FR2982336A1 - CROWN FOR EPICYCLOIDAL TRAIN REDUCER - Google Patents

Abstract

The invention relates to a ring gear for epicyclic gear train, comprising an inner ring (3, 3 ') comprising internal teeth adapted to be meshing by planet wheels of the epicyclic gear train. The ring further comprises a housing (1, 1 ', 1 ") comprising means for securing with a cylinder head, and at least one damping means (51, 52, 53, 71, 72, 73, 74, 51 ', 52', 53 ', 71', 72 ', 73', 7A, 7B, 7C) for absorbing an energy peak between the ring (3, 3 ') and the housing (1, 1', 1 ") when the ring (3, 3 ') rotates relative to the housing (1, 1', 1") in a direction of rotation, in which the ring (3, 3 ') is rotatable relative to the housing (1, 1 ', 1 ") between a rest position and a compressed position. The damping means (51, 52, 53, 71, 72, 73, 74, 51 ', 52', 53 ', 71', 72 ', 73', 7A, 7B, 7C) is arranged to allow a deflection angularly at least 8 degrees to the X axis between the ring (3, 3 ') and the housing (1, 1', 1 ") without damage to the ring (3, 3 ') and the housing ( 1, 1 ', 1 ").

Description

Crown for epicyclic gearbox. TECHNICAL FIELD The present invention relates to a ring gear for an epicyclic gear train, in particular for motor vehicle starters, as well as a planetary reduction gear comprising such a ring gear. STATE OF THE PRIOR ART Crowns for epicyclic gearboxes generally comprise a substantially cylindrical casing, in which is inserted an inner ring, also called outer planet, which comprises an internal toothing which meshes the planet wheels of the reducer. The inner ring is immobile in rotation relative to the housing. Planetary gear reducers receive shocks, called tangential or circumferential shock, due to a torque between the housing of the ring and the cylinder head on which is fixed the echoing gear between the teeth of the inner ring and the planet wheels. This impact of shock generates premature wear of the ring and therefore the epicyclic reducer. In order to limit the tangential shocks, that is to say the torque peaks coming from the drive shaft on the ring, especially when starting for a starter, the document FR2829821 proposes to interpose damping blocks between the housing and the inner ring so as to limit the torque transmitted by the inner ring to the housing and thus limit the impact between the housing and the cylinder head. However, some of the gearboxes receive shocks of a very different amplitude, this is particularly the case for starters which are adapted to start a combustion engine whether it is in a stopping or stopping phase, also called a starter of type "stop start".

Indeed, during stopping phase, the starter may be required to restart the engine whose crankshaft rotates upside down resulting in a shock due to the torque (referred to in the following torque return) on the epicyclic gearbox which is much more important than the torque shock (called start torque) when the starter starts the engine off. The shock absorbing blocks are damaged by shocks due to the return torque and can tear, this can lead to the deterioration of the entire transmission chain, including the housing, the ring, the drive shafts and the starter rotor. This is because the tangential shocks from the inner ring are no longer absorbed by the dampers. In addition, the deterioration of the dampers leads to a higher noise generation when starting the vehicle.

SUMMARY OF THE INVENTION The aim of the invention is to overcome the drawbacks of the state of the art by proposing a ring gear for an epicyclic gear reducer which has a life time and a high resistance even when it undergoes very large amplitude shocks. different provoked, for example by the engine that can be in the off phase or stopped. "Shocks of very different amplitudes" means shocks of different amplitudes, the difference between the smallest damped pair, called mini torque and the largest damped torque, called maximum torque, is of the order of 10%. The term "mini-cushioned torque" is understood to mean the torque whose dampers are sufficiently flexible to damp the torque between the housing and the cylinder head by at least 10%.

