Abstract:
A watercraft engine fuel cooling system that cools a fuel vapor separator through a detachable heat exchanger. The detachable heat exchanger allows for inexpensive replacement of the detachable heat exchanger if the heat exchanger should become damaged from corrosion. The detachable heat exchanger can transfer the heat from the vapor separator through a water cooling jacket, a thermoelectric element, or through fins to the surrounding air. The transfer of heat from the fuel vapor separator allows the fuel to be kept within a predetermined fuel temperature range.

Description:
PRIORITY INFORMATION  
         [0001]    This application is based on and claims priority to Japanese Patent Application No. 2003-140077, filed May 19, 2003, the entire contents of which is hereby expressly incorporated by reference.  
         BACKGROUND OF THE INVENTIONS  
         [0002]    1. Field of the Inventions  
           [0003]    The present inventions relate generally to a fuel cooling system for an outboard motor, and more particularly to a detachable fuel cooling system for a vapor separator.  
           [0004]    2. Description of the Related Art  
           [0005]    In the interest of improving engine performance and particularly fuel efficiency and exhaust emission control, many types of engines now employ a fuel injection system for supplying fuel to the engine. In these systems, fuel usually is injected into an air induction device by a fuel injector. This type of fuel injection has the advantages of permitting the amount of fuel delivered for each cycle of the engine to be precisely adjusted. In addition, by utilizing the fuel injection system, it is possible to maintain the desired fuel air ratio under a wide variety of engine running condition.  
           [0006]    An amount of the fuel injected by the fuel injector is usually controlled by a control device in response to the engine running conditions. The fuel is delivered to the fuel injector by a fuel pump under a certain fixed pressure and the duration for injection per unit time, i.e., a duty ratio, is controlled by the control device so that any required amount can be metered. Strict control of the fuel amount is quite important for stable operations of the engine.  
           [0007]    Some engines for outboard motors employ such a fuel injection system. The fuel injection system generally includes, other than the fuel injector, a main fuel tank disposed on a hull of the associated watercraft for storing fuel and a fuel reservoir attached on the engine for temporarily storing the fuel. The fuel in the main fuel tank is supplied to the fuel reservoir through a fuel supply conduit and the fuel in the fuel reservoir, in turn, is delivered to the fuel injector through another fuel supply conduit. The excess fuel that has not been injected by the fuel injector is returned to the fuel reservoir through a return conduit.  
           [0008]    The engine is, due to being employed for outboard motors, operated quite often in a high speed and high load. The engine, thus, produces much heat under this running condition. In addition, the engine is generally enclosed in a protective cowling assembly and the heat accumulates within the cowling. The ambient air around the engine, as a matter of course, is heated. The fuel supply conduits, at least in part, and the fuel return conduit extend within the protective cowling assembly and thus tend to absorb some heat from the engine.  
           [0009]    Under some circumstances, bubbles or vapor can be formed in the fuel and interfere and degrade the strict control of the fuel amount injected during each duty cycle. Vapor lock may even occur in the fuel supply and/or fuel return conduits. If this happens, the fuel is no longer be supplied or returned to the fuel injector or fuel reservoir and the engine consequently stalls.  
         SUMMARY OF THE INVENTIONS  
         [0010]    Watercraft engines typically incorporate an engine cooling system and a fuel system that includes a vapor separator. Within the engine cooling system is commonly a cooling subsystem that cools the vapor separator. Due to the heat generated by the engine and the compact environment of watercraft engine compartments, a vapor separator cooler can be used to keep the fuel within a predetermined fuel temperature.  
           [0011]    Using a cooling system to cool the vapor separator can lead to corrosion and an eventual replacement of the entire vapor separator. Replacement of the entire vapor separator can be costly, inconvenient, and time consuming.  
           [0012]    One aspect of at least one of the inventions disclosed herein includes the realization that certain problems associated with corrosion of a vapor separator caused by water-cooling can be overcome by forming the cooling jacket separate from the vapor separator and connecting the separate pieces for thermal communication during operation. For example, a cooling jacket for the vapor separator can be formed of a heat exchanger device with at least one surface configured to thermally communicate with an outer surface of the vapor separator. As such, the pieces of the vapor separator and the cooling jacket can be disassembled and cleaned, thereby allowing the removal and monitoring of corrosion.  
