FR2838490A1 - Automobile double damping flywheel comprises two coaxial flywheels connected by radial strips elastically deformable in bending, strips encastered at external radial end in intermediate ring free to rotate relative to flywheels - Google Patents

Abstract

The double damping flywheel comprises two coaxial flywheels (10) connected to rotate by a torsion damper device with radial strips (22) elastically deformable in bending. The strips are encastered at their external radial ends in an intermediate ring (24) free to rotate relative to the flywheels. The internal ends of the strips engage with the flywheels so that the maximum angular displacement between the flywheels is greater than that corresponding to the maximum bending of the strips.

Description

is reached.

  The invention relates to a double damping flywheel, in particular for a motor vehicle, comprising two coaxial flywheels, mounted for rotation one on the other by means of a bearing and linked in rotation one

  to the other by a damping device.

  In a motor vehicle, one of the flywheels is fixed at the end of a drive shaft, such as the crankshaft of an internal combustion engine, and the other is connected by a clutch to the drive shaft. a transmission,

  such as the input shaft of a gearbox.

  The damping device comprises a set of springs or elastically deformable means and friction means, for absorbing and damping vibrations, jolts and irregularities in rotation

  transmitted by one or other of the steering wheels.

  In a known embodiment, the springs are springs

  helicoidal circumferential arrangement between the steering wheels.

  In another known embodiment, the springs are springs

  helicals arranged radially between the flywheels.

  In another embodiment, described in particular in document FR-A815273, the springs are elastically deformable blades in bending, which are substantially radial and fixed at one end to one of the flywheels and which are guided at their other end on the other flywheel, so that an angular movement between the flywheels causes an elastic bending of the blades which opposes the angular movement. Stops

  curved fixed on the first mentioned flywheel limit the bending of the blades.

  An advantage of this damping device with elastically deformable blades in bending is the quasi insensitivity to centrifugal forces and the progressive increase in the stiffness of the blades with the transmitted torque, this stiffness varying as the inverse of the

free length of the blades.

  A drawback of this device is the small angular clearance allowed between the flywheels, this clearance corresponding to the bending of the blades. One of the aims of the present invention is to improve this known device by eliminating this drawback. The subject of the invention is therefore a double damping flywheel comprising a damping device with flexible blades, the flywheels of which can have a large relative angular movement,

around 60 for example.

  The invention also relates to a double damping flywheel of this

  type, which is economical and reliable and which has a reduced axial size.

  To this end, it proposes a double damping flywheel, in particular for a motor vehicle, comprising two coaxial flywheels, mounted for rotation one on the other by means of a bearing and linked in rotation one to the other. The other by a damping device with substantially radial lamellae, distributed uniformly around the axis of rotation of the flywheels and elastically deformed in bending during an angular movement between the flywheels, characterized in that the damping comprises an intermediate ring coaxial with the flywheels and free to rotate relative to the flywheels, this begue cooperating with the ends of the lamellae, the opposite ends of which cooperate with one of the flywheels and the others with the other of the flywheels, so that an angular movement between the flywheels causes a deflection of the lamellae in one direction for one and in the opposite direction for the other, and an angular displacement of the ring i intermediate to the steering wheel which

  is less than the angular travel between the flywheels.

  In the double damping flywheel according to the invention, the intermediate beque makes it possible to substantially double the maximum angular travel between the flywheels, since the maximum bending of the lamellae takes place in one direction between one of the flywheels and the intermediate beque and

  in the other direction between the intermediate begue and the other flywheel.

  According to another characteristic of the invention, the lamellae are gathered in groups in which they are juxtaposed in the circumferential direction and the groups of lamellae are gathered in pairs in which they are juxtaposed axially, one group of each pair cooperating with one of the steering wheels and the other cooperating pair group

with the other steering wheel.

  As a variant, the groups of lamellae are separated from each other and distributed regularly in the circumferential direction, each group cooperating with one of the flywheels and the next group cooperating

with the other of the steering wheels.

