Abstract:
A cooling system for a turbo-charged internal combustion engine utilizing a unified flow control valve capable of changing the mode of operation of the system in response to a varying heat demand. The unified flow control valve may be a solenoid operated slider valve having a cylinder with connections to the engine water jacket outlet, the intercooler inlet, the radiator inlet and outlet, and the water tank, and a piston having rows of openings which when aligned with the cylinder connections provide flow paths corresponding to various modes of operation.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a cooling system for high-power internal combustion engines and, more particularly, to a cooling system for a diesel engine powered locomotive traction vehicle. 
     Cooling systems for internal combustion engines, such as the diesel engines used in locomotives, are known in the art for the purpose of maintaining engine and lubricating oil temperatures within desired operating ranges. Turbo-charged engines are also known to utilize cooling systems for conditioning the combustion inlet air after it is compressed in a turbo-charger. U.S. Pat. No. 5,415,147, incorporated by reference herein, describes a temperature regulating system for a turbocharged locomotive engine that is specifically designed to address the need for different cooling modes dependent upon changes in ambient air temperature and engine load. In one flow path taught in that patent, coolant heated by the engine is cooled by a primary radiator having a split outflow such that a portion may be further cooled in a subcooler. The coolant portion flowing through the subcooler is directed either to an engine intake air intercooler or back to a water reservoir. In a second flow path, heated coolant from the engine may be directed to the intercooler to heat the engine intake air. 
     The temperature regulating system of U.S. Pat. No. 5,145,147 defines three modes of operation as follows: 
     Mode 1: The entire hot coolant outflow from the engine is directed to the radiator/subcooler. Coolant passing through the subcoolers is used to cool the engine intake air in the intercooler. Mode 1 is used when coolant temperatures are highest, such as when the engine is at the highest power levels and/or when the highest ambient air temperatures are encountered. 
     Mode 2: The radiator/subcooler are used to cool only a portion of the hot coolant outflow from the engine. The remainder is used to heat the engine intake air in the intercooler. Mode 2 is used when coolant temperature is high enough to warrant cooling but heating of the intake air is desired to obtain optimal engine operation. 
     Mode 3: None of the coolant outflow from the engine is cooled in the radiator, but some of this heated coolant is used to heat the engine intake air in the intercooler. The radiator and subcooler are drained in this mode. Mode 3 is utilized when the heat demand on the engine is lowest, such as at low power loads and/or cold ambient air temperatures. 
     The particular flow paths for each of the three modes described above are disclosed in U.S. Pat. No. 5,415,147 along with the flow control system valving required to implement this cooling flow control system. The flow control system includes a two-position three-way “T-port” rotary valve shafted to an external air powered actuator (item 112 of the patent) and an associated on-off butterfly valve (item 206) for drainage of radiator inlet piping, and a second two-position three-way “L-port” valve shafted to an external air powered actuator (item 144) and its associated second on-off butterfly valve (item 168) for drainage of the subcooler outlet piping. Table 1 below illustrates the possible combinations of valve positions for the three way valves, with the flow ports of the valves designated as A, B and C. Three of the four combinations are used for implementing modes 1, 2, and 3 described above, and the fourth combination is unused in the prior art embodiments. 
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Cooling System Mode vs Valve Position 
               
             
          
           
               
                   
                 T 
                 T 
                 L 
                 L 
                   
               
               
                 Mode 
                 3-way 
                 2-way 
                 3-way 
                 2-way 
                 Flow Path 
               
               
                   
               
               
                 3 
                 C to B 
                 Open 
                 C to B 
                 Open 
                 Eng to W/T &amp; I/C Rad &amp; 
               
               
                   
                   
                   
                   
                   
                 S/C to W/T 
               
               
                 2 
                 C to A 
                 Closed 
                 C to B 
                 Open 
                 Eng to Rad &amp; I/C, S/C 
               
               
                   
                   
                   
                   
                   
                 to W/T 
               
               
                 1 
                 C to A 
                 Closed 
                 A to B 
                 Closed 
                 Eng to Rad, S/C to I/C 
               
               
                 X 
                 C to B 
                 Open 
                 A to B 
                 Closed 
                 Not Used 
               
               
                   
               
             
          
         
       
     
