrigerant separated by the gas-liquid separator 25 are injected into the compressor 22. A gas injection port 22c is provided. The gas injection port 22c communicates with the gas refrigerant outlet 25a above the gas-liquid separator 25 via the gas injection passage 22d having the check valve 29e.

A temperature sensing cylinder 27a of a temperature-operated expansion valve 27 is installed in the refrigerant suction passage 22e connected to the suction port 22b, and the opening degree (throttle amount) of the expansion valve 27 is set in the suction passage 22e. The degree of superheat of the refrigerant is adjusted to a predetermined value. Further, the outdoor heat exchanger 24 is installed outside the vehicle compartment, and the electric outdoor fan 24a is installed in the control device 40.
When the energization is controlled by (Fig. 2), the outdoor fan 2
It is designed to exchange heat with the outside air blown from 4a.

Further, the opening degree (throttle amount) of the electric expansion valve 26 is adjusted by controlling energization by the control device 40 (FIG. 2). By the way, as shown in FIG. 2, the control device 40 includes an outside air temperature sensor 41 for detecting the outside air temperature, an intake temperature sensor 42 for detecting the intake side air temperature of the indoor heat exchanger 11 for cooling, and an indoor heat for cooling. An after-evaporator temperature sensor 43 for detecting the air temperature immediately after passing through the exchanger 11, an indoor heat exchanger outlet temperature sensor 44 for detecting the refrigerant temperature immediately after leaving the indoor heating heat exchanger 12,
Also, each detection value from the outdoor heat exchanger outlet temperature sensor 45 for detecting the refrigerant temperature immediately after leaving the outdoor heat exchanger 24 is input.

Further, the control device 40 includes a compressor 22.
Discharged refrigerant temperature sensor 4 for detecting the temperature of the discharged refrigerant
6, a high-pressure sensor 47 for detecting the inlet refrigerant pressure of the electric expansion valve 26, the respective detection values from the line current sensor 48 for detecting the line current of the inverter 30, and a control panel provided on the front surface of the vehicle compartment. 50 levers,
The signal from the switch is input.

As shown in FIG. 3, the control panel 50 includes the following members 5 which are manually operated by an occupant.
1 to 55 are provided. Here, 51 is a temperature setting lever for setting a target value of the temperature of air blown into the vehicle compartment, 5
2 is an air volume switching lever for switching the volume of air blown by the blower 7, 53 is an air conditioner switch for intermittently operating the compressor 22, 54 is a blowing mode switching lever for switching the setting of the blowing mode, and 55 is an inside / outside air switching mode. It is an inside / outside air switching lever for switching between.

Of these, the temperature setting lever 51 is a lever for setting the target value of the temperature of the air blown into the vehicle compartment, and the control device 40 controls the cooling operation mode described later according to the setting position of the lever 51. At times, the target value of the air cooling degree in the indoor heat exchanger 11 for cooling (specifically, the air temperature immediately after passing through this heat exchanger 11) is determined as shown in FIG. At the time and in the heating operation mode, the target value of the air heating degree in the indoor heating heat exchanger 12 (specifically, the refrigerant pressure discharged from the compressor 22) is determined as shown in FIGS.

The temperature setting lever 51 also functions as a lever for determining the operation mode of the refrigeration cycle 21, and the control device 40 controls the lever 5 as shown in FIG.
The operation mode of the refrigeration cycle 21 is switched according to the set position of 1. That is, the control device 40 controls the refrigeration cycle 2 as the lever 51 moves from the left end to the right end in FIG.
The four-way valve 23 and the solenoid valve 28 so that the operation mode 1 is the cooling operation mode, the dehumidification operation mode, and the heating operation mode.
a and 28b are controlled.

