Two-cycle utility internal combustion engine

Claim 2

In a two-cycle internal combustion engine, the method of introducing fuel into a cylinder of the engine, which comprises: providing an accumulator-type fuel injector in said two-cycle engine arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; substantially simultaneously pressurizing said accumulator and control cavities with fuel through respective accumulator and control cavity feed conduits to about the same pressure level above that which would be sufficient for the upward force of accumulator pressure on said needle to overcome said spring biasing but for the downward force of control cavity pressure on said needle; at least partially depressurizing said accumulator cavity feed conduit for a substantial portion of the combustion cycle while preventing unrestricted return fuel flow through said accumulator cavity feed conduit from said accumulator cavity; and venting fuel pressure from said control cavity via operation of a two-way solenoid-actuated vent valve in communication with said control cavity so that said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 3

The method of claim 1, wherein a fuel/air mixture in said cylinder is spark-ignited.

Claim 4

The method of claim 2, which comprises fabricating the head and cylinder of said engine as an integral casting; and placing said accumulator-type fuel injector, said two-way solenoid-actuated vent valve, and spark ignition means directly in the head.

Claim 5

The method of claim 2, which comprises hydromechanically producing said pressurizing.

Claim 6

In a two-cycle internal combustion engine, the method of introducing fuel into a cylinder of the engine, which comprises: providing an accumulator-type fuel injector in said two-cycle engine arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; substantially simultaneously pressurizing said accumulator and control cavities with fuel through respective accumulator and control cavity feed conduits to about the same pressure level above that which would be sufficient for the upward force of accumulator pressure on said needle to overcome said spring biasing but for the downward force of control cavity pressure on said needle; at least partially depressurizing said accumulator cavity feed conduit for a substantial portion of the combustion cycle while preventing unrestricted return fuel flow through said accumulator cavity feed conduit from said accumulator cavity; and venting fuel pressure from said control cavity via operation of a two-way solenoid-actuated vent valve in communication with said control cavity so that said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder; wherein said pressurizing and depressurizing steps comprise mechanically reciprocating a high pressure fuel pump plunger in a first direction to produce said pressurizing and in a second direction to produce said depressurizing.

Claim 7

In a two-cycle internal combustion engine, the method of introducing fuel into a cylinder of the engine, which comprises: providing an accumulator-type fuel injector in said two-cycle engine arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; substantially simultaneously pressurizing said accumulator and control cavities with fuel through respective accumulator and control cavity feed conduits to about the same pressure level above that which would be sufficient for the upward force of accumulator pressure on said needle to overcome said spring biasing but for the downward force of control cavity pressure on said needle; at least partially depressurizing said accumulator cavity feed conduit for a substantial portion of the combustion cycle while preventing unrestricted return fuel flow through said accumulator cavity feed conduit from said accumulator cavity; and venting fuel pressure from said control cavity via operation of a two-way solenoid-actuated vent valve in communication with said control cavity so that said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder; wherein said pressurizing and depressurizing steps comprise mechanically reciprocating a high pressure fuel pump plunger in a first direction to produce said pressurizing and in a second direction to produce said depressurizing.

Claim 8

The method of claim 5, which comprises reciprocating said plunger by a cam lobe mechanically driven directly by the engine crankshaft.

Claim 9

The method of claim 6, wherein said cam lobe is located directly on the crankshaft.

Claim 10

The method of claim 5, which comprises reciprocating said plunger so that the pump pressure output produced by the motion of said plunger rises from a predetermined low pressure to a predetermined peak pressure.

Claim 11

The method of claim 9, wherein the motion of said plunger, when plotted against time, generally follows a sine curve.

Claim 12

The method of claim 8, which comprises pressure-relieving said pump pressure output at a maximum pressure slightly below said peak pressure so as to assure a uniform said maximum pressure in said pressurizing of said accumulator cavity and said control cavity despite manufacturing tolerances.

Claim 13

The method of claim 8, which comprises placing a check valve in said accumulator cavity feed conduit, so that the highest pump output pressure received will be retained in said accumulator cavity until venting of said control cavity by said solenoid vent valve, if said venting is timed to occur proximate or after pressure in said accumulator cavity has risen to said highest pressure.

Claim 14

The method of claim 12, which comprises placing a flow-restricting orifice in said control cavity feed conduit so that fuel inflow through said control cavity feed conduit during control cavity venting does not interfere with solenoid vent valve venting of said control cavity.

Claim 15

The method of claim 12, wherein said orifice is a variable orifice.

Claim 16

The method of claim 11, wherein said solenoid valve is timed to vent said control cavity proximate or after the time that pressure in said accumulator cavity has risen to said highest pressure, providing a maximum injected fuel mass.

