A toothed wheel for a camshaft of a three-, four- or six-cylinder engine with variable valve timing.

Abstract

The subject of the invention is a toothed wheel (1) of a camshaft (91) forming a target for a rotation sensor (2) of the camshaft, the toothed wheel (1) comprising a plurality of teeth (10) distributed over its circumference, the toothed wheel (1) comprising a first group (13) of four teeth each spaced 90° apart; and a second group (14) of six teeth each spaced 60° apart, the teeth of each group (13, 14) being distributed so that the wheel comprises at least two portions (16; 20) of its circumference which do not comprise an effective tooth edge over an angle of at least 35° and are spaced 180° apart, characterised in that the teeth of the first group (13) of teeth and the second group (14) of teeth are arranged so that the first group (13) of teeth and the second group (14) of teeth do not have any common teeth.

Description

Technical Field

[0001] The invention relates to a toothed wheel of a camshaft forming a target for a sensor for the angular position of the camshaft, for a three-, four- or six-cylinder engine. The invention is particularly suitable for engines of the variable valve timing type. Background Art

[0002] During the operating cycle of an internal combustion engine, the position of the crankshaft needs to be known precisely in order to be able to synchronize various actions such as fuel injection, control of the spark plugs, management of valve timing components, etc. This allows optimizing combustion efficiency and reducing fuel consumption and harmful emissions.

[0003] To this end, the crankshaft generally comprises a toothed wheel, the teeth of which are detected by the sensor. The toothed wheel generally comprises a set of teeth evenly distributed around its circumference, except for a reference portion (also called a gap) which does not include any teeth. By detecting the passage of a tooth in front of the sensor and counting the number of teeth that have passed starting from this gap, the position of the crankshaft in one rotation of 360° is known.

[0004] Now, one engine cycle corresponds to two complete rotations of the crankshaft, so determining the position of the engine based solely on the wheel of the crankshaft is not sufficient.

[0005] This information is therefore combined with information on the angular position of a camshaft which is driven in rotation by the crankshaft and which also comprises a toothed wheel, the teeth of which are detected by corresponding sensors.

[0006] One engine cycle corresponds to two 360° rotations of the crankshaft, while one engine cycle corresponds to only one 360° rotation of the camshaft. The toothed wheel of the camshaft therefore has a rotational asymmetry, which, when cross-referenced with the information about the crankshaft position, allows accurate deductions about the state of the engine cycle.

[0007] Therefore, each time the engine is started, the engine is synchronized when the crankshaft "play" is detected, combined with the detection of the camshaft wheel status.

[0008] refer to Figure 1 In the case of an engine with variable valve timing (also known as Variable Valve Timing, or VVT), steps may be taken to offset the angular position of the intake and / or exhaust camshafts relative to the crankshaft to induce exhaust gas recirculation in the cylinders, thereby reducing fuel consumption and reducing emissions. Figure 1In the diagram, the angular position of the crankshaft is shown in degrees on the abscissa (one rotation angle of the crankshaft corresponds to twice the corresponding rotation of the camshaft), and the displacement of the intake or exhaust valve is shown in millimeters on the ordinate. The displacement of the intake valves (curve A) and exhaust valves (curve B) controlled by the intake camshaft and exhaust camshaft, respectively, by default is shown in solid lines, and an offset of the camshaft angular position is shown in dashed lines (curve A' for the intake valves and curve B' for the exhaust valves), which serves to allow for an overlapping range between the opening phases of the intake and exhaust valves.

[0009] In order to improve the control performance of variable valve timing, it is known to position teeth on the toothed wheel of the camshaft that form a signature specific to each cylinder. For example, the toothed wheel of the camshaft of a four-cylinder engine may have four active edges each spaced 90° apart, such a passage of the sensor by each active edge corresponding to the same position of the piston in each respective cylinder.

[0010] Now, since the number of cylinders in an engine varies depending on the configuration of the engine, a variety of toothed wheels for camshafts are produced, including those for the same automobile manufacturer, which increases the production costs of these wheels.

