Load dependent control circuit for a gasoline fuel injection unit

Claim 2

A control circuit for regulating the open period of at least one fuel injection valve of an internal combustion engine, comprising, in combination trigger circuit means for producing electric valve-opening pulses for opening the fuel injection valve; regulating circuit means, connected to said trigger circuit means, for delivering a control voltage that periodically varies in time with said pulses for varying the duration of said pulses in dependence on engine speed; and time delay circuit means, connected to said trigger circuit means, operative when said pulses exceed a predetermined pulse-length, for so negating the effect of said control voltage when the engine is working at full load that the open time of said fuel injection valve is suited to full load operation of the engine.

Claim 3

A control circuit for regulating the open period of at least one fuel injection valve of an internal combustion engine, comprising, in combination, trigger circuit means for producing electric valve-opening pulses for opening the fuel injection valve; regulating circuit means connected to said trigger circuit means for varying the pulse-duration of said valve-opening pulses in dependence upon at least one engine operating condition according to a first predetermined functional relationship; and compensating means, operative only after a predetermined time delay relative to the beginning of each valve-opening pulse, for altering said regulating circuit in such a manner as to effect a changeover to a second predetermined functional relationship appropriate for full-load operation of said engine, said compensating means accordingly participating in the determination of the pulse-duration of valve-opening pulses only when such valve-opening pulses have a duration exceeding said predetermined time delay.

Claim 4

A control circuit for regulating the open period of at least one fuel injection valve of an internal combustion engine, comprising, in combination, trigger circuit means for producing electric valve-opening pulses for opening the fuel injection valve; regulating circuit means connected to said trigger circuit means for varying the pulse-duration of said valve-opening pulses in dependence upon at least one engine operating condition according to a first predetermined functional relationship; and compensating means, operative only after a predetermined time delay relative to the beginning of each valve-opening pulse, for altering said regulating circuit in such a manner as to effect a changeover to a second predetermined functional relationship appropriate for full-load operation of said engine, said compensating means accordingly participating in the determination of the pulse-duration of valve-opening pulses only when such valve-opening pulses have a duration exceeding said predetermined time delay.

Claim 5

In a combustion engine as defined in claim 1, wherein said regulating circuit means comprises means for timing the lengths of said pulses as a function of airflow into the engine.

Claim 6

In a combustion engine as defined in claim 1, wherein said regulating circuit means comprises means for timing the lengths of said pulses as a function of airflow into the engine and also as a function of enGine speed.

Claim 7

In a combustion engine as defined in claim 4, wherein said control means comprises means operative when said pulses exceed a predetermined pulse-length to compensate for changes in engine load by changing the functional dependence of said pulses on engine speed.

Claim 8

In a combustion engine as defined in claim 1, wherein said regulating circuit means conprises means for timing the lengths of said pulses as a function of an engine operating condition, and wherein said control means comprises means operative when said pulses exceed a predetermined pulse-length to compensate for changes in engine load by changing the functional dependence of said pulses on said operating condition.

Claim 9

In an engine as defined in claim 8, wherein said monostable multivibrator includes a first voltage divider, and time delay circuit means includes a second voltage divider and switch means for connecting said second voltage divider in parallel with said first voltage divider when said pulses exceed said predetermined pulse length.

Claim 10

In an engine as defined in claim 1, wherein said trigger circuit is a monostable multivibrator.

Claim 11

In an engine as defined in claim 7, wherein said switch means is a first switching transistor of which the emitter-collector path is connected between the tap of said first voltage divider and the tap of said second voltage divider.

Claim 12

In an engine as defined in claim 9, including a resistor connected in series with said emitter-collector path.

Claim 13

In an engine as defined in claim 10, including means for changing the conductive state of said first switching transistor at the beginning of each injection pulse and for a predetermined period that is shorter than the open time of the fuel injection valve at full engine load but longer than said open time at partial load.

Claim 14

In an engine as defined in claim 11, wherein said means is an electronic switch having at least one transistor and at least one RC network.

Claim 15

In an engine as defined in claim 12, further including first and second operating voltages, and wherein the emitter of said transistor of said electronic switch is directly connected to said first operating voltage, said electronic switch further including a resistor connected between the base of said transistor and said first operating voltage; a series-connected resistor and diode connected between said base and said second operating voltage, said diode being connected with such polarity so as to conduct the base current; a resistor connected to said second operating voltage; a capacitor connected between said last-named resistor and the junction between said series-connected resistor and diode; and a diode connected between said capacitor at the junction thereof with said last-named resistor and a point in the control circuit having a voltage at least approximately equal to that of said second operating voltage between successive injection pulses.