     The following abbreviations are used in Table 1: Eng for engine; W/T for water tank; I/C for intercooler; Rad for radiator; and S/C for subcooler. 
     Note that the fourth mode, indicated by Mode “X” in Table 1, is not used in the system described in U.S. Pat. No. 5,415,147, but is nonetheless available and may become “operational” due to a failure(s) in the valves. 
     The prior art system provides several operational advantages. However, it contains many valves and piping connections, thereby increasing the cost of manufacturing, the cost of operation, and the overall reliability of the system. Accordingly, it is an object of this invention to provide a cooling system for a turbo-charged internal combustion engine that provides all of the operational flexibility of the prior art system of U.S. Pat. No. 5,415,147 while being simpler and less expensive to construct and to operate. It is a further object of this invention to provide a cooling system and that is more reliable in its operation than prior art systems. 
     SUMMARY OF THE INVENTION 
     Accordingly, a cooling system for a turbo-charged internal combustion engine is disclosed having: a water tank operable to contain cooling water and having an inlet and an outlet; a pump operable to circulate water throughout the cooling system and having a inlet connected to the water tank outlet and an outlet; an engine water jacket associated with the engine and having an inlet connected to the pump outlet and an outlet; a combustion air intercooler having an outlet connected to the water tank inlet and an inlet; a radiator having an inlet and an outlet; and a flow control valve having connections to the water jacket outlet, the intercooler inlet, the radiator inlet, the radiator outlet, and the water tank inlet. More particularly, the flow control valve defines three flow paths for the cooling water: a first flow path connecting the water jacket outlet to the radiator inlet, and connecting the radiator outlet to the intercooler inlet; a second flow path connecting the water jacket outlet to the radiator inlet and the intercooler inlet, and connecting the radiator outlet to the water tank inlet; and a third flow path connecting the water jacket outlet to the intercooler inlet and the water tank inlet, and connecting the radiator inlet and outlet to the water tank inlet. The flow control valve may further have a cylinder having openings connected to the water jacket outlet, the intercooler inlet, the radiator inlet, the radiator outlet, and the water tank inlet; a piston disposed within the cylinder and having a plurality of openings formed therein, the piston operable to be moved to three positions within the cylinder, each position corresponding to one of the three flow paths. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts the heat regulating system disclosed in the prior art, as it would operate in Mode 1; 
     FIG. 2 depicts the heat regulating system disclosed in the prior art, as it would operate in Mode 2; 
     FIG. 3 depicts the heat regulating system disclosed in the prior art, as it would operate in Mode 3; 
     FIG. 4 depicts a schematic of a cooling system in accordance with the present invention utilizing a unified control valve for Mode 1 operation; 
     FIG. 5 illustrates the flow path through the integrated control valve of FIG. 4 as it would be configured for Mode 2 operation; 
     FIG. 6 illustrates the flow path through the integrated control valve of FIG. 4 as it would be configured for Mode 3 operation; 
     FIG. 7 depicts a top view of an integrated flow control valve in accordance with the present invention; 
     FIG. 8 depicts an end view of the integrated flow control valve of FIG. 7; and 
     FIG. 9 depicts a side view of the integrated flow control valve of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to understand the improvements offered by the present invention, it is useful to analyze the heat regulating systems as disclosed in prior art U.S. Pat. No. 5,415,147. FIGS. 1-3 illustrate the flow paths of the three operational modes of a heat regulating system as disclosed in that patent, with like structures being numbered consistently among all of the Figures in this application. Note that there are no structural differences between the systems in FIGS. 1-3. Rather, the differences are related solely to the positions of the valves in the system. 
     FIG. 1 illustrates mode 1 operation of a prior art system  10  in which cooling water is drawn by pump  12  through oil cooler  14  from a water tank  16 . The cooling water is directed to the water jacket  18  of an internal combustion engine where heat is transferred from the engine to the cooling water. Hot coolant outflow from the engine water jacket  18  flows through three-way “T-port” valve  20  to radiator  22 . A portion of the flow exiting the radiator  22  flows directly to the water tank  16 , while a second portion is further cooled in subcooler  24  and is then directed through three way “L-port” valve  26  to inlet air intercooler  28  before being directed back to the water tank  16 . Fan  30  provides cooling air to the radiator  22  and subcooler  24 , and orifices  32 , 34  provide the desired flow balance between the alternative coolant flow paths. Note the positions of the three way valve assemblies  20 , 26 . In Mode 1, the three-way “T-Port” valve  20  is