JPH0834226A - Air conditioner for vehicle - Google Patents

Abstract

PURPOSE:To provide an air conditioner for a vehicle which does not use an expensive humidity sensor, and can make both power saving and fog prevention of a window glass pane compatible, and can decrease the number of times of on-off changing of a compressor for reducing the deterioration of occupant's riding comfort. CONSTITUTION:In the case where a control device 40 actuates a wiper according to a wiper switch 41 and a solar radiation sensor 42, and the quantity of solar radiation is judged to be less than fixed quantity, the cooling capacity of an evaporator 32 is enlarged to lower the dew point of outlet air of the evaporator 32 for carrying out the control for preventing the window glass fogging, and in other cases, the cooling capacity of the evaporator 32 is reduced to carry out power saving control.

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, and more particularly to a vehicle air conditioner which achieves both power saving and window glass fogging prevention.

[0002]

2. Description of the Related Art In many vehicle air conditioners, the air for air conditioning is cooled by a heat exchanger for cooling (evaporator), and a part of the cooled air is heated by a heat exchanger for heating (heater core) to control the temperature. You are in control. As a modification of this,
There are 3364 and Japanese Patent Laid-Open No. 4-260813. These control the capacity of the compressor that compresses the refrigerant flowing to the evaporator to prevent the air-conditioning air from being cooled more than necessary by the evaporator, and reduce the amount of heat removed here to heat the heater core. It is designed to be reduced or eliminated.

However, these are not a problem on a sunny day, but if the capacity of the compressor is controlled to be small in rainy weather with high humidity, the temperature of the air conditioning air at the outlet of the evaporator rises, and The amount of dehumidification may be insufficient and the window glass of the vehicle may become cloudy.

As an attempt to solve this, Japanese Patent Laid-Open No. 59-14564, Japanese Patent Laid-Open No. 2-249716, Japanese Patent Laid-Open No. 4-349014, and Japanese Patent Laid-Open No. 5-34 are known.
5515, JP-A-5-124424 and the like.

In Japanese Patent Laid-Open No. 59-14564, it is judged that the humidity of the outside air is high when the wiper is operating, and the operating outside air temperature of the compressor, that is, the temperature at which the compressor is stopped, is set to a low value, and the air cooled by the evaporator is The temperature is lowered and the dehumidification amount is increased to prevent fogging of the window glass. On the other hand, when the wiper is not operating, the compressor operating outside air temperature is set high to save power.

Further, in Japanese Patent Laid-Open No. 2-249716, the on / off set temperature of the compressor is controlled in a predetermined pattern depending on the operating condition of the wiper and the environmental conditions (temperature conditions) inside and outside the vehicle. When the outlet air temperature of the evaporator is higher than this on / off set temperature, the compressor is turned on, and when it is low, it is turned off.

For example, when the wiper switch is off, the compressor on / off set temperature is controlled from a maximum of 12 ° C. in a predetermined pattern based on the temperature inside and outside the vehicle, the outlet air temperature of the evaporator, and the temperature set inside the vehicle. In addition, when the wiper operation is intermittent operation, the maximum temperature is 8 ° C, when the wiper operation is low speed operation, the maximum is 6 ° C, and when the wiper operation is high speed operation, the maximum is 4 ° C. Controlled by patterns. In this example, whether the humidity inside or outside the vehicle is high or low is determined by the operation state of the wiper, and the operation of the compressor is adjusted to achieve both power saving and prevention of fogging of the window glass.

Further, in JP-A-4-349014 and JP-A-5-345515, the target humidity of the air blown into the passenger compartment is calculated, and the operation of the compressor is adjusted on the basis of the target humidity to save the power of the air conditioner. We are trying to prevent fogging of the window glass at the same time.

Once the target outlet humidity is calculated, the dew point temperature for it is determined, and the compressor may be turned on / off or the capacity of the variable capacity compressor may be controlled so that the air temperature at the outlet of the evaporator is below the dew point temperature.

Next, in Japanese Unexamined Patent Publication No. 5-124424, the amount of air from the defroster outlet is increased according to the low speed operation to the high speed operation of the wiper operation to prevent the fogging of the window glass.

[0011]

However, there are various cases in which the wiper is used depending on weather conditions, vehicle use conditions, and the like. For example, in the case of clearing up after rainy weather, it is conceivable that water may be splashed by an oncoming vehicle or an overtaking vehicle or splashed by the tires of the preceding vehicle. At this time, a wiper is used temporarily, but because the sunlight raises the temperature of the window glass and the water on the window glass is temporary, the temperature of the window glass does not drop so much due to the heat capacity of the window glass. , Fogging of the window glass hardly occurs.

