Improved method for synchronizing a heat engine using a camshaft target.

Abstract

The invention relates to a method for determining the angular position of an irregularly toothed camshaft target. A sensor generates a signal at each tooth passage, creating significant cutting edges. A processing unit processes this signal to determine the time intervals between these edges, stores theoretical ratios, tolerance intervals, and confidence intervals. Suspicion counters are associated with each edge. By calculating actual ratios based on the measured intervals, the unit discriminates between candidate edges: edges not within tolerances are eliminated, those within confidence intervals reset the suspicion counter, and those outside confidence intervals increase the suspicion counter until they are eliminated. These steps are repeated until a single candidate edge is identified. The angular position of the target is then determined from this single edge.Figure for the abbreviation: Figure 2.

Description

Title of the invention: Improved method for synchronizing a heat engine using a camshaft target. Scope of the invention

[0001] The present invention relates to an improved method of synchronizing a heat engine by means of a camshaft target. Previous art

[0002] An internal combustion engine must be phased, or synchronized, in order to determine and optimize the best time to burn the fuel in the cylinder, i.e. to optimize in particular fuel consumption.

[0003] Throughout the text, synchronization refers to the determination of the angular position of the internal combustion engine during the combustion cycle.

[0004] The cycle of an internal combustion engine comprises several phases whose occurrence is staggered in time for each cylinder, the synchronized control of the valves of the heat engine being achieved by the camshaft.

[0005] In order for the combustion cycle to proceed normally, it is necessary to have a reliable angular reference on the basis of which each phase of each cylinder is determined.

[0006] The camshaft is driven in rotation by the crankshaft. The crankshaft is a mechanical device which, by means of a connecting rod, transforms the rectilinear motion of a piston into a continuous rotational motion, and vice versa, thus ensuring the transmission of the combustion energy of the fuel in the cylinders into mechanical energy.

[0007] Thus, knowledge of the angular position of the crankshaft makes it possible to know a reliable angular reference on the basis of which each phase of each cylinder is determined.

[0008] Such a reference is available via a toothed wheel, also called a target, which is fixed to the crankshaft for rotation. The wheel is associated with a dedicated sensor, called a crankshaft sensor, whose ultimate role is to determine the angular position and rotational speed of the toothed wheel. The sensor is equipped with a sensing element. For example, the wheel is metallic and the sensing element is capable of detecting metal, such as a Hall effect sensor. The wheel profile typically includes a target with markings, also called teeth, distributed around its periphery. The crankshaft sensor's function is to transform the measured magnetic field into an electrical signal. According to the prior art, some sensors are connected to the control unit by three wires (ground, power supply, and signal). and possess the ability to determine the direction of rotation of a crankshaft target. The passage of a tooth on the sprocket associated with the crankshaft generates an electrical pulse on the signal wire. The predetermined duration is representative of the direction of rotation (typically 45 ps for forward rotation and 90 ps for reverse rotation). The crankshaft sensor is typically mounted near the flywheel that serves as the rotating target or supports such a target.

[0009] The rotating target has a signature, also called a long tooth or gap, formed by a singularity in the (otherwise regular) profile, usually corresponding to two missing reference marks, which allows a reference to be established for the crankshaft position. Such a signature generates a signal different from the other reference marks, which makes it possible to determine when the rotating target has completed a full rotation.

[0010] A commonly used rotating target comprises 60 markers distributed around the periphery of the rotating target, and two consecutive markers removed to create the signature. Such a target is called a 60-2 rotating target. Another known rotating target is the 36-2 rotating target (34 markers plus two missing markers).

[0011] The rotation of the rotating target causes periodic changes in the magnetic flux due to the passage of the markers, which are transformed by the sensor into voltage variations that can subsequently be sent to the engine control unit. The voltage variations include rising and falling edges forming a periodic signal synchronized with the passage of the markers in front of the sensor.

[0012] During engine rotation, the crankshaft axis makes two rotations while the camshafts make only one.

