Abstract:
The invention relates to a radiator fan control for heat pump HVAC which can selectively reverse fan direction based on ambient temperature and reduce ice buildup on a liquid-gas converter. In one embodiment, the invention is an automobile with a liquid-gas converter located within an engine bay, a radiator located adjacent the liquid-gas converter, a first fan located adjacent the radiator, a fuel cell and motor with the inverter located adjacent the first fan, the fuel cell supplying electricity to the motor with the inverter to drive the vehicle. The invention can also include a temperature sensor located on an exterior surface the automobile to sense an ambient temperature, a heater core connected to the liquid-gas converter and located between the engine bay and the passenger area, and a control unit connected to the first fan, the temperature sensor, and the heater core.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    The invention relates to a radiator fan control for heat pump HVAC. More particularly, the invention relates to a radiator fan control for heat pump HVAC which can selectively reverse fan direction based on ambient temperature and reduce ice buildup on a liquid-gas converter. 
         [0003]    2. Background 
         [0004]    Traditionally, automobiles utilize heat from an internal combustion engine to warm air that is to be distributed into a passenger area of an automobile. In automobiles with high technology energy use such as fuel cells, an engine in the automobile may be relatively efficient such that it does not generate sufficient heat to warm the passengers of the automobile. Thus, an HVAC system may need to include an active heating system to generate heat to distribute to passengers in the automobile. 
         [0005]    However, an HVAC system that actively generates heat generally absorbs energy from the ambient air to the automobile to produce the heat. This can be problematic when there is a low temperature in the ambient air because it is difficult to extract energy from ambient air with low energy. Furthermore, the absorption of energy can cause ice to build up on the HVAC system, particularly on the components that are absorbing energy from the ambient air. This is also problematic because the ice build up can also make it more difficult to absorb energy from the ambient air to convert to heat for the passengers. 
         [0006]    The ice build up can also be accelerated if there is high moisture content in the air, such as when there is rain, fog, snow, or a relatively high humidity. Furthermore, if the automobile is moving forward, for example, the rain, fog, snow, or air with a relatively high humidity could be forced onto the automobile. This problem is also exacerbated if the automobile is moving at a relatively fast speed as more rain, fog, snow, or air with a relatively high humidity strikes the automobile. Thus, considerable energy must be expended by the HVAC system to generate the heat for the passengers as it seeks to absorb energy from the ambient air with low temperature and/or high humidity (i.e., moisture content). 
         [0007]    Therefore, a need exists in the art for a HVAC system which can reduce ice build up on components of the HVAC system and which has an improved efficiency. 
       SUMMARY 
       [0008]    In one embodiment, the present invention is an automobile including a frame having an exterior surface, a first portion defining an engine bay, and a second portion defining a passenger area, a liquid-gas converter located within the engine bay, a radiator located adjacent the liquid-gas converter, a first fan located adjacent the radiator, a fuel cell and/or motor with the inverter located adjacent the first fan, the fuel cell supplying electricity to the motor and inverter to operate the motor, a temperature sensor located on or near the exterior surface of the automobile to sense an ambient temperature, a heater core connected to the liquid-gas converter and located between the engine bay and the passenger area, and a control unit connected to the first fan, the temperature sensor, and the heater core. 
         [0009]    When the ambient temperature is below a predetermined temperature, the control unit sends a first signal to the first fan to rotate in a first direction to direct air from an area around the engine towards the liquid-gas converter, and when the ambient temperature is not below the predetermined temperature, the control unit sends a second signal to the first fan to rotate in a second direction to direct ambient air towards the liquid-gas converter. 
         [0010]    In another embodiment, the present invention is a method for reducing energy consumption in a HVAC system in an automobile includes the steps of determining an ambient temperature of air adjacent to an exterior of the automobile, transmitting air heated by an engine and a fuel cell to a liquid-gas converter located at a front portion of the automobile when the ambient temperature is below a predetermined temperature, and reducing an amount of ice that forms on the liquid-gas converter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The features, objects, and advantages of the invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein: 
           [0012]      FIG. 1  is a schematic diagram of an HVAC system according to an embodiment of the invention; 
           [0013]      FIG. 2  is schematic diagram of the HVAC system according to an embodiment of the invention; 
           [0014]      FIG. 3  is a graph of assumed ambient temperature over time according to an embodiment of the invention; 
           [0015]      FIG. 4  is a graph of a comparison of fan speed over time according to an embodiment of the invention; 
           [0016]      FIG. 5  is a graph of a comparison of cabin temperature over time according to an embodiment of the invention; and 
           [0017]      FIG. 6  is a graph of a comparison of ice accumulation over time according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Apparatus, systems and methods that implement the embodiments of the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate some embodiments of the invention and not to limit the scope of the invention. Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements. 
