JP2003054243A - Vehicular air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably save power of a compressor driving source for a vehicular air conditioner. SOLUTION: During a cooling operation to drive a compressor 41 and to cool air by an evaporator 45, an enthalpy ir of inside air and an enthalpy io of outside air are computed, the sizes of both computed enthalpies ir, io are compared, and switching of an inlet port is automatically controlled so as to bring in the air having a smaller enthalpy between the outside air and the inside air. Thereby, since the air having smaller enthalpy is brought in between the outside air and the inside air, in comparison with the conventional case wherein the air conditioner is indiscriminately put in an outside air mode on condition that TAO is not less than a prescribed temperature, power of a driving source for the compressor 41 can be surely saved.

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 capable of automatically controlling switching between an intake mode and an intake mode.

[0002]

2. Description of the Related Art A vehicular air conditioner equipped with an evaporator for evaporating a refrigerant circulated by a compressor to cool air and capable of automatically controlling switching of an inlet mode between an inside air mode and an outside air mode is conventionally known. Target outlet temperature TAO is first
At the time of cooldown at a predetermined temperature (for example, −12 ° C. when traveling at 40 km / h) or lower, the mode is switched to the inside air mode to achieve immediate effect of the cooldown performance. On the other hand, during the normal cooling operation in which the target outlet temperature TAO is equal to or higher than the second predetermined temperature (for example, −5.5 ° C. when traveling at 40 km / h), the outside air mode is switched to obtain a fresh feeling.

[0003]

However, if the outside air mode is uniformly set during the normal cooling operation, the power saving of the compressor drive source may be impaired. For example, the target outlet temperature T
AO is the normal cooling temperature range (TAO ≧ -5.5 ° C (40 km
/ H))), when the enthalpy ir of the inside air is smaller than the enthalpy io of the outside air, the mode of the inside air saves the power of the compressor drive source.

In view of the above points, it is an object of the present invention to surely save the power of the compressor drive source of the vehicle air conditioner.

[0005]

In order to achieve the above object, in the invention according to claim 1, an air conditioning duct (10) forming an air passage (10a) through which air is blown toward the passenger compartment, The air passage (10a) includes an evaporator (45) arranged in the air passage (10a) for cooling air and a compressor (41) for compressing and discharging the refrigerant passing through the evaporator (45). In an air conditioner for a vehicle capable of automatically controlling switching of an inlet mode between an inside air mode for introducing inside air and an outside air mode for introducing outside air into an air passageway (10a), a compressor (41) is driven to drive an evaporator ( 45), the enthalpy (ir) of the inside air and the enthalpy (io) of the outside air are calculated during the cooling operation for cooling the air,
The calculated two enthalpies (ir, io) are compared in size, and the switching of the suction port mode is automatically controlled so as to introduce the air having the smaller enthalpy from the inside air and the outside air.

As a result, the air with the smaller enthalpy is introduced into the compressor (4
It is possible to surely save the power of the drive source in 1).

Then, as in the invention described in claim 2,
The enthalpy (ir) of the inside air is measured by the inside air temperature sensor (7
Calculated based on the inside air temperature (TR) detected by 1) and the inside air humidity (RHr) detected by the inside air humidity sensor (77) to detect the enthalpy (io) of the outside air by the outside air temperature sensor (72). Outside temperature (TAM)
And the outside air humidity (RHo) detected by the outside air humidity sensor (77).

According to the third aspect of the invention, the inside air / outside air switching box (1) is formed with an inside air inlet (11) and an outside air inlet (12) for the inside air humidity sensor and the outside air humidity sensor.
0b) the same one humidity sensor (7
7), and when one of the suction port modes is switched to, the other mode is periodically switched, and the humidity (RHo, RHr) before and after switching is changed by one humidity sensor (77). By detecting each,
The feature is that both enthalpies (ir, io) are periodically compared in magnitude.

As a result, since the inside air humidity (RHr) and the outside air humidity (RHo) can be detected by one humidity sensor (77), the inside air humidity sensor and the outside air humidity sensor are provided one by one. Compared with this, the number of parts can be reduced and the cost can be reduced.

Further, according to the invention described in claim 4, a characteristic map showing a change in the blown air volume of the air corresponding to a change in the target outlet temperature (TAO) of the air blown into the vehicle compartment is provided, and the characteristic map is The blowout air volume can be automatically controlled based on the above, and the characteristic map in the inside air mode is characterized in that it is offset in a direction in which the blowout air amount becomes smaller than that in the outside air mode.

Regarding the noise generated when air flows through the air passage (10a), the noise level in the inside air mode is generally higher than that in the outside air mode. On the other hand, according to the invention described in claim 4, the amount of air blown out in the inside air mode is smaller than that in the outside air mode, so that the noise level in the inside air mode can be reduced, which is preferable.

