FR2801008A1 - AIR CONDITIONING SYSTEM FOR VEHICLES - Google Patents

Abstract

The invention relates to an air conditioning system (1) for vehicles. The air conditioning system comprises a variable displacement compressor (12), an air duct (2) equipped with a fan (7), an evaporator (8) , a heater (9), means for determining humidity used to detect humidity in the passenger compartment, means for controlling the efficiency of the evaporator (8), means for controlling the temperature in the passenger compartment adjusting the efficiency of the heater (9), and means for adjusting the feeling of heat capable of arbitrarily adjusting a target value of a feeling of heat index corresponding to the feeling of heat. The temperature control means in the passenger compartment vary a temperature to be monitored as a function of various information, in particular the humidity detected or estimated in the passenger compartment.

Description

1i 2801008

  AIR CONDITIONING SYSTEM FOR VEHICLES

  The present invention relates to an air conditioning system for vehicles and more specifically, an air conditioning system for vehicles making it possible to obtain both an optimization of a pleasant feeling of warmth for a person in a vehicle and reduction of electrical consumption. The purpose of air conditioning in vehicles is to provide a pleasant feeling of warmth by taking into account a wish (of an adjustment) of a person in the vehicle. Among the factors influencing the pleasant feeling of heat, one can quote for example (1) the quantity of heat radiation (quantity of sunshine, temperature of the walls influenced by the temperature of the outside air = temperature of the glass of the windows) , (2) air circulation in a passenger compartment influenced by the amount of air delivered by a fan, (3) the temperature of the interior air in a passenger compartment, (4) humidity in the passenger compartment, (5) the quantity of clothing worn by the person in the vehicle and (6) the metabolic quantity of said person. Although it is in principle possible for an air conditioning system to create a pleasant warm feeling environment by detecting, estimating and controlling these factors, there is no known system that takes all of these factors into account, and in conventional systems, especially if the humidity varies,

  the pleasant feeling of warmth can be reduced.

  In addition, saving energy is a social imperative and in the technology for designing an air conditioning system for vehicles, it is not uncommon. The best energy saving effect in an air conditioning system for vehicles is obtained by optimizing the efficiency control of an evaporator in a cooling system. In conventional technology, the temperature of an evaporator in a cooling system (almost proportional to the efficiency of the evaporator) was controlled at a lower limit temperature that did not cause icing, and a control temperature required for air conditioning was obtained by controlling the efficiency of a heater arranged in a position downstream of the evaporator in an air duct. However, recently the power consumption of a cooling system has been

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  decreased by reducing the efficiency of the heater and running the evaporator at a higher temperature (by reducing the efficiency of the evaporator). However, in this type of control, since the amount of dehumidification due to the evaporator varies, even if the temperature of the passenger compartment does not change, the humidity of the air expelled from the duct can vary and this can vary l in

  the interior and reduce the pleasant feeling of warmth.

  As a conventional control system for air conditioning taking into account a pleasant feeling of warmth, there is known an air conditioning system for vehicles in which the temperature in a passenger compartment to be monitored is determined taking into account the amount of sunshine, the outside air temperature, the amount of air blown by a fan, the value required by a person in the vehicle, etc., so as to obtain a pleasant feeling of heat required (see for example JP-A- 11-1112, JP-A-11-1113). However, in such a system, since humidity is not taken into account, when the humidity in a passenger compartment

  varies, the pleasant feeling of warmth can be reduced.

  Furthermore, as a conventional control system for air conditioning taking energy saving into account, there is known an air conditioning system for vehicles in which the movement of a compressor is controlled taking into account the temperature of the outside air. , etc., so as to control the temperature on the outlet side of an evaporator to achieve a minimum power consumption of the compressor in a condition where the glass does not fog up (see for example JP-A-11-115447). However, in such a system, since a command does not take into account the factors described above (1), (5) and (6), or the factors described above (2) and (4), the pleasant feeling of warmth can be

3 o decreased.