           [0013]    In accordance with an embodiment of at least one of the inventions disclosed herein, an engine comprises an engine body defining at least one combustion chamber. A fuel system is configured to provide fuel for combustion in the combustion chamber, the fuel system including a vapor separator. Additionally, a heat exchanger is disposed in thermal communication with the vapor separator and configured to be detachable from the vapor separator.  
           [0014]    In accordance with another embodiment of at least one of the inventions disclosed herein, a watercraft propulsion system comprises an engine including an engine body defining at least one combustion chamber. A fuel system includes a vapor separator, the vapor separator including a vapor separator tank. Additionally, a detachable heat exchanger includes a heat exchanger cooling system configured to transfer heat away from the vapor separator tank.  
           [0015]    In accordance with a further embodiment of at least one of the inventions disclosed herein, an engine comprises an engine body defining at least one combustion chamber. A fuel system is configured to provide fuel for combustion in the combustion chamber, the fuel system including a vapor separator. Additionally, a heat exchanger is disposed in thermal communication with the vapor separator, the heat exchanger including means for detaching the heat exchanger from the vapor separator. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The foregoing features, aspects, and advantages of the present inventions will now be described with reference to the drawings of a preferred embodiment that is intended to illustrate and not to limit the inventions. The drawings comprise nine figures in which:  
         [0017]    [0017]FIG. 1 is a side elevational view of an outboard motor configured in accordance with a preferred embodiment, with an associated watercraft partially shown in section;  
         [0018]    [0018]FIG. 2 is a top view of an outboard motor configured in accordance with a preferred embodiment, with various parts sectioned to show greater detail;  
         [0019]    [0019]FIG. 3 is a schematic diagram of the fuel system and its control parameters including a fuel tank, fuel pumps, a vapor separator and a cooling body of water,  
         [0020]    [0020]FIG. 4 a  is a side elevational sectioned view of the vapor separator including a high pressure fuel pump and a vapor separator cooling system configured in accordance with a preferred embodiment;  
         [0021]    [0021]FIG. 4 b  is a top cross sectional view of the vapor separator taken along the line B-B in FIG. 4 a  in accordance with a preferred embodiment;  
         [0022]    [0022]FIG. 5 a  is a side elevational sectioned view of the vapor separator including a high pressure fuel pump and another vapor separator cooling system configured in accordance with another preferred embodiment;  
         [0023]    [0023]FIG. 5 b  is a top cross sectional view of the vapor separator taken along the line C-C in FIG. 5 a  in accordance with another preferred embodiment;  
         [0024]    [0024]FIG. 6 a  is a side elevational sectioned view of the vapor separator including a high pressure fuel pump and another vapor separator cooling system configured in accordance with another preferred embodiment, and  
         [0025]    [0025]FIG. 6 b  is a top cross sectional view of the vapor separator taken along the line D-D in FIG. 6 a  in accordance with another preferred embodiment; 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    With reference to FIGS. 1-5, an outboard motor  10  includes a drive unit  12  and a bracket assembly  14 . The bracket assembly  14  attaches the drive unit  12  to a transom  16  of an associated watercraft  18  and supports a marine propulsion device such as propeller  58  in a submerged position relative to a surface of a body of water.  
         [0027]    As used to this description, the terms “forward,” “forwardly,” and “front” mean at or to the side where the bracket assembly  14  is located, unless indicated otherwise or otherwise readily apparent from the context use. The terms “rear,” “reverse,” “backwardly,” and “rearwardly” mean at or to the opposite side of the front side.  
         [0028]    The illustrated drive unit  12  includes a power head  20  mounted on top of drive unit  12 . The drive unit  12  also includes a drive shaft housing  24  and the lower unit  26 . The power head  20  includes an internal combustion engine  28  within a protective cowling assembly  30 , which can be made of plastic. The protective cowling assembly  30  typically defines a generally closed cavity  32  in which the engine  28  is disposed. The engine  28  is thereby is generally protected by the cowling assembly  30  from environmental elements.  
