Process and device for controlling the idling speed of a heat engine

Claim 1

A process for controlling the idling speed of a heat engine with controlled ignition by modification of air flow admitted to an intake mainfold of the engine when predetermined idling conditions are detected, said modification of air flow being performed by a double-action actuator that causes a passage section of a bypass to vary in parallel with a gas butterfly or a position of an idling stop of said butterfly, wherein a control signal for controlling the actuator according to an instruction value is processed by a microprocessor receiving signals associated with pedetermined input parameters, including a signal indicative of a primary current for ignition, and wherein for each ignition pulse provided by the interruption of the primary current the process comprises: (a) counting clock signals by means of a counter, storing the contents of the counter in a period memory, after the contents of the period memory have been transferred into a preceding period memory, and then resetting the clock signals counter to zero; (b) determining an instruction period from a table of values, as a function of said predetermined input parameters, including the temperature of the cooling water of the engine; (c) determining a deviation between the stored period and the instruction period; (d) determining a threshold from a table of values, as a function of the deviation; (e) determining a slope as a difference between the period and the preceding period; (f) determining a maximum slope, if the deviation is negative and at least if the slope is positive, also as a function of the deviation; (g) if the deviation is positive or zero, or if the slope is negative or zero, or further if the slope is less than or equal to said maximum slope, determining a weighted slope produced from the slope by a number (N) of predetermined weight, computing the new value of a sum by adding the deviation and the weighted slope algebraically to the preceding value of this sum, and comparing the absolute value of this new value with the threshold; (h) determining a remainder, if said absolute value is greater than or equal to the threshold, as a difference between the sum and the threshold; and (i) determining, as a function of predetermined comparisions between the above-determined values, whether or not said control signal, which represents a predetermined basic corrective action, should be sent to the actuator and in what direction, before memorizing the remainder as the sum to recommence a new cycle while awaiting a new ignition interruption.

Claim 6

A device for controlling the idling speed of a heat engine with controlled ignition by modification of air flow admitted to an intake maninfold of the engine when predetermined idling conditions are detected, said modification of air flow being performed by an actuator, wherein a control signal for controlling the actuator according to an instruction value is processed by a microprocessor receiving signals associated with predetermined input parameters, including a signal indicative of a primary current for ignition, comprising: sensors for producing detection signals indicative of said predetermined input parameters and for applying said detection signal to said microprocessor; wherein for each ignition pulse provided by the interruption of the primary current said microprocessor performs the following processing functions, counting clock signals by means of a counter, storing the contents of the counter in a period memory, after the contents of the period memory have been transferred into a preceding period memory, and then resetting the clock signals counter to zero, determining an instruction period from a table of values, as a function of said predetermined input parameters, including the temperature of the cooling water of the engine, determining a deviation between the stored period and the instruction period, determining a threshold from a table of values, as a function of the deviation, determining a slope as a difference between the period and the preceding period, determining a maximum slope, if the deviation is negative and at least if the slope is positive, also as a function of the deviation, if the deviation is positive or zero, or if the slope is negative or zero, or further if the slope is less than or equal to said maximum slope, determining a weighted slope produced from the slope by a number (N) of predetermined weight, computing the new value of a sum by adding the deviation and the weighted slope algebraically to the preceding value of this sum, and comparing the absolute value of this new value with the threshold, determining a remainder, if said absolute value is greater than or equal to the threshold, as a difference between the sum and the threshold and determining, as a function of predetermined comparisons between the above-determined values, whether or not said control signal, which represents a predetermined basic corrective action, should be sent to the actuator and in what direction, before memorizing the remainder as the sum to recommence a new cycle while awaiting a new ignition interruption; and said actuator comprising a double-action actuator controlled by said control signal for varying a passage section of a bypass in parallel with a gas butterfly or a position of an idling stop of said butterfly.

Claim 7

A device for controlling the idling speed of a heat engine with controlled ignition by modification of air flow admitted to an intake maninfold of the engine when predetermined idling conditions are detected, said modification of air flow being performed by an actuator, wherein a control signal for controlling the actuator according to an instruction value is processed by a microprocessor receiving signals associated with predetermined input parameters, including a signal indicative of a primary current for ignition, comprising: sensors for producing detection signals indicative of said predetermined input parameters and for applying said detection signal to said microprocessor; wherein for each ignition pulse provided by the interruption of the primary current said microprocessor performs the following processing functions, counting clock signals by means of a counter, storing the contents of the counter in a period memory, after the contents of the period memory have been transferred into a preceding period memory, and then resetting the clock signals counter to zero, determining an instruction period from a table of values, as a function of said predetermined input parameters, including the temperature of the cooling water of the engine, determining a deviation between the stored period and the instruction period, determining a threshold from a table of values, as a function of the deviation, determining a slope as a difference between the period and the preceding period, determining a maximum slope, if the deviation is negative and at least if the slope is positive, also as a function of the deviation, if the deviation is positive or zero, or if the slope is negative or zero, or further if the slope is less than or equal to said maximum slope, determining a weighted slope produced from the slope by a number (N) of predetermined weight, computing the new value of a sum by adding the deviation and the weighted slope algebraically to the preceding value of this sum, and comparing the absolute value of this new value with the threshold, determining a remainder, if said absolute value is greater than or equal to the threshold, as a difference between the sum and the threshold and determining, as a function of predetermined comparisons between the above-determined values, whether or not said control signal, which represents a predetermined basic corrective action, should be sent to the actuator and in what direction, before memorizing the remainder as the sum to recommence a new cycle while awaiting a new ignition interruption; and said actuator comprising a double-action actuator controlled by said control signal for varying a passage section of a bypass in parallel with a gas butterfly or a position of an idling stop of said butterfly.