Therefore, in such a case, Japanese Patent Laid-Open No. 59-
There is no need to reduce the operating outside air temperature of the compressor to increase the operation of the compressor as in Japanese Patent No. 14564.
There is no need to decrease the compressor on / off set temperature from 12 ° C. to 8 ° C. and increase the operation of the compressor just because the wiper is in the operating state as in JP-A-2-249716.

Also, even in the case of light rain, when there is sunshine,
Even when a wiper is used, cloudiness is different when it is slightly cloudy and when there is no sunlight. Therefore, when there is sunlight, it is not necessary to increase the operation of the compressor as in JP-A-59-14564 and JP-A-2-249716.

Further, in the cases of JP-A-59-14564 and JP-A-2-249716, the compressor operates when the occupant operates the wiper. At this time,
Not only the compressor power increases, but also the following problems occur.

When the compressor is on and off, the idle speed of the engine that drives it is changed. That is, when the compressor is on, the idling speed is set higher than when the compressor is off so that the engine will not stall due to its load and the idle vibration will not increase.

For this reason, especially in low speed operation (congestion operation), when the compressor is turned on or off, the engine speed increases or decreases, which causes a change in vehicle speed and a change in engine sound during congestion. Deteriorates passenger comfort.

Further, in both JP-A-4-349014 and JP-A-5-345515, if it is attempted to achieve both sufficient power saving and fogging prevention, the conditions under which the window glass will not fog are calculated. Requires an expensive humidity sensor. If the humidity sensor is not used and the humidity is assumed to be a certain value, the control accuracy will deteriorate, and if fogging prevention is prioritized, the cooling capacity will always be increased (the compressor capacity etc. will be increased). Power saving becomes insufficient even in fine weather.

In the case of Japanese Unexamined Patent Publication No. 5-124424, the temperature of the occupant's head rises due to an increase in the amount of defroster air, which impairs the temperature distribution of head cold foot heat and also deteriorates the riding comfort of the occupant.

The present invention has been made in view of the above conventional problems, and an object thereof is to use an expensive humidity sensor,
An object of the present invention is to provide a vehicle air conditioner that can both reduce power consumption and prevent fogging of window glass, reduce the chances of switching the compressor on and off, and reduce the deterioration of passenger comfort.

[0020]

In order to achieve the above object, the present invention provides a cooling capacity control means for controlling the cooling capacity of a cooling heat exchanger for cooling air conditioning air, and an operation of a wiper. The wiper operation detecting means for detecting, the solar radiation amount detecting means for detecting the amount of solar radiation, and the cooling capacity control means for reducing the cooling capacity based on the detection results of the wiper operation detecting means and the solar radiation amount detecting means, and power saving control. Or having a determination means for determining whether to increase the cooling capacity to perform the fogging prevention control of the window glass, the wiper is activated, and the amount of solar radiation is a predetermined amount or less, the cooling capacity control means It is characterized in that the cooling capacity of the heat exchanger for cooling is increased to perform window glass fogging prevention control, and in other cases, the cooling capacity is reduced to perform power saving control.

[0021]

According to the above construction, the wiper is operating,
And if the amount of solar radiation is below a certain amount, the window glass is likely to fog, so the cooling capacity will be large.On the other hand, even if the wiper is not operating or the wiper is operating, if the amount of solar radiation is above a certain value the window Since the cloudiness of the glass does not easily occur, the cooling capacity is not increased and the same control as when the wiper is not activated is performed.

Generally, when the cooling capacity is controlled by the compressor capacity, the vehicle interior humidity is required in the process of calculating the compressor required capacity, but the vehicle interior humidity is used as a substitute in order to prevent the fogging of the window glass. May be controlled.

Therefore, according to the present invention, the target outlet humidity is not calculated when it is sunny without using the wiper or when the amount of solar radiation is large and the window glass is not easily fogged even if the wiper is used.
Calculate the required capacity of the compressor to bring the cabin temperature to the set temperature and reduce the compressor operation to save power. On the other hand, when a wiper is used and the amount of solar radiation is below a predetermined value, the window glass tends to become cloudy. Therefore, in this case as well, the target outlet humidity is not calculated and the cooling capacity is increased (maximum capacity control, etc.) to become cloudy. To prevent. This allows
It is possible to achieve both power saving and prevention of fogging of the window glass without the need for an expensive humidity sensor.

Further, even if the wiper is operated, if the amount of solar radiation exceeds a predetermined value, the compressor does not operate, so there is less opportunity to switch the compressor on and off, and deterioration of the ride comfort of the occupant can be reduced.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 shows a block diagram of a vehicle air conditioner of this embodiment.