By the way, at the time of cool down (for example, when the target outlet temperature is -12 ° C. or less when traveling at 40 km / h)
In some cases, it may be desirable to give priority to degrading the vehicle interior temperature in a short time rather than saving the power of the drive source of the compressor (41). If the invention according to claim 5 is applied to such a case, when the deviation between the set temperature (Tset) set by the occupant and the inside air temperature (TR) is larger than a predetermined value, both This is preferable because the mode is switched to the inside air mode regardless of the magnitude of the enthalpy (ir, io).

Further, in the invention according to claim 6, it is estimated whether or not the window glass (3) of the vehicle is easily fogged, and if it is estimated that the window glass (3) is easily fogged, both enthalpies ( It is characterized by switching to the outside air mode regardless of the magnitude of ir, io).

By the way, in the prior art, since the outside air mode was uniformly set during the normal cooling operation, the fogging of the window glass did not pose a problem, but according to the invention of claim 1, the enthalpy of the inside air and the outside air is small. When the other air is introduced, ir ≦ io in most cases during the normal cooling operation, and the cooling operation is performed in the internal air mode for a long time, so that the window glass may become a problem. If the invention described in claim 6 is applied to such a case, it is possible to save the drive source of the compressor (41) while preventing the fogging of the window glass.

As an example of estimating whether or not the cloudy state is likely to occur, when the compressor (41) is operating, the absolute humidity of the air passing through the evaporator (45) is low,
It is estimated that the window glass is not easily fogged and the compressor (4
When the operation of 1) is stopped, it can be considered that the absolute humidity of the air that has passed through the evaporator (45) is high and the window glass is likely to be fogged.

Incidentally, in Japanese Patent Laid-Open No. 5-345515, the required blowout temperature is determined based on the window glass temperature estimated from the outside air temperature and the inside air temperature, and the required blowout temperature and the target blowout temperature are compared and low. An air conditioner has been proposed in which the operation of the compressor is controlled so as to reach the other temperature, thereby ensuring antifogging and comfort. However, since the air conditioner described in this publication does not introduce the air having the smaller enthalpy from the inside air and the outside air unlike the present invention, it is not possible to save the power of the compressor drive source.

In order to estimate whether or not the window glass (3) of the vehicle is easily fogged, the invention according to claim 7 uses an infrared sensor for detecting the temperature of the window glass (3) of the vehicle. Whether or not the window glass (3) is easily fogged based on the window glass temperature detected by the infrared sensor (78) and the inside air humidity (RHr) detected by the inside air humidity sensor (77). If it is estimated that it is estimated that the cloudy state is likely to occur, it is characterized in that the mode is switched to the outside air mode regardless of the magnitude of both enthalpies (ir, io).

Thus, the enthalpy (ir) of the inside air
An internal air humidity sensor (77) provided for calculating the internal air humidity (RH) detected by the sensor (77) is used.
Since it is possible to estimate whether or not the window glass (3) is easily fogged by using r), it is possible to reduce the cost by reducing the number of parts without requiring a new sensor. it can.

Further, in the invention according to claim 8, comprising a CO ₂ concentration detection means for detecting the concentration of carbon dioxide in the inside air, if the carbon dioxide concentration detected by the CO ₂ concentration detector is larger than a predetermined value Both enthalpies (i
It is characterized by switching to the outside air mode regardless of the magnitude of r, io).

By the way, in the prior art, since the outside air mode was uniformly set during the normal cooling operation, the increase of the carbon dioxide concentration in the passenger compartment did not pose a problem, but according to the invention of claim 1, the inside air and the outside air are When the air with the smaller enthalpy is introduced, ir ≦ io in most cases during the normal cooling operation, and the cooling operation is performed in the internal air mode for a long time, which may cause an increase in carbon dioxide concentration. . If the invention described in claim 8 is applied to such a case, it is possible to save the power of the drive source of the compressor (41) while preventing the increase of the carbon dioxide concentration.

The reference numerals in parentheses for each means described above are examples showing the correspondence with the specific means described in the embodiments described later.

[0022]

1 to 7 show an embodiment of the present invention, FIG. 1 is a schematic diagram showing the overall configuration of a vehicle air conditioner, and FIG. 2 is a vehicle air conditioner. It is a block diagram showing a control system.

The air conditioner of the present embodiment is an air conditioner (actuator) of the air conditioner unit 1 for air conditioning the passenger compartment.
Is controlled by an air-conditioning control device (hereinafter referred to as an air conditioner ECU) 7 to automatically control the temperature inside the vehicle compartment to a preset temperature.

As shown in FIG. 1, the air conditioner unit 1
Is an air passage 10a through which air is blown toward the passenger compartment.
The air-conditioning duct 10 that forms the air-conditioning duct, the centrifugal blower 30 that generates an air flow in the air-conditioning duct 10, the refrigeration cycle 40 that cools the air flowing in the air-conditioning duct 10 to cool the vehicle interior, and the air-conditioning duct 10. It is composed of a cooling water circuit 50 and the like for heating the air flowing through to heat the interior of the vehicle.