By maximum cushioned torque is the torque whose dampers are stiff enough to dampen the shock between the housing and the cylinder head without it compresses to the end of their travel. Another object of the invention is to provide a ring gear for epicyclic gear train in which the noise is reduced over the long term. To do this, is proposed, according to a first aspect of the invention, a ring gear for epicyclic gear train, comprising: An inner ring comprising internal teeth adapted to be engaged by planet wheels of the epicyclic gear train, a housing comprising means for securing with a yoke and mounted against the housing, at least one damping means for absorbing a peak of energy between the ring and the housing when the ring rotates relative to the housing in a direction of rotation, in which the ring is rotatable relative to the ring between a rest position and a compressed position, characterized in that the damping means is arranged to allow an angular deflection of at least 8 degrees relative to the X axis between the ring and the housing without damaging the ring and the housing.

Indeed, increasing the degree of deflection allows the damping means to have a greater range of damping shock values. In addition, the fact of increasing the deflection makes it possible to lengthen the shock time and thus to distribute the energy to be absorbed over time and thus to reduce the energy peak to be damped.

The damping means is mounted to dampen the angular movements of the inner ring relative to the housing in at least one direction. In a starter, the damping means comprises mechanical characteristics making it possible in a first compression phase to damp start torques and in a second compression phase to damp return torques. The crown according to the invention may also have one or more of the following characteristics, taken individually or in any technically possible combination: the damping means, in the rest position, may have stiffness characteristics at least twice smaller than in end position; A damping means having such a difference in stiffness between the resting position and at the end of the stroke with an angular clearance of 8 ° having a material with a stiffness chosen according to the application, makes it possible to damp a large range of torque. ; The damping means may comprise at least one polyurethane pad; - The pads can be mounted in parallel and are pressed against a radial surface of the inner ring and a radial surface of the housing; The damping means may comprise at least three studs mounted functionally in parallel; Having three pins, reduces the size. Indeed, by distributing three studs mounted in parallel instead of one, allows for the same material pads having a smaller radial width; The damping means may comprise at least a first and a second torque damping means mounted between the ring and the housing for absorbing together a peak of energy between the ring and the housing when the ring rotates relative to to the housing in a direction of rotation, and in that the first and second damping members have a different stiffness coefficient and a different maximum clearance; Thus, the fact of mounting two damping means having a different coefficient of stiffness makes it possible to damp shocks due to different couples; Indeed, a first damping means acts on shocks whose mini torque is very different than the maximum torque damped by the first and the second damping means; The risks of tearing the shock absorber are thus limited, even after shocks due to maximum torque; - The second damping member may be a deformable block in a softer material than the materials of the ring and the housing and in that the first damping member may be a spring having a coefficient of stiffness smaller than that of the damper block. - The first (s) and second (s) torque damping member (s) can be mounted in series functionally. This allows that initially only one of the first or first members and then the first and second damping members and thus the damping means comprises a staircase strength resistance during its compression; - The ring may further comprise an intermediate piece located between the ring and the housing, wherein the intermediate piece is arranged between the first damping member and the second damping member so that the damping means can act between the ring and the intermediate piece and act between the intermediate piece and the housing; - The ring may further comprise pads disposed between the housing and the intermediate piece forming a travel stop of the displacement of the intermediate piece by the damping means at the rest position; - The ring may further comprise pads disposed between the inner ring and the intermediate piece forming a travel stop of the displacement of the inner ring by the damping means at the rest position; the first and second torque damping members can be connected in parallel; The ring, the damping means and the housing may be arranged so that the ring moves from the rest position to the compressed position and in a first step compressing only the first damping member and then, in a second step, the two members depreciation; The ring may further comprise pads disposed between the housing and the inner ring forming a stop at the rest position of the ring; The damping means may further comprise a plurality of damping members of the same material and shape as the first damping member and in that they are connected in series with the first member; The damping means may further comprise several damping members of the same material and same shape as the second damping member and in that they are mounted in series with the second member; The inner ring may comprise lugs protruding axially surrounded by the housing forming between them a housing, and in that the damping means is disposed in the housing. The invention also relates to a planetary reduction gear comprising a ring as described above.