         [0019]      FIG. 1  is a schematic diagram of the HVAC system in operation. As shown in  FIG. 1 , an automobile  2  comprises a frame  64  with an engine bay  68  and a passenger area  70 . The automobile  2  can also comprise a liquid gas-converter  4 , a radiator  10 , a radiator fan  12 , a coolant pump  18 , a fuel cell  24 , a motor with an inverter  26 , a heater core  28 , a heating, ventilating, and air conditioning (“HVAC”) compressor  30 , a HVAC loop  22 , HVAC fluid  40 , a cabin fan  32 , a temperature sensor  16 , a moisture sensor  66 , and a control unit  14 . 
         [0020]    The HVAC system can comprise, for example, liquid gas-converter  4 , radiator fan  12 , heater core  28 , HVAC compressor  30 , HVAC loop  22 , HVAC fluid  40 , cabin fan  32 , temperature sensor  16 , moisture sensor  66 , and/or control unit  14 . 
         [0021]    HVAC fluid  40  can flow through HVAC loop  22  and can be in a liquid state, a gaseous state, or a combination of liquid and gaseous state. 
         [0022]    Liquid-gas converter  4  is located at a front of the automobile in the engine bay and is connected to HVAC compressor  30  by HVAC loop  22 . In one embodiment, liquid gas-converter  4  is an apparatus incorporating a condenser and an evaporator in one device such that it can convert HVAC fluid  40  from liquid to gas when necessary and gas to liquid when necessary. In another embodiment, liquid-gas converter  4  can be just an evaporator to convert HVAC fluid  40  from liquid to gas or just a condenser to convert HVAC fluid  40  from gas to liquid. 
         [0023]    HVAC compressor  30  is connected to both liquid-gas converter  4  and heater core  28  through HVAC loop  22 . HVAC compressor  30  can raise or lower a pressure of HVAC fluid  40  flowing within HVAC loop  22 . 
         [0024]    Heater core  28  is connected to HVAC compressor  30  and liquid-gas converter  4  through HVAC loop  22 . Cabin fan  32  is located adjacent to heater core  28  to transmit warm air from heater core  28  to passenger area  70 . 
         [0025]    Radiator  10  is located behind liquid-gas converter  4  and is connected to coolant pump  18  through coolant loop  20 . Although radiator  10  is located behind liquid-gas converter  4 , it is contemplated that radiator  10  could be located in front of liquid-gas converter  4 . Radiator  10  can cool coolant fluids running through coolant loop  20  which are used to cool fuel cell  24  and/or motor with the inverter  26 . 
         [0026]    Coolant pump  18  is connected to radiator  10  and fuel cell  24  and/or motor with the inverter  26  through coolant loop  20 . Coolant pump  18  aids in circulating coolant fluid through fuel cell  24 , motor with the inverter  26 , and/or radiator  10 . 
         [0027]    Optional fuel cell  24  is connected to coolant pump  18  and motor with the inverter  26  through coolant loop  20 . Fuel cell  24  supplies electricity to motor with the inverter  26  which can be used to move automobile  2 . In one embodiment, fuel cell  24  is an electrochemical energy conversion device and can produce electricity from various external quantities of fuel on an anode side and an oxidant on a cathode side. The fuel and the oxidant react through an electrolyte. 
         [0028]    Fuel cell  24  can accomplish this, for example, by combining hydrogen and oxygen to produce dihydrogen oxide (water) and/or vapor. By combining hydrogen and oxygen, fuel cell  24  can generate electricity which can be used by motor with the inverter  26  to move automobile  2 . Use of fuel cell  24  instead of a conventional battery can be advantageous for longer driving range per one fueling/charging and for shorter fueling/charging time. Fuel cell  24  can be cooled by coolant loop  20  as coolant fluid within coolant loop  20  can absorb heat from fuel cell  24 . 
         [0029]    Motor with the inverter  26  is connected to fuel cell  24  and radiator  10  through coolant loop  20 . Coolant loop  20  can be used to cool and dissipate heat from motor with the inverter  26  by running coolant fluid through coolant loop  20  to absorb heat from motor with the inverter  26 . 
