Abstract:
An intercooler system and method of operation for use with an air charging system for an internal combustion engine is disclosed. The intercooler system may comprise an intercooler pump for pumping a coolant through the intercooler system, a first heat exchanger that transfers heat from charged intake air to the coolant, a second heat exchanger that transfers heat from the coolant to outside air, and an intercooler coolant reservoir that contains the coolant therein. Coolant lines direct a flow of the coolant through the intercooler pump, the first heat exchanger, the second heat exchanger and the intercooler coolant reservoir.

Description:
BACKGROUND OF INVENTION 
       [0001]    The present invention relates generally to intake air charging for an internal combustion engine, and more particularly to an intercooler circuit for the intake air charging system. 
         [0002]    Some vehicles include intake air charging systems, such as superchargers or turbo chargers, in order to increase the air intake charge in the cylinders and thus boost the engine output. During an acceleration burst, the intake charge boost compresses the intake charge significantly, which raises its temperature dramatically. On some vehicles, an intercooler system is used to reduce the intake charge temperature in order to provide an even more dense intake air charge, thus maximize engine power. In such systems, the effectiveness of the intercooler directly affects the engine power output. 
         [0003]    A desire exists, then, to improve the effectiveness of the intercooler. When an air-to-liquid intercooler heat exchanger (ICHE) is employed, the size of the ICHE may be increased to improve the effectiveness of the intercooler. Increasing the size of the ICHE, however, may restrict the air flow to a condenser, radiator, fan module (CRFM), which will adversely effect other vehicle cooling systems. Others have suggested employing a refrigerant system to improve intercooler effectiveness. However, this may be too costly and complex of a solution for particular vehicle applications. 
       SUMMARY OF INVENTION 
       [0004]    An embodiment contemplates an intercooler system for use with an air charging system for an internal combustion engine. The intercooler system may comprise an intercooler pump for pumping a coolant through the intercooler system, a first heat exchanger configured to transfer heat from charged intake air to the coolant, a second heat exchanger configured to transfer heat from the coolant to outside air, and an intercooler coolant reservoir configured to contain the coolant therein. Coolant lines direct a flow of the coolant through the intercooler pump, the first heat exchanger, the second heat exchanger and the intercooler coolant reservoir. 
         [0005]    An embodiment contemplates a method of cooling charged intake air entering an internal combustion engine, the method comprising the steps of: transferring heat from the charged intake air to a coolant flowing through a first heat exchanger; transferring heat from the coolant flowing through a second heat exchanger to surrounding air; pumping the coolant through an intercooler pump; and receiving, storing and discharging the coolant from an intercooler coolant reservoir. 
         [0006]    An advantage of an embodiment is that the performance of a supercharged (or turbo charged) engine is improved by improving the intercooler system performance during periods of sustained air intake boost. The intercooler system performance is improved by providing an intercooler coolant reservoir, which adds additional short-term thermal capacity, and hence thermal inertia, to the intercooler system. As the intake charge typically only requires cooling under periods of sustained supercharger boost, the bulk temperature of the intercooler coolant is usually quite cool. Under periods of high boost, the additional coolant volume, which is stored in the reservoir, slows the rate of climb of the charge air temperature, reducing peak charge temperatures and allowing for a cooler, more dense intake charge and therefore higher available power levels. Moreover, the improved intercooler system performance is accomplished without increasing the size of the intercooler heat exchanger (ICHE) itself, which can degrade the cooling efficiency of condenser, radiator, fan module (CRFM) components due to additional airflow restrictions to the CRFM opening that would be caused by a larger ICHE. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  is a schematic diagram illustrating a portion of a vehicle, including an intercooler system. 
           [0008]      FIG. 2  is a schematic diagram showing a portion of the intercooler system. 
           [0009]      FIG. 3  is a view similar to  FIG. 2 , but illustrating a second embodiment. 
           [0010]      FIG. 4  is a view similar to  FIG. 2 , but illustrating a third embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring to  FIGS. 1 and 2 , a portion of a vehicle, indicated generally at  20 , is shown. The vehicle  20  includes an internal combustion engine  22  having an intake manifold  24  that directs air into engine cylinders (not shown). An intake air charger  26 , such as a supercharger or turbo charger, compresses an air charge and directs the compressed air charge into the intake manifold  24 . In order to improve the performance of the intake air charger  26 , an intercooler system  28  is employed. 
         [0012]    The intercooler system  28  includes a pair of intercooler bricks (heat exchangers)  30  in the intake manifold  24 , a pump-to-manifold coolant line  32  directing a coolant from an intercooler pump  34  to the intercooler bricks  30 , a manifold-to-heat exchanger coolant line  36  directing the coolant from the bricks  30  to an upper portion  42  of an intercooler heat exchanger (ICHE)  38 , and a heat exchanger-to-pump coolant line  40  directing the coolant from a lower portion  44  of the ICHE  38  to the intercooler pump  34 . The coolant may be any type of liquid used for heat transfer, such as, for example a mixture of ethylene glycol and water. The coolant in the intercooler system  28  is separate from the engine cooling system, so coolant from the two systems does not intermix. The intercooler bricks  30  are liquid-to-air heat exchangers that extract heat from the charged intake air prior to the air entering the cylinders. The intercooler pump  34  is an electric pump that pumps coolant from the ICHE  38  to the intercooler bricks  30 . The ICHE  38  is a liquid-to-air heat exchanger where heat is absorbed by air flowing through the ICHE  38 . 
