EP3325798B1 - Starter drive of a vehicle - Google Patents

Description

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 to allow the pinion to move towards the crown.

One of the major problems with starters is ensuring good meshing of the pinion with the ring gear. Indeed, depending on the state of the heat engine, the movement of the crown differs, which increases the risk of longer or incomplete gearing. Indeed, in the case of a cold start, the crown is immobile during gearing but in the case of a hot start (common case with “stop and start” mechanisms which allow the engine to be stopped thermal when the vehicle is stationary, in particular due to traffic conditions (traffic jams, traffic lights, etc.), the crown may still be rotating during gearing. Furthermore, in the case of hot starts, the crown can rotate in the direction of rotation of the pinion but can also rotate in the opposite direction during the swinging phase preceding the stopping of the crown, which makes it even more difficult to start. pinion gear with crown. If the torque is transmitted to the pinion by the electric motor before the pinion meshes with the ring gear, this can lead to premature wear of the pinion and/or ring gear as well as increased noise, particularly during start-up phases. hot.

Patent applications FROM 10 2012 210684 A1 , DE 10 2006 007281 A1 , FROM 10 2011 085279 A1 And US 2010/257975 A1 are very interesting representatives of the prior art.

It is therefore necessary to find a solution to reduce the wear of the pinion and/or the crown during the phases of engagement of the pinion with the crown, particularly during hot starts.

• une douille comportant un épaulement et un élément d'arrêt,
• un pignon monté coulissant sur la douille entre l'élément d'arrêt et l'épaulement,
• au moins un organe élastique monté entre le pignon et l'épaulement et étant adapté pour présenter une position de repos dans laquelle le pignon est en appui sur l'élément d'arrêt et une position comprimée dans laquelle le pignon est éloigné dudit élément d'arrêt,

dans lequel l'organe élastique est monté, dans sa position de repos, de façon à ce que le pignon soit précontraint avec une charge comprise entre 40 N et 80 N.For this purpose, the present invention relates to a launcher for a motor vehicle starter comprising:

• a socket comprising a shoulder and a stopping element,
• a pinion mounted sliding on the sleeve between the stopping element and the shoulder,
• at least one elastic member mounted between the pinion and the shoulder and being adapted to present a rest position in which the pinion is resting on the stopping element and a compressed position in which the pinion is moved away from said blocking element stop,

in which the elastic member is mounted, in its rest position, so that the pinion is preloaded with a load of between 40 N and 80 N.

Indeed, using numerical simulations, it was observed that such prestressing made it possible to apply a stress on the pinion, when it 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 meshing of the pinion with the crown. This therefore reduces gear time and noise and also reduces wear on the crown and pinion.

According to another aspect of the present invention, the elastic member is mounted, in its rest position, so that the pinion is preloaded with a load of between 55 N and 65 N.

According to an additional aspect of the present invention, the pinion has a mass of between 40 g and 110 g, in particular of the order of 60 g, and in which the launcher has a mass of between 250 g and 420 g, in particular of 'order of 320 g.

According to an additional aspect of the present invention, the pinion has a travel between the stopping element and the shoulder of between 2 mm and 6 mm, in particular equal to 4 mm. Indeed, a stroke of less than 2 mm does not allow optimal use of the elastic member which would not provide sufficient acceleration to the pinion. In addition, a stroke greater than 6 mm would increase the axial bulk of the machine without improving the usefulness of the elastic member. Thus, the fact that the pinion has a stroke in this range combined with the fact that the latter also has a certain level of preload makes it possible to provide the pinion with acceleration allowing it to then improve the meshing of the pinion with the crown.

According to another aspect of the present invention, the elastic member has a stiffness of between 2000 N/m and 10000 N/m.

According to an additional aspect of the present invention, the elastic member is a spring, in particular a helical spring.

According to an additional aspect of the present invention, the spring has a number of turns of between two and four.

According to another aspect of the present invention, the pinion is mounted movable between a front position in which the pinion is in support with a stopping element and a rear position in which the pinion is in support against a stop and compresses the member elastic against the shoulder.