A well-known microcomputer including a CPU, a ROM, a RAM and the like (not shown) is provided inside the control device 40, and each of the sensors 41 to 48 is provided.
Each signal from the control panel 50 is input to the microcomputer via an input circuit (not shown) in the control device 40. Then, the microcomputer executes a predetermined process described later, and based on the result, the fan motor 7a, the electromagnetic four-way valve 23, the electric outdoor fans 24a and 24a, the electric expansion valve 26, the electromagnetic valve 28.
a, 28b and the inverter 30 are controlled. In addition,
The control device 40 is supplied with power from the battery 31 when a key switch (not shown) of the automobile is turned on.

By the way, when the air conditioner switch 53 is turned on, the signal is input to the control device 40, and the compressor 2
2 is activated. And the temperature control lever 51
When the cooling operation mode is set by, the refrigerant flows in the path indicated by arrow C in FIG. That is, the high-temperature high-pressure refrigerant discharged from the compressor 22 passes through the four-way valve 23 and the check valve 29b and flows into the outdoor heat exchanger 24, where the outdoor fan 2
The gas refrigerant condenses by exchanging heat with the outside air blown by 4a. Next, since the electromagnetic valve 28a is closed, the refrigerant flowing out of the outdoor heat exchanger 24 passes through the check valve 29d,
The pressure is reduced by the electric expansion valve 26, and a gas-liquid two-phase state of intermediate pressure is obtained.

This intermediate-pressure gas-liquid two-phase refrigerant is used in the gas-liquid separator 2
5, where the refrigerant is separated into a saturated gas refrigerant and a saturated liquid refrigerant. The gas refrigerant flows from the gas refrigerant outlet 25a at the top of the gas-liquid separator 25 to the gas injection passage 22d,
Gas injection port 2 through check valve 29e
2c, an intermediate-pressure gas refrigerant is injected from the port 22c into a part of the compressor 22 during the compression process.

On the other hand, the liquid refrigerant inside the gas-liquid separator 25 is a liquid refrigerant outlet 25b which opens near the bottom of the gas-liquid separator 25.
It further flows out, is decompressed by the temperature-operated expansion valve 27, passes through the electromagnetic valve 28b, and then flows into the indoor heat exchanger 11 for cooling. The refrigerant in the heat exchanger 11 is blown by the blower 7
It absorbs heat from the blast air and evaporates. The cold air that has been absorbed by the heat exchanger 11 and cooled is normally the face air outlet 9
Is blown out into the vehicle interior, and thereby the vehicle interior is cooled.

The gas refrigerant evaporated in the indoor heat exchanger 11 for cooling is sucked into the suction port 22b of the compressor 22 through the refrigerant suction passage 22e. At this time, the temperature of the compressor suction refrigerant is sensed by the temperature-sensitive cylinder 27a installed in the refrigerant suction passage 22e, and transmitted to the expansion valve 27.
Adjusts the flow rate of the refrigerant flowing into the heat exchange 11 so that the compressor suction refrigerant has a predetermined degree of superheat.

Next, when the dehumidifying operation mode is set by the temperature control lever 51, the refrigerant flows in the direction of arrow D in FIG.
It flows in the route shown in. That is, the gas refrigerant discharged from the compressor 22 flows into the indoor heating heat exchanger 12 through the four-way valve 23, where it exchanges heat with the air blown by the blower 7 to condense the gas refrigerant. Then, the refrigerant flowing out of the heat exchanger 12 passes through the check valve 29c and is decompressed by the electric expansion valve 26 to be in a gas-liquid two-phase state of intermediate pressure.

This intermediate-pressure gas-liquid two-phase refrigerant is used in the gas-liquid separator 2
The gas refrigerant that has flowed into the inside 5 and is separated here is sucked into the gas injection port 22c from the gas refrigerant outlet 25a above the gas-liquid separator 25, through the gas injection passage 22d and the check valve 29e. On the other hand, gas-liquid separator 2
The liquid refrigerant in 5 flows out from the liquid refrigerant outlet 25b, is decompressed by the temperature-operated expansion valve 27, and is then opened.
It flows through 8b into the indoor heat exchanger 11 for cooling. Then, the refrigerant in the heat exchanger 11 absorbs heat from the blown air of the blower 7 and evaporates. At this time, since the electromagnetic valve 28a is closed, the refrigerant exiting the heat exchanger 11 does not flow to the outdoor heat exchanger 24 side but is sucked into the compressor 22.

