Abstract:
A method for operating a fuel system for an internal combustion engine during engine start, is disclosed. The fuel system includes a fuel supply system in fluid communication with a fuel delivery system and a cooling circuit. The cooling circuit is configured to transfer heat from the fuel delivery system. The method includes provision of fuel to the fuel delivery system and isolation of the fuel from the cooling circuit. Thereafter, a pressure between the fuel supply system and the fuel delivery system is sensed. Determination is carried out when the pressure is greater than a predetermined threshold fuel pressure. Subsequently, based on the determined pressure, fuel to the cooling circuit is provided.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure generally relates to a fuel system for an internal combustion engine of a machine. More specifically the present disclosure relates to the fuel system with a priority valve in the internal combustion engine of the machine. 
       BACKGROUND 
       [0002]    An internal combustion engine is well known in the art as a power source for various machines. A crank of the internal combustion engine may be rotated to start the internal combustion engine. Crank rotation may be performed by an electric motor or by manual intervention. The process of rotating the crank by the above stated means may be termed as cranking The time required to start the internal combustion engine may be termed as cranking time. A fuel is supplied to the internal combustion engine during cranking to start the combustion. The fuel may be supplied by a fuel system. Fuel systems generally include fuel injectors, fuel pumps, common rails, and the like. 
         [0003]    Such fuel systems may require to be cooled during the operation of the internal combustion engine by use of a cooling fluid. The cooling fluid may include engine coolant or fuel. When fuel is used as a coolant, a portion of the fuel supplied by a fuel pump is diverted to a related cooling circuit. However, during engine cranking, the diversion of fuel may increase the time duration for a threshold pressure build-up. As the time taken to achieve the threshold fuel pressure increases, the internal combustion engine takes more time to start the operation. 
         [0004]    Various solutions have been developed to address the challenges cited above. The present disclosure is directed towards overcoming the above-stated challenges. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    The present disclosure provides a method for operating a fuel system for an internal combustion engine during an engine start. The fuel system includes a fuel supply system in fluid communication with a fuel delivery system and a cooling circuit. The cooling circuit is configured to transfer heat from the fuel delivery system. The method includes a provision of fuel to the fuel delivery system and an isolation of the fuel from the cooling circuit. Next, detection of a pressure between the fuel supply system and the fuel delivery system is carried out. Thereafter, by determining that the pressure is greater than a predetermined threshold fuel pressure, fuel is provided to the cooling circuit. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0006]      FIG. 1  illustrates a schematic block diagram of a fuel system for an internal combustion engine, in accordance with the concepts of the present disclosure; 
           [0007]      FIG. 2  illustrates a schematic block diagram of the fuel system for the internal combustion engine in an alternate embodiment, in accordance with the concepts of the present disclosure; 
           [0008]      FIG. 3  illustrates a schematic block diagram of the fuel system for the internal combustion engine in an alternative embodiment, in accordance with the concepts of the present disclosure; and 
           [0009]      FIG. 4  illustrates a flow chart, which describes a method of operating the fuel system for the internal combustion engine, in accordance with the concepts of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]      FIG. 1  illustrates a block diagram of a fuel system  100  for an internal combustion engine  102 , in accordance with the concepts of the present disclosure. In reference to  FIG. 1 , the fuel system  100  may include a fuel supply system  104 , a fuel delivery system  106 , a cooling circuit  108 , a priority valve  110 , a sensor  112  and a controller  114 . 
         [0011]    The fuel supply system  104  may further comprise a fuel tank  116  and a fuel pump  118 . The fuel tank  116  is configured to store the fuel. The fuel stored may be a liquid fuel such as petrol, diesel, a gaseous fuel, liquefied natural gas, hydrogen, and/or the like. Further, the fuel pump  118  supplies the fuel from the fuel tank  116  to the fuel delivery system  106  and the cooling circuit  108 . The fuel supply system  104  stores and supplies fuel for operations of the internal combustion engine  102 . 
         [0012]    In an embodiment, the fuel may flow through a fuel filter (not shown), which may be located either upstream or downstream of the fuel pump  118 . The fuel filter (not shown) may be configured to screen impurities, such as dirt, rust, debris, and/or the like, from the fuel. The fuel filter (not shown) may be a plastic filter, a paper filter, coil-type filter, and/or the like. Other filter types may be contemplated, as apparent to those of skill in the art. When positioned downstream of the fuel pump  118 , the fuel filter (not shown) may provide relatively clean fuel to the fuel delivery system  106  and the cooling circuit  108 . 
