FR3081939A1 - LAUNCHER FOR MOTOR VEHICLE STARTER - Google Patents

Abstract

1. The present invention relates to a launcher (3) for a starter (1) of a motor vehicle, capable of turning about an axis, comprising: - a pinion body (23) having a groove (32), - a pinion ( 5) able to mesh with a crown of a heat engine, the pinion being slidably mounted along an axis (X) on the pinion body (23), the pinion having an abutment position relative to the pinion body, - at least one elastic member (21) mounted axially between the pinion and the pinion body to return the pinion to the stop position, - a metal circlip (33) having a fiber structure, the circlip being mounted in the groove, the circlip being in plan contact with the groove and the pinion in the stop position of the pinion relative to the pinion body.

Description

LAUNCHER FOR A MOTOR VEHICLE STARTER

The present invention relates to the field of starters and in particular starters for motor vehicles.

A starter comprises a launcher on which is mounted a pinion intended to mesh with a crown of a heat engine, an electric motor intended to drive the pinion in rotation and a contactor intended to move the launcher in axial translation via a fork for allow movement of the pinion towards the crown.

It is known to have a pinion in two parts. One of the two parts has teeth mounted capable of coming into contact with the teeth of the crown and is slidably mounted on the other of the two parts which transmits the torque of the electric motor. An axial spring is mounted axially between these two parts to push the part having the teeth in the direction of the crown.

The spring makes it possible to apply a stress to the pinion, when the latter begins to mesh with the crown of the heat engine, making it possible to improve the entry of the pinion into the crown and therefore to optimize the gear of the pinion. with the crown. This therefore reduces the time and noise of the gear and also reduces the wear on the crown and the pinion.

An axial stop is necessary to limit the sliding movement of the two parts of the pinion with respect to one another in the direction of the crown.

It has become apparent that conventional axial stops do not make it possible to comply with the current specifications defined by automobile manufacturers, in particular in fatigue resistance.

If such a part is made to rupture, the rotating pinion is then axially free and causes significant damage.

There is therefore a need for the reliability of a launcher having a pinion in two parts.

To this end, the present invention relates to a launcher for a motor vehicle starter, capable of turning around an axis, comprising:

- a pinion body having a groove,

a pinion capable of meshing with a crown of a heat engine, the pinion being slidably mounted along the axis on the pinion body, the pinion having an abutment position relative to the pinion body,

- at least one elastic member mounted axially between the pinion and the pinion body to return the pinion to the stop position,

- a metal circlip having a fiber structure, the circlip being mounted in the groove, the circlip being in plan contact with the groove and the pinion in the pinion stop position relative to the pinion body, characterized in that the fibers of the fiber structure are substantially all oriented in a circumferential direction, and that the radial thickness of the circlip is substantially constant over the whole of its periphery.

Such a launcher has a substantial gain in fatigue resistance compared to launchers fitted with conventional circlips.

The circlip does not have a zone of stress concentrations linked, for example, to sudden variations in thickness along the periphery.

The flat surfaces allow a uniform distribution of the forces due to the abutment of the pinion on the circlip and on the pinion body.

The drawing of the circlip gives better mechanical resistance to repeated impacts from the pinion. Random distribution of the fibers in a conventional circlip leads to a reduction in fatigue strength leading to premature rupture.

Such a circlip makes it possible to limit the number of parts for performing the stop function in translation.

According to one aspect of the invention, the circlip can have a homogeneous surface condition at the level of the plane contacts with the groove and the pinion. The roughness can be constant on all the contact surfaces of the circlip with the groove and the pinion. The areas of contact with the groove and the pinion are thus devoid of tearing zones which concentrate the stresses.

According to one aspect of the invention, the circlip can have at least one blunt edge. In particular, the circlip has at least three blunt circumferential extension edges. In particular again, all the edges of the circumferential extension circlip are blunt. The absence of abrupt transition, especially at right angles, avoids areas of stress concentration.

The edges can be rounded between two successive faces of the circlip. The radius of the rounding can be between 0.1 mm and 0.3 mm, preferably between 0.15 mm and 0.2 mm.

According to another aspect of the invention, the circlip has a substantially rectangular section along its periphery. This rectangular section can be constant along its periphery.

