JP2623747B2 - Vehicle air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air conditioner having a refrigeration cycle used for a vehicle such as an automobile.

[Prior Art] Conventionally, as this type of air conditioner, for example, as shown in FIG. 6, a blower 32 is provided at an inlet side of an air flow passage 31, and an evaporator 33 for air cooling is provided downstream of the blower 32. In some cases, a heater 34 for heating air is provided downstream of the evaporator 33. The evaporator 33 constitutes a well-known refrigeration cycle by the compressor 35, the condenser 36, the expansion valve 37, and the like.
The air sent from 32 is cooled and passed downstream. The heater 34 circulates cooling water of an engine (not shown) to radiate a part of the heat, and heats the air sent from the evaporator 33 to pass the air downstream.

An air mix damper 38 is provided in the vicinity of the heater 34, and the air that has passed through the evaporator 33 is separated into air that passes through the heater 34 and air that does not pass through the damper 38. The mixture is mixed downstream of the heater 34 and sent to the vehicle interior. Further, by adjusting the opening and closing amount of the air mix damper 38, the temperature of the air sent into the vehicle compartment is adjusted.

Here, a thermistor 39 is provided on the downstream side of the evaporator 33, and based on the temperature detected by the thermistor 39, the compressor
The on-off control of the 35 clutch 35a and, in the case of a variable compressor, the amount of refrigerant taken in the compressor are controlled to adjust the cooling capacity of the refrigeration cycle, and the temperature of the air blown from the evaporator 33 is constantly frosted. We are trying to cool to the limit.

The air conditioner as described above is used to dehumidify the interior of a vehicle during the rainy season or autumn rain when cooling is hardly required, as well as during the summer, as well as during the summer. That is, when the humidity is high, on a hot and humid day, or when the window glass in the passenger compartment becomes cloudy, by operating the air conditioner, the air is cooled and dehumidified by the evaporator 33 and heated to an appropriate temperature by the heater 34. Air is blown into the passenger compartment. As a result, refreshing air with low humidity is blown into the vehicle interior, and fogging of the window glass is also prevented.

[Problems to be Solved by the Invention] However, in the conventional air conditioner, the temperature of the air blown out from the evaporator 33 is always cooled to the frost limit, so that the air is cooled more than necessary during the rainy season or autumn rain. Will be done. That is, the air is cooled more than necessary in spite of the small heat load state of the vehicle, that is, the small cooling load in the passenger compartment, which causes a loss in the power of the refrigeration cycle.

Further, in order to solve the power loss described above, for example, a control method of increasing the setting of the blown air temperature of the evaporator 33 in response to a reduction in the thermal load state of the vehicle has been put to practical use.

However, in this control method, when the setting of the temperature of the air blown out of the evaporator 33 is increased, the temperature of the air blown out of the evaporator 33 approaches the outside air temperature, and the dehumidifying effect almost disappears,
In addition, since the compressor 35 does not operate and the dehumidifying effect is lost because the temperature becomes higher than the outside air temperature, fogging occurs on the window glass and the like, particularly in the spring, autumn, and winter, which is a problem.

The present invention has been made in view of the above-described circumstances, and an object thereof is to perform cooling and dehumidification in response to fluctuations in the thermal load state of a vehicle and to suppress fogging of a window glass. It is an object of the present invention to provide an air conditioner for a vehicle that is capable of reducing power loss for the vehicle.