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

According to another aspect of the present invention, the elastic member is arranged so that, when the elastic member is in the compressed position, the pinion is at a distance of at least 2 mm from the stopping element and is distant of the shoulder.

According to an additional aspect of the present invention, the starter comprises at least one tooth-tooth spring arranged at a contactor and adapted to exert an axial force on the pinion via a fork and in which the force exerted by the elastic member on the pinion, in its rest position, is greater than the force exerted by said tooth-tooth spring on said pinion.

Other characteristics and advantages of the invention will appear in the description which will now be given, with reference to the appended drawings which represent, by way of indication but not limitation, a possible embodiment.

• la figure 1 représente, schématiquement et partiellement, une vue en coupe longitudinale d'un démarreur selon un mode de réalisation de la présente invention ;
• la figure 2 représente, schématiquement et partiellement, une vue en coupe longitudinale d'un lanceur d'un démarreur selon un mode de réalisation de la présente invention ;
• la figure 3 représente, schématiquement et partiellement, le démarreur de la figure 1 dans une première position ;
• la figure 4 représente, schématiquement et partiellement, le démarreur de la figure 1 dans une deuxième position ;
• la figure 5 représente, schématiquement et partiellement, le démarreur de la figure 1 dans une troisième position ;
• la figure 6 représente, schématiquement et partiellement, le démarreur de la figure 1 dans une quatrième position ;
• la figure 7 représente, schématiquement et partiellement, le démarreur de la figure 1 dans une cinquième position ; et
• la figure 8 représente un graphique de l'efficacité de l'engrenage entre le pignon et la couronne en fonction du niveau de précontrainte du pignon pour différente raideur de l'organe élastique.

On these drawings:

• there figure 1 represents, schematically and partially, a longitudinal sectional view of a starter according to one embodiment of the present invention;
• there figure 2 represents, schematically and partially, a longitudinal sectional view of a launcher of a starter according to one embodiment of the present invention;
• there Figure 3 represents, schematically and partially, the starter of the figure 1 in a first position;
• there figure 4 represents, schematically and partially, the starter of the figure 1 in a second position;
• there figure 5 represents, schematically and partially, the starter of the figure 1 In a third position;
• there Figure 6 represents, schematically and partially, the starter of the figure 1 in a fourth position;
• there Figure 7 represents, schematically and partially, the starter of the figure 1 in a fifth position; And
• there figure 8 represents a graph of the efficiency of the gearing between the pinion and the crown as a function of the level of preload of the pinion for different stiffness of the elastic member.

In these drawings, the same reference numbers represent the same elements or elements having an identical function.

The following achievements are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features only apply to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

In the remainder of the description, the “front part” of the launcher or starter corresponds to the part located on the side of the motor ring gear and the “rear part” corresponds to the part opposite the motor ring gear. Thus, a “forward” direction corresponds to a direction towards the “front part” of the launcher or starter.

There figure 1 represents a diagram of a starter 1. The starter 1 comprises a launcher 3, an electric motor 7 intended to drive the launcher 3 in rotation, 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 an air gap 19 In general, two coils are used, a pickup coil and a holding coil, the pickup coil being used in addition to the holding coil to move the mobile 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 continuation of the description we will limit ourselves to designating a coil 15 (which can therefore include several coils).

The contactor 13 also comprises a rod 18 movable in translation relative to the movable core 17 of the contactor 13. A spring called a tooth-tooth spring 20 is positioned at the interface between the movable 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 tooth-tooth spring 20 has, for example, a stiffness of approximately 11 N/mm and a length at rest of the order of 22 mm and is mounted with a preload of approximately 45 N. The contactor 13 may also include other springs configured to return the mobile 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 powered.

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 to transmit the force or the torque between the fork 21 and the rod 18 such as for example a pivot connection made by a screw-nut assembly.

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 with respect 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 powered.

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 launcher 3 is therefore equal to 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 of the launcher 3 is, here, carried out via a reducing ring 11 arranged at the front end of the cylinder head 9.