This rectangular section can be seen in any plane crossing the circlip and including the axis. The axis of rotation of the launcher is the axis of revolution of the circlip.

According to another aspect of the invention, the circlip can have an opening of length less than 2 mm, preferably less than 1 mm in the free state.

This length is a minimum distance between two points of the circlip along an orthoradial axis.

The circlip can therefore have a form of ring with rectangular section open locally.

The circlip may have cut edges only at the opening. The absence of cut edges on the useful surfaces of the circlip improves its fatigue resistance.

According to another aspect of the invention, the circlip may have a first planar contact face and a second planar contact face substantially parallel to one another, the faces being in contact, respectively with the groove and the pinion when the pinion is in position. stop.

The normal to these first and second faces can form an angle less than 7 °, preferably 2 °, more preferably 1 °.

According to another aspect of the invention, the circlip can have a ratio: contact surface with the pinion body. , _

----------- -------------—; -------- between 1 and 2.5, preferably between 1.7 and 2 3.

contact surface with the pinion

A circlip with such a ratio is significantly smaller than conventional circlips. A conventional circlip with such proportions would not meet the expected fatigue performance.

A circlip exhibiting the structural characteristics set out above and having such a ratio makes it possible to substantially improve the resistance to fatigue.

The contact surface with the pinion body can be maximized because the circlip has a constant radial thickness over its entire periphery. The improvement of the external qualities of the circlip (circumferentially oriented fibers) and of its external structure (constant section, constant thickness, blunt edges) make it possible to reduce the contact surface with the pinion.

According to another aspect of the invention, the radial thickness of the circlip may be between 2 mm and 3 mm, preferably between 2.1 mm and 2.3 mm, preferably be 2.24 mm.

The circlip can have a maximum radius of between 9 mm and 10 mm. The circlip can have a minimum radius of between 6.5 mm and 7.5 mm.

According to another aspect of the invention, the circlip can have an axial thickness of between 1.0 mm and 1.5 mm, preferably 1.2 mm.

According to one aspect of the invention, the circlip is made of quality steel with a high content of unalloyed carbon, for example comprising at least 0.5% carbon. Such a steel presents a good technical and economic compromise and meets the mechanical requirements. We can nevertheless consider more efficient steels.

According to another aspect of the invention, the circlip can be obtained by winding a round wire previously flattened. The circlip can be obtained by stamping to give it a rectangular section and by rolling to give it its shape of revolution.

Such a process is economical in terms of raw material because the quantity of scrap is limited. Such a method makes it possible to obtain the surface condition described above of the areas of contact of the circlip with the groove and with the pinion. This surface condition is more homogeneous, in particular on the radially inner and outer edges.

The circlip can then be cut to the desired length. This cut forms the aforementioned opening so that there are traces of tooling only at the opening.

The pinion body may have a shoulder. The elastic member can be mounted between the pinion and the shoulder. The elastic member is compressed when the pinion is moved away from its stop position.

The elastic member can be mounted prestressed so that in the pinion stop position, it exerts a load of between 40 N and 80 N, preferably between 55 N and 65 N.

The pinion can have a stroke of between 2 mm and 6 mm, in particular equal to 4 mm.

The elastic member may have a stiffness of between 2,000 N / m and 10,000 N / m. The elastic member can be a spring, in particular a helical spring. The spring has a number of turns between two and four.

The present invention also relates to a motor vehicle starter comprising a launcher as described above.

The launcher has a geared position in which the pinion is engaged with the crown of the heat engine and a rear position in which the pinion is not engaged with the crown.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and without limitation. , with reference to the appended figures, in which:

FIG. 1 represents a view in longitudinal section of a starter according to an embodiment of the present invention,

FIG. 2 represents, schematically and partially, a view in longitudinal section of a launcher capable of equipping the starter of FIG. 1,

FIG. 3 represents, diagrammatically and partially, a circlip capable of equipping the launcher of FIG. 2,

FIG. 4 represents a section of the circlip of FIG. 3, and

- Figure 5 shows a micrograph of the circlip obtained after chemical attack.