[0011] Document US 2014 / 360254 discloses a toothed wheel of a camshaft comprising at least one tooth at each of the following positions of its circumference: 0°, 60°, 90°, 120°, 180°, 240°, 270° and 300°.

[0012] This makes it possible to obtain a single wheel that is compatible with both four-cylinder engines (since the information corresponding to each cylinder is provided by the 0°, 90°, 180° and 270° teeth) as well as three-cylinder and six-cylinder engines (information provided by the 0°CAM, 60°CAM, 120°CAM, 180°CAM, 240°CAM and 300°CAM teeth).

[0013] However, a toothed wheel of the camshaft comprising only these teeth is practical, since it has no rotational asymmetry and therefore does not allow the position in the engine cycle to be deduced by combining its position with that of the crankshaft. In order to overcome this drawback, and also to reduce the synchronization times, the document provides for the addition of a certain number of additional teeth in the other structures of the wheel.

[0014] Now, the addition of an excessively large number of teeth reduces the synchronization performance, since the amount of data (from the position sensor of the toothed wheel) to be processed increases.

[0015] Furthermore, if the toothed wheel of the camshaft has too great a number of teeth, there is a risk of desynchronization during a phase shift of the camshaft, since the signal detected by the position sensor of the camshaft when detecting a "backlash" of the crankshaft may differ from the signal detected when there is no phase shift. Summary of the invention

[0016] In view of the above, an object of the present invention is to propose a toothed wheel for a camshaft compatible with engines comprising three, four or six cylinders with variable valve timing.

[0017] Another object of the invention is to provide an improved synchronization performance.

[0018] Another object of the invention is to reduce the amount of processing required on the signal emitted by the position sensor of the toothed wheel in order to implement synchronization.

[0019] In this regard, a subject of the invention is a toothed wheel of a camshaft, forming a target for a camshaft rotation sensor, the toothed wheel comprising a plurality of teeth distributed over its circumference, the toothed wheel comprising: a first group of four teeth, each of which is spaced 90° apart; and a second group of six teeth, each of which is spaced 60° apart, the teeth in each group being distributed so that the wheel comprises at least two portions of its circumference, which at least two portions do not include an effective tooth edge over an angle of at least 35° and are spaced 180° apart, characterised in that the teeth in the first group of teeth and the second group of teeth are arranged so that the first group of teeth and the second group of teeth do not have any common teeth.

[0020] Advantageously, each tooth of the first set of teeth is offset from a tooth of the second set by an angle of between 10° and 20°.

[0021] In one embodiment, the toothed wheel comprises two first said portions which do not comprise an active tooth edge over an angle of at least 35° and are spaced 180° from each other.

[0022] Advantageously, the toothed wheel also comprises two second said portions which do not comprise an active tooth edge over an angle of at least 35° and are spaced 180° from each other and alternate with the two first portions.

[0023] Advantageously, the toothed wheel also comprises at least one additional tooth forming a mark for synchronizing the angular position of the camshaft with the angular position of the crankshaft.

[0024] In some embodiments, each tooth forms a rising edge and a falling edge, and two consecutive falling active edges or two consecutive rising active edges of the tooth are spaced at least 10° apart.

[0025] In one embodiment, the first teeth in the second set are spaced 15° from the first teeth in the first set, and the wheel further comprises at least two additional synchronizing teeth spaced 120° and 240° from the first teeth in the first set, respectively.

[0026] The invention also relates to a camshaft comprising a toothed wheel according to the above description.

[0027] Another subject of the invention is a three-, four- or six-cylinder internal combustion engine comprising at least one camshaft comprising a toothed wheel according to the above description.

[0028] Advantageously, the internal combustion engine has variable valve timing and further comprises:

[0029] - a crankshaft comprising a toothed wheel including a set of teeth regularly distributed over the circumference of the wheel and a reference space not including teeth,

[0030] - a crankshaft angular position sensor adapted to detect the presence of a tooth of the crankshaft toothed wheel,

[0031] - a camshaft angular position sensor adapted to detect the presence of teeth of a toothed wheel of the camshaft, and

[0032] - a processing unit adapted to receive position signals from the angular position sensor of the camshaft and from the angular position sensor of the crankshaft and to infer therefrom the state of the engine cycle,

[0033] - wherein the toothed wheel of the camshaft is positioned so that: the crankshaft angular position range in which the reference space of the toothed wheel of the crankshaft not including the teeth is located opposite the angular position sensor of the crankshaft is included in the crankshaft angular position range in which a portion of at least 35° of the toothed wheel of the camshaft not including the effective tooth edge is located opposite the angular position sensor of the camshaft.

