WO2017072338A1

WO2017072338A1 - Vibration damper

Info

Publication number: WO2017072338A1
Application number: PCT/EP2016/076164
Authority: WO
Inventors: Benoit FLECHE; Jérôme BOULET
Original assignee: Valeo Embrayages
Priority date: 2015-10-30
Filing date: 2016-10-28
Publication date: 2017-05-04
Also published as: FR3043156B1; FR3043156A1

Abstract

The invention relates to a vibration damper (30) comprising two rotating members (26, 32) rotatably guided about one axis of rotation (100), and one or more connection modules (34) between the two rotating members (26, 32), enabling a relative angular displacement è between the two rotating members (26, 32) about the axis of rotation (100) on either side of a reference relative angular position. Each connection module (34) comprises a first connection element associated with a first (26) of the two rotating members and a second connection element associated with a second (32) of the two rotating members. One of the connection elements is a resilient blade (52) on which is formed a cam track (58), the other connection element is a roller (50) capable of rolling along the cam track (58).

Description

VIBRATION ABSORBER TECHNICAL FIELD OF THE INVENTION

The invention relates to the filtration of acyclisms of an internal combustion engine, in particular for an application to a motor vehicle, and in particular to a vibration absorber more particularly intended to be interposed between an internal combustion engine and a gearbox, and can for example be integrated in a torque converter or a clutch mechanism dry or friction. It also relates to a propulsion assembly incorporating such a vibration absorber.

In the context of the present application, a drummer type vibration absorber is a filtering mechanism arranged to be connected to a transmission chain only through the member to be damped or rotated solely by through the organ to be damped. In practice, such a damper may comprise one or more "crazy" oscillating masses connected to an element to be damped by one or more elastic elements of constant or variable stiffness, the oscillating mass or masses not being intended to be connected to other elements than the body to be damped.

STATE OF THE PRIOR ART

In order to mitigate the irregularities of rotation of an internal combustion engine crankshaft, mainly at speeds between the idling speed and an intermediate speed, for example about 2500 rpm, it has been proposed in the document FR2857073 to directly couple to the crankshaft of an internal combustion engine a flywheel attenuating torsional vibration or revolution speed fluctuations, consisting of a first mass of inertia integral with the crankshaft rotation and comprising a starter ring and a reaction plate of a friction clutch, and a second mass of inertia movable in rotation with respect to the first, by means of four articulated connection modules each comprising at least one swing arm pivoting by relative to the first mass of inertia around an axis parallel to the axis of revolution, an oscillating mass positioned at a free end of the oscillating arm so as to be mobile in a substantially radial direction, and a connecting rod connecting an intermediate point of the oscillating arm to the second mass of inertia. By centrifugal effect, the articulated modules oppose the relative rotation of the masses of inertia by exerting a return torque substantially proportional to the relative rotation of the two masses of inertia and to the square of the speed of revolution of the mass of inertia. inertia linked to the crankshaft.

The constitutive law of this flywheel provides a filter particularly optimized for a speed of revolution, and whose effect remains beneficial although not optimal over a range of revolution speed values around optimized diet. But the structure of the mechanism is complex, with several modules each requiring three pins subjected to centrifugal forces and several moving parts. It is necessary to provide a blocking of the link modules when the speed of revolution exceeds the speed of intermediate speed, to prevent the pivots are solicited beyond their mechanical strength limits. This blocking is obtained by blocks of elastomeric material, interposed between the oscillating masses and the second mass of inertia, and coming into contact with the second mass of inertia when the revolution speed exceeds the intermediate speed. These elastomer blocks increase the mechanism and can age prematurely. In addition, the mechanism is noisy in the transient phases of slowdown, when the speed of revolution is no longer sufficient.

SUMMARY OF THE INVENTION

The invention aims to overcome the disadvantages of the state of the art and to propose a simplification means for filtering the acyclisms of an internal combustion engine over a range of revolution speed values around the optimized speed.