As described above, in the dehumidifying operation mode, the indoor heat exchanger 1 for cooling installed in the indoor air conditioning unit 1
Since the refrigerant flows through both 1 and the indoor heat exchanger 12 for heating, the air blown from the blower 7 is first cooled and dehumidified by the indoor heat exchanger 11 for cooling, and then by the indoor heat exchanger 12 for heating. Reheated. Here, since the refrigerant heat radiation amount in the heating indoor heat exchanger 12 is the heat absorption amount in the cooling indoor heat exchanger 11 plus the work amount in the compressor 22,
The temperature of the air blown into the vehicle compartment is higher than the temperature of the air taken in through the intake ports 3, 4, 5. Therefore, while dehumidifying,
It becomes possible to perform heating.

Next, when the heating operation mode is set by the temperature control lever 51, the refrigerant flows in the direction of arrow H in FIG.
It flows in the route shown in. That is, the gas refrigerant discharged from the compressor 22 flows into the indoor heating heat exchanger 12 through the four-way valve 23, where it exchanges heat with the air blown by the blower 7 to condense the gas refrigerant. The warm air heated by the heat dissipation of the gas refrigerant is blown out mainly from the foot outlet 8 into the vehicle compartment, thereby heating the vehicle interior.

The refrigerant discharged from the indoor heat exchanger 12 for heating passes through the check valve 29c and is decompressed by the electric expansion valve 26 to be in a gas-liquid two-phase state of intermediate pressure. The gas-liquid two-phase refrigerant of this intermediate pressure flows into the gas-liquid separator 25, and the gas refrigerant separated here is the gas refrigerant outlet 25 a at the upper part of the gas-liquid separator 25.
Through the gas injection passage 22d and the check valve 29e to be sucked into the gas injection port 22c.

On the other hand, the liquid refrigerant in the gas-liquid separator 25 flows out from the liquid refrigerant outlet 25b, is decompressed by the temperature operated expansion valve 27, passes through the check valve 29a, and then the outdoor heat exchanger 24.
Flows into. Then, the refrigerant in the outdoor heat exchanger 24 absorbs heat from the blown air (outside air) of the outdoor fan 24a and evaporates. The gas refrigerant evaporated in the outdoor heat exchanger 24 passes through the electromagnetic valve 28a and is discharged from the refrigerant suction passage 22e to the compressor 2
2 is sucked into the suction port 22b.

Next, the control processing of the electric expansion valve 26 and the inverter 30 by the microcomputer of the control device 40 will be described with reference to the flowchart of FIG. When the key switch is turned on and power is supplied to the control device 40, the routine of FIG. 8 is started. Then, first, at step 100, each of the sensors 41 to 4 is
8 and each signal from the control panel 50 are read. Then, in the next step 110, the operation mode of the refrigeration cycle 21 is determined as shown in FIG. 7 according to the setting position of the temperature setting lever 51.

Then, in the next step 120, it is determined which mode the operation mode determined in step 110 is. When it is determined that the cooling operation mode is set, steps 130 to 170 are performed,
If it is determined to be in the heating operation mode, step 18
The processes of 0 to 280 are performed, and when it is determined that the dehumidifying operation mode is set, the processes of steps 290 to 330 are performed.

First, the case where it is determined in step 120 that the operation mode is the cooling operation mode will be described. Step 1
At 30, the target outlet temperature TEO corresponding to the set position of the temperature setting lever 51 is determined by searching the map shown in FIG. 4 stored in the ROM. Then, in the next step 140, the inverter 30 is controlled so that the temperature detected by the post-evaporator temperature sensor 43 (air temperature immediately after passing through the indoor heat exchanger 11 for cooling) becomes the TEO.

Then, in the next step 150, the degree of supercooling (SC) of the condensed liquid refrigerant in the outdoor heat exchanger 24 is
It is calculated based on the following formula 1.