         [0013]    The intercooler system  28  also includes an intercooler coolant reservoir  46 . The reservoir  46  may be sized to hold, for example, about 1-4 liters of coolant, depending upon the particular vehicle intercooler system. Of course, the reservoir  46  may be sized to hold more or less coolant, if so desired. The reservoir  46  receives coolant from the upper portion  42  of the ICHE  38  via a heat exchanger-to-reservoir coolant line  48  and directs coolant, via a reservoir-to-heat exchanger coolant line  50 , to the lower portion  44  of the ICHE  38 . The reservoir  46  may include a fill cap  52  for adding coolant to the intercooler system  28 . While the ICHE  38  may be mounted in front of an opening to a condenser, radiator, fan module (CRFM)  54 , preferably the reservoir  46  is not in front of this opening so that it does not interfere with air flow into the CRFM  54 . 
         [0014]    Operation of the intercooler system  28  includes activating the intercooler pump  34 , which pumps the coolant through the system. The coolant is pumped through the intercooler bricks  30 , where the coolant absorbs heat from the charged intake air. The cooled intake air entering the cylinders is now more dense, allowing for more engine power output. The coolant, after absorbing heat from the charged intake air, then flows to the ICHE  38 . The direction of coolant flow through the ICHE  38  and the reservoir  46  is indicated by the arrows in  FIG. 2  (and  FIGS. 3-4 , discussed below). As the coolant flows through the upper portion  42  of the ICHE  42 , air flows through the ICHE  42 , absorbing heat from the coolant. The coolant then flows through the reservoir  46  and back to a lower portion  44  of the ICHE  42 . Again, air absorbs heat from the coolant. The coolant then flows to the pump  34  to complete the circuit. 
         [0015]    For a typical supercharged vehicle, the intake charge may only require cooling under periods of sustained supercharger boost. Thus, the bulk temperature of the coolant is typically relatively cool. The intercooler coolant reservoir  46  provides a larger overall coolant volume and thus a greater thermal mass at this relatively cool temperature. Consequently, the reservoir  46  adds short-term thermal capacity (and thus thermal inertia) to the intercooler system  28 , slowing the rate of climb of the coolant temperature. This allows for a reduction in peak temperatures for the charged intake air during wide open throttle operation, which typically only occurs for short periods of time. Reducing the peak temperature for the charged intake air allows for a more dense air/fuel charge in the cylinders, resulting in more vehicle power. The reduced peak temperature may also allow for a more aggressive spark advance, which may lead to greater power output. The short term increase in cooling capacity of the intercooler system  28  is accomplished without the need to increase the size of the ICHE  38 . This avoids increasing the air flow restriction for air flowing into the CRFM  54 , which may help to maintain better air flow through a radiator and condenser. 
         [0016]      FIG. 3  illustrates a second embodiment. Since this embodiment is similar to the first, similar element numbers will be used for similar elements, but employing 100-series numbers. In this embodiment, an intercooler coolant reservoir  146  is located upstream of an ICHE  138  rather than at a location that is mid-flow through the ICHE  138 . The coolant flows in this intercooler system  128  through a manifold-to-reservoir coolant line  136 , through the reservoir  146 , and through a reservoir-to-heat exchanger coolant line  148  into an upper portion  142  of the ICHE  138 . The coolant then flows through the upper portion  142 , through the lower portion  144  and out through a heat exchanger-to-pump coolant line  140  to an intercooler pump (not shown in this embodiment). Preferably, the reservoir  146  is located so that it does not inhibit air flow into a condenser, radiator, fan module (not shown in this embodiment). 
         [0017]      FIG. 4  illustrates a third embodiment. Since this embodiment is similar to the first, similar element numbers will be used for similar elements, but employing  200 -series numbers. In this embodiment, an intercooler coolant reservoir  246  is located downstream of an ICHE  238  rather than at a location that is mid-flow through the ICHE  238 . The coolant flows in this intercooler system  228  through a manifold-to-heat exchanger coolant line  236  into an upper portion  242  of the ICHE  238 . The coolant then flows through the upper portion  242 , through the lower portion  244  and out through a heat exchanger-to-reservoir coolant line  250  to the reservoir  246 . From the reservoir  246 , the coolant flows through a reservoir-to-pump coolant line  248  to an intercooler pump (not shown in this embodiment). The reservoir  246  can be packaged wherever there is sufficient space and room to route the coolant lines. Preferably, the reservoir  246  is located low enough vertically to allow for good coolant fill and de-aeration of the coolant, which is preferable for the first two embodiments as well. 
         [0018]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.