EP2480776B1 - Prediction of engine rotation speed during the end of rotation and application of the prediction for an estimation of crankcase stop position - Google Patents

Description

Technical field of the invention

The present invention claims the priority of the French application 0956536 filed on September 23, 2009 whose content (text, drawings and claims) is hereby incorporated by reference.

The present invention relates to the field of internal combustion engines, and more particularly to the anticipated determination of the rotational speed in the stopping phase of the engine.

Technological background

In order to know and follow the position of each of the cylinders in a cycle, the electronic computers mainly have information provided by two sensors, which respectively characterize the rotation of the crankshaft of the engine (this is called a speed sensor), and potentially the rotation of at least one camshaft (this is called a position sensor AAC or camshaft).

During a cycle of a 4-stroke engine, the crankshaft performs 2 turns, a rotation of 720 °. For the sake of clarity, in accordance with the usual practice, we ask that a cycle starts at 0 ° crankshaft angle at the beginning of a compression phase of a given cylinder and ends at 720 ° at the end of the intake phase of this same cylinder.

The flywheel, secured to the crankshaft of the engine, is provided on its periphery with a set of teeth, called target, opposite which is positioned the speed sensor. It delivers an alternating voltage in crenels, presenting rising electric fronts and descending electric fronts, and whose frequency varies with the engine speed. Typically, the flywheel may have, for example, 58 teeth and two gaps (that is to say, a toothing of 60 teeth including 2 missing). The sensor will detect these gaps thus providing information on the position of the crankshaft and the speed of rotation or engine speed.

It is known to determine the instantaneous engine speed from the measurement of an inter-tooth duration, in other words, the time separating two rising fronts or two descending fronts. The knowledge of the engine speed can be used advantageously in various controls or engine commands such as improving the restart of the engine internal combustion engine for example to control the stopping cylinder, in particular in motor vehicles equipped with an automatic on / off.

However, the control or control in question can obviously not be implemented without knowledge of the engine speed, which can be troublesome to respond to problems of motor vehicles equipped with an automatic on / off using a starter.

• On détermine et on enregistre le régime de rotation réel du vilebrequin à des positions angulaires dudit vilebrequin pour une plage de positions angulaires du vilebrequin délimitée par une première position angulaire et une seconde position angulaire correspondant à des oscillations périodiques angulairement de diminution de la vitesse de rotation du vilebrequin.
• On détermine une constante en fonction de l'écart des carrés des régimes réels déterminé pour les première et seconde positions angulaires,
• On détermine un régime prédit de rotation du vilebrequin pour une troisième position angulaire du vilebrequin, non comprise dans la plage de positions angulaires du vilebrequin, en fonction de la constante et du régime réel déterminé à une quatrième position angulaire comprise dans ladite plage et telle que l'écart entre les troisième et quatrième positions angulaires est égal à ladite plage ou est un multiple de celle-ci.

The invention aims to solve one or more of these disadvantages. The invention thus relates to a method for predicting the rotational speed of an internal combustion engine crankshaft in an end-of-rotation phase, characterized in that:

• The actual rotational speed of the crankshaft is determined and recorded at angular positions of said crankshaft for a range of angular positions of the crankshaft delimited by a first angular position and a second angular position corresponding to angular periodic oscillations of decrease in the speed of rotation. crankshaft.
• A constant is determined as a function of the squared deviation of the actual regimes determined for the first and second angular positions,
• A predicted crankshaft rotation speed is determined for a third angular position of the crankshaft, not within the range of angular positions of the crankshaft, as a function of the constant and the actual speed determined at a fourth angular position in said range and such that the difference between the third and fourth angular positions is equal to or is a multiple of said range.

The actual speed measurement measured over a given range of angular position is thus used to predict at a future angular position of the crankshaft.

• De préférence, la seconde position angulaire correspond à la position à l'instant présent du vilebrequin qui est la dernière position angulaire pour laquelle on puisse déterminer un régime réel.
• Dans une variante où le moteur comprend quatre cylindres, la plage de positions angulaires du vilebrequin est avantageusement de 180°, 360° ou 720° ce qui correspond respectivement à une phase moteur, un tour moteur, un cycle moteur. La plage est représentative de la périodicité des couples de perte des phases d'admission, compression, détente et échappement du moteur et du déphasage des cylindres. De préférence la plage de positions angulaires du vilebrequin est de 360° pour avoir une meilleure précision de prédiction du régime.