The invention also relates to a starter comprising a gear as described above. The invention also relates to a starter comprising means 20 for starting a motor in a stopping phase comprising a gear as described above. The dependent claims will be inserted here. A second aspect of the invention is an epicyclic gear train for a motor vehicle starter having a crown according to the first aspect of the invention.

A third aspect of the invention relates to a motor vehicle starter of the epicyclic gear type comprising a ring gear according to the first aspect of the invention.

Other characteristics and advantages of the invention will become apparent on reading the nonlimiting description which follows for the understanding of which reference will be made to the appended drawings. Brief Description of the Drawings Figure 1A shows a perspective view of a crown according to a first embodiment. Figure 1B shows a front view of the ring shown in Figure 1A in the rest position. Fig. 2A and Fig. 2B both show a perspective view of a ring according to a second embodiment. Figure 3A shows a front view of the ring shown in Figure 3A in the rest position. FIG. 3B represents a front perspective view of a crown according to a third embodiment. FIG. 3C represents a front perspective view of the ring shown in FIG. 3A comprising a closure plate. Figure 3D shows a front view of the ring shown in Figure 3A, in a position in compression. Description of exemplary embodiments of the invention

In the figures, identical, similar or similar elements are designated by the same reference numerals. A ring gear for an epicyclic gearbox according to a first embodiment of the invention is described with reference to FIGS. 1A to 1B.

This ring comprises a housing 1 having an opening therethrough in which a reference axis 2 passes through its center. The housing 1 is preferably cylindrical about the reference axis 2. In this document, the term "axial" designates a direction parallel to the reference axis, by "radial", a direction perpendicular to the reference axis and by "angular", a direction defined by a line described by a point rotating about the reference axis 2. The ring also comprises an inner ring 3 which is mounted against the housing 1. The inner ring 3 also comprises an opening through which the axis 2 passes in its center. The inner ring 3 is preferably cylindrical about the reference axis. The inner ring 3 has an inner face 4 provided with teeth capable of being engaged by planet wheels of the reducer. In this embodiment, the inner ring 3 is mounted in axial abutment against the housing 1. The face, referred to in the following support face, of the inner ring 3 mounted against the housing 1 is not shown. The inner ring 3 has a sleeve 30 protruding axially from the bearing surface in the opposite direction of the teeth. The inner ring comprises at least one protrusion of support 32 which protrudes radially from the sleeve 30 of the inner ring 3 and projecting from the bearing face. In this case, in this illustrated embodiment, there are three protuberances of supports 31, 32 and 33, but it could have more or less. The ring comprises a first damping member 51 in the form of a spring. In this case, the ring comprises three damping members hereinafter called spring 51, 52, 53 of the same shape, and are in the same material and therefore have the same mechanical characteristics. The three springs 51, 52, 53 are in abutment respectively against the three protuberances of supports 31, 32, 33.

The springs 51, 52, 53 and the bearing protuberances 31, 32, 33 are preferably distributed circumferentially around the outer periphery of the sleeve 30 of the ring 3. In this case, each spring 51, 52, 53 are coil springs. In this first embodiment, the ring further comprises a connecting piece 6. This connecting piece 6 is mounted between the inner ring 3 and the casing 1. The connecting piece 6 also comprises a through opening whose axis 2 goes to its center. The intermediate piece 6 comprises a ring and radial internal lugs 61, 62, 63 and radial external lugs 64, 65, 66, 67.

The internal lugs 61, 62, 63 extend radially from the ring towards the axis 2. The external lugs 6 ', 65, 66, 67 extend radially from the ring towards the casing 1. The internal lugs 61, 62, 63 are evenly distributed angularly around the inner periphery of the connecting piece 6. The internal lugs 61, 62, 63 are therefore positioned between respectively the spring 53, 51, 52, and the support protrusion 31, 32, 33. Each spring 51, 52, 53 is mounted in one of the housings respectively formed by the protuberance 31, 32, 33, the radial internal lug 62, 63, 61, the inner periphery of the connecting piece, the outer periphery of the sleeve and the bearing face of the ring 3. A not shown closure plate is mounted radially against the housing 1 and closes the housing of the springs.