         [0029]    The protective cowling assembly  30  includes a top cowling member  34  and a bottom cowling member  36 . The top cowling member  34  can be detachably affixed to the bottom cowling member  36  by a suitable coupling mechanism to facilitate access to the engine and other related components.  
         [0030]    The bottom cowling member  36  has an opening for which an upper portion of an exhaust guide member  38  extends. The exhaust guide member  38  advantageously is made of aluminum alloy and is affixed to the top of the driveshaft housing  24 . The bottom cowling member  36  and the exhaust guide member  38  together generally form a tray. The engine  28  is placed on to this tray and can be connected to the exhaust guide member  38 . The exhaust guide member  38  also defines an exhaust discharge passage through which burnt charges (e.g., exhaust gases) from the engine  28  pass.  
         [0031]    The engine  28  in the illustrated embodiment preferably operates on a four-cycle combustion principle. With reference now to FIG. 2, the engine embodiment illustrated is a DOHC six-cylinder engine having a V-shaped cylinder block  40 . The cylinder block  40  thus defines two cylinder banks, which extend generally side by side with each other. In the illustrated arrangement, each cylinder bank has three cylinder bores such that the cylinder block  40  has six cylinder bores in total. The cylinder bores of each bank extend generally horizontally and are generally vertically spaced from one another. This type of engine, however, merely exemplifies one type of engine. Engines having other numbers of cylinders, having other cylinder arrangements (in line, opposing, W, etc.), and operating on other combustion principles (e.g., crankcase compression, two-stroke, diesel, or rotary) can be used in other embodiments.  
         [0032]    As used in this description, the term “horizontally” means that members or components extend generally parallel to the water surface (i.e., generally normal to the direction of gravity) when the associated watercraft  18  is substantially stationary with respect to the water surface and when the drive unit  12  is not tilted (i.e., as shown in FIG. 1). The term “vertically” in turn means that proportions, members or components extend generally normal to those that extend horizontally.  
         [0033]    A movable member, such as a reciprocating piston, moves relative to the cylinder block  40  in a suitable manner. In the illustrated arrangement, a piston (not shown) reciprocates within each cylinder bore. Because the cylinder block  40  is split into the two cylinder banks, each cylinder bank extends outward at an angle to an independent first end in the illustrated arrangement. A pair of cylinder head members  42  are fixed to the respective first ends of the cylinder banks to close those ends of the cylinder bores. The cylinder head members  42  together with the associated pistons and cylinder bores provide six combustion chambers (not shown). Of course, the number of combustion chambers can vary, as indicated above. Each of the cylinder head members  42  is covered with the cylinder head cover member  44 .  
         [0034]    A crankcase member  46  is coupled with the cylinder block  40  and a crankcase cover member  48  is further coupled with a crankcase member  46 . The crankcase member  46  and a crankcase cover member  48  close the other end of the cylinder bores and, together with the cylinder block  40 , define the crankcase chamber.  
         [0035]    The crankshaft  50  extends generally vertically through the crankcase chamber and journaled for rotation about a rotational axis by several bearing blocks. Connecting rods couple the crankshaft  50  with the respective pistons in any suitable manner. Thus, a reciprocal movement of the pistons rotates the crankshaft  50 .  
         [0036]    With reference again to FIG. 1, the driveshaft housing  24  depends from the power head  20  to support a drive shaft  52 , which is coupled with crankshaft  50  and which extends generally vertically through driveshaft housing  24 . The driveshaft  52  is journaled for rotation and is driven by the crankshaft  50 .  
         [0037]    The lower unit  26  depends from the driveshaft housing  24  and supports a propulsion shaft  54  that is driven by the driveshaft  52  through a transmission unit  56 . A propulsion device is attached to the propulsion shaft  54 . In the illustrated arrangement, the propulsion device is the propeller  58  that is fixed to the transmission unit  56 . The propulsion device, however, can take the form of a dual counter-rotating system, a hydrodynamic jet, or any of a number of other suitable propulsion devices.  