  If we just combine the conventional control system described above for air conditioning taking into account a pleasant feeling of warmth and the conventional control system described above for air conditioning taking into account energy saving, although this solution seems to produce both the pleasant feeling of warmth and the energy saving to some extent, there may be a decrease in the pleasant

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  feeling of heat due to a change in humidity in the passenger compartment caused by a change in the temperature of the evaporator, etc., and therefore such a combined system would not be sufficient to serve as a control system for a pleasant feeling of warmth taking into account humidity. An object of the present invention is to provide an air conditioning system for vehicles which can reduce the electrical consumption of a compressor by optimizing the control of the dehumidification efficiency of an evaporator, and which can also control a pleasant feeling of heat, more optimally

  by air conditioning, taking into account the humidity in a passenger compartment.

  This object is achieved by the air conditioning system for vehicles of the present invention. The air conditioning system for vehicles according to the invention comprises a) a variable displacement compressor; b) an air duct fitted with a fan and having air outlet openings opening towards a passenger compartment; c) an evaporator arranged in the air duct, the evaporator being connected to the compressor via a refrigerant circuit and ensuring the cooling and dehumidification of the air passing through the air duct; d) a heater disposed in the air duct in a position downstream of the evaporator, the heater being able to adjust its air heating efficiency; e) means for determining the humidity by detecting the humidity of the passenger compartment or by estimating a state variable determining the humidity in the passenger compartment; f) means for controlling the efficiency of the evaporator by controlling the displacement of the compressor and by adjusting the cooling and dehumidification efficiency of the evaporator; g) means for controlling the temperature of the passenger compartment by adjusting the efficiency of the heater; and h) means for adjusting the sensation of heat capable of arbitrarily adjusting a target value of a heat sensation index which corresponds to the sensation of heat. The cabin temperature control means vary the temperature of the cabin to be monitored as a function of various information, in particular the humidity of the cabin detected or estimated.

  by means of determining humidity.

  In an air conditioning system, the humidity determination means can estimate the dew point temperature in

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  the passenger compartment or a state variable correlated thereto (for example, absolute humidity) as a factor for determining the humidity in the passenger compartment and the passenger compartment temperature control means may have a calculation factor intended to reduce the cabin temperature to be monitored as a function of the rise in the estimated dew point temperature or of the state variable correlated thereto. The dew point temperature can be estimated as a function of a state variable correlated with the cooling / dehumidifying efficiency of the evaporator (for example, the temperature of the air leaving the evaporator, the temperature between the fins of the evaporator, the temperature of the fins, or a value estimated or detected as a coolant temperature at the inlet of the evaporator). The cabin temperature control means can determine the cabin temperature to be monitored as a function of the ambient temperature in the cabin and

  of a determined relative humidity.

  Alternatively, the air conditioning system may include a humidity sensor, the humidity determining means being able to determine the humidity in the passenger compartment in response to a signal from the humidity sensor, and the temperature control means. of the cockpit which may have a calculation factor intended to reduce the cockpit temperature to be monitored according to an elevation of

humidity determined.

  In addition, in the air conditioning system, the displacement of the compressor can be adjusted so that a relative humidity in the passenger compartment is controlled, for example, to remain between 50 and 80%. Although the means intended to control the displacement of the compressor are not particularly limited, they comprise for example means intended to control a discontinuous operation of the compressor on / off system. Alternatively, the displacement of the compressor can be

  adjusted for arbitrary displacement in response to an external signal.

  In the vehicle air conditioning system according to the present invention, controlling the operation of the compressor so that the evaporator is activated in an optimal state within the range in which no icing of the evaporator occurs. product, i.e. in such a way that the yield of

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  dehumidification of the evaporator is optimally controlled, the power consumption of the compressor can be reduced. At the same time, by controlling the air conditioning taking humidity into account, more concretely, by controlling the temperature in the passenger compartment taking humidity into account, we can optimize the pleasant feeling of warmth. Consequently, both the reduction in power consumption and the pleasant feeling of

optimal heat.