The springs 51, 52, 53 are connected in parallel with each other and therefore form a first damping means between the intermediate piece 6 and the inner ring 3. The helical springs 51, 52, 53 each have a shape of a circular arc conforming to the outer periphery of the sleeve 30. The springs 51, 52, 53, the ring 3 and the connecting piece 6 are mounted so that the ring 3 can compress the springs 51, 52, 53 relative to each other. to the connecting piece 6 by rotating in a direction of rotation called in the following direction of startup rotation. For example in the case of a starter, the direction of rotation to compress the damping means will correspond to the direction opposite to the direction of rotation of the electric motor of the starter to start the engine. The springs 51, 52, 53 may have the same stiffness value or different stiffness values for damping vibrations. The springs 51, 52, 53 can be mounted with play or without play in the housing. An assembly without play allows to damp from the beginning and therefore be responsive and thus prevent the torque takes power due to an acceleration for example of the rotor. An assembly with springs of different stiffness values makes it possible to have a damping staircase and thus to dampen a larger range of torque.

According to another example of this embodiment, the ring comprises a single damping member of the coil spring type. The casing 1 is formed by a ring 11 having a not shown bearing face intended to bear axially against the bearing face of the inner ring 3 and a closure face 12 covered by the not shown closure plate. The closure plate can be fixed by means of fasteners or can be overmolded on the ring 11.

The ring 11 comprises internal radial notches passing right through forming housings with the connecting piece 6. In this case, there are four housings 101, 102, 103, 104. The housings 101, 102, 103, 104 are closed by the outer periphery of the connecting piece 6 and the closure plate not shown. Each external radial lug 64, 65, 66, 67 of the connecting piece 6 are respectively housed in a housing 101, 102, 103, 104 forming a cavity between each axial wall of each housing and an axial radial lug wall. The ring further comprises a second damping member. This second damping member is a main damping pad. Its hardness is very different from the first depreciation organs. In this case, the crown of the embodiment shown in Figure 1A comprises several main damping pads of the same type. In this case, there are four main depreciation pads 71, 72, 73, 74.

Each main damping pad 71, 72, 73, 74 respectively extends circumferentially, respectively, an outer periphery of the connecting piece and the inner periphery of the housing 101, 102, 103, 104 and is housed respectively in the cavity of the housing 101, 102, 103, 104 formed by the axial wall of this housing and the external lug housed in this housing.

The housings 10 of the housing 1 and the main crushing pins 71, 72, 73, 74 are shaped so that, when a torque acts on the ring in the direction of startup rotation, the inner ring 3 exerts a pressure on the springs which damp a part of the shock and applies a force on the connecting piece, which compresses the main damping pads which themselves dampen the impact between the connecting piece and the housing.