[0013] Additional information is thus obtained using the camshaft sensor. The camshaft sensor cooperates, in a manner known per se, with a disc-shaped camshaft target, which is mounted integrally with the camshaft. The camshaft target is toothed around its periphery, possibly with an irregular tooth distribution. In particular, the teeth may be irregularly spaced and / or of different lengths (the length of a tooth corresponding to its angular extent along the circumference of the camshaft target). The camshaft target thus exhibits an asymmetry, making it possible to achieve correct phasing, that is, to determine with certainty where each cylinder is positioned in the combustion cycle. The position of the camshaft target is estimated by the camshaft sensor, which detects the times when the teeth pass over said camshaft sensor. cams.

[0014] In practice, the camshaft sensor generates a signal taking a low value in the absence of a tooth at the said sensor, and a high value in the presence of a tooth at the said sensor.

[0015] The transition between the low and high values ​​of the signal forms a rising edge of the signal, associated with the detection of a rising edge of a tooth on the camshaft target. The transition between the high and low values ​​of the signal forms a falling edge of the signal, associated with the detection of a falling edge of a tooth on the camshaft target.

[0016] Prior art synchronization methods compare information obtained using the camshaft sensor with information obtained using the crankshaft sensor, so as to determine the engine position.

[0017] However, the methods are based on the recognition of the crankshaft target signature, so they are ineffective in the event of crankshaft sensor failure or possibly in the event of high acceleration.

[0018] Another synchronization method is known that compensates for the failure of the crankshaft sensor, based on an identification of the tooth of the camshaft target which is located at the right of the camshaft sensor, described in document FR2991720, the main steps of which are described below.

[0019] This other synchronization method is based on measuring time intervals separating significant edges of the signal generated by the camshaft sensor, and on using ratios between several of these measured time intervals.

[0020] Each tooth of the camshaft target is designated by its index i, where i is an integer from 1 to M, the number of teeth on the camshaft target.

[0021] A theoretical ratio CP(j), j ranging from 1 to M, is calculated from known angular deviations P(j) between tooth faces of the camshaft target, using the formula below: [Math. 1]

[0022] where P(j) denotes the angular distance between the significant front j and the preceding front,

[0023] where N is called the order of calculation of the index. It is an integer greater than or equal to 1. In the simplest case, we will take N = 1. In special cases, we may take N = 2 or even N = 3.

[0024] For N = 1, the expression for CP(j) simplifies to: [Math. 2] CPQ) = CP(j) = P(j) + PÜ~3) PQ - 2) + P(j - 1)

[0025] The computing unit is configured to calculate time intervals Tk separating two significant edges following each other immediately on said signal;

[0026] As soon as possible, the following index is calculated: [Math. 3] _ [Sf-I + ~ j) ZjI—n * *. '•)

[0027] where T(k) is the duration of the time interval between the significant front k and the previous significant front.

[0028] 4N + 1 fronts must be waited for in order to calculate the above index. It is therefore relevant to choose the order N = 1 in order to calculate such an index after 4N intervals between fronts, i.e. at the fifth front when N = 1. The index is thus a ratio of time intervals.

[0029] When N is chosen to have the value N = 1, the expression for CT(k) simplifies to: [Math. 4] = T(k) + T(k-3) 1 () T(k - 2) + T(k - 1) .A < ±

[0030] CT(k) is thus a real ratio equivalent to the theoretical ratio CP(j), but based on time interval measurements on the signal generated by the camshaft sensor.

[0031] In other words, the definition of CT(k) is similar to the definition of the actual ratio CP(j) except that the known angular deviations between the significant fronts of the camshaft target teeth are replaced by time intervals Tk. Therefore, an uncertainty must be tolerated, represented by a margin of uncertainty coefficient, also called the tolerance coefficient Ck.

[0032] If the rotational speed of the motor is constant, then we have CT(j)=CP(j) for j from 1 to M. In reality, when the motor rotates, and in particular during the first revolutions, the rotational speed is not constant.

[0033] In order to take into account the acyclisms of the engine, and / or the variations in acceleration at start-up, it is customary to compare the calculated CT(k) index to each of the CP(j) characteristics, and in particular to INT(j) intervals respectively framing each CP(j).

[0034] INT(j) corresponds to the following interval: ^.CkCPQ)

[0035] Following these comparisons, we eliminate from the sublist the fronts j for which the index CT(k) is outside the interval INT(j).

[0036] By iterating the process, it is thus possible to gradually eliminate the hypotheses deemed unrealistic, until only one plausible value remains for the index of the camshaft target tooth commonly located with regard to the sensor.