         [0030]    It is also contemplated that while fuel cell  24  and motor with the inverter  26  are used by automobile  26 , the present invention can also be used with other energy sources and engines which may not have sufficient heat to produce enough heat to heat passenger area  70  by themselves, such as diesel engines, direct injection gasoline engines, gas-electric hybrid engines, electric motors and/or combination of these power trains. 
         [0031]    Radiator fan  12  is located behind radiator  10  and is connected to control unit  14 . In another embodiment, radiator fan  12  can be located behind radiator  10 , and radiator fan  12  can also be located in front of radiator  10  between radiator  10  and liquid-gas converter  4 . In yet another embodiment, radiator fan  12  can be located in front of both radiator  10  and liquid-gas converter  4 . Radiator fan  12  can rotate in a first direction  74  to blow air from an area around fuel cell  24  and/or motor with the inverter  26  towards radiator  10  and/or liquid-gas converter  4 . Radiator fan  12  can also rotate in a second direction  76  to suck air from outside automobile  2  towards liquid-gas converter  4 , radiator  10 , fuel cell  24 , and/or motor with the inverter  26 . 
         [0032]    Temperature sensor  16  is located on or near the exterior of automobile  2  and is connected (via wires or wireless) to control unit  14 . Temperature sensor  16  detects the ambient temperature of the air outside automobile  2 . Temperature sensor  16  can be located immediately in front of liquid-gas converter  4 , to the side of liquid-gas converter, on a bottom (not shown) of automobile  2 , a front bumper (not shown) of automobile  2 , a windshield (not shown) of automobile  2 , a door (not shown) of automobile  2 , a rear bumper (not shown) of automobile  2 , a window (not shown) of automobile  2 , a door panel (not shown) of automobile  2 , an engine hood (not shown) of automobile  2 , a roof (not shown) of automobile  2 , and/or any other location of automobile  2 . Furthermore, there can be more than one temperature sensor  16  to address different locations of automobile  2  to receive a more accurate reading of the ambient temperature of the air outside automobile  2 . 
         [0033]    Optional moisture sensor  66  is located on or near the exterior of automobile  2  and is connected to control unit  14 . Moisture sensor  66  detects the ambient moisture content of the air outside automobile  2 . For example, moisture sensor  66  can detect the amount of ambient moisture or relatively humidity of the ambient air. Furthermore, moisture sensor  66  can also detect whether there is condensation such as rain, fog, or snow in the ambient air. Moisture sensor  66  can be located immediately in front of liquid-gas converter  4 , to the side of liquid-gas converter, on a bottom (not shown) of automobile  2 , a front bumper (not shown) of automobile  2 , a windshield (not shown) of automobile  2 , a door (not shown) of automobile  2 , a rear bumper (not shown) of automobile  2 , a window (not shown) of automobile  2 , a door panel (not shown) of automobile  2 , an engine hood (not shown) of automobile  2 , a roof (not shown) of automobile  2 , and/or any other location of automobile  2 . Furthermore, there can be more than one moisture sensor  66  to address different locations of automobile  2  to receive a more accurate reading of the ambient moisture outside automobile  2 . 
         [0034]    It is also contemplated that temperature sensor  16  and moisture sensor  66  can be located in relatively the same location of automobile  2 . Furthermore, it is also contemplated that temperature sensor  16  and moisture sensor  66  can be combined into one device. 
         [0035]    Control unit  14  is connected to temperature sensor  16 , moisture sensor  66 , and radiator fan  12 . Control unit  14  can send a first signal to radiator fan  12  to rotate radiator fan  12  in a first direction to blow air from an area around fuel cell  24  and/or motor with the inverter  26  towards radiator  10  and/or liquid-gas converter  4 . Control unit  14  can send the first signal to radiator fan  12  when, for example, the ambient temperature is below a predetermined temperature. Control unit  14  can also send the first signal to radiator fan  12  when, for example, the ambient temperature is below a predetermined temperature and the amount of ambient moisture is above a predetermined amount. 
         [0036]    The predetermined temperature can be, for example, −5° C., 0° C., 5° C., 10° C., 15° C., or any other suitable temperature to prevent or reduce ice accumulation on liquid-gas converter  4 . Advantageously, if the predetermined temperature is selected at a temperature above 0° C. such as 5° C., more energy can be removed from the ambient air without the ambient air freezing and forming ice on liquid-gas converter  4 . In one embodiment, when there is a low-moisture content in the air, the predetermined temperature can be low such as −5° C. or 0° C. In another embodiment, when there is a high moisture content in the air, it is preferable that the predetermined temperature be 10° C. or above. 
