Abstract:
Disclosed is a heating, ventilation and air conditioning system for a vehicle that operates in a heating mode, a cooling mode or a demisting mode. In some embodiments, the system includes a first circuit having first pump for circulating a first medium therein, a second circuit having a second pump for circulating a second medium therein and a thermoelectric module having a first surface in thermal contact with the first medium and a second surface in thermal contact with the second medium.

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 11/101,871, filed Apr. 8, 2005, titled THERMOELECTRIC-BASED THERMAL MANAGEMENT SYSTEM, the entire contents of which are incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND 
     1. Field 
     This disclosure generally relates to heating, ventilation and air conditioning (“HVAC”) systems for a vehicle, and more particularly to HVAC systems having thermoelectric modules for providing thermal management to a passenger compartment of the vehicle. 
     2. Description of Related Art 
     In a conventional vehicle, such as an automobile, the heating of the passenger compartment is accomplished by running engine coolant, typically a mix of water and glycol, through a heat exchanger and then blowing air through the heat exchanger and into the passenger compartment. The drawback with this is that the heat exchanger will not provide heat until the engine has caused the coolant to warm up. In colder climates, the time to warm up the coolant can be lengthy, thereby delaying warming of passengers of the automobile. 
     Furthermore, newer engines and powertrain arrangements are being developed where the engine does not produce as much excess heat for the coolant to absorb. Some examples include direct injection engines and hybrid powertrains. For these types of engines and powertrains, the temperature of the coolant can take a very long time to rise to a level that will allow for adequate heating of the passenger compartment when using a conventional heating system. 
     Therefore, it is desired to provide a HVAC system that provides heat to the passenger compartment of the vehicle more quickly than a conventional system. 
     BRIEF SUMMARY 
     In overcoming the drawbacks and limitations of the known technologies, a system of thermal management the passenger compartment of an automobile is disclosed. The thermal management system includes a first circuit and a second circuit. The first circuit includes a first pump for circulating a first medium therethrough, a first heat exchanger and a third heat exchanger. The second circuit includes a second pump for circulating a second medium therethrough, a second heat exchanger and a fourth heat exchanger. Additionally, the system includes a thermoelectric module having a first surface in thermal contact with the first heat exchanger and a second surface in thermal contact with the second heat exchanger. 
     The system operates in a heating mode, a cooling mode and a demisting mode. In the heating mode, an electrical current is passed through the thermoelectric module so that the second side of the thermoelectric module warms the second medium through the second heat exchanger. An engine, which is operatively engaged with the first circuit, warms the first medium. As the first and second mediums are warmed, the first and second pumps circulate the mediums through the third and fourth heat exchangers respectively. 
     The third and fourth heat exchangers are located near a blower. Generally, the third heat exchanger is located between the blower and the fourth heat exchanger such that blower will move air through the third heat exchanger before moving air through the fourth heat exchanger. After the air passes through the third and fourth heat exchangers, the air enters the passenger compartment of the automobile. 
     In the cooling mode, an electrical current is passed through the thermoelectric module so that the second side of the thermoelectric module cools the second medium through the second heat exchanger. The second pump circulates the cooler second medium through the fourth heat exchanger. In this mode, the first medium is directed through the second bypass line by the second double switching valve. By utilizing the second bypass line, the heated first medium is either reduced or not directed through the third heat exchanger. The air passing through the third heat exchanger will not be heated or will be heated by a reduced amount, while the air passing through the fourth heat exchanger will be cooled. 
     In the demisting mode, the air provided by the blower is first cooled before it is heated and/or passed to the passenger compartment. By initially cooling the air, moisture can be removed from the air via condensation. One way to accomplish this is through the addition of another heat exchanger placed between the blower and the third heat exchanger. Through the use of bypass lines and double switching valves, the cooled second medium will be directed to the heat exchanger placed between the blower and the third heat exchanger. The air provided by the blower will first be cooled by the heat exchanger placed between the blower and the third heat exchanger before the air is heated by the third heat exchanger. Alternatively, the third heat exchanger  32  may be split into multiple portions, such that some portions may heat and other portions may cool. 