Means for Solving the Problems In order to achieve the above object, the present invention provides a vehicle air conditioner provided with a refrigeration cycle having a compressor, a condenser, a pressure reducing means, and an evaporator. A suction refrigerant amount changing means for changing the suction refrigerant amount of the compressor to change the air cooling capacity of the evaporator; a heat load detection means for detecting a heat load state of the vehicle; and the heat load detection means. Calculating means for calculating the cooling load in the vehicle compartment based on the detected value; and when the cooling load calculated by the calculating means is greater than a first reference value, the air cooling capacity of the evaporator is reduced. A first control means for controlling the suction refrigerant amount changing means for adjusting to a relatively high first set value; and a cooling load calculated by the calculating means, wherein the cooling load calculated from the first reference value is lower than the same reference value. Up to a small predetermined second reference value A second control means for controlling the suction refrigerant amount changing means in order to adjust the air cooling capacity of the evaporator to a second set value lower than the first set value, and a calculating means. When the calculated cooling load is smaller than the second reference value, the third control for controlling the suction refrigerant amount changing means to adjust the air cooling capacity of the evaporator to a value higher than the second set value. Means.

[Operation] Therefore, the calculating means calculates the cooling load in the vehicle cabin based on the value detected by the heat load detecting means, and when the calculated cooling load is larger than a first reference value determined in advance, The first control means controls the suction refrigerant amount changing means to adjust the suction refrigerant amount of the compressor to a first set value. This increases the air cooling capacity of the evaporator.

When the cooling load calculated by the calculating means is in a range from the first reference value to a predetermined second reference value smaller than the first reference value, the second control means sets the suction of the compressor. In order to adjust the refrigerant amount to a second set value lower than the first set value, the controller controls the intake refrigerant amount changing means. by this,
The air cooling capacity in the evaporator is reduced.

Further, when the cooling load calculated by the calculating means is smaller than the second reference value, the third control means adjusts the refrigerant suction amount of the compressor to a value higher than the second set value. Control means for changing the amount of intake refrigerant. This increases the air cooling capacity of the evaporator.

Hereinafter, an embodiment in which the present invention is embodied in an air conditioner for a vehicle will be described in detail with reference to the drawings.

As shown in FIG. 1, a blower 2 is provided on the inlet side of the air flow passage 1, and an evaporator 3 for cooling air is provided on the downstream side of the blower 2, and further on the downstream side of the evaporator 3. Is provided with a heater 4 for heating air.

The evaporator 3 forms a well-known refrigeration cycle with the compressor 5, the condenser 6, the receiver 7, and the expansion valve 8 as a pressure reducing means, and cools the air sent from the blower 2 and passes it to the downstream side. .

In this embodiment, the compressor 5 is of a well-known variable displacement type, and performs variable displacement operation from a small displacement to a large displacement based on the operation of the solenoid valve 5a. The variable displacement compressor 5 itself constitutes a suction refrigerant amount changing means for changing the suction refrigerant amount. By changing the suction refrigerant amount in the compressor 5, the air cooling capacity in the evaporator 3 is changed. You.

Further, in this embodiment, a refrigerant pressure sensor 21 is provided in the middle of the refrigeration cycle between the evaporator 3 and the compressor 5. The refrigerant pressure sensor 21 detects the actual refrigerant pressure PE at the outlet of the evaporator 3 as a value corresponding to the blown air temperature of the evaporator 3 or the evaporation temperature.

The heater 4 circulates the cooling water of the engine 9 to radiate a part of the heat, and heats the air sent from the evaporator 3 to pass it downstream.

On the upstream side of the blower 2, an inside / outside air switching damper 10 for switching the introduction of inside air / outside air is provided. The inside / outside air switching damper 10 is switched and rotated based on the operation of the first servomotor 11.

Further, on the downstream side of the evaporator 3 and near the heater 4,
An air mix damper 12 is provided. Then, the air that has passed through the evaporator 3 is divided into air that passes through the heater 4 and air that does not pass through the air mix damper 12. The air is blown into the vehicle interior 14 from the outlet 1a at the temperature. The opening and closing of the air mix damper 12 is adjusted based on the operation of the second servomotor 13, and the opening and closing adjustment of the air mix damper 12 adjusts the temperature of air blown into the vehicle interior 14.

Further, an outlet switching damper 15 is provided downstream of the heater 4. The outlet switching damper 15 is switched and rotated based on the operation of the third servomotor 16, and the position of the air blown into the vehicle interior 14 is switched by the switching and rotation.