To do this is proposed, according to a first aspect of the invention, a vibration absorber, comprising two rotating members guided in rotation about an axis of revolution, and one or more connecting modules between the two rotating members , allowing a relative angular displacement Θ between the two rotating members about the axis of revolution on either side of a reference relative angular position, each link module comprising a first connecting element associated with a first of the two rotating members and a second connecting element associated with a second of the two rotating members, one of the first and second connecting elements being a cam on which is formed a cam path, the other first and second connecting elements being a roller adapted to roll on the cam path when the two rotating members rotate relative to each other on either side of the reference position, characterized in that each connecting module comprises elastic connection means between the second connecting element and the second rotating member, allowing a radial displacement of the second connecting element relative to the second rotating member, and keeping the second connecting element in abutment against the first connecting element, the second connecting element having a center of mass located at a distance from the axis of revolution, so that when the second connecting element rotates at a revolution speed ω, the link module or modules generate together between the two rotating members a resulting torque T _R of return to the reference position, a function of the angular displacement Θ between the two rotating members and the revolution speed ω, and such that:

where C is a given positive constant, when the revolution speed ω varies in a speed range between a predetermined minimum value û _m m less than 1000 rpm and a predetermined maximum value w _max greater than 1500 rpm. By thus combining an elastic return effect and a return effect by inertia, in judiciously chosen proportions, we obtain a return torque substantially proportional to the square of the speed of revolution and the angular displacement between the two rotating members, which is to say that the connection module or modules generate between the two rotating members an apparent stiffness substantially proportional to the square of the revolution speed. It is indeed possible to define an apparent stiffness K of the vibration absorber, equal to the quotient of the resulting torque T _R by the corresponding angular deflection,, this stiffness K being such that:

The choice of a rolling connection between the roller and a cam path also allows to minimize friction. By construction, the elastic connection means maintain contact between the roller and the cam path in all operating modes, thus also at rest, which eliminates the sudden noises with the mechanisms of the state of the prior art .

It may be envisaged that the second connecting element comprises the roller. Alternatively, and preferentially because in practice simpler implementation, the second connecting element is the cam.

It may be envisaged that the elastic connection means are constituted by one or more parts separate from those of the second connecting element, for example by one or more springs urging the second connecting element. Alternatively, and preferably and particularly advantageously, the vibration absorber comprises an elastic blade attached to the second rotating member, and comprising the cam and the elastic means. This gives the desired effect with a very small number of parts, including a particularly low number of moving parts. Preferably, the elastic blade comprises a fixing portion fixed to the second rotating member, and a flexible portion, the flexible portion comprising a guide portion comprising the cam and on which is formed the cam path and an intermediate portion of deformation, connecting the fixing portion to the guide portion and constituting the elastic connection means. The intermediate portion of deformation concentrates the constraints. According to one embodiment, the intermediate deformation portion is U-shaped. This configuration makes it possible to take advantage of the available volume around the axis of revolution, so as to maximize the amplitude of the radial displacement of the suspended connection element.

Preferably, the first connecting element is disposed radially outside the second connecting element. Thus, the first connecting element radially maintains the second connecting element when it is subjected to the centrifugal force. According to a preferred embodiment, the roller is a roller pivoting about a fixed axis of rotation relative to the rotating member associated with the roller.

It can be provided that a stop limits the angular movement between the two rotating members. Preferably, the connection module or modules comprise at least two connection modules, preferably identical, and preferably arranged symmetrically with respect to the axis of revolution. The symmetry allows a balancing of the rotating masses. It is possible to provide a number of connection modules greater than two, for example three connection modules arranged at 120 ° or four connection modules arranged at 90 °.

Preferably, the reference relative position, the roller bears against an area of the orthoradial cam path relative to the reference axis. In the reference position, the return torque is zero because the forces transmitted between the cam path and the roller are purely radial. The reference position is a position of stable equilibrium of the mechanism, and this for all speeds of rotation.

One of the rotating members is preferably arranged to be driven by a driving torque and to transmit a driving torque of a member leading to a driven member. The other of the rotating members is arranged to be in derivation with respect to the path taken by the engine torque. In practice, one of the two rotating members is an oscillating flywheel having a moment of inertia / with respect to the axis of revolution and the other of the two rotating members is a member to be damped, damping member being provided with means for mechanical connection to a driving member and to a driven member, the oscillating flywheel being devoid of means for mechanical connection to a driving member or to a driven member. The mechanical connection may be constituted by means for fixing in rotation and in translation (for example holes for the passage of fixing rods) or in rotation only (for example a grooved cavity) and / or by elastic means, in particular by means of springs connecting the organ to be damped to the driving member and / or the driven member. Preferably, the vibration absorber is devoid of friction damping means dissipating energy when the two rotating members rotate relative to each other on either side of the position of reference. Indeed, the mechanism is intended to function as a pendulum, and not as a dissipating damper of energy.