  In a first embodiment of the invention, the strips are fixed by embedding their radially external ends on

  the intermediate begue, which is then located radially around the slats.

  In this case, the radially internal ends of the lamellae are free and cooperate by abutment with elements integral with one

  of the ruffles and the others of the other ruffles.

  In another embodiment of the invention, the strips are fixed by embedding their radially external ends, the one

  on one of the steering wheels and the others on the other of the steering wheels.

  In this embodiment, the radially internal ends of the lamellae are free and cooperate by abutment with elements which are carried by said intermediate ring, the latter then being located radially.

inside the slats.

  In the two abovementioned embodiments, the elements which cooperate with the ends of the lamellae comprise cams or rollers, the cams having a substantially semi-circular convex contour or in a pointed shape, the rollers being mounted for rotation about axes.

  parallel to the axis of rotation of the flywheels.

  In a variant, each element cooperating with the free end of the blades comprises two rollers juxtaposed in circumferential direction and mounted for rotation about axes parallel to the axis of

steering wheel rotation.

  This allows in particular to use rollers of smaller diameter

  and reduce the radial size.

  Advantageously, the free ends of the strips are covered with a material resistant to wear and to temperature rises, especially when these free ends are intended to

cooperate with cams.

  In another alternative embodiment, the lamellae juxtaposed circumferentially in each group deviate from each other at

  their free ends in the rest position.

  This allows in particular to support the outer slats of each group with little pre-stress on cams or rollers

  and remove any play in the rest position.

  According to yet another characteristic of the invention, the strips are fixed by embedding on a radially external cylindrical surface by means of spacers force-fitted between the groups of strips. These spacers are advantageously with a convex outer surface, with for example a warhead shape made up of two arcs of

  circle, and form stops limiting the bending of the lamellae.

  According to yet another characteristic of the invention, the intermediate ring comprises two axially juxtaposed rings and springs with circumferential action which are mounted in windows of these two begues to oppose by elastic compression a

  angular movement between the two begues.

  Preferably, this clearance between the two rings is limited by stops formed or attached to the rings. These springs are thus mounted in series with the elastically flexible strips and their deformation is added to that of the strips. The maximum angular travel between the flywheels is thus increased by the angular travel

  maximum possible between the two intermediate rings.

  The invention will be better understood and other characteristics, details and advantages of the invention will appear more clearly on reading the

  description which follows, given by way of example with reference to the drawings

  attached in which: - Figure 1 is a schematic front view of a double damping flywheel according to the invention, shown in the rest position; - Figure 2 is a schematic view in axial section of this double damping flywheel; - Figure 3 is a schematic front view of this double damping flywheel, in a position of angular movement between the flywheels; - Figure 4 is a schematic front view of an alternative embodiment of the double damping flywheel; - Figure 5 is a schematic view in axial section of the alternative embodiment of Figure 4; - Figure 6 is a partial top view of the two intermediate rings; - Figure 7 is a schematic front view of another alternative embodiment of the double damping flywheel; - Figure 8 is a schematic front view of another alternative embodiment of the double damping flywheel; - Figure 9 is a schematic view in axial section of the alternative embodiment of Figure 8; - Figure 10 is a schematic front view of yet another alternative embodiment of a double damping flywheel according to the invention; - Figures 11a, 11b, 11c and 11d are partial front views of other alternative embodiments of the double damping flywheel according to the invention; - Figure 12 is a schematic view in axial section of the

  alternative embodiment of Figure 11 c.

  We first refer to Figures 1 to 3, which represent a first

  embodiment of a double damping flywheel according to the invention.

  In this embodiment, a first flywheel 10 is intended to be fixed at the end of an engine shaft such as the crankshaft of an internal combustion engine of a motor vehicle, by means of screws 12

  which are eight in number in the example shown.

  A second flywheel 14 is centered and guided in rotation on the first flywheel 10 by means of a bearing 16 formed by a plain bearing or by a ball bearing, which in this embodiment is radially inside the screws 12 for fixing the first flywheel 10 to the motor shaft, these screws 12 being accessible through holes 18 in the second

flywheel 14.

