JP4269428B2 - Air conditioner for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle air conditioner that variably controls the rotational speed of an electric compressor.
[0002]
[Prior art]
Conventionally, in a vehicle air conditioner equipped with an electric compressor, the control target value (target evaporator outlet temperature) of the evaporator (indoor heat exchanger) outlet side temperature of the refrigeration cycle, regardless of the air inlet mode, It is determined uniformly according to the heat load (set temperature, internal / external air temperature, solar radiation).
[0003]
Further, in a heat pump type vehicle air conditioner equipped with an electric compressor, the refrigerant flow is switched between cooling and heating, and the refrigerant discharged from the compressor (hot gas) is supplied to the condenser of the refrigeration cycle (indoor heat) during heating. It is introduced directly into the exchanger, and the condenser radiates heat from the gas refrigerant to the conditioned air. And also in this heat pump type vehicle air conditioner, the control target value of the condenser outlet side temperature during heating is uniformly determined according to the heat load regardless of the inlet mode.
[0004]
[Problems to be solved by the invention]
Therefore, in any of the conventional apparatuses, for example, when the intake port mode is switched from the internal air mode to the external air mode in a state where the external air temperature is 35 ° C. and the internal air temperature is approximately 25 ° C., the intake air temperature is 25 The evaporator outlet temperature rises suddenly from ° C to 35 ° C, and the difference between the evaporator outlet temperature and the control target value of the evaporator outlet temperature suddenly increases. Therefore, in order to increase the heat exchange capability of the evaporator and bring the evaporator outlet temperature closer to the control target value, the electric compressor operates so that the rotational speed increases rapidly and the refrigerant discharge amount increases. Therefore, there is a problem that the operating noise of the electric compressor suddenly increases and the passenger feels uncomfortable.
[0005]
In the case of the latter conventional device, when switching from the inside air mode to the outside air mode during heating, the condenser outlet temperature decreases as the intake air temperature decreases, and the difference between the condenser outlet temperature and its control target value is It gets bigger. Therefore, in order to increase the heat exchange capability of the condenser and bring the condenser outlet temperature closer to the control target value, the rotational speed of the electric compressor rises rapidly, and the same problem as described above occurs.
[0006]
The present invention has been made in view of the above points. In a vehicle air conditioner equipped with an electric compressor, when the suction port mode is changed from the inside air mode to the outside air mode, the operating noise of the electric compressor rapidly increases. The purpose is to prevent.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the rotational speed of the electric compressor (41) is controlled based on a control target value of a physical quantity related to the heat exchange capability of the indoor heat exchanger (45). In the vehicle air conditioner, the outlet side temperature of the indoor heat exchanger (45) is controlled to be higher at the time of cooling in the outside air mode and when the outside air temperature is the predetermined temperature or higher than in the inside air mode. The target value is changed.
[0008]
As a result, when the inlet mode is changed from the inside air mode to the outside air mode in the cooling state, the physical quantity related to the heat exchange capability of the indoor heat exchanger (for example, the heat exchanger outlet side temperature) and the control target value of this physical quantity It is possible to prevent the difference from increasing rapidly, thereby suppressing an increase in the rotational speed of the electric compressor, and to reduce the sense of incongruity due to a sudden increase in operating noise of the electric compressor.
[0009]
In the invention according to claim 2, in the vehicle air conditioner for controlling the rotational speed of the electric compressor (41) based on the control target value of the physical quantity related to the heat exchange capability of the indoor heat exchanger (45), During heating, the control target value is changed so that the outlet side temperature of the indoor heat exchanger (45) is lower in the outside air mode than in the inside air mode.
[0010]
This prevents the difference between the physical quantity related to the heat exchange capacity of the indoor heat exchanger and the control target value of this physical quantity from rapidly increasing when the inlet mode is changed from the inside air mode to the outside air mode in the heating state. As a result, an increase in the rotational speed of the electric compressor can be suppressed, and a sense of incongruity due to a sudden increase in operating noise of the electric compressor can be reduced.