It is known that the main harmonic of an engine acyclism depends on the type of engine and in particular the number of cylinders. Thus, for a four-stroke engine, and thus a combustion per cylinder every two crank turns, the main frequency of FM acyclism generally corresponds to the combustion frequency of the cylinders, ie for a N-cylinder engine and for a speed of revolution ω of the given crankshaft: ω

By tuning the oscillation resonance frequency of the vibration absorber to the main frequency of FM motor acyclism [C], for a range of revolution speeds, the vibration absorber is allowed to beat. in opposition of phase compared to the acyclisms, from where a significant attenuation of the vibratory level. The rotary member connected to the crankshaft is thus biased by opposing pairs in phase opposition which compensate themselves at least partially, namely on the one hand an acyclic input torque from the crankshaft, and on the other hand a torque oscillating transmitted by the link modules. To obtain the desired agreement between the oscillation resonance frequency of the vibration absorber and the main frequency of acyclism, we take advantage of the possibility offered by the rolling connection module according to the invention. to vary, with the profile of the raceways, the law connecting the angular displacement between the two rotating members to the transmitted torque. Thus, according to a particularly advantageous embodiment, the connection module or modules are shaped so that the resulting torque TR of return towards the reference position, is such that for at least one speed of predetermined revolution ω ₀ less than 1000 rpm and at least one integer N equal to 1, 2, 3, 4, 5, 6, 7 or 8, in particular 3, 4 or 6, there is observed:

[0022] Preferably:

[0023] The mechanism so defined is therefore particularly suitable for filtering the frequency ω ₀ / 2Ν, which typically corresponds to the cyclic disturbance frequency of a four-stroke engine N cylinders rotating at a speed ω _0.

According to another aspect of the invention, it relates to a vibration absorber comprising two rotating members guided in rotation about an axis of revolution and one or more rotational connection modules between the two bodies. rotating, allowing a relative angular displacement Θ between the two rotating members on either side of a reference relative angular position, each connecting module having two connecting elements, each of the two connecting elements being associated with one of the two rotating members, one of the two connecting elements being a cam path formed on an elastic blade, the other of the two connecting elements comprising a roller adapted to roll on the cam path by moving the cam path radially. relative to the rotary member associated elastically deforming the elastic blade when the two rotating members rotate relative to each other on both sides of the position of reference, the elastic blade having a center of gravity located at a distance from the axis of revolution, so that when the elastic blade rotates at a revolution speed ω, the connection module or modules generate together between the two rotating members a pair resulting return T _R to the reference position, function of the angular displacement Θ between the two rotating members and the revolution speed ω, and such that:

where C is a given positive constant, when the revolution speed ω varies in a speed range between a predetermined minimum value û _m m less than 1000 rpm and a predetermined maximum value w _max greater than 1500 rpm.

According to another aspect of the invention, it relates to a propulsion assembly comprising a four-stroke internal combustion engine and N cylinders having a crankshaft rotating about an axis of revolution, characterized in that it further comprises a vibration absorber as described above, one of the two rotating members of the vibration absorber being an oscillating flywheel having a moment of inertia / with respect to the axis of revolution and the other of the two rotating members of the vibration absorber being a member to dampen driven by the crankshaft, or the connecting modules being shaped so as to generate together between the two rotating members a resulting torque T _R of return to the reference position, a function of the angular displacement Θ between the two rotating members and the revolution speed ω, and such that, for at least one predetermined revolution speed ω ₀ lower at 1000 rpm and at least one integer N equal to 1, 2, 3, 4, 5, 6, 7 or 8, in particular 3, 4 or 6, there is observed:

[0026] Preferably:

Preferably, the propulsion assembly further comprises a gearbox, and the member to be damped is arranged in series between the crankshaft and the gearbox, the oscillating flywheel being kinematically connected only 'to the organ to be damped. According to one embodiment the damping member is a secondary flywheel of a double damping flywheel or a long-stroke damper, or a phasing washer of a long-stroke damper.