  The first flywheel 10 carries at its outer periphery a starter ring 20 while the second flywheel 14 generally forms the reaction plate of a clutch connecting to the shaft

  input of a transmission, such as the input shaft of a gearbox.

  The two flywheels 10 and 14 are linked in rotation by means of a torsion damping device, in a known manner comprising springs or elastically deformable means and friction means making it possible to absorb and damp the vibrations, irregularities and rotational jolts transmitted by one or other of the

flywheels.

  According to the invention, this torsional damping device comprises strips 22 of steel or of another suitable material, for example of composite material, which extend substantially radially in the rest position between an intermediate ring 24 and cams 26, 28 which are secured to the first steering wheel 10 and the others secured to the second steering wheel 14. The intermediate beque 24 is centered and guided in rotation on

  the first flywheel 10, inside a cylindrical surface 30 thereof.

  This cylindrical surface 30 is formed by the internal wall of an axial flange 32 of the first flywheel 10, which extends towards the second flywheel 14 and which delimits an annular chamber in which the intermediate ring 24, the lamellae 22 are housed. , and at least one ring 36 on which the above-mentioned cams 28 are formed, the other cams 26 being able to be in one piece with the first flywheel 10 as shown in FIG. 2 or which can also, as a variant, be formed on the outer periphery

  a ring attached to the first steering wheel.

  The lamellae 22 advantageously form groups regularly distributed around the axis of rotation 38 of the two flywheels and are fixed to the intermediate ring 24 by fitting their radially external ends between spacers 40 in the form of a warhead which are applied to the ring intermediate 24 and which clamp the ends of the lamellae 22 together. Each spacer 40 has a curved base 42 resting on the intermediate ring 24 and a bent part 44 in a rounded V, formed by two arcs of the same radius joined together and at the curved base 42. The spacers 40, which make it possible to fix the strips 22 on the intermediate ring 24 with a relatively high clamping force, also form stops limiting the bending of the strips 22, as shown in FIG. 3, so that the maximum bending of the slats is done at constant radius. The maximum bending stress of each strip is constant over the entire length of the strip. The radially internal ends of the lamellae 22 are free and engaged between the cams 26, 28 consecutive, substantially without play

  circumferential as shown in figure 1.

  The lamellae 22 are gathered in groups of lamellae, the two groups of each pair being juxtaposed axially as shown in FIG. 2. In each group of lamellae, the lamellae are juxtaposed in the circumferential direction. For example, each group of strips 22 comprises from eight to fifteen strips approximately, each strip having a thickness of between 0.7 and 1 mm for example, a width

of 10 mm and a length of 80 mm.

  The free ends of the strips 22 of the first group of a pair, which are close to the first flywheel 10, are engaged between the cams 26 integral with this flywheel, while the strips 22 of the other group of the pair, close to the second flywheel 14, have their free ends engaged between the cams 28 of the ring 36 secured to the second flywheel. In operation, any angular movement between the flywheels 10 and 14 results in rotations in opposite directions of the cams 26 and of the cams 28 integral with the flywheels, and in elastic bending of the lamellae 22 of the first groups in one direction and of the lamellae 22 of the second groups in the other direction, these flexions being limited by pressing on the rounded V-shaped parts 44 of the spacers 40 as shown in FIG. 3. The total angular clearance between the two steering wheels is equal to the sum of the angular clearance of the first steering wheel 10 relative to the intermediate ring 24 and the angular movement of the second flywheel 14

  relative to the intermediate ring 24.

  In practice, the maximum angular travel between the two

  ruffles can be around 60.

  The friction of the free ends of the lamellae 22 on the cams 26, 28 and of the lamellae 22 on each other make it possible to dampen the vibrations and irregularities in rotation which are the cause of the

lamellar bending 22.