Claim 17

The method of claim 12, wherein said solenoid vent valve is timed to vent said control cavity before pressure in said accumulator cavity has risen to said highest pressure, providing a reduced injected fuel mass.

Claim 18

The method of claim 8, which comprises placing a check valve in said control cavity feed conduit so that the highest pump output pressure received will be retained in said control cavity until venting of said control cavity by said solenoid vent valve.

Claim 19

The method of claim 16, which comprises placing a flow-restricting orifice in said accumulator cavity feed conduit so as to minimize fuel backflow from said accumulator cavity during injection events, and so that the "effective" accumulator cavity volume during injection remains generally the same as the actual volume of said accumulator cavity.

Claim 20

The method of claim 16, wherein said solenoid vent valve is timed to vent said control cavity proximate the time that pressure in said accumulator cavity has risen to the highest pump output pressure received, providing a maximum injected fuel mass.

Claim 21

The method of claim 16, wherein said solenoid vent valve is timed to vent said control cavity either before or after pressure in said accumulator cavity has risen to the highest pump output pressure receivable by said accumulator cavity, providing a reduced injected fuel mass.

Claim 22

The method of claim 8, which comprises placing a flow-restricting orifice in each of said accumulator cavity and control cavity feed conduits, so as to minimize fuel inflow through said control cavity feed conduit during control cavity venting and so as to minimize fuel backflow through the accumulator cavity feed conduit, whereby fuel inflow through said control cavity feed conduit does not interfere with solenoid vent valve venting of said control cavity, and the "effective" accumulator cavity volume during injection remains generally the same as the actual volume of said accumulator cavity.

Claim 23

The method of claim 20, wherein said solenoid vent valve is timed to vent said control cavity proximate the time that pressure in said accumulator cavity has risen to the highest pump output pressure received, providing a maximum injected fuel mass.

Claim 24

The method of claim 20, wherein said solenoid vent valve is timed to vent said control cavity either before or after pressure in said accumulator cavity has risen to the highest pump output pressure receivable by said accumulator cavity, providing a reduced injected fuel mass.

Claim 25

The method of claim 9, which comprises placing a check valve in each of said accumulator cavity and control cavity feed conduits, so that the highest pump output pressure received will be retained in both of said accumulator cavity and said control cavity until venting of said control cavity by said solenoid vent valve, if said venting is timed to occur proximate or after pressure in said accumulator cavity has risen to said highest pressure.

Claim 26

The method of claim 23, wherein said solenoid vent valve is timed to vent said control cavity proximate or after the time that pressure in said accumulator cavity has risen to said highest pressure, providing a maximum injected fuel mass.

Claim 27

The method of claim 23, wherein said solenoid vent valve is timed to vent said control cavity before pressure in said accumulator cavity has risen to said highest pressure, providing a reduced injected fuel mass.

Claim 28

In a two-cycle internal combustion engine, the method of introducing fuel into a cylinder of the engine, which comprises: providing an accumulator-type fuel injector in said two-cycle engine arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; substantially simultaneously pressurizing said accumulator and control cavities with fuel through respective accumulator and control cavity feed conduits to about the same pressure level above that which would be sufficient for the upward force of accumulator pressure on said needle to overcome said spring biasing but for the downward force of control cavity pressure on said needle; at least partially depressurizing said accumulator cavity feed conduit for a substantial portion of the combustion cycle while preventing unrestricted return fuel flow through said accumulator cavity feed conduit from said accumulator cavity; and venting fuel pressure from said control cavity via operation of a two-way solenoid-actuated vent valve in communication with said control cavity so that said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder; wherein said pressurizing and depressurizing steps are performed by a reciprocating plunger high pressure pump, wherein the pump pressure output produced by the motion of said plunger rises from a predetermined low pressure to a predetermined peak pressure and then falls back to said predetermined low pressure, wherein said step of preventing unrestricted return fuel flow comprises providing a flow-restriction device in said accumulator cavity feed conduit to limit fuel backflow toward said pump so as to maintain accumulator pressure substantially higher than control cavity pressure prior to injection, injection being initiated by venting of said control cavity by backflow of fuel from said control cavity toward the pump as pressure thus falls back from said peak pressure toward said low pressure.