[0037] The Ck ratio must be high enough to withstand strong oscillations when starting the motor, but too high a value prevents the detection of a reverse rotation.

[0038] Indeed, when the engine changes direction of rotation, the synchronization between two consecutive edges of the camshaft may not be representative of the correct angular distance, due to the strong deceleration of the engine, and the synchronization may be falsely maintained due to a ratio factor that is too high.

[0039] The ratio is therefore difficult to estimate.

[0040] This invention proposes a faster method for determining the synchronization of the motor, regardless of the ratio method used (angular or temporal).

[0041] The invention aims to overcome the disadvantages of the prior art and in particular to reduce the synchronization time in the event of failure of the crankshaft sensor.

[0042] Indeed, the angular position of the engine is determined from the acquisition of the known (defined) edge of the crankshaft signal, by interpolating the position between the acquisition time and the estimated arrival of the next edge. For a 60-2 type target, the angular spacing is 6° between two teeth and 18° in the signature zone. In degraded mode (i.e., when the crankshaft signal is faulty), the position is calculated from the acquisition of the known camshaft edge. Similarly, the position is estimated by interpolating the acquisition position, the position of the next edge expected to arrive, and the time elapsed since the last acquisition. Description of the invention

[0043] To this end, according to a first aspect of the invention, a method is proposed for determining the angular position of a camshaft target mounted integrally with a camshaft and having a plurality of teeth distributed angularly and irregularly around the periphery of the target, the method being implemented by a computing unit configured to:

[0044] acquire a signal generated by a sensor associated with the camshaft target, said sensor being configured to detect the passage of the teeth of the camshaft target and to generate in response a signal comprising rising edges and falling edges descendants associated respectively with ascending or descending fronts of said teeth,

[0045] the plurality of teeth forming, for the sensor, a series of significant fronts when the camshaft rotates by one revolution, each significant front being associated with a predetermined index allowing it to be identified; and

[0046] calculate time intervals separating two significant fronts following each other immediately on said signal;

[0047] store, for each front j, M significant fronts:

[0048] • a theoretical ratio CP(j), j ranging from 1 to M, determined from angular deviations P(j) known between significant known fronts of the camshaft target,

[0049] • an associated tolerance interval INT(j), a function of the value taken by the ratio theoretical CP(j) and a tolerance factor Ck,

[0050] • an associated confidence interval INTC(j), a function of the value taken by the ratio theoretical CP(j) and a confidence factor Ce, the confidence factor being less than the tolerance factor Ck,

[0051] • associate a suspicion counter S(j) and its initialization with the value zero,

[0052] The computing unit is further configured to:

[0053] / a / define a list of candidate fronts consisting of all the fronts significant,

[0054] / b / determine a current value taken by a real ratio CT(k) as a function of a first a set of time intervals Tk, where the definition of the actual ratio CT(k) is similar to the definition of the theoretical ratio CP(j) except that the known angular deviations are replaced by the corresponding time intervals Tk between significant fronts,

[0055] / c / a discrimination step, comprising,

[0056] for each front j in the list of candidate fronts:

[0057] • if the current value taken by the real ratio CT(k) does not belong to the interval of tolerance INT(j) associated with said front j: a deletion of said front j from the list of candidate fronts, the suspicion counter S(j) then being assigned a predetermined value called maximum,

[0058] • otherwise, if the current value taken by the real ratio CT(k) is outside the interval of confidence INTC(j) associated with said front j: an increment of the current value of the suspicion counter S(j) associated with said front from the list, then the removal of said front j from the list of candidate fronts when the suspicion counter is greater than the predetermined maximum value,

[0059] / d / wait for the reception of a new significant front, replace each front j with the list by its immediate successor j+1 modulo M, then repeat steps / b / and / c / until a single candidate front is obtained in the list of significant fronts,

[0060] the angular position of the camshaft target being then determined from the angular position of the only significant front in the list of candidate fronts.

[0061] In an advantageous embodiment, during step / d / , steps / b / and / c / are repeated until a single candidate front is obtained in the list of significant fronts, or until a single candidate front is found in the list of significant fronts with a suspicion counter of zero. This second condition allows for faster convergence.

[0062] Preferably, for each of the M significant fronts, the theoretical ratios CP(j), j ranging from 1 to M, are defined by: [Math. 5] EUpü -1 +1) - p(J - 0] U =l------------------------1....