[0034] In one embodiment, the engine comprises an intake camshaft and an exhaust camshaft, each comprising a toothed wheel according to the above description, the engine further comprising an angular position sensor for each of the intake camshaft and the exhaust camshaft, and the toothed wheel of the intake camshaft and the toothed wheel of the exhaust camshaft are positioned such that a reference space of the toothed wheel of the crankshaft not comprising teeth is located opposite the angular position sensor of the crankshaft over a range of crankshaft angular positions during which:

[0035] - is included in the crankshaft angular position range in which the part of the toothed wheel of the intake camshaft which does not include an active tooth edge is located opposite the respective angular position sensor, the angular position range extending in the clockwise direction by at least an additional 10°, that is to say by 45°=35°+10°, and

[0036] - is included in the following crankshaft angular position range, during which the part of the toothed wheel of the exhaust camshaft that does not include the effective tooth edge is located opposite the corresponding angular position sensor, and the angular position range extends in the counterclockwise direction by at least an additional 10°, that is to say by 45°=35°+10°.

[0037] The toothed wheel of the camshaft according to the invention comprises a first set of teeth spaced 90° apart, which makes it compatible with four-cylinder engines. A second set of teeth spaced 60° apart also makes it compatible with six-cylinder engines. The presence of two symmetrical parts that do not include an effective tooth edge and the angular range of at least 35° that it has makes it possible to ensure that, even in the case of a phase shift of the camshaft of an engine with variable valve timing, the effective edge for VVT control is not located in the "gap" area. In fact, by positioning the part that does not include teeth in relation to the "gap" of the crankshaft wheel, the toothed wheel according to the invention can be used in engines with variable valve timing, so that, even in the case of a camshaft offset, the "gap" of the crankshaft wheel always coincides with the part that does not include teeth. Since the engine position is based on an analysis of the crankshaft edge, the "gap" area produces greater inaccuracies.

[0038] Furthermore, the offset between the teeth of the first and second sets makes it possible to ensure the rotational asymmetry of the wheel without adding extra teeth and therefore allows the state of the engine cycle to be determined by combining the angular position information of the wheel with that of the crankshaft.

[0039] To reduce the synchronization time, one or two additional teeth may be added, spaced 150° and 240° apart from the first tooth in the first set, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other features and advantages of the present invention will become more apparent from reading the following description. This description is purely illustrative and must be read with reference to the accompanying drawings, in which:

[0041] [ Figure 1 ]: Already described Figure 1 shows the displacement of the intake and exhaust valves, which depends on the angular position of the camshaft associated therewith,

[0042] [ Figure 2 ]: Figure 2 An example of a toothed wheel of a camshaft according to an embodiment of the present invention is shown.

[0043] [ Figure 3 ]: Figure 3 Shown according to Figure 2 An example of synchronizing a toothed wheel with a toothed wheel of a camshaft according to an embodiment of the present invention,

[0044] [ Figure 4 ]: Figure 4 An example of an engine comprising a toothed wheel of a camshaft according to an embodiment of the invention is shown,

[0045] [ Figure 5 ]: Figure 5 An example of the positioning of the toothed wheel of the intake camshaft and the toothed wheel of the exhaust camshaft relative to the toothed wheel of the crankshaft is shown. DETAILED DESCRIPTION

[0046] In all that follows, angles in degrees measured on the toothed wheel of the camshaft or related to the angular position of the toothed wheel of the camshaft will be noted as "°CAM", and angles in degrees measured on the toothed wheel of the crankshaft or related to the angular position of the toothed wheel of the crankshaft will be noted as "°CRK". A rotation of 1°CAM corresponds to a rotation of 2°CRK.