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

Launcher 3 is shown in more detail on the figure 2 . The launcher 3 comprises a sleeve 23 mounted movable in rotation and in axial translation on a shaft 25 via bearings 27, for example needle bearings. The shaft 25 extends along an axis 6. The front part of the socket 23 is therefore the part located on the side of the motor ring gear 6 and the rear part of the socket 23 is the part of the socket 23 located on the side of the electric motor 7.

The socket 23 comprises a stopping element 33 disposed in front of the pinion 5 and a shoulder 29 disposed behind the pinion 5. The stopping element 33 is for example a circlip placed in a groove of the socket 23.

An elastic member 31, for example a helical spring or an elastomer, is arranged around the axis of the sleeve 23 and bears on the one hand against the shoulder 29 of the sleeve 23 and on the other hand against the pinion 5.

Thus, in a rest position of the elastic member 31 where the pinion 5 is supported on the stopping element 33, the pinion 5 is forced by the elastic member 31 against said stopping element 33. elastic member 31 allows, by compressing, a translational movement of the sleeve 23 when the pinion 5 is in tooth-to-tooth position with the motor ring gear 6, that is to say when the teeth of the pinion 5 are in contact with the teeth of the motor crown 6 without there being any gear between the two.

Furthermore, the shoulder 29 comprises, for example, an axial projection such as a stop 37 against which the pinion 5 bears. When compressing the elastic member 31, the stop 37 makes it possible to avoid excessive compression of the elastic member 31 which could damage 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 each other. 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 sleeve 23. Thus, the pinion 5 is mobile between a front position in which it rests against the stopping element 33 and a rear position in which it comes into contact with the stop 37. The distance between the front position and the rear position of the pinion 5 defines the stroke of pinion 5 relative to socket 23. Numerical simulations have made it possible to define that the optimal stroke of pinion 5 is between 2mm and 6mm, in particular 4mm. In addition, the sleeve is itself movable in axial translation relative to the shaft 25 between a position disengaged with the motor ring gear 6 and a position engaged with said ring gear. In the engaged position, the sleeve 23 rests on a stop 38 placed on a front part of the shaft 25.

The numerical simulations make it possible to identify and determine the value of the influence parameters making it possible to optimize the gearing of the pinion 5 with the motor ring gear 6 and thus to determine the optimal characteristics of the elastic member 31. For this, Optimization criteria for the gearing of pinion 5 on motor ring gear 6 are defined. These criteria include for example the engagement time of the pinion 5 on the motor ring gear 6. In addition, the result of the numerical simulations depends on the characteristics of the launcher 3, in particular the weight of the launcher 3 or the size of the pinion 5. However, for reduce production costs, the same elastic member 31 can be used for several types of launcher 3 so that an average can be carried out on the characteristics of different launchers 3 to obtain the characteristics of the elastic member 31 allowing almost -optimal for different launchers.

Thus, these numerical simulations have shown, contrary to what those skilled in the art might have expected, that the value of the preload applied to the pinion 5 by the elastic member 31 has a strong influence on the start of the gearing of the pinion 5 with the motor ring gear 6, that is to say on the entry of the pinion 5 into the motor ring gear 6. On the contrary, the stiffness value of the elastic member 31 has little influence . By little influence of the stiffness of the elastic member 31, we mean that the value of the stiffness can be chosen in a wide range of values, for example between 2000 N/m and 10000 N/m without this greatly influences the optimization parameters of the gearing of pinion 5 with the motor ring gear 6.

Thus, the elastic member 31 is configured so that the preload exerted on the pinion 5 in the rest position against the stopping element 33 is between 40 N and 80 N and preferably between 55 N and 65 N.

In addition, the pinion 5 has, here, a mass of 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 of between 250 g and 420 g, in particular of the order of 320 g. The stiffness and preload values of the elastic member 31 can therefore be adapted as a function of the mass of the launcher 3.

