JP3298151B2 - Vehicle air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a vehicle, and more particularly to an air conditioner for controlling the temperature of a passenger compartment by controlling the temperature of blown air using cooling means and heating means.

[0002]

2. Description of the Related Art An air conditioner for a vehicle takes in air inside and / or outside of a room, adjusts the temperature and humidity of the air taken in by a cooler or a heater, blows the air into the vehicle interior, and sends the air to the vehicle. It controls room temperature and humidity. The above-described cooler utilizes a so-called cooling cycle utilizing the heat of vaporization of the refrigerant gas. Conventionally, a compressor used in this cooling cycle has a constant discharge capacity. If such a compressor with a fixed discharge capacity is used for an air conditioner for a vehicle, the cooling capacity cannot be adjusted, and the compressor cools to the maximum at full load, while once cooled air is required by the heater. The temperature is controlled by heating to a suitable temperature, or the indoor temperature is controlled by turning the compressor on and off, which is a cycle of full load and no load.

In the former case, the power of the compressor is increased more than necessary by wastefully using energy for cooling and heating more than necessary. In the latter case, the compressor
Due to the repeated turning off, the room temperature repeatedly rises and falls around the set temperature, giving the occupant a feeling of discomfort.

In order to solve this problem, a variable displacement compressor capable of changing the discharge capacity has been developed, and an air conditioner using the compressor has been developed in Japanese Patent Publication No. 1-33644.
No. in the official gazette. In this air conditioner, the capacity of the compressor is adjusted by changing the capacity of the compressor in accordance with the target temperature, which is the temperature of the blown air required to bring the cabin temperature to the set value, and the heating is also performed. The heating capacity of the vessel is also adjusted to control the desired temperature. That is, when the target temperature is low, the capacity of the cooler is increased, and as the target temperature increases, the capacity of the cooler is reduced, and the capacity of the heater is increased to perform temperature control.

[0005]

However, in the technology disclosed in the above publication, when the temperature is low, the capacity of the cooler is controlled to be low, the refrigerant temperature becomes high, and the dehumidifying action is reduced. When the temperature is low and the humidity is high, the dehumidifying effect is reduced as described above, so that the humidity in the vehicle compartment does not decrease and there is a possibility that dew may condense on the window glass. Such a state where the temperature is low and the humidity is high tends to occur in rainy weather. In the rainy weather, windows are often closed in order to prevent raindrops from being blown, which also causes an increase in vehicle interior humidity.

As described above, according to the conventional apparatus, when the required cooling capacity is low and the required dehumidifying action is high, such as during rainy weather, sufficient dehumidification is not performed and the window glass may become fogged. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to maintain a sufficient dehumidifying effect not only when the occupant discomfort is solved but also when the required cooling capacity is low such as in rainy weather. In addition, it is intended to save energy by preventing the window glass from fogging and suppressing unnecessary cooling.

[0008]

In order to achieve the above object, an air conditioner for a vehicle according to the present invention comprises a heating means capable of controlling a heating capacity, a cooling means capable of controlling a cooling capacity, and an outside air. Based on information from at least one of a temperature sensor, a vehicle interior temperature sensor, and a solar radiation sensor,
A target temperature calculating means for calculating a target value of the blow-off air temperature to control the vehicle interior temperature to a preset temperature, and a glass surface for estimating a window glass temperature from the outside air temperature sensor and the vehicle interior temperature sensor Temperature calculation means, calculates the required humidity of the blown air based on the humidity with the estimated glass surface temperature as the dew point, and the required blown air temperature calculation means to calculate the dew point temperature of the air with the calculated humidity; and Comparing the target temperature and the required temperature of the blown air,
Control temperature calculating means for setting a lower temperature as a control temperature, cooling control means for controlling the cooling capacity based on the control temperature, and heating control for controlling the heating capacity based on the control temperature and the target temperature. Means and have.

[0009]

In the air conditioner for a vehicle according to the present invention, the surface temperature of the window glass is estimated by various sensors, and the humidity of the blown air is calculated so that the inside of the vehicle becomes non-condensing at the glass surface temperature. The dew point temperature in the air indicating the calculated humidity is calculated. Control the cooler using the lower of the target temperature of the blow-off air required to control the vehicle interior temperature to the set temperature and the above-mentioned dew point temperature as the control temperature of the cooler, and cool to a lower temperature. There is no.