[0047] refer to Figure 2 , a toothed wheel 1 of the camshaft will now be described which forms a target for a sensor 2 making it possible to determine the angular position of the camshaft.

[0048] The toothed wheel 1 has the general shape of a disk, with a plurality of teeth 10 on its circumference, each tooth having the general shape of a rectangle and forming successively a rising edge 11 and a falling edge 12 as it travels in front of the sensor 2. In order to allow good detection performance, two consecutive rising edges or two consecutive falling edges are advantageously at least 10° CAM apart, and the high level or the low level must have an angular opening of at least 5° CAM. The high level refers to the high part of the tooth, which separates the rising and falling edges of the tooth, and the low level refers to the part of the toothed wheel 1 that separates the falling and rising edges of two consecutive teeth.

[0049] The sensor 2 comprises a detection unit (eg, Hall effect unit type, magnetoresistive unit type, etc.) suitable for accurately detecting the rising edge or the falling edge of the tooth. The detected edge among the rising edge and the falling edge is called the effective edge.

[0050] The toothed wheel comprises a first set of teeth 13 comprising four teeth, each of which is spaced 90° CAM apart. In other words, the angular spacing between two rising edges or two falling edges of the set is 90°. Due to the spacing between the teeth, the teeth of this first set 13 form a reference for the four cylinders of a four-cylinder engine. For example, the toothed wheel 1 can advantageously be positioned on a camshaft of the engine so that the detection of the teeth of the set corresponds to the top dead center of the piston of the corresponding cylinder of the engine.

[0051] The toothed wheel also comprises a second set of teeth 14, which comprises six teeth, each of which is spaced 60° CAM apart. Similarly, this angular spacing of 60° CAM applies between two rising edges or two falling edges of the teeth of this set 14. Since the spacing between the teeth of this set 14 is 60°, each tooth of this set forms a reference for a corresponding cylinder of a six-cylinder engine. At the same time, this set 14 comprises a sub-set 15 of three teeth spaced 120° CAM apart, thus forming a reference for a cylinder of a three-cylinder engine.

[0052] The two sets 13 , 14 and the sub-set 15 of teeth thus render the toothed wheel 1 compatible with three-, four- or six-cylinder engines.

[0053] In order to be compatible with engines with variable valve timing (VVT), the toothed wheel 1 also has two first portions 16, which do not include effective tooth edges within an angular range of at least 35° CAM (e.g. equal to 45° CAM, which corresponds to a 90° CRK angle for the crankshaft), and the two first portions 16 are spaced 180° CAM apart. The first portions 16 can each cover an angular opening wider than 35° CAM, and in this case, the first portions 16 must include at least portions of 35° CAM, which are spaced 180° CAM apart.

[0054] As described in more detail below, and with reference to Figure 3 During the mounting of the toothed wheel on the camshaft, each first portion 16 not comprising an effective tooth edge is positioned at an angular position at which the "play" of the crankshaft wheel is detected and at the same time detected by the corresponding sensor.

[0055] exist Figure 3 On the left, the teeth of the crankshaft wheel (upper line - CRK) including two "clearance" areas G (not including teeth) are compared with the teeth of the toothed wheel of the camshaft (lower line - CAM, each number indicated by an arrow represents a crankshaft rotation angle value in °CRK, a camshaft rotation angle value in °CAM being equal to half the indicated value). The toothed wheel 1 of the camshaft is thus positioned so that the "clearance" area(s) G of the crankshaft correspond to the first portion 16 of the toothed wheel of the camshaft not including an effective tooth edge.

[0056] The amplitude of 35° CAM or more of the first portion 16 allows that even in the case of an angular offset of the camshaft for varying the opening angle area of ​​the intake or exhaust valves, the area of ​​the toothed wheel 1 detected by the sensor 2 while the crankshaft "play" is detected always does not include a valid tooth edge. Thus, the risk of inaccurate referencing associated with the detection of teeth while there is crankshaft "play" is avoided.

[0057] The presence of two first portions 16 spaced 180° CAM apart is due to the fact that one rotation of the camshaft corresponds to two rotations of the crankshaft and therefore the "backlash" of the crankshaft corresponds to two portions of the toothed wheel spaced 180° CAM apart.

