WO2017203156A1

WO2017203156A1 - Starter motor fitted with a pinion having at least one profiled tooth

Info

Publication number: WO2017203156A1
Application number: PCT/FR2017/051269
Authority: WO
Inventors: Jean-François OEUVRARD; Loïc LEMAIRE
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2016-05-25
Filing date: 2017-05-23
Publication date: 2017-11-30
Also published as: FR3051849A1; CN109154376A; EP3464950A1

Abstract

Starter motor for a motor vehicle, comprising a pinion (21) comprising a profiled tooth (203, 208) which comprises a driven face (205) and a driving face (204), said profiled tooth comprising a first portion and a second portion (210), termed irregular, extending axially from a second plane (P2), perpendicular to the X-axis, to a third plane (P3), perpendicular to the X-axis and situated at the other end of a tooth, and is delimited by the driven face and the driving face. It is envisaged that the cross-sections of the second portion (210) in the second plane (P2), the third plane (P3) and a fourth plane (P4) perpendicular to the X-axis situated between the second plane (P2) and the third plane (P3), each have a surface area, the surface area of the cross-section in the second plane (P2) being greater than the surface area of the cross-section in the fourth plane (P4) which is itself greater than the surface area of the cross-section in the third plane (P3), and that the cross-sections of the driven face (205) of the second portion in the second plane (P2), the third plane (P3) and the fourth plane (P4), respectively form ridges (304, 305, 306, 402) which each substantially comprise a shape of an involute of a circle of the X-axis formed from the director circle of the cylinder.

Description

STARTER WITH A PINION HAVING AT LEAST ONE PROFILED TOOTH

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a motor starter of a motor vehicle, said starter comprising a pinion adapted to be engaged with a ring of said heat engine and being provided with a profiled tooth.

BACKGROUND TECHNOLOGY

Motor vehicles comprising a heat engine also include a starting device of this engine, called starter.

FIG. 1 shows a starting device 1 according to the state of the art for an internal combustion engine of a motor vehicle.

This device 1 comprises, firstly, a rotor 2, also called armature, rotatable about an axis X, and secondly, a stator 3, also called inductor, placed around the rotor 2. This stator 3 has a yoke on which are fixed one or more pole pieces 4 for the introduction of an inductor coil 5.

The rotor 2 comprises a rotor body 7, and an armature winding 8 wound in notches of the rotor body 7.

This armature winding 8 forms, on either side of the rotor body 7, a front bun 9 and a rear bun 10.

The rotor 2 is provided, at the rear, with a collector 12 comprising a plurality of contact pieces electrically connected to the conductive elements, formed in the example in question by wires, of the armature winding 8.

A group of brushes 13 and 14 is provided for the power supply of the armature winding 8, one of the brushes 13 being connected to the ground of the device 1 and another of the brushes 14 being connected to a switch 17. The brushes are for example four in number.

The contactor 17 comprises a terminal 29 connected via an electrical connection element, in particular a wire 30, to a power supply of the vehicle, in particular a battery 26.

The brushes 13 and 14 rub on the collector 12 when the rotor 2 is rotating.

The starting device 1 further comprises a launcher 19 slidably mounted on a drive shaft 18 and drivable in rotation about the X axis by the rotor 2.

A gear reduction unit 20 may be interposed between the rotor 2 and the drive shaft 18, in a manner known per se.

The launcher 19 comprises a driving element formed by a pinion 21 and intended to engage on a drive member 33 of the combustion engine. This drive member is for example a ring gear.

The launcher 19 further comprises a freewheel 22 and a pulley washer 23 defining between them a groove 24 for receiving the end 25 of a fork 27. This fork 27 is made for example by molding a plastic material.

The fork 27 is actuated by the switch 17 to translate the launcher 19 relative to the drive shaft 18, along the X axis, between a first position in which the launcher 19 is disengaged from the ring gear 33 and a second position in which the launcher 19 drives the combustion engine via the pinion 21.

In order for the pinion 21 to drive the ring gear of the motor 33, the teeth of the pinion must after translation of the pinion and the launcher along the X axis reach a commitment position. According to this engagement position a tooth of the pinion is disposed between two teeth of the crown.

