FR2811617A1 - Air-conditioning system for an automotive vehicle, has a control unit which ensures the minimum overall electrical energy consumption - Google Patents

Abstract

The condenser fan speed regulating device (10) regulates the speed to a continually varying intermediate value, in order to always minimise the total electrical consumption (W) of the air-conditioner. To this end, the correlation data between the total consumption, the control voltage of the condenser fan motor (Vfan) an the different relative parameters of the air-conditioner are previously determined in a laboratory. These data allows obtaining of a statistical regression formula between the voltage (Vfan) and the different parameters, which minimises the total consumption (W). The air-conditioner has a main control unit (10) and a refrigerating circuit (7) having a variable cylinder compressor (5), a condenser (3), a pressure relief valve (6) and an evaporator (2). The condenser is cooled by the condenser fan (8).

Description

i

AIR CONDITIONER FOR VEHICLE

FIELD OF THE INVENTION

  The present invention relates to a vehicle air conditioner having a reduced total power consumption. More particularly, the present invention relates to a vehicle air conditioner that can maintain the total power consumption to about a minimum level by controlling a fan motor.

  of condenser in response to changing conditions.

PRIOR STATE OF THE TECHNIQUE

  A known conventional and conventional type air conditioner for a vehicle is shown in FIG. 1. The refrigerant circuit 107 comprises a compressor 105, a condenser 103, an expander 106 and an evaporator 102. The compressor 105 is driven by a vehicle engine 104 The switching of the motive power transmission from the engine 104 to the compressor 105 is controlled by a clutch control signal CLT. The condenser fan motor 109 cools the heat dissipation condenser 103 by rotating the condenser fan 108. Usually, a radiator 20, in which an engine cooling water circulates, is disposed downstream of the condenser 103 in a direction of rotation. ventilation, so that the condenser 103 and the radiator 20 can be cooled at the same time by the ventilation generated by the condenser fan 108. The evaporator 102, disposed in an air duct 101, cools the air passing through of it. A controller 110 controls the condenser fan motor 109 and the clutch of the compressor 105. A signal Sp from a vehicle speed sensor 113 and a signal Tw from a cooling water temperature sensor of

  motor 114 are presented at the input of the controller 110.

  According to the passenger air conditioning requirements, the controller 110 sends the clutch control signal CLT to the clutch of the compressor 105. Then, based on the vehicle speed signal Sp, the water temperature signal Tw engine cooling and clutch control signal CLT, the controller 110 sends. also a condenser fan motor control signal F to the control means of

  ON / OFF condenser motor 112.

  FIG. 2 is a block diagram of the control of the condenser fan motor 109. In this conventional air conditioner, as their name indicates, the condenser motor ON / OFF control means 112 simply

  run or stop the condenser fan motor 109. That is,

  say that the condenser fan motor 109 is either in a shutdown state or in a full speed rotational state. In other words, the condenser motor ON / OFF control means controls the condenser fan motor 109 neither at any intermediate voltage, nor at any intermediate rotational speed. Usually, the on / off switching of the condenser fan motor 109 is established in synchronization with the clutch control signal CLT. Returning to FIG. 1, when the clutch control signal CLT is active, the condenser fan motor signal F is active, this

  which turns the condenser fan motor at full speed.

  This is normal because when the clutch control signal CLT is active, the compressor is driven and the refrigerant circuit is circulated. Then, the condenser 103 dissipates the heat. That is why the condenser fan motor must be driven in order to cool the condenser 103. On the other hand, when the clutch control signal CLT is OFF, the condenser fan motor signal F is also on OFF, which stops the condenser fan motor. This is normal because when the clutch control signal CLT is OFF, the compressor is not driven and the refrigerant circuit does not operate. Then, the condenser 103 does not dissipate heat. This is why the condenser fan motor does not have to cool the condenser 103. The condenser fan motor 109 in a conventional air conditioner is

ordered according to this logic.