[0044]

## EQU1 ## SC = T (Ph) -Tos where Tos is a value detected by the outdoor heat exchanger outlet temperature sensor 45. Further, T (Ph) is the refrigerant condensing temperature calculated from the detection value of the high pressure sensor 47. That is, since the detected value of the high-pressure sensor 47 corresponds to the refrigerant condensing pressure, in the present embodiment, a map (not shown) showing the correlation between the refrigerant condensing pressure and the refrigerant condensing temperature is stored in the ROM and the high-pressure sensor 47 is stored. The condensation temperature corresponding to the detected value is calculated by searching from this map.

Then, in the next step 160, the target degree of supercooling (SCO) corresponding to the outside air temperature detected by the outside air temperature sensor 41 is calculated by searching the map of FIG. 9 stored in the ROM. By calculating the target supercooling degree SCO from the map of FIG. 9, the outdoor heat exchanger 2
It is possible to maximize the cooling COP of the refrigeration cycle 21 (= the above-mentioned heat radiation capacity Q / power W of the compressor 22) while optimizing the heat radiation capacity Q in No. 4.

That is, in general, in summer when the outside air temperature is high, the compressor 22 is operated to cool the inside of the vehicle as the outside air temperature rises to secure the cooling capacity. Therefore, at this time, the high pressure increases and the refrigerant temperature of the outdoor heat exchanger 24 also increases, resulting in a large temperature difference between the refrigerant temperature and the outside air temperature. That is, the outdoor heat exchanger 2
The heat radiation capacity Q in 4 becomes large.

Therefore, the target supercooling degree SCO is calculated as a large value, and as a result, even if the power W of the compressor 22 becomes large, the capacity Q becomes larger and the cooling COP becomes larger.
, The target supercooling degree SCO is calculated as a large value when the outside air temperature is high. Then, in the next step 170, the opening degree of the electric expansion valve 26 is controlled so that the subcooling degree SC calculated in step 150 becomes the target subcooling degree SCO calculated in step 160. Specifically, first, the deviation (ΔSC) between the SC and SCO is calculated, and then the increase / decrease opening ΔEVC of the electric expansion valve 26 corresponding to this deviation ΔSC is calculated from a map (not shown) stored in the ROM. To do. Then, the current opening degree of the electric expansion valve 26 is increased / decreased by the increase / decrease opening degree ΔEVC.

Next, the case where it is determined in step 120 that the operation mode is the dehumidifying operation mode will be described. In step 290, the target high pressure PCO corresponding to the set position of the temperature setting lever 51 is determined by searching the map shown in FIG. 5 stored in the ROM. And
In the next step 300, the inverter 30 is controlled so that the high pressure detected by the high pressure sensor 47 becomes the PCO.

Then, in the next step 310, the degree of subcooling SC of the condensed liquid refrigerant in the heating indoor heat exchanger 12
Is calculated based on the following mathematical formula 2.

[0050]

## EQU2 ## SC = T (Ph) -Tcs Here, Tcs is a detection value of the indoor heat exchanger outlet temperature sensor 44. Then, in the next step 320, the target degree of supercooling SCO corresponding to the post-evaporator temperature detected by the post-evaporator temperature sensor 43 is calculated by searching the map of FIG. 10 stored in the ROM. By calculating the target degree of supercooling SCO from the map of FIG. 10, while optimizing the heat radiation capacity Q in the indoor heat exchanger for heating 12,
It is possible to maximize the dehumidification COP of the refrigeration cycle 21 (= the heat radiation capacity Q / the power W of the compressor 22).

That is, the post-evaporator temperature detected by the post-evaporator temperature sensor 43 corresponds to the temperature of the air passing through the indoor heating heat exchanger 12. Therefore, the low temperature after the evaporator means that the temperature difference between the refrigerant temperature in the indoor heating heat exchanger 12 and the temperature of the air passing through the heat exchanger 12 is large. That is, the heat dissipation capability Q is large.