In this embodiment, an interior air temperature sensor 22 for detecting a temperature (inside air temperature) Tr of the vehicle interior 14 is provided in the interior of the vehicle interior 14.
A solar radiation sensor 23 for detecting the amount of solar radiation Ts to is provided. Further, in this embodiment, an outside air temperature sensor 24 for detecting a temperature outside the vehicle (outside air temperature) Tam, a temperature setting switch 25 for setting a set temperature Tset of the vehicle interior 14, switching between inside and outside air, and a vehicle interior 14. A mode setting switch 26 is provided for instructing the switching of the air blowing position to the air and the change of the air blowing amount to the vehicle interior 14, respectively. The internal air temperature sensor 22, the solar radiation sensor 23 and the external air temperature sensor 24 constitute a heat load detecting means for detecting a heat load state of the vehicle.

ECU (Electronic Control Unit) 27 is an arithmetic means,
, The second control means, and the third control means, and have respective functions of calculation, storage, judgment, and timing. The ECU 27 executes calculations, determinations and controls based on a control program stored in advance.

Here, a series of control operations of the ECU 27 will be described with reference to the flowchart of FIG.

When the engine 9 is started and the compressor 5 is driven, in step 101, the actual refrigerant pressure PE and the inside air temperature T
In order to obtain data of r, the amount of solar radiation Ts, the outside air temperature Tam, and the set temperature Tset, a detection signal is input from each of the sensors 21 to 24 and a setting signal is input from the temperature setting switch 25.

Next, the process proceeds to step 102, where the data PE, Tr, Ts,
Based on Tam, Tset, required blowing temperature T corresponding to cooling load
A0 (the cooling load increases as the value decreases) is calculated. In this embodiment, the required blowing temperature TA0, which is an index of the magnitude of the cooling load, is calculated based on the following formula (1).

TA0 = 4.times.Tset-3.times.Tr -1.5.times.Tam-2.times.Ts + 30 (1) Then, the process proceeds to step 103, where the evaporation is performed based on the calculation result of the required blowing temperature TA0 as an index of the cooling load. The set refrigerant pressure PE0 at the outlet of the vessel 3 is determined. Here, the set refrigerant pressure PE0 corresponding to the required blowing temperature TA0 is determined based on the map shown in FIG. 2 stored in advance.

That is, when the required blowing temperature TA0 is lower than the upper limit of 0 ° C., the set refrigerant pressure PE0 is set to 1.85 kg / cm ^{2 in} order to increase the air cooling capacity in the evaporator 3, and the required blowing temperature TA0 is between 0 ° C. and 10 ° C. In the case of, the set refrigerant pressure PE0 is set to 1.85 to 3.0 k in order to gradually lower the air cooling capacity in the evaporator 3.
g / cm ² , and when the required blowing temperature TA0 is between 10 ° C. and 35 ° C., the set refrigerant pressure PE0 is set to 3.0 kg / cm ² to reduce the air cooling capacity in the evaporator 3. When TA0 is between 35 ° C. and the lower limit of 45 ° C., the set refrigerant pressure PE0 is changed between 3.0 and 1.85 kg / cm ^{2 in} order to gradually increase the air cooling capacity in the evaporator 3, and the required blowing temperature TA0 is further increased. Is higher than 45 ° C., the set refrigerant pressure PE0 is set to 1.85 kg / c to increase the air cooling capacity in the evaporator 3.
and m ^2. In this embodiment, the required blowing temperature T of 10 ° C.
A0 corresponds to the first reference value of the present invention, and the required blowing temperature TA0 of 35 ° C. corresponds to the second reference value of the present invention. 1.85kg / cm ²
As described above, the set refrigerant pressure PE0 of a value less than 3.0 g / cm ² corresponds to the first set value of the present invention, and the set refrigerant pressure PE0 of 3.0 kg / cm ²
Corresponds to the second set value of the present invention.