  The maximum total power consumption of this conventional vehicle air conditioner is approximately 2kW, while the power consumption of the condenser fan motor is approximately 100 W. The air conditioner with the condenser fan motor is controlled according to the logic explained above, however, presents

several disadvantages.

  First, this conventional air conditioner does not consider the ambient air temperature when controlling the condenser fan motor. For example, when the ambient temperature is relatively low and the vehicle is traveling at a sufficient speed, the natural ventilation that is generated by the movement of the vehicle itself can sufficiently cool the condenser 103. However, whenever the air conditioner Conventional is turned on, it also turns on the condenser fan motor 109, regardless of the ambient temperature. As a result, under these conditions, the conventional air conditioner is unnecessarily wasting electricity for the fan motor.

condenser 109.

  Secondly, the conventional air conditioner can not run the condenser fan motor 109 at an intermediate speed. For example, when the ambient temperature is relatively low and the vehicle is traveling at a slower speed, the condenser fan can cool the condenser even if it is running at a moderate speed, not at full speed. However, each time the conventional air conditioner is turned on, it also turns on the condenser fan motor 109 to run at full speed, regardless of the speed of the vehicle. As a result, under these conditions, the conventional air conditioner unnecessarily wastes electricity for the condenser fan motor. In addition, it is possible to minimize the total power consumption of the entire air conditioner if the speed of the condenser fan motor is appropriately controlled and continuously varied. This conventional air conditioner does not hold

account of this possibility.

  Thirdly, since the conventional air conditioner controls the condenser fan motor 109 only in an on / off mode, the refrigeration efficiency of the refrigerant circuit 107 often becomes unstable. It causes an oscillation of the temperature of the air blown from the air duct 101. In fact, the variation of the oscillation of the air temperature reaches several degrees and has a period of several seconds on average. This oscillation of temperature is noticeable by the passengers in the vehicle, so

  it creates a feeling of discomfort among passengers.

  In addition, since the condenser fan motor is running at full speed when the condenser fan motor control signal F is active, it also causes a large mechanical noise. In addition, the full speed rotation of the engine of

  Condenser fan affects its reliability and service life.

SUMMARY OF THE INVENTION

  The object of the present invention is to provide a time during which the condenser fan motor is rotated at an intermediate speed. In addition, the air conditioner according to the present invention calculates the intermediate speed of the condenser fan motor so as to minimize the total power consumption of the entire air conditioner. The functional form or the coefficients of the equation used for this calculation are previously determined in the laboratory. In fact, it is possible to find some statistical correlation between the total power consumption of the air conditioner and various parameters relating to the air conditioner. Examination of these statistical correlation data suggests that there is an intermediate speed of the condenser fan motor, at which the total power consumption of the entire air conditioner is minimized. Thus, a kind of regression relationship between the intermediate speed of the condenser fan motor and various other parameters relating to the air conditioner can be previously determined in the laboratory. By using this regression relationship, it becomes possible to calculate the intermediate speed of the condenser fan motor which minimizes the total power consumption of the entire air conditioner. In this way, it becomes possible to economize appropriately the total electricity consumption of

the entire air conditioner.

BRIEF DESCRIPTION OF THE FIGURES

  Other objects, features and advantages of this invention

  will be better understood by reading the following description of modes

  preferred embodiment, with reference to the drawings in which: Figure 1 is a schematic view showing the configuration of a conventional air conditioner for a vehicle; Figure 2 is a control block diagram of the conditioner shown in Figure 1; Figure 3 is a schematic view showing the configuration of a vehicle air conditioner according to a first embodiment of the invention; Fig. 4 is a block diagram of control of the apparatus shown in Fig. 3; Figure 5 is a block diagram explaining how the candidate value Vl is derived; Fig. 6 is a schematic illustration showing the configuration of a vehicle air conditioner according to the second embodiment of the present invention; Fig. 7 is a block diagram of control of the apparatus shown in Fig. 6; and FIG. 8 is a variant of the control functional diagram

  of the apparatus shown in FIG.

  DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

  An air conditioner for a vehicle according to a first embodiment of the present invention is shown in FIG. 3. The refrigerant circuit 7 of the air conditioner comprises a variable displacement compressor 5, a condenser 3, an expander 6 and an evaporator 2. The compressor variable displacement 5 is driven by the engine 4 of the vehicle. The power of the variable displacement compressor 5 is controlled by a power control signal Ic. A condenser fan motor 9 cools the heat dissipation condenser 3 by rotating a condenser fan 8. Usually, a radiator 20, in which an engine cooling water circulates, is disposed downstream of the condenser 3 in a direction of ventilation, so that the condenser 3 and the radiator 20 can be cooled at the same time by the ventilation generated by the condenser fan 8. The evaporator 2, disposed in an air duct 1, cools the air passing through of it. A main control device 10 controls the speed of rotation of the condenser fan motor 9 and the power of the

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  variable-displacement compressor 5. A signal Sp from a vehicle speed sensor 12, a signal All from an ambient temperature sensor 13 and a signal Tw from an engine cooling water temperature sensor 14 are presented at the input of the main controller 10. On the basis of various parameters, including the three signals above, the main controller 10 sends a power control signal Ic to the variable displacement compressor 5 and a condenser fan motor control signal Vfan to the voltage control means 11 of the condenser fan motor 9. The main controller 10 determines the condenser fan motor control signal Vfan with reference to the control signal. power setting Ic, which is calculated by the main control device 10 itself, at the vehicle speed signal Sp and the temperature signal of the water of re engine cooling Tw. The Vfan condenser fan motor control voltage is

  selected from the values VO, Vi and V2, according to Table 1.

  This table is a table for selecting the control voltage Vfan of the condenser fan motor of the apparatus shown in FIG. 3 and FIG. 6; Two candidate values VO and V2 are constants, VO corresponding to a stopping state of the condenser fan motor 9, V2 corresponding to the state of rotation at full speed of the condenser fan motor 9. The candidate value V1 is the intermediate value continuously varies and it constitutes the main advantage of the present invention. Table 1 below illustrates a general specification required by the vehicle to operate the

  condenser fan motor 9 air conditioner.

  Table 1. Vfan replacement table from the three candidate values VO, VI, V2 depending on the conditions

From Sp, Tw and Ic.

  Slow. Vehicle speed - Fast Sp <B1 B1 _ <Sp <B2 B2_-Sp Ic <A1 Al <lc Ic <A1 A1 <c Ic <A1 A1 <lc t Cold Tw <C1 VO VI Water temperature VO V1 VO VO C1 <Tw <: C2 motor V2 V2 Hot C2 <; Tw V2 V2 V2 V2 Referring to Table 1, the right side of the table indicates the Vfan selection mode at a fast vehicle speed and the left side of the table indicates the Vfan selection mode at a slow vehicle speed. In the table, B i and B2 are constants. For example, Bi = 10 km / h and B2 = 80 km / h. Referring to Table 1, the upper side of the table indicates the selection mode of Vfan at a cooler engine coolant temperature, and the bottom side of the table indicates the Vfan selection mode at a temperature of the engine. warmer engine cooling water. In the table, C1 and C2 are constants. By

  for example, C l = 95 degrees Celsius and C2 = 110 degrees Celsius.

  Moreover, in the table, AI is also a constant. A state in which Ic <A1 suggests a state in which the power of the variable displacement compressor is low, i.e., a state in which the refrigerant circuit 7 is not operating normally. On the other hand, a state in which Al <Ic suggests a state in which the

  power of the variable displacement compressor is important, that is,

  say a state in which the refrigerant circuit 7 is normally in operation. When the vehicle speed is slow (Sp <B1) and the temperature of the engine cooling water is high (Cl <Tw <C2 or C2 <Tw), the radiator 20 must be cooled; therefore, the condenser fan motor 9 will be driven at full speed (Vfan = V2). Here the temperature of the cooling water

  engine rarely rises to an excessively high value (C2 <Tw).