The pinion 21 then drives the ring gear 33 in a direction called positive direction which has the effect of causing when the pinion 21 rotates at a certain speed, the starting of the engine.

After starting the heat engine, the ring 33 continues to rotate in said positive direction. It then drives the pinion but not the rotor 2 thanks to the freewheel 22.

Indeed, the free wheel 22 is disposed between the rotor 2 and the pinion 21 to allow transmission of the torque of the rotor 2 to the pinion 21 and the ring 33 when it is driven in the positive direction by the pinion. On the contrary, when the ring gear 33 rotates in the positive direction and drives the pinion 21, the rotor 2 is not driven.

According to the state of the art, several types of start-up are defined according to the operating state of the heat engine.

More precisely, when stopping the engine, after idling, it goes through a phase of rapidly decreasing the speed of rotation, the start during this phase is called "Window 1", "window 1" or "W1" according to an Anglo-Saxon term well known to those skilled in the art. Subsequently, the motor goes through a sometimes called swinging phase in which its crown can rotate in a negative direction opposite to the positive direction of rotation mentioned above, the start during this phase is called "Window 2", "window 2" or "W2" according to an Anglo-Saxon term well known to those skilled in the art. When the engine is stopped, we speak of starting "window 0", "window 0" or "W0" according to an Anglo-Saxon term well known to those skilled in the art.

It is expected with the starters to make particular starts of the engine type W1. Depending on the type of start W1, the speed of rotation of the ring 33, decreasing, can reach a speed of the order of several hundred revolutions per minute, but not more than 800 revolutions per minute.

It is also provided with the starters to make, in particular, engine starts of the W2 type. Depending on the type of start W2, the rotational speed of the ring 33 may take a negative value.

According to the start W1 or W2, it is necessary that during the translation of the pinion teeth of the pinion can reach the engagement position mentioned above while the crown of the engine is still rotating. It happens that this commitment does not take place but on the contrary a tooth of the pinion taps against a tooth of the crown. This then causes a rebound of the pinion. The term firing window is defined which corresponds to the interval during which the translation of the pinion 21 will allow the teeth of the pinion to reach the engagement position. The firing window depends in particular on the speed of rotation of the crown 33, that of the pinion 21 and the circumferential width of the tooth of the pinion with respect to the distance between two teeth of the crown.

According to the state of the art, it is known to use a pinion whose teeth have a refined profile on the axial side to be introduced between two teeth of the crown. Such a pinion is illustrated in Figure 2. The pinion 21 comprises a base 200 having an outer periphery delimited by a cylinder 201 of axis X, for example a cylinder of revolution. In this case, it is a cylinder whose guide curve is a circle and whose generating line is the X axis, said generator line is perpendicular to the plane containing the director circle. In Figure 2, only illustrates the steering circle of the cylinder 201 for reasons of simplicity. The pinion 21 further comprises a set of teeth 202 extending radially from said outer periphery, the set of teeth comprises at least one profiled tooth 203 or 208. The profiled tooth 203 comprises a driving face 204 and a driven face. 205. The led and leading faces of the same tooth are separated by the top of the tooth. The leading face and the driven face are located on either side of a profiled tooth. They are defined relative to the crown 33. More specifically, the pinion 21 drives in the positive direction the ring 33 by a support of its driving face 204 on a tooth of the ring 33. On the contrary, when the heat engine is started, the ring gear 33 rotates in the positive direction and drives the pinion 21 by a support of one of its teeth on the driven face 205.

In other words, the driving face 204 is the one that comes into contact with the tooth of the crown when the tooth of the pinion is driving. On the contrary, the driven face 205 is the one that comes into contact with the tooth of the crown when the tooth of the pinion is driven.

The profiled tooth 203 comprises a first portion 209 said regular extending axially from a first plane P1 perpendicular to the axis X located at one end of a tooth to a second plane P2 perpendicular to the X axis , and is delimited by the driven face 205 and the driving face 204,

The profiled tooth 203 also comprises a second so-called irregular portion 210 extending axially from the second plane P2 perpendicular to the axis X to a third plane P3 perpendicular to the axis X situated at the other end of an tooth and is delimited by the led surface 205 and the driving face 204.