The above-mentioned dew point temperature is, in other words, the upper limit of the target temperature for obtaining a dehumidifying capacity that does not cause fogging of the window glass. When the cooler is operated at a target temperature exceeding this, a sufficient dehumidifying capacity is obtained. I can't. For example, if the target temperature of the blown air is equal to or higher than the above dew point temperature, the absolute humidity at the time of saturation of this air is higher than the absolute humidity of the air at the dew point temperature, and therefore, the vehicle controlled by the blown air under each of these conditions. When the room humidity is controlled at a target temperature higher than the dew point temperature, the room humidity becomes higher, and the window glass surface exceeds the saturation amount. Since the blown air is not always close to the saturated steam pressure, even if control is performed based on the target temperature equal to or higher than the dew point temperature, the window glass is not always fogged, but it is controlled at least at the target temperature equal to or lower than the dew point temperature. If condensation does not occur. Moreover, the compressor operates at less than full load.

Under the condition that the window glass can be fogged, the window glass is cooled to the calculated value of the dew point temperature of the blown air calculated from the calculated glass surface temperature to prevent the fogging of the window. Does not cool down to the full load of
Reduce the load on the compressor. In this case, the cooled air can be partially heated by a heater to bring the room temperature to the set temperature. Thereby, the window glass does not fog and energy saving can be achieved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the vehicle air conditioner of the present embodiment. This embodiment is an example particularly used for an automobile that is powered by an internal combustion engine, and a heater using cooling water of the internal combustion engine as a heating unit, and a variable displacement compressor driven by the engine as a cooling unit. 2. Description of the Related Art Coolers that perform a refrigeration cycle by compressing a refrigerant and expanding and vaporizing the refrigerant are used.

The vehicle air conditioner of this embodiment has a ventilation duct 10, a fan 11, an electric motor 12, internal / external air switching dampers 13, 14, and actuators 15, 16.
Air outlet switching dampers 17, 18, interior air intakes 21, 22, outside air intakes 23, 24, vent air outlet 25, heater air outlet 26, defroster air outlet 27, heater core 30. , Air mix damper 31
, An evaporator 32, a condenser 33, a variable capacity compressor 34, an expansion valve 35,
Fan speed control device 36, air mix damper actuator 37, control device 40, outside air temperature sensor 4
1, a vehicle interior temperature sensor 42, a solar radiation sensor 43, a condenser pressure sensor 45, and an evaporator pressure sensor 46.
, Compressor suction temperature sensor 47 and rotation sensor 4
8 and a temperature setting device 49.

Next, the operation will be described. In the vehicle air conditioner configured as described above, the ventilation duct 10
Has air inlets 21, 22, 23, 24 at one end,
Immediately after the air intakes 21, 22, 23, and 24, the fan 11 is disposed, and the air outlets 25 and 2 at the other end.
It is blowing towards 6,27. Fan 11 is electric motor 1
The rotation speed of the electric motor 12 is controlled by a fan speed control device 36 which receives a command from the control device 40. In this case, the fan speed control device 36 may be constituted by a transistor, in which case the fan speed is duty controlled.

The air intakes 21, 22, 23, 24
Is a vehicle interior air intake 21 for taking in the air in the vehicle interior,
22 and outside air intakes 23 and 24 for taking in outside air, and the air intakes 21 and 22 and 23 and 24 are switched by the inside / outside air switching dampers 13 and 14 to thereby take in air in the vehicle interior or take in outside air. Can be turned on. In addition, air intakes 21, 22, 23, 2
4, the inside / outside air switching damper 13 opens the air intake 21, closes the air intake 23, and the inside / outside air switching damper 14 opens the air intake 24, and closes the air intake 22, so that the inside air and outside air of the vehicle interior are closed. You can incorporate both. 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. An evaporator 32, which is a heat exchanger for cooling, is arranged over the entire cross section of the ventilation duct 10 downstream of the fan 11, and cools the passed air.
Further, a heater core 30 as a heat exchanger for heating is provided downstream.
Occupies a part of the cross section of the ventilation duct 10, and one end of the heater core 30 is provided with an air mix damper 31.
By changing the rotation angle of the air mix damper 31, the ratio of the air passing through the heater core 30 and the air bypassing the heater core 30 can be changed from 0 to 100% by changing the rotation angle of the air mix damper 31. The current angle with respect to the maximum rotation angle of the air mix damper 31 is referred to as the opening degree of the air mix damper 31 (when the heater core 30 is fully closed, the opening degree is 0). The outlet air temperature can also be changed by changing the opening degree.
The air mix damper 31 is operated by an air mix damper actuator 37 based on a command from the control device 40.