[0063] where P(j) denotes the angular distance between the significant front j and the preceding front,

[0064] where N is an integer greater than or equal to 1 called the index calculation order,

[0065] and the real ratio CT(k), k ranging from 1 to M, are defined by: [Math. 6] rTf ,, _ Eli T(k - i + 1) - SSU - 01 US^T(ki) L

[0066] where T(k) is the duration of the time interval between the significant front k and the previous significant front.

[0067] Advantageously, N=l, the expressions for CP(j) and CT(k) becoming: [Math. 7] [pq)+Pü-3) 0) [pQ-Zl + PÜ-l)]^

[0068] and [Math. 8] CT(k) = T(k) + T(k-3) T(k - 2) + T(k - 1)

[0069] The tolerance factor Ck can be chosen to be greater than or equal to 2.1.

[0070] The confidence factor Ce is preferably less than or equal to 1.8.

[0071] Advantageously, the significant fronts following each other immediately are rising or falling fronts.

[0072] According to one aspect of the invention, a computer program is proposed comprising program code instructions for executing the steps of the synchronization process according to the first aspect of the invention, when said program is running on a computer.

[0073] According to yet another aspect of the invention, a module is proposed for determining the angular position of a camshaft target mounted integrally with a camshaft and having a plurality of teeth distributed angularly and irregularly around the periphery of the target, comprising a calculation unit configured for:

[0074] acquire a signal generated by a sensor associated with the camshaft target, said sensor being configured to detect the passage of the teeth of the camshaft target and to generate in response a signal comprising rising edges and falling edges associated respectively with rising edges or falling edges of said teeth,

[0075] the plurality of teeth forming, for the sensor, a series of M significant fronts when the camshaft rotates by one revolution, each significant front being associated with a predetermined index allowing it to be identified; and

[0076] calculate time intervals separating two significant fronts of a series of M significant fronts following each other immediately on said signal;

[0077] store, for each of the M significant fronts:

[0078] • a theoretical ratio CP(j), j ranging from 1 to M, determined from angular deviations P(j) known, between known significant fronts of the camshaft target tooth,

[0079] • an associated tolerance interval INT(j), a function of the value taken by the ratio theoretical CP(j) and a tolerance factor Ck,

[0080] • an associated confidence interval INTC(j), a function of the value taken by the ratio theoretical CP(j) and a confidence factor Ce, the confidence factor being less than the tolerance factor Ck,

[0081] • associate a suspicion counter S(j) and its initialization with the value zero,

[0082] The computing unit is further configured to:

[0083] / a / define a sublist of significant fronts consisting of the set of fronts significant,

[0084] / b / determine a current value taken by a real ratio CT(k) as a function of a first set of time intervals Tk, where the definition of the actual ratio CT(k) is similar to the definition of the theoretical ratio CP(j) except that the known angular deviations are replaced by the corresponding time intervals Tk between the significant fronts of the camshaft target teeth,

[0085] / c / discriminate, for each front j in the list of candidate fronts:

[0086] • if the current value taken by the real ratio CT(k) does not belong to the interval of tolerance INT(j) associated with said front j: a removal of said front j from the list of candidate fronts, then

[0087] • otherwise, if the current value taken by the real ratio CT(k) is outside the interval confidence INTC(j) associated with said front: an increment of the current value of the suspicion counter S(j) associated with said front from the list, then the removal of said front j from the list of candidate fronts when the suspicion counter is greater than the maximum value,

[0088] wait for the reception of a new significant front, replace each front j in the list with its immediate successor j+1 modulo M, then repeat steps / b / and / c / until a single significant front is obtained in the list of significant fronts,

[0089] determine the angular position of the camshaft target from the angular position of the only significant front in the list of candidate fronts.

[0090] According to another aspect of the invention, a motor vehicle comprising a module according to the invention is proposed. Brief description of the figures

[0091] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings, in which: • [Fig-1] illustrates an embodiment of a module according to the invention and its physical environment, and • [Fig. 2] illustrates an embodiment of a process according to the invention, • [Fig.3] illustrates intervals used in the process of [Fig.2]. Detailed description of the invention

[0092] With reference to the figures, an embodiment of a method P for determining the angular position of a camshaft target C of a vehicle engine is now described, together with an angular position determination module and a vehicle equipped with said module.