  Other features and advantages of the present invention

  will be perceived on reading the detailed description below of the modes

  of preferred embodiments of the present invention, made with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of an air conditioning system according to a first embodiment of the present invention; Figure 2 is a block diagram showing an example of the control in the air conditioning system illustrated in Figure 1; Figure 3 is a graph showing an example of the temperature and humidity properties shown by the control illustrated in Figure 2; and Figure 4 is a block diagram showing an example of an air conditioning system control from a second

  embodiment of the present invention.

  Figure 1 shows a schematic structure of an air conditioning system according to a first embodiment of the present invention and Figure 2 shows an example of the control in a main controller illustrated in Figure 1. Figure 1 illustrates

  mainly the mechanical part of an air conditioner 1 for a vehicle.

  An air path 2a is formed in an air duct 2, and an interior air introduction port 3 and an exterior air introduction port 4 are open at an inlet position of the air duct. air 2. A switchable register 5 controls a ratio between the quantity of air sucked in through the orifice 3 and that sucked in through the orifice 4. The sucked air is sent into the air duct 2 by a fan 7 driven by a motor 6. The amount of air sent by the fan 7 is adjusted by controlling the

motor 6.

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  An evaporator 8 acts as a cooler in a position downstream of the fan 7, and a hot water heater 9 acts as a heater in a position downstream of the latter. Engine cooling water 10a supplied from an engine 10, which is a high temperature liquid, is circulated in the hot water heater 9 to serve as a heat source, and the air

  suction is heated by the hot water heater 9.

  Refrigerant circulating in a refrigerant circuit 11 is supplied to the evaporator 8. The refrigerant is compressed by a variable displacement compressor 12, condensed by a condenser 13, sent to the evaporator 8 via a reservoir 14 and a pressure reducer 15 and sucked into the compressor 12 from the evaporator 8. During the operation of the compressor 12 in this embodiment, the latter is always activated during the operation of the air conditioning by means of the controller command.

clutch 16.

  An air mixture damper 17 is placed in a position immediately downstream of the hot water heater 9. The ratio between the quantity of air passing through the heater 9 and that which bypasses it is controlled by adjusting the degree of opening of the air mixture register 17 activated by an air mixture register actuator 18. The air conditioning temperature is sent into the passenger compartment through respective air outlet ports 19, 20 and 21 - for example, an air outlet in DEF 19 mode (demister), an air outlet in WIND 20 mode (ventilation) and an air outlet in FOOT 21 mode (floor heating). Respective registers 22, 23 and 24 are placed to control the opening and closing of the

  respective air outlet ports 19, 20 and 21.

  A fan voltage controller 25 for controlling the voltage (the speed of rotation) applied to the fan motor 6, the air mixture damper actuator 18 and the displacement variation mechanism of the compressor 12 are controlled on the base of signals sent by a main controller 26. The main controller 26 respectively receives signals from a heat sensation control device 27 capable of controlling the desired temperature in a vehicle and a desired heat sensation, a signal of

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  indoor air temperature detected by an indoor air temperature sensor 28, a signal of an amount of sunshine detected by a sunshine sensor 29, an outdoor air temperature signal detected by a temperature sensor d outside air 30 and an air temperature signal having passed through the evaporator 8 detected by an air temperature sensor leaving the evaporator 31. Although a humidity sensor 32 intended to detect the humidity in the passenger compartment is illustrated in FIG. 1, this sensor relates to a second embodiment described later and a signal of the humidity detected by

  this sensor 32 is presented to the main controller 26.

  The air conditioning according to the invention is controlled in the

  main controller 26, for example as shown in FIG. 2.

  In this embodiment, the humidity in the passenger compartment is estimated from the temperature of the air leaving the evaporator, the pleasant sensation of heat due to the air conditioning taking into account the humidity in the interior can be optimized, and you can also get

  energy saving for the compressor.

