JP2005219646A - Vehicular air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular air conditioner capable of controlling a temperature and humidity in a cabin to be suitable and securely avoiding dew condensation on a windowpane. <P>SOLUTION: When absolute humidity in a cabin Xr is higher than calculated windowpane dew point absolute humidity in a cabin Xrmax (step S21), the air conditioner determines that the windowpane may be misted after continuing this status for a predetermined continuing determination time T (step S23) and forcibly carries out control for switching to a mode for opening a blow-out port on the windowpane side (step S24). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle air conditioner that controls a cooling means and a heating means and performs air conditioning control in a vehicle compartment in a state in which window glass is not condensed.

  A vehicle air conditioner combines an evaporator that cools air using the vaporization heat of a refrigerant and dehumidifies it with a heater that heats air using the heat of engine cooling water. Adjust temperature and humidity.

  By the way, when the temperature is low and the control is performed so that the cooling capacity by the evaporator is lowered, the dehumidifying action is also reduced. For example, in a state where the temperature is low and the humidity is high, the water vapor in the passenger compartment becomes window glass or the like. There is a possibility of condensation.

  Therefore, for example, in the prior art disclosed in Patent Document 1, the interior surface temperature of the window glass is estimated from the outside air temperature and the interior temperature, and the required humidity of the blown air that becomes the interior humidity without condensation at this temperature is calculated. And then calculating the dew point temperature of the air indicating the calculated required blown air required humidity, and determining the lower one of the required blown air temperature and the dew point temperature required to control the cabin temperature to the set temperature. The control is performed so that the control temperature is set to.

Japanese Patent No. 3298151 (paragraphs [0009] and [0024])

  However, for example, if there is a sudden change in driving conditions such as the traveling speed of the vehicle or environmental conditions such as rain or snow, the estimation accuracy of the surface temperature of the vehicle interior of the window glass decreases, and the window glass condenses. There is a fear.

  The present invention has been made to solve the above-mentioned problems, and it is possible to control the interior of the vehicle to an appropriate temperature and humidity, and to reliably avoid condensation on the window glass. The purpose is to provide.

In order to achieve the above object, the present invention provides a vehicle air conditioner that controls the cooling means and the heating means to control the air conditioning in the passenger compartment.
A window glass vehicle interior surface temperature acquisition means for acquiring the window glass vehicle interior surface temperature;
Window glass dew point vehicle interior absolute humidity obtaining means for obtaining window glass dew point vehicle interior absolute humidity Xrmax with the window glass vehicle interior surface temperature as a dew point;
Vehicle interior absolute humidity acquisition means for acquiring vehicle interior absolute humidity Xr;
Continuation time determining means for determining whether or not the state of Xrmax ≦ Xr continues for a predetermined time or more;
When it is determined that the state of Xrmax ≦ Xr has continued for a predetermined time or more, the outlet switching means for switching to the outlet for blowing air to the window glass,
It is characterized by providing.

  In this case, when it is determined that the window glass is likely to condense, it is possible to avoid condensation in advance by forcing air to the window glass.

  According to the present invention, the window glass does not condense regardless of abrupt changes in operating conditions and environmental conditions, and the vehicle interior can be air-conditioned to an appropriate temperature and humidity.

  FIG. 1 shows a vehicle 12 equipped with a vehicle air conditioner 10 of the present embodiment. As shown in FIG. 2, the vehicle air conditioner 10 includes an air conditioner ECU (Electronic Control Unit) 14 and an air conditioner unit 16 that adjusts the temperature, humidity, and air flow rate of air based on the control of the air conditioner ECU 14. The air conditioning unit 16 is supplied with cooling water from the engine 18.

  The air conditioner ECU 14 is connected to an operation display unit 20 for accepting operations such as temperature setting, air flow setting, and mode switching by an occupant of the vehicle 12 and displaying set temperature, air flow setting, setting mode, and the like.

  The air conditioner ECU 14 includes an outside air temperature sensor 22 that detects the outside air temperature of the vehicle 12, a solar radiation amount sensor 24 that detects the amount of solar radiation, a cooling water temperature sensor 26 that detects the temperature of the cooling water supplied from the engine 18, and the vehicle. A vehicle interior temperature sensor 28 for detecting the vehicle interior temperature 12 and a vehicle interior humidity sensor 30 for detecting the vehicle interior humidity of the vehicle 12 are connected.

  Further, the air conditioner ECU 14 is connected to an outside / inside air switching damper driving unit 32, a blower driving unit 34, an air mix damper driving unit 36, and a mode switching damper driving unit 38 that constitute the air conditioning unit 16.