Further downstream therefrom is a vent outlet 25.
, A heater outlet 26, and a defroster outlet 27, the vent outlet 25 blows out mainly toward the upper body of the occupant, and the heater outlet 26 blows out mainly toward the foot of the occupant. 27 blows out toward the front window. Vent outlet 25 and defroster outlet 2
7 is switched by the switching damper 17, and the heater outlet 26 is switched by the switching damper 18. Then, the evaporator 32, the condenser 33,
A refrigerating cycle is constituted by the compressor 34 and the expansion valve 35. The compressor 3
4 is a variable capacity compressor.

That is, a wobble plate may be provided on the drive shaft, and the discharge amount may be controlled by changing the piston stroke by freely changing the inclination angle of the wobble plate. Of course, another structure may be used.

Next, the controller 40 controls the outside air temperature sensor 4
1, the vehicle interior temperature Tr detected by the vehicle interior temperature sensor 42, the solar radiation amount ST detected by the solar radiation sensor 43, and the set temperature Tse from the temperature setting device 49.
t is input, and a target blow-out air temperature Tao required for setting the vehicle interior temperature to the set temperature Tset is obtained from the information by using equation (1).

Tao = k1, Tset-k2, Tr-k3, To-k4, ST + c1 (1) Here, Tset... Set temperature from the temperature setting device 49 Tr. ... Detected by the outside air temperature sensor 41... The outside air temperature ST detected by the outside air temperature sensor 41. The solar radiation amounts k1, k2, k3, k4, and c1 detected by the solar radiation sensor 43 are constants.

Next, the glass surface temperature Tg of the window glass is calculated by the equation (2).

Tg = k 5 · To + k 6 · Tr + k 7 · ST (2) k 5, k 6, and k 7 are constants or fogging of the window glass becomes a problem when sunlight is weak such as in rainy weather. ').

Tg = k 5 ′ · To + k 6 ′ · Tr (2 ′) k 5 ′ and k 6 ′ are constants Note that each constant depends on the difference in the capacity of the vehicle compartment, the arrangement of the outlets, the capacity of the cooler and the heater, and the like. It is desirable to set for each vehicle type. Further, it may be changed according to the vehicle speed or the wind speed of the blown air. That is, it may be changed as a function of the vehicle speed or the wind speed of the blown air.

The absolute humidity Xg with the calculated glass surface temperature Tg as the dew point is determined by equation (3). If the absolute humidity in the cabin is smaller than Xg, the glass surface does not fog, so that there is a margin and let Xg-ΔXg be the target humidity in the cabin. (Absolute humidity) Xao can be obtained by equation (4). Equation (4) is a calculation formula applied when a feedback is made based on the vehicle interior humidity by installing a vehicle interior humidity sensor. Humidity Xao is obtained by equation (5). Xg = F1 (Tg) (3) where F (x) is a function. Xao = kh1, Xrset-kh2 (Xr-Xrset) + c2 (4) where Xrset: target humidity in the vehicle interior Xr: vehicle humidity detected by the vehicle interior humidity sensor kh1, kh2, c2 Is a constant. Xao = kh1.Xrset + c3 (5) Here, kh1 and c3 are constants.

For calculating the target outlet air humidity Xao, either of the equations (4) and (5) may be used. However, if the equation (4) is used, the control accuracy is improved, but a vehicle interior humidity sensor is required. On the contrary, if the equation (5) is used, the control accuracy is deteriorated, but there is an advantage that the humidity sensor in the vehicle compartment becomes unnecessary.

Next, the dew point temperature Td of the air at the target outlet air humidity Xao obtained from the absolute humidity Xg is obtained by equation (6). Then, the dew point temperature Td and the target outlet air temperature Ta
Compare o and if the smaller one is the air after passing through the evaporator, the window will not fog. That is, assuming that the temperature of the air after passing through the evaporator is Tea, Tea is expressed by the equation (7).
We ask for it.

That is, if the cooler is operated so that the air temperature after passing through the evaporator is equal to or less than Tea, a sufficient dehumidifying ability can be obtained so that the target outlet humidity is set to Xao.
Therefore, the humidity in the room becomes equal to or lower than Xrset, and the glass does not fog.