  The method for estimating the humidity in the passenger compartment will now be described. The humidity in the passenger compartment can be expressed by a dew point temperature. In addition, since the air introduced from the outside air, or the air drawn from the inside air, is condensed in humidity at the evaporator 8 in the air duct 2, the temperature dew point of the air (or its absolute humidity) is determined by the temperature of the air leaving the evaporator (the dew point temperature is almost equal to the temperature of the air leaving of the evaporator). Since the humidification due to the human body is applied, but a higher humidification is not applied to the air after the outlet of the evaporator, the air in the passenger compartment is maintained in a temperature state of dew point at the outlet of the evaporator (or absolute humidity). This is why the humidity in the passenger compartment can be estimated from the air temperature at the

outlet of the evaporator.

  Furthermore, as we have seen previously, among the factors influencing the pleasant feeling of warmth of a person in a vehicle, one can cite (1) the amount of heat radiation (amount of sunshine, wall temperature influenced by the

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  outside air temperature = window glass temperature), (2) air circulation in a passenger compartment influenced by the amount of air supplied by the fan, (3) the temperature of the indoor air in a passenger compartment, (4) the humidity in the passenger compartment, (5) the quantity of clothing worn by the person in the vehicle and (6) the metabolic quantity of the person in the vehicle. As a standard index for indicating a person's feeling of warmth, we know the CMP value (expected average choice value). In ISO 7730, this CMP is defined by

the following way.

CMP: +3 +2 +1 0 -1 -2 -3

  Sensation: burning hot lukewarm neutral cool cold icy heat In the present invention, the pleasant sensation of heat is optimized by an air conditioning taking particular account of the humidity in the vehicle, which was not taken into account in

conventional technology.

  In this embodiment, as shown in FIG. 2, in the main controller 26, a signal 41 of desired heat sensation TP, adjusted by a heat sensation control device 27, a signal 42 of outside air temperature AMB detected by the outdoor air temperature sensor 30, a sunshine amount signal 43 RAD detected by the sunshine sensor 29, a fan voltage signal BLV and a desired air temperature signal at the outlet of the TV evaporator are presented to the means for calculating the desired temperature in the passenger compartment 44 serving as

  means for determining the desired temperature Tset in the passenger compartment.

  Thanks to these means 44, the desired temperature in the passenger compartment Tset corresponding to a controlled feeling of heat is estimated by calculation using the following equation: Tset = f (BLV, AMB, RAD, TP, TV) In particular, taking into account the desired temperature of the air leaving the TV evaporator constitutes an element which has not been used

in the conventional process.

  The desired temperature of the air leaving the evaporator TV is calculated by means of calculating the desired temperature of the air leaving the evaporator 45 as a function of a set mode 46. When the mode is set in demisting mode, TV is calculated as follows:

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  TV = f (AMB, BLV) When the mode is set in comfort mode, TV is calculated as follows: TV = f (Tset, RH) o AMB is the outside air temperature as above and RH is the relative humidity desired in the passenger compartment (a fixed value). The desired temperature of the outlet air Toc is calculated by means of calculating the desired temperature of the outlet air 47, and these means respectively receive the desired temperature signals in the passenger compartment Tset calculated by the means of calculating desired temperature in the passenger compartment 44, outside air temperature AMB and amount of sunshine RAD, as well as a signal 48 of temperature in the passenger compartment TR detected by the air temperature sensor

interior 28.

  Toc = kp 1 (Tset - TR) + f (AMB, RAD, Tset)

where kp 1 is a coefficient.

  From the result of the calculation of the desired outlet air temperature described above, the fan voltage BLV can be calculated in the following manner by means of voltage calculation of

fan 49.

  BLV = f (Toc) A fan voltage controller 25 is controlled as a function

  of the signal from the fan voltage calculation means 49.

  The degree of opening AMD of the air mixture register 17 is calculated as follows by means of calculating the degree

  opening the air mixing damper 50.