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 or different lengths and/or strokes and be assembled in series or in parallel.

The operation of the starter 1 during a start and the gearing of the pinion 5 with the motor ring gear 6 will now be described from the figures 3 to 7 .

There Figure 3 represents the starting position of starter 1 when stopped. When a user sends a start command, the coil 15 of the contactor 13 is energized, which causes the moving part or mobile core 17 to move towards the fixed part 16 of the magnetic core. The movement of the mobile core 17 causes the tilting of the fork 21 and the movement of the launcher 3 towards the front and therefore of the pinion 5 towards the motor ring gear 6 as shown in the Figure 4 . When pinion 5 comes into contact with motor ring gear 6, two cases can arise.

In a first case, the pinion 5 arrives directly in a gear interval of the motor ring gear 6 and can therefore mesh directly with the motor ring gear 6. However, this first case is relatively rare, particularly in the case of starting hot since the motor ring 6 is rotating.

In a second case, which is therefore the most common case, the pinion 5 comes into tooth-to-tooth contact with the motor ring gear 6 as shown on the figure 4 .

The inertia of the launcher 3 then causes the compression of the elastic member 31 which absorbs this energy. When the elastic member 31 is compressed (the pinion 5 does not necessarily reach the stop 37), as the movable core 17 continues to move towards the fixed part 16, the tooth-tooth spring 20 is then compressed as shown in the figure. figure 5 . In practice, the compressions of the elastic member 31 and the tooth-tooth spring 20 can be done simultaneously. However, the compression of the elastic member 31 is faster than that of the tooth-tooth spring 20. The mobile core 17 then continues to move, independently of the pinion 5 due to the crushing of the tooth-tooth pinion 20, until it comes to rest on the fixed core 16.

The fixed core 16 pushes a mobile contact which comes into contact with electrical terminals so as to create the conjunction of the contactor 13 in order to power the electric motor 7. The electric motor 7 then causes the rotation of the launcher 3 around the axis x.

Thus, once compressed, the elastic member 31 and the tooth-tooth spring 20 apply a strong stress on the pinion 5 towards the front, in the direction of the motor ring gear 6, so that, when a gear interval appears between the pinion 5 and the motor ring gear 6 (thanks to the rotation of the pinion 5), the pinion 5 is projected into this interval by the action of the elastic member 31. In fact, the elastic member 31 having a large stiffness, a significant preload and a short stroke (between 2 and 6mm), its action becomes preponderant compared to that of the tooth-tooth spring 20 when a gear gap presents itself. By gear interval we mean a position of the pinion 5 where its teeth are opposite a space between two successive teeth of the motor ring gear 6. Indeed, before the electric motor 7 reaches its full rotation speed, the pinion 5 rotates at low speed which allows it to position itself in this gear interval.

The entry of pinion 5 into the engine ring therefore occurs quickly by relaxing the elastic member 31 as shown in the Figure 6 then the action of the tooth-tooth spring 20 completes the action of the elastic member 31 and makes it possible to continue to exert a constraint on the pinion 5 when the elastic member 31 arrives in the rest position so as to completely engage the pinion 5 with the motor crown 6 as shown on the Figure 7 . Once pinion 5 is completely meshed with motor ring gear 6, said pinion transmits a significant torque to said ring gear to start the heat engine.

Thus, the use of an elastic member 31 configured to apply a preload of between 40 N and 80 N to the pinion 5 makes it possible to improve the gearing of the pinion 5 with the motor ring gear 6. The elastic member 31 therefore makes it possible to 'engage the gear by engaging the teeth of the pinion 5 with the teeth of the motor ring gear 6 and the tooth-tooth spring 20 allows this gear to be completed. The prestressing of the elastic member 31 makes it possible to obtain sufficient force to allow the pinion 5 to quickly enter into gear with the motor ring gear 6 when a gear gap occurs, regardless of the movement of the motor ring gear (when stationary, rotation in one direction or in the opposite direction).