  The air conditioner unit 16 has an outside air intake port 40 that takes in outside air or inside air, and air outlets 42, 44, and 46 for supplying air adjusted in temperature, humidity, and air flow rate to a predetermined part in the vehicle interior. A duct 48 is provided. An outside / inside air switching damper 50 that is driven by the outside / inside air switching damper driving unit 32 and switches between outside air and inside air is disposed in the outside / inside air intake port 40. Mode switching dampers 52 and 54 that are driven by a mode switching damper drive unit 38 and that switch between the outlets 42, 44, and 46 on the defroster side, the face side, and the foot side in the passenger compartment are arranged at the outlets 42, 44, and 46, respectively. Established. The window glass 31 of the vehicle 12 is close to the air outlet 42 on the defroster side.

  Inside the duct 48, a blower 56 driven by the blower drive unit 34 is disposed in the vicinity of the outside air intake port 40. An evaporator 58 that cools and dehumidifies the blown air is disposed on the downstream side of the air blown by the blower 56 and in the internal intermediate portion of the duct 48. A heater 60 that heats the air that has passed through the evaporator 58 with cooling water supplied from the engine 18 is disposed between the evaporator 58 and the outlets 42, 44, and 46. In this case, an air mix damper 62 that is driven by the air mix damper driving unit 36 and adjusts the supply amount of the air that has passed through the evaporator 58 to the heater 60 is disposed between the evaporator 58 and the heater 60. Is done.

  On the air outlet side of the evaporator 58, an evaporator outlet temperature detection sensor 66 for detecting the evaporator outlet temperature of air is disposed. The evaporator outlet temperature detection sensor 66 is connected to the air conditioner ECU 14.

  The air conditioner unit 16 is driven by the rotational force of the engine 18 to compress the refrigerant 68, the condenser 70 that condenses the refrigerant compressed by the compressor 68, and the refrigerant condensed by the condenser 70. A gas-liquid separator 72 that separates the liquid component and the gas component and an expansion valve 74 that expands the gas component of the refrigerant separated by the gas-liquid separator 72 and supplies the expanded gas component to the evaporator 58 are provided. Note that the refrigerant supplied to the evaporator 58 is circulated and supplied to the compressor 68.

  The vehicle air conditioner 10 according to the present embodiment is basically configured as described above. Next, the operation thereof will be described with reference to the flowchart shown in FIG.

  First, an occupant of the vehicle 12 operates the operation display unit 20 after turning on the power supply of the vehicle air conditioner 10 to set a desired air flow rate and temperature, the outside / inside air switching damper 50, and the mode switching dampers 52 and 54. Air conditioning conditions such as mode setting by adjustment are set (step S1).

  When the air conditioning conditions are set, the air conditioner ECU 14 sets the number of calculations N for air conditioning control to 0 (step S2), and then the outside air temperature sensor 22, the solar radiation amount sensor 24, the cooling water temperature provided in the vehicle 12 Each sensor information is read from the sensor 26, the vehicle interior temperature sensor 28, the vehicle interior humidity sensor 30, and the evaporator outlet temperature detection sensor 66 (step S3).

Next, the air conditioner ECU 14 acquires the vehicle interior surface temperature Tn of the window glass 31 (step S4). In this case, as the vehicle interior surface temperature Tn, the outdoor air temperature Tam detected by the outdoor air temperature sensor 22 can be set as the vehicle interior surface temperature Tn. The vehicle interior surface temperature Tn includes the outdoor air temperature Tam detected by the outdoor air temperature sensor 22, the vehicle interior temperature Tr detected by the vehicle interior temperature sensor 28, the solar radiation amount Ts detected by the solar radiation sensor 24, and the window glass 31. Using parameters k1 to k3 determined by the thickness, glass thermal conductivity, glass surface area, outside air side heat transfer coefficient, vehicle interior heat transfer coefficient, etc.,
Tn = k1, Tr + k2, Tam + k3, Ts (1)
Can be calculated as Further, when considering that the temperature of the window glass 31 is not uniform in the thickness direction and there is a transitional change, the vehicle interior surface temperature Tn calculated by the equation (1) is used as the vehicle interior surface temperature in a stable state. Tna, where the initial value of the calculation is Tn1, the vehicle interior surface temperature Tn in a transitional state at time t,
Tn = Tna− (Tna−Tn1) · exp (−α · t) (2)
Can be calculated as Α is a parameter determined by physical characteristics including the window glass 31. Furthermore, if a temperature sensor is directly attached to the window glass 31 for detection, the vehicle interior surface temperature Tn can be obtained more accurately.