[0093] The camshaft target C is mounted integrally to a camshaft A and has a plurality of teeth distributed irregularly around the circumference of the camshaft. A target having a plurality of teeth distributed angularly and regularly except for one or more particular areas is a target whose teeth are distributed irregularly. This is, for example, the case of a target having 60 teeth distributed regularly except for an area in which one or two teeth are missing. In other words, a target having a regular distribution and a or several irregularities is a target exhibiting a plurality of teeth distributed irregularly.

[0094] The sensor S is typically associated with the target C mounted fixed to the rotation of the camshaft A.

[0095] The camshaft target C has a plurality of teeth distributed irregularly around the circumference of the camshaft A, each tooth being associated with a predetermined index allowing it to be identified.

[0096] The sensor S is configured to detect the passage of the teeth of the camshaft target C and to generate in response a signal comprising rising and falling edges associated respectively with the rising and falling edges of said teeth. Such a signal is shown in the following figures.

[0097] The computing unit Uc is configured to acquire a signal generated by the camshaft sensor S.

[0098] For the remainder of the description, the concept of a significant edge is introduced; a significant edge is a type of edge that is processed by the identification logic implemented in the computing unit Uc. For some types of camshaft targets, the significant edges are the rising and falling edges, whereas for other types of camshaft targets, only the rising or falling edges are significant edges. For some targets, the immediately following significant edges are falling edges.

[0099] The number of significant fronts on a camshaft target revolution is denoted M in the following.

[0100] The computing unit Uc is also configured to calculate time intervals Tk separating two significant edges following each other immediately on the signal.

[0101] Theoretical ratios

[0102] The calculation unit is further configured to store, for each of the M significant fronts, a theoretical ratio CP(j), j ranging from 1 to M, determined from known angular deviations P(j), between known significant fronts of the camshaft target tooth.

[0103] As in the prior art, the theoretical ratios CP(j), j ranging from 1 to M, can be defined by: [Math. 9] CPQ) = "ai

[0104] where P(j) denotes the angular distance between the significant front j and the previous front,

[0105] where N is an integer greater than or equal to 1 called the order of calculation of the index. cpQ) =

[0106] Preferably, N=l, and the expression CP(j) becomes: [Math. 10] P(j) + P(j-3) P(j - 2) + P(J - However, other theoretical ratios can be used.

[0107] With reference to [Fig.2], the computing unit is further configured to

[0108] / a / define a list of candidate fronts consisting of all the fronts significant,

[0109] / b / determine a current value taken by a real ratio CT(k) as a function of a first set of time intervals Tk, where the definition of the real ratio CT(k) is similar to the definition of the theoretical ratio CP(j) except that the known angular deviations are replaced by the corresponding time intervals Tk between significant fronts,

[0110] / c / discriminate, for each front j of the list of candidate fronts:

[0111] • if the current value taken by the real ratio CT(k) does not belong to the interval of tolerance INT(j) associated with said front j: a removal of said front j from the list of candidate fronts, then

[0112] • otherwise, if the current value taken by the real ratio CT(k) belongs to the interval of INTC(j) confidence associated with front-end audit: a reset of the suspicion counter S(j) to zero when j, then

[0113] • otherwise: an increment of the current value of the suspicion counter S(j) associated with said front from the list, then the removal of said front j from the list of candidate fronts when the suspicion counter is greater than a predetermined number,

[0114] / d / wait for the receipt of a new significant front, replace each front j with the list by its immediate successor j+1 modulo M, then repeat steps / b / and / c / until a single candidate front is obtained in the list of significant fronts,

[0115] the angular position of the camshaft target being then determined from the angular position of the only significant front in the list of candidate fronts.

[0116] Preferably, each interval INT(j) is delimited by a lower bound and an upper bound, with: • the lower bound equal to the quotient of the value taken by the theoretical ratio CP(j) divided by a tolerance factor Ck, and • the upper bound equal to the product of the value taken by the theoretical ratio CP(j) multiplied by the tolerance factor Ck.

[0117] The tolerance interval INT (j) is defined by a lower bound Vinf and an upper bound Vsup, with Vinf=CP(j) / Ck and Vsup=CP(j)*Ck.