• Dans une variante où le moteur comprend trois cylindres, la plage est de 240° ou de 720 °, en raison du déphasage des cylindres
• Dans une variante où le moteur comprend six cylindres, la plage est de 120°, 240° ou de 720 °, en raison du déphasage des cylindres.
• le vilebrequin étant solidaire en rotation d'une roue dentée comprenant des dents servant à déterminer la position angulaire dudit vilebrequin, la largeur angulaire entre chaque dent étant de 6°, le régime prédit de rotation du vilebrequin pour la troisième position angulaire du vilebrequin est déterminé en fonction du régime réel en appliquant la relation suivante : $${\tilde{\mathrm{N}}}_{\mathrm{n}+\mathrm{d}}=\sqrt{{\mathrm{N}}_{\mathrm{n}-\frac{\mathrm{T}}{\mathrm{6}}+\mathrm{B}}^{\mathrm{2}}-\left(\mathrm{A}+\mathrm{1}\right)\cdot {\mathrm{C}}_{\mathrm{0}}}$$
  
  dans laquelle :
  • A et B sont des variables telles que : $$\mathrm{A}=\mathrm{INT}\left(\frac{\mathrm{6}\mathrm{d}}{\mathrm{T}}\right)\mathrm{et\; B}=\mathrm{d}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}\cdot \mathrm{A}$$
    
  • n est l'indice de la dent repérant la seconde position angulaire du vilebrequin,
  • n+d est l'indice de la dent repérant la troisième position angulaire du vilebrequin,
  • $\mathrm{n}-\frac{\mathrm{T}}{\mathrm{6}}+\mathrm{B}$
    
    est l'indice de la dent repérant la quatrième position angulaire du vilebrequin,
  • et INT est la fonction fraction entière.

In addition, the invention may include one or more of the following features:

• Preferably, the second angular position corresponds to the position at the present moment of the crankshaft, which is the last angular position for which a real regime can be determined.
• In a variant where the engine comprises four cylinders, the range of angular positions of the crankshaft is advantageously 180 °, 360 ° or 720 ° which corresponds to respectively to a motor phase, a motor revolution, a motor cycle. The range is representative of the periodicity of the loss couples of the phases of admission, compression, expansion and exhaust of the engine and the phase shift of the cylinders. Preferably the range of angular positions of the crankshaft is 360 ° to have a better precision of the prediction of the regime.

• In a variant where the engine comprises three cylinders, the range is 240 ° or 720 °, because of the phase shift of the cylinders
• In a variant where the engine comprises six cylinders, the range is 120 °, 240 ° or 720 °, due to the phase shift of the cylinders.
• the crankshaft being integral in rotation with a toothed wheel comprising teeth for determining the angular position of said crankshaft, the angular width between each tooth being 6 °, the predicted crankshaft rotation speed for the third angular position of the crankshaft is determined according to the actual regime by applying the following relation: $${\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{d}}=\sqrt{{\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{B}}^{\mathrm{2}}-\left(\mathrm{AT}+\mathrm{1}\right)\cdot {\mathrm{VS}}_{\mathrm{0}}}$$
  
  in which :
  • A and B are variables such as: $$\mathrm{AT}=\mathrm{INT}\left(\frac{\mathrm{6}\mathrm{d}}{\mathrm{T}}\right)\mathrm{and\; B}=\mathrm{d}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}\cdot \mathrm{AT}$$
    
  • n is the index of the tooth locating the second angular position of the crankshaft,
  • n + d is the index of the tooth locating the third angular position of the crankshaft,
  • $\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{B}$
    
    is the index of the tooth identifying the fourth angular position of the crankshaft,
  • and INT is the whole fraction function.

• Le procédé comprend en outre les étapes suivantes :
  • on détermine le régime prédit à la dent d'indice n+1,
  • on calcule, à partir du régime prédit à la dent d'indice n+1, un temps inter-dents,
  • on incrémente un compteur de temps du temps inter-dents calculé,
  • on réitère les précédentes étapes sur les dents d'indices suivants tant que la valeur du compteur de temps est inférieure à un temps fixé,
  • on détermine un régime prédit pour le temps fixé, par interpolation entre les régimes prédits pour les deux derniers indices.

There is thus a general formulation in the case of a conventional toothed wheel of 58 teeth and two gaps, that is to say, a toothing of 60 teeth, 2 missing, or a tooth to identify 6 ° rotation of the crankshaft.

• The method further comprises the steps of:
  • the predicted diet is determined for the tooth of index n + 1,
  • from the predicted diet at the tooth of index n + 1, an inter-tooth time is calculated,
  • incrementing a time counter of the calculated inter-tooth time,
  • the preceding steps are reiterated on the teeth of subsequent indices as long as the value of the time counter is less than a set time,
  • a predicted regime is determined for the fixed time, by interpolation between the predicted regimes for the last two indices.

This makes it possible to know in advance the regime to come after a determined time and can make it possible to anticipate actions of motor control.

