Patent Publication Number: US-7717077-B2

Title: Internal combustion engine starting system and method

Description:
TECHNICAL FIELD 
     The present invention relates generally to starting systems for internal combustion engines and, more particularly, to an internal combustion engine starting apparatus and method of starting an internal combustion engine that does not require a starter. 
     BACKGROUND OF THE INVENTION 
     Internal combustion engines traditionally require a starting system including a starter to start the engine. As is known, when a user activates an ignition circuit, for example by turning a key or pressing an ignition button, the starter is activated. Upon activation, the function of the starter is two fold. First, the starter turns a fuel pump to provide fuel to the engine. Second, the starter cranks the engine creating suction that draws a fuel/air mixture into a cylinder of the engine for combustion. 
     Traditional Spark Ignited Direct Injection (SIDI) engines have a fuel feed system including a high pressure fuel pump that feeds fuel to the injectors for injection directly into the combustion chamber of the cylinder to be combusted. 
     During SIDI engine operation, the high pressure fuel pump is driven by the engine during engine operation. However, during engine startup, the starter is required initially to turn the high pressure fuel pump to provide the fuel necessary to start the engine. 
     As such, it is desirable to provide a starting system for an internal combustion engine that does not require a starter. 
     SUMMARY OF THE INVENTION 
     In one example embodiment of the present invention, an internal combustion engine starting system including a fuel accumulator instead of a starter is provided. 
     A starting system is provided for delivering pressurized fuel to an engine to start the engine without a starter. The starting system includes an accumulator for storing pressurized fuel during engine operation and engine shut-down. During engine start-up, the accumulator delivers the stored pressurized fuel to the engine to start the engine without a starter. 
     The accumulator is in fluid communication with a low pressure fuel reservoir and the engine. The accumulator includes an accumulator housing that defines an accumulator cavity and includes an accumulator piston and spring assembly, which is moveable longitudinally within the accumulator cavity. 
     A solenoid, in communication with the accumulator, includes a pawl for engagement with a cavity formed in the accumulator piston. The solenoid is operable to selectively engage/disengage the pawl with/from the cavity formed in the accumulator piston to respectively hold the accumulator piston and spring assembly in a fixed position or to release the accumulator piston and spring assembly to move longitudinally within the accumulator cavity. 
     A valve is positioned between the low pressure fuel supply and the accumulator. 
     An electronic control module (ECM) is in electronic communication with the starting system and the engine. The ECM is operable to actuate the valve between an open position, during engine operation, and a closed position, during engine start-up and at engine-shut down. 
     Upon ignition, the ECM is operable to determine which cylinder within the engine has a firing position closest to but not before a top dead center firing position. Upon such determination, the ECM activates the solenoid to disengage the pawl from the accumulator piston, forcing pressurized fuel stored within the accumulator into a high-pressure fuel line for injection into the determined cylinder of the engine. The ECM then initiates a spark into the determined cylinder to generate at least one starting combustion event to start the engine without a starter. 
     The benefits of eliminating the starter from the starting system include decreased initial starting system cost, weight and complexity. Likewise, elimination of the starter would remove a known failure mode, thereby decreasing future service cost and improving customer satisfaction. 
     The above features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a vehicle having an internal combustion engine and a starting system including an accumulator according to one embodiment of the present invention; 
         FIG. 2  is a schematic illustration of the starting system for the internal combustion engine including a detailed illustration of the accumulator according to one embodiment of the present invention; 
         FIG. 3  is a schematic illustration of the starting system including the accumulator according to one embodiment of the present invention at engine start-up; 
         FIG. 4  is a schematic illustration of the starting system including the accumulator according to the embodiment of the present invention illustrated in  FIG. 2  during engine operation; and 
         FIG. 5  is a schematic illustration of the starting system including the accumulator according to the embodiment of the present invention illustrated in  FIG. 2  at engine shut-down. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like reference numbers correspond to like or similar components throughout several figures, in  FIG. 1  a vehicle  10  has an engine  12  operatively connected to a transmission  14 . Transmission  14  has an output member  16  in driving connection with a plurality of wheels (not shown) for transferring power from the engine  12  to the wheels (not shown) to propel the vehicle  10 . Engine  12  may be a Spark Ignited Direct Injection (SIDI) engine, the operation of which is known to those skilled in the art. Engine  12  may be a V-type engine having cylinder bores, not shown, arranged in a V-shaped fashion, or alternately an inline, horizontally opposed, W-type, or other style or design of engine utilizing high-pressure fuel injection. 
     Vehicle  10  includes a low pressure fuel reservoir or tank  18  containing a combustible supply of fuel  20 , for example gasoline. A low-pressure (LP) supply pump  22  is positioned within tank  18  and is operable for moving fuel  20  through a fuel line  24  to a high-pressure (HP) pump assembly  26 . HP pump assembly  26  is operable for rapidly pressurizing fuel  20 , which is delivered to the HP pump assembly  26  by LP supply pump  22  at, for example, approximately 5 bar, to, for example, approximately 150 to 200 bar. Pressurized fuel  20 A is then delivered through a high-pressure fuel line  24 A to a fuel rail  28  having at least one fuel pressure sensor  30  adapted for sensing pressure at fuel rail  28 . From the fuel rail  28 , the pressurized fuel  20 A is directly injected into engine  12  by a plurality of fuel injectors  28 A. 
     An accumulator  32  is in fluid communication with the low pressure fuel reservoir  18  and the fuel rail  28 . The accumulator  32  receives pressurized fuel  20 A from the high-pressure fuel line  24 A and stores the pressurized fuel  20 A during engine operation. The accumulator continues to store pressurized fuel  20 A when the engine  12  is shut-down and is operable to deliver the pressurized fuel  20 A to the plurality of injectors  28 A during engine start-up as illustrated in further detail in  FIG. 3 . 