In the following, to simplify the description, we will describe in detail one of the housing 101, and the elements that are housed therein. The other housings 102, 103, 104 are preferably identical to this housing described in detail. According to an exemplary embodiment shown, this housing 101 of the housing 1 contains, in addition to the damping pad 71, at least one damper 81. This damper 81 is preferably made of elastomer. This damper 81 is positioned in a second cavity of the housing 101 formed between the lug 64 and a second axial surface of the housing 101 so as to damp the rotation of the connecting piece 6 relative to the housing 1 in another direction of rotation than that of the starting rotation direction, called in the following direction of return rotation. More specifically, the damper 81 is located in the housing 101 so that, when the connecting piece 6 rotates relative to the housing 1 in this direction of return rotation, due to loosening of the main studs which push each their ergot respective in the direction of return rotation, the outer radial pin 64 comes, in the end stroke, in collision with the damper 81 so as to avoid contact between the housing and the connecting piece 6. Moreover, the studs the damping 71 and the damper 81 are preferably enclosed in a cavity closed by the closure plate so that the possible deformations of the damper 81 and the damping pad 71 are limited by the walls of this cavity closed. In this embodiment, the closed cavity in which the damper is contained is delimited axially by the bearing surface 6 of the housing 1 and by the closure plate. Thus, in case of rotation of the inner ring 3 relative to the housing 1, the protuberances compress the springs at first which have a lower reaction force at the beginning of compression than the pads of damping, then in a second step in addition to compressing the springs, the outer radial pins 64, 65, 66, 67 of the connecting piece 6 crash against the respective damping pads 71, resulting in a decrease in the volume of each closed cavity in which is contained one of the damping pad 71, 72, 73, 74. Each damping pad 71, 72, 73, 74 is then compressed in the respective cavity closed to a predetermined stress. The dimensions of each damping pad and of the closed cavity in which the respective damping pad is contained are chosen as a function of the maximum deformation desired for the damping pad. In order for the damping pad to be deformable in the closed cavity, it is possible for example to choose a damping pad which has a smaller volume than that of the closed cavity, or it is possible to choose a damping pad which is hollow. as shown in FIGS. 1A to 1B. Indeed, as can be seen in FIG. 1B, the damping pad has at its center a cylindrical hole that extends along the reference axis 2. The fact enclosing the damping pad 71 in the closed cavity makes it possible to control its deformations and to prevent the deformations of the damping pad from being random. Thus, the risks of tearing of the damping pad are limited, even after a large number of cycles of starting the vehicle using a ring according to the invention. A second embodiment shown in Figure 2 will now be described. Parts or parts having the same reference number are identical to the first embodiment. The crown of this embodiment is different from the previously described embodiment mainly in that it no longer comprises a connecting piece and that the first organ (s) and the second (s) ) member (s) are connected in parallel.

In this embodiment shown, the inner ring 3 'comprises at least two external radial protuberances 331A and 331B extending from the sleeve 30 outwards. Each external radial protuberance 331A and 331B respectively comprises a radial thrust surface 331A 'and 331B'.

The housing 1 'comprises a ring-shaped portion 11' and at least a first and a second radial projection respectively 110A, 110B, extending from the inner periphery of the ring 11 'towards the axis 2. The first radial projection 110A comprises a radial bearing surface 111A, visible in part in Figure 3B, mounted opposite a radial surface 331A ', forming between them a housing 91A. The second radial projection 110B comprises a radial bearing surface 121B mounted opposite the radial surface 332B ', forming between them a housing 91 B. In this case, the two housings have an arc shape of circle.

