Fuel injection system controlled by the amount of air drawn in during the suction stroke

Claim 2

In a fuel injection system for an internal combustion engine having a crankshaft and an air inflow passage, the fuel-injection system being of the type including at least one electrically operated fuel-injection valve, an arrangement for generating electrical valve-opening pulses, comprising in combination an electronic switch having a conductive and a non-conductive state, and so connected to said valve as to not effect valve opening when in a first state and so as to effect valve opening when in a second state; triggering means connected to said switch for causing the same to undergo a transition to said second state when the engine crankshaft assumes a predetermined position; timing means for determining the length of time said switch remains in said second state and comprising energy-storing timing capacitance means and charging-discharging means connected to said capacitance means and including first means operative for effecting a first change of stored energy of said timing capacitance means when said switch is in said first state and second means operative for effecting an opposite second change of stored energy of said timing capacitance means when said switch is in said second state, with at least said second means being a constant current source means, and with at least one of said first and second means being an adjustable constant current source means, and with said charging-discharging means so connecting said timing capacitance means to said triggering means and to said switch as to cause said switch to return to said first state upon completion of said second change of stored energy; and adjusting means for automatically adjusting said adjustable constant current source means in dependence upon the flow rate of air flowing through said inflow passage.

Claim 3

An arrangement as defined in claim 1, wherein said charging-discharging means comprises means for causing said first means to effect said first energy change during a predetermined fraction of a crankshaft rotation.

Claim 4

An arrangement as defined in claim 1, wherein said charging-discharging means comprises means for causing said first means to effect said first energy change during a fixed fraction of a crankshaft rotation independently of engine speed.

Claim 5

An arrangement as defined in claim 1, wherein said adjustable constant current source means comprises an adjustable resistor, and wherein said adjusting means comprises an airflow sensing member mounted in said passage for displacement by the inflowing air to an extent indicative of the air inflow rate and operatively associated with said adjustable resistor for varying the resistance value of the latter.

Claim 6

An arrangement as defined in claim 4, wherein said adjustable resistor is connected in the current path of said capacitance means and conducts current flowing through said capacitance means during the reSpective one of said energy changes.

Claim 7

An arrangement as defined in claim 4, wherein said adjustable constant current source means comprises an emitter-follower transistor, and wherein said adjustable resistor is connected in the emitter branch of said emitter-follower transistor.

Claim 8

An arrangement as defined in claim 1, wherein said adjustable constant current source means comprises a transistor having a base and having a collector-emitter path connected to said capacitance means for carrying current flowing through said capacitance means during the respective energy change, and bias-adjustment means for varying the voltage at the base of said transistor, and wherein said adjusting means comprises an airflow sensing member mounted in said passage for displacement by the inflowing air to an extent indicative of the air inflow rate and operatively associated with said bias-adjustment means for automatically varying the voltage at the base of said transistor in dependence upon said air inflow rate.

Claim 9

An arrangement as defined in claim 7, wherein said bias-adjustment means comprises a potentiometer having a movable tap connected to said base of said transistor.

Claim 10

An arrangement as defined in claim 1, wherein said adjustable constant current source means is said first means, and wherein said adjusting means comprises means for automatically adjusting the current of said first means to a value proportional to said flow rate, and wherein the operation of said second constant current source means is independent of said flow rate.

Claim 11

An arrangement as defined in claim 1, wherein said capacitor is charged by said first means during said first energy change and is discharged by said second means during said second energy change, and wherein said adjusting means comprises means for automatically adjusting the charging current passing through said capacitance means in dependence upon said flow rate, and wherein the operation of said second means is independent of said flow rate so that the discharge current of said capacitance means is independent of said flow rate.

Claim 12

An arrangement as defined in claim 1, wherein said adjustable constant current source means is said second means, and wherein said adjusting means comprises means for automatically adjusting the current of said second means to a value inversely proportional to said flow rate, and wherein the operation of said first means is independent of said flow rate.