The irregular portion 210 comprises two visible chamfers 206 and 207 on the profiled tooth 203 or on the profiled tooth 208. The first chamfer 206 is formed in a first inclined plane of inclination of approximately 45 ° with respect to the plane comprising the radius and the X axis. The second chamfer is formed in a second section plane obtained by rotating the first section plane about the X axis.

The first chamfer 206 substantially reduces the circumferential width of the side of the tooth which enters first between two teeth of the crown. Thus the circumferential width of the tooth of the pinion relative to the distance between two teeth of the crown decreases and the firing window is increased. However, the pinion illustrated in FIG. 2 is not optimal. Indeed, the led face has disadvantages when starting W1 or W2.

Firstly, when the driven face of a tooth of the pinion will strike axially against a tooth of the ring gear in rotation, the gear tooth will on the one hand undergo an axial rebound force which causes ejection of the pinion. On the other hand, because of the 45 ° chamfer of the driven face, a tangential force is applied to the driven face of the tooth of the pinion. The pinion is then accelerated in rotation in addition to the rebound. This further increases the time to obtain penetration of the pinion in said engagement position.

On the other hand, for an axial penetration distance of the pinion 21 between two teeth of the given ring 33, the driving ratio is not constant. For example, for an axial penetration of 1 mm of the pinion between two teeth of the crown, by rotating the ring gear with the pinion, the driving ratio varies between 1 and 2. This implies that depending on the position of the teeth pinion and those of the crown, we can go from two points of contact between the pinion and the crown to a single point of contact. This passage from two points of contact to a point of contact will generate an impact which causes noise and compromises the durability of the pinion.

Moreover, with such a gear, the speed of the contact point or points varies according to their position. It can also cause noise.

It is known from patent application DE102010038443, sprocket teeth whose thickness is asymmetrical, in particular reduced or enlarged on one or both sides. However, such a tooth profile is only partially optimized from the point of view of noise.

There is therefore a need for a pinion that can overcome these disadvantages and in particular to reduce noise.

OBJECT OF THE INVENTION The invention aims to meet this need while remedying at least one of these disadvantages mentioned above. The subject of the invention is a starter for a motor vehicle, comprising:

a drive shaft comprising an axis X,

a pinion mounted on the drive shaft, the pinion comprising: a base having an outer periphery delimited by an X-axis cylinder, a set of teeth extending radially from said outer periphery, the set of teeth comprises at least one profiled tooth the profiled tooth comprising: a driven face and a driving face, a first portion said regular extending axially from a first plane perpendicular to the X axis located at one end of the tooth until a second plane perpendicular to the axis X, and delimited by the driven face and the driving face, a second so-called irregular portion extending axially from the second plane to a third plane perpendicular to the X axis located at the other end of the tooth and delimited by the led side and leading face.

According to a general characteristic of the invention, the sections of the second portion in the second plane, the third plane and a fourth plane perpendicular to the X axis situated between the second and the third plane, each have a surface, the surface of the section in the second plane being greater than the area of the section in the fourth plane which is itself greater than the area of the section in the third plane, and the sections of the second portion in the second plane, the third plane and the fourth plane, respectively form with the led side ridges which each comprise substantially a form of an involute of X-axis circle formed from the director circle of the cylinder. This makes it possible to obtain the advantage of a number of constant points of contact between the driven face and the crown during a start in W1 in particular. It can thus greatly reduce the noise of the starter in this type of startup. A significant reduction of the surface of the driven side tooth is allowed, which also makes it possible to increase the firing window.

For example, the cylinder defining the base of the pinion is a cylinder of revolution of X axis.

According to other characteristics taken separately or in combination, the at least one profiled tooth comprises a shape such that: the edge of the section of the face led in the fourth plane comprises a shape situated between two arcs formed from the inclination of -2 and +2 degrees, respectively, of an involute of X-axis circle formed from the director circle of the cylinder.

the edge of the section of the face led in the fourth plane comprises a shape having at least 3 points of the involute of X-axis circle formed from the director circle of the cylinder.

