US4140083A — Method and apparatus for lean burn mixture contro…

Claim 1

Independent Claim 266 words

A method for controlling an internal combustion engine to operate with a leaned-out fuel-air mixture, said method including: measuring engine speed; measuring air flow rate into the engine; deriving from these measurements a fuel control signal; correcting said fuel control signal according to engine variables, one of these variables being engine roughness defined as the difference between successive differences of sequential periods of engine revolution; said differences of sequential periods being obtained by counting a first counter upward at a fixed frequency during one engine revolution (period), counting a third counter upward at the same fixed frequency and counting a second counter downward at twice said fixed frequency, transferring the contents of the first counter to the second counter and the contents of the second counter to the third counter at the end of each counting period while setting the first counter to zero, transferring the contents of the third counter to a totalizing register, and counting the totalizing register down at an rpm-dependent frequency, after which the contents of the totalizing register are used to correct said fuel control signal and wherein the improvement comprises the steps of: determining from said contents of said totalizing register if said register had overflowed during the down-counting thereof; determining the algebraic sign of said engine roughness; and choosing one of the four possible combination of states of said overflow and said algebraic sign and providing therefor a first adjustment datum for adjusting said fuel control signal and providing a second adjustment datum for the remaining three of the four possible combinations of states of overflow and algebraic sign.

Claim 2

Independent Claim 266 words

A method for controlling an internal combustion engine to operate with a leaned-out fuel-air mixture, said method including: measuring engine speed; measuring air flow rate into the engine; deriving from these measurements a fuel control signal; correcting said fuel control signal according to engine variables, one of these variables being engine roughness defined as the difference between successive differences of sequential periods of engine revolution; said differences of sequential periods being obtained by counting a first counter upward at a fixed frequency during one engine revolution (period), counting a third counter upward at the same fixed frequency and counting a second counter downward at twice said fixed frequency, transferring the contents of the first counter to the second counter and the contents of the second counter to the third counter at the end of each counting period while setting the first counter to zero, transferring the contents of the third counter to a totalizing register, and counting the totalizing register down at an rpm-dependent frequency, after which the contents of the totalizing register are used to correct said fuel control signal and wherein the improvement comprises the steps of: determining from said contents of said totalizing register if said register had overflowed during the down-counting thereof; determining the algebraic sign of said engine roughness; and choosing one of the four possible combination of states of said overflow and said algebraic sign and providing therefor a first adjustment datum for adjusting said fuel control signal and providing a second adjustment datum for the remaining three of the four possible combinations of states of overflow and algebraic sign.

Claim 3

Dependent Claim 74 words

A method as defined by claim 1 for use with a fuel injection control system in an internal combustion engine, said control system including a control pulse extension circuit (multiplier circuit), said method comprising the further step of: generating first and second voltages to correspond to said first and second adjustment datum, respectively, and applying said first and second voltages alternately to said control pulse extension circuit; whereby a 2-point control process is performed.

Claim 4

Dependent Claim 46 words

A method as defined by claim 1, wherein said algebraic sign of the engine roughness is determined from the most significant bit of said third counter and said condition of overflow of said totalizing register is determined from the most significant bit of said totalizing register.

Claim 5

Dependent Claim 260 words

A fuel mixture controller for an internal combustion engine, said controller including means for measuring air flow and engine speed and forming therefrom fuel control signals and including adjustment means for adjusting said fuel control signals on the basis of engine variables, one of said variables being the engine roughness, defined as the difference between successive differences of sequential periods of engine revolutions, said controller further including first, second and third digital counters and said differences of sequential periods being obtained by counting a first counter upward at a fixed frequency during one engine revolution (period), counting a third counter upward at the said fixed frequency and counting a second counter downward at twice said fixed frequency, transferring the contents of the first counter to the second counter and the contents of the second counter to the third counter at the end of each counting period while setting the first counter to zero, transferring the contents of the third counter to a totalizing register, and counting the totalizing register down at an rpm-dependent frequency, and wherein the improvement comprises: an AND gate one of whose inputs is connected to said third counter to receive the most significant bit thereof at the conclusion of each counting period and the other of whose inputs is connected to said totalizing register to receive the most significant bit thereof at the conclusion of each counting period; and the output of said AND gate is applied to said adjustment means; whereby said fuel control signals are adjusted in the manner of a 2-point control process.

Claim 6

Dependent Claim 260 words

A fuel mixture controller for an internal combustion engine, said controller including means for measuring air flow and engine speed and forming therefrom fuel control signals and including adjustment means for adjusting said fuel control signals on the basis of engine variables, one of said variables being the engine roughness, defined as the difference between successive differences of sequential periods of engine revolutions, said controller further including first, second and third digital counters and said differences of sequential periods being obtained by counting a first counter upward at a fixed frequency during one engine revolution (period), counting a third counter upward at the said fixed frequency and counting a second counter downward at twice said fixed frequency, transferring the contents of the first counter to the second counter and the contents of the second counter to the third counter at the end of each counting period while setting the first counter to zero, transferring the contents of the third counter to a totalizing register, and counting the totalizing register down at an rpm-dependent frequency, and wherein the improvement comprises: an AND gate one of whose inputs is connected to said third counter to receive the most significant bit thereof at the conclusion of each counting period and the other of whose inputs is connected to said totalizing register to receive the most significant bit thereof at the conclusion of each counting period; and the output of said AND gate is applied to said adjustment means; whereby said fuel control signals are adjusted in the manner of a 2-point control process.

Claim 7

Dependent Claim 67 words

A fuel mixture controller as defined by claim 4, wherein said engine is provided with a fuel injection system, including electromagnetic fuel injection valves, said fuel control signals are electric pulses whose width determines the duration of opening of said fuel injection valves, and said adjustment means includes a voltage controlled pulse width extension circuit (multiplier circuit) to which said output from said AND gate is applied.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1982-02-19	1982-08-21	1983-02-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1986-02-19	1986-08-21	1987-02-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1990-02-19	1990-08-21	1991-02-20	$7700.00	Window Closed / Lapsed

Method and apparatus for lean burn mixture control of an internal combustion engine

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