Claim 13

An arrangement as defined in claim 1, wherein said capacitance means is charged by said first means during said first energy change and is discharged by said second means during said second energy change, and wherein said adjusting means comprises means for automatically adjusting the discharging current flowing through said capacitance means to a value inversely proportional to said flow rate, and wherein the operation of said first means is independent of said flow rate so that the discharge current of said capacitance means is independent of said flow rate.

Claim 14

An arrangement as defined in claim 5, wherein said first and second means are respectively operative for charging and discharging said capacitance means, and wherein said adjustable constant current source means is said first means.

Claim 15

An arrangement as defined in claim 5, wherein said first and second means are respectively operative for charging and discharging said capacitance means, and wherein said adjustable constant current source means is said means.

Claim 16

An arrangement as defined in claim 7, wherein said first and second means are respectively operative for charging and discharging said capacitance means, and wherein said adjustable constant current source means is said first means.

Claim 17

An arrangement as defined in claim 7, wherein said first and second means are respectively operative for charging and discharging said capacitance means, and wherein said adjustable constant current source means is said second means.

Claim 18

An arrangement as defined in claIm 1, wherein both said first and said second means are adjustable constant current source means.

Claim 19

An arrangement as defined in claim 1, wherein said adjusting means comprises an airflow sensing member located in said passage and mounted for displacement by the inflowing air to an extent indicative of the air inflow rate, and wherein said sensing member is so mounted so as to reduce the free flow-cross-section of said inflow passage, and wherein said passage and said sensing member are so configurated that as the displacement of said sensing member is increased in equal increments the free flow-cross-section of said inflow passage increases substantially exponentially.

Claim 20

An arrangement as defined in claim 1, wherein said adjusting means comprises an airflow sensing member in said passage mounted for displacement by the inflowing air to an extent indicative of the air inflow rate, and wherein said adjustable constant current source means includes a potentiometer comprising a potentiometer resistor and a movable tap slidable along said potentiometer resistor, with equal increments of movement of said tap along said resistor corresponding to equal-value resistance portions of said potentiometer resistor, and a plurality of further resistors each connected in parallel with a respective portion of said potentiometer resistor and having such values as to impart to said potentiometer an exponential characteristic.

Claim 21

An arrangement as defined in claim 1, wherein said timing capacitance means and said charging-discharging means of said timing means together form a monostable multivibrator having an input transistor and an output transistor of the same conductivity type, with said input transistor and said output transistor being respectively non-conductive and conductive when said multivibrator is in the stable state thereof, a load resistor connecting the collector of said output transistor to one bias-voltage line, and a feedback resistor connecting the collector of said output transistor to the base of said input transistor, and with said timing capacitance means being connected between the collector of said input transistor and the base of said output transistor, and wherein said second means comprises a transistor having a collector connected to one terminal of said timing capacitance means, and having a base connected to the movable tap of an adjustable voltage divider and wherein said first means comprises a transistor having a collector connected to the other terminal of said capacitance means and having a base connected to the center tap of a further voltage divider, and voltage-divider control means for permitting said further voltage divider to bias said transistor of said first means to conductive state only during a predetermined fraction of a crankshaft rotation, with the transistors of said first and second means being of conductivity type opposite to that of said input and output transistors, and further including emitter resistors for said transistors of said first and second means connecting the respective emitters to said one bias-voltage line.

Claim 22

An arrangement as defined in claim 20, wherein said voltage-divider control means comprises a control transistor having a collector connected to one end terminal of said further voltage divider and having an emitter connected to another bias-voltage line, with the other end terminal of said further voltage divider being connected to said one bias-voltage line, and means for applying to the base of said control transistor a voltage sufficient to render the latter conductive only during a predetermined fraction of a crankshaft rotation.

Claim 23

An arrangement as defined in claim 1, wherein said timing capacitance means is a single capacitor.