Next, the routine proceeds to step 104, where the difference Ec between the set refrigerant pressure PE0 determined in step 103 and the actual refrigerant pressure PE is determined.

Then, the routine proceeds to step 105, where a correction amount ΔVc of the refrigerant suction amount of the compressor 5 is calculated based on the difference Ec obtained in step 104.

Subsequently, the routine proceeds to step 106, where the refrigerant suction amount of the compressor 5 is changed and controlled based on the correction amount ΔVc calculated in step 105. That is, the amount of refrigerant sucked into the compressor 5 is changed and controlled so that the actual refrigerant pressure PE detected by the refrigerant pressure sensor 21 becomes the set refrigerant pressure PE0.

Further, the process proceeds to step 107, where the opening degree of the air mix damper 12 is calculated in order to adjust the temperature of the air blown into the vehicle interior 14.

Then, the process proceeds to step 108, in which the operation of the second servomotor 13 is controlled so that the opening calculated in step 107 is obtained, and the opening of the air mix damper 12 is controlled.

On the other hand, the ECU 27 switches the inside and outside air based on the setting signal from the mode setting switch 26, switches the air blowing position, and changes the air blowing amount, in order to perform the servo motors 11 and 16 via the drive circuit 28. A control signal is output to the blower 2.

Next, an operation of the vehicle air conditioner configured as described above according to the heat load state in each season will be described.

Now, at the detection values and the set values by the sensors 22 to 24 and the temperature setting switch 25, the inside air temperature Tr is 25 ° C., the solar radiation amount Ts
Is 10kcal / m ² min, outside air temperature is 35 ℃ and set temperature Tset
In the case of summer when a refrigerant such as 25 ° C is required,
The calculation result of the required blowing temperature TA0 by the ECU 27 is -17.5 ° C., and based on the map of FIG. 2, the set refrigerant pressure PE0 is 1.85 ° C.
kg / cm ² (equivalent to −3 ° C. as the evaporation temperature).

Accordingly, the ECU 27 calculates the actual refrigerant pressure P of the refrigerant pressure sensor 21.
The amount of refrigerant sucked into the compressor 5 is changed and controlled so that E becomes 1.85 kg / cm ² . As a result, the air cooling capacity of the evaporator 3 is increased, and the temperature of the air blown out of the evaporator 3 is reduced. In this case, the temperature of the air blown out from the evaporator 3 is cooled to the frost limit. ECU 27 is in the cabin 14
In order to control the temperature at which air is blown into the air, the opening of the air mix damper 12 is calculated to drive and control the second servo motor 13 to control the opening of the air mix damper 12.

As a result, cooling air of about 0 ° C. is blown into the vehicle interior 14 to perform cooling and dehumidification, and the vehicle interior 14 eventually reaches the set temperature Ts of 25 ° C.
kept in et.

On the other hand, the inside air temperature Tr is 25 ° C., the solar radiation Ts is 5 kcal / m ² min,
When the outside air temperature Tam is 20 ° C. and the set temperature Tset is 25 ° C. in the spring or autumn when solar radiation is weak, the calculation result of the required blowing temperature TA0 by the ECU 27 is 20 ° C., and the set refrigerant pressure PE0 is 3.0 kg / cm ² (Equivalent to 8 ° C. as the evaporation temperature).

Accordingly, the ECU 27 calculates the actual refrigerant pressure P of the refrigerant pressure sensor 21.
The amount of refrigerant sucked into the compressor 5 is controlled on the small capacity side so that E becomes 3.0 kg / cm ² . As a result, the air cooling capacity of the evaporator 3 is reduced, and the temperature of the air blown out of the evaporator 3 is increased. In this case, the temperature of the air blown from the evaporator 3 does not reach the frost limit. The ECU 27 controls the temperature of air blown into the vehicle interior 14 by using an air mix damper.
The second servo motor 13 is driven and controlled by calculating the opening of the air mixing damper 12, and the opening of the air mix damper 12 is controlled.