  When the vehicle speed is slow (Sp <B1) and the temperature of the engine cooling water is low (Tw <Cl), the radiator does not have to be cooled; therefore, the condenser fan motor 9 is either stopped (Vfan = V0) or driven at an intermediate speed (Vfan = Vi). VI is selected as the value of Vfan (Vfan = Vi) when the refrigeration circuit 7 is normally in

operation (Al <Ic).

  When the vehicle speed is equal to an intermediate value (B1 <Sp <B2), V0 or V1 is selected until the temperature of the engine cooling water reaches C2. This is due to the fact

  the natural ventilation generated by the movement of the vehicle itself

  This is in addition to the ventilation generated by the condenser fan.

  When the vehicle is traveling at a high speed (B2 <Sp), Vfan is equal to V0 (Vfan = V0) only until the temperature of the engine cooling water has reached C2. In this condition, since

  the natural ventilation generated by the movement of the vehicle itself

  even with sufficient force, the condenser 3 and the radiator 20 can be sufficiently cooled, even if the fan motor of

condenser is not driven.

  FIG. 4 represents a control functional diagram corresponding to an air conditioner shown in FIG. 3. In a 10 box represented in the center of the diagram, the candidate value VI having an intermediate value is calculated as a function of the temperature.

  Everything ambient and vehicle speed Sp.

  As mentioned above, the candidate value VI takes a continuously varying intermediate value, which is the main advantage of the present invention. The function f shown in FIG. 4, which makes it possible to calculate the candidate value Vi for the condenser fan motor control signal which minimizes the total electrical consumption of the whole of the

  air conditioner, can be obtained in the following manner.

  On the left side of Figure 5 are various parameters that directly affect the total power consumption of the entire air conditioner. The temperature of the air at the outlet of the evaporator Teout (whose detection requires a temperature sensor disposed downstream of the evaporator), the ambient temperature All, the internal temperature Tin (that is to say the air temperature inside the vehicle interior), the state of the intake door register INT (to be described later), the blower voltage BLV (which will also be described later), the signal the power control Ic and the discharge pressure Pd of the variable displacement compressor (the detection of which requires a pressure sensor) influence the total power consumption of the variable compressor Wcomp. The blower voltage BLV, the condenser fan motor voltage Vfan, the battery voltage VB and the electrical heating voltage Vh influence the total power consumption of the electrical devices Welc. The actual consumption of electrical energy is given by Welc multiplied by the alternator / regulator efficiency i1. The total power consumption W of the entire air conditioner is the sum of Wcomp and rilWelc. The vehicle speed Sp also influences the total power consumption W, but indirectly. All the parameters listed above, including the vehicle speed Sp, form the parameters relating to the air conditioner. In this specification, some of them, other than the condenser fan motor control voltage Vi, are selected and called "explanatory variables". The condenser fan motor control voltage Vi is referred to as the "objective variable" in this specification. In the first embodiment of the present invention, shown in FIGS. 3 and 4, the ambient temperature All and the vehicle speed Sp are used as explanatory variables. When in the laboratory, these explanatory variables are set to various values and the candidate value Vi is varied, the total electrical consumption W also varies. Parameters other than the selected explanatory variables are assumed to have a low correlation with the total power consumption W and therefore are not taken into account for control of the condenser fan motor. A curve representing the variation of W with respect to the variation of VI usually has a minimum Wmin. By repeating the measurement of the total electrical consumption W, of Vi and the temporarily fixed explanatory variables Tout and Sp, one can obtain a set of correlation data which always minimizes the total electrical consumption W. Data (V1l 1, Toutl, Spl) Given (V12, Tout2, Sp2) Given (V13, Tout3, Sp3) Given (Vln, Toutn, Spn) We can then derive a type of regression relation between the objective variable Vi and the explanatory variables Tout, Sp, which always minimizes total power consumption, by processing the above dataset by a statistical analysis. For example, we can deduce the following equation: Vl = f (All, Sp) = aTout + bSp + Ki (1) where a, b and Ki are regression coefficients and a regression constant. This is the function for calculating the candidate value Vl. This "regression function" can take a form

  functional other than a linear function.