Next, the air temperature after passing through the evaporator becomes T
The evaporator refrigerant temperature Ter to be ea is obtained by Expression (8). Then, the refrigerant pressure Pset of the evaporator at which the refrigerant temperature of the evaporator becomes Ter is obtained by Expression (9). This is the evaporator target refrigerant pressure Pse
t. In the equation (10), the function F2 (x) is obtained from the relationship between the refrigerant pressure and the evaporation temperature.

Td = g (Xao) (6) where g (x) is a function, and g (x) = F1 ⁻¹ (x). F1 ^-1 (x) is the inverse function. kh1, kh2, c2
Is a constant. If Tao ≧ Td, Tea = Td (7) If Tao <Td, Tea = Tao Ter = Tea−Δtea (8) where Δtea is a constant value. Peset = F2 (Ter) (9) Next, Pi of FIG. 2 showing the relationship between the refrigerant pressure and the enthalpy
The enthalpy i4 at point IV is determined from the diagram. Since the enthalpy i4 at point IV is equal to the enthalpy at point III, equation (10)
Is determined by

I 4 = FL (Pc) −C · ΔTc (10) Here, Pc ·· Capacitor pressure detected by the capacitor pressure sensor 45 FL · (x) ·· Relational expression between the enthalpy of the saturated liquid line and the pressure c · ······ Specific heat of refrigerant liquid ΔTc ··· Sub-cool, for example, 5 ° C (constant) Next, the enthalpy i1 of the compressor suction refrigerant (point I in the Pi diagram) is obtained by equation (11). . In the equation (11), the evaporator refrigerant temperature Ter is obtained from the equation (8). Alternatively, it may be obtained by equation (12).

I 1 = F V (Peset) + Cpr · Δter (11) where Δter = Te−Ter. Also, Te:... Compressor suction refrigerant temperature detected by compressor suction refrigerant temperature sensor FV (x): Relational expression between enthalpy and pressure of saturated vapor line Cpr: Constant heat of refrigerant at constant pressure Δter: Compressor Superheat degree of the suction refrigerant Ter = G2 (Peset) (12) Here, G2 (x) = F2 ^-1 (x). G2 (x)
Is a function, the relational expression F2 ^-1 (x) between refrigerant pressure and evaporation temperature.
Is the inverse function of F2 (x). Therefore, the cooling capacity viewed from the refrigerant side is represented by Expression (13). Qr = G (i1-i4) (13) Here, G is the refrigerant discharge amount.

On the other hand, the cooling capacity viewed from the air side is obtained as follows. In other words, first, the enthalpy of the intake air is determined.In this case, the enthalpy of the outside air is obtained when the air intake is the outside air intake, and the enthalpy of the vehicle interior air is obtained when the air intake is the inside of the vehicle, and when the air is mixed inside and outside. Is determined from the inside / outside air mixing ratio. Therefore, the enthalpy of the vehicle interior air can be obtained by equation (14), and the enthalpy of vehicle interior air can be obtained by equation (15). Equation (1
4), Xo (absolute humidity of outside air), Xr in (15)
(Absolute humidity in the vehicle interior) may be obtained by installing a humidity sensor inside or outside the vehicle interior, or assuming that the relative humidity inside and outside the vehicle interior is constant, for example, 50%, and the absolute humidity at that time is obtained. Is also good. The enthalpy for the case of mixing the inside and outside air is given by equation (16).
Ask by

If = Cpa · To + (Cwv · To + L) · Xo (14) ir = Cpa · Tr + (Cwv · Tr + L) · Xr (15) where L... Latent heat of vaporization of water Xo ······ Absolute humidity of outside air Xr ····· Absolute humidity of cabin Cpa ··· Specific heat of constant pressure of air Cwv ··· Specific heat of constant pressure of steam ifr = ir × Rm / 100 + if × (100−Rm) ) / 100 (16) where Rm is the mixing ratio of the air in the vehicle interior.

Next, the enthalpy iea of the air after passing through the evaporator is obtained by the equation (17). In Expression (17), the temperature Tea of the air after passing through the evaporator is obtained by Expression (18) as described above. In Expression (17), the absolute humidity Xea of the air after passing through the evaporator is obtained by Expression (19). In equation (19), the target outlet air temperature Ta
The absolute humidity Xd with o as the dew point is Xd = F1 (Tao)
The absolute humidity Xea of the air after passing through the evaporator is obtained by setting the absolute humidity of the intake air to Xs.

