Vibration damper, associated damping mechanism and propulsion assembly
11118652 · 2021-09-14
Assignee
Inventors
- Benoit Fleche (Amiens, FR)
- Fabien Lebeau (Amiens, FR)
- Jerome Boulet (Amiens, FR)
- Carlos Lopez Perez (Fuenlabrada, ES)
Cpc classification
F16F2230/0064
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16F15/1333
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16F15/1428
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F16F15/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A vibration damper is provided with two rotating members, i.e. an oscillating inertial flywheel and a member to be damped driven by a torque following a torque path between a driving member and a driven member, wherein the inertial flywheel is connected kinematically to the torque path between the driving member and the driven member solely by way of the member to be damped. Connecting modules between the two rotating members permit a relative angular displacement θ between the two rotating members on the two sides of a reference relative angular position. Each connecting module is provided with a roller associated with a first of the two rotating members and a cam track connected resiliently by a resilient element to a second of the two rotating members.
Claims
1. A vibration damper, of inertial beater type, comprising: two rotating members guided rotationally around an axis of revolution, wherein one of the two rotating members is an inertial flywheel oscillating around the axis of revolution and the other of the two rotating members is a member to be damped, wherein the member to be damped is arranged to be driven by a torque following a torque path between a driving member and a driven member, wherein the inertial flywheel is arranged to be connected kinematically to the torque path between the driving member and the driven member solely by way of the member to be damped; and one or more connecting modules between the two rotating members, permitting a relative angular displacement θ between the two rotating members around the axis of revolution on the two sides of a reference relative angular position, wherein each connecting module includes: a roller associated with a first of the two rotating members, and a cam track connected resiliently by a resilient element to a second of the two rotating members, and wherein the resilient element is capable of being deformed to ensure resilient bracing of the cam track against the roller, thus permitting the roller to roll over the cam track when the two rotating members are rotating relative to one another on the two sides of the reference position.
2. A vibration damper according to claim 1, wherein the resilient element is arranged such that the stiffness of the resilient element increases when the speed of rotation of the vibration damper increases.
3. A vibration damper according to claim 1, wherein a resilient strip constitutes the resilient element, the resilient strip including a fixation portion fixed on the second of the two rotating members, and a flexible portion capable of flexing to ensure resilient bracing of the cam track against the roller, thus permitting the roller to roll over the cam track when the two rotating members are rotating relative to one another on the two sides of the reference position.
4. A vibration damper according to claim 3, wherein the flexible portion includes an intermediate deformation portion connecting the fixation portion to the cam track.
5. A vibration damper according to claim 4, wherein the intermediate deformation portion is U-shaped in a plane perpendicular to the axis of revolution.
6. A vibration damper according to claim 4, wherein the flexible portion is circumferentially curved around the axis of rotation extending up to a free end arranged to be displaced with a radial component when the two rotating members are rotating relative to one another.
7. A vibration damper according to claim 1, wherein the cam track is turned radially toward the exterior and toward the roller.
8. A vibration damper according to claim 1, wherein the resilient element is arranged in such a way as to permit displacement of the cam track having a radial component when the two rotating members are rotating relative to one another.
9. A vibration damper according to claim 1, wherein the roller is a roller pivoting around an axis of rotation fixed relative to the first rotating member.
10. A vibration damper according to claim 1, wherein a stop limits the angular displacement between the two rotating members.
11. A vibration damper according to claim 1, wherein the one or more connecting modules include at least two connecting modules disposed symmetrically relative to the axis of revolution.
12. A vibration damper according to claim 1, wherein in the reference relative position, the roller is braced against a zone of the cam track orthoradial relative to the reference axis.
13. A vibration damper according to claim 1, wherein the connecting module or modules are such that, when the member to be damped is rotating at a speed of revolution ω, the connecting module or modules generate together, between the two rotating members, a resultant torque Γ.sub.R of restoration toward the reference position, which is a function of the angular displacement θ between the two rotating members and of the speed of revolution co, and such that:
14. A damping mechanism comprising: an input member; an output member connected by a kinematic torque-transmission train; and a vibration damper according to claim 1, wherein the member to be damped is constituted by the input member, the output member or an element of the kinematic transmission train between the input member and the output member, wherein the oscillating flywheel is disposed in branched manner relative to the kinematic torque-transmission train.
