Abstract:
The present invention concerns a method for pre-cooling the passenger compartment of an automotive vehicle. The vehicle includes at least one electrically actuatable window and a HVAC system having at least a controller, a blower, a passenger compartment temperature sensor, and a HVAC ducting leading to the passenger compartment. The controller and the blower are connected to a vehicle battery. The method includes determining the passenger compartment temperature and comparing the temperature to a first predetermined value; cycling an blower inlet to an outside air intake position and operating the blower to provide pressurized air to the passenger compartment if the passenger compartment temperature is greater than the first predetermined value; opening the vehicle windows; comparing the passenger compartment temperature to a second predetermined value; and stopping operation of the blower when the passenger compartment temperature drops below the second predetermined value.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates generally to automotive vehicle heating, ventilation, and air conditioning (HVAC) systems and, in particular, to a method for pre-cooling the passenger compartment of an automotive vehicle.  
         [0002]     The passenger compartment of a vehicle parked in direct or indirect sunlight can become very hot, with temperatures greatly exceeding that of the ambient air temperature due to solar heat load on the window glass and the like. Vehicle owners often start a vehicle, engage the HVAC system to begin cooling the passenger compartment, and then exit the vehicle until the HVAC system actually begins to cool the passenger compartment. This method however, wastes fuel and increases the emissions of the vehicle. Remotely starting a vehicle and operating the HVAC system is also a known method for cooling the passenger compartment of the vehicle, however, this also wastes fuel and increases the emissions of the vehicle.  
         [0003]     It is desirable, therefore, to provide a method for cooling an interior of a vehicle without operating the engine and thereby wasting fuel and producing vehicle emissions.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention concerns a method for pre-cooling the passenger compartment of an automotive vehicle. The vehicle includes at least one electrically actuatable window and a HVAC system having at least a controller, a blower, at least one temperature sensor in the passenger compartment, and a HVAC ducting leading to the passenger compartment. The controller and the blower are connected to a vehicle battery. The method includes the steps of determining the temperature of the passenger compartment and comparing the temperature to a first predetermined value; cycling an inlet of the blower to an outside air intake position and operating the blower to provide pressurized air through the HVAC ducting to the interior of the vehicle if the temperature of the passenger compartment is greater than the first predetermined value; opening the windows of the vehicle; comparing the temperature of the passenger compartment to a second predetermined value; and stopping operation of the blower when the temperature of the passenger compartment drops below the second predetermined value.  
         [0005]     Alternatively, the HVAC system includes a HVAC compressor and the method in accordance with the present invention further includes the steps of starting the compressor, cycling the inlet of the blower to a recirculated position, and closing the windows of the vehicle.  
         [0006]     The method in accordance with the present invention is especially suited for those vehicles having electric-driven HVAC compressors, since the interior temperature may be cooled more quickly utilizing the HVAC system than utilizing ambient air only. The method in accordance with the present invention, however, may be advantageously utilized to pre-cool the passenger compartment of all types of vehicles regardless of the type of engine power plant or the type of prime mover of the refrigerant compressor including, but not limited to, non-hybrid vehicles with automatic climate control. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:  
         [0008]      FIG. 1   a  is a schematic view of a HVAC system that can be advantageously employed to carry out a method of pre-cooling a passenger compartment of an automotive vehicle in accordance with the present invention;  
         [0009]      FIG. 1   b  is a schematic view of an alternative embodiment of a HVAC system that can also be employed to carry out a method of pre-cooling a passenger compartment of an automotive vehicle in accordance with the present invention;  
         [0010]      FIG. 2  is a block diagram of a HVAC system in accordance with the present invention;  
         [0011]      FIGS. 3, 4 , and  5  are flowcharts of a method of operating the HVAC system of  FIGS. 1   a ,  1   b , and  2  in accordance with the present invention; and  