The air conditioning duct 10 is arranged on the front side in the vehicle compartment. The most upstream side (windward side) of the air conditioning duct 10 is a portion forming a suction port switching box (inside / outside air switching box) 10b, and an inside air suction port 11 for taking in vehicle interior air (hereinafter referred to as inside air) and an outside air compartment. (Hereinafter referred to as outside air)
It has an outside air suction port 12 for taking in. Further, inside and outside air (suction port) switching dampers 13 are rotatably mounted inside the inside air suction port 11 and the outside air suction port 12. The inside / outside air switching damper 13 is driven by an actuator 14 (see FIG. 2) such as a servo motor to switch the suction mode to the inside air mode or the outside air mode. The inside / outside air switching damper 13 constitutes an inside / outside air switching unit together with the suction port switching box 10b.

Further, the most downstream side (leeward side) of the air conditioning duct 10 is a portion forming a blower outlet switching box, and a defroster opening portion, a face opening portion and a foot opening portion are formed. A defroster duct 15 is connected to the defroster opening, and at the most downstream end of the defroster duct 15, a defroster outlet 18 that mainly blows warm air toward the inner surface of the windshield 3 of the vehicle opens. ing.

A face duct 16 is connected to the face opening, and a face outlet 19 is provided at the most downstream end of the face duct 16 for blowing cold air mainly toward the head and chest of the occupant. . Furthermore, a foot duct 17 is connected to the foot opening, and a foot outlet 20 that mainly blows warm air toward the foot of the occupant is opened at the most downstream end of the foot duct 17.

Two blower outlet switching dampers 21 are rotatably mounted inside each blower outlet. Two
The individual blower outlet switching dampers 21 are driven by an actuator 22 (see FIG. 2) such as a servo motor to switch the blower outlet mode to any one of a face mode, a bilevel mode, a foot mode, a foot differential mode, and a defroster mode. .

By the way, in the face mode, the entire amount of the conditioned air is blown out from the face outlet 19, and in the bilevel mode, the conditioned air is blown into the face outlet 19 and the foot outlet 20.
In the foot mode, most of the conditioned air (about 80% of the total blown air volume) is blown from the foot outlet 20 and a part of the conditioned air is discharged from the defroster outlet 1.
Blow out from 8. Further, in the foot differential mode, the air is blown out from the defroster outlet 18 and the foot outlet 20, and specifically, the amount of air blown out from the defroster outlet 18 is about 40% of the total blown air amount, at least 1% of the total blown air amount.
It is set to / 3 or more. Further, in the defroster mode, the entire amount of conditioned air is blown out from the defroster outlet 18. The two outlet switching dampers 21 constitute an outlet switching means together with the outlet switching box.

The centrifugal blower 30 has a centrifugal fan 31 rotatably housed in a scroll case integrally formed with the air conditioning duct 10, and a blower motor 32 for rotationally driving the centrifugal fan 31. . And
The blower motor 32 is a blower drive circuit 33 (see FIG. 2).
The amount of air blown (the rotation speed of the centrifugal fan 31) is controlled based on the blower terminal voltage (hereinafter referred to as the blower voltage) applied via the.

The refrigerating cycle 40 is driven by the engine 6 by a belt to compress the refrigerant, a condenser 42 for condensing and liquefying the compressed refrigerant, and a condensed and liquefied refrigerant to be separated into gas and liquid, so that only the liquid refrigerant is discharged. It comprises a liquid receiver 43 that flows downstream, an expansion valve 44 that decompresses and expands the liquid refrigerant, an evaporator 45 that evaporates the decompressed and expanded refrigerant, and a refrigerant pipe that connects these in an annular shape.

Of these, the evaporator 45 is arranged in the air-conditioning duct 10 so as to completely block the air passage, and has an air cooling function of cooling the air passing therethrough and an air dehumidification for dehumidifying the air passing therethrough. It is an indoor heat exchanger that operates. In other words, the evaporator 45 is a cooling heat exchanger that cools and dehumidifies the conditioned air by operating the compressor 41.

An electromagnetic clutch 46 is connected to the compressor 41 as clutch means for connecting and disconnecting the rotational power transmission from the engine 6 to the compressor 41. The electromagnetic clutch 46 is controlled by the clutch drive circuit 47 (see FIG. 2) (in the case of the variable displacement compressor 41, the discharge pressure is controlled).

When the electromagnetic clutch 46 is energized, the rotational power of the engine 6 is transmitted to the compressor 41,
An air cooling action is performed by the evaporator 45. At this time,
The discharge capacity of the refrigerant discharged from the discharge port of the compressor 41 is
It changes in proportion to the rotation speed of the engine 6. Further, when the energization of the electromagnetic clutch 46 is stopped, the engine 6 and the compressor 41 are cut off, and the air cooling action by the evaporator 45 is stopped. Here, the condenser 42 is arranged in a place where the traveling wind generated when the vehicle travels is easily received, and the outdoor heat exchange for exchanging heat between the refrigerant flowing inside and the outside air blown by the cooling fan 48 and the traveling wind. It is a vessel.