In the following description, the "front part" of the launcher or starter corresponds to the part located on the side of the crown of a heat engine and the "rear part" corresponds to the part opposite to the crown. Thus, a “forward” direction corresponds to a direction towards the “front part” of the launcher or of the starter.

figures

Figure 1 shows a diagram of a starter 1 for rotating a crown 6 of a heat engine. The starter 1 comprises a launcher 3, an electric motor 7 intended to drive the launcher 3 in rotation about an axis X, a contactor 13 intended to drive the launcher 3 in translation by means of a fork 21. The electric motor 7 comprises a cylinder head 9, a rotor and a stator.

The contactor 13 comprises at least one coil 15 allowing, when powered, to move a mobile part of a magnetic core or mobile core 17 in translation towards a fixed part 16 of the magnetic core inside a gap 19 In general, two coils are used, a take-up reel and a holding reel, the call reel being used in addition to the holding reel to move the movable core 17, then when the air gap 19 is closed, the holding coil is used alone to hold the movable core 17 close to the fixed part 16 of the magnetic core. In the following description, we will limit ourselves to designating a coil 15 (which can therefore comprise several coils).

The contactor 13 also comprises a rod 18 movable in translation relative to the mobile core 17 of the contactor 13. A spring called a tooth-tooth spring 20 is positioned at the interface between the mobile core 17 and the rod 18. The rod 18 is therefore movable relative to the movable core between a first position in which the tooth-tooth spring 20 is relaxed and a second position in which the tooth-tooth spring 20 is compressed. The toothed spring 20 has for example a stiffness of about 11 N / mm and a length at rest of the order of 22 mm and is mounted with a preload of about 45 N. The contactor 13 may also include other springs configured to return the movable core 17 to the initial position, that is to say at a distance from the fixed part 16 when the coil 15 is no longer supplied.

The rod 18 is attached to a first end of the fork 21. The connection between the rod 18 and the fork 21 can be made by any suitable means for transmitting the force or the torque between the fork 21 and the rod 18.

The fork 21 is configured to tilt around an axis of rotation located at its central part. The fork 21 also includes a second end, opposite its first end relative to the central part, intended to come into contact with the launcher 3 to allow axial movement of the launcher 3 when the coil 15 of the contactor is supplied.

The lever arm of the fork 21 has for example a ratio of a distance between the first end and the axis of rotation to the distance between the second end and the axis of rotation equal to 1.5. The stroke of the starter 3 is therefore approximately 1.5 times the stroke of the rod 18 of the contactor 13.

The launcher 3 is driven in rotation by the electric motor 7 located at the rear of the launcher 3. The rotation drive of the launcher 3 is, here, carried out via a reduction crown 11 arranged at the front end of the cylinder head 9.

The launcher 3 is therefore mobile in rotation and in translation. The rotary drive is carried out by the electric motor 7 and the translational drive is carried out by the contactor 13 via the fork 21.

The launcher 3 is shown in more detail in FIG. 2. The launcher 3 comprises a pinion body 23 movably mounted in rotation and in axial translation on a shaft 25 via bearings 27, here needle bearings. The shaft 25 extends along the axis X.

The launcher 3 also comprises a pinion 5 able to mesh with the crown 6. The pinion 5 is slidably mounted along the axis X on the pinion body, the pinion having a stop position relative to the pinion body 23.

The pinion 5 is mounted on the front part of the pinion body 23. The front part of the pinion body 23 is therefore the part located on the side of the crown 6 and the rear part of the pinion body 23 is the part of the pinion body. 23 located on the side of the electric motor 7.

The pinion body 23 has a groove 32 disposed in front of the pinion 5 in which is mounted a metal circlip 33 forming an axial stop of the pinion relative to the pinion body.

The launcher therefore has a geared position in which the pinion 5 is engaged with the crown 6 and a rear position, as illustrated in FIG. 1, in which the pinion 5 is not engaged with the crown 6. The pinion 5 has a stroke of between 8 mm and 14 mm.

In addition, the pinion body is itself movable in axial translation relative to the shaft 25. The starter 3 has a non-geared position in which the pinion is not engaged with the crown 6 and a geared position in which the pinion is in engagement with the crown 6. In the geared position, the pinion body 23 is supported on a stop 38 disposed on a front part of the shaft 25.