         [0038]    Preferably, at least three major engine portions  40 ,  42 ,  44 ,  46 , and  48  are made of aluminum alloy. In some arrangements, the cylinder head cover members  44  can be unitarily formed with the respective cylinder members  42 . Also, the crankcase cover member  48  can be unitarily formed with the crankcase member  46 .  
         [0039]    The engine  28  also comprises an air intake system  72 . The air intake system  72  guides air from within the cavity  32  to the combustion chambers. The air intake system  72  shown comprises six intake passages  74  and a pair of intake silencers  76 . In the illustrated arrangement, each cylinder bank communicates with three intake passages  74  and one intake silencer  76 .  
         [0040]    The most downstream portions of the intake passages  74  are defined within the cylinder head member  42  as inner intake passages. The inner intake passages communicate with the combustion chambers through intake ports, which are formed at inner surfaces of the cylinder head members  42 . Typically, each of the combustion chambers has one or more intake ports. Intake valves are slidably disposed at each cylinder head member  42  to move between an open position and a closed position. As such, the valves act to open and close the ports to control the flow of air into the combustion chamber. Biasing members, such as springs, are used to urge the intake valves toward their respective closed positions by acting between a mounting boss formed on each cylinder head member  42  and a corresponding retainer that is affixed to each of the valves. When each intake valve is in the open position, the inner intake passage thus associated with the intake port communicates with the associated combustion chamber.  
         [0041]    Other portions of the intake passages  74 , which are disposed outside of the cylinder head members  42 . In the illustrated arrangement, each intake passage  74  comprises a throttle body  80 , in which a throttle valve assembly  82  is positioned. The respective intake passage  74  extends forwardly alongside surfaces of the engine  28  on both the port side and the starboard side from the respective cylinder head members  42  to the front of the crankcase cover member  48 . The intake passage  74  on the same side extend generally and parallel to each other and are vertically spaced apart from one another.  
         [0042]    Each throttle valve assembly  82  preferably includes a throttle valve. Preferably, the throttle valves are butterfly valves that have valve shafts journaled for pivotal movement about generally vertical axis. In some arrangements, the valve shafts are linked together and are connected to a control linkage. The control linkage is connected to an operational member, such as a throttle lever, that is provided on the watercraft or otherwise proximate the operator of the watercraft  18 . The operator can control the opening degree of the throttle valves in accordance with operator request through the control linkage. That is, the throttle valve assembly  82  can measure or regulate amounts of air that flow through intake passages  74  through the combustion chambers in response to the operation of the operational member by the operator. Normally, the greater the opening degree, the higher the rate of airflow and the higher the engine speed.  
         [0043]    The air within the closed cavity  32  is drawn into the intake silencer  76  and then enters the outer intake passages  74 . The air passes through the outer intake passage  74  and the throttle valve assembly  82  regulates the level of airflow.  
         [0044]    The engine  28  further includes an exhaust system that routes burnt charges, i.e., exhaust gases, to a location outside of the outboard motor  10 . Each cylinder head member  42  defines a set of inner exhaust passages that communicate with the combustion chambers to one or more exhaust ports which may be defined at the inner surfaces of the respective cylinder head members  42 . The exhaust ports can be selectively opened and closed by exhaust valves. The construction of each exhaust valve and the arrangement of the exhaust valves are substantially the same as the intake valve and the arrangement thereof, respectively. Thus, further description of these components is deemed unnecessary.  
         [0045]    Exhaust manifolds preferably are defined generally vertically with the cylinder block  40  between the cylinder bores of both the cylinder banks. The exhaust manifolds communicate with the combustion chambers through the inner exhaust passages and the exhaust ports to collect the exhaust gas therefrom. When the exhaust ports are opened, the combustion chambers communicate with the exhaust discharge passage through the exhaust manifolds.  
         [0046]    In the embodiment of FIG. 1, the driveshaft housing  24  defines an internal section of the exhaust system that leaves the majority of the exhaust gases to the lower unit  26 . The internal section includes an idle discharge portion that extends from a main portion of the internal section to discharge idle exhaust gases directly to the atmosphere through a discharge port that is formed on a rear surface of the driveshaft housing  24 .  