In FIG. 1, the ventilation duct 10 has air intakes 21, 22, 23, 24 at one end, a fan 11 is arranged immediately after the air intakes 21, 22, 23, 24, and the other end. The air is blown toward the air outlets 25, 26, and 27. The fan 11 is driven by the electric motor 12,
The rotation speed of the electric motor 12 is controlled by a fan speed control device 36 that receives a command from the control device 40. in this case,
The fan speed control device 36 may be composed of transistors, and at that time, the fan speed is duty controlled.

The air intakes 21, 22, 23, 24 are the air intakes 21, 22 for taking in the air in the passenger compartment.
And the outside air intakes 23 and 24 for taking in outside air. Inside air intakes 21, 22 and outside air intakes 23, 2
4 is opened / closed by inside / outside air switching dampers 13 and 14, respectively, and it is possible to switch between the air intake (inside air intake) in the vehicle interior and the outside air intake.

Further, the air intake ports 21, 22, 23, 24
The inside / outside air switching damper 13 opens the vehicle interior air intake 21 and the outside air intake 23, and the inside / outside air switching damper 14 opens the outside air intake 24 and the vehicle interior air intake 22.
Both inside and outside air can be taken in by closing. That is, the inside and outside air can be mixed.

The inside / outside air switching dampers 13 and 14 are moved by actuators 15 and 16 based on a command from the control device 40. Further, an evaporator 32, which is a heat exchanger for cooling, is arranged downstream of the fan 11 over the entire cross section of the ventilation duct 10 to cool the passing air.

Further downstream, a heater core 30 as a heat exchanger for heating is arranged so as to occupy a part of the cross section of the ventilation duct 10, and a rotary shaft of an air mix damper 31 is arranged at one end of the heater core 30. Air mix damper 3
By changing the rotation angle of 1, the ratio of the air flowing through the ventilation duct 10 to the air passing through the heater core 30 and the air bypassing the heater core 30 can be changed from 0 to 100%. The rotation angle of the air mix damper 31 is changed by the air mix damper actuator 37 based on a command from the control device 40.

The current angle with respect to the maximum rotation angle of the air mix damper 31 is called the opening of the air mix damper 31 (when the heater core is fully closed, it is called 0).

A vent outlet 25 is provided on the downstream side.
, A heater outlet 26, and a defroster outlet 27 are arranged. Air is blown mainly from the vent outlet 25 toward the upper half of the occupant, from the heater outlet 26 toward the feet of the occupant, and from the defroster outlet 27 toward the front window.

Vent outlet 25 and defroster outlet 27
Are switched by the switching damper 17, and the heater outlet 26 is opened and closed by the switching damper 18.

Then, the evaporator 32 and the condenser 3
3, compressor 34 and expansion valve 35
A refrigeration cycle is constituted by.

The above-mentioned control device 40 constitutes the judgment means and the cooling capacity control means of the present invention, and includes the wiper switch 4
1, a predetermined input from the solar radiation sensor 42, the outside air temperature sensor 43, the vehicle interior temperature sensor 44, the evaporator air temperature sensor 45, the temperature setting device 46, the condenser pressure sensor 51, the evaporator pressure sensor 52, and the rotation sensor 53. Receiving various controls. The wiper switch 41 constitutes the wiper operation detecting means of the present invention, and the solar radiation sensor 42 constitutes the solar radiation amount detecting means of the present invention.

FIG. 2 shows a block diagram of the configuration of this embodiment.

In FIG. 2, the wiper operation detecting means is
Information about whether the wiper is operating or not is transmitted to the judging means. Further, the solar radiation amount detecting means detects the solar radiation amount and transmits the value to the judging means.

The judgment means gives an instruction to the cooling capacity control means based on the information from the wiper operation detection means and the solar radiation amount detection means.

That is, when the judging means receives the information indicating that the wiper is not operating from the wiper operation detecting means, it is considered that the window glass is not easily fogged by water vapor, such as when the weather is fine. Therefore, in this case, it is not necessary to cool the air-conditioning air to a low temperature by the evaporator 32 and lower the dew point to prevent the fogging of the window glass. For this reason, the determination means gives an instruction to the cooling capacity control means to reduce the cooling capacity of the evaporator 32 and perform power saving control.

Even when the wiper is operating, the temperature of the window glass is high when the amount of solar radiation outside the vehicle is equal to or more than the predetermined value by the solar radiation amount detecting means, and the window glass is the same as above. Is considered to be in a state of being hardly clouded by water vapor. Therefore, in this case as well, there is little need to perform the operation for preventing fogging, and the determination means issues an instruction to perform power saving control.

