Abstract:
The presently disclosed invention uses a heating and cooling circuit to produce both heating and cooling effects through one single air-conditioning unit. It operates in one refrigeration cycle to provide both heating and cooling effects to control the temperature in an electric vehicle&#39;s passenger compartment. It also includes a self heat-up component to prevent the outside heat exchanger from getting frozen when the outside temperature drops below 32° F.

Description:
COPYRIGHT NOTICE 
       [0001]    A portion of the disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to vehicle passenger compartment heating and cooling technologies. 
       BACKGROUND 
       [0003]    The environmental problems caused by excessive use and exploitation of non-renewable energy resources are becoming severe, which results in degradation of our living environment and various damages to human society. The necessity to use clean energy and improve the efficiency of energy use becomes pressing. Electric vehicles are becoming popular by the day for its use of electricity with less negative impact on the environment than the traditional vehicles powered by fossil fuel. As to the impact to the environment, the prior air-conditioning units in electrical vehicles are not energy-efficient in terms of the amount of energy/electricity required to produce both the cooling and the heating effects. These air-conditioning units use two separate systems, one for cooling using refrigeration cycle and the other for heating using a separate electrical heater, which consumes more electricity than necessary, and causes excessive drain on the electric vehicle&#39;s battery. 
         [0004]    The refrigeration cycle uses the fluid refrigerant to move heat from one place to the other place. This cycle usually cools one place but produces heat to another place, which is often considered as one disadvantage of air-conditioning units. However, thinking backward, this cycle can also be used to move heat from one place to another place, which is the principle of the heating mode in the presently disclosed invention. By reversing the circulating directions, both heating and cooling effects can be achieved without consuming extra energy. 
         [0005]    The presently disclosed invention uses a heating and cooling circuit to produce both heating and cooling effects through one single air-conditioning unit. It operates in one refrigeration cycle to provide both heating and cooling effects to control the temperature in the electric vehicle&#39;s passenger compartment. It also includes a self heat-up component to prevent the outside heat exchanger from getting frozen when the outside temperature drops below 32° F. 
         [0006]    U.S. Patent Application Publication No. 2009/0260386 (hereinafter referred to as Wittmann) discloses a heating and air conditioning device for automotive vehicle, which comprises of a refrigerant circuit in which a refrigerant circulates between an evaporating unit, a cooling unit and a reversible unit. However, unlike the presently disclosed invention, the Wittmann device achieves temperature exchange through the use of secondary liquid loops. In a sense, it is similar to a HVAC refrigerant chiller machine, cooling or heating a tank of chiller water then delivering the water to different floors of the building. The presently disclosed invention, on the other hand, uses the same circulating path to create both heating and cooling effects by changing the direction of refrigerant flow through a reversing valve. 
         [0007]    In U.S. Pat. No. 5,284,025, (hereinafter referred to as Kajitani), an air conditioning system is disclosed as including a compressor, an outside air heat exchanger, an expansion valve, an interior heat exchanger, an interior heat exchanger fan, and a four-way switching valve. Although the Kajitani system is described to be used in electrically-powered motor vehicle, it is different from the presently disclosed invention in that it switches between heating and cooling modes by selecting two separate air ducts with one capturing heated air from drive shaft motor for heating and one capturing outside traveling air for cooling. The presently disclosed invention, on the other hand, uses the same heat exchangers and the same refrigerant circuits to create both heating and cooling effects by changing the direction of refrigerant flow through a reversing valve. 
         [0008]    U.S. Pat. No. 6,418,745 (hereinafter referred to as Ratliff) also describes heat pump system that is capable of switching between heating or cooling modes. However, unlike the presently disclosed invention, the Ratliff system achieves the objectives of heating and cooling by utilizing a thermal four-chambered compressor having a double piston head. 
       SUMMARY 
       [0009]    The presently disclosed invention includes a heating and cooling air-conditioning system for electric vehicles with both heating and cooling performance coming from the same refrigeration cycle, which saves more energy than prior air-conditioning units using two separate systems (refrigeration cycle and electric heater). 