The cooling water circuit 50 is a circuit for circulating the cooling water warmed by the water jacket of the engine 6 by a water pump (not shown), and has a radiator, a thermostat (neither is shown) and a heater core 51. . This heater core 51 has an engine 6 inside.
The cooling water that has cooled the air flows, and the cooling air is reheated using this cooling water as a heat source for heating.

The heater core 51 is provided in the air conditioning duct 10 so as to partially block the air passage.
It is arranged on the downstream side. An air mix damper 52 is rotatably attached on the air upstream side of the heater core 51. The air mix damper 52 is driven by an actuator 53 (see FIG. 2) such as a servo motor, and adjusts the ratio between the amount of air passing through the heater core 51 and the amount of air bypassing the heater core 51 depending on the stop position. , Serves as an outlet temperature adjusting means for adjusting the outlet temperature of the air blown into the vehicle compartment.

Next, the configuration of the control system of this embodiment will be described with reference to FIGS. 1, 2 and 3. Air conditioner EC
A switch signal from each switch on the control panel P provided on the front surface of the vehicle compartment and a sensor signal from each sensor are input to U2. And the air conditioner EC
U2 controls the operation of the air conditioner based on these signals.

Here, each switch on the control panel P is, as shown in FIG. 3, an air conditioner (A / C) switch 60 for instructing the operation and stop of the air conditioner.
Also, an economy (ECO) switch 61, a suction port switching switch 62 for switching the suction mode, and a temperature setting lever 6 for setting the temperature in the passenger compartment to a desired temperature.
3, an air volume switching lever 64 for switching the air flow rate of the centrifugal fan 31, and air outlet switching switches 65 to 70 for switching the air outlet mode.

Of these, the A / C switch 60 is an operation switch of the air conditioner for instructing a cool mode in which the comfort inside the vehicle is emphasized. Further, the ECO switch 61 is an economy mode in which the degree of cooling of the conditioned air by the evaporator 45 is set lower than in the cool mode to perform air conditioning, specifically, the ON / OFF temperature of the compressor 41 is set to 4 in the cool mode.
℃ ON, 3 ℃ OFF, 13 ℃ ON, 12 ℃ OF
It is an operation switch of the air conditioner for instructing the economy mode in which importance is attached to fuel economy (fuel economy).

The air volume switching lever 64 is used for the blower motor 32.
Position to stop energization to the blower motor 32, AUTO position to automatically control the blower motor 32 blower voltage, LO position to minimize the blower voltage applied to the blower motor 32 to the minimum air volume, and blower voltage applied to the blower motor 32 to an intermediate value. It is possible to operate in the ME position where the air flow rate is intermediate and the HI position where the blower voltage applied to the blower motor 32 is maximized to maximize the air flow rate.

The outlet switch is a face (FACE) switch 65 for fixing in the FACE mode,
A high level (B / L) switch 66 for fixing the B / L mode, a foot (FOOT) switch 67 for fixing the FOOT mode, and a foot differential (F / D) switch 68 for fixing the F / D mode. , Defroster (DEF) switch 69 for fixing in DEF mode,
And the automatic (A
There is a UTO) switch 70.

As shown in FIG. 2, the respective sensors are an inside air temperature sensor 71 for detecting the air temperature inside the vehicle compartment (hereinafter referred to as the inside air temperature) and an air temperature outside the vehicle interior (hereinafter referred to as the outside air temperature). Outside temperature sensor 72, solar radiation sensor 73 for detecting the amount of solar radiation applied to the vehicle interior, evaporator 45
After-evaporation temperature sensor 74 for detecting the air cooling temperature of the vehicle, a cooling water temperature sensor 75 for detecting the temperature of the engine cooling water flowing into the heater core 51 (cooling water temperature), a vehicle speed sensor 76 for detecting the vehicle speed of the vehicle 5, the inside air and A humidity sensor (inside air humidity sensor, outside air humidity sensor) 77 that detects the relative humidity of the outside air, a window glass temperature sensor 78 that detects the temperature of the windshield 3, and a carbon dioxide concentration in the vehicle interior air (inside air). CO ₂ sensor (CO ₂ concentration detection means)
There are 79 mag.

Of these, the post-evaporation temperature sensor 74 is specifically arranged at a portion immediately after the evaporator 45, and is composed of a thermistor for detecting the air temperature immediately after passing through the evaporator 45 (hereinafter, referred to as post-evaporation temperature). . Further, the humidity sensor 77 is
It is arranged in the air flow upstream side portion of the centrifugal fan 31 in the air passage 10a, and for example, it is suitable to arrange the humidity sensor 77 at the suction port of the fan 31. This allows
The relative humidity of the inside air is detected in the inside air mode, and the relative humidity of the outside air is detected in the outside air mode. If an infrared sensor is used as the window glass temperature sensor 78, the window glass temperature can be accurately detected, which is preferable.