         [0047]    Lower unit  26  also defines an internal section of the exhaust system that is connected with the internal exhaust section of the driveshaft housing  24 . At engine speeds above idle, the exhaust gases are generally discharged to the body of water surrounding the outboard motor  10  through the internal sections and then a discharge section defined within the hub of the propeller  58 .  
         [0048]    A valve cam mechanism preferably is provided for actuating the intake and exhaust valves in each cylinder bank. In the embodiment shown, the valve cam mechanism includes second rotatable members such as a pair of camshafts  96  per cylinder bank. The camshafts  96  typically comprise intake and exhaust camshafts that extend generally vertically and are journaled for rotation between the cylinder head members  42  and the cylinder head cover members  44 . The camshafts  96  have cam lobes  97  to push valve lifters that are fixed to the respective ends of the intake and exhaust valves in any suitable manner. Cam lobes repeatedly push the valve lifters in a timely manner, which is in proportion to the engine speed. The movement of the lifters generally is timed by rotation of the camshaft  96  to appropriately actuate the intake and exhaust valves.  
         [0049]    The illustrated engine  28  further includes indirect, port or intake passage fuel injection. In a preferred embodiment, the engine  28  comprises fuel injection. The illustrated fuel injection system shown includes six fuel injectors  90  with one fuel injector allotted to each one of the respective combustion chambers. The fuel injectors  90  preferably are mounted on the throttle body  66  of the respective banks.  
         [0050]    Each fuel injector  90  has advantageously an injection nozzle directed downstream within the associated intake passage  74 . The injection nozzle preferably is disposed downstream of the throttle valve assembly  82 . The fuel injectors  90  spray fuel into the intake passages  74  under control of an electronic control unit (ECU) (not shown). The ECU controls the initiation, timing and the duration of the fuel injection cycle of the fuel injector  90  so that the nozzle spray a desired amount of fuel for each combustion cycle.  
         [0051]    With reference to FIG. 3, a vapor separator  108  preferably is in fluid communication with a fuel tank  113  and a fuel conduit, and can be disposed along the intake passages  74  in one arrangement. The vapor separator  108  separates vapor from the fuel and can be mounted on the engine  28 . The vapor separator  108  along with a vapor separator cooling system  109  is described in greater detail below.  
         [0052]    The fuel injection system can employ one or a plurality of fuel pumps to deliver the fuel to the vapor separator  108  and to send out the fuel therefrom. More specifically, in the illustrated arrangement, a lower pressure pump  110  pressurizes the fuel toward the vapor separator  108  and the high pressure pump  111 , which is disposed within the vapor separator  108 , pressurizes the fuel passing out of the fuel separator  108 .  
         [0053]    A vapor delivery conduit  112  couples the vapor separator  108  with at least one of the intake silencers  76  or at least one of the intake passages  74 . The vapor removed from the fuel supply by the vapor separator  108  thus can be delivered to the intake silencer  76  or the intake passage  24  for delivery to the combustion chambers with the combustion air. In other applications, the engine  28  can be provided with a ventilation system arranged to send lubricant vapor to the plenum chamber(s). In such applications, the fuel vapor also can be sent to the plenum chambers via the ventilation system.  
         [0054]    The engine  28  further includes an ignition system. Each combustion chamber is provided with a spark plug (not shown), advantageously disposed between the intake and exhaust valves. Each spark plug has electrodes that are exposed in the associated combustion chamber. The spark plugs generate a spark between the electrodes to ignite an air/fuel charge in the combustion chamber according to desired ignition timing maps or other forms of controls.  
         [0055]    Generally, during an intake stroke, air is drawn into the combustion chambers through the air intake passages  74  and fuel is mixed with the air by the fuel injectors  90 . The mixed air/fuel charge is introduced to the combustion chambers. The mixture is then compressed during the compression stroke. Just prior to a power stroke, the respective spark plugs ignite the compressed air/fuel charge in the respective combustion chambers. The air/fuel charge thus rapidly burns during the power stroke to move the pistons. The burnt charge, i.e., exhaust gases, then is discharged from the combustion chambers during an exhaust stroke.  