  Furthermore, a sealing washer 46 fixed to a radial end face of the flange 32 of the first flywheel extends between the second flywheel 14 and the groups of lamellae 22 and comprises an external annular part covering the lamellae 22 and a part radially internal ring applied to a small washer secured to the second flywheel 14, the friction of this washer 46 and the washer secured to the second flywheel

  participating in the damping of vibrations and irregularities in rotation.

  In a manner known per se, the second flywheel 14 is produced in two annular parts, the radially external annular part being centered on the radially internal annular part which is itself centered with the ring 36 on the first flywheel 10 by the bearing 16, the two parts of the second flywheel 14 being joined by a torque limiter 48 formed by an elastic washer integral with the radially internal annular part and

  frictionally applied to the radially outer annular part.

  It will be noted that the cams 26 integral with the first flywheel are in radial alignment with the screws 12 for fastening on the motor shaft, for reasons of ineffectiveness. Holes 50 are formed in the begue 36 secured to the second flywheel 14, in alignment with the holes 18 of this

  second handwheel, to allow access to the heads of the screws 12.

  Advantageously, the ring 36 is secured to the second flywheel 14 by the screws 52 for fixing the elastic washer 48 of the limiter.

  torque on the radially internal annular part of the second flywheel 14.

  In the embodiment shown in Figures 4 to 6, the torsion damping device has substantially the same structure as that described with reference to Figures 1 to 3, but the intermediate begue 24 is formed of two axially juxtaposoes rings 54 and 56, which are movable in rotation relative to each other. In each group of strips 22, the strips of the first series associated with the first flywheel are fixed by embedding their radially external ends on the first ring 54, while the strips 52 of the second series, associated with the second flywheel 14, are fixed by embedding their

  radially outer ends on the second ring 56.

  The relative rotation of the two rings 54 and 56 is limited by helical springs 58 of short length, which are oriented circumferentially and regularly distributed around the axis of rotation 38 of the flywheels, each spring 58 being inside two spacers 40 axially aligned mounted one on the ring 54 and the other on the begue 56. The spring 58 is engaged at its ends on two cylindrical end pieces 60 one of which is carried by a spacer 40 and the other by the another spacer 40. Each ring 54, 56 comprises at its radially outer periphery, teeth 62 oriented axially towards the other ring and cooperating with each other to define a maximum angular clearance between the rings 54 and 56, slightly less than the angular clearance

  corresponding to maximum compression of the springs 58.

  In this embodiment, the springs 58 are in series with the blades 22 and the angular movement between the two flywheels corresponding to the maximum bending of the blades 22 is increased by

  angular clearance between the two rings 54 and 56.

  In the alternative embodiment shown in Figure 7, we find the structure already described with reference to Figures 1 to 3, and the free ends of the lamellae 22 of each series are covered with a sleeve 64 of a wear-resistant material and during heating, the sleeves 64 being for example of a plastic material limiting the friction on the

cams 26 and 28 above.

  More generally, greasing or lubrication means are provided to reduce the friction between the circumferentially juxtaposed lamellae and the friction of the ends of the lamellae on the cams 26, 28. It is possible, for example, to use a dry grease of the molybdenum disulphide type. , or a grease of a conventional type (with sealing means ensuring confinement of the grease on the lamellae). The slats can also be subjected to a treatment of

  surface reducing the aforementioned friction.

  In the alternative embodiment of FIGS. 8 and 9, these cams are replaced by rollers 66, 68 mounted for free rotation around axes parallel to the axis 38 of rotation of the flywheels, the rollers 66 being carried by

  the first flywheel 10 and the rollers 68 being carried by the second flywheel 14.

  For the rest, the structure is identical to that already described.

  In the alternative embodiment of FIG. 10, the lamellae 22 of each series in each group are slightly divergent at their free ends, to come into abutment with a slight prestress on the bases of the cams 26, 28 intended to cooperate with them. In this way, any circumferential clearance between the blades 22 and the cams 26 is eliminated.

  or 28 in the rest position of the torsion damping device.