This gives a shape that is very faithful to a involute circle. All the advantages of the involute are thus obtained, namely a constant number of contact points as well as the constant speed of the contact points. This allows a reduction of noise.

the second portion comprises a portion whose section in the fourth plane has an area increased by less than 50% relative to the area of the section in the third plane, with a distance between the third and the fourth plane equal to 0.5 times the module of the toothing measured in the foreground. Thus characterized a led face profile having an optimum compromise between the sufficient mechanical strength of the teeth of the pinion, the speed of introduction and the noise level. For example, the section in the fourth plane may have an area increased by 34% relative to the area of the section in the third plane. the second portion comprises a portion delimited between the third plane and a fifth plane perpendicular to the X axis situated between the third and fourth planes, whose sections in planes perpendicular to the X axis each have the same surface value, said portion extending from the other end of the tooth.

- The part delimited between the third plane and a fifth perpendicular plane has a right tooth profile. If the tooth of the pinion must come to shock one of the teeth of the crown, then the tooth of the pinion will not be rotated. Only an axial force will be applied to it. Thus, the speed is substantially improved for the engagement of the pinion in the crown. in a projection of the vertex in a plane parallel to the axis X, the projection of the vertex of the tooth situated between the fifth plane and the second plane forms a line having a radius of curvature. This produces a radiated tooth. In other words, when moving axially from the fifth plane to the second plane, the top of the tooth follows a line having a radius of curvature.

for the planes perpendicular to the X axis of the second portion located between the fifth plane and the second plane, the intersection between the edge and the outer surface of the cylinder follow a constant pitch helix of axis X. We obtain thus a helical connection between the fifth and the second plane. The helical connection is favorable because it allows a smooth introduction with reduced noise.

the second portion comprises a portion delimited between the third plane and a sixth plane perpendicular to the X axis in which for planes perpendicular to the X axis, intersection between the edge and the outer surface of the cylinder follow a stepped propeller constant axis X. This produces a helical connection between the third and sixth plane. The helical connection is favorable because it allows a smooth introduction with reduced noise. It is therefore all the more favorable when it extends from the end of the tooth which is introduced into the crown. -The intersection, located between the third plane (P3) and a sixth plane (P6) perpendicular to the X axis, the edge and the outer surface of the cylinder in a constant pitch helix and, the intersection between the driven face and the outer surface of the cylinder between the sixth plane and the second plane forming a curve 602 each have a different pitch connected by a spoke.

- The constant pitch helix is configured so that the helix angle of the driven face is between 5 ° and 45 ° with the X axis in a plane perpendicular to the X axis. This results in a reduced tangential force when the pinion shoots a tooth of the crown. This improves the speed of engagement of the pinion in the crown. For example one can predict that the helix angle of the driven face is 5 ° with the X axis.

the projection in a plane parallel to the X axis of the vertex of the tooth situated between the sixth plane (P6) and the second plane (P2) forms a line having a radius of curvature. In other words: when moving axially from the sixth plane to the second plane the top of the tooth follows a line having a radius of curvature. This produces a radiated tooth.

the sixth plane coincides with the second plane so that for all the planes perpendicular to the X axis of the second portion, the intersections between the edge and the outer surface of the cylinder follow a constant pitch helix of X axis.

the sections of first portion said to be regular in planes perpendicular to the axis X each have the same surface. - The regular portion has a right tooth profile.

the teeth of the set of teeth are all profiled teeth. In a gear comprising a pinion and a heat engine crown, to be able to engrain the crown and the pinion must have the same module. Cutting the driven face of a tooth does not vary the gear module since the adjacent driven face is also cut so that the modulus equals the circumferential distance between the driven faces of the two adjacent teeth divided by the constant Pi remains the same.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative but not limiting of the invention.

Figure 1, already described, shows a view of a starter; Figure 2 already described, shows a pinion according to the state of the art; Figures 3a to 3d show a pinion according to a first embodiment of the invention; Figures 4a and 4b show a pinion according to a first embodiment of the invention; Figures 5a and 5b show a pinion according to a second embodiment of the invention; and Figures 6a and 6b show a pinion according to a third embodiment of the invention.

Identical, similar or similar elements retain the same reference from one figure to another.

DESCRIPTION OF EXAMPLES OF EMBODIMENT OF THE INVENTION FIG. 3a shows the pinion 21 according to a first embodiment of the invention. This pinion 21 differs in particular from that illustrated in Figure 2 from the profile of its led side 205 in the second portion 210, extending between the second plane P2 and third plane P3. As we can see it in Figure 3b, this profile is formed by three chamfers 301, 302 and 303.

