FR2694787A1 - A method of regulating the idle speed of an internal combustion engine. - Google Patents

Abstract

Method of regulating the speed of rotation of an internal combustion engine in the idling operating phase, characterized in that it comprises the following steps: - periodically measuring the value of the battery voltage; - deduce therefrom an average value of the battery voltage over a given horizon; - calculate the value of a statistical quantity representative of the difference between each average value of battery voltage and a predetermined threshold value; - Associating with each value of said statistical quantity a corresponding value of the speed of rotation of the engine in idling phase.

Description

METHOD FOR REGULATING THE IDLING REGIME

OF AN INTERNAL COMBUSTION ENGINE.

  The present invention relates to a method of regulating the idle speed of an internal combustion engine equipping in particular a vehicle

automobile.

  A motor vehicle equipped with a spark-ignition or compression-ignition internal combustion engine must be supplied with electrical energy in order to be able to start at any moment and to have a sufficient quantity of power to operate the different electrical receivers of the vehicle. (ignition, lighting, engine cooling fan, etc.) To do this, we classically equip the

  vehicle of an electronic storage battery

  This battery is continuously recharged during engine operation by a powered generator or alternator

by the rotation of the motor shaft.

  The design of the alternator is operated in such a way as to allow the putting into service of the various consumers of currents connected to the battery and this under the critical operating conditions of the engine and in particular at the low speed of rotation of the engine corresponding to

  idle operation of the engine.

  Conventionally, the idling speed of an internal combustion engine of the type fitted to motor vehicles corresponding to the foot-pedal position of the accelerator pedal, evolves little or not in time if it is not with the temperature of the engine. This system is determined for a given type of engine as low as possible so as to meet the consumption and pollution control requirements imposed by the legislation in force. The result is therefore the need to equip motor vehicles powerful alternators capable of producing a high amperage at the low rotational speed corresponding to 1 S engine idle speeds This significant dimensioning of the alternator has many disadvantages: cost, congestion, weight, etc. The method of regulating the rotational speed of the engine in the idle phase makes it possible to eliminate these various disadvantages, in particular by allowing the use of generators of a lower class than those traditionally used, and this at a cost of production. almost

no.

  The method for regulating the rotational speed of an internal combustion engine in the idle phase of operation according to the invention applies to an internal combustion engine comprising a sensor for measuring the value of the voltage of the starter battery. , an engine control system comprising calculation means and information storage means and finally idle speed control means driven by

said engine control system.

  According to the invention, the method of regulating the rotational speed of an engine is characterized in that the rotational speed of the engine in the idle phase of operation is adjusted according to the

value of the battery voltage.

  Thanks to the method that is the subject of the invention, the adaptation of the idling speed makes it possible to maintain electrical equilibrium even with an alternator of weak characteristics. Indeed, when the voltage appears to be too low, particularly because of the putting into service of a powerful electric consumer, idle speed is increased So the alternator is able to produce more electric current and compensate for electricity consumption The raising of the idling speed of the engine allows then to relieve the battery and d avoiding its unloading which operates in a repetitive way causes its destruction The rotation regime is brought back to its nominal value as soon as the

  Battery voltage returns to normal value.

  According to another characteristic of the method for regulating the rotational speed of an internal combustion engine according to the invention, it comprises the following steps: (a) periodically measuring the value of the battery voltage; (b) calculating at each new value of the battery voltage thus measured, the value of a first statistical quantity representative of the average of the values of the battery voltage over a given horizon of measured values; (c) computing for each value so obtained from said first statistical magnitude, the deviation of that value from a predetermined threshold value; (d) calculating the value of a second statistical magnitude representative of the average of the deviations between said first statistical magnitude and said threshold value; (e) associating with each value of said second statistical magnitude a corresponding value of the rotational speed of the motor; (f) controlling the idle speed adjusting means so as to coincide at each instant, the idle rotation speed of said engine with said engine rotation value deduced from

  the value of said second statistical magnitude.

  According to another characteristic of the method of regulating the rotational speed according to the invention, the measurements of the value of the battery voltage and the calculation of the different statistical values are performed after a delay period. According to another characteristic of the method of regulating the rotational speed according to the invention, according to step (e), the associated rotational engine speed values are deduced from a specific mapping contained.

  in the engine control system.