Next, the control processing of the air conditioner ECU 2 of this embodiment will be described with reference to FIGS. 4 to 7. here,
FIG. 4 is a flowchart showing the basic control processing by the air conditioner ECU 2.

Inside the air conditioner ECU 2, a microcomputer including a CPU, a ROM, a RAM and the like (not shown) is provided, and sensor signals from the respective sensors 71 to 79 are A / A by an input circuit (not shown) in the air conditioner ECU 2. After being D-converted, it is input to the microcomputer.

First, when the ignition switch is turned on and DC power is supplied to the air conditioner ECU 2, the routine of FIG. 4 is started to perform each initialization and initial setting (step S1).

Next, switch signals and the like are read from the switches such as the temperature setting lever 63, and the inside air temperature sensor 71, the outside air temperature sensor 72, the solar radiation sensor 73, the post-evaporation temperature sensor 74, the cooling water temperature sensor 75, the vehicle speed. A / D sensor signals from the sensor 76 and the humidity sensor 77
After conversion, it is read (step S2).

Subsequently, the target outlet temperature (TAO) of the air blown into the vehicle compartment is calculated based on the following equation 1 stored in the ROM in advance (step S3).

[0049]

[Equation 1] TAO = KSET × TSET-KR × TR-K
AM × TAM−KS × TS + C where TSET is the set temperature set by the temperature setting lever 63, TR is the inside air temperature detected by the inside air temperature sensor 71, TAM is the outside air temperature detected by the outside air temperature sensor 72, and TS is It is the amount of solar radiation detected by the solar radiation sensor 73.
Also, KSET, KR, KAM and KS are gains,
C is a constant for correction.

Next, the suction mode is determined to be either the inside air mode or the outside air mode (step S4). The inside air mode is a suction port mode in which the inside / outside air switching damper 13 is set at the position indicated by the chain double-dashed line in FIG. 1 to suck the inside air from the inside air suction port 11. Further, the outside air mode is a suction mode in which the inside / outside air switching damper 13 is set to the position indicated by the solid line in FIG. 2 to suck outside air from the outside air suction port 12.

Then, during the heating operation in which the drive of the compressor 41 is stopped, the suction port mode is set to the outside air mode. On the other hand, during the cooling operation in which the compressor 41 is driven to cool the air by the evaporator 45, the suction port mode is determined based on the flowchart shown in FIG. 7 described later.

Next, the blower voltage (voltage applied to the blower motor 32) corresponding to the target blowout temperature is determined from the characteristic diagram (see FIG. 5) stored in advance in the ROM (step S5). Here, when the inlet mode is determined to be the outside air mode in step S4, the characteristic map shown by the solid line A in FIG. 5 is adopted. On the other hand, when the suction port mode is determined to be the inside air mode, the characteristic map shown by the dotted line B in FIG. 5 that is offset in the direction in which the blower voltage becomes smaller than the characteristic map of the solid line A is adopted. In addition, when the air volume switching lever 64 is manually selected, the selected air volume is set.

Next, when the auto switch 70 is operated to select the auto mode, the blowing mode corresponding to the target blowing temperature is determined from the characteristic diagram (see FIG. 6) stored in advance in the ROM (see FIG. 6). Step S6). This blowout mode is switched and set as face mode → bilevel mode → foot mode as the target blowout temperature rises from the low temperature side to the high temperature side. The outlet switch 65
When any one of to 69 is manually selected, the selected outlet mode is set.

Next, the following equation 2 stored in advance in the ROM
The target damper opening degree (SW) of the air mix damper 52 is calculated based on the formula (step S7).

[0055]

[Expression 2] SW = {(TAO-TE) / (TW-TE)}
× 100 (%) TE is the post-evaporation temperature detected by the post-evaporation temperature sensor 74, and TW is the cooling water temperature detected by the cooling water temperature sensor 75.

Then, when calculated as SW ≦ 0 (%), the air mix damper 52 is at a position (MAX) where all the cool air from the evaporator 45 is diverted from the heater core 51.
(COOL position). Also, SW ≧ 100
When calculated as (%), the air mix damper 52
Is controlled to a position (MAXHOT position) where all the cool air from the evaporator 45 is passed to the heater core 51. Furthermore, 0
When calculated as (%) <SW <100 (%), the air mix damper 52 causes a part of the cool air from the evaporator 45 to pass through the heater core 51 and the rest of the cool air as the heater core 51.
The position is controlled to detour from.

Next, ON-OFF of the compressor 41 is decided (step S8). Specifically, the target evaporator outlet temperature TEO is calculated based on the above TAO and the outside air temperature TAM,
Actual evaporator outlet temperature TE and target evaporator outlet temperature TEO
And when TE> TEO, turn on the compressor,
When TE ≦ TEO, the compressor is turned off.