On the other hand, when the wiper is activated and the amount of solar radiation is less than the predetermined value, it is considered that the humidity inside and outside the vehicle is high and the temperature of the window glass is low, such as in rainy weather.
Therefore, it is necessary to cool the air-conditioning air to a low temperature by the evaporator 32 and lower its dew point to prevent fogging of the window glass. For this reason, the determination means gives an instruction to the cooling capacity control means to increase the cooling capacity of the evaporator 32 and perform the window glass fogging prevention control.

FIG. 3 shows a flowchart of the operation concept of the embodiment shown in FIG.

In FIG. 3, when the power is turned on, the operation starts in step 60, and in step 61, the wiper operation detecting means detects the operation or non-operation of the wiper.

If the wiper is inactive, the determination means causes the cooling capacity control means to perform power saving control in step 62.

On the other hand, when the wiper is activated in step 61, it is determined in step 63 whether or not the amount of solar radiation outside the vehicle is equal to or greater than the predetermined value S _L by the amount of solar radiation detection means. When the amount of solar radiation is equal to or greater than the predetermined value S _L , the process proceeds to step 62 similarly to the above, and power saving control is performed.

When the amount of solar radiation is less than the predetermined value S _L , the determination means causes the cooling capacity control means to perform the window glass fogging prevention control in step 64.

Finally, in step 65, the process returns to step 60 and the above operation is repeated.

FIG. 4 is a flow chart showing an example of control by the control device 40 of this embodiment.

[0050] In FIG. 4, starts when the power is put in step 100, the outside air temperature T _o of the outside air temperature sensor 43 is detected in step 102 reads the value of various sensors such as the outside air temperature sensor 43 at step 101, vehicle The vehicle interior temperature T _r detected by the indoor temperature sensor 44 and the solar radiation sensor 4
The solar radiation amount ST detected by 2 and the set temperature T _set from the temperature setting device 46 are input, and the target blow-out temperature T _ao required to set the vehicle interior temperature to the set temperature T _set from those information.
Is calculated by the equation (1).

[0051]

[ _Equation 1] T _ao = K ₁ · T _set −K ₂ · T _r −K ₃ · T _o −K ₄ · ST + C ₁ (1) where K ₁ , K ₂ , K ₃ , K ₄ , K ₁ Is a constant.

In step 103, it is determined from the wiper switch 41 whether the wiper is operating or not operating. As described above, when the wiper is not operating, it is considered that the humidity inside and outside the vehicle is not high and the window glass is unlikely to be fogged. Therefore, the air conditioner can be made to perform the power saving control described above.

In this case, in step 107, the compressor on / off set temperature is set to T _ao described above. As a result, the compressor 34 is turned on when the temperature of the after-evaporator air temperature sensor 45 is higher than T _ao , and is turned off when it is lower than T _ao , and the after-evaporator air temperature is maintained at the target outlet temperature T _ao . That is, in this embodiment, the compressor is on / off controlled.

Then, in step 106, the opening degree of the air mix damper 31 is controlled. In this case, for example the opening 0, that is the case, such as in the summer outside air temperature T _o and the vehicle interior temperature T _r higher than the target outlet air temperature T _ao, the air mix damper 31
Is fully closed, all the heater cores 30 are bypassed, and air is blown out from either of the air outlets 25 and 26 as it is, so that the vehicle interior temperature can be maintained at the set temperature T _set . As a result, it is possible to prevent excessive cooling by the evaporator 32,
It is possible to save power by eliminating the need for extra heating in the heater core 30.

On the other hand, when the outside air temperature T _o and the passenger compartment temperature T _r are lower than the target outlet air temperature T _ao in winter, the compressor is always off, and the outlet air temperature is adjusted only by adjusting the opening of the air mix damper 31. Can be maintained at the target outlet temperature T _ao . As a result, the compressor can be turned off, which saves power.

When the wiper is operating in step 103, it is determined in step 104 whether the amount of solar radiation detected by the solar radiation sensor 42 is less than or equal to a predetermined value S _L.

When the value is larger than the predetermined value S _L, it is considered that the window glass is less likely to be fogged even when the wiper is operating. Therefore, in this case as well, the power saving control of the air conditioner can be performed. Therefore, in step 107, the compressor on / off set temperature is set to T _ao . After that, the power saving control is performed by the control described above.

When the amount of solar radiation is below the predetermined value S _{L in} step 104, it is considered that the humidity inside and outside the vehicle is high and the window glass is likely to be fogged. Therefore, it is necessary to prevent the fogging of the window glass, and it is necessary to set the air conditioner to the above-mentioned window glass fogging prevention control.