         [0013]    The fuel delivery system  106  is configured to inject fuel into a combustion chamber of the internal combustion engine  102  at relatively high pressure. The fuel delivery system  106  may include various components, such as, but not limited to, a high-pressure pump, a common rail, a high-pressure line, and one or more fuel injectors. The high-pressure pump may facilitate fuel supply to the fuel injector, via the high-pressure line. The injection of the fuel at high pressure may atomize the fuel within the combustion chamber of the internal combustion engine  102 . Atomization of the fuel by the fuel injector may result in improved power output, improved efficiency, and reduced maintenance of the internal combustion engine  102 . 
         [0014]    The cooling circuit  108  is configured to transfer heat away from the fuel delivery system  106 , thereby cooling the fuel delivery system  106 . The cooling circuit  108  may cool one or more of the common rail, the high-pressure line, and/or the fuel injector of the fuel delivery system  106 . In an embodiment, the cooling circuit  108  allows the fuel to flow around the high-pressure line of the fuel delivery system  106 . The fuel flow around the high-pressure line dissipates the heat from the high-pressure line, which results in cooling of the fuel inside the high-pressure line. 
         [0015]    The priority valve  110  is positioned between the fuel supply system  104  and the cooling circuit  108 . The priority valve  110  selectively allows the fuel flow from the fuel supply system  104  to the cooling circuit  108 , when a pressure between the fuel supply system  104  and the fuel delivery system  106  is greater than a threshold fuel pressure. 
         [0016]    In an exemplary embodiment, the priority valve  110  is a three-way valve. The priority valve  110  includes a first port  120 , a second port  122 , and a third port  124 . The first port  120  is in fluid communication with the fuel supply system  104 . The first port  120  receives fuel from the fuel supply system  104 . The second port  122  is in fluid communication with the cooling circuit  108 . This implies that the second port  122  directs the fuel to the cooling circuit  108  from the fuel supply system  104 . The third port  124  is in fluid communication with the fuel delivery system  106  and directs the fuel to the fuel delivery system  106 . 
         [0017]    The sensor  112  may be operably coupled to the priority valve  110 . The sensor  112  may be configured to detect the pressure between the first port  120  and the third port  124  of the priority valve  110 . The sensor  112  may monitor the pressure between the fuel supply system  104  and the fuel delivery system  106 . 
         [0018]    The controller  114  may be configured to regulate the flow between the first port  120  and one or more of the second port  122  and the third port  124 . The controller  114  may regulate the fuel flow from the first port  120  to the second port  122 , based on the pressure detected by the sensor  112 . The controller  114  allows the fuel flow from the first port  120  to the third port  124  throughout an operation of the internal combustion engine  102 . 
         [0019]    During the cranking of the internal combustion engine  102 , the controller  114  may close the second port  122  and may restrict the fuel flow through the second port  122 . As the second port  122  is closed, the fuel pumped by the fuel pump  118  is substantially directed to the third port  124  and to the fuel delivery system  106 . The controller  114  may open the second port  122  once the threshold fuel pressure is detected between the first port  120  and the third port  124 . Thereby, the fuel flow from the fuel supply system  104  is delivered to both the cooling circuit  108  and the fuel delivery system  106  simultaneously. 
         [0020]      FIG. 2  illustrates a schematic block diagram of the fuel system  100  for the internal combustion engine  102  in an alternate embodiment. In this embodiment, the priority valve  110  includes an ON-OFF valve  126 . The ON-OFF valve  126  may be a 2-port 2 position-direction control valve. The ON-OFF valve  126  is positioned in such a way that the ON-OFF valve  126  is in fluid communication with the fuel supply system  104  and the cooling circuit  108 . The priority valve  110  restricts the fuel flow from the fuel supply system  104  to the cooling circuit  108  when the ON-OFF valve  126  is in an OFF position. The priority valve  110  allows the fuel flow from the fuel supply system  104  to the cooling circuit  108  when the ON-OFF valve  126  is in an ON position. The controller  114  controls the related positions of the ON-OFF valve  126 . Moreover, the controller  114  switches the ON-OFF valve  126  in ON position when the pressure between the fuel supply system  104  and the fuel delivery system  106  is above the threshold fuel pressure. 
         [0021]    Referring to  FIG. 3 , an alternate embodiment of the fuel system  100  is shown. In this embodiment, the priority valve  110  includes a first two-way valve  128  and a second two-way valve  130 . The first two-way valve  128  and the second two-way valve  130  may be an ON-OFF valve. It is contemplated that the first two-way valve  128  and the second two-way valve  130  may be a solenoid-actuated valve, an electro-hydraulic valve, a hydro-mechanical valve or any suitable valve thereof. 