Furthermore, the invention also relates to an application of the method of the invention to the prediction of the stopping cylinder of an internal combustion engine, characterized in that the third angular position of the crankshaft corresponds to a top dead center. combustion. The estimation of the speed for angular positions of the crankshaft corresponding to a top dead center, also called PMH combustion, makes it possible to determine the last PMH for which the estimated speed will be non-zero and to deduce the cylinder in corresponding compression that is designated as the stop cylinder.

Brief description of the drawings

• La figure 1 est une représentation schématique un moteur à combustion interne 1.
• La figure 2 est un diagramme montrant la phase de fin de rotation du vilebrequin.
• La figure 3 illustre la procédure de prédiction du régime moteur sur un angle fixé.
• La figure 4 illustre la procédure de prédiction du régime moteur sur un temps fixé.
• La figure 5 illustre la procédure de prédiction du cylindre d'arrêt.

Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, with reference to the figures in which:

• The figure 1 is a schematic representation of an internal combustion engine 1.
• The figure 2 is a diagram showing the end of rotation phase of the crankshaft.
• The figure 3 illustrates the procedure of predicting the engine speed at a fixed angle.
• The figure 4 illustrates the procedure of predicting the engine speed over a fixed time.
• The figure 5 illustrates the procedure for predicting the stop cylinder.

detailed description

The figure 1 shows schematically an internal combustion engine 1 comprising a crankshaft 2. The internal combustion engine is equipped with a device 3 for determining the rotational position of the crankshaft 2. This device comprises a toothed wheel 4, a speed sensor 5 connected to an electronic control unit 6 also called ECU. The toothed wheel 4 is integrally connected in rotation to the crankshaft 2 so that when the internal combustion engine 1 operates, the toothed wheel 4 rotates relative to the 1. The periphery of the toothed wheel 4 has teeth 7 corresponding to an angular width of 3 ° and two teeth are separated by a recess 8 with an angular width of 3 °. In one part of the periphery, two adjacent teeth 7 have been removed to have an enlarged tooth gap called spacing 9. At each passage between a tooth 7 and a recess 8 or at the spacing 9, there is a tooth flank 10 The ECU 6 comprises the calculation and storage means necessary for determining the actual engine speed and the predicted engine speed according to the invention.

We define as the inter-tooth duration, t _id , the time separating two successive identical fronts. The fronts can be 12 or downs 13. A so-called instantaneous or real N regime expressed in degree / second can then be estimated by the following relation: $$\mathrm{NOT}=\frac{\mathrm{6}}{{\mathrm{t}}_{\mathrm{id}}}$$

The sensor 5 is a Hall effect sensor mounted in a fixed manner with respect to the internal combustion engine 1. The sensor 5 captures the succession of teeth 7 and tooth gaps 8 or the spacing 9 which passes in front of it and generates a crenelated electrical signal 11, having rising electric edges 12 and descending electrical fronts 13, the frequency of which varies with the engine rotation speed N.

According to the invention, during an end-of-rotation phase of the crankshaft of an internal combustion engine, the engine speed can be predicted using information based on the difference between a current instantaneous squared regime and the engine speeds. snapshot prior to squared. The term "end of rotation phase" is understood to mean the period following a stopping of the operation of the internal combustion engine 1 due to a cut by the ECU 6 of the injection and ignition.

The figure 2 shows the phase of end of rotation of the crankshaft 2 of the internal combustion engine 1 in the form of a diagram giving the variation of the speed N as a function of the angle θ of the crankshaft 2. The figure 2 shows that during the final rotation phase the rotation speed N of the crankshaft 2 decreases. Indeed, the internal combustion engine 1 does not provide energy and loss of torque due to the friction forces, but not only, oppose the rotation of the crankshaft 2 of the engine 1 and slow the speed of rotation N crankshaft 2. The figure 2 further shows that the decrease in the rotation speed N of the crankshaft is not monotonous but presents oscillations periodically angularly, in other words on a range T of angular positions. Indeed, these oscillations are due to the fact that certain loss pairs such as those generated by the efforts of admission, compression, expansion and exhaust which are periodic phase shift between the engine cycles of each cylinder of the engine.

• Le principe fondamental de la dynamique appliquée aux rotations nous donne : $$\mathrm{J}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">d</figure-callout>}}^{\mathrm{2}}\mathrm{<figure-callout\; id="2"\; label="\theta \; t\; dt"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\theta </figure-callout>}\left(\mathrm{t}\right)}{{\mathrm{dt}}^{}}=\sum \mathrm{C}\left(\mathrm{\theta }\left(\mathrm{t}\right)\right)$$
  

The invention will be better understood following the following demonstration:

• The fundamental principle of the dynamics applied to rotations gives us: $$\mathrm{J}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">d</figure-callout>}}^{\mathrm{2}}\mathrm{<figure-callout\; id="2"\; label="\theta \; t\; dt"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\theta \; </figure-callout>}\left(\mathrm{t}\right)}{{\mathrm{dt}}^{}}=\Sigma \mathrm{VS}\left(\mathrm{\theta }\left(\mathrm{t}\right)\right)$$
  

• J : le moment d'inertie des éléments du moteur reliés à la roue dentée 4,
• θ(t) l'angle du vilebrequin 2 en fonction du temps,
• ∑C(θ(t)) : en phase de fin de rotation moteur, la somme des couples de perte responsables de l'arrêt en rotation du moteur.