[0011]
According to a third aspect of the present invention, the indoor heat exchanger (45) is an evaporator that cools the air by the latent heat of vaporization of the refrigerant, and the control target value is changed only during cooling.
[0012]
Thereby, when heating is performed, the ability of the evaporator is not lowered even when the mode is switched to the outside air mode, so that the anti-fogging performance of the window glass in winter can be ensured.
[0013]
The invention according to claim 4 is characterized in that the change amount of the control target value is varied in accordance with the amount of air heat exchanged in the indoor heat exchanger (45).
[0014]
By the way, when the air inlet mode is changed from the inside air mode to the outside air mode, the difference between the physical quantity related to the heat exchange capability of the indoor heat exchanger and the control target value of this physical quantity increases as the amount of heat exchanged increases. However, the difference between the physical quantity and the control target value becomes excessive when the amount of air is large by varying the amount of change of the control target value in accordance with the amount of air. Therefore, it is possible to prevent a sudden increase in operating noise due to a sudden increase in the rotational speed of the electric compressor.
[0015]
In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows the overall configuration of an air conditioner according to an embodiment of the present invention. This air conditioner mounted on a hybrid vehicle including a traveling engine E and a traveling motor M is an air conditioner unit that air-conditions a vehicle interior. 1 and an air conditioner control device 2 that controls devices constituting the air conditioner unit 1. In this example, the air conditioner is an auto air conditioner that automatically controls the temperature of the passenger compartment to a set temperature that is arbitrarily set.
[0017]
The air conditioner unit 1 is disposed on the front side of the vehicle interior, and forms an air passage that guides air-conditioned air into the vehicle interior, a centrifugal blower 30 that sends air in the air-conditioner duct 10, and the air-conditioner duct 10 The refrigeration cycle 40 that cools the air flowing through the air conditioning duct 10 and the cooling water circuit 50 that heats the air flowing through the air conditioning duct 10 are included.
[0018]
The inside / outside air switching box provided on the most upstream side of the air flow of the air conditioning duct 10 has an inside air suction port 11 and an outside air suction port 12, and these suction ports 11, 12 are opened and closed by an inside / outside air switching damper 13. The This inside / outside air switching damper 13 is driven by an actuator (not shown) such as a servo motor, and the suction port modes are an inside air mode in which only the inside air suction port 11 is opened and an outside air mode in which only the outside air suction port 12 is opened. In addition, switching is possible.
[0019]
At the most downstream side of the air flow of the air conditioning duct 10, a defroster opening 15 that blows conditioned air toward the inner surface of the windshield of the vehicle, a face opening 16 that blows conditioned air toward the upper body of the occupant, Foot outlets 17 that blow out the conditioned air toward the feet are opened. And the opening switching dampers 18-20 which open and close each opening part independently are attached to each opening part 15-17 so that rotation is possible. These blower outlet switching dampers 18 to 20 are respectively driven by an actuator (not shown) such as a servo motor, and the blower outlet modes are set to a face mode, a bi-level mode, a foot mode, a foot differential mode, and a defroster mode. Switch to one.
[0020]
The blower 30 includes a centrifugal fan 31 that is rotatably housed in a scroll case that is integrally formed with the air conditioning duct 10, and a blower motor 32 that rotationally drives the centrifugal fan 31. The blower motor 32 controls the air flow rate (the rotational speed of the centrifugal fan 31) based on the blower terminal voltage applied via the blower drive circuit 33.
[0021]
The refrigeration cycle 40 condenses and liquefies the refrigerant by exchanging heat between the compressed refrigerant and the outside air, and an electric compressor 41 including a compression mechanism that compresses the refrigerant and a motor that receives power from the battery 3 and drives the compression mechanism. Condenser 42, a gas-liquid separator 43 that gas-liquid separates the condensed and liquefied refrigerant and flows only the liquid refrigerant downstream, an expansion valve 44 that decompresses and expands the liquid refrigerant, and exchanges heat between the decompressed and expanded refrigerant and the conditioned air The refrigerant is composed of an evaporator (indoor heat exchanger) 45 that cools the conditioned air by the latent heat of evaporation of the refrigerant, a cooling fan 46 that blows outside air to the condenser 42, and a refrigerant pipe that connects them. An AC voltage is applied to the motor of the electric compressor 41 via the inverter 47, and the inverter 47 adjusts the frequency of the AC voltage based on a command from the air conditioner control device 2, thereby continuously increasing the rotational speed of the electric compressor 41. It is supposed to change.