Iea = Cpa · Tear + (Cwv · Tea + L) · Xea (17) If Tao ≧ Td, Tea = Td (18) If Tao <Td, then Tea = Tao, and if Tao ≧ Td, Xea = Xao (19) In the case of Tao <Td, if Xs ≧ Xd, then Xea = Xd, if Xs <Xd, then Xea = Xs, where Xs is Xs = Xr if the air intake is the vehicle interior air intake, Xs = Xr if the external air intake is Xs = Xo if the internal / external air mixture Xs = (Xr × Rm) / 100 + {Xo × (100−Rm) / 100} Next, the air volume of the air conditioner, that is, the air volume passing through the evaporator is determined. In many cases, the air flow rate of the air conditioner uniquely determines the voltage applied to the blower motor based on the target blown air temperature Tao. As an example, the case of the first embodiment will be described. First, FIG. 3 shows the correspondence between the target outlet air temperature Tao and the applied voltage. FIG. 4 shows the correspondence between the applied voltage and the air volume of the air conditioner. Therefore, the value of the applied voltage with respect to the specific value of the target outlet air temperature Tao is determined from FIG. 3, and the value of the air volume of the air conditioner corresponding to the value of the applied voltage is determined from FIG. You decide.

Thus, the cooling capacity viewed from the air side is required. This is shown in equation (20). Since the cooling capacity as viewed from the air side is equal to the cooling capacity as viewed from the refrigerant side, Equation (21)
Holds, and equation (22) is derived from equation (21). Substituting equations (10) and (11) for i1 and i4 in equation (23),
Equation (23) is obtained. The variable displacement compressor capacity Vc can be obtained by the equation (24) based on the refrigerant discharge amount G obtained by the equation (23). In the equation (24), V11 is a specific volume when the refrigerant is sucked into the compressor, and can be obtained by the equation (25). Further, ηv in the equation (24) is a volume efficiency, and the equation (2)
6). In equation (26), n
c is the number of rotations of the compressor, which may be detected by adding a rotation sensor to the compressor, or may be obtained from the number of rotations of the engine.

(Is-iea) × V × Υa (20) where is is the enthalpy of the intake air is = ir for vehicle interior air, is = if for outside air, and is = ifr for mixed inside and outside air. . V: Air volume Vr for vehicle interior air, Vf for outside air, V for mixed indoor / outdoor air
fr. (See FIG. 4) {a ... specific air weight G (i1-i4) = (is-iea) * V * {a ... (21) G = {(is-iea) .V. {A} / (i1) −i4) (22) G = {(is-iea) · V · {a} / [FV (Peset) + Cp · Δte− {FL (Pc) −C · ΔTc}] (23) Vc = G / ( ηv × nc × v11) (24) V11 = R · Te / Peset (25) where R ·················································································································································································································· The detected refrigerant suction refrigerant temperature ηv = f1 (nc, Pc / Peset) (26) where f1 (x) is a function.

Next, in the equation (24) for obtaining the capacity Vc of the variable capacity compressor, a feedback term for the feedback when the compressor capacity control deviates from the target value and an error term considering the error are taken into account in the equation (24). (27)
To obtain the capacity Vc of the variable capacity compressor.

Vc = {G / (ηv × nc × v11)} − K (Peset−Pe) + C (27) where Pe... Evaporator refrigerant pressure detected by the evaporator pressure sensor 46. When the temperature Tea of the air after passing is equal to the target outlet air temperature Tao, that is, Tao <Td
, The compressor capacity is controlled by equation (24), the air mix damper 31 is fully closed, and the ventilation duct 1
All the air flowing through the heater core 30 is bypassed.

On the other hand, if Tea = Td, ie, Ta
When o ≧ Td, it is necessary to set the outlet air temperature to the target outlet air temperature Tao and set the vehicle interior temperature Tr to the vehicle interior set temperature. Therefore, it is necessary to control the opening of the air mix damper 31 to increase the blown air temperature to the target blown air temperature Tao. In this case, in order to set the blown air temperature to the target blown air temperature Tao, the mixing ratio Υam of the warm air heated by the heater core 30 by the air mix damper 31 and the cool air bypassing the heater core 30 is obtained by Expression (28). In Expression (28), Th may be detected by a sensor using the temperature of the air immediately after the heater core, or may be obtained from Expression (29) from the engine cooling water temperature. However, the cooling water temperature of the engine needs to be detected by a sensor.