Therefore, the target degree of supercooling SCO is calculated as a large value, and as a result, even if the power W of the compressor 22 is increased, the capacity Q is further increased and the dehumidification COP is increased.
Therefore, when the post-evaporator temperature is low, the target supercooling degree SCO is calculated as a large value. Then, in the next step 330, the subcooling degree SC calculated in step 310 is the target subcooling degree SC calculated in step 320.
The opening degree of the electric expansion valve 26 is controlled so that it becomes O.
The specific control method of this step 330 is step 17
Since it is the same as 0, the description thereof is omitted.

Next, the case where it is determined in step 120 that the heating operation mode is set will be described. In step 180, the target high pressure PCO corresponding to the set position of the temperature setting lever 51 is determined by searching the map shown in FIG. 6 stored in the ROM. And
In the next step 190, the inverter 30 is controlled so that the high pressure detected by the high pressure sensor 47 becomes the PCO.

Then, in the next step 200, the degree of supercooling SC of the condensed liquid refrigerant in the heating indoor heat exchanger 12
Is calculated based on Equation 2 above. Then, in the next step 210, the target degree of supercooling SCO corresponding to the suction temperature detected by the suction temperature sensor 42 is calculated by searching the map of FIG. 11 stored in the ROM. By calculating the target subcooling degree SCO from the map of FIG. 11, the heating COP of the refrigeration cycle 21 is optimized while optimizing the heat radiation capacity Q of the indoor heating heat exchanger 12.
(= The heat radiation capacity Q / the power W of the compressor 22) can be maximized.

That is, in the heating operation mode, since the refrigerant does not flow into the cooling indoor heat exchanger 11, the suction temperature (cooling indoor heat exchanger 11 detected by the suction temperature sensor 42 is detected.
Suction side air temperature) corresponds to the temperature of the air passing through the indoor heating heat exchanger 12. Therefore, the low suction temperature means that the temperature difference between the refrigerant temperature in the indoor heating heat exchanger 12 and the temperature of the air passing through the heat exchanger 12 is large. That is, the heat dissipation capability Q is large.

Therefore, the target supercooling degree SCO is calculated as a large value, and as a result, even if the power W of the compressor 22 becomes large, the capacity Q becomes larger and the heating COP becomes larger.
Therefore, when the post-evaporator temperature is low, the target supercooling degree SCO is calculated as a large value. Then, in the next step 220, the subcooling degree SC calculated in step 200 is the target subcooling degree SC calculated in step 210.
The opening degree of the electric expansion valve 26 is controlled so that it becomes O.
The specific control method of this step 220 is step 17
Since it is the same as 0, the description thereof is omitted.

By the control in steps 180 to 220, the heating capacity is basically controlled by the compressor rotation speed,
The opening degree of the electric expansion valve 26 is controlled so that the efficiency (COP) of the refrigeration cycle 21 is maximized. However, for example, in the early stage of rapid heating of the passenger compartment, when the compressor rotation speed is the maximum rotation speed but the high-pressure pressure does not reach the target high-pressure pressure PCO and the heating capacity is insufficient, the efficiency of the refrigeration cycle 21 is somewhat increased. Even if it is dropped, improving heating capacity must be prioritized.

Therefore, in this embodiment, the following step 2
At 30, the high pressure detected by the high pressure sensor 47 is the target high pressure P while the compressor rotation speed is the highest.
It is determined whether or not CO is reached. Here, YES
If it is determined that the heating capacity is insufficient, step 2
At 40, the electric expansion valve 26 is opened by a predetermined amount. The compressor rotation speed can be detected based on the inverter frequency input to the control device 40.

According to this, for example, if the electric expansion valve 26 is opened by a predetermined amount by the process of step 240 while the refrigeration cycle 21 is stable in the state shown by the solid line in FIG. The state becomes stable in the state shown by the alternate long and short dash line in FIG. Therefore, the compressor 22
Since the amount of gas injection into the compressor increases, the compressor 22
In addition, the refrigerant circulation amount sucked from the suction port 22b is added with the refrigerant amount injected by the gas injection to perform compression work. As a result, although the work of the compressor 22 increases and the efficiency of the refrigeration cycle 21 decreases, the amount of refrigerant radiation in the indoor heating heat exchanger 12 increases, so
Heating capacity is improved. As a result, the insufficient heating capacity is resolved.