Claim 29

In a two-cycle internal combustion engine, the method of introducing fuel into a cylinder of the engine, which comprises: providing an accumulator-type fuel injector in said two-cycle engine arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; substantially simultaneously pressurizing said accumulator and control cavities with fuel through respective accumulator and control cavity feed conduits to about the same pressure level above that which would be sufficient for the upward force of accumulator pressure on said needle to overcome said spring biasing but for the downward force of control cavity pressure on said needle; at least partially depressurizing said accumulator cavity feed conduit for a substantial portion of the combustion cycle while preventing unrestricted return fuel flow through said accumulator cavity feed conduit from said accumulator cavity; and venting fuel pressure from said control cavity via operation of a two-way solenoid-actuated vent valve in communication with said control cavity so that said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder; wherein said pressurizing and depressurizing steps are performed by a reciprocating plunger high pressure pump, wherein the pump pressure output produced by the motion of said plunger rises from a predetermined low pressure to a predetermined peak pressure and then falls back to said predetermined low pressure, wherein said step of preventing unrestricted return fuel flow comprises providing a flow-restriction device in said accumulator cavity feed conduit to limit fuel backflow toward said pump so as to maintain accumulator pressure substantially higher than control cavity pressure prior to injection, injection being initiated by venting of said control cavity by backflow of fuel from said control cavity toward the pump as pressure thus falls back from said peak pressure toward said low pressure.

Claim 30

The method of claim 26, wherein said flow-restriction device comprises a check valve, providing a maximum injected fuel mass.

Claim 31

The method of claim 2, which comprises varying the power output of said engine by skip-firing, said skip-firing being accomplished by causing noninjection of fuel in the engine cylinder during one or more engine crankshaft cycles during a series of a predetermined number of crankshaft cycles.

Claim 32

The method of claim 28, which comprises causing said noninjection by one of (a) not venting said control cavity and (b) venting said control cavity early in the combustion cycle to prevent fuel pressurization of the accumulator and control cavities.

Claim 33

The method of claim 28, wherein the engine power is varied from idle to full power.

Claim 34

The method of claim 28, which comprises causing said skip-firing by utilizing a cascade counting circuit in pulse divider logic circuitry of an engine ECU.

Claim 35

The method of claim 28, which comprises providing four engine power settings ranging from idle to full power.

Claim 36

The method of claim 28, which comprises providing six engine power settings ranging from idle to full power.

Claim 37

The method of claim 8, wherein said engine is piston-ported, and which comprises timing said solenoid vent valve to cause initiation of injection generally proximate engine BDC when the piston is generally proximate its lowest position in the cylinder, and tailoring the injection spray such that the piston has risen after BDC to a position where it substantially closes the engine exhaust port by the time the injection spray front reaches the exhaust port, so as to substantially prevent escape of unburned fuel droplets out through the exhaust port.

Claim 38

The method of claim 34, which comprises timing said solenoid vent valve to cause initiation of injection to vent said control cavity proximate the time that pressure in said accumulator cavity has risen to the highest pump output pressure received, providing a maximum injected fuel mass.

Claim 39

The method of claim 34, which comprises timing said solenoid vent valve to vent said control cavity either before or after pressure in said accumulator cavity has risen to the highest pump output pressure receivable by said accumulator cavity, providing a reduced injected fuel mass.

Claim 40

The method of claim 8, wherein said engine is piston-ported, and which comprises timing said solenoid vent valve to cause initiation of injection generally proximate engine BDC when the piston is generally proximate its lowest position in the cylinder, and tailoring the injection spray such that when the piston has risen after BDC to a position where it substantially closes the engine exhaust port, the injection spray front is still spaced substantially above the piston, whereby a pocket of intake air will be captured within the cylinder between the spray front and the piston so as to provide stratified charge combustion.

Claim 41

The method of claim 2, which comprises providing a magneto located proximate the engine flywheel and electrically energized by a permanent magnet peripherally located on the flywheel, and an electrically energizing spark igniter in the engine head energized by high voltage output from said magneto.

Claim 42

The method of claim 38, which comprises periodically actuating said solenoid vent valve to periodically vent said control cavity to initiate a series of injections by a periodic electrical pulse output from an ECU, and electrically energizing said ECU by an electrical output from a charging coil associated with said magneto.

Claim 43

The method of claim 39, wherein said charging coil comprises the primary winding of said magneto.

Claim 44

The method of claim 39, wherein said charging coil comprises a separate charging coil.

Claim 45

The method of claim 39, which comprises timing said ECU by an electrical pulse output from an engine position and speed sensor located proximate the engine flywheel and electrically energized by said permanent magnet.

Claim 46

The method of claim 39, which comprises varying engine power by skip-firing accomplished by causing the ECU to periodically one of (a) not actuate said solenoid vent valve and (b) vent said control cavity early in the combustion cycle to prevent fuel pressurization of the accumulator and control cavities, and commanding the ECU to cause such skip-firing by an engine load command device having an electrical output connected to the ECU.