With:

• J: the moment of inertia of the motor elements connected to the toothed wheel 4,
• θ (t) the angle of the crankshaft 2 as a function of time,
• ΣC (θ (t)): in phase of end of motor rotation, the sum of the loss couples responsible for the stopping of rotation of the motor.

, il vient : $$\mathrm{J}\cdot \frac{\mathrm{d\theta }\left(\mathrm{t}\right)}{\mathrm{dt}}\cdot \frac{{\mathrm{d}}^{\mathrm{2}}\mathrm{\theta }\left(\mathrm{t}\right)}{{\mathrm{dt}}^{\mathrm{2}}}=\sum \frac{\mathrm{d\theta }\left(\mathrm{t}\right)}{\mathrm{dt}}\cdot \mathrm{C}\left(\mathrm{\theta }\left(\mathrm{t}\right)\right)$$

Multiplying each term of the relation (2) by the regime N also determined by the following relation: $$\mathrm{NOT}=\frac{\mathrm{d\theta }\left(\mathrm{t}\right)}{\mathrm{dt}}$$

, he comes : $$\mathrm{J}\cdot \frac{\mathrm{d\theta }\left(\mathrm{t}\right)}{\mathrm{dt}}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">d</figure-callout>}}^{\mathrm{2}}\mathrm{<figure-callout\; id="2"\; label="\theta \; t\; dt"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\theta \; </figure-callout>}\left(\mathrm{t}\right)}{{\mathrm{dt}}^{}}=\Sigma \frac{\mathrm{d\theta }\left(\mathrm{t}\right)}{\mathrm{dt}}\cdot \mathrm{VS}\left(\mathrm{\theta }\left(\mathrm{t}\right)\right)$$

By integrating the relation (4) between a first instant t ₁ and a second instant t ₂ , with θ ₁ the crank angle taken at time t ₁ , such that: $$\mathrm{\theta }\left({\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)={\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_{\mathrm{1}}$$

And θ ₂ , the crankshaft angle raised to a second instant t ₂ , such that: $${\mathrm{\theta }\left({\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{2}}\right)=\mathrm{<figure-callout\; id="2"\; label="\theta "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_{\mathrm{2}}$$

He comes then: $$\frac{\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">J</figure-callout>}}{\mathrm{2}}\cdot {\left[{\left(\frac{\mathrm{d\theta }\left(\mathrm{t}\right)}{\mathrm{dt}}\right)}^{\mathrm{2}}\right]}_{{\mathrm{t}}_{\mathrm{1}}}^{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{2}}}={\left[\int \mathrm{VS}\left(\mathrm{\theta }\left(\mathrm{t}\right)\right)\right]}_{{\mathrm{t}}_{\mathrm{1}}}^{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{2}}}$$

Or : $$\frac{\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">J</figure-callout>}}{\mathrm{2}}\cdot {\left[{\left(\frac{\mathrm{<figure-callout\; id="2"\; label="d\theta \; dt"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">d\theta \; </figure-callout>}}{\mathrm{dt}}\right)}^{\mathrm{2}}\right]}_{{\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_{\mathrm{1}}}^{{\mathrm{<figure-callout\; id="2"\; label="\theta "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_{\mathrm{2}}}={\left[\int \mathrm{VS}\left(\mathrm{\theta }\right)\right]}_{{\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_{\mathrm{1}}}^{{\mathrm{<figure-callout\; id="2"\; label="\theta "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_{\mathrm{2}}}$$

Either, using the relation (3): $${\mathrm{NOT}}_{{\mathrm{\theta }}_{\mathrm{2}}}^{\mathrm{2}}-{\mathrm{<figure-callout\; id="1"\; label="NOT\; \theta "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">NOT\; </figure-callout>}}_{{\mathrm{\theta }}_{}}^{{\mathrm{}}_{\mathrm{1}}}=\frac{\mathrm{2}}{\mathrm{J}}\cdot \left(\int \mathrm{VS}\left({\mathrm{\theta }}_{\mathrm{2}}\right)-\int \mathrm{<figure-callout\; id="1"\; label="VS\; \theta "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">VS\; </figure-callout>}\left({\mathrm{\theta }}_{}\right)\left({\mathrm{}}_{\mathrm{1}}\right)\right)$$

It is then noted judiciously that the relation (9) is particularly advantageous when the difference between θ ₁ and θ ₂ corresponds to a range T of angular positions.