[0118] Preferably, the INTC(j) confidence interval is delimited by a lower bound and an upper bound, with: • the lower bound equal to the quotient of the value taken by the theoretical ratio CP(j) divided by a confidence factor Ce, and • the upper bound equal to the product of the value taken by the theoretical ratio CP(j) multiplied by the confidence factor Ce.

[0119] The confidence interval INTC(j) is defined by a lower bound VinfC and an upper bound VsupC, with Vinfc= CP(k) / Cc and VsupC= CP(k)*Cc.

[0120] Fig. 3 illustrates confidence intervals INTC(j) and tolerance intervals INT(j) centered around a theoretical ratio CP(j), the interval INTC(j) being included in the interval INT(j).

[0121] The interval INTC(j) is delimited by the lower bound VinfC and the upper bound VsupC, the interval INT(j) being delimited by the lower bound Vinf and the upper bound v'sup*

[0122] According to one possibility, step / d / may further include an additional condition for stopping the iterations of steps / b / and / c / and then proceeding to step ld, the additional condition being that only one candidate front in the list of significant fronts has a suspicion counter whose value is zero.

[0123] As in the prior art, the real ratios CT(k), k ranging from 1 to M, can be defined by: [Math. 11] _ K,T(k - i + 1) - S, 1 T(k - i)l = L ] Wîl where T(k) is the duration of the time interval between significant front k and the previous significant front.

[0124] Preferably, N=l, and the expression CP(j) becomes: [Math. 12] - [-^)+21^220 1 J [r(t - 2) + T(k - l)] w>1 Preferably, the tolerance factor Ck is greater than or equal to 2.1, or even greater than or equal to 2.5 or even greater than or equal to 2.8.

[0125] Preferably, the confidence factor is less than or equal to 1.8.

[0126] The module M according to the invention can be implemented as an electronic module comprising a memory in which a program product is stored computer containing instructions intended to be executed by the computer processing unit (CPU) or by the engine control unit (ECU), which then replaces the CPU.

[0127] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention. Furthermore, the various features, forms, variants, and embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive.

Claims

1. Demands Method (P) for determining the angular position of a camshaft target (C) mounted integrally with a camshaft (A) and having a plurality of teeth distributed angularly and irregularly around the periphery of the target, the method being implemented by a computing unit (Uc) configured to: acquire a signal generated by a sensor (S) associated with the camshaft target, said sensor being configured to detect the passage of the teeth of the camshaft target and to generate in response a signal comprising rising edges and falling edges associated respectively with rising edges or falling edges of said teeth, the plurality of teeth forming, for the sensor, a series of M significant fronts when the camshaft rotates one revolution, each significant front being associated with a predetermined index allowing its identification; and calculate time intervals separating two significant fronts following each other immediately on said signal; store, for each front j, M significant fronts: • a theoretical ratio CP(j), j ranging from 1 to M, determined from known angular deviations P(j) between known significant faces of the camshaft target, • an associated tolerance interval INT(j), a function of the value taken by the theoretical ratio CP(j) and a tolerance factor Ck, • an associated confidence interval INTC(j), a function of the value taken by the theoretical ratio CP(j) and a confidence factor Ce, the confidence factor Ce being less than the tolerance factor Ck, • associate a suspicion counter S(j) and its initialization with the value zero, The computing unit is further configured to: / a / define a list of candidate fronts consisting of all significant fronts, / b / determine a current value taken by a real ratio CT(k) as a function of a first set of time intervals Tk, where the The definition of the actual ratio CT(k) is similar to the definition of the theoretical ratio CP(j) except that the known angular deviations are replaced by the corresponding time intervals Tk between significant fronts, / c / a discrimination step, comprising, for each front j in the list of candidate fronts: • if the current value taken by the actual ratio CT(k) does not belong to the tolerance interval INT(j) associated with said front j: a removal of said front j from the list of candidate fronts, the suspicion counter S(j) then being assigned a predetermined value called maximum, then • otherwise, if the current value taken by the actual ratio CT(k) is outside the confidence interval INTC(j) associated with said front: an increment of the current value of the suspicion counter S(j) associated with said front from the list, then the removal of said front j from the list of candidate fronts when the suspicion counter is greater than the maximum value, / d / wait for the reception of a new significant front, replace each front j in the list with its immediate successor j+1 modulo M, then repeat steps / b / and / c / until a single candidate front is obtained in the list of significant fronts, ld the angular position of the camshaft target is then determined from the angular position of the single significant front in the list of candidate fronts.