     Another way of accomplishing demisting is through the addition of multiple bypass lines and double switching valves. The bypass lines and double switching valves will direct the first medium to the fourth heat exchanger and will direct the second medium to the third heat exchanger. By directing the cooler second medium to the third heat exchanger and the warmer first medium to the fourth heat exchanger, the air provided by the blower will first be cooled by the third heat exchanger before it is warmed by the fourth heat exchanger. Other alternative fluid paths and other heat exchanger configurations may also be utilized. 
     These and other advantages, features and embodiments of the invention will become apparent from the drawings, detailed description and claims which follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an HVAC unit embodying the principles of the present invention; 
         FIG. 2  is a block diagram of a second embodiment of an HVAC unit according to the principles of the present invention and including a supplemental heating source and cooling source; 
         FIG. 3  is a block diagram of a third embodiment of an HVAC unit with according to the principles of the present invention and including a demisting heat exchanger; and 
         FIG. 4  is a block diagram of a fourth embodiment of the HVAC unit with bypass lines for transferring first and second mediums between a third heat exchanger and a fourth heat exchanger. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , the various components of a HVAC unit  10  are shown. The HVAC unit  10  includes a first circuit  12  having a first pump  14 , a second circuit  16  having a second pump  18 , and a thermoelectric module  20  having a first surface  22  and a second surface  24  in thermal communication with the first and second circuits  12 ,  16 , respectively. The first pump  14  circulates a first medium through the first circuit, and the second pump  18  circulates a second medium through the second circuit  16 . 
     In the context of this description, the term “pump” is used in its broad sense of its ordinary and customary meaning and further includes any conventional pump, JxB (J Cross B) pump, electrostatic pump, centrifugal pump, positive displacement pump, gear pump, peristaltic pump or any other medium moving device or combination thereof that is known or later developed. 
     Generally, the first and second mediums are a liquid having a mix of water and glycol. Alternatively, the first and/or second mediums may be a fluid, gas or multipurpose solid-liquid convection medium. 
     In the context of this description, the term “thermoelectric module” is used in a broad sense of its ordinary and customary meeting, which is (1) conventional thermoelectric modules, such as those produced by Marlow Industries, Inc. of Dallas, Tex., (2) quantum tunneling converters, (3) thermionic modules, (4) magneto caloric modules, (5) elements utilizing one, or any bi-combination of, thermoelectric, magneto caloric, quantum tunneling and thermionic effects, (6) acoustic heating mechanisms, (7) thermoelectric systems described is U.S. Pat. No. 6,539,725 to Bell, (8) any other sold state heat pumping device (9) any combination, array, assembly and other structure of (1) through (8) above. 
     In thermal communication with a first heat exchanger  26  is the first surface  22  of the thermoelectric module  20 . The first heat exchanger  26  is in turn in thermal communication with the first medium of the first circuit  12 . In thermal communication with a second heat exchanger  28  is the second surface  24  of the thermoelectric module  20 . This second heat exchanger  28  is likewise in thermal communication with the second medium of the second circuit  16 . 
     Preferably, an internal combustion engine  30  is operatively engaged with the first circuit  12  such that the first medium is circulated by the first pump  14  and is used to cool the engine  30 . Alternatively, the engine  30  can be any heat generating source that is known or later developed. 
     Connected to the first circuit  12  is a third heat exchanger  32  and connected to the second circuit  16  is a fourth heat exchanger  34 , both of which are used to condition (heat or cool) air to be provided to the passenger compartment. Accordingly, proximate to the third and fourth heat exchangers  32 ,  34  is a blower  36 . As indicated by the arrow  38 , the blower  36  moves air through the third heat exchanger  32  and the fourth heat exchanger  34  before moving the air into the passenger compartment of an automobile. The blower  36  may be a conventional blower, fan, electrostatic blower, centrifugal blower or any air moving system that is known or later developed. 
     Preferably, the first circuit  12  has a fifth heat exchanger  40 , generally a radiator, for cooling the first medium within the first circuit  12 . Alternatively, the fifth heat exchanger  40  may be a heat sink or any device that absorbs or rejects heat including the traditional radiator, frame or other vehicle parts. A first bypass line  42  and a first double switching valve  44  are connected to the first circuit  12  such that the first double switching valve  44  can selectively direct the first medium through the first bypass line  42  instead of the fifth heat exchanger  40 . By circulating the first medium through the first bypass line  42  instead of the fifth heat exchanger  40 , the first medium can be heated more quickly by the engine  30  because the fifth heat exchanger  40  will not have an opportunity to cool the first medium. This is beneficial when the first medium is very cold. 