  AMD = f (Toc, Te, TW) o Te is given by a signal 51 of the air temperature at the outlet of the evaporator detected by the air temperature sensor at the outlet of the evaporator 31 , and o TW is a water temperature at the inlet of the heater 9 (TW is set to a fixed value). The air mixture damper actuator 18 is controlled according to the signal from the

  means for calculating the degree of opening of the air mixture register 50.

  In this embodiment, the displacement of the compressor 12 is controlled by a compressor suction pressure controller 52, and the demand signal (suction pressure: Ps) is calculated in the following manner by means of calculation of pressure

compressor suction 53.

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  Ps = P + In P = kp2 (TV- Te) In = In -1 + kp2. K1 (TV - Te) o P represents a proportional term, kp2 is a coefficient and K1 is a constant. Indeed, (TV - Te) is considered as a state variable associated with a humidity, and the operating condition (displacement) of the compressor 12 is optimally controlled, so that the operation of the evaporator 8 is optimized in the range in which the icing of the evaporator 8 does not occur, this

  which saves energy from compressor 12.

  FIG. 3 illustrates an example of the operation associated with this command. The example shown in FIG. 3 relates, for example, to a situation where the outside air temperature is 20 ° C., with a minimum quantity of air ventilation and in night condition, and FIG. 3 is presented under the form of a graph showing the relationship between temperature and absolute humidity to obtain a pleasant feeling of warmth. In Figure 3, the ordinate axis indicates an absolute humidity (kg / kg) and the abscissa axis indicates a cabin temperature (C). The thick line rising to the right, located in the central part of the figure, illustrates the saturation curve of relative humidity RH = 100%. The group of curves designated RH = 80%, RH = 65% and RH = 50%, which are represented below the thick line mentioned above, illustrates the respective relative humidity curves corresponding to relative humidities of 80%, 65% and 50%, which are represented simply by contracting the saturation curve in a direction from the ordinate axis to respective contraction scales. In FIG. 3, the group of straight lines rising to the left illustrates control lines for "comfort lines" determined by the aforementioned conventional technology and by the present invention, for various values of adjustment of the desired sensation of heat. TP (from TP = -1 to TP = +1). In other words, when a person in the vehicle regulates a certain desired sensation of heat TP, the control state for the air conditioning converges

  at a single point on a comfort line corresponding to the TP value.

  In the aforementioned conventional technology, when TP is set to zero, the control state for the air conditioning is fixed at point A on a comfort line corresponding to the line of TP = 0 shown in 11i 2801008 in Figure 3. The desired temperature in the passenger compartment Tset corresponds to a temperature TA determined on either side of point A, and the desired temperature of the air at the outlet of the evaporator corresponds to a temperature TVo, indicated by an intersection of the horizontal line passing through point A and the saturation curve. Furthermore, in the present invention, in the case where the RH value is fixed at 65%, when a desired feeling of heat TP is set to zero, the control state for the air conditioning is fixed at point B which is determined as the intersection of the comfort line corresponding to TP = 0 and the curve of RH = 65%. In other words, in the present invention, the desired temperature in the passenger compartment Tset, given relative to the setting of TP = 0, corresponds to a temperature TB determined on either side of point B, and the desired temperature of the air at the evaporator outlet corresponds to the temperature TV indicated by the intersection of the horizontal line passing through point B and the saturation curve. In addition, a comfortable relative humidity RH = 65% is obtained at point B. Since the range of 50 to 80% relative humidity is generally considered to be comfortable, in the present invention, a

adequate value in this range.

  The reason why such a state can be obtained at point B lies mainly in the calculation means 45 and 44 shown in FIG. 2. In the calculation means 45, the information on

  RH set relative humidity are incorporated into the TV value.

  Then, this value of TV is used for the calculation of the desired temperature in the passenger compartment Tset in the calculation means 44. Therefore, using the control shown in Figure 2, the point for controlling the air conditioning is fixed at limited point B

  by the information on RH set relative humidity.