Further, when the electric expansion valve 26 is opened by the process of step 240, the gas injection amount increases, and the work amount (load) of the compressor 22 increases as described above. The load of 30 increases. Therefore, in the next step 250, by checking whether the line current of the inverter 30 detected by the line current sensor 48 is a predetermined current or more, the inverter 30
Is overloaded. Then, if YES is determined, in the next step 260, the electric expansion valve 26 is closed by a predetermined amount. This reduces the amount of gas injection into the compressor 22, so that the inverter 30 can be prevented from being overloaded.

Further, in the next step 270, it is judged whether or not the compressor 22 is heated above the allowable temperature by checking whether or not the discharge refrigerant temperature detected by the discharge refrigerant temperature sensor 46 is equal to or higher than a predetermined temperature. To do. If YES is determined, in step 280, the electric expansion valve 26 is opened by a predetermined amount. As a result, the amount of gas injection increases and the discharge temperature decreases.

As described above, in the present embodiment, when the heating capacity is sufficient in the heating operation mode, the opening degree of the electric expansion valve 26 is controlled so that the efficiency of the refrigeration cycle 21 is maximized. When the heating capacity is insufficient as in the early stage of rapid heating, the opening degree of the electric expansion valve 26 is increased to increase the gas injection amount and improve the heating capacity.
It is possible to achieve both improvement of efficiency and securing of heating capacity.

(Other Embodiments) In the above embodiment, the shortage of heating capacity is determined based on the high pressure.
The determination may be made based on the air temperature immediately after passing through the indoor heating heat exchanger 12. In short, the determination may be made based on the physical quantity related to the heating capacity of the indoor heating heat exchanger 12.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a control system of the above embodiment.

FIG. 3 is a front view of a control panel 50 of the above embodiment.

FIG. 4 is a map showing a relationship between a set position of a temperature setting lever 51 of FIG. 3 and a target outlet temperature in a cooling operation mode.

FIG. 5 is a map showing the relationship between the target high pressure and the set position of the temperature setting lever 51 in the dehumidifying operation mode.

FIG. 6 is a map showing the relationship between the target high pressure and the set position of the temperature setting lever 51 in the heating operation mode.

FIG. 7 is a diagram showing a relationship of a refrigeration cycle operation mode with respect to an entire operating region of the temperature setting lever 51.

FIG. 8 is a control flowchart of the microcomputer of the above embodiment.

FIG. 9 is an outside air temperature and a target supercooling degree SCO of the above embodiment.
It is a map showing the relationship with.

FIG. 10 is a map showing the relationship between the evaporator post-temperature and the target degree of supercooling SCO in the above embodiment.

FIG. 11: Suction temperature and target supercooling degree SC of the above embodiment
It is a map showing the relationship with O.

FIG. 12 is a Mollier diagram of the refrigeration cycle 21 of the above embodiment.

FIG. 13 is an overall configuration diagram of a device having a conventional gas injection.

[Explanation of symbols]

2 ... Air conditioning duct (air passage), 7 ... Blower, 11 ... Cooling indoor heat exchanger, 12 ... Heating indoor heat exchanger (condenser), 21 ... Refrigeration cycle, 22 ... Compressor, 22a ... Discharge port, 22b ... Intake port, 22c ... Gas injection port, 22d ... Gas injection passageway, 23 ... Four-way valve, 24 ... Outdoor heat exchanger, 25 ... Gas-liquid separator, 26 ... Electric expansion valve (first pressure reducing means), 27 ... Temperature-operated expansion valve (second pressure reducing means), 40 ... Control device, 4
6 ... Discharge refrigerant temperature sensor (compressor temperature detecting means), 48
... Line current sensor (compressor load detection means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Inagaki 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (72) Inventor Yukatsu Ozaki, 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Stock Company, Japan Automotive Parts Research Institute