[0022]
The cooling water circuit 50 includes a heater core 51 disposed in a circuit that circulates the cooling water (hot water) of the engine E by a water pump (not shown). The heater core 51 exchanges heat between the engine cooling water and the conditioned air. Heat. The heater core 51 is disposed downstream of the evaporator 45 in the air conditioning duct 10 so as to partially block the air passage. An air mix damper 52 is rotatably mounted in the vicinity of the heater core 51, and the air mix damper 52 is driven by an actuator (not shown) such as a servo motor so that the warm air passing through the heater core 51 and the heater core 51. The temperature of the air blown into the passenger compartment is adjusted by adjusting the ratio of the cool air that bypasses the vehicle.
[0023]
Next, the air conditioner control device 2 receives switch signals from switches on an air conditioner operation panel (not shown) provided on the front surface of the vehicle interior and sensor signals from various sensors (not shown). . Here, each switch on the air conditioner operation panel refers to an air conditioner switch for instructing activation and stop of the refrigeration cycle 40 (electric compressor 41), a suction port changeover switch for switching a suction port mode, and a temperature in the passenger compartment. A temperature setting lever for setting the air flow to a desired temperature, an air volume switching lever for switching the air flow rate of the centrifugal fan, an air outlet changeover switch for switching the air outlet mode, and the like.
[0024]
The various sensors include an inside air temperature sensor that detects the air temperature inside the vehicle interior, an outside air temperature sensor that detects the air temperature outside the vehicle interior, a solar radiation sensor that detects the amount of solar radiation irradiated into the vehicle interior, and the evaporator 45 An evaporator inlet temperature sensor for detecting the temperature of the air to be discharged (evaporator inlet temperature), an evaporator outlet temperature sensor for detecting the air temperature (evaporator outlet temperature) immediately after passing through the evaporator 45, and cooling flowing into the heater core 51 A water temperature sensor that detects the temperature of water, a vehicle speed sensor that detects the traveling speed of the vehicle, and the like.
[0025]
Inside the air conditioner control device 2, a microcomputer comprising a CPU, ROM, RAM, etc. (not shown) is provided, and sensor signals from each sensor are A / D converted by an input circuit (not shown) in the air conditioner control device 2. It is configured to be input to the microcomputer later. The air conditioner control device 2 operates by being supplied with DC power from the battery 3 when the ignition switch of the vehicle is turned on.
[0026]
Next, control processing of the air conditioner control device 2 will be described with reference to FIGS. Here, FIG. 2 is a flowchart showing basic control processing by the air conditioner control device 2. First, when the ignition switch is turned on and DC power is supplied to the air conditioner control device 2, the routine of FIG. 2 is started to perform each initialization and initial setting (step S1). Subsequently, a switch signal is read from each switch such as a temperature setting lever (step S2). Subsequently, a signal obtained by A / D converting sensor signals from the inside air temperature sensor, the outside air temperature sensor, the solar radiation sensor, the evaporator inlet temperature sensor, the evaporator outlet temperature sensor, the water temperature sensor, and the vehicle speed sensor is read (step S3).
[0027]
Subsequently, a target blowing temperature TAO of air blown into the passenger compartment is calculated based on the following equation 1 stored in advance in the ROM (step S4).
[0028]
[Expression 1]
TAO = Kset × Tset−KR × TR-KAM × TAM-KS × TS + C
Here, Tset is the set temperature set by the temperature setting lever, TR is the inside air temperature detected by the inside air temperature sensor, TAM is the outside air temperature detected by the outside air temperature sensor, and TS is the amount of solar radiation detected by the solar radiation sensor. is there. Kset, KR, KAM, and KS are gains, and C is a correction constant.