  In the variant embodiments shown in FIGS. 11 and 12, the structure described above is inverted to the extent that the elastic strips 22 are fixed at their radially external ends to the flywheels 10 and 14, while their radially internal ends cooperate with a stop with cams or pebbles carried by a begue

  intermediate 70 which is located radially inside the lamellae 22.

  This intermediate ring 70 can be formed with cams 72 as shown in FIG. 11a, the radially internal ends of the lamellae

  22 then being engaged between two consecutive cams 72.

  As a variant, as shown in FIG. 11b, the cams are replaced by rollers 74 which are preferably double axially aligned rollers, mounted for rotation about axes parallel to the axis of rotation of the flywheels and carried by radial flanges 76 of the intermediate ring 70 which then has a U-shaped section and which can be formed

advantageously of a folded sheet.

  In the alternative embodiment of FIG. 11c, the rollers 74 are each replaced by two small rollers 78 juxtaposed in circumferential direction. Each small roller 78 of a pair of circumferentially juxtaposed rollers 78 is in abutment on or in the immediate vicinity of the free ends of the strips 22. In the alternative embodiment of FIG. 11d, stop means formed by a small additional roller or by a curved rim 82 of the intermediate ring are provided between the two small rollers 78 of an aforementioned pair to retain the free ends of the strips 80 in their maximum bending position. In this position, the support of the ends of the strips on the curved edge 82

is accompanied by friction.

  In the embodiments presented in Figures 11 and 12, the intermediate ring 70 has, due to its small diameter, a lower inertia than that of the beque 24 of the previous embodiments, its centering is ensured with reduced friction, its rigidity is greater and its deformations weaker, and it is easier to apply a force to it

  axial elastic by means of a tightening washer.

  As before, the strips 22 are distributed into first groups of strips fixed to the first flywheel 10 and

  second groups of strips fixed to the second flywheel 14.

  The lamellae of the first groups are fixed to the first flywheel by fitting their radially external ends by means of spacers 40 of the type described above which are applied to a

  cylindrical face 84 of an end edge of the first flywheel 10.

  The lamellae 22 of the second groups can be fixed on the

  second flywheel 14 in the same way.

  As a variant, the radially external ends of the lamellae 22 of the second groups are held by a peripheral ring 86 on which is fixed an angle iron 88 of which a radial face 90 cooperates with an elastic washer 92, for example of wavy shape, clamped between a radial face of the second flywheel 14 and the wing 90 of the angle iron, this assembly forming a torque limiter between the second flywheel 14 and the pre-cut crown 86.

Claims (19)