15. A torque converter comprising a vibration damper according to claim 1.
16. A torque converter, comprising: a vibration damper of the inertial beater type, the vibration damper including: two rotating members guided rotationally around an axis of revolution, wherein one of the two rotating members is an inertial flywheel oscillating around the axis of revolution and the other of the two rotating members is a member to be damped, wherein the member to be damped is arranged to be driven by a torque following a torque path between a driving member and a driven member, wherein the inertial flywheel is arranged to be connected kinematically to the torque path between the driving member and the driven member solely by way of the member to be damped; and one or more connecting modules between the two rotating members, permitting a relative angular displacement θ between the two members rotating around the axis of revolution on the two sides of a reference relative angular position, wherein each connecting module includes: a cam follower associated with a first of the two rotating members, and a cam track connected resiliently by a resilient element to a second of the two rotating members, wherein the resilient element is capable of being deformed to ensure resilient bracing of the cam track against the cam follower, thus permitting the cam follower to be displaced over the cam track when the two rotating members are rotating relative to one another on the two sides of the reference position.
17. A torque converter according to claim 16, wherein the torque converter includes springs arranged between an input member and an output member, and the member to be damped is the input member.
18. A torque converter according to claim 16, wherein the torque converter includes springs arranged between an input member and an output member, and the member to be damped is the output member.
19. A torque converter according to claim 16, wherein the cam follower is a roller mounted to move rotationally while rolling on the cam track or a roller arranged between the cam track and the first rotating member in order to roll both on the cam track and the first rotating member when the two rotating members are rotating relative to one another.
Description
BRIEF DESCRIPTION OF THE FIGURES
(1) Other characteristics and advantages of the invention will become apparent upon reading the description hereinafter with reference to the attached figures, wherein:
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(16) For greater clarity, the identical or similar elements are marked by identical reference symbols on all figures.
DETAILED DESCRIPTION OF EMBODIMENTS
(17)
(18) The structure of double damping flywheel 22 and of vibration damper 30 is illustrated in detail in
(19) Oscillating inertial flywheel 32, guided rotationally relative to secondary flywheel 26 by a sliding bearing 48, is disposed between cover 38 and platen 42.
(20) Secondary inertial flywheel 26 is provided with a hub, in the interior of which roller bearing 46 is fitted and on the exterior of which sliding bearing 48 is fitted.
(21) Advantageously, oscillating inertial flywheel 32 is provided with a sheet-metal disk stamped in such a way as to form on its central part a cylindrical part parallel to the axis of revolution and supported by bearing 48. An annular mass may be fixed on the outside diameter of this disk to increase the inertia.
(22) Connecting modules 34 connecting oscillating inertial flywheel 32 to secondary flywheel 26 are two in number and each comprises a roller 50 mounted to move rotationally around a rod 51 in order to rotate, relative to secondary flywheel 26, around an axis of rotation 200 parallel to axis of revolution 100 and situated at a distance from this latter, and a resilient strip 52 provided with an end portion 54 fixed to oscillating inertial flywheel 32 by rivets 55. Rolling bearings of ball or needle type may be placed between rod 51 and roller 50 to favor rolling. The resilient strip is additionally provided with a flexible portion comprising a guide portion or cam 56, which forms a cam track 58 situated radially in the interior of roller 50, i.e. between roller 50 and axis of revolution 100, and braced on roller 50, and an intermediate resilient deformation portion 59. Stops (not visible in the figures) limit the possible angular displacement between oscillating inertial flywheel 32 and secondary flywheel 26 on the two sides of a reference relative position, in which roller 50 is in contact with a zone of cam track 58, referred to as reference zone or equilibrium zone, which is orthoradial relative to axis of revolution 100, i.e. is tangential, in a plane perpendicular to axis of revolution 100 and to axis of rotation 200, to a perpendicular to a radial axis passing through axis of revolution 100 and axis of rotation 200. The reference position therefore corresponds to a zero torque transmitted between secondary flywheel 26 and the oscillating inertial flywheel, and is so independently of the speed of rotation, since the contact forces transmitted between roller 50 and cam track 58 in the reference position are purely radial.
(23) The curvature of cam track 58 on the two sides of the reference position is such that the normal to the point of contact of cam track 58 with roller 50 has an orthoradial component oriented toward the reference position, which increases when the angular displacement θ relative to the reference position increases. While rolling over cam track 58 on the two sides of the reference position, roller 50 causes resilient strip 52 to flex in the region of intermediate deformation portion 59. In this way it is ensured that the contact between roller 50 and cam track 58 generates, on oscillating inertial flywheel 32 and on secondary flywheel 26 respectively, two opposed torques, around axis of revolution 100, that tend to restore oscillating inertial flywheel 32 and secondary flywheel 26 toward the reference position.