Claim 47

The method of claim 43, wherein said electrical output is digital.

Claim 48

The method of claim 43, wherein said electrical output is analog.

Claim 49

The method of claim 10, wherein said pressure relieving of said pump pressure output is accomplished by a variable pressure relief valve comprising a spring-biased closure device, and varying the spring-biasing force on said closure device so as to vary said pump output maximum pressure.

Claim 50

The method of claim 46, wherein said varying of the spring-biasing force is accomplished by a trigger actuator.

Claim 51

The method of claim 8, which comprises boosting the pump fuel input by a fuel transfer pump in the pump fuel input.

Claim 52

The method of claim 48, which comprises varying the fuel pressure output of said transfer pump so as to vary the high pressure pump output pressure.

Claim 53

The method of claim 49, wherein said varying of the fuel pressure output of said transfer device is commanded by an ECU.

Claim 54

A two-cycle internal combustion engine, which comprises: an accumulator-type fuel injector mounted in the two-cycle engine and arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; a source of fuel; a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through respective accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle, said accumulator cavity. feed conduit having a device located therein to prevent unrestricted return fuel flow therethrough when said accumulator cavity feed conduit is depressurized; and a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 55

A two-cycle internal combustion engine, which comprises: an accumulator-type fuel injector mounted in the two-cycle engine and arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; a source of fuel; a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through respective accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle, said accumulator cavity. feed conduit having a device located therein to prevent unrestricted return fuel flow therethrough when said accumulator cavity feed conduit is depressurized; and a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 56

The apparatus of claim 51, which comprises spark ignition means in said engine head for igniting a fuel/air mixture in said engine cylinder.

Claim 57

The apparatus of claim 52, wherein the head and cylinder of said engine comprise an integral casting; said accumulator-type fuel injector, said two-way solenoid-actuated valve, and said spark ignition means all being located in said head.

Claim 58

The apparatus of claim 52, wherein said pump is mechanically driven by the engine crankshaft.

Claim 59

The apparatus of claim 54, wherein said pump comprises a mechanically actuated reciprocating plunger pump.

Claim 60

The apparatus of claim 55, which further comprises a cam lobe operatively engaged against one end of said plunger for reciprocating said plunger, the other end of said plunger operating to pressurize fuel when it rises under the influence of said cam lobe.

Claim 61

The apparatus of claim 56, wherein said cam lobe is located directly on the crankshaft.

Claim 62

The apparatus of claim 56, wherein said cam lobe reciprocates said plunger so that the pump pressure output produced by the motion of said plunger rises from a predetermined low pressure to a predetermined peak pressure.

Claim 63

The apparatus of claim 58, wherein the motion of said plunger when plotted against time, generally follows a sine curve.

Claim 64

The apparatus of claim 58, which comprises a pressure relief valve in fluid communication with said pump output and set to pressure-relieve the pump output at a maximum pressure slightly below said peak pressure so as to assure a uniform said maximum pressure in said pressurizing of said accumulator cavity and said control cavity despite manufacturing tolerances.

Claim 65

The apparatus of claim 58, wherein said device in said accumulator cavity feed conduit comprises a check valve, whereby the highest pump output pressure received will be retained in said accumulator cavity until venting of said control cavity by said solenoid vent valve, if said venting is timed to occur proximate or after pressure in said accumulator cavity has risen to said highest pressure.

Claim 66

The apparatus of claim 61, which comprises a flow-restricting orifice in said control cavity feed conduit, whereby fuel inflow through said control cavity feed conduit during control cavity venting does not interfere with solenoid valve venting of said control cavity.

Claim 67

The apparatus of claim 61, wherein said orifice is a variable orifice.

Claim 68

The apparatus of claim 61, wherein said solenoid vent valve is timed to vent said control cavity proximate or after the time that pressure in said accumulator cavity has risen to said highest pressure, providing a maximum injected fuel mass.

Claim 69

The apparatus of claim 61, wherein said solenoid vent valve is timed to vent said control cavity before pressure in said accumulator cavity has risen to said highest pressure, providing a reduced injected fuel mass.

Claim 70

The apparatus of claim 58, which comprises a check valve in said control cavity feed conduit, whereby the highest pump output pressure received will be retained in said control cavity until venting of said control cavity by said solenoid vent valve.

Claim 71

The apparatus of claim 66, wherein said device in said accumulator cavity feed conduit comprises a flow-restricting orifice, whereby fuel backflow from said accumulator cavity is minimized during injection events, and the "effective" accumulator cavity volume during injection remains generally the same as the actual volume of said accumulator cavity.

