Abstract:
This invention provides a method and apparatus for preheating combustion (intake) air of an internal combustion engine during extreme cold ambient temperatures. A valve arrangement is provided to alter the flow of coolant through a radiator and aftercooler. During conditions where intake air temperature is below a predetermined temperature a fluid control valve causes coolant to first flow through a jacket water portion of the engine and next through the aftercooler where the intake air is preheated.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates generally to an internal combustion engine, and more specifically to a method and apparatus for controlling the temperature of combustion (intake) air to the internal combustion engine.  
         BACKGROUND  
         [0002]    Machines that are powered by internal combustion engines must be capable of operating in a variety of environmental conditions. One such example is operation in extreme temperatures. Additionally, customers and governmental regulations often require the engine to operate at maximum efficiency with minimum pollutant output. Research has shown that most diesel engines operate best when intake air temperature is between 42° C. and 48° C. (108° F. and 118° F.). Diesel engines often have turbochargers to increase performance and efficiency. The process of turbo-charging heats the intake air. The amount of heat produced is dependent upon how fast the engine is operating and the amount that the turbocharger is compressing the intake air. At low idle the temperature increase due to turbo-charging may only be 25° C. (77° F.), while at full load the temperature increase of the intake air may be 125° C. (257° F.) or more. Because of this temperature increase it is typical provide a method to cool the intake air.  
           [0003]    Typical methods of cooling the intake air on a turbo-charged diesel engine are through the use of a separate circuit aftercooler (SCAC) or an air to air aftercooler (ATAC). A SCAC comprises a radiator having two portions (SCAC and jacket water), a SCAC pump, and an aftercooler (air to liquid heat exchanger) located down stream from the turbo-charger. Coolant flows from the SCAC portion of the radiator to the SCAC pump, after the SCAC pump the coolant then flows through the aftercooler to remove heat from the intake air. The heated coolant then flows back to the SCAC portion of the radiator.  
           [0004]    During operation of diesel engines in extreme cold temperatures a different problem may occur. If the intake air temperature is below the 42° C.-48° C. (108° F.-118° F.) range, poor combustion may occur. When this condition occurs it desirable to pre-heat the intake air. It would additionally be beneficial to provide an automatic system for controlling the temperature of the intake air.  
         SUMMARY OF THE INVENTION  
         [0005]    In a first aspect of the present invention a liquid cooled internal combustion engine having a radiator, a jacket water pump, an aftercooler and a fluid control valve. The fluid control valve is moveable between a first position and a second position. In the first position the control valve directs coolant from the jacket water pump to the aftercooler and a jacket water circuit of the engine simultaneously. In the second position the control valve directs coolant to the jacket water circuit first and to the aftercooler second.  
           [0006]    In a second aspect of the present invention is a method for controlling the temperature of intake air in an internal combustion engine. The method for controlling the temperature includes providing intake air to an intake air circuit with an aftercooler. Next the temperature of the intake air is determined, if the temperature of the air is below a predetermined value, coolant is directed first through a jacket water circuit and next to the aftercooler. If the temperature is above the predetermined value, coolant is directed simultaneously through the jacket water circuit and the aftercooler. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a schematic illustration of a cooling system having a jacket water pump and fluid control valve used to direct coolant flow.  
         [0008]    [0008]FIG. 2 is a schematic illustration of a cooling system having a jacket water pump, SCAC pump and a fluid control valve used to direct coolant flow. 
     
    
     DETAILED DESCRIPTION  
       [0009]    The following description is of the best mode presently contemplated for carrying out the invention. This description is not intended to be taken in a limiting sense but is make merely for the purpose of describing the general principals of the invention.  
         [0010]    Referring now to FIG. 1 is shown a schematic representation of a simplified cooling system  10  for an internal combustion engine  12 . The cooling system  10  includes a radiator  14 , a jacket water pump  16 , a fluid control valve  18 , a jacket water circuit  20  and an aftercooler  22 . The aftercooler  22  provides an air-to-liquid heat exchanger  24  positioned within an intake air circuit  26 . The intake air circuit  26  extends from an air filter (not shown) to a plurality of combustion chambers (not shown) of the engine  12 .  
         [0011]    The jacket water pump  16  has a supply line  28  having a first end  30  that connects to an outlet  32  near the bottom of the radiator  16  and a second end  34  that connects an inlet  36  on the jacket water pump  16 . The jacket water pump  16  has an outlet  38  that connects to a first end  39  of a jacket water line  40 . The jacket water line tee&#39;s to provide a second end  42  that connects to a first inlet port  43  on the fluid control valve  18 , and a third end that  40  connects to an inlet  44  on a jacket water portion  46  of the engine  12 . A first outlet port  48  of the fluid control valve  18  connects to a first end  50  of an aftercooler line  52 . A second end  60  of the aftercooler line  52  connects to an aftercooler inlet  62 . The jacket water portion  46  of the engine  12  includes an outlet  64  that is connected by an outlet line  66  to a second inlet port  68  of the fluid control valve  18 . A second outlet port  70  of the fluid control valve  18  is connected to a first end  72  of a jacket water return line  74 . A second end  76  of the jacket water return line  74  connects to a return port  78  on the radiator  14 .  