Υam = (Tao−Td) / (Th−Td) (28) Here, the mixing ratio Υam is the ratio of warm air in the total air volume. Th = A · Tw + (1−A) Td (29) where Tw ···· Engine cooling water temperature A ······· Constant (0 ≦ A ≦ 1) The control device 40 controls the air mix damper 31 , Mixing ratioΥ
By controlling am so as to be a value as shown in Expression (28), the blown air temperature can be set to the target blown air temperature Tao.

In the above embodiment, the superheat degree ΔTe of the compressor suction refrigerant is obtained by using the refrigerant temperature detected by the compressor suction temperature sensor 47. However, the superheat degree of the compressor suction refrigerant is used without using the compressor suction temperature sensor 47. ΔTe may be set to a constant value, for example, 10 ° C. A temperature sensor may be used for the condenser pressure sensor and the evaporator pressure sensor. This is because the evaporation temperature and pressure of the refrigerant can be converted into each other.

The air temperature after passing through the evaporator is T
In the above-described embodiment, the evaporator refrigerant temperature Ter, which is ea, is obtained by the equation (8), but is obtained by the equation (30) or the equation (31).
You may ask for it.

Tea−Ter = Kv · V ^b (30) Tea−Ter = Kt · V ^d (Tr−Tao) (31) where Kv, b, Kt, and d are constants.

In the above embodiment, when the capacity of the variable capacity compressor 34 is set to Vc shown in the equation (27),
The piston stroke and the capacity of the compressor are in a proportional relationship, and a stroke for obtaining the capacity of Vc in Expression (27) can be easily obtained using a stroke sensor. Is controlled, the desired capacity can be obtained.

This will be described in more detail with reference to the flowcharts shown in FIGS. In the air conditioner for a vehicle according to the first embodiment of the present invention, the control device 40 reads inputs from various sensors such as an outside air temperature sensor 41, a vehicle interior temperature sensor 42, and a solar radiation sensor 43 (Step 101). next,
The control device 40 controls the outside air temperature To detected by various sensors,
From the vehicle interior temperature Tr, the amount of solar radiation ST, and the set temperature Tset, a target blow-off air temperature Tao required for setting the vehicle interior temperature to the set temperature is obtained by equation (1) (step 102).

Further, the temperature of the glass surface of the window is obtained from the outside air temperature To, the vehicle interior temperature Tr, and the amount of solar radiation ST by using equation (2) (step 103).

Next, the glass surface temperature Tg calculated by the equation (2)
The absolute humidity Xg with the dew point as the dew point is determined by equation (3) (step 104).

Next, a target humidity Xg-.DELTA.Xg in the vehicle compartment is calculated (step 105). Next, the target humidity X
The target outlet air humidity Xao for obtaining g−ΔXg is obtained by equation (4) (step 106). Next, the absolute humidity X
The dew point temperature Td of the air at the target outlet air humidity Xao obtained from g is obtained by equation (6) (step 107).

Next, the dew point temperature Td is compared with the target outlet air temperature Tao (step 108). As a result of the comparison, T
If ao is smaller than Td, the process moves to step 109. In step 109, the evaporator refrigerant temperature Ter is determined by the equation (8), where the temperature of the air after passing through the evaporator is Tea, and the refrigerant temperature of the evaporator becomes T.
The refrigerant pressure Pset of the evaporator as er is obtained by Expression (9).

Next, the enthalpy i4 of the refrigerant at the inlet of the evaporator is obtained by the equation (10) (step 110).
Next, the enthalpy i1 of the refrigerant at the outlet of the evaporator is obtained by equation (11) (step 111). Next, the enthalpy is of the intake air is obtained (step 112). Here, when the air intake is performed from the outside air, the enthalpy if of the vehicle outside air is obtained by Expression (14), and this if is substituted for is. On the other hand, when the air intake is performed from outside air, the enthalpy ir is obtained by the equation (15), and this ir is substituted for is. In addition, the enthalpy ifr in the case of the inside / outside air mixture is obtained by Expression (16).
Substitute fr for is.