         [0012]      FIG. 6  is a flowchart of an alternative method of operating the HVAC system of  FIGS. 1   b  and  2  in accordance with the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]     Referring now to  FIGS. 1   a  and  1   b , a HVAC system is indicated generally at  10  in  FIG. 1   a  and at  10 ′ in  FIG. 1   b . The HVAC system  10  and  10 ′ is disposed in a vehicle, indicated generally at  12 . The vehicle  12  includes at least one and preferably a plurality of movable windows  13  formed therein. The vehicle  12  may be a hybrid vehicle having an internal combustion engine  14  operating in conjunction with a battery  29 , best seen in  FIG. 1   b , a conventional vehicle having the internal combustion engine  14  only, or an electric vehicle having the battery  29  only. If the vehicle  12  is a hybrid vehicle or an electric vehicle, the battery  29  is preferably a large storage battery. Alternatively, the engine  14  may be replaced by a fuel cell (not shown) or the like. The HVAC system includes a HVAC air duct  16  and a blower  18  adapted to direct a flow of air in a direction indicated by an arrow  17  through the HVAC duct  16 . An evaporator  20  is located within the HVAC duct  16  downstream of the blower  18 . A heater core  22  is located within the HVAC duct  16  downstream of the evaporator  20 . The evaporator  20  includes a refrigerant inlet  24  from and a refrigerant outlet  26  to a refrigerant circuit, indicated generally at  27 , including a refrigerant compressor  28 , shown in  FIG. 1   a . The compressor  28  is driven by the engine  14  through a clutch  30 . The compressor  28  may be a fixed displacement compressor or a variable displacement compressor, as will be appreciated by those skilled in the art. A compressor  28 ′, shown in  FIG. 1   b , is an electric-driven compressor connected to the vehicle battery  29 . The compressor  28 ′ may be a fixed displacement compressor or a variable displacement compressor, as will be appreciated by those skilled in the art. The refrigeration circuit  27 , of course, may also include a condenser (not shown), a receiver/dryer (not shown), and a thermostatic expansion valve or orifice tube (not shown) in fluid communication with the compressor  28  and the evaporator  20 . A refrigerant is contained in the refrigerant circuit  27  and so flows through the refrigerant inlet  24 , the refrigerant outlet  26 , the compressor  28  or  28 ′, and the evaporator  20 . The refrigerant is selectively circulated through the piping during operation of the HVAC system  10  or  10 ′, discussed in more detail below. The heater core  22  has a coolant inlet  32  from and a coolant outlet  34  to an engine cooling circuit, indicated generally at  31 , of the internal combustion engine  14 . A coolant (not shown), such as a glycol/water mixture or the like, is contained in the engine cooling circuit  31  and thus flows through the coolant inlet  32 , the coolant outlet  34 , the engine  14 , and the heater core  22 . The coolant selectively circulates through the engine cooling circuit  31  during operation of the HVAC system  10  or  10 ′, discussed in more detail below. A damper  36  is disposed in the HVAC duct  16  downstream of the evaporator  20  and adjacent the heater core  22 . The damper  36  includes an actuator (not shown) such as an electric motor or the like that is operable to selectively expose and block the heater core  22  to an air flow from the blower  18 . When the damper  36  is in a first position  36   a , the air flowing from the blower  18  in the direction  17  bypasses the heater core  22 . When the damper  36  is in a second position  36   b , the air flowing from the blower  18  in the direction  17  flows through the heater core  22 .  
         [0014]     A duct temperature measurement device  38 , such as a temperature sensor or the like, is disposed in the HVAC duct  16  downstream of the heater core  22 . The HVAC air duct  16  extends to a passenger compartment, indicated schematically at  40 . At least one passenger compartment temperature measurement device  42 , such as a temperature sensor or the like, is disposed in the passenger compartment  40 . A first damper  44  is disposed in the HVAC duct  16  downstream of the heater core  22  for distributing air to a floor outlet  46  in the passenger compartment  40 . A second damper  48  is disposed in the HVAC duct  16  downstream of the heater core  22  for distributing air to either or both of a torso outlet  50  or a windshield outlet  52  in the passenger compartment  40 . A recirculation damper  54  is disposed between an outside air intake (i.e. fresh air inlet)  56  and an inside air intake (i.e. recirculation air or return inlet)  58  from the passenger compartment  40  to supply air to the blower  18 . The recirculation damper  54  can move between a first position  54   a  and a second position  54   b . The recirculation damper  54  is operable to selectively provide only fresh air from the fresh air inlet  56  (when in the first position  54   b ), only recirculated air from the return inlet  58  (when in the second position  54   a ), or a mixture of fresh air and recirculated air to the blower  18 . Each of the dampers  44 ,  48  and the recirculation damper  54  include an actuator (not shown) such as an electric motor or the like for moving the dampers  44 ,  48  and  54  between the respective closed and open positions.  