The ring comprises at least a first connecting member, in this case a spring 51 ', and a second connecting member, in this case a damping pad 71'. The first and the second members 51 'and 71' are functionally mounted in parallel respectively in the housings 91A and 92A. The spring 51 'is mounted prestressed in the housing 91A bears against the two radial bearing surfaces 11A and 331'. The damping pad 71 'is freely mounted in the housing 92A. In the embodiment shown in FIGS. 2A and 2B, the crown comprises in this case three first radial projections 110A, 110B, 110C and three external radial protuberances 331A, 331B, 331C forming between them three housings 91A, 91B, 91C in which are inserted three first damping members, in this case respectively three springs 51 ', 52', 53 'mounted prestressed. But the crown could comprise 1 or 2 or 4 or 5 slots with first damping member and as much second damping member. The first damping members are thus mounted together in parallel between the housing and the inner ring 2. In the embodiment shown in Figures 2A and 2B, the ring comprises in this case three second radial projections 120A, 120B , 120C referenced in Figure 2B and three external radial protuberances 332A, 332B, 332C forming between them three housings 92A, 92B, 92C in which is inserted three second damping members, in this case three free mounted damping pad 71 ', 72', 73 '. But the crown could comprise 1 or 2 or 4 or 5 slots with second damping member 10 and the same second damping member. The second damping members are thus mounted in parallel between the housing and the inner ring 2 and with the first damping member or bodies. In the embodiment shown in FIGS. 2A and 2B, the ring further comprises three other housings in which are inserted three pads of damping 81 ', 82', 83 'to avoid contact between the projections 331A, 331B , 331C and the housing 1 '. In this case, in the embodiment of Figures 2A and 2B, each housing in which is inserted a damper 81 ', 82', 83 'is formed respectively between a protrusion 331A, 331B, 331C and a radial surface of the housing 1 . In other words, the protrusion 331A makes it possible to form on one side the housing 91A and on the other the housing for the damper 81 '. A third embodiment shown in FIGS. 3A, 3B, 3C, 3D will now be described. Parts or parts having the same reference number are identical to the first embodiment. The crown of this embodiment is different from the embodiment described above, mainly in that the damping means comprises only one type of member for damping when the inner ring rotates in the direction of start. In this illustrated embodiment, the inner ring 3 'comprises at least first and second outer radial protuberances 331A and 332A extending from the sleeve 30 outwardly. The two protuberances form a stepped protrusion. Each external radial protuberance 331A and 332A respectively comprises a radial thrust surface 331A 'and 332A'. The housing 1 "comprises a ring-shaped portion 11 'and at least a first radial projection respectively 110A', extending from the inner periphery of the ring 11 'towards the axis 2. The first radial projection 110A comprises a radial bearing surface 111A 'mounted opposite the radial surface 331A', forming between them a housing 91 'In this case, the housing has an arcuate shape.

The ring comprises at least one damping member 7A mounted in the housing 91 'formed between the two radial surfaces 331A' and 111A ', one of which belongs to the inner ring 3' and the other to the case 1 ". damping has a characteristic called the maximum length of deflection, corresponding to the length of the member minus the length of the member in maximum compression while remaining in its elastic zone (the length of the member being taken in the direction of the compression of the crown) The damping member comprises a maximum length of deflection, allowing the inner ring 3 'to have an angular displacement of at least 8 ° This angular displacement corresponds to the angular displacement between the inner ring and in the maximum allowable external casing of the ring gear.In a starter, the damping member must have a characteristic of stiffness allowing, whatever the starting phase, damping of at least 50% the shock of the starting (motor stopped or in stop phase positive or negative rotation) A polyurethane damping member of hardness between 70 and 110 shore A, and having dimensions chosen to attenuate the two shocks of different amplitudes to restart a heat engine. According to one embodiment, the polyurethane damping member has a hardness of 90 Shore A with dimensional characteristics of 25 mm in length, 8.7 mm in height and 8.8 mm in width. Such a product can be the one referenced by the brand Strathane ®: 100M green 90 shore A. Of course, all other products having the same mechanical characteristics with dimensional characteristics defined according to the damping factor necessary for the application can also be incorporated. In this embodiment shown, the inner ring 3 'comprises at least two external radial protuberances 331A and 332A extending from the sleeve 30 outwards. Each external radial protuberance 332A respectively comprises a radial contact surface 332A ".

The crown comprises in this case three first radial projections 110A ', 110B', 110C 'and three external radial protuberances 331A, 331B, 331C forming between them three housings 91A', 91B ', 91C' in which are inserted the three bodies of 7A, 7B, 7C damping. In this case the three damping members are mounted prestressed. But the crown could include 1 or 2 or 4 or 5 housing damping member and as damping member. The damping members are therefore mounted together in parallel between the housing and the inner ring 2. In the embodiment shown in FIGS. 3A, 3B, 3C and 3D, the ring further comprises three other housings in which are inserted three pads damping 81 ', 82', 83 ', to avoid contact between the projections 331A, 331B, 331C and the housing 1'. In this case, in this embodiment, each housing in which is inserted a damper 81 ', 82', 83 'is formed between a protrusion 331A and radial surface of the housing 1'. In other words, the protrusion 331A makes it possible to form on one side the housing 91A 'and on the other the housing for the damper 81'.