         [0022]    The first two-way valve  128  is positioned such that the first two-way valve  128  is in fluid communication between the fuel supply system  104  and the cooling circuit  108 . In a first position of the first two-way valve  128 , the priority valve  110  restricts the fuel flow to the cooling circuit  108 . In a second position, however, the priority valve  110  allows the fuel flow to the cooling circuit  108 . The controller  114  controls the position of the first two-way valve  128 . The controller  114  switches the first two-way valve  128  in the second position when the pressure between the fuel supply system  104  and the fuel delivery system  106  is above the predetermined threshold fuel pressure. The sensor  112  may then be used to measure the pressure between the fuel supply system  104  and the fuel delivery system  106  and provide input to the controller  114 . 
         [0023]    The second two-way valve  130  is positioned between the first two-way valve  128  and a recirculation line  132  back to the fuel tank  116 . The second two-way valve  130  acts as a pressure-controlling valve for the cooling circuit  108 . As shown in  FIG. 3 , the second two-way valve  130  is pressure-actuated valve, which allows the fuel to flow to the recirculation line  132  and return to the fuel tank  116 , when the pressure in the cooling circuit  108  is above a predetermined value. Thus, the second two-way valve  130  maintains the pressure level in the cooling circuit  108  at relatively lower levels. It may also be contemplated that the second two-way valve  130  may be electrically actuated. In addition, the priority valve  110  and the fuel system  100  may include additional component to enable such functionality. 
         [0024]    Referring to  FIG. 4 , a flow chart  400  is shown, which describes an exemplary method for operation of the fuel system  100  for the internal combustion engine  102 , in accordance with the concepts of the present disclosure.  FIG. 4  is explained in conjunction with the elements from  FIG. 1 ,  FIG. 2 , and  FIG. 3 . The method described in  FIG. 4  starts at step  402 . 
         [0025]    At step  404 , the fuel pump  118  of the fuel supply system  104  pumps fuel from the fuel tank  116  to all components present downstream to the fuel pump  118 . Once the fuel pump  118  pumps fuel, the method moves to step  406 . 
         [0026]    At step  406 , the fuel pump  118  supplies fuel to the fuel delivery system  106  and isolates from the cooling circuit  108  using the priority valve  110 . Once the step  406  is over, the method moves to step  408 . 
         [0027]    At step  408 , the sensor  112  determines the pressure between the first port  120  and the third port  124 , thereby determining the pressure difference between the fuel supply system  104  and the fuel delivery system  106 . Once the pressure is determined the method moves to step  410 . 
         [0028]    At step  410 , the determined pressure is compared with the threshold fuel pressure. If the determined pressure is less than the threshold fuel pressure, the method returns to step  406 . If the determined pressure is greater than the threshold fuel pressure, the method moves to step  412 . 
         [0029]    At step  412 , the fuel pump  118  supplies fuel to the cooling circuit  108  via the second port  122  of the priority valve  110 . The second port  122  is closed/opened using the controller  114 , based on the pressure determined in step  408 . The method may conclude at step  412 . 
       INDUSTRIAL APPLICABILITY 
       [0030]    In operation, the fuel system  100  initiates the supply of fuel from the fuel supply system  104  when the internal combustion engine  102  starts to crank. The fuel pump  118  of the fuel supply system  104  supplies fuel to the priority valve  110 . The priority valve  110  receives the fuel through the first port  120  and directs the fuel from the first port  120  towards the second port  122  and the third port  124 . 
         [0031]    During the cranking of the internal combustion engine  102 , the controller  114  is configured to keep the second port  122  of the priority valve  110  in the closed position. This restricts the fuel flow through the second port  122  into the cooling circuit  108 . The controller  114  further keeps the third port  124  of the priority valve  110  in the open position and allows the fuel flow through the third port  124  to the fuel delivery system  106 . At this stage, the sensor  112  may continuously measure the pressure across the first port  120  and the third port  124  of the priority valve  110 . An input from the sensor  112  is provided to the controller  114 . The controller  114  then facilitates opening of the second port  122 , when the pressure between the fuel supply system  104  and the fuel delivery system  106  is greater than the threshold fuel pressure. This allows the fuel flow through the second port  122  to the cooling circuit  108 . 
         [0032]    Hence, the cranking time may be reduced, as the fuel flow is substantially concentrated at the third port  124  during cranking Therefore, the internal combustion engine  102  may be started in considerably short time durations by building fuel pressure at inlet of a high-pressure pump of the fuel delivery system  106 . 
         [0033]    It should be understood that the above description is intended for illustrative purposes only and is not intended to limit the scope of the present disclosure in any way. Thus, those skilled in the art will appreciate that other aspects of the disclosure can be obtained from a study of the drawings, the disclosure, and the appended claim.