  Therefore, when the selected explanatory variables are given, using the "regression formula" such as equation (1), an appropriate candidate value Vi can be calculated by which the total power consumption W can always be minimized. Moreover, since the candidate value Vl varies continuously and not by on / off stages, the refrigeration efficiency becomes stable, so that the temperature of the air blown from the air duct 1 does not oscillate. perceptible way. And since the full-speed rotation time of the condenser fan motor is reduced, the noise caused by the condenser fan motor is also reduced. For the same reason, the life of the engine of

  condenser fan is extended.

  An air conditioner for a vehicle according to the second embodiment of the present invention is shown in FIG. 6. In this figure, a fan blower 25 and a motor 26 which drives the fan blower 25 are arranged upstream of an evaporator 2. in an air duct 1. The motor 26 is controlled by a voltage control device 27 of the blower. The fan voltage control device 27 is controlled by a control signal BLV output from a main controller 10. Above the fan blower 25 is an outside air intake 21 and an air intake. 22. The angular position of a door damper 23 determines the ratio between the air introduced by the outside air intake 21 and the air introduced by the indoor air inlet 22. The angular position of the register 23 is controlled by an intake door register actuator 24. The inlet door damper actuator 24 is controlled by a signal INT emitted by the main control device 10. An air temperature sensor The evaporator outlet 28 is disposed downstream of the evaporator 2 in the air duct 1. A signal Teout from the sensor 28 is presented at the input of the main control device 10. An indoor temperature sensor 29 is disposed at i inside the passenger compartment of the vehicle. A signal Tin from the indoor temperature sensor 29 is presented to the input of the main control device 10. The rest of the structure of the apparatus shown in Fig. 6 is identical to that of the apparatus

shown in Figure 3.

  In comparison with the first embodiment, the air conditioner according to the second embodiment uses more explanatory variables to calculate the candidate value V1. With reference to FIG. 7, the objective variable, that is to say the candidate value V1 in the second embodiment, is calculated using a function having 5 explanatory variables: Ic, Tein, All, BLV and Sp. Here, Tein is an estimated value of the air temperature upstream of the evaporator 2, given by Tein = ciTout + (lo) Tin where the mixing ratio ct is calculated by a function f of the signal of

  door register actuator control INT.

  c = f (INT) When in the laboratory, the selected explanatory variables are set at different values and the candidate value VI is varied, the total power consumption W also varies. The curve representing the variation of W with respect to the variation of VI usually has a minimum Wmin. By repeating the measurement of the total power consumption W, of V1 and the temporarily fixed explanatory variables Ic, Tein, Tout, BLV and Sp, a set of correlation data can be obtained which always minimizes the total power consumption W. Data (V1l1 , Icl, Teinl, Toutl, BLV1, Spl) Data (V12, Ic2, Tein2, Tout2, BLV2, Sp2) Data (V13, Ic3, Tein3, Tout3, BLV3, Sp3) Data (Vln, Icn, Teinn, Toutn, BLVn , Spn) We can then deduce a type of regression relation between the objective variable VI and the explanatory variables Ic, Tein, Tout, BLV and Sp, which always minimizes the total electricity consumption, by treating the data set above with a statistical analysis. By

  For example, we can deduce the following equation.

  Vi = f (Ic, Tein, All, BLV, Sp) = pIc + qTein + rAll + sBLV + tSp + K2 (2) op, q, r, s, t and K2 are regression coefficients and a regression constant . This is the function to calculate the value

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  candidate V1. This "regression function" can take a form

  functional other than a linear function.