In this embodiment, the three members are identical and the three housings are identical and are distributed regularly angularly about the axis 2. It will now be described a single damping member 7A and a single housing 91A 'in order to make the description clearer. The other two damping members 7B and 7C and the other two housings 91B 'and 91C' are identical. The second radial protrusion 332A forms a stop when the inner ring 3 rotates in the direction of starting rotation relative to the housing 1. This has the advantage of preventing the compression member from deforming beyond its elastic zone. . The projection 110A 'comprises a lug 1100A' forming with the ring 11 'a notch 931A' forming part of the housing 91A 'This lug 1100A' comprises a ramp allowing the damping member 7A to deform without tearing. In fact, this ramp prevents the damping member from being inserted between the protuberance 332A and the radial projection 110A 'during the compression of this damping member 3C represents the ring comprising a closure plate This closure plate 24 is integral with the housing 1. The ring further comprises lugs 241 for being fixed in rotation with a cylinder head, such as a starter yoke, inside thereof. The crown may further comprise a ramp-shaped lug 242. This lug makes it possible, when the ring gear is in a starter, to be used as a passage for a lever of a switch to move a starter gear forward or backward. 242 ergot in the shape of a ramp can also be used as a tipping point for the starter lever. Figure 3D shows the crown without its closure plate during an impact. The angle a represents the angular displacement of the inner ring 3 "relative to the housing 1". As can be seen in the figure, the angle a is equal to eight degrees. The angle p corresponds to the angular displacement that the inner ring can still achieve relative to the housing. The maximum angular displacement between the inner ring and the housing is therefore equal to the sum of the angle a and the angle p. In this case, the maximum angular deflection is equal to twenty-one degrees. According to another embodiment, the three members 7A, 7B, 7C do not have the same length. In this case, at least one of the three members is freely mounted in its respective housing allow to have a damping staircase and thus dampen a larger range of torque. Thus, in the event of a shock due to a starting torque, only the damping members in contact with a radial thrust surface act by applying a reaction force between the inner ring and the appropriate housing to damp at least 10% of the shock. and in case of shock due to a return torque, initially, only the organs described above act and then the other organs act. According to the three embodiments, the ring further comprises at least one notch or a lug on its inner periphery to be mounted (e) in rotational connection with the carcass of a starter. In this case, as shown in FIG. 2 and FIGS. 3A, 3B, 3C and 3D, the ring comprises four notches A on the outer periphery of the ring of the outer casing.

According to all the embodiments, the housing may comprise a chamfer B on the radial face of the outer casing opposite the inner face 4 of the inner ring 3.

Claims (19)