[0058] Advantageously, the toothed wheel 1 may comprise, in addition to the two first portions 16, two second portions 20 which do not comprise active tooth edges over at least 35° CAM and which are spaced 180° from each other and which alternate with the two first portions 16. Thus, the first portions 16 and the second portions 20 are each spaced 90° CAM apart. This allows the toothed wheel 1 to be used with a wheel of a crankshaft comprising two "gap" zones for better synchronization.

[0059] Furthermore, the teeth of the first group 13 and the second group 14 are positioned so that there is always a spacing of at least 10° CAM between the teeth of the first group and the teeth of the second group, thereby not having any common teeth between the two groups. Preferably, each tooth of the first group is offset from a tooth of the second group by an angle of between 10° CAM and 20° CAM.

[0060] For example, in Figure 2 On the wheel shown, by fixing the 0° reference to the right of the wheel centre, the rising edges of the first set 13 of teeth are positioned at the following angles (in °CAM): 0°, 90°, 180°, 270°.

[0061] The rising edges of the teeth of the second set 14 are positioned at the following angles: 45°, 105°, 165°, 225°, 285° and 345°. Figure 3 This construction can also be seen in , where each arrow represents a tooth.

[0062] Thus, in this example, each tooth of the first set is spaced 15° from a tooth of the second set.

[0063] To ensure that there are no common teeth between the first group 13 and the second group 14, the first tooth of the second group 14 can be positioned at an angle between 10°CAM and 20°CAM offset from the first tooth of the first group 13 (for example, taking an angle of 0° as a reference), and then each tooth is positioned with reference to the first tooth of its corresponding group.

[0064] This construction allows obtaining a 360° CAM rotational asymmetry of the toothed wheel 1, that is, the profile of the teeth of any half of the toothed wheel is different from the profile of the teeth of the other half, and therefore allows the state of the engine cycle to be determined in conjunction with the angular position data of the crankshaft.

[0065] Advantageously, toothed wheel 1 may comprise one or more additional teeth 17 forming additional markings for improving the synchronization time of the engine, that is to say the time elapsed since the initialization of the rotation of the engine shaft and from which the state of the engine cycle is determined.

[0066] The additional tooth or teeth 17 are distinct from the teeth of the groups 13 and 14 and are also located outside the portions 16 and 20 which do not comprise an active tooth edge, where appropriate.

[0067] By adopting the above Figure 2 As a non-limiting example, the toothed wheel may include additional teeth 17, whose rising edges are located at 150° CAM and 240° CAM, respectively.

[0068] The positioning of the additional teeth 17 is determined to produce a 180° CAM and a 90° CAM rotational asymmetry: this means that if the target is cut into 2 equal parts, or 4 equal parts, these parts will not be equal.

[0069] Furthermore, the number of additional teeth 17 advantageously does not exceed five teeth, and more advantageously does not exceed three teeth, so as not to excessively increase the processing time associated with the acquisition of the signal representative of the passage of a tooth through the sensor 2 .

[0070] refer to Figure 4 , schematically shows an example of an internal combustion engine with variable valve timing comprising a toothed wheel according to the above description.

[0071] The engine M includes a crankshaft 9, which actuates at least one camshaft 91 to rotate through a timing belt 90, and the rotation of the camshaft 91 successively causes the intake valve and the exhaust valve 92 to open and close. For an engine with variable valve timing, it may further include a camshaft angle biasing device (not shown) for changing the valve opening time relative to the same position of the crankshaft. The maximum biasing angle is about 25°CAM (i.e. 50°CRK).

[0072] In one case not shown, the engine may include an intake camshaft 91 that controls the opening and closing of the intake valves and an exhaust camshaft 92 that controls the opening and closing of the exhaust valves.

[0073] The crankshaft 9 comprises a toothed wheel 93 comprising a set of teeth regularly distributed around its circumference, typically 36 or 60 teeth, except for one or two "gap" areas, which typically lack one or two teeth. Figure 3 and Figure 5 The example given in corresponds to 60 teeth, and two "gap" regions, each of which does not include two teeth.