         [0015]     Referring now to  FIG. 2 , the HVAC system  10  or  10 ′ includes a controller  60  electrically connected to and operatively engaging the compressor  28  (through the clutch  30  shown in  FIG. 1 ) or the compressor  28 ′ (through the battery  29  shown in  FIG. 2 ), the blower  18 , the duct temperature measurement device  42 , and the passenger compartment temperature measurement device  46 . The controller  60  is electrically connected to and operatively engages the respective actuators of the dampers  44 ,  48  and  54 . The controller  60  is electrically connected to and operatively engages at least one electrical actuator  62  for the at least one window  13  to open and close the at least one window  13  in a conventional manner known to those skilled in the art. The controller  60  is also connected to the battery  29  for measuring a power level of the battery  29  and to a timer  63  for initiating a timer during operation of the HVAC system  10  or  10 ′. The controller  60  is also connected to a hood sensor  57  and a fuel door sensor  59 , which provide an indication of the status of the hood and fuel door, respectively, to the controller  60 . The controller  60  is preferably an electronic control unit, such as an HVAC control unit or the like. The controller  60  may be a single microprocessor or a plurality of interconnected microprocessors. Furthermore, the controller  60  may be hardware, software, or any combination thereof as will be appreciated by those skilled in the art. The controller  60  is operable to receive signals, such as from the measurement devices  38  and  42  and the sensors  57  and  59  and to transmit commands, such as to the compressor  28  or  28 ′, the blower  18 , the actuators of the dampers  44 ,  48  and  54 , and the at least one actuator  62  of the at least one window  13  during operation of the HVAC system  10  or  10 ′, discussed in more detail below.  
         [0016]     The controller  60  is also operable to receive commands or signals from a remote communicator  64 . The remote communicator  64  includes a transmitter  66  for transmitting a signal when a push button  68  is actuated on the remote communicator  64 . The remote communicator  64  is preferably a key fob remote control device or the like. A receiver  61  on the controller  60  is operable to receive the command or signal transmitted from the transmitter  66  on the remote communicator  64 .  
         [0017]     Referring now to  FIG. 3 , a flowchart of a method of operating the HVAC system  10  or  10 ′ in accordance with the present invention is indicated generally at  100 . In a step  102 , a cooldown sequence is initiated. The cooldown sequence in the step  102  may be initiated by the vehicle owner actuating the push button  68  on the remote communicator  64  and initiating a command from the remote communicator  64 . Alternatively, the cooldown sequence in the step  102  may be initiated by the controller  60  comparing the temperature of the passenger compartment  40  measured by the temperature measurement device  42  to a first predetermined value stored in the controller  60 . If the temperature measured by the temperature measurement device  42  is greater than the first predetermined value, the cooldown sequence in the step  102  is initiated. In an alternative step  103 , a timer, such as the timer  63  shown in  FIG. 2 , is initiated after the step  102 . In a step  104 , the method proceeds to a subroutine for verifying the HVAC system  10  or  10 ′ is in condition to continue the method  100 .  
         [0018]     Referring now to  FIG. 4 , the subroutine  104  begins in a step  106  and proceeds to a step  108 , where the temperature of the passenger compartment  40  (T 1 ) measured by the temperature measurement device  42  is determined by the controller  60 . In a step  110 , the vehicle interior temperature T 1  is compared to a second predetermined value (T 2 ) stored in the controller  60 . The second predetermined value T 2  is preferably a lower temperature value at which it is not desirable to cool the passenger compartment  40 . The step  110  may be skipped if the controller  60 , rather than the vehicle owner actuating the push button  68  on the remote communicator  64 , initiated the cooldown sequence in the step  102 . If the measured temperature value T 1  is less than the second predetermined value T 2  (i.e., the temperature in the passenger compartment  40  has not reached a high value) the subroutine  104  proceeds to a step  112  and the subroutine  104  and the method  100  ends. If the measured temperature value T 1  is greater than the second predetermined value T 2 , (i.e., the temperature in the passenger compartment  40  has reached a value where it is desirable to cool the passenger compartment  40 ) the subroutine  104  proceeds to a step  114 , where the controller  60  compares a state of charge of the battery  29  with a predetermined state of charge value (C 1 ) stored in the controller  60 . If the state of charge of the battery  29  is less than C 1  (i.e., the battery charge is too low to operate the various components of the HVAC system  10  or  10 ′), the subroutine  104  proceeds to the step  112  and the subroutine  104  and the method  100  ends.  