The present invention therefore makes it possible, through a configuration of the elastic member 31 and the pinion 5, which does not require additional costs, to obtain faster and more fluid gearing of the pinion 5 on the motor ring gear 6, avoiding rebounds. of the pinion, and thus reduce the wear of the pinion 5 and the motor ring gear 6 as well as the noise emitted by the starter 1 when starting. The elastic member 31 therefore acts in addition to the tooth-tooth spring 20 to allow effective gearing of the pinion 5 with the motor ring gear 6.

There figure 8 illustrates the level of efficiency of the gear on a sample of a pinion and a crown as a function of the level of preload of the pinion for different value of stiffness of the elastic member. We thus notice that when the pinion has a preload with a load between 40 N and 80 N, then the gearing of the pinion with the crown has good efficiency (greater than 0.8). In addition, this efficiency is further improved (greater than 0.9), when the pinion has a preload with a load between 55 N and 65 N. The gear efficiency therefore depends little on the stiffness of the elastic member. which is in this example between 2000 N/m and 10000 N/m. By efficiency, we mean a gear, a pinion in a ring gear, fast and with reduced noise. In addition, a pinion of the starters of the prior art generally has a preload with a load of the order of 30 N. It is therefore clear that this level of preload of the pinion has an effectiveness of the order of 0.5 which is significantly lower than the solution proposed in a starter as previously described with reference to the present invention.

Alternatively, we 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 preceding description has been given by way of example only and does not limit the field of the invention from which one would not escape by replacing the different elements with any other equivalents.

Claims (11)

1. Starter drive assembly for a motor vehicle starter (1), comprising:

   - a bushing (23) having a shoulder (29) and a stop element (33),

   - a pinion (5) mounted so as to slide on the bushing (23) between the stop element (33) and the shoulder (29),

   - at least one elastic member (31) mounted between the pinion (5) and the shoulder (29) and being designed to have a rest position in which the pinion (5) bears on the stop element (33) and a compressed position in which the pinion (5) is remote from said stop element (33),

   characterized in that the elastic member (31) is mounted, in its rest position, in such a way that the pinion (5) is preloaded with a load of between 40 N and 80 N.
2. Starter drive assembly according to Claim 1, wherein the elastic member (31) is mounted, in its rest position, in such a way that the pinion (5) is preloaded with a load of between 55 N and 65 N.
3. Starter drive assembly according to Claim 1 or 2, wherein the pinion (5) has a mass of between 40 g and 110 g, in particular of the order of 60 g, and wherein the starter drive assembly (3) has a mass of between 250 g and 420 g, in particular of the order 320 g.
4. Starter drive assembly according to one of the preceding claims, wherein the pinion (5) has a travel between the stop element (33) and the shoulder (29) of between 2 mm and 6 mm, in particular equal to 4 mm.
5. Starter drive assembly according to one of the preceding claims, wherein the elastic member (31) has a stiffness of between 2000 N/m and 10000 N/m.
6. Starter drive assembly according to one of the preceding claims, wherein the elastic member (31) is a spring.
7. Starter drive assembly according to Claim 6, wherein the spring has a number of turns of between two and four.
8. Starter drive assembly according to one of the preceding claims, wherein the pinion (5) is mounted so as to be able to move between a front position in which the pinion (5) bears on a stop element (33) and a rear position in which the pinion (5) bears against an abutment (37) and compresses the elastic member (31) against the shoulder (29).
9. Motor vehicle starter comprising a starter drive assembly according to one of the preceding claims.
10. Starter according to Claim 9, wherein the elastic member (31) is arranged so that, when the elastic member (31) is in the compressed position, the pinion (5) is at a distance of at least 2 mm from the stop element (33) and is remote from the shoulder (29).
11. Starter according to Claim 9 or 10, comprising at least one tooth-against-tooth spring (20) disposed at a contactor (13) and designed to exert an axial force on the pinion (5) via a fork (21) and wherein the force exerted by the elastic member (31) on the pinion (5), in its rest position, is greater than the force exerted by said tooth-against-tooth spring (20) on said pinion (5).

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