[0074] The angular position sensor 94 of the crankshaft is positioned facing the toothed wheel 93 and is suitable for detecting the passage of each tooth of the wheel.

[0075] The toothed wheel 1 is mounted on the or each camshaft 91. A sensor 2 is located in front of the toothed wheel and is adapted to detect the passage of each tooth of the toothed wheel by detecting a rising or falling edge.

[0076] The engine also comprises a central processing unit 95 adapted to receive detection signals from sensors of the angular position of the crankshaft and of the camshaft and to deduce therefrom the state of the engine cycle at each instant.

[0077] As mentioned above Figure 3 As shown, the toothed wheel of the camshaft is positioned so that: the engine cycle range during which the reference space of the crankshaft toothed wheel not including teeth is located opposite the crankshaft angle position sensor 94 is included in the following engine cycle range, during which the portion of at least 35°CAM of the toothed wheel of the camshaft not including the effective tooth edge is located opposite the camshaft angle position sensor 2.

[0078] More advantageously, in the case where the engine comprises two camshafts, such as Figure 1 As shown, the offset of the intake camshaft and the exhaust camshaft is performed in opposite directions to make the common opening angle range of the exhaust valves closer.

[0079] The toothed wheels 1 corresponding to each camshaft are then advantageously positioned so that: over the entire angular offset range of each camshaft, the detection of the "gap" by the angular position sensor of the crankshaft corresponds to the detection of the portions 16, 20 of the two toothed wheels that do not include effective tooth edges, the two toothed wheels belonging respectively to the intake camshaft and the exhaust camshaft.

[0080] refer to Figure 5 , schematically showing the toothed wheel (CRK) of the crankshaft and the gears for the exhaust camshaft (CAMEX) and the intake camshaft (CAMIN) respectively. Figure 2 and Figure 3 The toothed wheel 1 of the camshaft has two first parts 16 and two second parts 20, which do not include effective tooth edges and each have an angular amplitude of at least 35° CAM. Figure 5 The degree indications on the lines CAMIN and CAMEX correspond to degrees of crankshaft rotation (°CRK).

[0081] In the default angular position of the intake camshaft (that is to say without the offset of the variable valve timing), the toothed wheel 1 of the intake camshaft is positioned so that: the crankshaft angle position range in which the "gap" area is located opposite the corresponding sensor is included in the crankshaft angle position range in which the portion 16 of the toothed wheel of the shaft that does not include an effective tooth edge is located opposite the corresponding sensor, and this range P extends in the clockwise direction over an additional at least 30° CRK relative to the detection range of the "gap" area. This additional range is Figure 5 As shown by the curly brackets, 30° CRK is relative to the rotation of the crankshaft, which is equivalent to 15° CAM of camshaft rotation.

[0082] Since the offset of the intake camshaft is in the counter-clockwise direction, the "gap" area, in the sense detected by the sensor, always corresponds to the portion of the toothed wheel of the exhaust camshaft that does not include an active tooth edge.

[0083] On the contrary, since the offset of the exhaust camshaft is carried out in the clockwise direction, the toothed wheel 1 of the exhaust camshaft is positioned so that: the crankshaft angle position range in which the "gap" area is located opposite the corresponding sensor is included in the following crankshaft angle position range, during which the part 16 of the toothed wheel of the shaft that does not include the effective tooth edge is located opposite the corresponding sensor, and this range P extends in the counterclockwise direction over an additional at least 30°CRK (of crankshaft rotation) (equivalent to 15°CAM of camshaft rotation).

[0084] The synchronization performance of an engine equipped with the above-mentioned toothed wheel is improved, since for a crankshaft toothed wheel comprising only one "gap", average synchronization is obtained after a rotation of less than 410°CRK, while for a crankshaft toothed wheel comprising two "gaps", average synchronization is obtained after a rotation of less than 230°CRK.