[0029]
Subsequently, a blower voltage (voltage applied to the blower motor 32) is determined based on the target blowing temperature TAO from a characteristic diagram stored in advance in the ROM (step S5). Specifically, the lower the target blowing temperature TAO, the higher the blower voltage (the larger the air volume), and the lower the target blowing temperature TAO, the lower the blower voltage. Subsequently, the suction port mode is determined based on the target outlet temperature TAO from the characteristic chart stored in advance in the ROM (step S6). Specifically, the inside air circulation mode is selected when the target blowing temperature TAO is low, and the outside air introduction mode is selected when the target blowing temperature TAO is high.
[0030]
Subsequently, the outlet mode is determined based on the target outlet temperature TAO from the characteristic chart stored in advance in the ROM (step S7). Specifically, the foot mode is selected when the target blowing temperature TAO is high, and the bi-level mode is selected in the order of the face mode as the target blowing temperature TAO becomes low. Subsequently, the opening degree of the air mix damper 52 is determined based on the target blowing temperature TAO, the evaporator outlet temperature, the cooling water temperature, and the like (step 8).
[0031]
Subsequently, in step S9, the subroutine shown in FIG. 3 is called, and the target evaporator outlet temperature (control target value) TEO, which is the control target of the air temperature (evaporator outlet temperature TOUT) immediately after passing through the evaporator 45, is determined. Is done. Subsequently, the rotational speed of the electric compressor 41 is determined based on the evaporator outlet temperature TOUT and the target evaporator outlet temperature TEO (step S10). Subsequently, a control signal is output to the actuator, the blower drive circuit 33 and the inverter 47 so that the control states calculated or determined in steps 4 to 10 are obtained (step S11).
[0032]
Next, the control process for determining the target evaporator outlet temperature TEO in step S9 will be described with reference to FIG. First, in step S91, the suction port mode is determined, and if it is the outside air mode, the process proceeds to step S92, and if it is the inside air mode, the process proceeds to step S93. In step S92, it is determined whether or not the outside air temperature TAM is 20 ° C. or higher. If the determination result in step 92 is YES, the process proceeds to step 94. If the determination result in step 92 is NO, the process proceeds to step 93.
[0033]
In step S93 and step 94, the target evaporator outlet temperature TEO is determined from the characteristic diagrams of FIGS. 4 and 5 stored in advance in the ROM. Here, in step S93, the target evaporator outlet temperature TEO is calculated based on the characteristic line a (solid line) of the first target evaporator outlet temperature in FIG. 4 and the target outlet temperature TAO, and the first target evaporation in FIG. The target evaporator outlet temperature TEO is calculated based on the characteristic line c (solid line) of the outlet temperature of the evaporator and the outside air temperature TAM, and the lower one of the two target evaporator outlet temperatures TEO is used as the first target evaporator outlet temperature. decide.
[0034]
On the other hand, in step S94, the target evaporator outlet temperature TEO is calculated based on the characteristic line b (one-dot chain line) of the second target evaporator outlet temperature in FIG. 4 and the target outlet temperature TAO, and the second target evaporation in FIG. The target evaporator outlet temperature TEO is calculated based on the characteristic line d (one-dot chain line) of the outlet temperature of the evaporator and the outside air temperature TAM, and the lower value of the two target evaporator outlet temperatures TEO is calculated as the second target evaporator outlet temperature. Determine as.
[0035]
By the control processing of step S9, when the outside air mode (step 91 is YES) and the outside air temperature TAM is 20 ° C. or higher (step 92 is YES), the inside air mode and the outside air temperature TAM are less than 20 ° C. The target evaporator outlet temperature TEO is set high in a partial region (when the target blowout temperature TAO is low and when the outside air temperature TAM is high). In this region, the target evaporator outlet temperature TEO is set high. The heat exchange capacity of the vessel 45 is slightly reduced.
[0036]
Next, the operation of the air conditioner configured as described above will be described. The air flowing in the duct 10 by the blower 30 is cooled by exchanging heat with the refrigerant when passing through the evaporator 45 in the refrigeration cycle 40. Here, the flow rate of the refrigerant flowing in the refrigeration cycle 40 is controlled by controlling the rotation speed of the electric compressor 41 by the air conditioner control device 2, and the cooling performance (heat exchange capacity) of the refrigeration cycle 40 is adjusted. Yes.