positioned to pass flow from C to A, as indicated by a black valve body on the figure, and the associated two-way butterfly valve  36  is closed, as indicated by a white valve body on the figure. The three-way “L-Port” valve  26  is positioned A to B, and its associated butterfly valve  38  is closed. In Mode 1, all of the coolant exiting the engine water jacket  18  must flow to the C Port of valve  20  where it then exits through Port A. The coolant then passes through the radiator  22 . The outflow from the radiator  22  is split, with a portion of the coolant going directly to the water tank  16  through orifice  34 , and the remainder going to subcooler  24  for further cooling by fan  30 . The coolant traveling through the subcoolers  24  is directed to Port A of valve  26 . Upon exiting valve  26  through Port B, the coolant then flows to the intercooler  28 , where the coolant is used to cool the engine intake air. This portion of the coolant then returns to the water tank  16 . 
     FIG. 2 illustrates the prior art cooling system of FIG. 1 with valves  20 , 26 , 36 , 38  in position for mode 2 operation. Valve  20  is positioned C to A, and its associated butterfly valve  36  is closed, as in Mode 1. Valve  26 , however, is positioned C to B, allowing a portion of the heated coolant exiting the engine water jacket  18  to flow to intercooler  28  to heat the incoming combustion air. This position of valve  26  also prevents cooled water from the subcooler  24  outlet from entering intercooler  28 . Butterfly valve  38  is open in order to direct the portion of the coolant that has been cooled in radiator  22  and subcooler  24  to water tank  16 . 
     Referring now to FIG. 3, Mode 3 which is for the coldest operating conditions, requires the radiator  22  and subcooler  24  to be completely bypassed and drained to water tank  16 . Valve  26  directs a portion of the heated coolant exiting the water jacket  18  to intercooler  28 , with the remainder of the flow being directed to the water tank  16  by valve  20 . Valves  36 , 38  are opened to allow the radiator  22  and subcooler  24  to drain, preferably by the force of gravity alone, to water tank  16 . 
     FIG. 4 illustrates a schematic of a cooling system  40  built in accordance with the present invention. FIG. 4 illustrates the cooling system  40  aligned to operate in mode 1 as discussed above. The cooling system  40  is similar in function to cooling system  10  shown in FIGS. 1-3, but importantly valves  20 , 26 , 36 , 38  and much of the associated piping of the prior art have been replaced by an integrated flow control valve  50 . Modes 1-3 can be achieved by operating flow control valve  50  to change the interconnections among the various system components as illustrated in FIGS. 4-6 respectively. 
     Referring to FIG. 4, flow control valve  50  has connections to the outlet  52  of engine water jacket  18 , to the inlet  54  of intercooler  28 , to the inlet  56  of radiator  22 , to the outlet  58  of subcooler  24 , and to the inlet  60  of water tank  16 . Water tank  16  has an outlet that is in fluid communication with water jacket  18 , in this embodiment through oil cooler  14  and pump  12 . Also note that outlet  62  of radiator  22  is connected to flow control valve  50  through the subcooler  24 , although in some embodiments it may be connected directly if no subcooler is provided. Flow control valve  50  is illustrated in FIG. 4 in a first position where the water jacket outlet  52  is connected to radiator inlet  56 , and radiator outlet  62  (and subcooler outlet  58 ) is connected to intercooler inlet  54 . In this position the water tank inlet connection  60  is isolated. Thus, the system  40  of FIG. 4 functions the same as system  10  of FIG. 1 but with a significantly reduced number of active components and piping connections. 
     FIG. 5 is a schematic diagram of the integrated flow control valve  50  of FIG. 4 but configured in a second position in order to provide for mode 2 operation of coolant system  40 . In FIG. 5, flow control valve  50  provides a second flow path for system  50  which connects water jacket outlet  52  to both the radiator inlet  56  and the intercooler inlet  54 , and connects the radiator outlet  62  (or subcooler outlet  58 ) to the water tank inlet  60 . Thus, the system  40  of FIG. 4, with flow control valve configured as shown in FIG. 5, functions the same as system  10  of FIG. 2 but with a significantly reduced number of active components and piping connections. 
     FIG. 6 is a schematic diagram of the integrated flow control valve  50  of FIG. 4 configured in a third position in order to provide for mode 3 operation of coolant system  40 . In FIG. 6, flow control valve  50  provides a third flow path for system  40  that connects water jacket outlet  52  to both the intercooler inlet  54  and the water tank inlet  60  in order to provide heat to the incoming combustion air. The flow control valve  50  also connects both the radiator inlet  56  and radiator outlet  62  (or subcooler outlet  58 ) to water tank inlet  60  to provide for draining of the radiator  22  and subcooler  24 . Thus, the system  40  of FIG. 4, with flow control valve configured as shown in FIG. 6, functions the same as system  10  of FIG. 3 but with a significantly reduced number of active components and piping connections. 