In practice, the oscillating flywheel is disposed in shunt relative to the transmission chain connecting the crankshaft and the gearbox. In other words, the rotating member constituting the member to be damped is arranged to be driven by a driving torque and to transmit a driving torque of a member leading to a driven member. The other of the rotating members, which constitutes the oscillating flywheel, is arranged in derivation with respect to the path taken by the engine torque.

The invention also relates to a vibration absorber, comprising two rotating members guided in rotation about an axis of revolution, and one or more connecting modules between the two rotating members, allowing a relative angular movement Θ between the two members rotating around the axis of revolution on either side of a reference relative angular position, each connecting module comprising a first connecting element associated with a first of the two rotating members and a second connecting element associated with a second of the two rotating members, one of the first and second connecting elements being a cam on which is formed a cam path, the other of the first and second connecting elements being a roller adapted to roll on the road of cam when the two rotating members rotate relative to each other on either side of the reference position, characterized in that each module of connection comprises means for elastic connection between the second connecting element and the second rotating member, allowing a radial displacement of the second connecting element relative to the second rotating member, and maintaining the second connecting element bearing against the first connecting element the vibration absorber having, when the second connecting element rotates at a revolution speed ω, an apparent stiffness K substantially proportional to the square of the revolution speed ω such that: C being a given positive constant.

According to one embodiment, C is a given positive constant, when the revolution speed ω varies in a speed range between a predetermined minimum value û _m m less than 1000 rpm and a predetermined maximum value w _max greater than 1500 rev / min.

BRIEF DESCRIPTION OF FIG RES

Other features and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: FIG. 1, a schematic view of a propulsion assembly according to one embodiment of the invention, comprising a double flywheel incorporating a vibration absorber; Figure 2 is a perspective view of a portion of the double flywheel of the propulsion assembly of Figure 1; Figure 3 is a sectional view of the double flywheel of Figure 2; Figure 4, a front view of a portion of the double flywheel of Figure 2; Figure 5 is a schematic view of a propulsion assembly according to another embodiment of the invention; Figure 6 is a schematic view of a propulsion assembly according to another embodiment of the invention; Figure 7 is a schematic view of a propulsion assembly according to another embodiment of the invention; Figure 8 is a perspective view of a vibration absorber according to another embodiment of the invention; Figure 9 is a perspective view of an interior portion of the vibration absorber of Figure 8; FIG. 10 is a sectional view of the vibration absorber of FIG. 8.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

In Figure 1 is shown a set of propulsion 10 of a motor vehicle comprising an internal combustion engine 12 whose crankshaft 14 drives a transmission kinematic chain 16 having a dry clutch 18 located upstream of an input shaft 20 gearbox. Cinematically between the crankshaft 14 and the clutch 18 friction in the kinematic transmission chain 16 is disposed a damping mechanism 22 constituting a double damping flywheel 22 and having an input member consisting of a primary flywheel 24 integral with the crankshaft 14 and an output member constituted by a secondary flywheel 26 integral with a reaction plate of the clutch 18 or being one piece therewith. Elastic members 28 are interposed between the input member and the output member so as to work during angular positioning fluctuations between primary flywheel 24 and secondary flywheel 26. A vibration absorber 30 according to the invention, comprising a oscillating flywheel 32 disposed in shunt relative to the kinematic chain connecting the crankshaft 14 to the gearbox, and connecting modules 34 connecting the oscillating flywheel 32 to the secondary flywheel 26, allows attenuation of the vibrations to Low speed of the secondary flywheel 26. The crankshaft 14, the damping mechanism 22, the clutch 18 and the input shaft 20 of the gearbox rotate around the same axis of revolution 100.