Next, control signals are output to the actuators 14, 22, 53, the blower drive circuit 33, and the clutch drive circuit 47 so that the control states calculated or determined in steps S3 to S8 can be obtained. Yes (step S9).

Next, the suction port mode determination flow during the cooling operation in step S4 will be described with reference to FIG.

First, the outside air mode is forcibly switched to introduce the outside air into the inlet switching box 10b, and the state of the outside air mode is maintained for a predetermined time (for example, about 10 seconds) (step S40).

Then, while reading the relative humidity (outside air humidity) RHo detected by the humidity sensor 77 and the outside air temperature TAM detected by the outside air temperature sensor 72,
The enthalpy io of the outside air is calculated based on the relative humidity RHo and the outside air temperature TAM (step S4).
1). Specifically, a well-known moist air diagram is stored in advance in the ROM, and the enthalpy io of the outside air can be calculated from the relative humidity RHo of the outside air and the outside air temperature TAM on the moist air diagram.

Next, the inside air mode is forcibly switched to introduce the inside air into the suction port switching box 10b, and the state of the inside air mode is maintained for a predetermined time (for example, about 10 seconds) (step S42).

Then, the relative humidity (inside air humidity) RHr detected by the humidity sensor 77 and the inside air temperature TR detected by the inside air temperature sensor 71 are read, and the inside air is calculated based on these relative humidity RHr and inside air temperature TR. The enthalpy ir of is calculated (step S43).
Specifically, the enthalpy io of the inside air can be calculated from the relative humidity RHr of the inside air and the inside air temperature TR on the aforementioned moist air diagram.

Next, the enthalpy io of the outside air and the enthalpy ir of the inside air are compared in magnitude (step S4).
4). If the enthalpy ir of the inside air is equal to or lower than the enthalpy io of the outside air (ir ≦ io), the CO ₂ concentration detected by the CO ₂ sensor 79 is a predetermined value (for example, 0.
17%) or less (step S4)
5). Further, if the CO ₂ concentration is equal to or lower than the predetermined value, it is estimated whether or not the window glass 3 is in a fog-prone state (step S46). Yes (step S4
7).

On the other hand, if the CO ₂ concentration is higher than the predetermined value in step S45, or if it is estimated that the cloudiness is likely to occur in step S46, the suction mode is set to the outside air mode (step S49). .

Further, in step S44, the enthalpy io of the outside air is smaller than the enthalpy ir of the inside air (io <
In the case of ir), the deviation (| Tset-TR |) between the set temperature Tset and the inside air temperature TR is a predetermined value (for example, 3 ° C.).
It is determined whether or not it is larger (step S48). Then, when the deviation between the set temperature Tset and the inside air temperature TR is larger than a predetermined value (| Tset-TR |> 3), it is considered that the cool down control is being performed, and the suction port mode is set to the inside air mode. (Step S47).

On the other hand, when the deviation between the set temperature Tset and the inside air temperature TR is less than or equal to a predetermined value (| Tset-TR |
For ≦ 3), assuming that the cooldown control is not in progress,
The intake mode is set to the outside air mode (step S4)
9).

When the suction port mode is determined in steps S47 and S49, a predetermined time (for example, 10 minutes)
Maintains the determined inlet mode. That is, step S4 is skipped until a predetermined time elapses, and the process proceeds from step S3 to step S5. Then, after a lapse of a predetermined time, both enthalpies io and ir are compared again in step S4 to determine the suction port mode.

Therefore, when the mode is switched to one of the suction port modes, the other mode is set to, for example, 1
It switches periodically in 0 minutes (steps S40, S4
2). Further, since the humidity sensor 77 is arranged in the air flow upstream side portion of the centrifugal fan 31 in the air passage 10a, the outside air humidity RHo and the inside air humidity RHr before and after the switching are respectively detected by this one humidity sensor 77. (Steps S41 and S43), both enthalpies ir and io are periodically compared in magnitude (step S44).
It will be.

When the suction port changeover switch 62 is manually selected, the selected suction port mode is set.

Next, the operation of the vehicle air conditioner having the above-mentioned structure will be briefly described.

When the A / C switch 60 or the ECO switch 61 is turned on, the operation and stop of the compressor 41 are controlled so that the post-evaporation temperature TE becomes a predetermined temperature, and the air sucked into the air conditioning duct 10 is removed. After being cooled when passing through the evaporator 45, it is reheated when passing through the heater core 51 and adjusted so that the temperature of the air blown into the vehicle interior becomes the target blowout temperature TAO. As a result, the temperature inside the vehicle compartment is controlled to the set temperature TSET set by the occupant operating the temperature setting lever 63.

As described above, according to the present embodiment, in step S4, the enthalpies ir and io of the inside air and the outside air are calculated during the cooling operation, the calculated enthalpies ir and io are compared in magnitude, and the suction port mode is switched. Is automatically controlled so as to introduce the air having the smaller enthalpy of the inside air and the outside air. Therefore,
Since the air having the smaller enthalpy is introduced from the inside air and the outside air, the engine 6 serving as the drive source of the compressor 41
It is possible to surely save the power consumption.