As for the embodiment of Figure 2a, the cylinder 201 is for example a cylinder of revolution. In Figure 3a, as for Figure 2a, it is simply shown the cylinder 201 X axis, the steering circle for reasons of simplicity.

Figure 3b shows the pinion 21 according to a first variant of the first embodiment. In FIG. 3b are illustrated in the form of a straight line, in addition to the first plane, the second plane, the third plane respectively P1, P2, P3, already described, a fourth plane P4 and a sixth plane P6. The plane P4 corresponds to any plane which is situated between the second P2 and the third plane P3. The plane P6 is located on the second so-called irregular portion 210 between the second plane P2 and the third plane P3. It is for example confused with the plane P2 as illustrated in Figure 3b All planes P1, P2, P3, P4 and P6 are perpendicular to the axis X and are therefore parallel to each other.

In the remainder of the description, the surface of the section of the second portion 210 in a plane Px, S (Px) is noted. Thus, for example, the area of the section of the second portion 210 in the plane P2 is S (P2), the area of the section of the second portion 210 in the plane P3 is S (P3), the area of the section of the second portion 210 in the plane P4 is S (P4).

On the side of the driven face 205, the three chamfers 301, 302 and 303 start from the plane P3 perpendicular to the axis X situated at one end of the tooth and extend as far as the plane P2 perpendicular to the axis X. Each chamfers extend at an angle to the X axis from the end of the tooth such that: S (P3) <S (P4) <S (P2).

The section of the driven surface 205 in the plane P2 forms an edge 304, the section of the driven face 205 in the plane P4 forms an edge 305 and the section of the led face 205 in the plane P4 forms an edge 306. Each of the edges 304, 305 and 306 has substantially a shape of an involute of X-axis circle formed from the director circle of the cylinder 201 starting from the points 01, 02 and 03.

The points 01, 02 and 03 are the intersections between the outer surface of the cylinder 201 and the edges 304, 305, 306 respectively. For example, these intersections follow a constant pitch helix on the outer surface of the cylinder 201. In other words, the second portion comprises a portion delimited between the third plane P3 and the sixth plane P6 perpendicular to the axis X in which for planes perpendicular to the axis X, the intersections between the edge and the surface external cylinder 201 follow a constant pitch propeller.

When, as shown in FIG. 3b, the sixth plane P6 coincides with the second plane P2, for all the planes perpendicular to the axis X of the second portion, the intersections between the edge and the outer surface of the cylinder follow. a constant pitch propeller.

For example, the constant pitch helix is configured so that the helix angle of the driven face is 5 ° with the X axis.

For example, as illustrated in FIG. 3b, the edge 305 of the section of the driven face 205 in the fourth plane comprises a shape having at least 3 points of the X-axis involute formed from the direction circle of the cylinder. Specifically, the X-axis involute formed from the center circle from point 02 is tangent to edge 305 at points 307, 308 and 309. Points 307, 308 and 309 are points belonging to the chamfers. 301, 302 and 303 respectively in the fourth plane P4.

For example, one can choose the angle of the three chamfers 301, 302 and 303 with the axis X so that the surface S (P4) is increased by less than 50% with respect to the surface S (P3), the distance axial between the third P3 and the fourth plane P4 being equal to half the module of the toothing measured in the first plane P1. For example, the area S (P4) can be increased by 34% relative to the area S (P3). In the plane P1, the module is measured as the pitch pitch which is obtained from the circumferential distance between the driven faces of two adjacent teeth, divided by the well-known constant Pi, also denoted π and equal to approximately 3.14. In other words, the second portion 210 comprises a portion whose section in the fourth plane has an area increased by less than 50% relative to the area of the section in the third plane, with a distance between the third and the fourth plane equal to 0.5 times the modulus of the toothing measured in the first plane P1.

FIG. 3c illustrates a second variant of the first embodiment of pinion 21. This second variant differs from the first variant in that the edge 305 is between two arcs 309 and 310. The arc 309 corresponds to the involute of X-axis circle formed from the director circle of the cylinder 201 while leaving point O2 after rotation of -2 °. Similarly, the arc 310 corresponds to the involute of X-axis circle formed from the director circle of the cylinder 201 starting from the point O2 after rotation of + 2 °. In other words, the edge 305 of the section of the driven face 205 in the fourth plane P4 comprises a shape situated between two arcs formed from the inclination of -2 and +2 degrees respectively, of an involute an X-axis circle formed from the director circle of the cylinder 201.