         [0010]    The system includes heat exchangers to provide either cooling air or the heating air to the passenger saloon air duct during cooling mode or heating mode respectively. Passengers can select heating or cooling as the operation mode of the refrigeration cycle. 
         [0011]    The system uses the same circulating path to create both heating and cooling effects by changing the direction of refrigerant flow through a reversing valve. When heating mode is selected, compressed vapor refrigerant produced by a direct current (DC) electric compressor is supplied to the reversing valve where the vapor refrigerant is directed into the passenger saloon&#39;s heat exchanger with high temperature/pressure. In the passenger saloon, the vapor refrigerant releases heat energy with airflow from a blower fan. After heat is released, the vapor refrigerant becomes liquid refrigerant, which then goes through a capillary tube to the outside heat exchanger with low temperature/pressure, and absorbs heat energy from the outside atmosphere with airflow from an axial fan. The liquid refrigerant becomes the vapor refrigerant and goes back to the compressor through the reversing valve to start a new cycle again. 
         [0012]    During heating operation, moisture in outside atmosphere may freeze on the outside heat exchanger if its surface temperature drops below 32° F. When outside temperature falls below about 40° F., a flow valve will open and supply the hot refrigerant vapor to a heat-up exchanger, where heat energy will be transferred to the nearby outside heat exchanger through airflow blown by the axial fan. The outside heat exchanger absorbs heat energy and will not get frozen. 
         [0013]    When cooling mode is selected, the compressed vapor refrigerant produced by the DC electric compressor is supplied to the reversing valve where the vapor refrigerant is directed into the outside heat exchanger with high temperature/pressure. The vapor refrigerant then releases heat energy to the outside atmosphere with airflow from the axial fan. After heat is released, the vapor refrigerant becomes liquid refrigerant, which then goes through a capillary to the passenger saloon heat exchanger with low temperature/pressure, and absorbs heat energy from passenger compartment with airflow from the blower fan. The liquid refrigerant becomes the vapor refrigerant and goes back to the compressor through the reversing valve to start a new cycle again. 
         [0014]    In accordance with one aspect of the invention, a method of heating and cooling supply includes circulating refrigerant in a closed loop system, which includes a passenger saloon heat exchanger and an outside heat exchanger. The circulating step is completed solely through compressing vapor refrigerant with a DC electric compressor. 
         [0015]    According to another aspect of the present invention, the switch between heating and cooling of the heat exchanger is conducted through a reversing valve. 
         [0016]    According to another aspect of the present invention, the change of refrigerant from liquid to vapor is completed through a capillary tube. 
         [0017]    According to another aspect of the present invention, the change of the refrigerant&#39;s pressure from high to low is completed through a capillary tube instead of the commonly-used expansion valve. 
         [0018]    According to another aspect of the present invention, a method of providing heat to the outside heat exchanger to prevent it from being frozen when the outside temperature drops below 32° F. is conducted by a heat-up exchanger using the refrigerant vapor from the existing refrigeration cycle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Embodiments of the invention are described in more detail hereinafter with reference to the drawings, in which 
           [0020]      FIG. 1  is a schematic representation of the heating and cooling circuit of an embodiment of the claimed invention; 
           [0021]      FIG. 2  is a schematic representation showing the circulating route of the refrigerant during heating mode; and 
           [0022]      FIG. 3  is a schematic representation showing the circulating route of the refrigerant during cooling mode. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    In the following description, systems of heating and cooling air-conditioning systems are set forth as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions may be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention; however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation. 