  Next, from the vehicle interior surface temperature Tn acquired as described above, using the wet air diagram shown in FIG. 4, the window glass dew point vehicle interior that is the limit vehicle interior absolute humidity at which the vehicle interior surface of the window glass 31 does not condense. Absolute humidity Xrmax is obtained (step S5).

  Here, the wet air diagram represents a relationship between physical conditions such as air temperature (° C.), absolute humidity (kg / kg), relative humidity (%), and enthalpy of the air. The window glass dew point vehicle interior absolute humidity Xrmax may be expressed by a polynomial expression of the relationship between the air temperature and the absolute humidity when the relative humidity is 100%, and may be obtained by calculation using the window glass vehicle interior surface temperature Tn as a variable. The relationship may be stored as a look-up table and may be obtained as the window glass dew point vehicle interior absolute humidity Xrmax corresponding to the acquired window glass vehicle interior surface temperature Tn.

  Next, the vehicle interior set absolute humidity Xset within a range where the window glass 31 does not condense and the vehicle interior feels comfortable is obtained (step S6).

  Therefore, the air conditioner ECU 14 uses the vehicle interior set temperature Tset that is set by the occupant using the operation display unit 20 and the vehicle interior upper limit relative humidity that are set in advance from the wet air diagram shown in FIG. The vehicle interior set absolute humidity (temporary Xset) is obtained. Note that the vehicle interior upper limit relative humidity can be set to, for example, approximately 60%, which is the upper limit relative humidity that humans feel comfortable. The passenger compartment upper limit relative humidity may be set arbitrarily by the occupant by providing a setting unit in the operation display unit 20, for example.

  In this case, the relationship between the two variables of air temperature and relative humidity and the absolute humidity is expressed by a polynomial, and the provisional vehicle interior set absolute humidity (provisional Xset) is calculated by calculation using the vehicle interior set temperature Tset and the vehicle interior upper limit relative humidity as variables. Alternatively, this relationship may be stored as a lookup table for each relative humidity, and the provisional vehicle interior set absolute humidity (temporary Xset) may be obtained from the lookup table for the selected relative humidity.

  Next, the window glass dew point vehicle interior absolute humidity Xrmax and the temporary vehicle interior set absolute humidity (temporary Xset) are compared. In this case, if Xrmax> temporary Xset, even if the air in the temporary vehicle cabin set absolute humidity (temporary Xset) is cooled in the vicinity of the window glass, the air does not exceed 100% relative humidity. The glass will not fog up. In addition, the humidity in the passenger compartment is within a range where comfort is felt. On the other hand, if Xrmax ≦ temporary Xset, if the air in the provisional vehicle interior set absolute humidity (temporary Xset) is cooled in the vicinity of the window glass, the air will exceed 100% relative humidity, so that the window glass has dew condensation. It will occur.

  When Xrmax> provisional Xset, Xset = provisional Xset, and when Xrmax ≦ temporary Xset, Xset = Xrmax. By setting the vehicle interior set absolute humidity Xset in this way, the cooling capacity of the compressor 68 is minimized, condensation does not occur on the window glass, and the vehicle interior can be made comfortable humidity. .

  Next, the required air temperature Tao and the required air outlet absolute humidity Xao from the air outlets 42, 44 or 46 necessary for realizing the vehicle interior set temperature Tset and the vehicle interior set absolute humidity Xset are calculated (step S7, S8).

The required air temperature Tao is detected by the passenger compartment set temperature Tset set by the passenger, the passenger compartment temperature Tr detected by the passenger compartment temperature sensor 28, the outdoor air temperature Tam detected by the outdoor air temperature sensor 22, and the solar radiation sensor 24. Using the amount of solar radiation Ts
Tao = Ktset / Tset / Ktr / Tr-Ktam / Tam
−Kts · Ts−Ct (3)
Ktset: Car interior set temperature coefficient
Ktr: Vehicle interior temperature sensor coefficient
Ktam: outside temperature sensor coefficient
Kts: Solar radiation sensor coefficient
Ct: calculated as a temperature calculation coefficient.

Further, the required absolute humidity Xao for the blown air is obtained by using the vehicle interior absolute humidity Xset obtained in step S6 and the vehicle interior absolute humidity Xr detected by the vehicle interior humidity sensor 30.
Xao = Kxset, Xset-Kxr, Xr-Kxam, Tam-Cx1
(4)
Kxset: Car interior setting absolute humidity coefficient
Kxr: Absolute humidity coefficient in the passenger compartment
Kxam: outside air absolute humidity coefficient
Cx1: calculated as a humidity calculation coefficient. When the vehicle interior humidity sensor 30 is a sensor that detects relative humidity, the vehicle interior temperature sensor 28 detects the vehicle interior temperature Tr and the vehicle interior humidity sensor 30 detects the relative humidity. The vehicle interior absolute humidity Xr can be obtained from the wet air diagram shown.