Here, at the time of cool down, the compressor 41
By saving the power of the engine 6 that is the drive source of
There are cases where it is desired to give priority to lowering the vehicle interior temperature TR in a short time. In contrast to this case, according to the present embodiment, even if io <ir in step S44, the mode is set to the inside air mode if it is determined in step S48 that the cooldown has occurred. Therefore, both enthalpies ir, io The inside air mode is set irrespective of the size, and the reduction of the vehicle interior temperature TR in a short time can be prioritized, which is preferable.

Further, according to this embodiment, in the normal cooling operation other than the cool down, in most cases, ir ≦
It becomes io, and if steps S45 and S46 are not performed, the cooling operation is performed in the internal air mode for a long time. However,
When the inside air mode is continued for a long time, fog on the window glass and an increase in carbon dioxide concentration in the vehicle compartment become problems.

On the other hand, in the present embodiment, step S4
5 and S46, and ir ≦ i in step S44.
Even if it is o, if the carbon dioxide concentration is higher than the predetermined value in step S45 or if it is determined in step S46 that the window glass is likely to be fogged, the outside air mode is set.
It is possible to save the power of the engine 6 that is the drive source of the compressor 41 while preventing the window glass from fogging and suppressing the increase in the carbon dioxide concentration in the vehicle interior.

Here, in order to confirm the effect of this power saving, the present inventor has determined the heat load (cooling load) of the vehicle during the cooling operation when the vehicle is stopped, when traveling at a speed of 40 km / h in the inside air mode, and in the outside air mode. Was measured in each state when running at 40 km / h. As the experimental conditions, the outside air temperature was 35 ° C,
The relative humidity of the outside air is 60% RH, the amount of solar radiation is 1000 W / m ² , the vehicle interior temperature when the vehicle is stopped is 30 ° C., and the vehicle interior temperature when the vehicle is traveling is 25 ° C. Also, the number of passengers when traveling is one.

The bar graph shown in FIG. 8 shows the results of the above-described experiment. In the figure, the symbol A is the heat load due to the solar radiation radiated from the vehicle glass into the vehicle interior, and the symbol B is the vehicle body to the vehicle. Heat load due to heat transfer to the room, code C
Is a heat load due to the vehicle becoming a heat mass when the vehicle is stopped, reference character D is a heat load due to ventilation loss in which inside air and outside air are exchanged during traveling, and reference sign E is a heat load due to heat generation of an occupant.

As shown in the experimental results, about half of the heat load of the vehicle in the outside air mode is the heat load due to the ventilation loss D, and the total heat load in the inside air mode (2900 W).
Is about half of the total heat load (6120 W) in the outside air mode. Therefore, according to the present embodiment in which the cooling operation is performed in the inside air mode for a long time, the power saving of the drive source of the compressor 41 can be significantly improved.

Further, according to this embodiment, when one of the suction port modes is switched to, the other mode is periodically switched. And the humidity sensor 7
Since 7 is arranged in the air flow upstream side portion of the centrifugal fan 31 in the air passage 10a, the outside air humidity RHo and the inside air humidity RHr before and after the switching can be detected by this one humidity sensor 77, respectively. . Therefore, the number of parts can be reduced and the cost can be reduced as compared with an air conditioner including one inside air humidity sensor and one outside air humidity sensor.

Even when the inside air mode is continued for a long time, the passenger's thirst does not pose a problem. Specifically, it has been confirmed by experiments that even if the relative humidity RHr in the passenger compartment is 0%, the passenger does not feel thirsty for at least 3 hours after the last hydration of the occupant.

(Other Embodiments) In step S47 shown in FIG. 7 of the above embodiment, the inside / outside air switching damper 13 is set to the inside air mode in which it is set to the position indicated by the chain double-dashed line in FIG. 1, but the present invention is not limited to this. Instead, in step S47, for example, the inside / outside air switching damper 13 is set to a position slightly closer to the solid line position from the two-dot chain line position in FIG. 1 to set the partial outside air mode in which a part of the outside air is introduced in addition to the inside air. You may do it.

Further, the humidity sensor 7 in the above embodiment.
7 may be a temperature / humidity sensor, and the inside air temperature sensor 71 and the outside air temperature sensor 72 may be eliminated.

Although the flow chart shown in FIG. 7 of the above embodiment includes steps S45, S46 and S48, these steps may be omitted. Further, any of these steps may be selected and provided.

In the above embodiment, the humidity sensor 77 detects the humidity RHr and RHo of the inside air and the outside air. However, the humidity sensor for detecting the inside air humidity RHr and the outside air humidity RHo are detected. The humidity sensor may be separately provided. In this case, it is possible to eliminate the need to periodically switch to the other mode and simplify control. Also, the enthalpy of shyness i
It is possible to compare r and the enthalpy io of the outside air at any time.