Claims (6)

[Claims] 1. A blower (7) for generating an air flow, an air passage (2) for guiding the air generated by the blower (7) into a passenger compartment, and a low-pressure refrigerant of a refrigeration cycle (21) by itself. A suction port (22b), a gas injection port (22c) for introducing a medium-pressure gas refrigerant of the refrigeration cycle (21), and a discharge port (22a) for discharging the high-pressure refrigerant compressed by itself. A compressor (22) having the same, a condenser (12) provided in the air passage (2) and condensing high-pressure refrigerant from the discharge port (22a) of the compressor (22); A first pressure reducing means (26) configured to reduce the pressure of the high-pressure refrigerant from (12) to an intermediate pressure and electrically adjust the throttle amount, and an intermediate pressure from the first pressure reducing means (26). cold A gas-liquid separator (25) for gas-liquid separation, a second pressure reducing means (27) for reducing the intermediate-pressure liquid refrigerant separated by the gas-liquid separator (25) to a low pressure, and the second pressure reducing means An evaporator (24) for evaporating the low-pressure refrigerant from (27) and the intermediate-pressure gas refrigerant separated by the gas-liquid separator (25) are guided to the gas injection port (22c) of the compressor (22). Gas injection passage (22
d), compressor rotation speed control means (steps 180, 190) for controlling the rotation speed of the compressor (22) so that the heating capacity of the condenser (12) becomes a predetermined capacity, and the condenser ( 12) A control device (40) provided with throttle amount control means (steps 200 to 220) for controlling the throttle amount of the first pressure reducing means (26) so that the supercooling degree of the liquid refrigerant in 12) becomes a predetermined supercooling degree. And a heating capacity determination means (step 230) for determining whether or not the heating capacity of the condenser (12) has reached the predetermined capacity. When the heating capacity determination means (step 230) determines that the heating capacity of the condenser (12) does not reach the predetermined capacity, the first pressure reducing means (2)
6) A vehicular air-conditioning system, characterized in that it comprises a throttle amount control means (step 240) when the capacity is insufficient to control the first pressure reducing means (26) so as to open the throttle. 2. The heating capacity determination means (step 23)
0) is configured to determine whether or not the heating capacity of the condenser (12) has reached the predetermined capacity even when the compressor (22) has the highest rotation speed. The vehicle air conditioner according to claim 1. 3. The vehicle air conditioner according to claim 1, wherein the predetermined degree of supercooling is a degree of supercooling that maximizes the coefficient of performance of the refrigeration cycle (21). 4. A compressor load detecting means (48) for detecting a load of the compressor (22), wherein the control device (40) detects the compressor () detected by the compressor load detecting means (48). Two
The load of the compressor (22) is equal to or more than the predetermined load by the compressor load determining means (step 250) for determining whether the load of 2) is equal to or more than the predetermined load. And a compressor high load throttle amount control means (step 260) for controlling the first pressure reducing means (26) so as to close the throttle of the first pressure reducing means (26) when it is determined that there is. The vehicle air conditioner according to any one of claims 1 to 3, which is characterized. 5. A compressor temperature detecting means (46) for detecting the temperature of the compressor (22) is provided, and the control device (40) is configured to detect the compressor () detected by the compressor temperature detecting means (46). Two
The compressor temperature determining means (step 270) for determining whether the temperature of 2) is equal to or higher than the predetermined temperature, and the compressor temperature determining means (step 270) determines whether the temperature of the compressor (22) is equal to or higher than the predetermined temperature. When it is determined that there is, the compressor high temperature throttle amount control means (step 280) for controlling the first pressure reducing means (26) so as to open the throttle of the first pressure reducing means (26). The vehicle air conditioner according to any one of claims 1 to 4. 6. The vehicle air conditioner according to claim 1, wherein an electric compressor (22) driven by an electric motor is used as the compressor (22). .