Next, the enthalpy of the air after passing through the evaporator is obtained by the equation (17) (step 11).
3). Here, in this case, the temperature Tea of the air after passing through the evaporator is the target blowing air temperature Tao, and the enthalpy of the air after passing through the evaporator is the enthalpy of the air at the target blowing air temperature Tao. It can be obtained by equation (17). In this case, the absolute humidity Xea of the air after passing through the evaporator is obtained by Expression (19), and is expressed by Expression (1).
In 9), the absolute humidity Xd with the target outlet air temperature Tao as the dew point is obtained from Xd = F1 (Tao).

Next, the air volume of the air conditioner, that is, the air volume passing through the evaporator is obtained (step 114).
In this case, the target outlet air temperature Tao from FIG.
Of the air conditioner is determined by determining the value of the applied voltage with respect to the specific value of the air conditioner, and determining the value of the air flow of the air conditioner corresponding to the value of the applied voltage from FIG. Then, the cooling capacity viewed from the air side is obtained by equation (20) (step 115). Next, the refrigerant discharge amount G is obtained by Expression (23) (Step 116), and Expression (23) is obtained.
The variable displacement compressor capacity Vc is obtained from the refrigerant discharge amount G obtained by the above (step 117). Note that the variable capacity compressor capacity Vc can be obtained by the equation (27).

Next, the variable capacity compressor capacity Vc
Is output to the compressor variable displacement mechanism (step 11).
8).

Here, the case where the temperature Tea of the air after passing through the evaporator is equal to the target blown air temperature Tao, that is, the case where Tao <Td is satisfied, is performed by controlling the compressor capacity by the equation (27) to control the air mix damper 31. The air that is fully closed and flows through the ventilation duct 10 is caused to flow so as to bypass the heater core 30 (step 119).
On the other hand, if Tea = Td in the comparison of step 107, that is, if Tao ≧ Td, an evaporator target refrigerant pressure Pset is determined in which the temperature of the air after passing through the evaporator is the dew point temperature Td (step 120).
In this case, the dew point temperature Td is substituted for the temperature Tea of the air after passing through the evaporator (Tea = Td), and the calculation of Expression (9) is performed. That is, the temperature Te of the air after passing through the evaporator
The evaporator refrigerant temperature Ter at which a becomes the dew point temperature Td is determined by equation (8), and the evaporator refrigerant pressure Pset at which the evaporator refrigerant temperature is Ter is determined by equation (9).

Next, the enthalpy i4 of the refrigerant at the inlet of the evaporator is obtained by the equation (10) (step 121).
Next, the enthalpy i1 of the refrigerant at the outlet of the evaporator is obtained by equation (11) (step 122). Next, the enthalpy is of the intake air is obtained (step 123). At this time, if the intake of air is the intake of outside air, the enthalpy if of the outside air of the vehicle compartment is obtained by equation (14), and the obtained if is substituted for is. On the other hand, in the case of vehicle interior air, the enthalpy ir of the vehicle interior air is obtained by equation (15), and this ir is substituted for is. The enthalpy ifr in the case of the inside / outside air mixture is obtained by Expression (16), and this ifr is substituted for is.

Next, the enthalpy of the air after passing through the evaporator is obtained by the equation (17) (step 12).
4). In this case, the temperature Te of the air after passing through the evaporator
a is the dew point temperature Td, and the enthalpy of the air after passing through the evaporator is the enthalpy of the air having the dew point temperature Td. Therefore, the enthalpy of the air after passing through the evaporator can be obtained by (17). In this case, the absolute humidity Xe of the air after passing through the evaporator
a is determined by equation (19), and in this case, Ta
Since o ≧ Td, the absolute humidity of the air after passing through the evaporator Xea = Xao.

Next, the flow rate of the air conditioner, that is, the flow rate passing through the evaporator is determined (step 125). In this case, the value of the applied voltage with respect to the specific value of the target outlet air temperature Tao is determined from FIG. 3, and the value of the air volume of the air conditioner corresponding to the value of the applied voltage is determined from FIG. To determine. Here, when the air intake is the outside air intake, VF is obtained.
R is obtained, and in the case of the inside / outside air mixture, VF and R are obtained from FIG. Then, based on these, the cooling capacity viewed from the air side is obtained by equation (20) (step 126),
The refrigerant discharge amount G is obtained by equation (23) (step 12).
7). Then, the refrigerant discharge amount G obtained by the equation (23)
Thus, the variable capacity compressor capacity Vc is obtained (step 128). The variable capacity compressor capacity Vc
Can be obtained from Expression (27).