     In the context of this description, the term “double switching valve” is used in its broad sense of its ordinary and customary meaning and further includes any valve or medium directing device or combination thereof that is known or later developed. 
     The first circuit  12  may also have a second bypass line  46  and a second double switching valve  48 . The second double switching valve  48  can selectively direct the first medium through the second bypass line  46  (during cooling mode operation) instead of through a section of the first circuit  12  that includes the third heat exchanger  32 . By circulating the first medium through the second bypass line  46 , the first medium will be unable to transfer heat to the third heat exchanger  32 , and thus air provided by the blower  36  will not be heated by the third heat exchanger  32 . Additionally, the temperature of the first surface  22  of the thermoelectric module  20  will not be affected by the first medium. This can be advantageous when the HVAC unit  10  is cooling the passenger compartment of the automobile. 
     The HVAC unit  10  operates in either a heating mode or a cooling mode. In the heating mode, the direction of the current flowing through the thermoelectric module  20  will be such that the first surface  22  cools and the second surface  24  warms. The second surface  24  will pass the heat through the second heat exchanger  28  and to the second medium. As the second medium is passed through the fourth heat exchanger  34 , the air provided by the blower  36  is heated thereby. This augments any heating of the air by the third heat exchanger  32 . 
     As the engine  30  warms up, it heats the first medium that will be circulated through the third heat exchange  32  and the first heat exchanger  26 . The heat of the first medium is passed through the first heat exchanger  26  to first surface  22  of the thermoelectric module  20 . By warming the first surface  22  of the thermoelectric module  20 , the difference in temperature between the first surface  22  and the second surface  24  will be minimized, allowing the thermoelectric module  20  to operate more efficiently. 
     In a cooling mode, the direction of the current flowing through the thermoelectric module  20  will be such that the second surface  24  of the thermoelectric module  20  cools and the first surface  22  of the thermoelectric module  20  warms. The second surface  24  will cool the second medium via the second heat exchanger  28  and, as the cooled second medium is passed through the fourth heat exchanger  34 , the air, provided by the blower  36 , is cooled before entering the passenger compartment. 
     In this mode, the first medium is directed through the second bypass line  46  by the second double switching valve  48 . By utilizing the second bypass line  46 , the heated first medium is not directed through the third heat exchanger  32  and subsequently the first heat exchanger  26  and the first surface  22  of the thermoelectric module  20 . The temperature of the first surface  22  of the thermoelectric module  20  therefore not heated, remaining closer in temperature to the second surface  24 . As stated before, by having a low temperature differential between the first surface  22  and a second surface  24  of the thermoelectric module  20 , the thermoelectric module will operate more efficiently. Additionally, because the third heat exchanger  32  will not be heated by the first medium, air passing through the third heat exchanger  32  will not be heated. 
     Generally, the first circuit  12  will have a branch circuit  50  having its own pump  52 , valve  54  and heat exchanger  56 . The branch or third circuit  50  is used to supplement the cooling of a portion of the first medium and the first surface  22 . For example, when the valve  54  is configured to allow a portion of the first medium to flow through the branch circuit  50 , the heat exchanger  56  of the branch circuit will aid in the cooling of the first medium. It is noted that during this such operation, valve  48  will also be directing a portion of the first medium across bypass line  46 . When the valve  54  is configured to prevent the first medium from circulating through the branch circuit  50 , the heat exchanger  56  will not supplement the cooling of the first medium. 