2. A method according to the preceding claim, wherein in step / d / , steps / b / and / c / are repeated until a single candidate front is obtained in the list of significant fronts or a single candidate front is obtained in the list of significant fronts having a suspicion counter whose value is zero.

3. A method according to the preceding claim, wherein for each of the M significant fronts, the theoretical ratios CP(j), j ranging from 1 to M, are defined by: [Math. 13] CP (j) = X^PÜ-i) where P(j) denotes the angular distance between the significant front j and the preceding front, where N is an integer greater than or equal to 1, called the index calculation order, and the real ratio CT(k), k ranging from 1 to M, are defined by: [Math. 14] EL T(k - i +1) - £%$ T(k - i)' where T(k) is the duration of the time interval between significant front k and the previous significant front.

4. A method according to the preceding claim, wherein N=l, the expressions for CP(j) and CT(k) becoming: [Math. 15] [ PQ') + P(k-3) and [Math. 16] , = [ rw + r(k-3) ] ' 1 ' [r(k - 2) + T(k - 1)JK>1

5. A method according to the preceding claim, wherein the tolerance factor is greater than or equal to 2.

1.

6. A method according to the preceding claim, wherein the confidence factor is less than or equal to 1.

8.

7. A method according to any one of the preceding claims, wherein the significant fronts following each other immediately are descending or ascending fronts.

8. A computer program comprising program code instructions for carrying out the steps of the process of

9. synchronization according to any one of the preceding claims, when said program is running on a computer. Module (M) for determining the angular position of a camshaft target (C) mounted integrally with a camshaft (A) and having a plurality of teeth distributed angularly and irregularly around the periphery of the target, comprising a calculation unit (Uc) configured for: acquire a signal generated by a sensor (S) associated with the camshaft target, said sensor being configured to detect the passage of the teeth of the camshaft target and to generate in response a signal comprising rising edges and falling edges associated respectively with rising edges or falling edges of said teeth, the plurality of teeth forming, for the sensor, a series of M significant fronts when the camshaft rotates one revolution, each significant front being associated with a predetermined index allowing its identification; and calculate time intervals separating two significant fronts of a series of M significant fronts following each other immediately on said signal; store, for each of the M significant fronts: • a theoretical ratio CP(j), j ranging from 1 to M, determined from known angular deviations P(j), between known significant fronts of the camshaft target tooth, • an associated tolerance interval INT(j), a function of the value taken by the theoretical ratio CP(j) and a tolerance factor Ck, • an associated confidence interval INTC(j), a function of the value taken by the theoretical ratio CP(j) and a confidence factor Ce, the confidence factor Ce being less than the tolerance factor Ck, • associate a suspicion counter S(j) and its initialization with the value zero, The computing unit is further configured to: / a / define a sublist of significant fronts consisting of the set of significant fronts,

10. / b / determine a current value taken by a real ratio CT(k) as a function of a first set of time intervals Tk, where the definition of the real ratio CT(k) is similar to the definition of the theoretical ratio CP(j) except that the known angular deviations are replaced by the corresponding time intervals Tk between the significant fronts of the camshaft target teeth, / c / discriminate, for each front j of the list of candidate fronts: • if the current value taken by the actual ratio CT(k) does not belong to the tolerance interval INT(j) associated with said front j: a removal of said front j from the list of candidate fronts, the suspicion counter S(j) then being assigned a predetermined value called maximum, then • otherwise, if the current value taken by the actual ratio CT(k) is outside the confidence interval INTC(j) associated with said front: an increment of the current value of the suspicion counter S(j) associated with said front from the list, then the removal of said front j from the list of candidate fronts when the suspicion counter is greater than the maximum value, / d / wait for the receipt of a new significant front, replace each front j in the list with its immediate successor j+1 modulo M, then repeat steps / b / and / c / until a single significant front is obtained in the list of significant fronts, ld determine the angular position of the camshaft target from the angular position of the single significant front in the list of candidate fronts. Motor vehicle comprising a module according to the preceding claim.

Images