         [0019]     If the state of charge of the battery  29  is greater than C 1 , the subroutine  104  proceeds to a step  116 , where a value of the timer  63  initiated in the step  103  is compared to a predetermined constant value (C 2 ) stored in the controller  60 . The constant value C 2  is preferably equal to a maximum desired amount of time that the method  100  is expected to run. If the value of the timer  63  is greater than the constant value C 2 , the subroutine  104  proceeds to a step  112  and the subroutine  104  and the method  100  ends. If the value of the timer  63  is less than the constant value C 2 , the HVAC system  10  or  10 ′ is in condition to continue the method  100  and the subroutine  104  proceeds to a step  118 , where the subroutine  104  ends and returns to the method  100  after the step  104 . Those skilled in the art will appreciate that other steps may be added to the method  100  while remaining within the scope of the present invention including, but not limited to, a step of comparing the value of T 1  with at least another predetermined temperature value, and stopping operation of the method  100  if the value of T 1  is below the at least another predetermined temperature value.  
         [0020]     In a step  120 , the controller  60  provides a signal to the actuator of the damper  54  to cycle the inlet of the blower  18  to the position  54   b , where only fresh air from the fresh air inlet  56  is provided to the blower  18 . The method  100  then proceeds to a step  122 , where the controller  60  provides a signal to the at least one actuator  62  of the at least one window  13  to open the at least one window  13 . Preferably in the step  122 , the at least one window  13  is opened a small predetermined distance, such as twenty five millimeters or the like. By opening the at least one window  13  the small predetermined distance in the step  122 , the security of the vehicle  12  is not compromised and the passenger compartment  40  of the vehicle  12  is not exposed to inclement weather or airborne contaminants. The method  100  then proceeds to a step  124 , wherein the controller  60  sends a signal to operate the blower  18 , bringing fresh air from the fresh air inlet  56  into the passenger compartment  40  through the outlets  46 ,  50 , and  52 , and forcing the hot air in the passenger compartment  40  out the opened window(s)  13 . The blower  18 , when operating, pressurizes the passenger compartment  40  and, therefore, the predetermined distance that the windows  13  are opened functions as a nozzle to force the hot air in the passenger compartment  40  through the opened windows  13  while minimizing the fresh air flowing out through the windows  13 . After the blower  18  has begun operation in the step  124  and preferably after a predetermined period of time, the method  100  proceeds to the step  126 , where the method proceeds to another subroutine to verify that the HVAC system  10  or  10 ′ is in condition to continue the method  100 .  
         [0021]     Referring now to  FIG. 5 , the subroutine  126  begins in a step  128  and proceeds to a step  130 , where the controller  60  compares a state of charge of the battery  29  with the predetermined state of charge value (C 1 ) stored in the controller  60 , similar to the step  114  shown in  FIG. 4 . If the state of charge of the battery  29  is less than C 1  (i.e., the battery charge is too low to operate the various components of the HVAC system  10  or  10 ′), the subroutine  126  proceeds to a step  132  and the subroutine  126  and the method  100  ends. Preferably, the operation of the blower  18  is stopped when the subroutine  126  and method  100  ends in the step  132 . Optionally, the windows  13  of the vehicle  12  are also closed in the step  132 . If the state of charge of the battery  29  is greater than C 1 , the subroutine  126  proceeds to a step  134 , where a value of the timer  63  initiated in the step  103  is compared to the predetermined constant value (C 2 ) stored in the controller  60 , similar to the step  116  shown in  FIG. 4 . The constant value C 2  is preferably equal to a maximum desired amount of time that the method  100  is expected to run. If the value of the timer  63  is greater than the constant value C 2 , the subroutine  126  proceeds to the step  132  and the subroutine  126  and the method  100  ends. If the value of the timer  63  is less than the constant value C 2 , the method proceeds to a step  135 , where the vehicle interior temperature T 1  is compared to a third predetermined value (T 3 ) stored in the controller  60 . The third predetermined value T 3  is preferably a lower temperature value at which it is desirable to stop cooling the passenger compartment  40 . If the measured temperature value T 1  is less than the third predetermined value T 3  (i.e., the temperature in the passenger compartment  40  is sufficiently cooled) the subroutine  126  proceeds to the step  132  and the subroutine  126  and the method  100  ends. If the measured temperature value T 1  is greater than the third predetermined value T 3 , the HVAC system  10  or  10 ′ is in condition to continue the method  100  and the subroutine  104  proceeds to a step  136 , where the subroutine  126  ends and returns to the method  100  at the step  126 . The method  100  then continues in a loop of the subroutine  126  while the blower  18  operates to cool the passenger compartment  40 . The blower  18  will continue to operate, therefore, while the state of charge of the battery  29  is greater than the value of C 1  and the value of the timer  63  is less than the value of C 2 .  