Claims

1. A toothed wheel (1) of a camshaft (91), forming a target for a rotation sensor (2) of the camshaft, the toothed wheel (1) comprising a plurality of teeth (10) distributed over its circumference, the toothed wheel (1) comprising a first group (13) of four teeth each spaced 90° apart; and a second group (14) of six teeth each spaced 60° apart, the teeth in each group being distributed so that the wheel comprises at least two portions of its circumference, the at least two portions not comprising an effective tooth edge over an angle of at least 35° and being spaced 180° apart, characterized in that The teeth of the first (13) set of teeth and the second (14) set of teeth are arranged such that the first (13) set of teeth and the second (14) set of teeth do not have any teeth in common.

2. The toothed wheel (1) of a camshaft according to claim 1, wherein: Each tooth in the first set (13) of teeth is offset from a tooth in the second set (14) by an angle between 10° and 20°.

3. The toothed wheel (1) of a camshaft according to claim 1 or 2, comprising two first portions (16) which do not include an active tooth edge over an angle of at least 35° and are spaced 180° from each other.

4. The toothed wheel (1) of the camshaft according to claim 3, further comprising two second portions (20), which do not include an effective tooth edge over an angle of at least 35°, are spaced 180° from each other, and alternate with the two first portions (16).

5. The toothed wheel (1) of the camshaft according to claim 1 or 2, further comprising at least one additional tooth (17), the at least one additional tooth (17) forming a mark for synchronizing the angular position of the camshaft with the angular position of the crankshaft.

6. The toothed wheel (1) of a camshaft according to claim 1 or 2, each tooth (10) forming a rising edge (11) and a falling edge (12), and wherein: Two consecutive effective falling edges (12) or two consecutive effective rising edges (11) of the tooth (10) are spaced at least 10 degrees apart.

7. The toothed wheel (1) of a camshaft according to claim 1 or 2, wherein: The first tooth in the second set (14) is spaced 15° from the first tooth in the first set (13), and the wheel further comprises at least two additional synchronizing teeth spaced 150° and 240° from the first tooth in the first set (13), respectively.

8. A camshaft (91) comprising a toothed wheel (1) of a camshaft according to any one of claims 1 to 7.

9. A three-, four- or six-cylinder internal combustion engine (M) comprising at least one camshaft (91) according to claim 8.

10. An internal combustion engine (M) according to claim 9, having variable valve timing and further comprising: - a crankshaft (9) comprising a toothed wheel (93) comprising a set of teeth regularly distributed over the circumference of said wheel and a reference space (G) comprising no teeth, - an angular position sensor (94) of the crankshaft, suitable for detecting the presence of teeth of the toothed wheel (93) of the crankshaft, - an angular position sensor of the camshaft, adapted to detect the presence of teeth (10) of the toothed wheel (1) of the camshaft (91), and a processing unit (95) adapted to receive position signals from said angular position sensor of said camshaft and said angular position sensor (94) of said crankshaft and to infer therefrom the state of an engine cycle, -Wherein, the toothed wheel (1) of the camshaft (91) is positioned so that: a crankshaft angular position range in which the reference space (G) of the toothed wheel of the crankshaft not including teeth is located opposite the angular position sensor (94) of the crankshaft is included in the following crankshaft angular position range, in which a portion of at least 35° of the toothed wheel (1) of the camshaft not including an effective tooth edge is located opposite the angular position sensor of the camshaft.

11. An internal combustion engine (M) according to claim 10, comprising an intake camshaft and an exhaust camshaft, each of which comprises a toothed wheel (CAMEX, CAMIN) according to any one of claims 1 to 7, the engine further comprising an angular position sensor for each of the intake camshaft and the exhaust camshaft, and the toothed wheel of the intake camshaft and the toothed wheel of the exhaust camshaft are positioned so that the reference space of the toothed wheel of the crankshaft not comprising teeth is located in a crankshaft angular position range opposite the angular position sensor of the crankshaft during which: - is included in a crankshaft angular position range in which a portion of the toothed wheel of the intake camshaft which does not include an active tooth edge is located opposite the respective angular position sensor, the crankshaft angular position range extending in the clockwise direction by at least an additional 10°, and - is included in the following crankshaft angle position range, during which the part of the toothed wheel of the exhaust camshaft that does not include an effective tooth edge is located opposite the corresponding angular position sensor, and the crankshaft angle position range extends in the counterclockwise direction by at least an additional 10°.

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