         [0037]    Similarly, control unit  14  can also send a second signal to radiator fan  12  to rotate radiator fan  12  in a second direction to pull or suck air from outside automobile  2  towards liquid-gas converter  4 , radiator  10 , fuel cell  24 , and/or motor with the inverter  26 . Control unit  14  can send the second signal to radiator fan  12  when, for example, the ambient temperature is not below a predetermined temperature. Control unit  14  can also send the second signal to radiator fan  12  when, for example, the ambient temperature is not below a predetermined temperature and the ambient moisture is not above a predetermined amount. 
         [0038]    As seen in  FIG. 2 , in operation, automobile  2  generally travels in a forward direction  72 . When passengers are cold and/or want to warm passenger area  70 , a passenger can send a signal to control unit  14  by depressing a button (not shown) or shifting a knob (not shown). Temperature sensor  16  detects the ambient temperature and moisture sensor  66  detects the ambient moisture content of air  6  outside automobile  2 . 
         [0039]    When the ambient temperature of air  6  is not below a predetermined temperature, control unit  14  sends the second signal to radiator fan  12 . Radiator fan  12  then rotates in a second direction  76  to suck air  6  from outside automobile  2  towards liquid-gas converter  4 . Air  8  from air  6  is directed towards radiator  10 , fuel cell  24 , and/or motor with the inverter  26 . Through a combination of liquid-gas converter  4  and HVAC compressor  30  or solely through liquid-gas converter  4 , HVAC fluid  40  flowing through HVAC loop  22  is evaporated and is completely or partially converted from liquid to gas. Converting HVAC fluid  40  from liquid to gas removes energy from air  6  and stores the energy in HVAC fluid  40 . HVAC fluid  40  is compressed by compressor  30  and heater core  28  disperses the energy accumulated in HVAC fluid  40  in warm air  34 . Cabin fan  32  then blows warm air  44  from warm air  34  to passengers in passenger area  70 . 
         [0040]    As seen in  FIG. 1 , in one embodiment when the ambient temperature is below a predetermined temperature, control unit  14  sends the first signal to radiator fan  12 . In another embodiment, when the ambient temperature is below a predetermined temperature and the ambient moisture content is above a predetermined amount, control unit  14  sends the first signal to radiator fan  12 . 
         [0041]    Once radiator  12  receives the first signal, radiator fan  12  rotates in a first direction  74  to blow air  44  from an area around fuel cell  24  and/or motor with the inverter  26  towards radiator  10 . Air  42 , which is air  44  after air  42  has passed through radiator  10 , traverses through liquid-gas converter  4 . Air  38 , which is air  42  after air  38  has passed through liquid-gas converter  4 , exits automobile  2 . Even if fuel cell  24  and/or motor with the inverter  26  does not generate sufficient heat to warm passenger area  70  by themselves, it is contemplated that fuel cell  24  and/or motor with the inverter  26  may generate sufficient heat to prevent ice build up on liquid-gas converter  4 . Furthermore, components aside from fuel cell  24  and/or motor with the inverter  26  can generate heat which can warm air  44  such as coolant pump  18 , a hydrogen pump (not shown), or any other device used within automobile  2 . 
         [0042]    Through a combination of liquid-gas converter  4  and HVAC compressor  30  or solely through liquid-gas converter  4 , HVAC fluid  40  flowing through HVAC loop  22  is evaporated and is completely or partially converted from liquid to gas. 
         [0043]    Converting HVAC fluid  40  from liquid to gas removes energy from air  42  and stores the energy in HVAC fluid  40 . Since air  42  is warmer than the ambient air, it is easier to remove energy from air  42  than it is to remove energy from the ambient air. Furthermore, the removal of energy from air  42  may be less likely to create ice on liquid-gas converter  4  since the removal of energy from air  42  may not be sufficient to chilly air  42  such that air  42  forms ice on liquid-gas converter  4 . Also, since air  42  is from air  44 , it may have less moisture content than the ambient air since there may not be rain, fog, and/or snow in air  44 . 
         [0044]    Less ice accumulation on liquid-gas converter  4  can also improve the efficiency of liquid-gas converter  4  since ice accumulation can serve to remove energy from liquid-gas converter  4 . In addition, a reduced amount of ice accumulation on liquid-gas converter  4  can also reduce the amount of weight on automobile  2 . This can improve the fuel efficiency of automobile  2  as heavier automobiles may require more energy to move than lighter automobiles. 