(24) The torque of restoration toward the reference position, transmitted by the interaction between roller 50 and cam track 58 to secondary flywheel 26, which here constitutes the member to be damped, will be considered in the following. Resilient strip 52 has a flexural stiffness such that, even when stopped, the restoring force has a resilient component Γ.sub.1 of restoration toward the reference relative position, which is a function of the angular displacement θ between the two rotating members 26, 32. To a first approximation, disregarding the deformations of resilient strip 52 as a function of the speed of revolution, it may be considered that this resilient component Γ.sub.1 is relatively independent of the speed of revolution and, as the case may be, may be estimated when stopped.
(25) Furthermore, resilient strip 52 has an inertia which, when resilient strip 52 is rotating at a speed of revolution ω, generates a centrifugal force on roller 50, such that the restoring force has an inertial component Γ.sub.2 of restoration toward the reference relative position, which is a function of the angular displacement θ between the two rotating members 26, 32 and of the speed of revolution ω.
(26) The two components Γ.sub.1 et Γ.sub.2, which have been described separately here and for each connecting module 34 are added to generate, globally, a resultant torque Γ.sub.R, which is exerted on secondary flywheel 26 and which may be measured on a test bench by making secondary flywheel 26 and oscillating inertial flywheel 32 rotate at a given speed of revolution ω and then measuring the torque necessary to maintain a given angular displacement θ.
(27) To make the behavior of vibration damper 30 approach that of a pendulum with a good degree of approximation, the stiffness of resilient strip 52 and the slope of cam track 58 are chosen in such a way that the resultant torque Γ.sub.R is, with a good degree of approximation, proportional to the angular displacement θ at given speed of revolution ω in a speed range lying between a predetermined minimal value ω.sub.min lower than 1000 rpm and a predetermined maximal value ω.sub.max higher than 1500 rpm, and proportional to the square of the speed of revolution to for a given angular displacement θ in the range of possible angular displacements. In this particular case, a positive constant C is defined, such that the following relationship is satisfied in the speed range between ω.sub.min and ω.sub.max:
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(29) It is then possible to define an apparent stiffness K of the vibration damper 30 equal to the quotient of the resultant torque Γ.sub.R over the corresponding angular displacement θ, wherein this stiffness K is substantially proportional to the square of the speed of revolution ω and such that:
¾Cω.sup.2≤K≤5/4Cω.sup.2
(30) For every given speed of revolution ω in the speed range between the range of speeds between ω.sub.min and ω.sub.max, vibration damper 30 behaves as a pendulum with a resonance oscillation frequency F.sub.V, which is a function of the apparent stiffness K and of the inertia I of oscillating inertial flywheel 32. To a first degree of approximation, this stiffness K is related to the resonance oscillation frequency F.sub.V and to the moment of inertia of oscillating inertial flywheel 32 by a simple equation of the type:
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(32) The filtering mechanism must be matched to the torque fluctuations that are supposed to be attenuated. As it happens, it is known that the main frequency of acyclic irregularity of an engine depends on the type of engine 12 and especially on the number of cylinders. Thus, for a four-stroke engine 12 and thus one ignition per cylinder every two revolutions of crankshaft 14, the main acyclic irregularity frequency F.sub.M generally corresponds to the frequency of ignition of the cylinders, i.e., for an N-cylinder engine and for a given speed of revolution ω of crankshaft 14, to:
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(34) By matching the resonance frequency of oscillation of vibration damper 30 to the main acyclic irregularity frequency F.sub.M(ω) of engine 12, it is possible, for a range of speeds of revolution, for vibration damper 30 to beat in phase opposition relative to the acyclic irregularities, leading to a large attenuation of the vibratory level. Rotating member 26 connected to crankshaft 14 is therefore subjected to antagonistic torques in phase opposition that compensate one another at least partly, i.e. on the one hand an input acyclic torque originating from crankshaft 14, and on the other hand an oscillating torque transmitted by connecting modules 34. To obtain the desired matching between the resonance frequency of oscillation of vibration damper 30 and the main acyclic irregularity frequency, the possibility that connecting module 34 according to the invention offers is advantageously used to vary, by means of the profile of the cam tracks, the law relating the angular displacement θ between the two rotating members 26, 32 and the transmitted torque.