[0037]
The air cooled by the evaporator 45 is heated by exchanging heat with the engine coolant when passing through the heater core 51 in the coolant circuit 50. The ratio of the air passing through the heater core 51 and the air bypassing the heater core 51 is adjusted according to the opening position of the air mix damper 52, and thus the conditioned air adjusted to a predetermined temperature is supplied to each of the openings 15 to 17. Blow out from one or two of them.
[0038]
And, for example, when the air inlet mode is switched from the inside air mode to the outside air mode in the state where the outside air temperature TAM is 35 ° C. and the inside air temperature TR is cooled to about 25 ° C., it is determined in step 94 of FIG. 2 The target evaporator outlet temperature is adopted as the target evaporator outlet temperature TEO, and the rotational speed of the electric compressor 41 is determined based on the evaporator outlet temperature TOUT and the target evaporator outlet temperature TEO in step S10.
[0039]
Here, since the second target evaporator outlet temperature in the outside air mode is set higher than the first target evaporator outlet temperature in the inside air mode, the target evaporator is changed with the change from the inside air mode to the outside air mode. The outlet temperature TEO is changed to a higher value. Even if the intake air temperature suddenly changes from 25 ° C. to 35 ° C. and the evaporator outlet temperature TOUT rises, the target evaporator outlet temperature TEO is changed to a higher value as described above. An increase in the difference between the temperature TOUT and the target evaporator outlet temperature TEO can be suppressed. Therefore, an excessive increase in the rotational speed of the electric compressor 41 can be suppressed, and a sudden change in operating noise due to an increase in the rotational speed of the electric compressor 41 can be prevented.
[0040]
On the other hand, in the state where the outside air temperature TAM is less than 20 ° C. and heating is performed, even if the suction port mode is switched from the inside air mode to the outside air mode, step 92 in FIG. 3 becomes NO, and the target evaporator outlet temperature TEO Is not changed. Accordingly, when heating is performed, the ability of the evaporator 45 does not decrease even when the mode is switched to the outside air mode, and the antifogging performance of the window glass in winter can be ensured.
(Second Embodiment)
The second embodiment shown in FIGS. 6 to 8 is a characteristic of the second target evaporator outlet temperature used in the outside air mode and the outside air temperature TAM is 20 ° C. or higher in the characteristic diagrams of FIGS. 4 and 5 in the first embodiment. The lines b and d are changed according to the blower voltage (air flow rate).
[0041]
Specifically, as shown in FIG. 6, the lowest target evaporator outlet temperature Tf in the outside air mode is set higher as the blower voltage becomes higher (as the air volume becomes larger). Therefore, as shown in FIG. 7, the characteristic line b of the second target evaporator outlet temperature obtained based on the target blowing temperature TAO is the one-dot chain characteristic line b when the blower voltage is low (the air volume is small). When the blower voltage is high (the air volume is large), a two-dot chain characteristic line b ′ is used. Further, as shown in FIG. 8, the characteristic line d of the second target evaporator outlet temperature obtained based on the outside air temperature TAM is the one-dot chain line characteristic line d when the blower voltage is low (the air volume is small). When the voltage is high (the air volume is large), a two-dot chain characteristic line d ′ is used. 7 and 8 exemplify two characteristic lines for the second target evaporator outlet temperature. Actually, the minimum target evaporator outlet temperature Tf is continuously changed according to the blower voltage as shown in FIG. Correspondingly, the characteristic line of the second target evaporator outlet temperature is continuously changed.
[0042]
By the way, when the suction port mode is switched from the inside air mode to the outside air mode, the evaporator outlet temperature TOUT tends to rise as the amount of air blown by the blower 30 increases, and accordingly, the evaporator outlet temperature TOUT and the target evaporator outlet temperature TEO Therefore, when the normal control is performed, the increase in the rotational speed of the electric compressor 41 is particularly large when the outside air mode is switched when the air flow rate is large.