Claim 72

The apparatus of claim 66, wherein said solenoid vent valve is timed to vent said control cavity proximate the time that pressure in said accumulator cavity has risen to the highest pump output pressure received, providing a maximum injected fuel mass.

Claim 73

The apparatus of claim 66, wherein said solenoid vent valve is timed to vent said control cavity either before or after pressure in said accumulator cavity has risen to the highest pump output pressure receivable by said accumulator cavity, providing a reduced injected fuel mass.

Claim 74

The apparatus of claim 58, wherein said device in said accumulator cavity feed conduit comprises a flow restricting orifice, and further comprising a flow-restricting orifice in the control cavity feed conduit, thereby minimizing fuel inflow through said control cavity feed conduit during control cavity venting and so as to minimize fuel backflow through the accumulator cavity feed conduit, whereby fuel inflow through said control cavity feed conduit does not interfere with solenoid vent valve venting of said control cavity, and the "effective" accumulator cavity volume during injection remains generally the same as the actual volume of said accumulator cavity.

Claim 75

The apparatus of claim 70, wherein said solenoid vent valve is timed to vent said control cavity proximate the time that pressure in said accumulator cavity has risen to the highest pump output pressure received, providing a maximum injected fuel mass.

Claim 76

The apparatus of claim 73, wherein said solenoid vent valve is timed to vent said control cavity either before or after pressure in said accumulator cavity has risen to the highest pump output pressure receivable by said accumulator cavity, providing a reduced injected fuel mass.

Claim 77

The apparatus of claim 58, wherein said device in said accumulator cavity feed conduit comprises a check valve, and further comprising a check valve in said control cavity feed conduit, whereby the highest pump output pressure received will be retained in both of said accumulator cavity and said control cavity until venting of said control cavity by said solenoid vent valve, if said venting is timed to occur proximate or after pressure in said accumulator cavity has risen to said highest pressure.

Claim 78

The apparatus of claim 73, wherein said solenoid vent valve is timed to vent said control cavity proximate or after the time that pressure in said accumulator cavity has risen to said highest pressure, providing a maximum injected fuel mass.

Claim 79

The apparatus of claim 73, wherein said solenoid vent valve is timed to vent said control cavity before pressure in said accumulator cavity has risen to said highest pressure, providing a reduced fuel mass.

Claim 80

A two-cycle internal combustion engine, which comprises: an accumulator-type fuel injector mounted in the two-cycle engine and arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; a source of fuel; a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through respective accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle, said accumulator cavity feed conduit having a device located therein to prevent unrestricted return fuel flow therethrough when said accumulator feed conduit is depressurized, wherein said pump comprises a reciprocating plunger high pressure pump, wherein the pump pressure output produced by the motion of said plunger rises from a predetermined low pressure to a predetermined peak pressure and then falls back to said predetermined low pressure, injection being initiated by venting of said control cavity by venting of fuel from said control cavity toward the pump as pressure thus falls back from said peak pressure toward said low pressure, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 81

A two-cycle internal combustion engine, which comprises: an accumulator-type fuel injector mounted in the two-cycle engine and arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; a source of fuel; a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through respective accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle, said accumulator cavity feed conduit having a device located therein to prevent unrestricted return fuel flow therethrough when said accumulator feed conduit is depressurized, wherein said pump comprises a reciprocating plunger high pressure pump, wherein the pump pressure output produced by the motion of said plunger rises from a predetermined low pressure to a predetermined peak pressure and then falls back to said predetermined low pressure, injection being initiated by venting of said control cavity by venting of fuel from said control cavity toward the pump as pressure thus falls back from said peak pressure toward said low pressure, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 82

The apparatus of claim 76, wherein said flow restriction comprises a check valve, providing a maximum injected fuel mass.

Claim 83

The apparatus of claim 52, which comprises ECU means, electrically connected to said solenoid vent valve, for periodically energizing said solenoid vent valve to cause venting of said control cavity and consequent initiation of injection; and engine load command input means, electrically connected to said ECU means, for causing said ECU means to one of (a) nonenergize said solenoid vent valve and (b) vent said control cavity early in the combustion cycle so as to prevent fuel pressurization of the accumulator and control cavities and thereby to cause skip-firing by noninjection of fuel in the engine cylinder during one or more engine crankshaft cycles during a series of predetermined number of crankshaft cycles, thereby reducing the engine power output from full power.

Claim 84

The apparatus of claim 78, wherein said load command input causes said ECU means to vary engine power from idle to full power.

Claim 85

The apparatus of claim 79, wherein said ECU means comprises a cascade counting circuit.