Thus, preferably, for an engine comprising four cylinders, the range T of angular positions of the crankshaft 2 is 180 °, 360 ° or 720 °.

More preferably, the range T is 360 °, to have a better precision of the prediction of the regime.

Thus, because of the angular periodicity of the pairs of losses, the second term of the relation (9) is advantageously a constant C ₀ and can therefore be written: $$\left|{\mathrm{NOT}}_{{\mathrm{\theta }}_{\mathrm{1}}+\mathrm{T}}^{\mathrm{2}}-{\mathrm{<figure-callout\; id="1"\; label="NOT\; \theta "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">NOT\; </figure-callout>}}_{{\mathrm{\theta }}_{}}^{{\mathrm{}}_{\mathrm{1}}}\right|={\mathrm{NOT}}_{{\mathrm{\theta }}_{\mathrm{2}}-\mathrm{T}}^{\mathrm{2}}-{\mathrm{<figure-callout\; id="2"\; label="NOT\; \theta "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">NOT\; </figure-callout>}}_{{\mathrm{\theta }}_{}}^{{\mathrm{}}_{\mathrm{2}}}={\mathrm{VS}}_{\mathrm{0}}$$

où j est l'indice d'une dent quelconque. On a alors la possibilité de prédire selon une première manière le régime moteur à un angle déterminé du vilebrequin 2 ou selon une seconde manière à un temps fixé.If we consider that the angular width between each tooth 7 of the toothed wheel 4 is 6 °, we can therefore index the relation (10) as a function of a number j of teeth: $${\mathrm{NOT}}_{\mathrm{j}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}}^{\mathrm{2}}-{\mathrm{<figure-callout\; id="2"\; label="NOT\; j"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">NOT\; </figure-callout>}}_{\mathrm{j}}^{\mathrm{}}={\mathrm{VS}}_{\mathrm{0}}$$

where j is the index of any tooth. It is then possible to predict in a first manner the engine speed at a given angle of the crankshaft 2 or in a second manner at a fixed time.

• On détermine et on enregistre le régime de rotation réel du vilebrequin à des positions angulaires dudit vilebrequin pour une plage T de positions angulaires du vilebrequin 2 délimitée par une première position angulaire et une seconde position angulaire. Pour ce faire, on effectue un enregistrement des durées inter-dent, t_id, pour la période T considérée, le nombre d'enregistrement est donc dans notre exemple, des trente dernières durées inter-dent, t_id, soit un enregistrement sur une plage de 180°. De préférence, ici la seconde position angulaire correspond donc à la position à l'instant présent du vilebrequin 2.

The procedure for predicting an engine speed at a given angle of the crankshaft 2, in other words for a given number of teeth d of the toothed wheel 4 is as follows:

• The actual rotational speed of the crankshaft is determined and recorded at angular positions of said crankshaft for a range T of angular positions of the crankshaft 2 delimited by a first angular position and a second angular position. To do this, a recording of the inter-tooth durations, t _id , for the period T considered, the number of records is in our example, the last thirty inter-tooth durations, t _id , or a record on a range of 180 °. Preferably, here the second angular position corresponds to the position at the present moment of the crankshaft 2.

• On détermine la constante C₀ en fonction de l'écart des carrés des régimes réels déterminé pour les première et seconde positions angulaires, autrement dit par la différence entre le régime instantané au carré du premier enregistrement et le régime instantané au carré du dernier enregistrement.
• On détermine un régime prédit Ñ de rotation du vilebrequin 2 pour une troisième position angulaire du vilebrequin 2, non comprise dans la plage T de positions angulaires du vilebrequin 2, en fonction de la constante C₀ et du régime réel N déterminé à une quatrième position angulaire comprise dans ladite plage T et telle que l'écart entre les troisième et quatrième positions angulaires est un multiple supérieur ou égal à ladite plage (T). En effet, le régime prédit Ñ est déterminé sur la base d'une formule générale dont l'expression est maintenant démontrée :
  • Pour les besoins de la démonstration et comme illustré sur la figure 3 on attribue au dernier enregistrement l'indice n. Le premier enregistrement a donc l'indice (n-T/6).

The figure 3 presents in full line the recorded angular period T and indicates in dashed line the variation of the rotational speed to come. For each inter-tooth time, t _id , the real rotational speed is determined by the relation (1). The actual speed values are stored in the ECU 6 for their future use in the rest of the procedure.