As a result, air at a temperature that is found in the spring or autumn is blown into the vehicle interior 14 to perform cooling and dehumidification, and the vehicle interior 14 is eventually maintained at the set temperature Tset of 25 ° C. In addition, since the compressor 5 is operated with a small amount of suction refrigerant, the power loss can be suppressed.

Further, the inside air temperature Tr is 25 ° C., the solar radiation Ts is 0 kcal / m ² min,
In the case of a winter night without solar radiation, such as when the outside air temperature Tam is 5 ° C. and the set temperature Tset is 25 ° C., the refrigerant load is considerably reduced, and the calculation result of the required blowing temperature TA0 by the ECU 27 is 47.
5 ° C., and the set refrigerant pressure PE0 becomes 1.85 kg / cm ² (equivalent to -3 ° C. as the evaporation temperature).

Accordingly, the ECU 27 calculates the actual refrigerant pressure P of the refrigerant pressure sensor 21.
The suction refrigerant amount of the compressor 5 is controlled so that E becomes 1.85 kg / cm ² . As a result, the air cooling capacity of the evaporator 3 is increased, and the temperature of the air blown out of the evaporator 3 is reduced.
In this case, the temperature of the air blown out of the evaporator 3 is cooled to the slost limit. The ECU 27 controls the temperature of air blown into the vehicle interior 14 by using an air mix damper.
The second servo motor 13 is driven and controlled by calculating the opening of the air mixing damper 12, and the opening of the air mix damper 12 is controlled.

As a result, air at the temperature that was found during the winter season is blown into the vehicle interior 14 to perform heating and dehumidification.
It is kept at the set temperature Tset of ° C.

At this time, the evaporation temperature of -3 ° C in the evaporator 3 is 5 ° C.
The outside air temperature is lower than the outside temperature Tam, so when the outside air temperature is high or the air conditioner is used for internal air circulation, etc., the interior of the vehicle interior 14 can be sufficiently dehumidified, preventing the fogging of the window glass before it occurs. can do.

Here, the outside air temperature Tam, the evaporation temperature, and the set refrigerant pressure PE
FIG. 3 shows the experimental results obtained by adjusting the relationship with 0. In this experiment, the air conditioner was used in an indoor air circulation system in a vehicle room without solar radiation, and under the severe conditions of four occupants. As shown in FIG. 3, it can be seen that the evaporation temperature and the set refrigerant pressure PE0 increase substantially in proportion to the rise in the outside air temperature Tam. The upper side of the graph is a fogged area of the window glass, and the lower side is a non-fogged area.

As is clear from this figure, when the outside air temperature Tam is 5 ° C., the evaporation temperature is about 4 ° C. and the set refrigerant pressure PE0 is 2.6 k
g / cm ² . This value is the set refrigerant pressure PE0 of 1.85 kg / cm ² determined under the above-mentioned winter conditions, or −3 ° C.
It can be seen that the fogging of the window glass can be reliably prevented by the operation of the air conditioner under the winter conditions because the temperature is higher than the evaporation temperature.

Note that the present invention is not limited to the above-described embodiment, and may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention.

(1) In the above-described embodiment, the internal temperature sensor 22, the solar radiation sensor 23, and the external temperature sensor 24 are provided as the thermal load detecting means for detecting the thermal load state of the vehicle. A temperature sensor 24 and a solar radiation sensor 23 may be combined, or a sensor for detecting the open / close position of the air mix damper 12, which is changed according to the heat load state, may be provided.

(2) In the above embodiment, the variable displacement type compressor 5 is provided as the suction refrigerant amount changing means for changing the suction refrigerant amount of the compressor. However, in order to turn on and off the drive connection between the compressor 5 and the engine 9. May be configured to change the intake refrigerant amount based on the on / off control of the electromagnetic clutch.

(3) In the above-described embodiment, the set refrigerant pressure PE0 with respect to the required blowing temperature TA0 corresponding to the cooling load is changed partially continuously as shown in the map of FIG.
As shown in the figure, the set refrigerant pressure PE0 may be changed stepwise according to the magnitude of the cooling load.