In this case, in step 105, the compressor on / off set temperature is set to a small value T _L. T _L is 2 ° C
It is the value before and after. As a result, the air temperature after the evaporator is maintained at _TL , the cooling capacity is increased, and the dew point of the air blown into the vehicle is lowered, so that the window glass can be prevented from fogging.

Next, at step 106, the opening degree of the air mix damper 31 is controlled so that the blowout temperature becomes the target blowout temperature T _ao , and the heater core 30 partially heats it to maintain the vehicle compartment temperature at the set temperature T _set . Next, step 108 RETUR
At N, the process returns to START in step 100, and thereafter the above operation is repeated.

FIG. 5 is an explanatory view when a part of the first embodiment is changed. That is, when the amount of solar radiation is equal to or less than the predetermined value S _L in step 104, an example is shown in which the compressor on / off set temperature is changed according to the amount of solar radiation instead of the constant value T _L. In FIG. 5, the amount of solar radiation is the predetermined value S _Lo.
If it is smaller, the compressor on / off set temperature is set to a constant value T _L , and if S _Lo is exceeded, the compressor on / off set temperature is increased from T _L to T _ao in proportion to the increase in the amount of solar radiation. The amount of solar radiation when the compressor on / off set temperature becomes T _ao is S _L. As a result, the vehicle interior temperature can be smoothly controlled, and the evaporator 3 can be controlled.
The excessive cooling by 2 and the excessive heating by the heater core 30 can be reduced, and power can be saved.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is the compressor 3 in FIG.
4 is a variable capacitance type.

In FIG. 6, step 200 is performed when the power is turned on.
The input values of the various sensors described above are read in step 201, and in step 202 the target outlet temperature T _ao for making the vehicle interior temperature the set temperature is calculated by the equation (1).

In step 203, it is determined whether the wiper is in operation or not. If it is not operating, the window glass is not easily fogged as described in the first embodiment, so that the air conditioner can be put into the power saving control.

Therefore, in step 204, the target outlet temperature T
comparing the _ao and the outside air temperature T _o, the lower the better the outside air temperature T _o, the air mix so that the actual air temperature turns off the compressor does not have to be cooled in the compressor 34 becomes equal to the target outlet air temperature T _ao The opening degree of the damper 31 is adjusted.
In this case, the compressor can be turned off, which saves power.

If the target outlet temperature T _ao is lower than the outside air temperature T _{o in} step 204, it is necessary to cool it by the compressor 34. Therefore, in step 207, the compressor 34 is turned on, and in step 208 the required compressor capacity for the current environmental conditions is set. Calculate and control. Details of step 208 will be described later.

Next, at step 209, the air mix damper 31 is fully closed. This is done in step 208
This is because the compressor capacity is controlled so that heating by the heater core 30 becomes unnecessary.

When the wiper is operating in step 203, it is determined in step 210 whether the amount of solar radiation detected by the solar radiation sensor 42 is larger than a predetermined value S _L.

When the amount of solar radiation detected by the solar radiation sensor 42 is larger than the predetermined value S _{L, the} window glass is less likely to be fogged, so the routine proceeds to step 204, where the same power saving control as that described above is performed.

If the amount of solar radiation is less than S _{L in} step 203, the humidity inside and outside the vehicle is high as described in the first embodiment,
Since it is considered that the window glass is easily fogged, the fogging prevention control of the window glass is performed.

That is, the compressor 34 is turned on in step 211, and the capacity of the compressor 34 is increased in step 212 to increase the cooling capacity. Here, as an example, a method of maximizing the compressor capacity to prevent the fogging of the window glass is shown. Of course, the capacity may be controlled so that the air temperature after the evaporator has a constant value (for example, around 2 ° C.).

In step 213, the temperature inside the vehicle is set to the set temperature T.
_In order to control to _set , the air mix damper 31 is _adjusted so that the actual blown air temperature into the passenger compartment becomes the target blown temperature T _ao.
Adjust the opening of to adjust the amount of heating by the heater.

Next, at RETURN at step 214, the process returns to START at step 200 and the above operation is repeated.

Next, the calculation / control of the compressor required capacity in step 208 will be described with reference to FIG.

In order to _{set the} vehicle interior temperature to the set temperature T _set without heating with the heater core 30, the compressor capacity may be controlled so that the temperature of the air passing through the evaporator 32 becomes the target outlet temperature T _ao .

Therefore, in step 301, the temperature T _eset of the refrigerant in the evaporator 32 for setting the air temperature after the evaporator to T _ao is _calculated by the equation (2).