• The constant C ₀ is determined as a function of the squared deviation of the actual regimes determined for the first and second angular positions, in other words by the difference between the instantaneous squared regime of the first record and the instantaneous squared regime of the last record.
• A predicted rotational speed of the crankshaft 2 is determined for a third angular position of the crankshaft 2, not included in the range T of angular positions of the crankshaft 2, as a function of the constant C ₀ and the real speed N determined at a fourth position. angular included in said range T and such that the difference between the third and fourth angular positions is a multiple greater than or equal to said range (T). Indeed, the predicted diet Ñ is determined on the basis of a general formula whose expression is now demonstrated:
  • For the purposes of the demonstration and as illustrated on the figure 3 the last record is assigned the index n. The first record therefore has the index (nT / 6).

In order to predict the tooth regime after the last recording, we can write: $${\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{d}}^{\mathrm{2}}-{\mathrm{NOT}}_{\mathrm{not}+\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">d</figure-callout>}}^{\mathrm{2}}={\mathrm{VS}}_{\mathrm{0}}$$

In the rest of the demonstration, in order to distinguish the values of the regime determined from the inter-teeth times of that not known and therefore to predict, we note N the first and Ñ seconds.

Thus for 0 <d ≤ T / 6, for example for d = 20 (see figure 3 ), the relation (12) becomes: $${\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{20}}^{\mathrm{2}}-{\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{20}}^{\mathrm{2}}={\mathrm{VS}}_{\mathrm{0}}$$

Is : $${\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{20}}^{\mathrm{2}}={\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{20}}^{\mathrm{2}}-{\mathrm{VS}}_{\mathrm{0}}$$

For T / 6 <d ≤ 2T / 6, we have for example for d = 50 (see figure 3 ), the relation (12) becomes: $${\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{50}}^{\mathrm{2}}={\widetilde{\mathrm{NOT}}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{50}}^{\mathrm{2}}-{\mathrm{VS}}_{\mathrm{0}}={\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{20}}^{\mathrm{2}}-{\mathrm{VS}}_{\mathrm{0}}=\left({\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{20}}^{\mathrm{2}}-{\mathrm{VS}}_{\mathrm{0}}\right)-{\mathrm{VS}}_{\mathrm{0}}={\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{20}}^{\mathrm{2}}-\mathrm{2}{\mathrm{VS}}_{\mathrm{0}}$$

For 2T / 6 <d ≤ 3T / 6, we have for example for d = 80 (see figure 3 ), the relation (12) becomes: $${\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{80}}^{\mathrm{2}}={\widetilde{\mathrm{NOT}}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{80}}^{\mathrm{2}}-{\mathrm{VS}}_{\mathrm{0}}={\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{50}}^{\mathrm{2}}-{\mathrm{VS}}_{\mathrm{0}}=\left({\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{20}}^{\mathrm{2}}-\mathrm{2}{\mathrm{VS}}_{\mathrm{0}}\right)-{\mathrm{VS}}_{\mathrm{0}}={\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{20}}^{\mathrm{2}}-\mathrm{3}{\mathrm{VS}}_{\mathrm{0}}$$

From these three examples, we can see that we can obtain a general expression of the predicted regime Ñ _{n + d} , d teeth after the n acquisitions. Indeed, by posing: $$\mathrm{AT}=\mathrm{INT}\left(\frac{\mathrm{6}\mathrm{d}}{\mathrm{T}}\right)$$

And $$\mathrm{B}=\mathrm{d}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}\cdot \mathrm{AT}$$

It comes, for an internal combustion engine comprising four cylinders, equipped with a toothed wheel of 58 teeth (that is to say a toothing of 60 teeth including 2 missing), the following general formula: $${\widetilde{\mathrm{NOT}}}_{\mathrm{not}+\mathrm{d}}=\sqrt{{\mathrm{NOT}}_{\mathrm{not}-\frac{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T</figure-callout>}}{\mathrm{6}}+\mathrm{B}}^{\mathrm{2}}-\left(\mathrm{AT}+\mathrm{1}\right)\cdot {\mathrm{VS}}_{\mathrm{0}}}$$

We now describe the complementary procedure for predicting engine speed at a fixed time tp during the end of rotation phase.

• l'étape d'enregistrement des durées inter-dent, t_id, pour la période T considérée,
• l'étape de détermination des régimes instantanés, à partir des durées inter-dent, t_id enregistrées.
• l'étape de détermination de la constante C₀.

We repeat the steps described above, that is to say:

• the step of recording inter-tooth durations, t _id , for the period T considered,
• the step of determining the instantaneous diets, from the inter-tooth durations, t _id recorded.
• the step of determining the constant C ₀ .