Next, the variable capacity compressor capacity Vc
Is output to the compressor variable displacement mechanism (step 12).
9) Here, next, when Tea = Td, ie, T
When ao ≧ Td, it is necessary to set the outlet air temperature to the target outlet air temperature Tao and set the vehicle interior temperature Tr to the vehicle interior set temperature. Therefore, it is necessary to control the opening of the air mix damper 31 to increase the blown air temperature to the target blown air temperature Tao. In this case, the air mix damper 31 is used to set the blown air temperature to the target blown air temperature Tao.
Hot air heated by the heater core 30 and the heater core 30
The mixing ratio 冷 am of the cool air that bypasses is calculated by equation (28) (step 130).

The control device 40 controls the air mix damper 31 so that the mixing ratio Υam becomes a value as shown in the equation (28) so that the blown air temperature becomes the target blown air temperature Tao. Yes (Step 13
1). Thereafter, the process proceeds to step 132, and step 100
Is repeated.

In the present embodiment, the cooling capacity of the compressor is changed by changing the capacity of the variable capacity compressor. However, the present invention is not limited to this, and an air mix damper such as the heater shown in the embodiment is used. It is also possible to change the capacity by changing the proportion of air passing through the evaporator, etc., or to separate the compressor and engine from each other and drive them separately by a motor, etc., and control the compressor speed to change the cooling capacity It is.

Further, the heating capacity of the heater can be changed by controlling the temperature of the hot water flowing through the heater core.

[0063]

As described above, according to the vehicle air conditioner of the present invention, the compressor is not turned on / off, so that the occupant's discomfort can be eliminated and the window glass can be fogged. Cooling the window to the calculated value of the dew point temperature of the blown air calculated from the glass surface temperature calculated below also prevents fogging of the window. Reduce the load on the machine.

Further, the temperature of the window glass surface is the temperature of the vehicle interior,
Since the estimation is calculated from the outside air temperature and the amount of solar radiation, there is no need to provide a new sensor, and the present invention can be implemented only by changing the software of the existing device.

[Brief description of the drawings]

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

FIG. 2 is a Pi diagram showing a relationship between refrigerant pressure and enthalpy.

FIG. 3 is a diagram showing a correspondence relationship between a target blown air temperature Tao and an applied voltage.

FIG. 4 is a diagram showing a correspondence relationship between an applied voltage and a flow rate of an air conditioner.

FIG. 5 is a flowchart showing control contents (first half) of the vehicle air conditioner of the present embodiment.

FIG. 6 is a flowchart showing control contents (second half) of the vehicle air conditioner of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ventilation duct 11 Fan 12 Electric motor 13 and 14 Inside / outside air switching damper 15,16 Actuator 17,18 Outlet switching damper 21,22 Car room air intake 23,24 Outside air intake 25 Vent outlet 26 Heater outlet 27 Defroster blowing Outlet 30 Heater core 31 Air mix damper 32 Evaporator 33 Capacitor 34 Variable capacity compressor 35 Expansion valve 36 Fan speed control device 37 Air mix damper actuator 40 Control device 41 Outside air temperature sensor 42 Vehicle interior temperature sensor 43 Solar sensor 45 Capacitor pressure sensor 46 Evaporator Pressure sensor 47 Compressor suction temperature sensor 48 Rotation sensor 49 Temperature setting device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60H 3/00 B60H 1/00 101

Claims (1)

(57) [Claims] 1. A heating means capable of controlling a heating capacity, a cooling means capable of controlling a cooling capacity, and preset based on information from at least one of an outside air temperature sensor, a vehicle interior temperature sensor, and a solar radiation sensor. Target temperature calculation means for calculating a target value of the blow-out air temperature to control the vehicle interior temperature to the set temperature, and a glass surface temperature calculation for estimating a window glass temperature from the outside air temperature sensor and the vehicle interior temperature sensor. Means, calculating the required humidity of the blowing air based on the humidity with the estimated glass surface temperature as the dew point, and calculating the required dew point temperature of the air with the calculated humidity, the required blowing air temperature calculating means, A control temperature calculating unit that compares a target temperature of the blown air with a required temperature and sets a lower temperature as a control temperature; and a control unit that controls the cooling capacity based on the control temperature. An air conditioner for a vehicle, comprising: a cooling control unit; and a heating control unit that controls the heating capacity based on the control temperature and the target temperature.