  Using the blown air required temperature Tao and the blown air required absolute humidity Xao calculated as described above, a control temperature Tea that can minimize the operating rate of the compressor 68 is calculated (step S9). Therefore, the procedure for calculating the control temperature Tea will be described with reference to the flowchart shown in FIG.

  When the compressor 68 is a fixed capacity type and is connected to the engine 18 via a clutch, the control temperature Tea is a value detected by the evaporator outlet temperature detection sensor 66 when the compressor 68 is disconnected from the engine 18. The detected value of the evaporator outlet temperature detection sensor 66 when the compressor 68 is connected to the engine 18 is Tea + ε (ε: constant). Further, when the compressor 68 is a variable capacity type, the control temperature Tea is set to a detection value of the evaporator outlet temperature detection sensor 66.

  The window window dew point vehicle interior absolute humidity Xrmax obtained in step S5 is compared with the vehicle interior absolute humidity Xr detected by the vehicle interior humidity sensor 30, and if Xrmax ≦ Xr (step S21), the air in the vehicle interior is the window glass. If it is cooled in the vicinity, there is a possibility that condensation will occur on the window glass 31.

  Therefore, 1 is added to the number of calculations N for air conditioning control (step S22), each sensor information is read in step S3, and then the window glass dew point vehicle interior absolute humidity Xrmax and vehicle interior absolute humidity Xr are calculated in step S21. The time N · Δt during which the state of Xrmax ≦ Xr is continued is compared with the continuation determination time T, where Δt is the calculation time required for the processing until the comparison is made (step S23).

  If N · Δt ≧ T, it is determined that the window glass 31 may be fogged, and the mode switching damper 52 is set so that the air outlet 42 on the side of the window glass 31 is opened (step S24). If N · Δt <T, the mode switching damper 52 remains set by the occupant.

  In this case, for example, the operating conditions such as the traveling speed of the vehicle 12 and the environmental conditions such as rain and snow change suddenly, the temperature of the window glass 31 decreases, and the value of the acquired window glass dew point vehicle interior absolute humidity Xrmax However, even if it becomes lower than the actual humidity, air can be forcibly blown onto the window glass 31 in advance, so that there is no risk of condensation. If the mode switching damper 52 is controlled and the mode switching damper 54 is controlled so that air is blown out from both the air outlets 42 and 46, the condensation of the window glass 31 is prevented without impairing the comfort of the passenger. It can be avoided.

  Then, after Xrmax ≦ Xr and the switching mode is set as described above, the control temperature Tea is set to the lower limit temperature min at which the evaporator 58 is not frosted in order to maximize the dehumidifying ability by the evaporator 58. Set (step S25).

  On the other hand, if Xrmax> Xr (step S21), even if the air in the passenger compartment is cooled in the vicinity of the window glass, the air does not exceed 100% relative humidity, so the window glass does not fog up. . Therefore, after resetting the number of operations N to 0 (step S26), assuming that the margin for temperature is δ and the margin for humidity is γ, (Tset−δ)> Tr (step S27) and (Xset−γ)> Xr In this case (step S28), there is no need for further dehumidification in the current state, and there is no need for further cooling, so that the driving state of the compressor 68 is minimized. = Β (for example, about 20 ° C.) (step S29).

  If Xrmax> Xr (step S21), (Tset−δ) ≦ Tr (step S27), and (Xset−γ)> Xr (step S30), it is determined that cooling is necessary. . At this time, a margin for the necessary air temperature Tao is set as α, and Tea = Tao−α is set (step S31).

  If Xrmax> Xr (step S21), (Tset−δ)> Tr (step S27), and (Xset−γ) ≦ Xr (step S28), it is determined that dehumidification is necessary. . At this time, Ta = T (Xao) −η is set, where T (Xao) is a temperature at which the required relative humidity Xao is 100% relative humidity, and T is a calculation coefficient of temperature T (Xao) (step S32). .

  Furthermore, if Xrmax> Xr (step S21), (Tset−δ) ≦ Tr (step S27), and (Xset−γ) ≦ Xr (step S30), it is determined that cooling and dehumidification are necessary. Is done. At this time, Tao-α and T (Xao) -η are compared (step S33), and the smaller one is set as the control temperature Tea (steps S31 and S32).

