Fuel injection timing control system for an internal-combustion engine, and control method therefor

Claim 2

A fuel injection control system for a fuel injection internal combustion engine comprising: first means for detecting an engine operating condition and producing a first signal for use in determining a fuel injection amount; second means for detecting an engine crank shaft angular position to produce a second signal each time a crank shaft passes a predetermined angular position; third means for operating intake and exhaust valves of the engine in synchronism with the crank shaft rotation so as to operate said intake and exhaust valves with a predetermined valve overlap period during which both of the intake and exhaust valves are open; fourth means for determining said fuel injection amount on the basis of said first signal and producing a control signal for controlling a fuel injection valve, said fourth means determining a timing for delivery of said control signal based on said second signal so as to effect fuel injection in said valve overlap period.

Claim 3

The control system as set forth in claim 1, wherein said fourth means differs the transmission timing of said control signal for each engine cylinder so that said control signal is transmitted during said valve-overlap period of each cylinder.

Claim 4

The control system as set forth in claim 1, wherein said second means is adapted to produce said second signal with a unique signal value in response to said predetermined angular position of said crank shaft of a specific one of the cylinders so as to distinguish the specific cylinder from the remaining cylinders with respect to injection timing.

Claim 5

The control system as set forth in claim 2, wherein said second means is adapted to produce said second signal having a specific signal value for identifying said predetermined angular position of said crank shaft of the specific cylinder.

Claim 6

The control system as set forth in claim 1, wherein said first signal is indicative-of engine load and said fourth means is responsive to said first signal to advance the transmission timing of said control signal to outside of said valve-overlap period when engine load exceeds a predetermined threshold and, otherwise, to maintain the transmission timing within said valve-overlap period.

Claim 7

The control system as set forth in claim 2, wherein said fourth means is responsive to said first signal indicative of relatively high load condition on the engine to advance the delivery timing of said control .signal to outside of said valve overlapping period and, otherwise, to maintain the delivery timing within said valve overlapping period.

Claim 8

The control system as set forth in claim 6, wherein said fourth means advances the transmission timing of said control signal to a crank shaft angular position corresponding to the combustion stroke in the engine cylinder when engine load exceeds the predetermined threshold.

Claim 9

The control system as set forth in claim 6, wherein said fourth means advances the control signal delivery timing at a crank shaft angular position corresponding to compression stroke in the engine cylinder.

Claim 10

A fuel injection timing control system for an internal combustion engine comprising: a fuel injection valve provided adjacent an intake port of each engine cylinder; a first detector for producing, a first signal indicative of a fuel injection control parameter for determining a fuel injection amount; second detector for producing a crank reference signal every time a crank shaft rotates across a predetermined crank reference angle; third means for operating an intake valve and exhaust valve in synchronism with an engine revolution, said third means providing a predetermined period of valve overlap in opening of said intake and exhaust valves; fourth means for determining a fuel injection amount to produce a fuel injection pulse indicative of a duty cycle of said fuel injection valve corresponding to the determined fuel injection amount, said fourth means delivering said fuel injection pulse at a given timing in which at lease some'of fuel injection pulse is delivered to said fuel injection valve within said valve overlap period.

Claim 11

A fuel injection timing control system for an internal combustion engine comprising: a fuel injection valve provided adjacent an intake port of each engine cylinder; a first detector for producing, a first signal indicative of a fuel injection control parameter for determining a fuel injection amount; second detector for producing a crank reference signal every time a crank shaft rotates across a predetermined crank reference angle; third means for operating an intake valve and exhaust valve in synchronism with an engine revolution, said third means providing a predetermined period of valve overlap in opening of said intake and exhaust valves; fourth means for determining a fuel injection amount to produce a fuel injection pulse indicative of a duty cycle of said fuel injection valve corresponding to the determined fuel injection amount, said fourth means delivering said fuel injection pulse at a given timing in which at lease some'of fuel injection pulse is delivered to said fuel injection valve within said valve overlap period.

Claim 12

The control system as set forth in claim 9, which further comprises a fifth detector for producing a load signal representative of the load condition on the engine, and said fourth means sets said fuel injection timing so that at least part of said fuel injection pulse train is delivered to said fuel injection valve when said engine load signal value is below a given threshold.

Claim 13

The control system as set forth in claim 10, which further comprises means for preheating an intake air during said intake air flowing in an air induction passage of the engine.

Claim 14

The control system as set forth in claim 11, wherein said preheating mans is an engine coolant passage formed in an intake manifold of said induction passage for .flowing a heating engine coolant therethrough.

Claim 15

The control system as set forth in claim 11, wherein said preheating means is a heater unit inserted into said induction passage.

Claim 16

The control system as set forth in claim 13, wherein said induction passage is separated into primary passage and secondary passage and, said heater unit is inserted in said primary passage, which primary and secondary passages are respectively provided primary and secondary throttle valves and said secondary throttle valve is closed during relatively low load condition on the engine.

Claim 17

The control system as set forth in claim 10, wherein said fourth means delivers said fuel injection pulse train at a timing across the beginning of said valve overlap period.

Claim 20

The method as set forth in claim 16, wherein said control signal transmission timing is different for each cylinder so that said control signal is output to each fuel injection valve during said valve-overlap period of the corresponding cylinder.

Claim 21

The method as set forth in claim 17, wherein said control signal transmission timing is advanced when load on the engine exceeds a predetermined level.

Claim 23

The method as set forth in claim 18, wherein said .transmission timing is advanced into the combustion stroke of the engine cylinder when the engine load exceeds said predetermined level.

Claim 24

The method as set forth in claim 18, wherein said transmission timing is advanced to after the bottom dead center of the suction stroke when engine load exceeds said predetermined level.

Claim 25

The method as set forth in claim 17, wherein the compression top dead center of a specific one of the cylinders is detected in the step of detecting crank shaft angular position in order to facilitate correct transmission timing for each of the engine cylinders.

Claim 28

The method of claim 23, further comprising the steps of: a) sensing engine load; and b) advancing the time of fuel injection out of said valve-overlap period when engine load exceeds a predetermined level.