(35) In this particular case, a value ω.sub.0 is defined in the range of speeds of revolution between ω.sub.min and ω.sub.max, such that the main acyclic irregularity frequency of the engine coincides with the resonance oscillation frequency Fv of vibration damper 30, as expressed by:
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(37) Vibration damper 30 does not permit this perfect equality to be obtained for the entire range of speeds of revolution between ω.sub.min and ω.sub.max, and the observed divergence increases with distance from the matching value ω.sub.0. In this sense, vibration damper 30 is less efficient than an oscillating pendulum. Nevertheless, the vibration-attenuation performance remains very interesting and is obtained with particularly simple means.
(38) Vibration damper 30 according to the invention may be disposed at different positions in propulsion assembly 10, as illustrated, for example, in
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(43) In a manner similar to the first embodiment, each connecting module 34 is provided with a roller 50 rolling on a cam track 58 formed on a resilient strip 52. Roller 50 is mounted here on first rotating member 26 in such a way that it is able to rotate freely around an axis of rotation 200 parallel to axis of revolution 100 and is situated at a distance from axis of revolution 100, wherein axis of rotation 200 is materialized by a rod 51 and by a sliding or roller bearing 70 interposed between rod 51 and roller 50. Resilient strip 52 has a shape curved back on itself as a U, one branch of which constitutes an end portion 54 fixed to second rotating member 32 and the other branch of which forms cam track 58, wherein both branches 54, 58 are connected by a deformable bent part 59 curved back on itself. Second rotating member 32 here is in two pieces 72, 74, between which resilient strips 52 are disposed, wherein the two pieces 72, 74 are fixed to one another by rivets 55 passing through resilient strips 52. First rotating member 26 itself is formed by a flywheel 76, on which a sleeve 78 is welded, wherein guide bearing 48 is fitted onto sleeve 78 and in a tubular part of piece 74 of second rotating member 32. 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 rotating members 26, 32 is reached. These stops are formed on the one hand by an axial extension of one of the pieces of second rotating member 32 rotating around axis 100 and on the other hand by the upturned edge of a window of first rotating member 26.
(44)
(45) This embodiment is distinguished from that represented in
(46) According to this embodiment, the inertial flywheel is provided with an annular sheet-metal plate 83 and an inertial ring gear 65 fixed radially on the exterior of this annular sheet-metal plate. Annular sheet-metal plate 83 is disposed in a plane perpendicular to axis of rotation 100. In this case, strips 52a and 52b and the annular sheet-metal plate are formed in a single piece.
(47) In fact, the flexible portion of the flexible strips is formed by means of a cut made in the annular sheet-metal plate. This cut makes it possible to obtain the exterior contour of flexible portions 58 of strips 52a and 52b. The strips are connected to the annular sheet-metal plate by way of a base 85.
(48) In this case, each base 85 is stamped in such a way that each strip 52a and 52b is offset axially relative to annular sheet-metal plate 83 of inertial flywheel 32. Thus, by virtue of base 85, each strip 52a, 52b is capable of flexing in a plane parallel to the plane in which annular sheet-metal plate 83 is disposed. Thus the cut made to form the flexible strip portion is able globally to follow the shape that is supposed to be given to the strip. Removal of material, also performed by cutting, may be carried out in the annular sheet-metal plate around the junction zone between the base and the flexible portion of strips 52a and 52b in such a way as to favor stamping.
(49) Plate 83 is also stamped radially toward the interior, in such a way as to form a mounting skirt 87. A bearing 48 arranged between this mounting skirt 87 and a hub of secondary inertial flywheel 42 ensures that inertial flywheel 32 can be mounted with the ability to rotate relative to secondary inertial flywheel 42.
(50) Thus, with this embodiment, the manufacture of strips is simplified and it is no longer necessary to resort to assembly means.
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(52) This embodiment is distinguished from that represented in
(53) In this case, strips 52a and 52b and annular sheet-metal plate 83 again are formed in a single piece. However, the strips are capable of flexing in the same plane as the plane in which annular sheet-metal plate 83 is disposed.
(54) Consequently, an indentation 88a is required radially on the exterior of the flexible portion of each strip in such a way as to permit the displacement of a roller on cam track 58 of each strip 52a, 52b.
(55) Similarly, another indentation 88b is required radially on the interior of the flexible portion of each strip, in such a way as to permit a radial displacement of the strip in the direction of axis 100 when cam roller 50 is displaced on cam track 58.
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(57) In this case, the vibration damper is therefore integrated in a torque converter 60. Here, input member 24 is connected to oscillating inertial flywheel 32 by way of connecting modules 34, which together form an oscillating mechanism.