REVENDICATIONS1. Crown for a planetary gear reducer, comprising: - an inner ring (3, 3 ') comprising internal teeth adapted to be engaged by planet wheels of the epicyclic gearbox, - a housing (1, 1', 1 ") comprising means for securing with a yoke, - at least one damping means (51, 52, 53, 71, 72, 73, 74, 51 ', 52', 53 ', 71', 72 ', 73', 7A, 7B, 7C) for absorbing an energy peak between the ring (3, 3 ') and the housing (1, 1', 1 ") when the ring (3, 3 ') rotates relative to the housing (1, 1 ', 1 ") in a direction of rotation, wherein the ring (3, 3') is rotatable relative to the housing (1, 1 ', 1") between a rest position and a position compressed, characterized in that the damping means (51, 52, 53, 71, 72, 73, 74, 51 ', 52', 53 ', 71', 72 ', 73', 7A, 7B, 7C) is arranged to allow an angular deflection of at least 8 degrees with respect to the X axis between the ring (3, 3 ') and the casing (1, 1', 1 ") without damaging the ring (3, 3 ') and the casing (1, 1', 1"). 2. Crown for epicyclic gear as claimed in claim 1, characterized in that the damping means (51, 52, 53, 71, 72, 73, 74, 51 ', 52', 53 ', 71', 72 ', 73', 7A, 7B, 7C), in the rest position, has stiffness characteristics at least 2 times smaller than in the end position. 3. Crown for epicyclic gear train according to claim 2, characterized in that the damping means comprises at least one stud (71, 72, 73, 74, 71 ', 72', 73 ', 7A, 7B, 7C ) in polyurethane. 4. crown for epicyclic gear train according to claim 3, characterized in that the pads (7A, 7B, 7C) are connected in parallel and are pressed against a radial surface of the inner ring and a radial surface of the housing. 5. Crown for epicyclic gear train according to claim 2, characterized in that the damping means (51, 52, 53, 71, 72, 73, 74, 51 ', 52', 53 ', 71', 72 ', 73') comprises at least one first (51, 52, 53, 51 ', 52', 53 ') and second means (71, 72, 73, 74, 71', 72 ', 73') of damping torque mounted between the ring (3, 3 ') and the housing (1, 1') for absorbing together a peak of energy between the ring and the housing (1, 1 ') when the ring (3, 3 ') rotates relative to the housing (1, 1') in a direction of rotation, characterized in that the first and the second damping members have a different stiffness coefficient and a different maximum clearance. 6. Crown for epicyclic gear train, according to the preceding claim, wherein the second damping member (71, 72, 73, 74, 71 ', 72', 73 ') is a deformable block in a softer material than the materials of the ring (3, 3 ') and the casing (1, 1') and in that the first damping member (51, 52, 53, 51 ', 52', 53 ') is a spring having a coefficient of stiffness smaller than that of the damping block. The ring according to any one of claims 5 and 6, wherein the first (51, 52, 53) and second (71, 72, 73, 74) torque damping members are serially connected in series. 8. Crown according to the preceding claim, further comprising an intermediate piece (6) located between the ring (3) and the housing (1), wherein the intermediate piece (6) is arranged between the first damping member (51). , 52, 53) and the second damping member (71, 72, 73, 74,) so that the damping means can act between the ring (3) and the intermediate piece (6) and act between the intermediate piece (6) and the housing (1). 9. Crown according to the preceding claim, further comprising pads disposed between the housing (1) and the intermediate piece (6) forming a travel stop of the displacement of the intermediate piece (6) by the damping means at the position rest. 10. A crown according to claim 8 or 9, further comprising studs disposed between the inner ring (3) and the intermediate piece (6) forming a travel stop of the displacement of the inner ring (3) by the damping means. at the rest position. The crown of claim 5 or 6, wherein the first and second torque damping members are connected in parallel. 12. Crown according to the preceding claim, wherein the ring (3 '), the damping means and the housing (1') are arranged so that the ring (3 ') moves from the rest position to the compressed position and in a first time compressing only the first damping member and then in a second time the two damping members. 13. Crown according to any one of claims 11 or 12, further comprising pads disposed between the housing (1 ') and the ring (3') forming an internal stop at the rest position of the ring (3 '). . 14. A crown according to any one of claims 5 to 13, wherein the damping means further comprises a plurality of damping members of the same material and same shape as the first damping member and in that they are mounted in series with the first member. 15. A crown according to any one of claims 5 to 14, wherein the damping means further comprises several damping members of the same material and same shape as the second damping member and in that they are mounted in series with the second member. 16. A crown according to any one of the preceding claims, wherein the inner ring (3, 3 ') comprises lugs protruding axially surrounded by the housing (1, 1', 1 ") forming between them a housing, and the damping means is arranged in the housing. An epicyclic gear unit comprising a ring gear according to any one of the preceding claims. 18. Starter comprising a gearbox according to the preceding claim. 19. A starter comprising means for starting a stopping motor comprising a gear unit according to claim 17.