  As a result, when the selected explanatory variables are given, using the "regression formula" such as equation (2), an appropriate candidate value V1 can be calculated by which the total power consumption W can always be minimized. Moreover, since the candidate value V1 varies continuously and not by on / off steps, the refrigeration efficiency becomes stable, so that the temperature of the air blown from the air duct does not oscillate. perceptible. And since the full-speed rotation time of the condenser fan motor is reduced, the noise caused by the condenser fan motor can also be reduced. For the same reason, the life of the engine

  condenser fan can be extended.

  To calculate the candidate value V1, other parameters relating to the air conditioner, such as a measured value, that is to say a value detected by a certain sensor, or control signals transmitted by the main control device, may be used as

explanatory variables.

  Finally, FIG. 8 is a control block diagram

  representing a variant of the calculation mode of the candidate value V1.

  So far, V1 has been recalculated using an instantaneous value of the explanatory variables at each computation cycle, as can be seen from equations (1) and (2). In the block diagram shown in Fig. 8, a regression relationship, which always maximizes the reduction of the total power consumption of the air conditioner in response to variations of V1, BLV, Teout, and Tein, is derived. In this variant, the variation AV1 of V1 is calculated from a summation of three functions independent of the variations of

  three parameters, that is ABLV, ATeout and ATein.

  In this variant, the objective variable is AV1 and the explanatory variables are ABLV, ATeout and ATein. As in the first embodiment, when in the laboratory the selected explanatory variables are set at different values and the objective variable AV1 is varied, the reduction -AW of the total electrical consumption WV also. The curve representing the variation of -AW with respect to the variation of AV1I usually has a negative maximum -AWmax. By repeating the measurement of the reduction -AW of the total power consumption W, of AV1 and the temporarily fixed explanatory variables ABLV, ATeout and ATein, a set of correlation data can be obtained which always maximizes the reduction of the total power consumption. Data (AV 11, ABLV1, ATeoutl, ATeinl) Data (AV12, ABLV2, ATeout2, ATein2) Data (AVl3, ABLV3, ATeout3, ATein3) Data (AVln, ABLVn, ATeoutn, ATeinn) One can then deduce a type of relation of regression between the objective variable AVI and the explanatory variables ABLV, ATeout and ATein, which always maximizes the reduction of the total power consumption W, by treating the data set above with a

  statistical analysis. For example, one can derive the following equation.

  In this variant, the correlations between AW and ABLV, AW and ATeout and

  AW and ATein are supposed to be independent of each other.

  AVI = VI - Vi '= F (ABLV, ATeout, ATein) = Vb + Vo + Vi (3) Vb = fb (ABLV) = k ABLV + K3 (4) Vo = fo (ATeout) = lATeout + K4 (5) Vi = fi (ATein) = mATein + K5 (6) ok, 1, m and K3, K4, K5 are regression coefficients and regression constants. These are functions intended to calculate the next candidate value Vl = Vl '+ AVl. These "regression functions"

  can take a functional form other than a linear function.

  Therefore, when the selected explanatory variables are given, using the "regression formulas" such as equations (4), (5) and (6), a suitable next candidate value Vl can be calculated from which the consumption total electrical power can always be reduced by a maximum amount. Moreover, since the candidate value V1 varies continuously and not by on / off stages, the refrigeration efficiency becomes stable, so that the temperature of the air blown from the air duct does not oscillate.

perceptible way.

  Although the present invention has been described in detail with reference to preferred embodiments, the invention is not limited thereto. It will be understood by those skilled in the art that variations and modifications may be made within the scope of this invention.