[0043]
Therefore, in the present embodiment, as described above, the target evaporator outlet temperature TEO is increased by setting the minimum target evaporator outlet temperature Tf in the outside air mode higher as the blower voltage becomes higher (as the air volume increases). The difference between the evaporator outlet temperature TOUT and the target evaporator outlet temperature TEO is prevented from becoming excessive, and a sudden increase in operating noise due to an increase in the rotational speed of the electric compressor 41 is prevented. .
(Other embodiments)
In the above embodiment, an example in which the present invention is applied to a vehicle air conditioner including the heater core 51 has been described. However, the compressor discharge gas refrigerant (hot gas) is directly supplied to the condenser (indoor heat exchanger) of the refrigeration cycle. The present invention is also applicable to a vehicle air conditioner that is introduced and obtains a heating function by dissipating heat from the gas refrigerant to the conditioned air with this condenser. In this case, the same control as in the above embodiment is performed during cooling, and during heating, the control target value of the condenser outlet side temperature (or the high pressure side pressure of the refrigeration cycle) is lower in the outside air mode than in the inside air mode. Change to
[0044]
The present invention is also applicable to a so-called reheat type vehicle air conditioner that adjusts the temperature of conditioned air by adjusting the amount of hot water supplied to the heater core with a flow rate adjusting valve.
[0045]
In addition, the present invention recirculates the high-temperature indoor air heated from the foot opening by partitioning the air passage in the air conditioning duct into a first air passage on the inside air side and a second air passage on the outside air side. On the other hand, it is also applicable to a vehicle air conditioner in which a so-called inside / outside air two-layer flow mode can be set, in which low humidity outside air is blown out from the opening of the defroster.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of an air conditioner according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing a basic control process of the air conditioner control device shown in FIG. 1;
FIG. 3 is a flowchart showing a control process in step S9 of FIG.
FIG. 4 is a control characteristic diagram of a target evaporator outlet temperature TEO used in the first embodiment.
FIG. 5 is a control characteristic diagram of a target evaporator outlet temperature TEO used in the first embodiment.
FIG. 6 is a control characteristic diagram of a minimum target evaporator outlet temperature Tf in the outside air mode used in the second embodiment of the present invention.
FIG. 7 is a control characteristic diagram of a target evaporator outlet temperature TEO used in the second embodiment.
FIG. 8 is a control characteristic diagram of a target evaporator outlet temperature TEO used in the second embodiment.
[Explanation of symbols]
41 ... Electric compressor, 45 ... Evaporator (indoor heat exchanger).

Claims (4)

An electric compressor (41) for compressing the refrigerant, and an indoor heat exchanger (45) for exchanging heat between the refrigerant from the electric compressor (41) and air, the indoor heat exchanger (45) In the vehicle air conditioner for controlling the rotational speed of the electric compressor (41) based on a control target value of a physical quantity related to heat exchange capacity,
During cooling, the control target value is set so that the outlet side temperature of the indoor heat exchanger (45) becomes higher when the outside air mode is higher than the predetermined temperature, and when the outside air temperature is equal to or higher than the predetermined temperature. The air conditioner for vehicles characterized by changing. An electric compressor (41) for compressing the refrigerant, and an indoor heat exchanger (45) for exchanging heat between the refrigerant from the electric compressor (41) and air, the indoor heat exchanger (45) In the vehicle air conditioner that controls the number of revolutions of the electric compressor (41) based on a control target value of a physical quantity related to heat exchange capacity, when heating, in the outside air mode than in the inside air mode, The vehicle air conditioner characterized in that the control target value is changed so that the outlet side temperature of the indoor heat exchanger (45) is lowered. The indoor heat exchanger (45) is an evaporator that cools air by the latent heat of vaporization of the refrigerant,
The vehicle air conditioner according to claim 1, wherein the control target value is changed only during cooling. 4. The vehicle according to claim 1, wherein a change amount of the control target value is varied in accordance with an amount of air to be heat exchanged in the indoor heat exchanger (45). Air conditioner.

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