Claim 86

The apparatus of claim 78, wherein said load command input causes said ECU means to provide four engine power settings ranging from idle to full power.

Claim 87

The apparatus of claim 78, wherein said load command input causes said ECU means to provide six engine power settings ranging from idle to full power.

Claim 88

The apparatus of claim 58, wherein said engine is piston-ported, and which comprises ECU, electrically connected to said solenoid vent valve means, for causing venting of said control cavity and consequent initiation of injection; said ECU means timing said solenoid vent valve to cause initiation of injection generally proximate engine BDC when the piston is generally proximate its lowest position in the cylinder, and tailoring the injection spray such that the piston has risen after BDC to a position where it substantially closes the engine exhaust port by the time the injection spray front reaches the exhaust port, so as to substantially prevent escape of unburned fuel droplets out through the exhaust port.

Claim 89

The apparatus of claim 83, wherein said ECU means times said solenoid vent valve to cause initiation of injection to vent said control cavity proximate the time that pressure in said accumulator cavity has risen to the highest pump output pressure received, providing a maximum injected fuel mass.

Claim 90

The apparatus of claim 83, wherein said ECU means times said solenoid vent valve to vent said control cavity either before or after pressure in said accumulator cavity has risen to the highest pump output pressure receivable by said accumulator cavity, providing a reduced injected fuel mass.

Claim 91

The apparatus of claim 58, wherein said engine is piston-ported, and which comprises ECU means, electrically connected to said solenoid vent valve, for timing energization of said solenoid vent valve to periodically vent said control cavity to initiate injection, said ECU timing energization of said solenoid vent valve to cause initiation of injection generally proximate engine BDC when the piston is generally proximate its lowest position in the cylinder; said accumulator fuel injector being configured to tailor the injection spray such that when the piston has risen after BDC to a position where it substantially closes the engine exhaust port, the injection spray front is still spaced substantially above the piston, whereby a pocket of intake air will be captured within the cylinder between the spray front and the piston so as to provide stratified charge combustion.

Claim 92

The apparatus of claim 52, which comprises a permanent magnet peripherally located on the flywheel, a magneto located proximate the engine flywheel and electrically energized by said permanent magnet, and an electrically energized spark ignition device in the engine head energized by high voltage output from said magneto.

Claim 93

The apparatus of claim 87, which comprises ECU means, electrically connected to said solenoid vent valve, for periodically energizing said solenoid vent valve to cause venting of said control cavity and consequent initiation of injection; and changing coil means, associated with said magneto and electrically connected to said ECU means, for electrically energizing said ECU.

Claim 94

The apparatus of claim 88, wherein said charging coil comprises the primary winding of said magneto.

Claim 95

The apparatus of claim 88, wherein said charging coil means comprises a separate charging coil.

Claim 96

The apparatus of claim 88, which comprises an engine position and speed sensor located proximate the engine flywheel and electrically energized by said permanent magnet, said position and speed sensor having an electrical pulse output connected to said ECU means for timing said ECU means.

Claim 97

The apparatus of claim 88, which comprises engine load command input electrically connected to said ECU means, for causing said ECU means to one of (a) nonenergize said solenoid vent valve and (b) vent said control cavity early in the combustion cycle to prevent fuel pressurization of the accumulator and control cavities so as to cause skip-firing by noninjection of fuel in the engine cylinder during one or more engine crankshaft cycles during a series of a predetermined number of crankshaft cycles, thereby reducing the engine power output from full power.

Claim 98

The apparatus of claim 92, wherein said load command input provides a digital command to said ECU means.

Claim 99

The apparatus of claim 92, wherein said load command input provides an analog command to said ECU means.

Claim 100

The apparatus of claim 60, wherein said pressure relief valve comprises a spring-biased closure device, and means, operatively associated with said biasing spring, for varying the spring force applied to said closure device so as to vary said pump output maximum pressure.

Claim 101

The apparatus of claim 95, wherein said spring force varying device comprises a trigger actuator.

Claim 102

The apparatus of claim 58, which comprises a fuel transfer pump means, operatively associated with said high pressure pump input, for boosting the pressure of fuel supplied to said input.

Claim 103

The apparatus of claim 97, wherein said transfer pump means has a variable pressure output so as to vary the high pressure pump output pressure.

Claim 104

The apparatus of claim 98, which comprises ECU means, electrically connected to said fuel transfer pump means, for commanding variation of the output pressure of said fuel transfer pump means.