Claims (4)

  A vehicle air conditioner having a main control device (10) at the input of which a signal (All) of an ambient temperature sensor (13) and a signal (Sp) of a vehicle speed sensor (12). ) are presented, and a refrigerant circuit (7) comprising a variable displacement compressor (5), a condenser (3) in front of which is disposed a condenser fan (8), a pressure regulator (6) and an evaporator (2) disposed in an air duct (1), characterized in that; said main controller (10) controls the motor (9) of said condenser fan (8) in response to instantaneous values of ambient temperature (All) and vehicle speed (Sp), using a regression relationship between a a condenser fan motor control signal (Vfan), an ambient temperature (All) and a vehicle speed (Sp), wherein said regression relationship is derived from statistical correlation data between the total power consumption (W) of said air conditioner, condenser fan motor control signal (Vfan), ambient temperature (All) and vehicle speed (Sp) previously determined in the laboratory so as to always minimize the total electrical consumption (W) of said air conditioner. A vehicle air conditioner having a main control device (10) at the input of which a signal (All) from an ambient temperature sensor (13) and a signal (Sp) from a vehicle speed sensor (12). ) are presented, and from which a compressor power control signal (Ic), a fan voltage control signal (BLV) and an input gate register actuator signal (INT) are transmitted, and a refrigerant circuit (7) comprising a variable displacement compressor (5), a condenser (3) in front of which is disposed a condenser fan (8), an expander (6), an evaporator (2) arranged in a duct an air blower (1), a blower disposed upstream of said evaporator (2) in said air duct (1) and an intake door register (23) upstream of said blower in said air duct (1); ), characterized in that said main control device (10) controls said condenser fan motor (9) in accordance with instantaneous values of a group of parameters relating to said air conditioner, comprising a compressor power adjustment signal (Ic), an air temperature at the evaporator inlet, estimated from said output signal; intake gate damper actuator (INT), ambient temperature (All), blower control voltage (BLV) and vehicle speed (Sp), using a regression relationship between the motor control signal of a condenser fan (Vfan) and said parameter group (Ic, INT, Tout, BLV and Sp), wherein said regression relation is derived from statistical correlation data between the total power consumption (W) of said air conditioner, the signal for controlling the condenser fan motor (Vfan) and said group of parameters (Ic, INT, Tout, BLV and Sp) previously determined in the laboratory, so as to always   minimize the total power consumption (W) of said air conditioner.   A vehicle air conditioner having a main control device (10) and a refrigerant circuit (7) comprising a variable displacement compressor (5), a condenser (3) in front of which is disposed a condenser fan (8), a expander (6), an evaporator (2) disposed in an air duct (1), a temperature sensor (29) disposed downstream of said evaporator (2), a blower disposed upstream of said evaporator (2) in said duct air intake (1) and an intake port register (23), characterized in that; said main controller (10) controls said condenser fan motor (9) in response to changes in values of a group of parameters relating to said air conditioner, including a fan control signal, an air temperature to the evaporator inlet estimated from the state of said inlet gate register (23), and an evaporator outlet air temperature (Teout) detected by said sensor (28), using a regression relationship between the variation of the condenser fan motor control signal (Vfan) and variations of said parameter group, wherein said regression relationship is derived from statistical correlation data between the variation in power consumption total (W) of said air conditioner, the variation of the condenser fan motor control signal (Vfan) and variations of said predetermined group of parameters determined in the laboratory , so as to always maximize a reduction in   total power consumption (W) of said air conditioner.   A vehicle air conditioner having a main controller (10) at whose input sensor signals are presented (Sp, Tout) and from which control signals are transmitted (Ic, BLV, INT), and a refrigerant circuit (7) comprising a variable displacement compressor (5), a condenser (3) in front of which is disposed a condenser fan (8), an expander (6), an evaporator (2) arranged in a duct air (1) and a blower disposed upstream of said evaporator (2), characterized in that said main controller (10) controls said condenser fan motor (9) in response to instantaneous values of a group of parameters relating to said air conditioner, comprising signals (Sp, Tout) detected by said sensors (12, 13) and control signals (Ic, BLV, INT) transmitted from said main controller (10), using a relation of regression between the ve motor control signal condenser ntilator (Vfan) and said parameter group, wherein said regression relationship is derived from statistical correlation data between the total power consumption (W) of said air conditioner, the condenser fan motor control signal (Vfan), and said group of parameters previously determined in the laboratory, so as always to minimize the total power consumption (W) of said air conditioner.