Figure 3d illustrates the first embodiment according to a view from above. FIG. 3d shows, in addition to the three chamfers 301, 302 and 303, the area of the section of the second portion in the third plane S (P3).

For the first embodiment illustrated in FIGS. 3a, 3b, 3c and 3d, the sections of the driven face 205 of the first portion of the second portion 210 in planes perpendicular to the X axis located between the planes P2 and P3 have substantially a form of involute of circle obtained from the director circle of the cylinder 201. In addition, the intersection between the driven surface 205 and the outer surface of the cylinder 201 between the plane P3 and the plane P2 forms a constant pitch helix. It is therefore a helical connection between the section in the plane P3 and the section in the plane P2. Figures 4a and 4b show the pinion 21 according to a second embodiment of the invention. This pinion 21 differs from the first embodiment from the profile of its driven surface 205 in the second portion 210 extending between the second plane P2 and third plane P3. As for the embodiment of Figure 2a, the cylinder 201 is, for example, a cylinder of revolution. In Figure 4a, as for Figure 2a, it is simply shown the X-axis cylinder 201 the steering circle for reasons of simplicity.

In FIG. 4b are illustrated in the form of a straight line, in addition to the planes P1, P2, P3, P4 already described, a plane P5. The plane P5 is located on the second so-called irregular portion between the second plane P2 and the third plane P3. All planes P1, P2, P3, P4 and P5 are perpendicular to the X axis and are therefore parallel to each other.

The second portion 210 comprises a first portion delimited between the third plane P3 and the fifth plane P5 whose sections in planes perpendicular to the X axis each have the same surface. For example, as illustrated in Figure 4b, the first portion defined between the third plane P3 and the fifth plane P5 has a right tooth profile.

In any event, the sections of the driven face 205 of the first portion of the second portion 210 in planes perpendicular to the X axis have a form of involute of a circle obtained from the director circle of the cylinder 201. In addition, this first part being delimited by the plane P3 and plane P5, it therefore extends from the end of the tooth.

The second portion 210 further comprises a second portion delimited between the fifth plane P5 and the second plane P2. The intersection between the driven surface 205 and the outer surface of the cylinder 201 between the plane P5 and the plane P2 forms the curve 401. It is on this curve 401 that will be intersections between the edges of the face carried in the planes perpendicular to the X axis of the second part and the outer surface of the cylinder 201. For example, the curve 401 is in the form of a constant pitch helix. In this case, it is a helical connection between the section in the plane P5 and the section in the plane P2. In other words, in the planes perpendicular to the X axis of the second portion 210 located between the fifth plane and the second plane, the intersections between the edge and the outer surface of the cylinder follow a constant pitch helix. In any event, the sections of the driven face 205 of the first portion of the second portion 210 in planes perpendicular to the X axis have substantially a form of involute of circle obtained from the director circle of the cylinder 201.

The plane P4 is any plane situated between the plane P3 and plane P2 for which S (P3) <S (P4) <S (P2). The plane P4 can not be located between the planes P3 and P5 but between the planes P5 and P2. In any case, the driven surface 205 of the second portion in the plane P4 forms an edge which substantially comprises a shape of an involute of X-axis circle formed from the cylinder director circle. As illustrated in FIG. 4b, for the plane P4 located between the planes P5 and P2, the section of the driven face 205 in the plane P4 forms an edge 402 which is derived from the point O2. The point O2 is at the intersection between the edge 402 and the outer surface of the cylinder 201 and is located on the curve 401. The edge 402 has substantially the shape of an X-axis circle involute formed from the director circle of the cylinder 201 from the point O2.

On the other hand, it is possible to choose the position of the plane P5 and the helix angle of the helical connection between the section in the plane P5 and the section in the plane P2 so that the section in the fourth plane has an area increased by less than by 50% with respect to the surface of the section in the third plane, the axial distance between the third P3 and the fourth plane P4 being equal to half of the modulus of the toothing measured in the first plane P1. For example, the area S (P4) can be increased by 34% relative to the area S (P3).