  After the control temperature Tea is set as described above, if the compressor 68 is a variable capacity type, the capacity is adjusted (step S10). Further, the air conditioner ECU 14 calculates the opening degree of the air mix damper 62 and drives the air mix damper driving unit 36 to adjust the opening degree of the air mix damper 62 (step S11). Further, the air conditioner ECU 14 calculates a voltage to be supplied to the blower drive unit 34 so that the amount of air blown by the blower 56 becomes a necessary amount, and drives the blower drive unit 34 with the voltage (step S12). Furthermore, the air conditioner ECU 14 calculates the position of the mode switching damper 52 or 54 according to the mode set by the operation display unit 20 or the mode forcibly set in step S24, and drives the mode switching damper drive unit 38. Then, the mode switching damper 52 or 54 is switched (step S13).

  The above process is repeated until the condition of air conditioning by the passenger is changed (step S14).

  In the embodiment described above, the necessity of mode switching is determined by one continuation determination time T. However, as shown in the flowchart of FIG. 6, two different continuation determination times T1 and T2 (T1 <T2) are obtained. It may be used to determine whether mode switching is necessary.

  That is, Xrmax ≦ Xr (step S21), and when Xr−Xrmax> ΔX (step S41) when a predetermined humidity difference is ΔX (step S41), there is a high possibility that condensation will occur on the window glass 31. When the time N · Δt during which the state of Xrmax ≦ Xr is continued reaches the short continuation determination time T1 (step S42), the mode switching control is performed so that the air outlets 42 and 46 are opened. (Step S43). Further, when Xrmax ≦ Xr (step S21) and Xr−Xrmax ≦ ΔX (step S41), it is determined that the possibility of condensation on the window glass 31 is low, and the state where Xrmax ≦ Xr is satisfied. When the duration N · Δt reaches the continuation determination time T2 longer than the continuation determination time T1 (step S44), the mode switching control is performed so that the air outlets 42 and 46 are opened (step S44). S43).

  By performing the mode switching control in this way, it is possible to more reliably avoid the condensation of the window glass 31 due to a sudden change in operating conditions and environmental conditions.

It is explanatory drawing of the vehicle carrying the vehicle air conditioner of this embodiment. It is a block diagram of the vehicle air conditioner of this embodiment. It is a process flowchart in the vehicle air conditioner of this embodiment. It is a wet air diagram. It is a detailed flowchart of control temperature calculation in the process flowchart shown in FIG. It is a flowchart of other embodiment of the mode switching process in the process flowchart mode shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle air conditioner 12 ... Vehicle 14 ... Air-conditioner ECU 16 ... Air-conditioner unit 18 ... Engine 20 ... Operation display part 22 ... Outside temperature sensor 24 ... Solar radiation sensor 26 ... Coolant temperature sensor 28 ... Vehicle interior temperature sensor 30 ... Car Indoor humidity sensor 31 ... Window glass 52, 54 ... Mode switching damper 56 ... Blower 58 ... Evaporator 60 ... Heater 66 ... Evaporator outlet temperature detection sensor 68 ... Compressor 70 ... Condenser 72 ... Gas-liquid separator 74 ... Expansion valve

Claims (2)

In a vehicle air conditioner that controls the cooling means and the heating means to control the air conditioning in the passenger compartment,
A window glass vehicle interior surface temperature acquisition means for acquiring the window glass vehicle interior surface temperature;
Window glass dew point vehicle interior absolute humidity obtaining means for obtaining window glass dew point vehicle interior absolute humidity Xrmax with the window glass vehicle interior surface temperature as a dew point;
Vehicle interior absolute humidity acquisition means for acquiring vehicle interior absolute humidity Xr;
Continuation time determining means for determining whether or not the state of Xrmax ≦ Xr continues for a predetermined time or more;
When it is determined that the state of Xrmax ≦ Xr has continued for a predetermined time or more, the outlet switching means for switching to the outlet for blowing air to the window glass,
A vehicle air conditioner comprising: The apparatus of claim 1.
When the predetermined humidity difference between the vehicle interior absolute humidity Xr and the window glass dew point vehicle interior absolute humidity Xrmax is ΔX, the air outlet switching means is in a state where Xr−Xrmax> ΔX continues for the continuation determination time T1 or more. Or, when the state of 0 ≦ Xr−Xrmax ≦ ΔX continues for a continuation determination time T2 (T1> T2) or longer, the vehicle air conditioner is switched to a blowout port that blows out air to the window glass.

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