• Les régimes étant connus jusqu'à la dent d'indice n, on initialise la valeur d'un compteur de temps S à 0 pour la dent d'indice n.
  • on détermine le régime prédit à la dent suivante, d'indice n+1, référencé Ñ_n+1 sur la figure 4, à l'aide de la relation générale (19),
  • on calcule à partir du régime prédit à la dent d'indice n+1, un temps inter-dents, t_id, correspondant à partir de la relation (1), référencé t_n+1, sur la figure 4,
  • on incrémente le compteur de temps S du temps inter-dents calculé.
  • on réitère les précédentes étapes sur les dents d'indices suivants tant que la valeur du compteur de temps S est inférieure au temps fixé tp. Ainsi, comme le montre la figure 4, à l'indice n+2, le cumul des temps inter-dents cumulés à partir de l'indice n est inférieur au temps fixé tp tandis qu'à l'itération suivant, à l'indice n+3, le cumul des temps inter-dents, tid, est supérieur au temps fixé tp. On poursuit alors la procédure ainsi :
  • on détermine un régime prédit pour le temps fixé tp, par interpolation entre les régimes prédits pour les deux derniers indices, référencés respectivement Ñ_n+2. Ñ_n+3 sur la figure 4. On obtient ainsi un régime prédit Ñ_p au temps fixé t_p.

We proceed then step by step, as illustrated on the figure 4 :

• As the regimes are known up to the tooth of index n, the value of a time counter S is initialized to 0 for the tooth of index n.
  • determining the predicted diet at the next tooth, of index n + 1, referenced Ñ _{n + 1} on the figure 4 , using the general relation (19),
  • from the predicted regime at the tooth of index n + 1, an inter-tooth time, t _id , corresponding from the relation (1), referenced t _{n + 1} , is calculated on the figure 4 ,
  • the time counter S of the calculated inter-tooth time is incremented.
  • the preceding steps are reiterated on the following index teeth as long as the value of the time counter S is less than the set time tp. So, as shown in figure 4 at the index n + 2, the cumulative cumulative inter-tooth time from index n is less than fixed time tp while at the next iteration, at the index n + 3, the cumulation of inter-teeth times, tid, is greater than the set time tp. We then continue the procedure as follows:
  • a predicted regime is determined for the fixed time tp, by interpolation between the predicted regimes for the last two indices, referenced respectively Ñ _{n + 2} . Ñ _{n + 3} on the figure 4 . This gives a predicted regime Ñ _p at the set time t _p .

Advantageously, this procedure can make it possible to determine the stop cylinder. Stop cylinder means the cylinder which is in the compression phase of the engine cycle.

• On reprend les étapes décrites précédemment, c'est-à-dire :
  • l'étape d'enregistrement des durées inter-dent, t_id, pour la période T considérée,
  • l'étape de détermination des régimes réels, à partir des durées inter-dent, t_id enregistrées, à l'aide de la relation (1).
  • l'étape de détermination de la constante C₀.
  • on calcule le régime réel au point mort haut (ou PMH) combustion, nommé N_PMH à partir de l'enregistrement du temps inter-dents correspondant.

To do this, we proceed as follows:

• We repeat the steps described above, that is to say:
  • the step of recording inter-tooth durations, t _id , for the period T considered,
  • the step of determining the real diets, from the inter-tooth durations, t _id recorded, using the relation (1).
  • the step of determining the constant C ₀ .
  • the actual top dead center (or TDC) combustion regime is calculated, named N _PMH from the corresponding inter-tooth time record.

• On prédit de proche en proche le régime pour des positions angulaires correspondant aux prochains PMH combustion, comme l'illustre la figure 5 l'estimation du régime dans k PMH combustion étant donnée par la relation suivante : $${\tilde{\mathrm{<figure-callout\; id="2"\; label="N\; ̃\; PMH\_k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">N</figure-callout>}}}_{\mathrm{PMH\_k}}^{\mathrm{}}={\mathrm{<figure-callout\; id="2"\; label="N\; PMH"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">N</figure-callout>}}_{\mathrm{PMH}}^{\mathrm{}}-{\mathrm{kC}}_{\mathrm{0}}$$
  

Then, as follows, with a range T of angular position:

• The regime is gradually predicted for angular positions corresponding to the next combustion PMH, as illustrated by FIG. figure 5 the estimation of the regime in k combustion PMH being given by the following relation: $${\widetilde{\mathrm{NOT}}}_{\mathrm{<figure-callout\; id="2"\; label="PMH\_k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">PMH\_k</figure-callout>}}^{\mathrm{2}}={\mathrm{NOT}}_{\mathrm{TDC}}^{\mathrm{2}}-{\mathrm{kC}}_{\mathrm{0}}$$
  

This until the moment when we will not be able to cross the PMH combustion, which corresponds to the minimum value of k such that: $${\mathrm{NOT}}_{\mathrm{TDC}}^{\mathrm{2}}-{\mathrm{kC}}_{\mathrm{0}}<\mathrm{0}$$

Is $$\mathrm{k}=\mathrm{<figure-callout\; id="2"\; label="INT\; NOT\; TDC"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">INT\; </figure-callout>}\left(\frac{{\mathrm{NOT}}_{\mathrm{TDC}}^{}}{}\right)\left(\frac{{\mathrm{}}_{\mathrm{2}}^{}}{{\mathrm{VS}}_{\mathrm{0}}}\right)$$

With INT (x) the whole part function.