Figures 5a and 5b illustrate the pinion 21 according to a third embodiment. This pinion 21 differs from that of the second embodiment from the profile of the driven surface 205 in the second portion 210, extending between the second plane P2 and fifth plane P3. As we can be seen in Figures 5a and 5b, when moving axially from the fifth plane to the second plane the top of the tooth follows a line having a radius of curvature.

In any case, for any plane P4 situated between the planes P5 and P2 of the second portion 210, the section of the driven face 205 of the second portion has substantially a form of involute of a circle obtained from the director circle of the cylinder 201.

Figures 6a and 6b illustrate a pinion 21 according to a fourth embodiment. This pinion 21 differs from that of the first embodiment from part including the positioning of the plane P6 which is no longer confused with the plane P2. The second portion 210 thus forms two parts, a first portion located between the planes P3 and P6 and a second portion between the planes P6 and P2.

For the first part, the intersection between the driven face 205 and the outer surface of the cylinder 201 between the plane P3 and the plane P6 forms the curve 601. It is on this curve 601 that the intersections between the edges of the driven face 205 in the planes perpendicular to the X axis of the first part and the outer surface of the cylinder 201 will be found. For example, the curve 601 is in the form of a constant pitch helix. In this case, it is a helical connection between the section in the plane P3 and the section in the plane P6. For example, the constant pitch helix is configured so that the helix angle of the driven face 205 is 5 ° with the X axis.

In other words, in the planes perpendicular to the X axis of the second portion located between the third plane P3 and the sixth plane P6, the intersections between the edge and the outer surface of the cylinder follow a constant pitch helix.

In any case, for any plane P4 situated between the planes P3 and P6 of the second portion 210, the section of the driven face 205 of the first portion has a shape of involute of a circle obtained from the director circle of the cylinder 201 starting from points on curve 601. For example, it is possible to choose the helix angle of the driven surface 205 of the first part so that the section in the fourth plane P4 located in the first part has an area increased by less than 50% with respect to the surface. of the section in the third plane, the axial distance between the third P3 and the fourth plane P4 being equal to half the module of the toothing measured in the first plane P1. For example, the area S (P4) can be increased by 34% relative to the area S (P3).

For the second part, the intersection between the driven face 205 and the outer surface of the cylinder 201 between the plane P6 and the plane P2 forms the curve 602. It is on this curve 602 that will be intersections between the edges of the driven surface 205 in the planes perpendicular to the X axis of the second portion and the outer surface of the cylinder 201. For example, the curve 602 has the shape of a constant pitch helix. In this case, it is a helical connection between the section in the plane P6 and the section in the plane P2. For example, the constant pitch helix is configured so that the helix angle of the driven face 205 of the second portion is greater than the helix angle of the driven face 205 of the first portion.

As can be seen in Figure 6b, when moving axially from the sixth plane P6 to the second plane P2, the top of the tooth follows a line having a radius of curvature.

For any plane P4 located between the planes P6 and P2 of the second portion 210, the section of the driven face 205 of the second portion has a shape of involute of a circle obtained from the director circle of the cylinder 201 from the points located on the curve 602. For example, one can choose the helix angle of the driven face 205 of the first part and the helix angle of the driven face 205 of the second part so that the section in the fourth P4 plane in the second part has an area increased by less than 50% with respect to the area of the section in the third plane, the axial distance between the third P3 and the fourth plane P4 being equal to half of the module of the teeth measured in the first plane P1. For example, the area S (P4) can be increased by 34% relative to the area S (P3). Note that for all embodiments of Figures 3a, 3b, 3c, 3d, 4a, 4b, 5a, 5b, 6a, 6b in a gear comprising a pinion 21 and a ring 33, to be able to grain the crown and the pinion must have the same module. Cutting the led side of a tooth does not vary the pinion modulus since the adjacent led face is also trimmed so that the modulus equals the circumferential distance between the driven faces of the two adjacent teeth divided by the constant Pi remains the same.

The pinions of the embodiments illustrated in FIGS. 3a, 3b, 3c, 3d, 4a, 4b, 5a, 5b, 6a, 6b can be used for example in a starter as described in FIG.