[0077]

## _EQU2 ## T _eset = T _{ao −Δt} (2) Here, Δt may be a constant value or a value obtained by the equations (3) and (4).

[0078]

## EQU3 ## Δt = k _v V ^b (3) Δt = k _t V ^d (T _r −T _ao ) (4) where T _r is the vehicle interior temperature, V is the air volume passing through the evaporator 32, and k is _v , b, k _t , and d are constants.

Which of these may be used may be determined according to the required accuracy.

On the other hand, there is a predetermined relationship between the refrigerant temperature T _eset and the refrigerant pressure P _eset in the evaporator 32. That is, it is a generally known relationship between pressure and evaporation temperature,
In step 302, the refrigerant pressure _Peset is _obtained from the refrigerant temperature _Teset by the equation (5).

[0081]

## _EQU4 ## P _eset = F (T _eset ) (5) where F (T _eset ) is a function of T _eset .

Therefore, by setting the refrigerant pressure in the evaporator 32 to _Peset , the actual blowout temperature can be made the target blowout temperature T _ao .

At step 303, the refrigerant enthalpy i ₄ at the evaporator inlet is obtained.

This is the pressure-enthalpy diagram (P-
This is the enthalpy at point IV in the i-line diagram), which is the same as the enthalpy at point III in the figure. The enthalpy i ₃ at III is III
Determined based on the 'enthalpy i ₃ points' but, III 'enthalpy i ₃ points' is calculated by equation (6) from the relationship between enthalpy and pressure of saturated liquid refrigerant.

[0085]

I ₃ ′ = f _L (Pc) (6) where Pc is the capacitor pressure detected by the capacitor pressure sensor 51 (FIG. 1). Further, f _L (Pc) is a function of Pc.

The enthalpy i _{3 at the} point III is obtained from the equation (7) by this i ₃ ′.

[0087]

[Equation 6] i ₃ = i ₃ ′ −C _L · Δtc (7) Here, C _L is the specific heat of the refrigerant liquid, and Δtc is constant (for example, 5 ° C.).

Therefore, from i ₄ = i ₃ ,

Equation 7] _{i 4 = i 3 '-C} L · Δtc ... (8) thereby the refrigerant enthalpy i ₄ of the evaporator inlet is obtained.

Next, at step 304, point I in FIG. 8, that is, the enthalpy i ₁ of the refrigerant at the evaporator outlet is determined.

If the enthalpy at point I is i _{1 and} the enthalpy at point I ′ is i ₁ ′,

[Equation 8] i ₁ = i ₁ ′ + C _p · Δte (9)

Although Δte may be obtained by using a sensor,
Even if Δte is constant (for example, 10 ° C.), there is no problem so much. C _p is the constant pressure specific heat of the superheated refrigerant vapor.

I ₁ ′ is obtained from the equation (10), which is the relationship between the enthalpy of saturated vapor line and the pressure, as follows.

[0093]

I _{1 ′} f _v (P _eset ) (10) where f _v (P _eset ) is a function of P _eset .

Therefore, the enthalpy i _{1 at} point I is

(10) i ₁ = f _v (P _eset ) + C _p · Δt (11)

Next, the required cooling capacity on the air side in the evaporator 32 is calculated. Since the calculation differs depending on the intake of outside air, the intake of air inside the vehicle (inside air), and the mixing of inside and outside air, it is calculated separately. .

First, at step 305, it is determined whether the air intake is the outside air intake.

If the outside air is taken in, at step 313, the enthalpy i _F of the outside air is calculated by the equation (12).

[0098]

I _F = C _pa · T _o + (C _wv · T _o + L) X _o (12) where C _pa is the constant pressure specific heat of air, C _wv is the constant pressure specific heat of water vapor, and L is the evaporation of water. latent heat, T _o is the ambient temperature of the outside air temperature sensor 43 has detected. Further, X _o is the absolute humidity of the outside air, and here the relative humidity is kept constant and the absolute humidity at that time is used.

Next, at step 314, the above-mentioned i is added to the enthalpy i _s of the evaporator inlet air required for the subsequent calculation.
Substitute _F.

At step 315, the air volume of the air (outside air) after passing through the evaporator 32 is obtained.

In general, in controlling an air conditioner, the voltage applied to the electric motor 12 for driving the fan 11 is often uniquely determined by T _ao . The characteristics are as shown in FIG. 9, for example.

Also in this embodiment, the voltage with respect to the target outlet temperature T _ao is obtained from the relationship shown in FIG. 9, and this voltage is set as the voltage applied to the electric motor 12.

When the voltage is determined according to FIG. 9, the air volume corresponding to the applied voltage in FIG.
The amount of air blown by 1 is determined.

Therefore, in step 315, the air volume of the outside air is obtained from the outside air diagram V _F of FIGS. 9 and 10.