  1 - Double damping flywheel, in particular for a motor vehicle, comprising two coaxial flywheels (10, 14), mounted to rotate one on the other by means of a bearing (16) and linked in rotation the one to the other by a torsion damping device with elastic lamellae (22) substantially radial, distributed evenly around the axis of rotation (38) of the flywheels and elastically deformed in bending during an angular movement between the flywheels (10, 14), characterized in that the torsion damping device comprises an intermediate ring (24) coaxial with the lights and free to rotate relative to the flywheels, this ring cooperating with the ends of the lamellae (22) whose opposite ends cooperate with one of the flywheels and the other with the other of the flywheels, so that an angular movement between the flywheels causes the lamellae (22) to bend in one direction for the one and in the opposite direction for theothers, and an angular displacement of the intermediate ring (24, 70) relative to the flywheels which is less than the   angular travel between the flywheels.   2 - Double damping flywheel according to claim 1, characterized in that the strips (22) are gathered in groups in which they are juxtaposed in circumferential direction and in that the groups of strips form pairs in which they are axially juxtaposed, a group of lamellae of each pair cooperating with one   steering wheels and the other group of the pair cooperating with the other steering wheel.   3 - Double damping flywheel according to claim 1 or 2, characterized in that it comprises a sealing washer (46) extending radially between the lamellae (22) and one (14) of the flywheels, this washer being fixed to one of the flywheels and cooperating by friction with a   washer attached to the other flywheel.   4 - Double damping flywheel according to one of claims   previous, characterized in that the intermediate begue (24, 70) is centered and guided in rotation on a cylindrical surface of one of the flywheels (10,14)   - Double damping flywheel according to one of the claims   previous, characterized in that the strips (22) are fixed by embedding their radially outer end on said begue intermediate (24).   6 - Double damping flywheel according to one of claims 1 to 4,   characterized in that the cells (22) are fixed by embedding at their radially external end, one on a handwheel (10) and the other on the other flywheel (14).   7 - Double damping flywheel according to claim 6, characterized in that the lamellae (22) cooperating with the second flywheel (14) by their radially external ends are connected to this flywheel by a limiter couple (86, 88, 90, 92).   8 - Double damping flywheel according to claim 5, characterized in that the radially internal ends of the strips (22) are free and cooperate by abutment with elements (28, 66) integral with each other   one of the frills and the others of the other frills.   9 - Double damping flywheel according to claim 6 or 7, characterized in that the radially internal ends of the lamellae (22) cooperate by abutment with elements (72, 74, 78, 80, 82) carried by said intermediate begue (70).   - Double damping flywheel according to claim 8 or 9, characterized in that said elements (28, 66, 72, 74, 78) comprise cams or rollers.   11 - Double damping flywheel according to one of claims 8 to   , characterized in that said elements are arranged between the groups of lamellae (22), in contact with or in the immediate vicinity of the ends radially internal of the lamellae.   12 - Double damping flywheel according to one of claims 8 to   11, characterized in that the elements are cams (26, 28, 72) with   convex outline substantially semi-circular or pointed.   13 - Double damping flywheel according to one of claims 8 to   11, characterized in that the elements are rollers mounted for rotation   about an axis parallel to the axis (38) of rotation of the flywheels.   14 - Double damping flywheel according to one of claims 8 to   11, characterized in that said elements comprise rollers (78) juxtaposed in circumferential direction and mounted in rotation around   axes parallel to the axis of rotation of the flywheels.   - Double damping flywheel according to all of claim 9 and claim 13 or 14, characterized in that the axes of rotation of the rollers (74,78) are carried by the intermediate ring (7o). 16 - Double damping flywheel according to claim 14, characterized in that the intermediate beque (70) has a U-shaped section   open to the outside and made of sheet metal.   17 - Double damping flywheel according to one of claims   previous, characterized in that the lamellae (22) are fixed by embedding on a radially external cylindrical surface by means   spacers (40) forcibly mounted between the groups of lamellae.   18 - Double damping flywheel according to claim 17, characterized in that the spacers (40) have an outer surface   convex and form stops limiting the bending of the lamellae (22).   19 - Double damping flywheel according to claim 18, characterized in that the spacers (40) have in cross section a   ogive shape made up of two arcs of circle of the same radius.   - Double damping flywheel according to one of the claims   previous, characterized in that said intermediate ring comprises two rings (54,56) axially juxtaposed and springs (58) with circumferential action are mounted between these two rings to oppose by   elastic compression at an angular clearance between the rings.   21 - Double damping flywheel according to claim 20, ca characterized in that the angular movement between the two rings is limited by stops (62) formed or attached to the begues. 22 - Double damping flywheel according to all of claim 2 and claim 20 or 21, characterized in that, in each pair of lamella groups, those associated with one of the flywheels are fixed by embedding on the one (54) of said rings and those associated with the other of the flywheels are fixed by embedding on the other (56) of said rings.   23 - Double damping flywheel according to one of claims 2 to   22, characterized in that the free ends of the lamellae of each group are covered with a sleeve (64) of wear-resistant material and warming up.   24 - Double damping flywheel according to one of claims 1 to   22, characterized in that, in each group, the circumferentially juxtaposed lamellae deviate from each other at their free ends.   25 - Double damping flywheel according to one of claims   previous, characterized in that the lamellae (22) are made of steel or