Claim 111

A two-cycle internal combustion engine which comprises: (A) an accumulator-type fuel injector mounted in said two-cycle engine and arranged for direct in-cylinder injection, said injector having (1) a needle normally spring-biased downwardly to a closed position, (2) an accumulator cavity (a) located so as to provide an upward opening force on said needle when pressurized and (b) receiving pressurized fuel via an accumulator cavity feed conduit, (3) a check valve disposed in said accumulator cavity feed conduit and permitting fuel flow into said accumulator cavity from said pump but preventing reverse flow therethrough, (3) a control cavity (a) located above said needle so as to provide a downward closing force on said needle when pressurized, and (b) receiving pressurized fuel via a control cavity feed conduit, and (4) a flow-restricting orifice provided in said control cavity feed conduit; (B) a source of fuel; (C) a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through the accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle; and (D) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder, and whereby, due to the presence of said flow-restricting orifice, fuel inflow through said control cavity feed conduit does not interfere with solenoid vent valve venting of said control cavity.

Claim 112

A two-cycle internal combustion engine which comprises: (A) an accumulator-type fuel injector mounted in said two-cycle engine and arranged for direct in-cylinder injection, said injector having (1) a needle normally spring-biased downwardly to a closed position, (2) an accumulator cavity (a) located so as to provide an upward opening force on said needle when pressurized and (b) receiving pressurized fuel via an accumulator cavity feed conduit, (3) a check valve disposed in said accumulator cavity feed conduit and permitting fuel flow into said accumulator cavity from said pump but preventing reverse flow therethrough, (3) a control cavity (a) located above said needle so as to provide a downward closing force on said needle when pressurized, and (b) receiving pressurized fuel via a control cavity feed conduit, and (4) a flow-restricting orifice provided in said control cavity feed conduit; (B) a source of fuel; (C) a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through the accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle; and (D) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder, and whereby, due to the presence of said flow-restricting orifice, fuel inflow through said control cavity feed conduit does not interfere with solenoid vent valve venting of said control cavity.

Claim 113

A two-cycle internal combustion engine which comprises: (A) an accumulator-type fuel injector mounted in said two-cycle engine and arranged for direct in-cylinder injection, said injector having (1) a needle normally spring-biased downwardly to a closed position, (2) an accumulator cavity (a) located so as to provide an upward opening force on said needle when pressurized and (b) receiving pressurized fuel via an accumulator cavity feed conduit, and (3) a control cavity (a) located above said needle so as to provide a downward closing force on said needle when pressurized, and (b) receiving pressurized fuel via a control cavity feed conduit; (B) a source of fuel; (C) a reciprocating plunger type high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through the accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle; (D) a cam lobe, mounted directly on the engine crankshaft, which reciprocates the plunger of said pump so that the pump pressure output produced by said plunger rises from a predetermined low pressure to a predetermined peak pressure; (E) a pressure relief valve comprising a spring-biased closure device in fluid communication with said pump output and set to pressure-relieve said pump output at a maximum pressure slightly below said peak pressure so as to assure a uniform pressurization of said accumulator cavity and said control cavity despite manufacturing tolerances; (F) means for varying the spring biasing force on said closure device so as to vary said pump output maximum pressure; and (G) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 114

A two-cycle internal combustion engine which comprises: (A) an accumulator-type fuel injector mounted in said two-cycle engine and arranged for direct in-cylinder injection, said injector having (1) a needle normally spring-biased downwardly to a closed position, (2) an accumulator cavity (a) located so as to provide an upward opening force on said needle when pressurized and (b) receiving pressurized fuel via an accumulator cavity feed conduit, and (3) a control cavity (a) located above said needle so as to provide a downward closing force on said needle when pressurized, and (b) receiving pressurized fuel via a control cavity feed conduit; (B) a source of fuel; (C) a reciprocating plunger type high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through the accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle; (D) a cam lobe, mounted directly on the engine crankshaft, which reciprocates the plunger of said pump so that the pump pressure output produced by said plunger rises from a predetermined low pressure to a predetermined peak pressure; (E) a pressure relief valve comprising a spring-biased closure device in fluid communication with said pump output and set to pressure-relieve said pump output at a maximum pressure slightly below said peak pressure so as to assure a uniform pressurization of said accumulator cavity and said control cavity despite manufacturing tolerances; (F) means for varying the spring biasing force on said closure device so as to vary said pump output maximum pressure; and (G) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 115