The structure of the double damping flywheel 22 and the vibration absorber 30 is illustrated in detail in Figures 2 to 4. The primary flywheel 24 is composed of a plate 36 and a cover 38 fixed one to the other, between which are arranged coil springs constituting the elastic members 28 and a web 40 of the secondary flywheel 26. The secondary flywheel 26 further comprises a solid plate 42 fixed to the web 40 by rivets 44, which also forms the reaction plate of the friction clutch 18. A rolling bearing 46 provides guidance in rotation of the secondary flywheel 26 relative to the primary flywheel 24. Between the cover 38 and the plate 42 is disposed the oscillating flywheel 32, guided in rotation relative to the secondary flywheel 26 by a sliding bearing 48.

The secondary flywheel 26 has a hub inside which is fretted the rolling bearing 46 and outside which is fretted the sliding bearing 48.

Advantageously, the oscillating flywheel 32 comprises a disk made of sheet metal so as to form on its central portion a cylindrical portion, parallel to the axis of revolution, and supported by the bearing 48. An annular mass may be fixed on the outer diameter of this disc to increase the inertia. The connecting modules 34 connecting the oscillating flywheel 32 to the secondary flywheel 26 are two in number and each comprises a roller 50 mounted on a mobile rotation about a rod 51 to rotate relative to the secondary flywheel 26 around an axis of rotation 200 parallel to the axis of revolution 100 and located at a distance from the latter, and an elastic blade 52 having an end portion 54 fixed to the oscillating flywheel 32 by rivets 55. elastic blade further comprises a flexible portion comprising a guide portion or cam 56 which forms a cam path 58 located radially inside the roller 50, that is to say between the roller 50 and the axis of revolution 100, and bearing on the roller 50, and an intermediate portion of elastic deformation 59. Stops (not visible in the figures) limit the possible angular movement between the oscillating flywheel 32 and the secondary flywheel 26, from else of a relative reference position, wherein the roller 50 is in contact with a zone of the cam path 58, said reference zone or equilibrium zone, which is orthoradial with respect to the axis of revolution 100, that is to say ie which, in a plane perpendicular to the axis of revolution 100 and to the axis of rotation 200, is tangential to a perpendicular to a radial axis passing through the axis of revolution 100 and the axis of rotation 200. reference position therefore corresponds to a zero torque transmitted between the secondary flywheel 26 and the flywheel, regardless of the speed of rotation since the forces in contact between the roller 50 and the cam path 58 in the position reference are purely radial. The curvature of the cam path 58 on either side of the reference position is such that the normal at the point of contact of the cam path 58 with the roller 50 has an orthoradial component oriented towards the reference position, which increases when the angular displacement Θ relative to the reference position increases. By rolling on the cam path 58, on either side of the reference position, the roller 50 bends the elastic blade 52 at the intermediate deformation portion 59. This ensures that the contact between the roller 50 and the cam path 58 generates respectively on the oscillating flywheel 32 and on the secondary flywheel 26 two opposite couples around the axis of revolution 100, tending to recall the oscillating flywheel 32 and the secondary flywheel 26 to the reference position.

We will consider in the following the restoring torque to the reference position, transmitted by the interaction between the roller 50 and the cam path 58 to the secondary wheel 26, which is here the body to be damped. The elastic blade 52 has a stiffness in flexion, so that, even at rest, the restoring torque has an elastic component Γι of return towards the reference relative position, a function of the angular displacement Θ between the two rotating members 26, 32. As a first approximation, by neglecting the deformations of the elastic blade 52 as a function of the speed of revolution, it can be considered that this elastic component Γι is relatively independent of the revolution speed, and can if necessary be estimated at stop.

Furthermore, the elastic blade 52 has an inertia which, when the elastic blade 52 rotates at a revolution speed ω, generates a centrifugal force on the roller 50, so that the return torque has a component Γ ₂ of inertial return to the reference position, function of the angular displacement Θ between the two rotating members 26, 32 and the revolution speed ω.

The two components Γι and Γ ₂ that are here described separately and for each connection module 34, add together to generate a total resulting torque T _R exerted on the secondary flywheel 26, which can be measured on a test bench by rotating the secondary flywheel 26 and the oscillating flywheel 32 to a given speed of revolution ω, and by measuring the torque necessary to maintain a given angular deflection Θ.