  According to another characteristic of the method of regulating the rotational speed according to the invention, step (b) is suppressed, said first statistical quantity then being

  directly equal to the battery voltage.

  According to another characteristic of the method of regulating the rotational speed according to the invention, step (d) is suppressed, said second statistical quantity then being directly equal to the difference between the first statistical quantity and the threshold value

predetermined.

  The purposes, aspects and advantages of the present invention will be better understood from the

  description given below of a method of

  embodiment of the invention, this embodiment being given by way of non-limiting example, with reference to the appended drawing, in which: FIG. 1 is a schematic view of an internal combustion engine equipped with a implementation of the method according to the invention; FIG. 2 is a functional diagram specifying the various steps of the method according to the invention; FIG. 3 is a graph showing the impact of the battery voltage on the evolution of the idling speed of the engine,

  according to the method according to the invention.

  FIG. 1 therefore describes an internal combustion engine equipped with a device implementing the method of regulating the rotational speed of the engine during the phases of idling operation. Only the elements necessary for the understanding of the invention have been used.

been figured.

  The internal combustion engine shown, for example of the four-stroke type and four-cylinder in line, referenced 1, is equipped with a fuel supply device, for example of the multipoint injection type where each cylinder is supplied with fuel by a specific electro-injector 5. The opening of each electro-injector 5 is controlled by an engine control system 7, which determines the amount of fuel injected

  according to the operating conditions.

  The engine control system 7 also controls the flow of the oxidizing gases, especially in the idle phase of operation via a controlled actuator 4 to control

the opening of the idle bypass.

  This engine control system 7 conventionally comprises a computer comprising a CPU, a random access memory (RAM), a read only memory (ROM), analog-digital converters (A / D), and different input and output interfaces It receives input signals relating to the operation of the motor and the peripheral members, carries out operations and generates output signals intended in particular for

  injectors 5 and actuator means 4.

  Among the input signals f igure the battery voltage information, emitted by a measurement sensor 22 disposed on the line of

  connection of the alternator 12 to the battery 3.

  The engine 1 typically drives an electric generator or alternator 12 capable of producing during the operating ranges of the motor a charging current to the

storage battery 3.

  This alternator 12 essentially comprises a rotor and a stator. The rotor driven by the motor shaft comprises electromagnets constituted by one or more excitation windings. The stator comprises a three-phase winding. The alternating current produced in the three-phase winding. is converted into direct current in a rectifier circuit before

to power the battery 3.

  The implementation of the method that is the subject of the invention is carried out by the engine control system 7, the latter thanks to a strategy implemented in the computer and to tables of values stored in its memories, which control the idle speed by controlling the actuator 4 especially in

  Battery voltage information function.

  According to FIG. 2, the method of regulating the idling speed of the engine as a function of the voltage of the starter battery 3, implemented by the engine control system 7, is as follows. The battery voltage information Vbat measured periodically by the sensor 22 is processed by a first-order low-pass digital filter F1, of the form 1 / (1 + cp), so as to obtain a statistical value V Mbat representative of the average value battery voltage over a given measurement horizon, such as

last measures.

  The filtering formula chosen is then: V Mbat i = V Mbat i-1 + (Vbati (V Mbat i-1)) / FI) with V Mbati value of the statistical magnitude corresponding to the instant Ti (Ti = To + i * P, with the instant of start of the vehicle and the period of measurement of the battery voltage) V Mbati-1 value of the statistical magnitude corresponding to the instant Ti-1; Vbati value of the battery voltage measured at time Ti; F 1 filter constant of the filter Fl;

and V Mbat O = 0.

  The purpose of this first filtering is to take into account an average voltage which does not take into account the short variations of the

  battery voltage, like during a lighthouse call.

  However, in a simplified embodiment of the method that is the subject of the present invention, it is possible to eliminate this filtering and directly process the raw value of the battery voltage Vbati observed at the instant Ti. According to this variant embodiment, then V Mbat i = Vbat i The average value V Mbat having thus been obtained, it is then compared by subtractor means S to a predetermined threshold value Vs corresponding to the normal value of the battery voltage 3 The reference voltage of the starter batteries usually used is equal to 12.7 V. The Ebat gross difference, between V Mbat and Vs, is then processed by new filtering means so as to produce a second statistical value E Mbat representative of the evolution of the difference between the average value of the battery voltage V Mbat and the set voltage Vs on a horizon

given calculated values.