         [0056]    The illustrated engine further comprises a lubrication system to lubricate the moving parts within the engine  28 . The lubrication system is a pressure fed system where the correct pressure is important to adequately lubricate the bearings and other rotating surfaces. The lubrication oil is taken from an oil reservoir (not shown) and delivered under pressure throughout the engine to lubricate the internal moving parts.  
         [0057]    The engine  28  may include other systems, mechanisms, devices, accessories, and components other than those described above such as, for example, a cooling system. The crankshaft  50  through a flexible transmitter, such as a timing belt can directly of indirectly drive those systems, mechanisms, devices, accessories, and components.  
         [0058]    With reference to FIG. 3, a schematic diagram illustrates a fuel injection system including the vapor separator  108  and an open loop cooling system to cool the engine  28  and the vapor separator  108 . Fuel is initial drawn by the low-pressure fuel pump  110  from the fuel tank  113  through a fuel tank supply conduit  116  and passes through a fuel filter  118 . The fuel is regulated according to a predetermined amount of fuel measured by a float mechanism  120  before entering a vapor separator tank  124 . The fuel is delivered from the vapor separator tank  124  by the high-pressure fuel pump  111  through fuel delivery lines  126  to each fuel injector  90 . A fuel pressure regulator  128  regulates the fuel pressure inside the fuel delivery lines  126 .  
         [0059]    Fuel inside the vapor separator tank  124  is kept at a predetermined temperature through the vapor separator cooling system  114 . The vapor separator cooling system  114  can include a detachable heat exchanger  132  that is configured to be detachable from the vapor separator tank  124 . When brought into thermal communication with the vapor separator tank  124 , the heart exchanger  132  transfers heat away from the vapor separator tank  124 . The heat exchanger  132  can use cooling water or other fluids for cooling purposes.  
         [0060]    The cooling water used in the heat exchanger  132  can be directed to the heat exchanged  132  through an open-loop cooling system or a closed-loop cooling system. The cooling system  114  can be a separate cooling system designed only to specifically cool the vapor separator tank  124  or the cooling system  114  can be part of another cooling system of the outboard motor  10 . For example, the cooling system  114  can be a subpart of a cooling system for cooling the engine  28 . Such a cooling system can be an open or closed loop type.  
         [0061]    The cooling system  114  can include a heat transfer layer  134  disposed between the heat exchanged  132  and the vapor separator tank  124 . The heat transfer later can be configured to allow heat to be effectively transferred from the vapor separator tank  124  to the heat exchanger  132 . The heat transfer layer  134  can be made from a material such as, but not limited to copper, silicon grease, or any material with a high thermal conductivity.  
         [0062]    With further reference to FIG. 3, a water pump  136  is configured to pump cooling water from an outside source, for example a lake of an ocean, and to deliver the cooling water to the engine  28 . Cooling water is delivered to the heat exchanger  132  though a heat exchanger supply conduit  140  and to the engine  28  through other conduits. After transferring heat away from the vapor separator tank  124  through the heat transfer layer  134  and the heat exchanger  132 , the water is returned to the body of water through a cooling water return conduit  142 .  
         [0063]    [0063]FIG. 4 a  illustrates a cross sectional side view of a preferred embodiment of the vapor separator  108  and the vapor separator cooling system  114 . The detachable heat exchanger  132  is attached to the vapor separator tank  124  through at least one bolt  146  (FIG. 4 b ). The detachable heat exchanger  132  can also be attached to the vapor separator tank  124  by other attachment systems including, but not limited to, screws, rivets, and/or an epoxy.  
         [0064]    The detachable heat exchanger  132  includes a body  153 , a coolant supply passage  144 , a primary cooling passage  148 , a plurality of secondary passages  150 , and a coolant exiting passage  152 . In this embodiment, the secondary passages are defined, in part, by a recess in the body  153  of the heat exchanger  132  and includes a plurality of ridges extending along one side of the recess. The primary passage  148  is defined by a tubular member extending into the recess. The tubular member is shorter than the recess and thus defines a spillway between the primary passage  148  and the secondary passages  150 .  