In this case it is concluded that the motor will go to PMH combustion before stopping, which allows to deduce the stopping cylinder.

The invention is not limited to a particular type of combustion engine. In the case of an internal combustion engine comprising three cylinders, the range T of angular positions of the crankshaft 2 is preferably 240 ° or 720 °, due to the phase shift of the engine cycles of the various cylinders.

In the case of an internal combustion engine comprising six cylinders, the range T of angular positions of the crankshaft 2 is preferably 120 °, 240 ° or 720 °, due to the phase shift of the engine cycles of the various cylinders.

The invention has the advantage of being simple to set up as a computer routine programmed in the ECU and does not require any particular calibration.

Claims (9)

1. A method for prediction of the rotation speed of a crankshaft (2) of an internal combustion engine (2) in the end of rotation phase, characterized in that:

   - The actual rotation speed (N) of the crankshaft (2) is determined and recorded at angular positions of said crankshaft for a range (T) of angular positions of the crankshaft (2) delimited by a first angular position and a second angular position corresponding to periodic oscillations in an angular manner of reduction of the rotation speed (N) of the crankshaft (2).

   - A constant (C₀) is determined as a function of the deviation of the squares of the actual speeds determined for the first and second angular positions.

   - A predicted rotation speed (N) of the crankshaft (2) is determined for a third angular position of the crankshaft (2), not included in the range (T) of angular positions of the crankshaft (2), as a function of the constant (C₀) and of the actual speed (N) determined at a fourth angular position comprised in said range (T) and such that the deviation between the third fourth angular positions is equal to said range (T) or is a multiple thereof.
2. The method according to Claim 1, characterized in that the second angular position corresponds to the position at the present instant of the crankshaft (2) which is the last angular position for which an actual speed can be determined.
3. The method according to Claim 1 or Claim 2, characterized in that, the engine including four cylinders, the range (T) of angular positions of the crankshaft (2) is 180°, 360° or 720°.
4. The method according to Claim 3, characterized in that the range (T) is 360°.
5. The method according to Claim 1 or Claim 2, characterized in that, the engine including three cylinders, the range (T) is 240° or 720°.
6. The method according to Claim 1 or Claim 2, characterized in that, the engine including six cylinders, the range (T) is 120°, 240° or 720°.
7. The method according to any one of the preceding claims, the crankshaft (2) being integral in rotation with a toothed wheel (4) including teeth (7) serving to determine the angular position of said crankshaft (2), the angular width between each tooth (7) being 6°, characterized in that the predicted rotation speed (N) of the crankshaft (2) for the third angular position of the crankshaft (2) is determined as a function of the actual speed (N) by applying the following relationship: $${\tilde{\mathrm{N}}}_{\mathrm{n}+\mathrm{d}}=\sqrt{{\mathrm{N}}_{\mathrm{n}-\frac{\mathrm{T}}{\mathrm{6}}+\mathrm{B}}^{\mathrm{2}}-\left(\mathrm{A}+\mathrm{1}\right)\cdot {\mathrm{C}}_{\mathrm{0}}}$$

   

   in which:

   A and B are variables such that:

   $$\mathrm{A}=\mathrm{INT}\left(\frac{\mathrm{6}\mathrm{d}}{\mathrm{T}}\right)\mathrm{et\; B}=\mathrm{d}-\frac{\mathrm{T}}{\mathrm{6}}\cdot \mathrm{A}$$

   

   n is the index of the tooth (7) marking the second angular position of the crankshaft (2), n+d is the index of the tooth (7) marking the third angular position of the crankshaft (2),

   $$\mathrm{n}-\frac{\mathrm{T}}{\mathrm{6}}+\mathrm{B}$$

   

   is the index of the tooth (7) marking the fourth angular position of the crankshaft (2),

   and INT is the whole fraction function.
8. The method according to Claim 7, characterized in that it further includes the following steps:

   - the predicted speed (N) is determined at the tooth (7) of index n+1,

   - from the predicted speed (N) of the tooth of index n+1, an inter-tooth time (t_id) is calculated,

   - a time counter (S) is incremented of the calculated inter-tooth time (t_id),

   - the preceding steps are repeated on the teeth (7) of following indices as long as the value of the time counter (S) is less than a fixed time (tp),

   - a predicted speed is determined for the fixed time (tp), by interpolation between the predicted speeds for the last two indices.
9. An application of the method according to any one of Claims 1 to 7 to the prediction of the stop cylinder of an internal combustion engine, characterized in that the third angular position of the crankshaft (2) corresponds to a combustion top dead centre.

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