This filtering uses two values of

  separate filtering according to the sign of the difference.

  This decoupling of the treatment according to the positive or negative value of the difference allows a greater flexibility in the dynamic adaptation of the rotational speed in idle phase as a function of

the battery voltage.

  The Ebat gap is therefore first processed by comparator means C which, following the value of the sign of the difference Ebat, positive or negative, send the latter either to the filter F 2 or to the

filter F 3.

  The filtering formula chosen is then: if Ebati> O (again V Mbati> Vs) E Mbat-i = E Mbat i-1 (Ebat_i / F 2) and if Ebati <EO Mbati = E Mbat i-1 (Ebati ) / F 3) with Ebati value of the difference between the first statistical magnitude and the threshold value at time Ti, Ebati = Vmbati Vs; E Mbati value of the second statistical magnitude representative of the mean of the deviations at time Ti; E Mbati-1 value of the second statistical magnitude at time Ti-1; F 2 filtering constant of the filter F 2; F 3 filtering constant of the filter F 3; E Mbat-O = O The use of two constants makes it possible to dissociate the evolution of the values of E Mbat according to the value of the difference Ebat observed One can thus take F 2> F 3 so as to have a faster convergence in case of positive difference than negative difference The reason for this difference in treatment will be specified later in

description.

  Each value E Mbat i of the second statistical magnitude E Mbat is then converted into the rotation speed of the motor Rrali, thanks to the addressing means A which call in a table stored in the memories M of the engine control system 7, the value of rotational speed corresponding to the value of the magnitude

produced.

  FIG. 3 specifies a possible relation between the values of E Mbat and the rotational speed of the motor. The increase of the second statistical magnitude corresponding to a negative variation of the difference between the mean voltage observed and the normal voltage is accompanied by an increase in the speed of rotation from the nominal speed corresponding to the other operating conditions of the motors and to a normal battery voltage up to a maximum value allowed for

  engine idling.

  The development of such a mapping is done by series of measurement at the test bench

for each type of engine.

  The rotational speed value is then directly usable by the engine control system to adjust the idling speed of the engine as soon as the engine returns to the idle operating phase, via the actuator 4 and the

injectors 5.

  In accordance with what has just been described, the operation of the method for regulating the rotational speed of the engine in the phase of

  idle operation is as follows.

  As soon as the engine is started or preferably after a delay period Tbat, the engine control system 7 applies the previously described treatment to the battery voltage information and thus always has the optimum value of the idle speed taking into account

  different electrical consumers present.

  When the battery voltage Vbat decreases due to the commissioning of a powerful electrical consumer, for example commissioning of the air conditioning, the average voltage V Mbat falls consecutively and the difference Ebat with the normal voltage Vs digs the second statistical magnitude E Mbat increases which causes an increase in the idle rotation Rral of the engine Thus the alternator 12 is able to produce more electric current and to compensate the consumption of electricity The raising of the idling speed of the engine allows

thus relieve the battery 3.

  The rise in voltage linked to the increase in the regime causes a decrease in the Ebat gap and therefore a gradual stopping of

  the increase of the rotation regime.

  Stopping the electrical consumers causes a sharp rise in the battery voltage Vbat and therefore the rise in the average voltage V Mbat The difference between the normal voltage and the average voltage then becomes largely positive, which causes a rapid decrease idle rotation speed As previously

  system operation is regulated.

  The use of two different filtering constants for the development of E Mbat according to the sign of the Ebat deviation makes it possible to very rapidly decrease the rotational speed of the motor to reach the nominal operating speed when the demand for electricity has ceased, while the revving can, she,

to proceed more gradually.

  Thus, thanks to the method according to the invention, it is possible to respond to an increase in the electrical consumption of the vehicle without increasing the class of the alternator or discharging

drums.

  Of course, the invention is not limited to the embodiment described and illustrated

  which has only been given as an example.