         [0045]    HVAC fluid  40  is compressed by compressor  30  and heater core  28  disperses the energy accumulated in HVAC fluid  40  in warm air  46 . Cabin fan  32  then blows warm air  48  from warm air  46  to passengers in passenger area  70 . 
         [0046]    When the ambient temperature of air  6  is not below a predetermined temperature, control unit  14  sends the second signal to radiator fan  12  and radiator fan  12  switches from rotating in a first direction  74  back to rotating in a second direction  76 . 
         [0047]    Referring now to  FIGS. 3 ,  4 ,  5 , and  6 , some of the advantages of the invention over a conventional HVAC system may be seen during low humidity conditions. Low humidity conditions, for example, can be when there is a relatively low amount of moisture content in the ambient air.  FIG. 3  is a chart of assumed ambient temperature over time. 
         [0048]      FIG. 4  is a graph of a comparison of fan speed over time. A fan speed of a conventional radiator fan in a conventional HVAC system is indicated by line  52  while a fan speed of radiator fan  12  of the invention is indicated by line  54 . 
         [0049]      FIG. 5  is a graph of a comparison of cabin temperature over time. A temperature of a cabin or passenger area using the conventional HVAC system is indicated by line  58 . A temperature of a cabin or passenger area  70  using the invention is indicated by line  56 . 
         [0050]      FIG. 6  is a graph of a comparison of ice accumulation over time. Ice accumulation in a conventional condenser in a conventional HVAC system is indicated by line  60  while ice accumulation of the invention is indicated by line  62 . 
         [0051]    From time t 0  to time t 1 , the ambient temperature is below the predetermined temperature. Thus, radiator fan  12  rotates in the first direction drawing air  44  from an area around fuel cell  24  and/or motor with the inverter  26  as indicated by line  54 . However, the conventional fan is still rotating in the first direction at maximum speed as indicated by line  52  to retrieve maximum available energy. Since liquid-gas converter  4  is receiving air  44  which is warmer than the ambient air, the cabin temperature can increase at a more rapid rate than in conventional HVAC systems. Furthermore, while ice is accumulating on the conventional condenser as seen in line  60 , ice accumulation of the invention is minimal as seen in line  62 . Furthermore, since air  44  is warmer than the ambient air, radiator fan  12  does not need to rotate as fast as the conventional fan as seen in  FIG. 4 . 
         [0052]    At time t 1 , the ambient temperature is warmer than a predetermined temperature. Thus, at time t 1 , radiator fan  12  rotates in a second direction  76  drawing air from the outside. Since there is little ice accumulation on liquid-gas converter  4  as shown in  FIG. 6  when compared to the conventional condenser, radiator fan  12  does not need to rotate as fast as the conventional fan. 
         [0053]    Between time t 1  and time t 2 , the cabin temperature of the invention reaches the desired temperature as indicated by the plateau of the cabin temperature. 
         [0054]    At time t 2 , the conventional fan begins to reduce its speed as the cabin temperature is approaching the desired temperature. However, ice accumulation may still increase in the conventional condenser. 
         [0055]    At time t 3 , the conventional fan has the same rotational speed as radiator fan  12 . However, there is still ice accumulation on the conventional condenser. Sometime, between time t 2  and time t 3 , the cabin temperature of the conventional HVAC system reaches the desired temperature as indicated by the plateau of the cabin temperature. 
         [0056]    Notably, in the invention, radiator fan  12  can run at a reduced speed for a longer period of time. Furthermore, the invention increases the cabin temperature quicker such that it reaches the desired temperature quicker than in the conventional HVAC system. In addition, the invention has a reduced amount of ice accumulation on the liquid-gas converter  4  when compared with the ice accumulation on the conventional condenser. 
         [0057]    Those of ordinary skill would appreciate that the various illustrative logical blocks, modules, and algorithm steps described in connection with the examples disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed apparatus and methods. 
         [0058]    The various illustrative logical blocks, modules, and circuits described in connection with the examples disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
         [0059]    The steps of a method or algorithm described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an Application Specific Integrated Circuit (ASIC). The ASIC may reside in a wireless modem. In the alternative, the processor and the storage medium may reside as discrete components in the wireless modem. 
         [0060]    The previous description of the disclosed examples is provided to enable any person of ordinary skill in the art to make or use the disclosed methods and apparatus. Various modifications to these examples will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosed method and apparatus. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.