Claims

1. Starter for a motor vehicle, comprising: a drive shaft (18) comprising an X axis, a pinion (21) mounted on the drive shaft, the pinion comprising: a base (200) having an outer periphery delimited by a X-axis cylinder (210), a set of teeth (202) extending radially from said outer periphery, the set of teeth comprises at least one profiled tooth, the profiled tooth (203, 208) comprising: a driven face (205) and a driving face (204), a first portion (209) said regular extending axially from a first plane (P1) perpendicular to the X axis located at one end of the tooth until at a second plane (P2) perpendicular to the axis X, and delimited by the driven face and the driving face, a second portion (210) said irregularly extending axially from the second plane (P2) to a third perpendicular plane (P3) to the X axis located at the other end of the tooth and deli formed by the driven face and driving face, characterized in that the sections of the second portion (210) in the second plane (P2), the third plane (P3) and a fourth plane (P4) perpendicular to the X axis located between the second (P2) and the third plane (P3), each have a surface, the surface of the section in the second plane (P2) being greater than the surface of the section in the fourth plane (P4) which is itself greater than the area of the section in the third plane (P3), and in that the sections of the second portion in the second plane (P2), the third plane (P3) and the fourth plane (P4) respectively form with the driven face edges (304, 305, 306, 402). each substantially comprising a shape of an X-axis involute formed from the cylinder director circle.

2. A starter according to claim 1, wherein the edge (305) of the section of the face led in the fourth plane (P4) comprises a shape located between two arcs (309, 310) formed from the inclination of -2 and +2 degrees, respectively, of an involute of X-axis circle formed from the director circle of the cylinder (201).

The starter according to claim 1 or 2, wherein the edge (305) of the section of the driven face (205) in the fourth plane (P4) comprises a shape having at least 3 points (307, 308, 309). the X-axis circle involute formed from the director circle of the cylinder (201).

4. Starter according to one of claims 1 to 3, wherein the second portion (210) comprises a portion whose section in the fourth plane (P4) has an area increased by less than 50% relative to the surface of the section in the third plane, with a distance between the third and the fourth plane equal to 0.5 times the module of the toothing measured in the first plane (P1).

5. Starter according to one of claims 1 to 3, wherein the second portion (210) comprises a portion delimited between the third plane and a fifth plane perpendicular (P5) to the X axis located between the third and fourth planes ( P3, P4), whose sections in planes perpendicular to the X axis each have the same surface value, said portion extends from the other end of the tooth.

6. Starter according to the preceding claim, wherein the portion defined between the third plane (P3) and a fifth plane (P5) perpendicular has a right tooth profile.

7. A starter according to claim 5 or 6, wherein in a projection of the vertex in a plane parallel to the axis X, the projection of the crown of the tooth situated between the fifth plane and the second plane forms a line having a radius of curvature.

8. Starter according to claim 5 or 6, wherein for the planes perpendicular to the X axis of the second portion between the fifth plane (P5) and the second plane (P2), Γ intersection between the edge and the surface external cylinder follow a constant pitch propeller X axis.

9. Starter according to one of claims 1 to 3, wherein the second portion (210) comprises a portion defined between the third plane (P3) and a sixth plane (P6) perpendicular to the axis X in which for plans perpendicular to the X axis, the intersection (601) between the edge and the outer surface of the cylinder (201) follow a constant pitch helix of axis X.

10. Starter according to the preceding claim, wherein the constant pitch helix is configured so that the helix angle of the driven face (205) is between 5 ° and 45 ° with the X axis in a perpendicular plane. to the X axis.

1 1. Starter according to claim 9 or 10, wherein the projection in a plane parallel to the X axis of the vertex of the tooth located between the sixth plane

(P6) and the second plane (P2) forms a line having a radius of curvature.

12. Starter according to claim 9 or 10, wherein the sixth plane is coincident with the second plane so that for all the planes perpendicular to the X axis of the second portion, Γ intersection between the edge and the surface outer cylinder (201) forms a helix with constant pitch of X axis.

13. Starter according to one of the preceding claims wherein the sections of the first portion (209) said regular in planes perpendicular to the X axis each have the same surface.

14. Starter according to the preceding claim, wherein the regular portion (209) has a right tooth profile.

15. Starter according to one of the preceding claims wherein the teeth of the set of teeth (202) are all profiled teeth.