For the behavior of the vibration absorber 30 is close to that of a pendulum with a good degree of approximation, we choose the stiffness of the elastic blade 52 and the slope of the cam path 58 so as to that the resulting torque TR is, with a good degree of approximation, proportional to the angular displacement Θ at revolution speed ω given in a speed range between a predetermined minimum value û _m m less than 1000 rpm and a predetermined maximum value w _max greater than 1500 rpm, and proportional to the square of the revolution speed ω for an angular displacement Θ given in the range of possible angular displacements. In the present case, it is ensured that there exists a constant C positive, such that in the speed range between û) _m m and w _max :

It is then possible to define an apparent stiffness K of the vibration absorber 30, equal to the quotient of the resultant torque TR by the corresponding angular deflection,, this stiffness K being substantially proportional to the square of the revolution speed ω and such that :

For any given speed of revolution ω in the speed range between the speed range between û _m m and (ù _max , the vibration absorber 30 behaves like a pendulum having an oscillation resonance frequency F _v function of the apparent stiffness K and the inertia I of the oscillating flywheel 32. At a first degree of approximation, this stiffness K is related to the oscillation resonance frequency F _v and to the moment of inertia the oscillating flywheel 32 by a simple equation of the type:

The filtering mechanism must be tuned to the torque fluctuations that we seek to mitigate. However, it is known that the main frequency of motor acyclism depends on the type of engine 12 and in particular the number of cylinders. Thus, for a four-stroke engine 12, and thus to a combustion per cylinder every two crankshaft revolutions 14, the main frequency of FM acyclism generally corresponds to the combustion frequency of the cylinders, ie for a N-cylinder engine and for a speed of revolution ω of the crankshaft 14 given:

By tuning the oscillation resonance frequency of the vibration absorber 30 to the main frequency of FM acyclism [C] of the motor 12, for a range of revolution speeds, the vibration absorber is allowed. 30 to beat in phase opposition with respect to acyclisms, resulting in a significant attenuation of the vibratory level. The rotating member 26 connected to the crankshaft 14 is thus biased by opposing pairs in phase opposition which compensate themselves at least partially, namely on the one hand an acyclic input torque, from the crankshaft 14, and on the other hand The oscillating torque transmitted by the connecting modules 34 is proportional to the desired agreement between the oscillation resonance frequency of the vibration absorber 30 and the main frequency of acyclism. the connection module 34 according to the invention to vary, with the profile of the cam paths, the law connecting the angular deflection Θ between the two rotating members 26, 32 and the transmitted torque.

In this case, it is ensured that for a value ω ₀ in the revolution speed range between œ _min and o½ _ax , the main motor acyclic frequency coincides with the oscillation resonance frequency Fv vibration absorber 30, which results in:

The vibration absorber 30 does not allow to obtain this perfect equality for the entire range of revolution speeds between œ _min and o½ _ax , and the divergence observed increases when one moves away from the agreement value ω ₀ . In this sense, the vibration absorber 30 is less efficient than an oscillating pendulum. However, the vibration attenuation performance remains very interesting, and is obtained with particularly simple means. The vibration absorber 30 according to the invention may be disposed at different locations in the propulsion assembly 10, as illustrated for example in Figures 5 to 7.

In Figure 5, there is shown schematically a vibration absorber 30 according to the invention, mounted in shunt on a primary flywheel 24 of a double damping flywheel 22.

FIG. 6 illustrates a self-contained vibration absorber 30 mounted directly on the crankshaft 14 of the internal combustion engine 12, possibly at one end of the crankshaft 14 opposite the clutch 18.

FIG. 7 schematically illustrates a propulsion assembly 10 comprising an internal combustion engine 12 and a transmission kinematic chain 16 comprising a torque converter 60 located between a crankshaft 14 of the internal combustion engine 12 and a gearbox input shaft 20. This torque converter 60 comprises in known manner a hydrokinetic converter 62 and a locking clutch 64 arranged in parallel between the crankshaft 14 and an input member 24 of a damping mechanism 22 whose output member 27 is integral with the input shaft 20 of the gearbox. An intermediate phasing member 26 is interposed in series between the input member 24 and the output member 27, connected to the input member 24 by a first elastic member 28 and the output member 27 by a second elastic member 29. This intermediate member is further connected to an oscillating flywheel 32 through connecting modules 34 forming an oscillating mechanism.