(4) In the above-described embodiment, the refrigerant pressure sensor 21 is provided at the outlet side of the evaporator 3 to detect the actual refrigerant pressure PE in order to detect the actual air cooling capacity of the evaporator 3. Alternatively, a sensor for detecting the temperature of the refrigerant of the evaporator 3 may be provided, a sensor for detecting the temperature of the blown air of the evaporator 3 may be provided, or a sensor for detecting the surface temperature of the fins of the evaporator 3 may be provided.

(5) In the above embodiment, the respective dampers 10, 12, 15 are configured to be automatically opened and closed by the operation of the respective servo motors 11, 13, 16; however, operating levers for the respective dampers 10, 12, 15 are provided. You may comprise so that it may open and close manually.

(6) In the above embodiment, the required blowing temperature corresponding to the cooling load is calculated based on the calculation formula (1).
The cooling load or a value corresponding thereto may be calculated based on a calculation formula other than the calculation formula (1).

(7) In the above embodiment, the first and second reference values of the present invention were set to 10 ° C. and 35 ° C. as the required blowing temperature TA0, respectively. 1.85kg / c as the first set value as the set refrigerant pressure PE0
m ² or more is set to a value of less than 3.0 kg / cm ^2, respectively set to 3.0 kg / cm ² and the second setting value as a setting refrigerant pressure PE0. On the other hand, the first and second reference values and the first and second set values are not limited to the above-described values, and can be appropriately set without departing from the spirit of the present invention. .

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to perform cooling and dehumidification in response to a change in the heat load state of a vehicle, and to reliably prevent fogging of a window glass, and An excellent effect of reducing the power loss for that purpose is exhibited.

[Brief description of the drawings]

1 to 4 are views showing an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of an air conditioner, and FIG. 2 is an evaporator corresponding to a required blowing temperature corresponding to a cooling load. A map showing the relationship between the set refrigerant pressure at the outlet, FIG. 3 is a graph showing the relationship between the evaporating temperature and the set refrigerant pressure with respect to the outside air temperature, and FIG. 4 is a flowchart for explaining the control operation in this air conditioner. FIG. 5 is a map showing the relationship between the set refrigerant pressure and the cooling load in another embodiment of the present invention, and FIG. 6 is a schematic configuration diagram of a conventional air conditioner. In the figure, 3 is an evaporator, 4 is a heater, 5 is a variable displacement compressor constituting suction refrigerant amount changing means, 6 is a condenser, 8 is an expansion valve as pressure reducing means, 22 is an internal temperature sensor, 23 is a solar radiation sensor, 24 is an outside air temperature sensor (22 to 24 constitute heat load detecting means), and 27 is an ECU which constitutes arithmetic means and first to third control means.

Claims (1)

(57) [Claims] 1. An air conditioner for a vehicle comprising a refrigeration cycle having a compressor, a condenser, a pressure reducing means, and an evaporator, wherein the compressor is used to change an air cooling capacity of the evaporator. Means for changing the amount of refrigerant sucked into the vehicle, heat load detecting means for detecting the heat load state of the vehicle, and calculation for calculating the cooling load in the vehicle cabin based on the value detected by the heat load detecting means. Means, and a cooling load calculated by the calculating means is a first predetermined value.
First control means for controlling the suction refrigerant amount changing means to adjust the air cooling capacity of the evaporator to a relatively high first set value when the reference value is larger than the reference value of When the cooling load calculated in the range from the first reference value to a predetermined second reference value smaller than the reference value, the air cooling capacity of the evaporator is set to the first set value. A second control means for controlling the suction refrigerant amount changing means to adjust to a lower second set value, and a cooling load calculated by the calculation means is smaller than the second reference value. And a third control means for controlling the suction refrigerant amount changing means in order to adjust the air cooling capacity of the evaporator to a value higher than the second set value. Air conditioner.