The pinion body has a shoulder 29 disposed behind the pinion 5. An elastic member 31, for example a helical spring or an elastomer, is disposed around the axis X and bears on the one hand against the shoulder 29 of the pinion body 23 and on the other hand against the pinion 5 to return the pinion to the stop position. The elastic member 31 is thus compressed when the pinion is moved away from its stop position.

Thus, in the stop position, the pinion 5 is in abutment against the circlip 33, the pinion 5 is constrained by the elastic member 31 against said circlip 33. The elastic member 31 allows, in compression, a displacement in translation of the pinion body 23 when the pinion 5 is in tooth-to-tooth position with the motor crown 6, that is to say when the teeth of the pinion 5 are in axial contact with the teeth of the motor crown 6 without it there is a gear between the two.

Furthermore, the shoulder 29 comprises, for example, a radial projection such as a stop 37 against which the pinion 5 comes to bear axially. During the compression of the elastic member 31, the stop 37 makes it possible to avoid excessive compression of the elastic member 31 which can degrade it. For example, in the case where the elastic member 31 is a helical spring, the stop 37 makes it possible to avoid the phenomenon of contiguous turns where the turns come into contact with one another. This stop 37 is for example made by one or more studs or by a circular element. The stop 37 extends axially from a front face of the shoulder 29. In addition, the stop 37 extends, for example, between the elastic member 31 and the pinion body 23. Thus, the pinion 5 is movable between a stop position in which it rests against the stop element 33 and a rear position in which it comes into contact with the stop 37. The distance between the stop position and the rear position of the pinion 5 defines the stroke of the pinion 5 relative to the pinion body 23. This stroke is between 2 mm and 6 mm, in particular equal to 4 mm.

The value of the stiffness of the elastic member 31 can be chosen from a wide range of values, for example between 2000 N / m and 10000 N / m. Thus, the elastic member 31 is configured so that the prestress exerted on the pinion 5 in the abutment position against the circlip 33 is between 40 N and 80 N and preferably between 55 N and 65 N. In addition, the pinion 5 a, here, a mass between 40 g and 110 g, in particular of the order of 60 g, and the launcher 3 (comprising the pinion 5) has a mass between 250 g and 420 g, in particular of the order of 320 g. In the case of a helical spring, the number of turns of the elastic member 31 is for example between 2 and 4.

Furthermore, it should be noted that the elastic member 31 can be formed by several elastic elements such as for example several helical springs or several elastomers or even a combination of springs and elastomers, the different springs or elastomers being able to have stiffnesses and / or of different lengths and / or strokes and be assembled in series or in parallel.

In the example considered, the circlip 33 is in plan contact with the groove 32 and with the pinion 5 in the stop position of the pinion 5 relative to the pinion body 23.

With reference to FIGS. 3 to 5, the circlip 33 is described in more detail. Radial thickness

E of circlip 33 is substantially constant over its entire periphery. The radial thickness E of the circlip is substantially identical in any plane passing through the circlip and comprising the axis X, such a plane is notably illustrated in FIG. 4. When the circlip 3 3 is mounted in the groove 32, the axis X is the axis of revolution of the circlip. In a given plane, the radial thickness can be the difference between the maximum radius and the minimum radius.

The radial thickness E can be between 2 mm and 3 mm, preferably between 2.1 mm and 2.3 mm, preferably 2.24 mm.

The circlip also has an axial thickness E ′ between 1 mm and 1.3 mm, preferably 1.2 mm.

In the example considered, the circlip 33 has a substantially rectangular and substantially constant section along its periphery, that is to say in any plane passing through the circlip and comprising the axis X, for example that of FIG. 4.

This rectangular section can be seen in any plane crossing the circlip and including the axis. The axis of rotation of the launcher is the axis of revolution of the circlip.

In the example considered, the circlip has a radially inner face 40, a radially outer face 41 spaced from one another by a substantially constant radial distance corresponding to the radial thickness E, a first planar contact face 42 and a second planar contact face 43 substantially parallel to each other, the faces being in contact, respectively with the groove 32 and the pinion 5 when the pinion is in the stop position. The radially inner face 40 is in plan contact with the bottom of the groove 32.