In Figures 8 to 10 is illustrated a vibration absorber 30 according to another embodiment of the invention, adapted for example to an autonomous assembly as envisaged in Figure 6 or a mounting between a double damping flywheel 22 and a clutch 18 friction. This mechanism comprises a first rotating member 26 around an axis of revolution 100, a second rotating member 32 around the axis of revolution 100, a rolling bearing 48 for guiding between the first rotating member 26 and the second rotating member 32 two connecting modules 34 allowing a relative angular displacement between the two rotating members 26, 32 and stops 66 limiting this relative angular displacement.

Each connecting module 34 comprises, in a similar manner to the first embodiment, a roller 50 rolling on a cam path 58 formed on an elastic blade 52. The roller 50 is here mounted on the first rotating member 26 so that able to freely rotate around an axis of rotation 200 parallel to the axis of revolution 100 and located at a distance from the axis of revolution 100, the axis of rotation 200 being materialized by a rod 51 and by a plain bearing or with a bearing 70 interposed between the rod 51 and the roller 50. The elastic blade 52 has a curved shape on itself in U, one branch of which constitutes an end portion 54 fixed to the second rotating member 32 and the other leg form the cam path 58, the two branches 54, 58 being connected by a deformable bent portion 59 curved on itself. The second rotating member 32 is here in two parts 72, 74 between which the elastic blades 52 are arranged, the two parts 72, 74 being fixed to each other by rivets 55 passing through the resilient blades 52. The first member turn 26 is formed by a flywheel 76 on which is welded a sleeve 78, the guide bearing 48 being shrunk on the sleeve 78 and in a tubular portion of the part 74 of the second rotating member 32. The stops 66 are constituted by surfaces of the two rotating members 26, 32 which come into contact when the limit of relative angular displacement between the two rotary members 26, 32 is reached. These stops are formed on the one hand by an axial extension of one of the parts of the second rotating member 32 rotating about the axis 100 and secondly by the rim of a window of the first rotating member 26.

Naturally, the examples shown in the figures and discussed above are given for illustrative and not limiting. It is explicitly provided that the different embodiments illustrated for to propose others. The cam path 58 and the roller 50 may be smooth or toothed to provide a rack and pinion type meshing. The roller 50 can be free and roll on the cam path 58 formed on the elastic blade 52 connected to one of the rotating members 26, 32 and another cam path 58 formed on the other rotating member, the two paths of cam being opposite each other, the cam path 58 formed on the elastic blade 52 being disposed radially inside the other cam path 58.

Similarly, other shapes and geometries of blades can be implemented to achieve the present invention.

Claims

Vibration absorber (30), comprising two rotating members (26, 32) guided in rotation about an axis of revolution (100), and one or more connecting modules (34) between the two rotating members (26, 32). ), allowing a relative angular displacement Θ between the two rotating members (26, 32) around the axis of revolution (100) on either side of a reference relative angular position, each connecting module (34) comprising a first connecting element associated with a first (26) of the two rotating members and a second connecting element associated with a second (32) of the two rotating members, one of the first and second connecting elements being a cam (56); ) on which is formed a cam path (58), the other of the first and second connecting elements being a roller (50) adapted to roll on the cam path (58) when the two rotating members (26, 32) turn relative to each other on either side of the posi reference system, characterized in that each connection module (34) comprises elastic connection means (59) between the second connecting element (56) and the second rotating member (32), allowing a radial displacement of the second element of connection (56) with respect to the second rotating member (32), and maintaining the second connecting element (56) bearing against the first connecting element (50), the second connecting element (56) having a center of mass located away from the axis of revolution (100), so that when the second link member (56) rotates at a revolution speed ω, the link module or modules generate together between the two rotating members (26, 32). a resulting torque TR of return towards the reference position, function of the angular displacement Θ between the two rotating members (26, 32) and the revolution speed ω, and such that:

3 Γ _κ 5

- C≤ - <- C

4 θ - ω ² 4

where C is a given positive constant, when the revolution speed ω varies in a speed range between a predetermined minimum value û _m m less than 1000 rpm and a predetermined maximum value û _m ax greater than 1500 rpm .

Vibration absorber according to claim 1, characterized in that the second connecting element (56) is the cam (56).