On the other hand, when it is judged in step 305 that the outside air is not taken in, it is judged in step 306 whether the inside air is taken in or not.

If the inside air is taken in, in step 310, the enthalpy i _R of the inside air is calculated by the equation (13).

I _R = C _pa · T _r + (C _wv · T _r + L) X _r (13) T _r is the vehicle interior temperature detected by the vehicle interior temperature sensor 44, X
_r is the absolute temperature of the inside air, where the relative humidity is kept constant and the absolute humidity at that time is used.

In this case, it is i _R that is substituted as the enthalpy i _s of the evaporator inlet air in step 311.

[0108] Thereafter, in step 312, similarly to step 315 described above, it obtains the internal air of the air volume by shy diagram V _R in FIGS.

Further, when it is determined in step 306 that the inside air is not taken in, the inside / outside air mixing enthalpy i _{F & R} is calculated by the equation (14) in step 307.

[0110]

Equation 13] _{i F & R = i R ×} r m / 100 + i F × (100-r m) / 100 ... (14) where r _m is the mixing ratio of the inside air (%).

In this case, it is the above i _{F & R} that is substituted as the enthalpy i _s of the evaporator inlet air in step 308.

Further, in step 309, FIG. 9 and FIG.
The inside / outside air mixed airflow is obtained by the inside / outside air mixing diagram V _{F & R} of 0.

The refrigerant discharge amount G is calculated in step 316 in any of the above three cases, that is, in the case where the air intake is outside air intake, inside air intake, and inside / outside air mixing.

First, the enthalpy i _ao of the evaporator outlet air (air having the target blowout temperature T _ao ) is obtained by the equation (15).

[0115]

I _ao = C _pa · T _ao + (C _wv · t _ao + L) X _ea (15) Here, X _ea is the absolute humidity of the air after passing through the evaporator 32, and is calculated as follows. .

That is, the absolute humidity whose dew point is t _ao is X.
If you say _D , this is

(15) X _D = G ₁ (T _ao ) ... (16) This is uniquely determined. G ₁ (T _ao ) is a function of T _ao .

The absolute humidity of the intake air from the air intake is X
_{If s} ,

If X _s −X _D ≧ 0, X _ea = X _D X _s −X _D <0, X _ea = X _s Thus, the absolute humidity X _ea of the air after passing through the evaporator 32 is obtained. . Here, X _s is X _s = X _o when the intake air is the outside air, X _s = X _r when the inside air is the inside air, and X _s = X _r when the intake air is the inside air.

X _{F & R} = X _r × r _m / 100 + X _o (100
−r _m ) / 100.

Letting V be the air flow rate obtained in each of step 309, step 312, and step 315, the enthalpy of the evaporator inlet air is i _s, so the required cooling capacity on the air side is

[Expression 18] (i _s −i _ao ) × γV (17)

Here, i _s is i _F , i _{R of} the equations (12) to (14) depending on whether the intake air is the outside air, the inside air, or the inside / outside air mixture,
i _{F & R} (step 308, step 311, step 314).

Γ is the specific weight of air. The air volume V is the air volume blown by the fan 11 as described above, and is V _{F in} the case of outside air and V _F in the case of inside air as shown in FIG.
_{If R 2} and inside / outside air are mixed, V _{F & R} is obtained (step 309, step 312, step 315).

On the other hand, with respect to the required cooling capacity on the air side thus obtained, the cooling capacity on the refrigerant side is calculated by the following equation from the refrigerant discharge amount (refrigerant flow rate) G.

[0122]

## EQU19 ## G (i ₁ −i ₄ ) Here, i ₁ and i ₄ are obtained by the above equations (11) and (8).

The cooling capacity on the refrigerant side is equal to the required cooling capacity on the air side.

Therefore,

Equation 20] _{G (i 1 -i 4) =} (i s -i ao) × γV , and the refrigerant discharge amount G can be determined as follows.

[0125]

G = (i _s −i _ao ) × γV / (i ₁ −i ₄ ) ... (18) With the above, step 316 is completed.

Next, at step 317, the volume V _{cc of the} compressor 34 is determined so that the actual refrigerant discharge amount of the compressor becomes the refrigerant discharge amount G obtained by the equation (18). This volume _Vcc is _calculated by the following equation.

[0127]

V _cc = vG / (η _{vn c} ) ... (19) where η _v is the volumetric efficiency of the compressor 34 and can be obtained in advance.

N _c is the rotation speed of the compressor 34 detected by the rotation sensor 53 (FIG. 1). It may be calculated from the engine speed by the engine rotation sensor.

V is the specific volume of the refrigerant gas at the compressor inlet, and is calculated as follows.