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(59) On the one hand, input member 24 is composed of guide disks 24a and 24b arranged axially on the two sides of springs 28 and 29.
(60) On the other hand, input member 24 is composed on a support element 24c formed in a sheet-metal plate. This sheet-metal support plate 24c carries connecting modules 34. Resilient strips 52a and 52b of the module are mounted on sheet-metal support plate 24c.
(61) In addition, input member 24 is composed of turbine hub 24d. Turbine hub 24d and first guide disk 24a are joined together, especially by means of a mounting member such as a rivet, which can be mounted along axis Z.
(62) On the other hand, sheet-metal support plate 24c is fixed on second guide disk 24b. Sheet-metal support plate 24c is likewise fixed on a connecting piece 64a of locking clutch 64. In this variant, sheet-metal support plate 24c is sandwiched between connecting piece 64a of locking clutch 64 and second guide disk 24b. Connecting piece 64a of locking clutch 64, second guide disk 24b and sheet-metal support element 24c are assembled together with fixation means such as rivets.
(63) The vibration damper is provided with a circular centering zone F around axis of rotation 100, which ensures centering of inertial flywheel 32 on sheet-metal support plate 24c. For this purpose, radially external rim 94 of sheet-metal support plate 24c is bent over to form a surface for cooperation with inertial flywheel 32. The radially external rim of sheet-metal support plate 24c forms a baffle 94 forming on the one hand a cylindrical friction surface and on the other hand an axial retaining element.
(64) Guide disks 24a and 24b are fixed to rotate with one another by virtue of an axially extending connecting lug.
(65) At the output, an output shroud 27a braced against springs 29 is fixed on an output hub 27b capable of driving a gearbox input shaft.
(66) Advantageously, the inertial flywheel has a pot shape and the springs and the guide disks are arranged in the interior of this pot.
(67) In a second variant, not illustrated, of this embodiment, the strips may be fixed on the inertial flywheel and the rollers may be mounted to move rotationally on the support element.
(68) In another embodiment, illustrated in
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(70) On the one hand, output member 27 is composed of an output shroud 27a braced against springs 29 and of an output hub 27b. The springs are circumferentially interposed between input member 24, formed by guide disks, and output shroud 27a.
(71) On the other hand, the output member is composed on a support element 27c formed in a sheet-metal plate. This sheet-metal support plate 27c carries connecting modules 34. Rollers 50 of the module are mounted to move rotationally on this sheet-metal support plate 27c.
(72) Sheet-metal support plate 27c is therefore mounted to rotate with output shroud 27a and with output hub 27b. Sheet-metal support plate 27c is likewise mounted to rotate with turbine T. In this variant, sheet-metal support plate 27c is sandwiched between one among turbine T and output hub 27b on the one hand and output shroud 27a on the other hand. In the illustrated variant, sheet-metal support plate 27c is sandwiched between turbine T and output hub 27b, and turbine T is sandwiched between sheet-metal support plate 27c and the output hub. Turbine T, output shroud 27a, output hub 27b and sheet-metal support plate 27c are riveted together with common fixation means such as rivets.
(73) The vibration damper is provided with a circular centering zone F around axis of rotation 100, which ensures centering of inertial flywheel 32 on sheet-metal support plate 24c. For this purpose, radially external rim 94 of sheet-metal support plate 24c is bent over to form a surface for cooperation with inertial flywheel 32. Radially external rim 94 of sheet-metal support plate 24c forms a baffle 94 forming on the one hand a cylindrical friction surface and on the other hand an axial retaining element.
(74) In a second variant, not illustrated, of this embodiment, the rollers may be fixed on the inertial flywheel and the strips may be mounted on the support element.
(75) Within the context of a torque converter, the cam followers may also be realized in the form of bosses capable of being displaced along the cam track.
(76) Of course, the examples represented in the figures and discussed hereinabove are provided only by way of illustration and are not limitative. It is explicitly provided that the different embodiments illustrated may be combined with one another in order to propose further embodiments. Cam track 58 and roller 50 may smooth or toothed, to ensure engagement of the rack and pinion type. Roller 50 may be unconstrained and may roll on cam track 58 formed on resilient strip 52 connected to one of the rotating members 26, 32 and another cam track 58 formed on the other rotating member, wherein the two cam tracks are facing one another, wherein cam track 58 formed on resilient strip 52 is disposed radially in the interior of the other cam track 58.
(77) Similarly, other strip shapes and geometries may be employed to realize the present invention.