         [0024]    Referring to  FIG. 2 , cool liquid refrigerant enters outside heat exchanger  3  through the capillary tube  4 . When inside the outside heat exchanger  3 , the liquid refrigerant absorbs heat as it changes state from liquid to vapor. The heat comes from the outside atmosphere with airflow from axial fan  9 . As air passes over the cooled outside heat exchanger  3 , it gives up some of its heat and moisture may condense from it. The cooler and drier air is expelled through the axial fan  9  into the outside atmosphere. The vapor refrigerant now goes into compressor  1  (which is basically a pump that raises the pressure) through reversing valve  6 . Once it passes through the compressor  1 , the refrigerant is on the “high” side of the system. The increased pressure from the compressor causes the temperature of the vapor refrigerant to rise. As it leaves the compressor  1 , the refrigerant becomes hot vapor. The hot vapor refrigerant now flows into passenger saloon heat exchanger  5  by circling back through the reversing valve  6 , and condenses at the passenger saloon heat exchanger  5 . As it condenses, the hot vapor refrigerant gives up heat to the saloon air blown across by blower fan  10 . The saloon air absorbs the heat from the passenger saloon heat exchanger  5  and is expelled into the passenger compartment. As the refrigerant leaves the passenger saloon heat exchanger  5 , it becomes liquid refrigerant, but still under pressure. The refrigerant then reaches the capillary tube  4 . The capillary tube  4  allows the high-pressure refrigerant to change into cooled liquid with lower pressure. The cycle is completed as the cooled liquid refrigerant re-enters the outside heat exchanger  3  to pick up heat from outside atmosphere. 
         [0025]    In summary, the passenger saloon heat exchanger  5  and outside heat exchanger  3  are where the refrigerant changes states between liquid and vapor, absorbing or releasing heat through boiling and condensing. The compressor  1  and capillary tube  4  facilitate the pressure changes with the compressor  1  increasing the pressure and the capillary tube  4  reducing the pressure. The reversing valve  2  and  6  is used to reverse the pressure cycle between the passenger saloon heat exchanger  5  and the outside heat exchanger  3 . 
         [0026]    During heating mode operation, moisture in the outside atmosphere may condense and freeze on the outside heat exchanger  3  if the outside temperature drops below 32° F. When outside temperature falls below about 40° F., flow valve  12  will open and supply the hot vapor refrigerant from the reversing valve  6  to heat-up exchanger  11  where the refrigerant releases heat and condenses. The released heat will then be absorbed by the outside heat exchanger  3  by the carrier airflow blown by the axial fan  9 . The absorbed heat defrosts the outside heat exchanger  3 . After the refrigerant leaves the heat-up exchanger  11 , it becomes cooler and then reaches the inlet of the capillary tube  4  connected through flow valve  13  where it joins the main cycle of the refrigerant again. 
         [0027]    Referring to  FIG. 3 , cooled liquid refrigerant enters the passenger saloon heat exchanger  5  through the capillary tube  4 . When inside the passenger saloon heat exchanger  5 , the liquid refrigerant absorbs heat as it changes state from liquid to vapor. The heat comes from the warm moist passenger saloon air circulated across the heat exchanger by blower fan  10 . The cooler and drier saloon air is re-circulated by the blower fan  10  into the saloon to cool the passenger compartment. The vapor refrigerant now goes into the compressor  1  (which is basically a pump that raises the pressure) through reversing valve  2 . Once it passes through the compressor  1 , the refrigerant is on the “high” side of the system. The increased pressure from the compressor  1  causes the temperature of the refrigerant to rise. As it leaves the compressor  1 , the refrigerant becomes hot vapor. The hot vapor refrigerant then flows to the outside heat exchanger  3  by circling back through the reversing valve  2 , and condenses at the outside heat exchanger  3 . As it condenses, the hot vapor refrigerant gives up heat to the outside air blown across by the axial fan  9 . The outside air absorbs heat from the outside heat exchanger  3 . As the refrigerant leaves the outside heat exchanger  3 , it becomes cooler, but still under pressure provided by the compressor  1 . The refrigerant then reaches the capillary tube  4 . The capillary tube allows the high-pressure refrigerant to change into cooled liquid with lower pressure. When pressure is reduced the refrigerant gets cooled. The cycle is completes as the cooled liquid refrigerant re-enters the passenger saloon heat exchanger  5  to absorb heat from the saloon. 
         [0028]    In summary, the passenger saloon heat exchanger  5  and outside heat exchanger  3  are where the refrigerant changes states, absorbing or releasing heat through boiling and condensing. The compressor  1  and capillary tube  4  facilitate the pressure changes with the compressor  1  increasing the pressure and the capillary tube  4  reducing the pressure. The reversing valve  2  and  6  is used to reverse the pressure cycle between the passenger saloon heat exchanger and outside heat exchanger.