[0130]

V = R · T _s / P _eset (20) R is the gas constant of the refrigerant, T _s is the absolute temperature of the refrigerant at the compressor inlet (evaporator outlet), and P _eset = (Equation 5)
From F ( _teset )

## _EQU23 ## T _eset = F ^-1 (P _eset ) T _s = 273 + t _eset + Δte (21) Δte is the above-mentioned constant value (10 ° C.), and F ⁻¹ (x) is an inverse function of F (x).

In actual control, the feedback term and the error term when the control deviates from the target are added to the equation (19).

[0132]

[ _Equation 25] V _cc = v · G / (η _v · n _c ) −K (P _eset −P _e ) + C (22) where P _e is the evaporator refrigerant detected by the evaporator pressure sensor 52 (FIG. 1). The pressure, C is an error term, and K is a constant.

Although the condenser pressure sensor 51 and the evaporator pressure sensor 52 are used here, a condenser temperature sensor and an evaporator temperature sensor may be provided instead. This is because, in this case, the pressure and the evaporation (condensation) temperature are uniquely determined in the condenser 33 and the evaporator 32 and can be mutually converted as in the following equation.

[0134]

P _c = F (tc), P _e = F (te) tc = F ⁻¹ (P _c ), te = F ⁻¹ (P _e ) In step 318, the control device 40 controls the compressor 34 A control signal is output to the variable capacity mechanism of the compressor 34 to control the compressor capacity so that the capacity becomes the volume obtained by the equation (22).

Finally, at RETURN in step 319, the process returns to step 300 and the above operation is repeated.

In addition, the cooling capacity can be controlled to be increased or decreased by rotating the compressor with an electric motor instead of using the engine as a power source instead of using a variable displacement compressor.

[0137]

As described above, according to the present invention,
When the wiper is operating and the amount of solar radiation is less than the predetermined amount, the window glass is apt to fog and the cooling capacity is increased.However, even if the wiper is not operating or the wiper is operating, If the amount is equal to or more than the predetermined value, the window glass is less likely to be fogged, so the cooling capacity is not increased and the same control as that when the wiper is not operated is performed.

As a result, it is possible to achieve both power saving and the prevention of fogging of the window glass without using an expensive humidity sensor.
It is possible to provide a vehicle air conditioner that can reduce the chances of switching the compressor on and off and reduce the deterioration of the riding comfort of passengers.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a vehicle air conditioner of the present invention.

FIG. 2 is a block diagram showing a configuration of the present invention.

FIG. 3 is a flowchart of the operation concept of the present invention.

FIG. 4 is a flowchart of the first embodiment.

FIG. 5 is an explanatory diagram when a part of the first embodiment is changed.

FIG. 6 is a flowchart of a second embodiment.

7 is a detailed flowchart of a compressor required capacity calculation control part of FIG.

FIG. 8 is a P-i diagram of a refrigerant.

FIG. 9 is a diagram showing a relationship between a target outlet temperature T _ao and an applied voltage.

FIG. 10 is a diagram showing a relationship between an applied voltage and an air volume.

[Explanation of symbols]

 10 Ventilation Duct 11 Fan 12 Electric Motor 13, 14 Inside / Outside Air Switching Damper 15, 16 Actuator 17, 18 Switching Damper 21, 22 Vehicle Interior Air Intake 23, 24 Outside Air Intake 25 Vent Outlet 26 Heater Outlet 27 Defroster Outlet 30 Heater core 31 Air mix damper 32 Evaporator 33 Condenser 34 Compressor 35 Expansion valve 36 Fan speed control device 37 Air mix damper actuator 40 Control device 41 Wiper switch 42 Solar radiation sensor 43 Outside air temperature sensor 44 Vehicle interior temperature sensor 45 Air temperature sensor after evaporator 46 46 Temperature Setting device 51 Condenser pressure sensor (temperature sensor) 52 Evaporator pressure sensor (temperature sensor) 53 Rotation sensor

Claims (1)

[Claims] 1. A cooling capacity control means for controlling a cooling capacity of a cooling heat exchanger for cooling air for air conditioning, a wiper operation detecting means for detecting an operation of a wiper, and an insolation amount detecting for detecting an insolation amount. Means, and the cooling capacity control means reduces the cooling capacity to perform power saving control based on the detection results of the wiper actuation detection means and the solar radiation amount detection means, or increases the cooling capacity to prevent fogging of the window glass. When the wiper is activated and the amount of insolation is less than or equal to a predetermined amount, the cooling capacity control means increases the cooling capacity of the cooling heat exchanger to mist the window glass. A vehicle air conditioner characterized by performing prevention control, and otherwise reducing cooling capacity to perform power saving control.