  In the present invention, a temperature TV greater than a temperature TVo determined by conventional technology is therefore supplied as the desired temperature of the air at the outlet of the evaporator for the same sensation of desired heat TP = 0. This is why , in the present invention, the cooling produced by the evaporator can be eliminated, which saves energy intended for the air conditioning system. In addition, in the present invention, a relative humidity can be obtained which lies within a comfort range, which is

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  higher than an extremely low relative humidity produced by the

conventional technology.

  FIG. 4 represents a control of an air conditioning system for vehicles according to a second embodiment of the present invention. In this embodiment, as shown in FIG. 1, a humidity sensor 32 is installed to detect a relative humidity in the passenger compartment. In this embodiment, the command is substantially the same as that shown in FIG. 2, except that, in this command, it is the signal 62 of the humidity in the passenger compartment RHS detected by the sensor humidity 32 which is sent and that it is the signal 48 of the cabin temperature TR detected by the interior air temperature sensor 28 which is sent to the desired temperature calculation means in the cabin 44. this fact, the operation obtained is an operation similar to that shown in FIG. 3. Since the humidity in the RHS passenger compartment is determined not by estimation, but by real detection, a pleasant feeling of

more precise desired heat.

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Claims (8)

  1. Air conditioning system (1) for vehicles, characterized in that it comprises: a) a variable displacement compressor (12); b) an air duct (2) equipped with a fan (7) and having air outlet orifices (19, 20, 21) opening towards a passenger compartment; c) an evaporator (8) arranged in said air duct (2), said evaporator (8) being connected to said compressor (12) via a refrigerant circuit (11) and ensuring cooling and dehumidification air passing through said air duct (2); d) a heater (9) disposed in said air duct (2) in a position downstream of said evaporator (8), said heater being capable of adjusting its heating efficiency of the air; e) means for determining the humidity by detecting the humidity of said passenger compartment or by estimating a state variable determining the humidity in said passenger compartment; f) means for controlling the efficiency of said evaporator (8) by controlling the movement of said compressor (12) and by adjusting the cooling and dehumidification efficiency of said evaporator (8); g) means for controlling the temperature in said passenger compartment by adjusting the efficiency of said heater (9); and h) means for adjusting the sensation of heat capable of arbitrarily adjusting a target value of a heat sensation index which corresponds to said sensation of heat, said cabin temperature control means varying the temperature from cockpit to be monitored according to various information, in particular the humidity in the cockpit detected or   estimated by said humidity determination means.   2. Air conditioning system (1) according to claim 1, characterized in that said humidity determination means estimate the dew point temperature in said passenger compartment, or a state variable correlated with it, at as a factor for determining said humidity in said passenger compartment, and said passenger compartment temperature control means have a calculation factor intended to reduce said passenger compartment temperature to be monitored according to a 14 2801008   elevation of said estimated dew point temperature or of said   state variable correlated with it.   3. Air conditioning system (1) according to claim 2, characterized in that said dew point temperature is estimated as a function of a state variable correlated with the efficiency of   cooling / dehumidification of said evaporator (8).   4. Air conditioning system (1) according to claim 1, characterized in that it comprises a humidity sensor (32), said humidity determination means determine said humidity in said passenger compartment in response to a signal from said sensor humidity (32), and said cabin temperature control means has a calculation factor for reducing said cabin temperature to be monitored as a function of a determined rise in humidity. 5. Air conditioning system (1) according to claim 1 or 4, characterized in that said cabin temperature control means determine said cabin temperature to be monitored according to an ambient temperature in the cabin and a humidity relative determined.   6. Air conditioning system (1) according to any preceding claim, characterized in that the displacement of said compressor (12) is adjusted so that a relative humidity in said passenger compartment is controlled to remain between 50 and 80%.   7. Air conditioning system (1) according to any one of the preceding claims, characterized in that means intended to control the movement of said compressor (12) comprise means intended to control discontinuous operation of the   on / off system of said compressor (12).   8. Air conditioning system (1) according to any preceding claim, characterized in that the displacement of said compressor (12) is adjusted to an arbitrary displacement in response to an external signal.