In the example considered, the normal to these first and second contact faces 42, 43 form an angle less than 5 °, preferably 2 °, more preferably 1 °.

In the example considered, the circlip 33 may have blunt circumferential extension edges. The edges are rounded between two successive faces 40, 41, 42, 43 of the circlip. The radius R of the rounding can be between 0.1 mm and 0.3 mm, preferably between 0.15 mm and 0.2 mm.

In the example considered and with reference to FIG. 3, the circlip has an opening 45. This opening has a length of less than 2 mm, preferably less than 1 mm when the circlip 33 is in the free state, this is i.e. not mounted on the pinion body 23.

This length is a minimum distance between two points of the circlip along an orthoradial axis.

In the example considered, the circlip 33 therefore has the shape of a ring with a rectangular section open locally. The circlip 33 may have cut edges only at the opening 45.

In the example considered, the circlip has a ratio:

contact surface with the pinion body 47 contact surface with the pinion between 1 and 2.5, preferably between 1.7 and 2.3

The contact surface with the pinion body 47 is the intersection of the circlip and the pinion body 23, shown hatched. Such a surface is for example between 50 mm ² and 70 mm ² .

Circlip 33 has a maximum radius R _max between 9 mm and 10 mm and a minimum radius R _m i _n between 6.5 mm and 7.5 mm. The retaining ring here is made of high-quality steel with a high content of unalloyed carbon.

Finally, in the example considered, the circlip 33 has a structure, the fibers of which are all substantially oriented in a circumferential direction. The orientation 48 of these fibers is visible in FIG. 5 which is a micrograph of the cirlcip 33 obtained after chemical attack and in which the segment 49 is equivalent to 100 μm.

Alternatively, it will not depart from the scope of the invention if the starter, as previously described, is used in an outgoing pinion starter.

The invention finds applications in particular in the field of starters for thermal engines and in particular for thermal engines of motor vehicles but it could also be applied to any type of starter.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention from which one would not depart by replacing the various elements with any other equivalent.

Claims (9)

1. Launcher (3) for a starter (1) of a motor vehicle, capable of turning about an axis, comprising: - a pinion body (23) having a groove (32), - a pinion (5) capable of meshing with a crown of a heat engine, the pinion being slidably mounted along an axis (X) on the pinion body (23), the pinion having a stop position relative to the body of pinion, - at least one elastic member (21) mounted axially between the pinion and the pinion body to return the pinion to the stop position, - a metal circlip (33) having a fiber structure, the circlip being mounted in the groove, the circlip being in plan contact with the groove and the pinion in the position of abutment of the pinion relative to the pinion body, characterized in that the fibers of the fiber structure are substantially all oriented in a circumferential direction, and that the radial thickness (E) of the circlip is substantially constant over the whole of its periphery. 2. Launcher (3) according to claim 1, wherein the circlip (33) has blunt edges. 3. Launcher (3) according to any one of claims 1 and 2, the circlip (33) having a substantially rectangular section constant along its periphery. 4. Launcher (3) according to any one of the preceding claims, in which the circlip (33) has an opening (45) of length less than 2 mm, preferably less than 1 mm in the free state. 5. Launcher (3) according to any one of the preceding claims, in which the circlip (33) has a first planar contact face (42) and a second planar contact face (43) substantially parallel, the faces being in contact , respectively with the groove (32) and the pinion (5) when the pinion is in the stop position. 6. Launcher (3) according to the preceding claim, wherein the circlip (33) has a contact surface with the pinion body (47). , _ _. ratio: ---------------------------— _: ---------- between 1 and 2.5, from preferably contact surface with the pinion between 1, 7 and 2.3. 7. Launcher (3) according to any one of the preceding claims, in which the radial thickness (E) of the circlip is between 2mm and 3mm, preferably between 2.1mm and 2.3mm, preferably being of 2.24 mm. 8. Launcher (3) according to any one of the preceding claims, in which the 15 circlip (33) is obtained by winding a round wire previously flattened. 9. Motor vehicle starter (1) comprising a launcher (3) according to one of the preceding claims.