  On the contrary, the invention includes all the technical equivalents of the means described and their combinations if they are carried out.

following his mind.

  With regard to the implementation of the idle speed regulation method, it can be carried out in various forms: either with analog electronics components for which the summers, comparators and other filters are made with the help of operational amplifiers; either with digital electronics components that would perform the function in hardwired logic; either by a signal processing algorithm implanted in the form of a software module component of an engine control software system operating the microcontroller of a

electronic calculator.

  or else, by a specific chip (custom) whose hardware and software resources have been optimized to perform the functions of the invention microprogrammable chip or not, encapsulated separately or all or part of a coprocessor implanted in all or part a coprocessor implanted in a microcontroller or microprocessor etc. Similarly, the invention includes all technical equivalents applied to an internal combustion engine regardless of its combustion cycle (2 times, 4 times), the fuel used diesel or gasoline or the number of its cylinders.

Claims (1)

  1 1 l A method for regulating the rotational speed of an internal combustion engine in the idle phase of operation, the engine (1) comprising a sensor (22) for measuring the voltage of the starter battery (3), a system engine control unit (7) comprising calculation means and information storage means and idle speed control means (4) controlled by said engine control system (7), characterized in that the engine rotation speed in idle operating phase is adjusted according to the value of the battery voltage.   The method of regulating the rotational speed of an engine according to claim 1, characterized in that it comprises the following steps: (a) periodically measuring the value Vbati of the battery voltage (Vbat); (b) calculating at each new value Vbat i of the battery voltage (Vbat) thus measured, the value V Mbati of a first statistical quantity (V Mbat) representative of the average of the values of the battery voltage over a given horizon of values measured; (c) calculating for each value V Mbat i thus obtained of said first statistical quantity (V Mbat), the difference Ebati of this value at a predetermined threshold value Vs; (d) calculating the value E Mbat i of a second statistical magnitude (E Mbat) representative of the mean of the Ebati deviations between said first statistical magnitude (V Mbat) and said threshold value Vs; (e) associating with each value E Mbat i of said second statistical magnitude (E Mbat) a corresponding value Rrali of the rotational speed of the motor; (f) controlling the adjustment means (4) of the idle speed so as to coincide at each instant, the idle rotation speed of said motor (1) with said value Rrali of engine rotation deduced from the value E Mbati of said   second statistical magnitude (E Mbat).   A method for regulating the rotational speed of an engine according to claim 2, characterized in that the measurements of the value of the battery voltage (3) and the calculation of the statistical values (V Mbat, E Mbat) are operated after a period of timer (Tbat).   l 4 l A method of regulating the rotational speed of an engine according to any one of   Claims 2 to 3, characterized in that   in accordance with step (b) the values of said first statistical magnitude (V Mbat) are calculated from the following formula: V Mbati = V Mbati-1 + ((Vbati (V Mbati-1> / Fl) o Fl is a filtering constant and o V Mbat O = 0.   A method of regulating the rotational speed of an engine according to any one of   Claims 2 to 4, characterized in that * '* * I * 2694787   in accordance with step (d) the values of said statistical magnitude (E Mbat) are calculated from the following formula: if Ebati> O (o Ebat i = V Mbat i Vs) E Mbati = E Mbati-1 (( Ebat_i) / F 2) and if Ebati <OE Mbati = E Mbat_i-1 ((Ebat_i) / F 3)   o F 2 and F 3 are two constants and o E Mbat_ O = 0.   A method of regulating the rotational speed of an engine according to claim 5, characterized   in that F 2 is greater than F 3.   The method of regulating the rotational speed of an engine according to any one of   Claims 2 to 6, characterized in that   in accordance with step (e) the engine rotation speed Rral_i values associated with said E Mbat i values are deduced from a specific map contained in the control system motor (7).   The method for regulating the rotational speed of an engine according to any one of   claims 2 or 3, characterized in that   step (b) is deleted, said first statistical magnitude (V Mbat) then being directly equal to the battery voltage (Vbat).   The method of regulating the rotational speed of an engine according to any one of   Claims 2 to 4, characterized in that the step   (d) is deleted, said second statistical magnitude (E Mbat) then being directly equal to the difference between the first statistical magnitude   (V Mbat) and the predetermined threshold value Vs.