A two-cycle internal combustion engine which comprises: (A) an accumulator-type fuel injector mounted in said two-cycle engine and arranged for direct in-cylinder injection, said injector having (1) a needle normally spring-biased downwardly to a closed position, (2) an accumulator cavity (a) located so as to provide an upward opening force on said needle when pressurized and (b) receiving pressurized fuel via an accumulator cavity feed conduit, and (3) a control cavity (a) located above said needle so as to provide a downward closing force on said needle when pressurized, and (b) receiving pressurized fuel via a control cavity feed conduit; (B) a source of fuel; (C) a reciprocating plunger type high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through the accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle; (D) a cam lobe, mounted directly on the engine crankshaft, which reciprocates the plunger of said pump so that the pump pressure output produced by said plunger rises from a predetermined low pressure to a predetermined peak pressure; (E) a fuel transfer pump means, operatively associated with said high pressure pump input, for boosting the pressure of fuel supplied to said pump input, said pump transfer means having a variable pressure output so as to vary the high pressure pump output pressure; and (F) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 116

A two-cycle internal combustion engine which comprises: (A) an accumulator-type fuel injector mounted in said two-cycle engine and arranged for direct in-cylinder injection, said injector having (1) a needle normally spring-biased downwardly to a closed position, (2) an accumulator cavity (a) located so as to provide an upward opening force on said needle when pressurized and (b) receiving pressurized fuel via an accumulator cavity feed conduit, and (3) a control cavity (a) located above said needle so as to provide a downward closing force on said needle when pressurized, and (b) receiving pressurized fuel via a control cavity feed conduit; (B) a source of fuel; (C) a reciprocating plunger type high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through the accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle; (D) a cam lobe, mounted directly on the engine crankshaft, which reciprocates the plunger of said pump so that the pump pressure output produced by said plunger rises from a predetermined low pressure to a predetermined peak pressure; (E) a fuel transfer pump means, operatively associated with said high pressure pump input, for boosting the pressure of fuel supplied to said pump input, said pump transfer means having a variable pressure output so as to vary the high pressure pump output pressure; and (F) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder.

Claim 121

A two-cycle internal combustion engine, which comprises: (A) an accumulator-type fuel injector mounted in the two-cycle engine and arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator control cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; (B) a source of fuel; (C) a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through respective accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle, said accumulator cavity feed conduit having a flow restriction device located therein to prevent unrestricted return fuel flow therethrough from said accumulator cavity when said accumulator cavity feed conduit is depressurized; (D) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder, wherein said pump comprises a mechanically actuated reciprocating plunger pump driven by an eccentric circular cam which is mounted directly on the engine crankshaft and which provides a motion to said plunger which, when plotted against time, generally follows a sine curve having a period equal to a sine curve followed by the engine piston; and (E) means for controlling energization of said solenoid vent valve such that the quantity of fuel injected and the timing of fuel injection are dependent upon the timing of solenoid vent valve opening relative to pump plunger position.

Claim 122

A two-cycle internal combustion engine, which comprises: (A) an accumulator-type fuel injector mounted in the two-cycle engine and arranged for direct in-cylinder injection, said injector having a needle normally spring-biased downwardly to a closed position, an accumulator control cavity located so as to provide an upward opening force on said needle when pressurized, and a control cavity above said needle located so as to provide a downward closing force on said needle when pressurized; (B) a source of fuel; (C) a high pressure fuel pump having an input operatively connected to said fuel source and having an output in fluid communication with said accumulator and control cavities through respective accumulator and control cavity feed conduits so as to substantially simultaneously and periodically provide pressurized fuel at about the same pressure level to said accumulator and control cavities and to periodically at least partially depressurize at least a portion of said accumulator cavity feed conduit for a substantial portion of the combustion cycle, said pressure level being sufficient for the upward force of accumulator pressure on said needle to overcome said spring-biasing but for the downward force of control cavity pressure on said needle, said accumulator cavity feed conduit having a flow restriction device located therein to prevent unrestricted return fuel flow therethrough from said accumulator cavity when said accumulator cavity feed conduit is depressurized; (D) a two-way solenoid-actuated vent valve, in fluid communication with said control cavity, for periodically venting fuel pressure from said control cavity, whereby upon such venting said upward force of accumulator pressure on said needle overcomes said downward forces on said needle and raises said needle to an open position for injection of fuel from said accumulator injector directly into the cylinder, wherein said pump comprises a mechanically actuated reciprocating plunger pump driven by an eccentric circular cam which is mounted directly on the engine crankshaft and which provides a motion to said plunger which, when plotted against time, generally follows a sine curve having a period equal to a sine curve followed by the engine piston; and (E) means for controlling energization of said solenoid vent valve such that the quantity of fuel injected and the timing of fuel injection are dependent upon the timing of solenoid vent valve opening relative to pump plunger position.

Claim 125

A method as defined in claim 109, further comprising maintaining a generally constant volume of injected fuel during each injection event at all engine output power settings.