A/D Conversion period control for internal combustion engines

Claim 2

In a method of controlling operation of internal combustion engine having an arrangement for analog-to-digital converting at least one analog type pulsating control variable indicative of engine operation including at least one of intake air pressure and intake air quantity, said method comprising the steps of: detecting a cycle to cycle period of pulsation of the control variable; determining a conversion interval for the analog-to-digital converting corresponding to the detected cycle to cycle period of pulsation and controlling analog-to-digital conversion in accordance with the determined conversion interval; sampling the analog type pulsating control variable during a first cycle and during a second cycle immediately following the first cycle and analog-to-digital converting the samples in accordance with the determined conversion interval; determining a difference between converted digital values of the first and second cycles; updating the conversion interval previously determined so as to reduce the detected difference to update a next cycle conversion timing; and sampling the control variable during a third cycle and analog-to-digital converting the third cycle sample in accordance with the updated conversion interval.

Claim 3

A method according to claim 1, wherein said engine is a four-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU3## where m represents the number of cylinders, N represents the engine speed (rpm) and n represents a given positive integer.

Claim 4

A method according to claim 1, wherein said engine is a four-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU4## where m represents the number of cylinders and n represents a given positive integer.

Claim 5

A method according to claim 1, wherein said engine is a two-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU5## where m represents the number of cylinders, N represents the engine speed (rpm) and n represents a given positive integer.

Claim 6

A method according to claim 1, wherein said engine is a two-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU6## where m represents the number of cylinders and n represents a given positive integer.

Claim 7

A method according to claim 2, 3, 4 or 5, wherein the next A/D conversion interval is determined as a function of only the difference between two successive analog-to-digital converted values of said control variable.

Claim 8

A method according to claim 2 or 4, wherein the updated analog-to-digital conversion interval is determined as a function of the difference between two successive analog-to-digital converted values of said control variable and the speed of said engine.

Claim 9

In an arrangement for controlling the operation of an internal combustion engine which includes a system for analog-to-digital converting at least one analog type pulsating control variable indicative of engine operation including at least one of intake air pressure and intake air quantity, said arrangement comprising: means for detecting a cycle to cycle period of pulsation of the control variable; means for determining a conversion interval for analog-to-digital converting corresponding to the detected cycle to cycle period of pulsation and controlling analog-to-digital conversion in accordance with the determined conversion interval; means for sampling the analog type pulsating control variable during a first cycle and during a second cycle immediately following the first cycle and analog-to-digital converting the samples in accordance with the determined conversion interval; means for determining a difference between converted digital values of the first and second cycles; means for updating the conversion interval previously determined so as to reduce the detected difference to update a next cycle conversion timing; and means for sampling the control variable during a third cycle and analog-to-digital converting the third cycle sample in accordance with the updated conversion interval.

Claim 10

In an arrangement for controlling the operation of an internal combustion engine which includes a system for analog-to-digital converting at least one analog type pulsating control variable indicative of engine operation including at least one of intake air pressure and intake air quantity, said arrangement comprising: means for detecting a cycle to cycle period of pulsation of the control variable; means for determining a conversion interval for analog-to-digital converting corresponding to the detected cycle to cycle period of pulsation and controlling analog-to-digital conversion in accordance with the determined conversion interval; means for sampling the analog type pulsating control variable during a first cycle and during a second cycle immediately following the first cycle and analog-to-digital converting the samples in accordance with the determined conversion interval; means for determining a difference between converted digital values of the first and second cycles; means for updating the conversion interval previously determined so as to reduce the detected difference to update a next cycle conversion timing; and means for sampling the control variable during a third cycle and analog-to-digital converting the third cycle sample in accordance with the updated conversion interval.

Claim 11

An arrangement according to claim 8, wherein said engine is a four-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU7## where m represents the number of cylinders, N represents the engine speed (rpm) and n represents a given positive integer.

Claim 12

An arrangement according to claim 8, wherein said engine is a four-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU8## where m represents the number of cylinders and n represents a given positive integer.

Claim 13

An arrangement according to claim 8, wherein said engine is a two-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU9## where m represents the number of cylinders, N represents the engine speed (rpm) and n represents a given positive integer.

Claim 14

An arrangement according to claim 8, wherein said engine is a two-cycle engine, and wherein said analog-to-digital conversion interval is determined by the following expression ##EQU10## where m represents the number of cylinders and n represents a given positive integer.

Claim 15

An arrangement according to claim 9, 10, 11 or 12, wherein the next A/D conversion interval is determined as a function of only the difference between two successive analog-to-digital converted values of said control variable.

Claim 16

An arrangement according to claim 9 or 11, wherein the updated analog-to-digital conversion interval is determined as a function of the difference between two successive analog-to-digital converted values of said control variable and the speed of said engine.