Claim 24

In a fuel injection arrangement for an internal combustion engine having an electromagnetic fuel injection valve for each cylinder, comprising, in combination, electric storage means; electric circuit means connected to said electric storage means and haVing a first state during which electric energy is added to said electric storage means and a second state during which electric energy is removed from said electric storage means and a fuel injection valve is opened for the period of time required to remove electric energy from said electric storage means, said period of time being dependent on the amount of energy stored and on the rate at which said energy is removed; air meter means associated with the intake manifold of the engine for providing a quantity representative of the time average of the amount of air sucked through the engine intake manifold, and wherein said electric circuit means includes transducer means for making, in dependence on said quantity, an electric parameter of said electric storage means proportional to the amount of air drawn in during each suction stroke of the engine so that said period of time is proportional to said amount of air drawn in during each suction stroke, wherein said electric storage means is a capacitor, and wherein said electric circuit means includes an input transistor and an output transistor, both transistors being of the same conductivity type, the input and output transistors normally being respectively non-conductive and conductive, a load resistor connecting the collector of said output transistor to voltage of one polarity, a feedback resistor connecting said collector to the base of said input transistor, a normally conductive discharge transistor, a first voltage divider connected between voltage of the other polarity and said voltage of one polarity, the tap of said first voltage divider being connected to the base of said discharge transistor, one plate of said capacitor being connected to the collector of said discharge transistor so that the latter conducts the discharge current of said capacitor, a charging transistor, the other plate of said capacitor being connected to the collector of said charging transistor so that the latter can conduct the charging current of said capacitor, a second voltage divider connected to said voltage of one polarity, switch means for connecting said second voltage divider in synchronism with the rotation of the engine crank shaft to said voltage of the other polarity, the tap of said second voltage divider being connected to the base of said charging transistor, said charging transistor and said discharge transistor being of the same conductivity type and opposite to the input and output transistors, and respective resistors connecting the emitters of said charging transistor and said discharge transistor to said voltage of one polarity.

Claim 25

In a fuel injection arrangement for an internal combustion engine having an electromagnetic fuel injection valve for each cylinder, comprising, in combination, electric storage means; electric circuit means connected to said electric storage means and haVing a first state during which electric energy is added to said electric storage means and a second state during which electric energy is removed from said electric storage means and a fuel injection valve is opened for the period of time required to remove electric energy from said electric storage means, said period of time being dependent on the amount of energy stored and on the rate at which said energy is removed; air meter means associated with the intake manifold of the engine for providing a quantity representative of the time average of the amount of air sucked through the engine intake manifold, and wherein said electric circuit means includes transducer means for making, in dependence on said quantity, an electric parameter of said electric storage means proportional to the amount of air drawn in during each suction stroke of the engine so that said period of time is proportional to said amount of air drawn in during each suction stroke, wherein said electric storage means is a capacitor, and wherein said electric circuit means includes an input transistor and an output transistor, both transistors being of the same conductivity type, the input and output transistors normally being respectively non-conductive and conductive, a load resistor connecting the collector of said output transistor to voltage of one polarity, a feedback resistor connecting said collector to the base of said input transistor, a normally conductive discharge transistor, a first voltage divider connected between voltage of the other polarity and said voltage of one polarity, the tap of said first voltage divider being connected to the base of said discharge transistor, one plate of said capacitor being connected to the collector of said discharge transistor so that the latter conducts the discharge current of said capacitor, a charging transistor, the other plate of said capacitor being connected to the collector of said charging transistor so that the latter can conduct the charging current of said capacitor, a second voltage divider connected to said voltage of one polarity, switch means for connecting said second voltage divider in synchronism with the rotation of the engine crank shaft to said voltage of the other polarity, the tap of said second voltage divider being connected to the base of said charging transistor, said charging transistor and said discharge transistor being of the same conductivity type and opposite to the input and output transistors, and respective resistors connecting the emitters of said charging transistor and said discharge transistor to said voltage of one polarity.

Claim 26

The arrangement as defined in claim 23, wherein said switch means includes a switching transistor the collector and emitter of said switching transistor being respectively connected to one end of said second voltage divider and said voltage of the other polarity, said switch means further including signal generator means for making said switching transistor conductive over a predetermined angle of rotation of the crankshaft of the engine.