         [0065]    During operation, coolant flows into the supply passage  144 , into the primary cooling passage  148  until it reaches the top thereof. Then the coolant flows out of the upper end of the primary passage  148  and spills into the secondary passages  150 . As such, heat from the vapor separator tank  124  is transferred to the coolant. The numerous secondary cooling passages  150  provide an increase in surface area to allow more coolant to come in contact with the surface of the secondary-cooling passages  150 . This provides an additional advantage in that more coolant coming in contact with more surface area of the secondary cooling passages  150  allows the detachable heat exchanger  132  to remove more heat from the vapor separator tank  124  through the heat transfer layer  134 . The coolant exits the detachable heat exchanger  132  through a coolant exiting passage  152  that connects to the coolant water return line  142 .  
         [0066]    [0066]FIG. 5 a  illustrates a cross sectional side view of a modification of the vapor separator cooling system  114 , and is identified generally by the reference number  114 A. Components of the cooling system  114 A that correspond to the respective components of the cooling system  114  have been identified with the same reference numerals, except that a letter “A” has been added thereto.  
         [0067]    With reference to FIG. 5 b , the primary cooling passage  148 A extends upwardly from the supply passage  144 A. At the top of the primary cooling passage  148 A, the heat exchanger  132 A includes a passage leading to the secondary cooling passage  150 A. In the illustrated embodiment, the primary and secondary passages  148 A,  150 A, are separated by a dividing wall  151 , however, other constructions can be used. The coolant exiting passage  152 A connects the secondary passage  150 A with the return line  142 .  
         [0068]    The heat exchanger  132 A can also be defined by two or more separate pieces. For example, the primary and secondary cooling passages  148 A,  150 A can be defined initially by open channels or grooves defined in a body member  153 , the open portions being closed by a detachable cover member  154 . In this embodiment, the bolt  146 A can hold the detachable cover  154 . Optionally, a gasket or o-ring  156  can be used to seal the cover  154  to the body  153 .  
         [0069]    [0069]FIGS. 6 a  and  6   b  illustrate cross sectional views of yet another modification of the vapor separator cooling system  114 , identified generally by the reference numeral  114 B. Components of the cooling system  114 B that correspond to the respective components of the cooling system  114  have been identified with the same reference numerals, except that a letter “B” has been added thereto.  
         [0070]    In this embodiment, the vapor separator tank is cooled using a thermoelectric element  158 . For example, but without limitation, the thermoelectric element  158  can be Peltier device. Optionally, the thermoelectric element  158  can be disposed in a body  153 B. The thermoelectric element is configured to cool the vapor separator tank  124  by passing a predetermined amount of current (I) through a thermoelectric element that is made up junctions of dissimilar metals. When current is passed through the junctions of dissimilar metals, heat is transferred from one junction to the other. This transfer of heat, called the Peltier effect, cools one junction and transfers the heat from the cooled junction to the other junction.  
         [0071]    Additionally, the body  158 B can include outer surface features configured to enhance the discharge of heat to the environment. For example, the body  158 B can include heat dissipating fins  162  disposed on an outer surface of the body  158 B.  
         [0072]    The detachable heat exchanger  132 B with the incorporated thermoelectric element  158  is attached to the vapor separator tank  124  through at least one bolt  146  (FIG. 6 b ). The detachable heat exchanger  132 B incorporating the thermoelectric element can also be attached to the vapor separator tank  124  by other attachment systems including, but not limited to, screws, rivets, and/or an epoxy.  
         [0073]    In the preferred embodiment of FIG. 6 a  and FIG. 6 b  the current allows the junction closest to the vapor separator tank  124  to be cooled and transfers the heat from the cooled junction to the junction farthest away from the vapor separator tank  124 . The heated junction dissipates the transferred heat from the cooler junction through the heat dissipating fins  162 . Thus, the vapor separator is kept cool and the transferred heat is dissipated through the cooling fins  162 .  
         [0074]    Although the present invention has been described in terms of a certain preferred embodiments, other embodiments apparent to those of ordinary skill in the art also are within the scope of this invention. Thus, various changes and modifications may be made without departing from the spirit and scope of the invention. For instance, not all of the features, aspects and advantages are necessarily required to practice the present invention. Accordingly, the scope of the present invention is intended to be defined only by the claims that follow.