In the above embodiment, the suction port mode is determined on the basis of the flowchart shown in FIG. 7 during the cooling operation in which the compressor 41 is driven and the evaporator 45 cools the air. The inlet mode may be determined based on the flowchart shown in FIG. 7 during the cooling operation in which the outlet temperature TAO is equal to or higher than a predetermined temperature (for example, −20 ° C.).

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a vehicle air conditioner showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a control system of the air conditioner of FIG.

FIG. 3 is a diagram showing details of a control panel of FIG.

4 is a flowchart showing a basic control process by the air conditioner ECU of FIG.

FIG. 5 is a characteristic diagram showing a relationship between a target outlet temperature and a blower voltage.

FIG. 6 is a characteristic diagram showing a relationship between a target outlet temperature and an outlet mode.

FIG. 7 is a flowchart showing details of the suction port mode determination step of FIG.

FIG. 8 is a graph showing an experimental result for confirming the effect of power saving of the present invention.

[Explanation of symbols]

10 ... Air conditioning duct, 10a ... Air passage, 41 ... Compressor,
45 ... Evaporator, ir ... Enthalpy of inside air, io ... Enthalpy of outside air.

Claims (8)

[Claims] 1. An air conditioning duct (10) forming an air passage (10a) through which air is blown into a vehicle compartment, and an evaporator (45) arranged in the air passage (10a) to cool the air. And a compressor (41) that compresses and discharges the refrigerant that has passed through the evaporator (45), and an inside air mode that introduces inside air into the air passage (10a) and outside air into the air passage (10a). In an air conditioner for a vehicle capable of automatically controlling switching between an intake mode and an outside air mode, the inside air is cooled during a cooling operation in which the compressor (41) is driven to cool the air by the evaporator (45). Enthalpy (ir) and outside air enthalpy (io) are calculated, the calculated two enthalpies (ir, io) are compared in magnitude, and the suction port mode is switched between inside and outside air. An air conditioner for a vehicle, which is automatically controlled so that the air with the smaller enthalpy is introduced. 2. The inside air temperature (T) detected by an inside air temperature sensor (71) is the enthalpy (ir) of the inside air.
R) and the inside air humidity (RHr) detected by the inside air humidity sensor (77), and the enthalpy (io) of the outside air is calculated as the outside air temperature (TAM) detected by the outside air temperature sensor (72). Outside air humidity (RHo) detected by outside air humidity sensor (77)
The air conditioner for a vehicle according to claim 1, wherein the air conditioner is calculated based on 3. The inside air humidity sensor and the outside air humidity sensor are an inside air introduction port (11) and an outside air introduction port (12).
It is the same one humidity sensor (77) arranged inside the inside / outside air switching box (10b) formed with the other mode when the mode is switched to one of the suction port modes. It is possible to periodically compare the two enthalpies (ir, io) by periodically switching to (1) and detecting humidity (RHo, RHr) before and after switching by the one humidity sensor (77). The vehicle air conditioner according to claim 2, which is characterized in that. 4. A characteristic map showing a change in the blown air volume of the air corresponding to a change in the target blown air temperature (TAO) of the air blown into the vehicle compartment, wherein the blown air volume is automatically adjusted based on the characteristic map. It is controllable, and the characteristic map in the inside air mode is offset in a direction in which the blown air volume becomes smaller than the characteristic map in the outside air mode. The vehicle air conditioner according to any one of 3 above. 5. A set temperature (Tse set by an occupant)
5. When the deviation between t) and the inside air temperature (TR) is larger than a predetermined value, the inside air mode is switched regardless of the magnitude of the both enthalpies (ir, io). The vehicle air conditioner according to any one of the above. 6. Estimating whether or not the window glass (3) of the vehicle is easily fogged, and when it is presumed that the window glass (3) is easily fogged, regardless of whether the enthalpies (ir, io) are large or small. The vehicle air conditioner according to any one of claims 1 to 4, wherein the vehicle air conditioner is switched to the outside air mode. 7. An infrared sensor (78) for detecting the temperature of a window glass (3) of a vehicle, the window glass temperature detected by the infrared sensor (78) and the inside air humidity sensor (77). Based on the inside air humidity (RHr), it is estimated whether or not the window glass (3) is in a fog-prone state, and when it is estimated that the window glass (3) is in a fog-prone state, the both enthalpies (ir, io) are The air conditioner for a vehicle according to any one of claims 2 to 4, wherein the air conditioner is switched to the outside air mode regardless of the size. 8. CO for detecting the concentration of carbon dioxide in the inside air
_When the carbon dioxide concentration detected by the CO ₂ concentration detecting means is larger than a predetermined value, the mode is switched to the outside air mode regardless of the magnitude of the both enthalpies (ir, io). The vehicle air conditioner according to any one of claims 1 to 4.