         [0022]     The method  100  in accordance with the present invention advantageously can pre-cool the temperature of a passenger compartment  40  within a short period of time after the sequence is initiated in the step  102  and can advantageously be accomplished prior to the occupants of the vehicle entering the vehicle. In testing, for example, a temperature in the passenger compartment  40  was lowered ten degrees Fahrenheit in less than one minute. Obviously, the amount of cooling and the amount of time taken to lower the temperature of the passenger compartment  40  is a function of the starting temperature of the passenger compartment  40 , the ambient outside air temperature, and the solar heat load on the vehicle  12  as well as the state of charge of the battery  29  when the method  100  begins at the step  102 .  
         [0023]     Referring now to  FIG. 6 , a flowchart of an alternative method of operating the HVAC system  10 ′ in accordance with the present invention is indicated generally at  100 ′. The method includes the steps  102  through  134  in  FIGS. 3-5  as described above. In the method  100 ′, after the subroutine  126  proceeds to the step  136 , instead of looping through the subroutine  126  until the state of charge of the battery  29  is less than C 1  or the value of the timer  63  is greater than C 2 , the method  100 ′ proceeds to a step  138 , where a timer, such as the timer  63  shown in  FIG. 2  or another timer, is incremented. Alternatively, the method  100 ′ proceeds directly to a step  140  after the expiration of a predetermined period of time, as will be appreciated by those skilled in the art.  
         [0024]     In the step  140 , the controller  60  sends a signal to operate the compressor  28 ′ and the refrigerant contained in the refrigerant circuit  27  begins flowing through the refrigerant inlet  24 , the refrigerant outlet  26 , the compressor  28 ′, and the evaporator  20  and the refrigerant absorbs heat from the air flowing in the HVAC duct through the evaporator  20  in a well known manner. After a predetermined period of time (which allows the refrigerant to begin cooling the air in the HVAC duct  16 ), the method  100 ′ proceeds to a step  142 , where the controller  60  provides a signal to the actuator of the damper  54  to cycle the inlet of the blower  18  from the position  54   b  to the position  54   a , where only recirculated air from the return air inlet  58  is provided to the blower  18 . After the step  142 , the method proceeds to a step  144 , where the controller  60  provides a signal to the at least one actuator  62  of the at least one window  13  to close the at least one window  13 . With the damper  54  in the position  54   a , the blower  18  is providing cooled and recirculated air to the passenger compartment  40  through the HVAC duct  16  and cooling the passenger compartment  40 . Alternatively, the step  144  may be skipped and the method proceeds directly to a step  146 . In the step  146 , the method  100 ′ proceeds to the subroutine  128  shown in  FIG. 5  and outlined in more detail above. The method  100 ′ then continues in a loop of the subroutine  126  while the blower  18  and the compressor  28 ′ operates to cool the passenger compartment  40 . The blower  18  and the compressor  28 ′ will continue to operate, therefore, while the state of charge of the battery  29  is greater than the value of C 1  and the value of the timer  63  is less than the value of C 2 . In addition, the method  100 ′ will also stop upon a signal received by the controller  60  from the hood sensor  57  indicating that the hood is opened or upon a signal received by the controller  60  from the fuel door sensor  59  indicating the fuel door is opened. Those skilled in the art will appreciate that other interlocks and shutdowns may stop the methods  100  or  100 ′ while remaining within the scope of the present invention. Preferably, the operation of the blower  18  is stopped and the windows  13  of the vehicle  12  are closed when the subroutine  126  and method  100 ′ ends in the step  132 . Optionally, the windows  13  of the vehicle  12  are also closed in the step  132 .  
         [0025]     The method  100 ′ in accordance with the present invention advantageously can pre-cool the interior temperature of a vehicle within a short period of time after the sequence is initiated in the step  102  and can advantageously be accomplished prior to the occupants of the vehicle entering the vehicle. In testing, for example, a temperature in the passenger compartment  40  was lowered forty degrees Fahrenheit in less than four minutes. Similar to the method  100 , the amount of cooling and the amount of time taken to lower the temperature of the passenger compartment  40  in the method  100 ′ is a function of the starting temperature of the passenger compartment  40 , the ambient outside air temperature, and the solar heat load on the vehicle  12  as well as the state of charge of the battery  29  when the method  100 ′ begins at the step  102 .  
         [0026]     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.