     Referring now to  FIG. 2 , another HVAC unit  10 ′ is shown. This unit  10 ′ is the same as that discussed previously, except, the first circuit  12  includes a heat generating system  60  located between the engine  30  and valve  48  and the third circuit  50  includes a cold generating system  61  located between the heat exchanger  56  and the first heat exchanger  26 . A bypass line  58  and associated double switching valve  62  are also provided so that the first medium may be bypassed around the heat generating system  60 , if desired. The heat generating system  60  may be one or more of any system that generates, captures or releases heat, such as a battery, an electronic device, an internal combustion engine, an exhaust of a vehicle, a heat sink, a heat storage system such as a phase change material, a positive temperature coefficient device or any heat generating system that is known or later developed. The third double switching valve  62  will direct the first medium through either the third bypass line  58  or the heat generating system  60 . By circulating the first medium through the heat generating system  60 , the first medium can be heated more quickly than by the engine  30  alone. 
     A bypass line  59  and associated double switching valve  63  are also provided so that the first medium may be bypassed around the cold generating system  61 , if desired. The cold generating system  61  may be one or more of any system that generates, captures or releases cold, such as a thermoelectric module, a heat sink, a cold storage system such as a phase change material or any cold generating system that is later developed. The double switching valve  63  will direct the first medium through either the bypass line  59  or the cold generating system  61 . By circulating the first medium through the cold generating system  61 , the first medium can be cooled more quickly than by the heat exchanger  56  alone. 
     Referring now to  FIG. 3 , another embodiment of a HVAC unit  10 ″ is shown. This unit  10 ″ is substantially the same as that discussed above and shown in  FIG. 1 . However, a demisting heat exchanger  64  is provided in the second circuit  16  as a bypass, via double switching valve  66 , around the fourth heat exchanger. Thus, the demisting double switching valve  66  will selectively direct the second medium through the demisting heat exchanger  64  instead of the fourth heat exchanger  34 . As indicated by the arrow  38 , the blower  36  will blow air first through the demisting heat exchanger  64 . This initial cooling of the air removes moisture from the air via condensation. 
     After the air is initially cooled, the air may be cooled or heated by the third heat exchanger  32 . The valves  67 ,  69  and  71  will direct the first medium through either first circuit  12 , where it is warmed by the engine  30 , or through the third circuit  50 , where it is cooled by the heat exchanger  56 , and then through the third heat exchanger  32 . Alternatively, the double switching valve  48  may prevent the first medium from traveling through the third heat exchanger  32 , thereby preventing any heating or cooling the air by the third heat exchanger  32 . 
     Referring now to  FIG. 4 , another embodiment of the HVAC unit  10 ′″ is shown. The HVAC unit  10 ′″ is substantially the same as the discussed above and shown in  FIG. 1 . However, a fourth bypass line  68  and a fifth bypass line  70  circulate the second medium to the third heat exchanger  32  and a sixth bypass line  76  and a seventh bypass line  78  circulate the first medium to the fourth heat exchanger  34 . 
     A fourth double switching valve  72  will direct the second medium from the second circuit  16 , through the fourth bypass line  68 , and to the third heat exchanger  32 . A fifth double switching valve  74  will direct the second medium from the third heat exchanger  32 , through the fifth bypass line  70 , and to the second circuit  16 . 
     A sixth double switching valve  80  will direct the first medium from the first circuit  12 , through the sixth bypass line  76 , and to the fourth heat exchanger  34 . A seventh double switching valve  82  will direct the first medium from the fourth heat exchanger  34 , through the seventh bypass line  78 , and to the first circuit  12 . 
     By directing the cooler second medium and warmer first medium through the third heat exchanger  32  and the fourth heat exchanger  34  respectively, the third heat exchanger  32  will cool air blown by the blower  36  before the air is heated by the fourth heat exchanger  34 . The initial cooling of the air removes moisture from the air via condensation. 
     Additionally, an eighth double switching valve  84  may be connected to the second bypass line  46  and the first circuit  12 . The eighth double switching valve  84  will direct the first medium through either the second bypass line  46  or the first heat exchanger  26 . By circulating the first medium through the second bypass line  46 , the first heat exchanger  26  will not be in thermal communication with the warmer first medium. This can be advantageous when the HVAC unit  10  is in the cooling mode. The heat contained within the first medium will be unable to transfer heat to the first surface  22  of the thermoelectric module  20 . By minimizing the temperature differential between the first surface  22  and the second surface  24  of the thermoelectric module  20 , the thermoelectric module  20  will operate more efficiently. 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles of this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.