Air-fuel ratio control apparatus for engines

Claim 2

An air-fuel ratio control apparatus for an engine comprising: intake air amount detecting means for detecting an amount of intake air supplied to the engine and providing a signal corresponding to said amount of intake air; intake air amount memorizing means for memorizing the amount of intake air detected by said intake air amount detecting means; throttle opening detecting means for detecting an opening degree of a throttle valve mounted in an intake passage of the engine and providing a signal corresponding to the throttle opening; throttle opening memorizing means for memorizing the throttle opening detected by said throttle opening detecting means; intake air amount determining means for determining a smoothed amount of intake air so as to reflect a predetermined ratio of a former amount of intake air memorized in said intake air amount memorizing means to a current amount of intake air corresponding to an output from said intake air detecting means; throttle opening determining means for determining a smoothed throttle opening so as to reflect a ratio of a former throttle opening memorized in said throttle opening memorizing means to a current throttle opening at said predetermined ratio; air-fuel ratio determining means for the air-fuel ratio of an air-fuel mixture supplied to the engine on the basis of the respective outputs from said intake air amount determining means and said throttle opening determining means; and air-fuel ratio adjusting means for adjusting an air-fuel ratio of the air-fuel mixture supplied to the engine so as to become the air-fuel ratio determined by said air-fuel ratio determining means.

Claim 3

The air-fuel ratio control apparatus according to claim 1, wherein said intake air amount detecting means has a flap portion equipped in said intake passage in such a manner as capable of being displaced by a flow of intake air.

Claim 4

The air-fuel ratio control apparatus according to claim 1, wherein each of said memorizing means is to memorize a value just previous to the one detected by the respective detecting means as the former value; and said intake air amount determining means and said throttle opening determining means are each to set a value obtained by adding said value just previous thereto, memorized by said respective memorizing means, multiplied by n to the newest value and then dividing the resulting product by (n+1).

Claim 5

The air-fuel ratio control apparatus according to claim 1, wherein said air-fuel ratio determining means contains: first target air-fuel ratio determining means for determining a first target air-fuel ratio on the basis of an output from said intake air amount determining means; second target air-fuel ratio determining means for determining a second target air-fuel ratio on the basis of an output from said throttle opening determining means; and final target air-fuel ratio determining means for determining a final target air-fuel ratio on the basis of the respective outputs from said first and second air-fuel ratio determining means.

Claim 6

The air-fuel ratio control apparatus according to claim 4, wherein said first air-fuel ratio determining means comprises memorizing means in which the value determined by said intake air amount determining means is memorized by corresponding to said first air-fuel ratio; and said second air-fuel ratio determining means comprises memorizing means in which the value determined by said throttle opening determining means is memorized by corresponding to said second air-fuel ratio.

Claim 7

The air-fuel ratio control apparatus according to claim 1, wherein said engine is of the fuel injection type.

Claim 8

An air-fuel ratio control apparatus comprising: intake air amount detecting means for detecting an amount of intake air of the engine and providing a signal corresponding to the amount of intake air; intake air amount memorizing means for memorizing the amount of intake air detected by said intake air amount detecting means; throttle opening detecting means for detecting an opening degree of a throttle valve mounted in an intake passage and providing a signal corresponding to the opening degree of the throttle valve; throttle opening memorizing means for memorizing the throttle opening detected by said throttle opening detecting means; intake air amount determining means for determining a smoothed amount of intake air so as to reflect a predetermined ratio of a former amount of intake air memorized in said intake air amount memorizing means to accurent amount of intake air corresponding to an output from said intake air detecting means; throttle opening determining means for determining a smoothed throttle opening so as to reflect a ratio of a former throttle opening memorized in said throttle opening memorizing means to a current throttle opening at said predetermined ratio; a fuel injection valve mounted in said intake passage; basic injection amount determining means for determining a basic fuel injection amount in the basis of an output from said intake air amount detecting means; air-fuel ratio determining means for determining the air-fuel ratio of a air-fuel mixture supplied to the engine on the basis of the respective outputs from said intake air amount determining means and said throttle opening determining means; and final injection amount determining means for determining a final fuel injection amount by correcting the basic fuel injection amount on the basis of the air-fuel ratio determined by said air-fuel ratio determining means in response to the respective outputs from said basic injection amount determining means and said air-fuel ratio determining means.

Claim 9

An air-fuel ratio control apparatus comprising: intake air amount detecting means for detecting an amount of intake air of the engine and providing a signal corresponding to the amount of intake air; intake air amount memorizing means for memorizing the amount of intake air detected by said intake air amount detecting means; throttle opening detecting means for detecting an opening degree of a throttle valve mounted in an intake passage and providing a signal corresponding to the opening degree of the throttle valve; throttle opening memorizing means for memorizing the throttle opening detected by said throttle opening detecting means; intake air amount determining means for determining a smoothed amount of intake air so as to reflect a predetermined ratio of a former amount of intake air memorized in said intake air amount memorizing means to accurent amount of intake air corresponding to an output from said intake air detecting means; throttle opening determining means for determining a smoothed throttle opening so as to reflect a ratio of a former throttle opening memorized in said throttle opening memorizing means to a current throttle opening at said predetermined ratio; a fuel injection valve mounted in said intake passage; basic injection amount determining means for determining a basic fuel injection amount in the basis of an output from said intake air amount detecting means; air-fuel ratio determining means for determining the air-fuel ratio of a air-fuel mixture supplied to the engine on the basis of the respective outputs from said intake air amount determining means and said throttle opening determining means; and final injection amount determining means for determining a final fuel injection amount by correcting the basic fuel injection amount on the basis of the air-fuel ratio determined by said air-fuel ratio determining means in response to the respective outputs from said basic injection amount determining means and said air-fuel ratio determining means.

Claim 10

The air-fuel ratio control apparatus according to claim 7, wherein said fuel injection value is of the electromagnetic type; and each of said basic injection amount determining means and said final injection amount determining means is to determine the pulse width of a driving pulse to be given to said fuel injection valve.

Claim 11

The air-fuel ratio control apparatus according to claim 7, wherein said intake air amount detecting means has a flap portion equipped in said intake passage in such a manner as capable of being displaced by a flow of intake air.

Claim 12

The air-fuel ratio control apparatus according to claim 7, wherein said air-fuel ratio determining means contains; first target air-fuel ratio determining means for determining a first target air-fuel ratio on the basis of an output from said intake air amount determining means; second target air-fuel ratio determining means for determining a second target air-fuel ratio on the basis of an output from said throttle opening determining means; and final target air-fuel ratio determining means for determining a final target air-fuel ratio on the basis of the respective outputs from said first and second air-fuel ratio determining means.

Claim 13

The air-fuel ratio control apparatus according to claim 7, wherein said basic fuel injection amount is set as a value corresponding to the stoichiometoric air-fuel ratio; and said air-fuel ratio determining means is to output a signal representative of a degree of the air-fuel ratio itself.

Claim 14

The air-fuel ratio control apparatus according to claim 11, wherein said final injection amount determining means is to correct the basic fuel injection amount corresponding to the stoichiometric air-fuel ratio by a ratio of the stoichiometric air-fuel ratio to an output value of said air-fuel ratio determining means.