         [0012]    The fluid control valve  18  contains a spool  80  that is moveable between a first position  82  and a second position  84 . In the first position  82  the spool  80  acts to connect the first inlet port  42  to the first outlet port  48  and connect the second inlet port  68  to the second outlet port  70 . In the second position  82  the spool  80  closes the first inlet  42  and second outlet  70  ports while connecting the second inlet port  68  to the first outlet port  42 . The fluid control valve  18  may be either manually or automatically actuated. An automatic fluid control valve  18  may be connected to an electronic controller  86 . The electronic controller  18  may be connected to a temperature sensor  88  positioned in the intake air circuit  26  downstream of the aftercooler  22 .  
         [0013]    Referring now to FIG. 2 is shown a schematic representation of a simplified cooling system  10 ′ for an internal combustion engine  12  having a SCAC (separate circuit aftercooler) circuit  92 . The cooling system  10 ′ includes a radiator  14 ′, a jacket water pump  16 , a fluid control valve  18 ′, a jacket water circuit  20 , an aftercooler  22  and a SCAC pump  94 . The radiator  14 ′ is similar to that of FIG. 1 but additionally includes a vertical partition  96  to create a jacket water portion  98  and a SCAC portion  100  of the radiator. The partition  96  forms a partial barrier between the jacket water portion  98  and the SCAC portion  100 .  
         [0014]    The jacket water circuit  20 ′ provides fluid communication from the jacket water portion  98  of the radiator to the jacket water pump  16  via a jacket water supply line  28 . A first end  30  of the jacket water supply line  28  connects to the outlet  106  of the jacket water portion  98  of the radiator  14 ′ and a second end  34  of the jacket water supply line  28  connects to the jacket water pump inlet  36 . A first end  41  of a jacket water line  40  connects the outlet  38  of the jacket water pump  16  and a second end  42  attaches to an inlet  44  on the jacket water portion  46  of the engine  12 . An outlet  106  on the jacket water portion  46  of the engine  12  connects to the first end  72  of a jacket water return line  74  and the second end  76  of the jacket water return line  74  connects to the second inlet port  68 ′ of the fluid control valve  18 ′. A second outlet port  70 ′ of the fluid control valve  18  connects to a first end  108  of a second jacket water return line  110 , the second end  112  of the second jacket water return line  110  connects to an inlet  114  on the jacket water portion  98  of the radiator  14 ′.  
         [0015]    The SCAC circuit  92  provides fluid communication from the SCAC portion  100  of the radiator  14 ′ to the inlet  124  of the SCAC pump  94 . An outlet  116  on the SCAC portion  100  of the radiator  14 ′ is connected to a first end  118  of a SCAC supply line  120 . A second end  122  of the SCAC supply line  120  connects to an inlet  124  on the SCAC pump  94 . An outlet  126  on the SCAC pump  94  is connected to a first end  128  of a first SCAC line  130 . A second end  132  of the first SCAC line  130  connects to the first inlet port  43 ′ of the fluid control valve  18 ′. The first outlet port  48 ′ of the fluid control valve  18 ′ connects to a first end  132  of a second SCAC line  136 . A second end  138  of the second SCAC line  136  connects to an inlet  62  on the aftercooler  22 . An outlet  140  of the aftercooler  22  connects to a first end  142  of a first SCAC return line  144 . A second end  146  of the first SCAC return line  144  connects to the third inlet port  102  of the control valve  18 ′. The third outlet port  104  of the fluid control valve  18 ′ connects to a first end  148  of a second SCAC return line  150  and a second end  152  of the second SCAC line  148  connects to the return port  154  of the SCAC portion  100  of the radiator  114 ′.  
         [0016]    The fluid control valve  18 ′ also contains a spool (not shown) that is moveable between a first position  82 ′ and a second position  84 ′. When the spool  80 ′ of the fluid control valve  18 ′ is the first position  82 ′ the each of the first, second and third inlet ports ( 42 ′, 68 ′, 102 ) connect to the each of the respective outlet ports ( 44 ′, 70 ′, 104 ) of the fluid control valve  18 ′. When the spool  80 ′ is in the second position  82 ′ the first inlet port  42 ′ connects to the third outlet port  104 ′, the second inlet port  68 ′ connects to the third inlet port  102 ′, and the first outlet port  48 ′ is connected to the second outlet port  70 ′.  
         [0017]    The fluid control valve  18 ′ may be either manually or automatically actuated. An automatic fluid control valve  18 ′ may be connected to an electronic controller  86 ′. The electronic controller  86 ′ may be connected to a temperature sensor  88 ′ located intake air stream.  
         [0018]    As an alternative to the above described cooling systems, a number of components such as oil coolers, turbocharger coolers, bypasses and expansion tanks may be included in the system. Such components have been removed from the description to focus on the invention.  
         [0019]    Industrial Applicability  
         [0020]    The present invention is a system for controlling the temperature of intake (combustion) air of an internal combustion engine  12 . Primarily the invention is intended to provide an apparatus for preheating the intake air during operation in extremely cold temperatures.  