3. Vibration absorber (30) according to claim 2, characterized in that it comprises a resilient blade (52) fixed to the second rotating member, and having the cam (56) and the elastic means (59).

4. Vibration absorber (30) according to claim 3, characterized in that the elastic blade (52) comprises a fixing portion (54) attached to the second rotating member (32), and a flexible portion, the flexible portion comprising a guide portion comprising the cam (56) and on which is formed the cam path (58) and an intermediate deformation portion (59), connecting the fixing portion (54) to the guide portion (56) and constituting the elastic connection means (59).

Vibration absorber (30) according to claim 4, characterized in that the intermediate deformation portion (59) is U-shaped.

Vibration absorber (30) according to one of the preceding claims, characterized in that the first connecting element (50) is arranged radially outside the second connecting element (56).

7. Vibration absorber (30) according to any one of the preceding claims, characterized in that the roller (50) is a roller pivoting about an axis of rotation (200) fixed relative to the rotating member (26). ) associated with the roller (50).

8. vibration absorber (30) according to any one of the preceding claims, characterized in that a stop (66) limits the angular movement between the two rotating members (26, 32). Vibration absorber (30) according to one of the preceding claims, characterized in that the connection module or modules (34) comprise at least two connecting modules (34), preferably identical, and preferably symmetrically arranged. relative to the axis of revolution (100).

Vibration absorber (30) according to any one of the preceding claims, characterized in that in the relative reference position, the roller (50) bears against an area of the cam path (58) orthoradial with respect to the reference axis (100).

Vibration absorber (30) according to any one of the preceding claims, characterized in that one of the two rotating members (26, 32) is an oscillating flywheel (32) having a moment of inertia / relative to to the axis of revolution (100) and the other of the two rotating members (26, 32) is a damping member (26), the damping member (26) being provided with mechanical connection means to a driving member and a driven member, the oscillating flywheel (32) being devoid of means for mechanical connection to a driving member or to a driven member.

Vibration absorber (30) according to one of the preceding claims, characterized in that the vibration absorber (30) is free of energy-dissipating friction damping means when the two rotary members (26, 32 ) rotate relative to each other on either side of the reference position.

Vibration absorber (30) according to any one of the preceding claims, characterized in that the connection module or modules (34) are shaped in such a way that the resulting resting torque TR towards the reference position is such that for at least one predetermined revolution speed ω _{0 of} less than 1000 rpm and at least one integer number N equal to 1, 2, 3, 4, 5, 6, 7 or 8, in particular 3, 4 or 6, observed:

and preferably:

Propulsion unit (10) comprising an internal combustion engine (12) (50) with four times and N cylinders comprising a crankshaft (14) rotating about an axis of revolution (100), characterized in that it comprises furthermore a vibration absorber (30) according to any one of claims 1 to 10, one of the two rotating members (26, 32) of the vibration absorber (30) being an oscillating flywheel (32). ) having a moment of inertia / with respect to the axis of revolution (100) and the other of the two rotating members (26, 32) of the vibration absorber (30) being a damping member (26) driven by the crankshaft (14), the one or more connecting modules (34) being shaped so as to generate together between the two rotating members (26, 32) a resultant torque TR of return towards the reference position, a function of the angular displacement Θ between the two rotating members (26, 32) and the revolution speed ω, and such that, for at least one speed with a predetermined revolution ω _{0 of} less than 1000 rpm and at least one integer N equal to 1, 2, 3, 4, 5, 6, 7 or 8, in particular 3, 4 or 6, there is observed:

and preferably:

A propulsion unit (10) according to claim 14, further comprising a gearbox, characterized in that the damping member is arranged in series between the crankshaft (14) and the gearbox, the oscillating flywheel (32) being kinematically linked to the organ to be damped. A propulsion unit (10) according to claim 14 or claim 15, characterized in that the member to be damped is a secondary flywheel of a double damping flywheel or a long-stroke damper, or a phasing washer of a long stroke damper.

Propulsion unit (10) according to any one of claims 14 to 16, further comprising a gearbox, characterized in that the oscillating flywheel is arranged in shunt relative to the transmission chain connecting the crankshaft ( 14) and the gearbox.