     FIGS. 7-9 illustrate various views of an embodiment of the flow control valve  50  of the present invention. Like structures are numbered consistently in the various views, and the Figures may best be viewed together in conjunction with the following description. The illustrated embodiment of flow control valve  50  is a “slider” valve design containing an outer cylinder  62  and a linearly movable piston  64 . The piston  64  contains three alternative sets of openings  66 , 68 , 70 . Each of these sets of openings  66 , 68 , 70  may alternately be aligned with the single set of openings in the wall of the cylinder  62  by a sliding motion of the piston  64 . Alignment of openings  66 , 68 , or  70  with the openings in the wall of cylinder  62  will complete the flow path necessary to achieve the desired mode 1, 2 or 3 respectively. The openings in the wall of the cylinder  62  are connected in flow communication with the water jacket outlet  52 , intercooler inlet  54 , radiator inlet  56  and outlet  62 , and water tank inlet  60 . By allowing only three possible modes of operation, the present invention eliminates the failure mode inherent in mode X of the prior art as illustrated in Table 1 above. 
     A single actuator, such as three-position pneumatic actuator  72  is provided to slide piston  64  to the positions necessary to achieve the desired flow path for the various modes. For example, if the actuator  72  is fully inserted into the cylinder  62 , piston  64  will be in a first position aligning the openings  66  in the piston  64  with openings in the cylinder  62  corresponding to connections  52 , 54 , 56 , 58 / 62 . In this first position flow control valve  50  will function to provide the mode 1 flow path illustrated in FIG.  4 . Similarly, if the actuator  72  is operated to move piston  64  to a position closest to the actuator  72 , the flow openings  70  will be aligned with connections  52 , 54 , 56 , 58 / 62 , 60  to form the flow path shown in FIG. 6 for mode 3. An intermediate actuator position will align the openings  68  with the same connections but in a different alignment to form the flow path shown in FIG. 5 for Mode 2. 
     To ensure the proper alignment of the openings  66 , 68 , 70  in the piston with the openings in the cylinder, the piston  64  must be prevented from rotating about its central axis. Thus, an anti-rotation pin  74  is provided in the cylinder  62  to interface with a groove  76  formed in the piston  64 . Alternatively, actuator  72  may be provided with an anti-rotation feature, provided the piston  64  is prevented from rotating in relation to the actuator  72 . Alternatively, the anti-rotation feature may be provided in the adapter  78  between the cylinder  62  and the actuator  72 . Adapter  78  may also be provided with a vent  79  to ensure that the compressed air utilized to power the actuator  72  does not enter the cooling system  40  by leaking into flow control valve  50 . 
     The flow control valve  50  may be constructed of standard materials known in the art for valves, such as steel or aluminum. The openings may be cast or machined. The piston  64  and cylinder  62  may be designed and manufactured to have a close tolerance therebetween in order to eliminate the need for any sealing mechanism between adjacent openings  66 , 68 , 70  and at the ends of the piston. Alternatively, elastomeric o-ring or band-type seals  80  may be used at one or more locations. Other sealing techniques are known in the art, such as those disclosed in U.S. Pat. No. 4,548,385. The seals  80  are retained in position by separate seal discs  82  at each end of the cylinder. Alternatively, the seal grooves may be formed to be integral with the piston to make a one-piece piston design. 
     A breather passage  84  is required to allow the piston  64  to move back and forth without encountering resistance due to entrapped air. Additionally, a drain connection  86  is provided so that leakage around the piston  64  or seals  80  may be drained to the water tank  16 . The separate breather passage  84  may be combined with the drain connection  86 , thereby eliminating the need to align the seal discs  82  (if used) in order to keep the breather passage  84  in alignment. 
     Other embodiments of integral flow control valve  50  may include a spool design, where the same openings in the piston are brought into alignment with three different sets of ports within the cylinder, or a rotary design, where flow paths are defined by a rotor and port arrangement. 
     As may be appreciated from the Figures, the cooling system of the present invention provides for a reduced number of valves and for the elimination of a significant amount of the flow control piping of the prior art system. It thereby eliminates approximately one-half of the failure modes of the prior art, including parts such as shaft couplings and bolted connections. The design and installation of a system according to the present invention requires less time and less space, and for mobile applications such as a locomotive cooling system, the weight reduction compared to the prior art will provide a corresponding savings in fuel consumption. Furthermore, because the number of valves to be controlled is reduced, the coolant flow control system of the present invention is more reliable and less costly than prior art systems.