         [0021]    Referring now to FIG. 1 is illustrated a typical cooling system  10  having a single section radiator  14 , a jacket water pump  16  and a fluid control valve  18 . The cooling system  12  is coupled to an internal combustion engine  10  having a jacket water portion  46  for removing heat from the engine  12  and an aftercooler  22  for controlling the temperature of the intake air prior to combustion. Coolant in the radiator  14  is supplied to the jacket water pump  16  through a jacket water supply line  28  connected to the lower portion of the radiator  14 . The jacket water pump  16  provides a flow of coolant to the jacket water circuit  20  and the first inlet port  43  of the fluid control valve  18 . The first outlet port  48  of the fluid control valve  18  is connected to an aftercooler line  52  that provides flow to the inlet  62  of the aftercooler  22 . The outlet  64  of the aftercooler  22  is connected to a jacket water return line  74  that provides flow back to the radiator  14 . The outlet  64  of the aftercooler  22  is connected to the second inlet port  68  of the fluid control valve  18 . The second outlet  70  of the fluid control valve  18  is connected to the jacket water return line  74 . The jacket water return line  74  may be the same line that connects the outlet  64  of the aftercooler  22  to the radiator  14 . In the first position  82 , the spool of the fluid control valve  18  connects the first inlet port  43  to the first outlet port  48  and the second inlet port  68  to the second outlet port  70 . In the second position  84 , the fluid control valve  18  blocks the first inlet port  43  and the second outlet port  70  while connecting the second inlet port  68  to the first outlet port  48 .  
         [0022]    In operation, when the spool of the fluid control valve  18  is in the first position  82 , flow from the jacket water pump  16  goes simultaneously to the aftercooler  22  and the jacket water circuit  20 . When the spool is in the second position  84 , flow from the jacket water pump  16  is first to the jacket water circuit  20  where heat is removed from the engine. Flow from the jacket water circuit  20  then is directed by the fluid control valve  18  to the inlet of the aftercooler  22 . The coolant that was heated by the jacket water circuit  20  then heats the intake air going to the combustion chambers.  
         [0023]    The fluid control valve  18  may be either manually actuated or an automatically actuated. For an automatically actuated system, a temperature sensor  88  to provides an input signal to an electronic controller  86 . The input signal is dependent on the temperature of the intake air. The electronic controller  86  evaluates the signal to determine if the temperature of the intake air is below a predetermined temperature. If the temperature is above a predetermined temperature the spool in the fluid control valve  18  is moved to the first position  82 , causing flow to go from the jacket water pump  16  through the jacket water circuit  20  and aftercooler  22  simultaneously. If the temperature is below a predetermined value coolant flows from the jacket water pump  16  to the jacket water circuit  20  of the engine  12  then to the aftercooler  22 . Using an infinitely controllable valve  18  allows the system to moderate the intake air temperature more precisely.  
         [0024]    Referring now to FIG. 2, a radiator  14 ′ having a jacket water portion  98  and a SCAC portion  100  supplies coolant to a jacket water pump  16  and a SCAC pump  94 . It should be noted the partition  96  between the jacket water portion  98  and the SCAC portion  100  does not totally isolate the portions  98 - 100 , coolant is permitted to equalize and flow between the systems. Coolant flows from the jacket water pump  16  to the inlet  45  of the jacket water portion  46  of the engine  12  through the jacket water line  40 . From the outlet  109  of the jacket water portion  46  the jacket water return line  74  carries coolant to the second inlet port  68 ′ of the fluid control valve  18 ′. With the spool of the fluid control valve  18 ′ in the first position  82  coolant continues through to the second outlet port  70 ′ and returns to the jacket water portion  98  of the radiator  14 ′.  
         [0025]    Coolant from the SCAC pump  94  flows to the first inlet port  43 ′ of the fluid control valve  18 ′. When the spool of the fluid control valve  18 ′ is in the first position  82  coolant flows from the first inlet port  43 ′ to the first outlet port  48 ′. From the first outlet port  48 ′ coolant flows through the aftercooler  22  removing excess heat from the intake air. From the aftercooler  22  outlet  64  the now heated coolant flows to the third inlet port  102  of the fluid control valve  18 ′. Still in the first position, the fluid control valve  18 ′ causes coolant to return to the SCAC portion  100  of the radiator  14 ′.  
         [0026]    Moving the spool of the fluid control valve  18 ′ to the second position  82  causes flow from the SCAC pump  94  to bypass the aftercooler  22  and circulate directly back to the SCAC portion  100  of the radiator  14 ′. Coolant from the jacket water pump  16  flows through the jacket water portion  46  of the engine  12  to the first inlet port  43 ′ of the fluid control valve  18 ′. The fluid control valve  18 ′ now causes the heated coolant to flow out of the third inlet port  102  of the fluid control valve  18 ′ and through the aftercooler  22 , heating the intake air. After flowing through the aftercooler  22  the coolant enters the first outlet port  48 ′ of the fluid control valve  18 ′, on to the second outlet port  70 ′, and back to the jacket water portion  98  of the radiator  14 ′.  
         [0027]    Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.