     In the illustrated embodiment, the pressurized fuel  20 A is stored at an elevated pressure; however, alternatively the pressurized fuel  20 A can be stored at an ambient pressure. 
     An electronic control module (ECM) or controller  36  is in electronic communication with the engine  12 , the transmission  14 , the LP supply pump  22 , the HP pump assembly  26 , the fuel rail  28 , the accumulator  32 , and a valve  34  for control and synchronization of the various starting system and fuel supply components. 
     The valve  34 , for example a check valve or a solenoid, is operable to control a flow of pressurized fuel  20 A within the high-pressure fuel line  24 A. The valve  34  is in an open position during engine operation to allow fuel to flow from the low pressure fuel reservoir  18  to the fuel rail  28  for delivery to the engine  12  by the plurality of fuel injectors  28 A. The valve  34  moves to a closed position upon engine shut-down and remains in the closed position when the engine  12  is shut-down to prevent fuel from flowing from the high-pressure fuel line  24 A back into the low pressure fuel reservoir  18 . 
     As illustrated in  FIG. 2 , the accumulator  32  includes an accumulator housing  38  defining an accumulator cavity  40 . An accumulator piston  42  and an accumulator spring  44  are disposed within the accumulator housing  38 . The accumulator piston  42  includes a pocket  50  for receiving a pawl  52 . A solenoid  54  is operable to selectively engage/disengage the pawl  52 . When the pawl  52  is engaged, the accumulator piston  42  is secured in a fixed position within the accumulator housing  38 . When the pawl  52  is disengaged, the accumulator piston  42  can move longitudinally within the accumulator housing  38 . 
     During engine operation, pressurized fuel  20 A enters the accumulator  32  through an inlet/outlet port  56  and exerts a pressure force P against a front face  46  of the accumulator piston  42 , compressing the accumulator spring  44 , which exerts a spring force S against a rear face  48  of the accumulator piston  42 . The pressurized fuel  20 A is stored by the accumulator  32  within the accumulator cavity  40 . 
     Additionally, to accommodate initial pre-fill and subsequent service, the accumulator  32  can be filled with pressurized fuel  20 A from an external source  58 , for example a fuel fill machine on an assembly line (not shown). 
     At engine start-up, as illustrated in  FIG. 3 , the valve  34  is in the closed position and the accumulator cavity  40  is filled with pressurized fuel  20 A. Upon ignition, the ECM  36  is operable to determine which cylinder  60  of the engine  12  has a firing position closest to but not before a top dead center firing position. That is, the ECM  36  determines an actual firing position of each engine piston  64  within its respective cylinder  60  of the engine  12 . The ECM  36  compares the actual firing position of each engine piston  64  to the top dead center firing position. The ECM  36  then determines the cylinder  60  with the actual firing position closest to but not before the top dead center firing position. 
     Based on the actual firing position of the cylinder  60  closest to the top dead center firing position, the ECM  36  is operable to determine a volume of air contained within the cylinder  60  closest to the top dead center firing position and adjust the amount of pressurized fuel  20 A to be injected accordingly. 
     Upon such determination, the ECM  36  activates the solenoid  54  to disengage the pawl  52  from the accumulator piston  42 , releasing the accumulator piston  42 , allowing the spring force S to overcome the pressure force P. The accumulator piston  42  moves longitudinally within the accumulator cavity  40  forcing the appropriate amount of pressurized fuel  20 A stored within the accumulator cavity  40  into the high-pressure fuel line  24 A. 
     The pressurized fuel  20 A is delivered from the high-pressure fuel line  24 A to an injector  28 A for injection into the determined cylinder  60  of the engine  12 . The ECM  36  initiates a spark into the determined cylinder  60  via a spark plug  62  to generate a first starting combustion event to start the engine  12  without requiring a traditional starter. 
     If, however, the engine  12  does not start after the first starting combustion event or if the fuel pressure sensed by the fuel pressure sensor  30  is not sufficient, the ECM  36  is operable to generate subsequent starting combustion events based upon an accumulator pressure, sensed by an accumulator pressure sensor  66 . Duration of the injection of the pressurized fuel  20 A during the subsequent starting combustion events generated by the ECM  36  is adjusted based upon the sensed accumulator pressure. 
     Referring now to  FIG. 4 , once the engine  12  starts and sufficient fuel pressure is achieved, as determined by the fuel pressure sensed by the at least one fuel pressure sensor  30 , the ECM  36  opens the valve  34  to deliver pressurized fuel  20 A to the engine  12  for continued engine operation. At the same time, a portion of the pressurized fuel  20 A enters the inlet/outlet port  56  to refill the accumulator cavity  40 . The pressure force P of the pressurized fuel  20 A, which is sufficient to overcome the accumulator spring force S, presses against the accumulator piston  42 , moving the accumulator piston  42  longitudinally within the accumulator cavity  40 , compressing the accumulator spring  44 , and allowing the accumulator cavity  40  to fill with pressurized fuel  20 A. 
     Once the accumulator cavity  40  is filled with pressurized fuel  20 A, the ECM  36  activates the solenoid  54  to engage the pawl  52  with the pocket  50  of the accumulator piston  42 , to hold the accumulator piston  42  in a fixed position, storing the pressurized fuel  20 A within the accumulator  32  for use during the next engine start-up. 
     Finally, upon engine shut-down, as illustrated in  FIG. 5 , the ECM  36  closes the valve  34  to prevent the pressurized fuel  20 A stored within the accumulator  32  from flowing back to the low pressure fuel reservoir  18 . The pressurized fuel  20 A is stored within the accumulator  32  until a subsequent engine start-up is initiated by a user. 
     While the best modes for carrying out the 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 within the scope of the appended claims.