Improved damping group

Abstract

A damping assembly (F) comprising a filtering pulley (1) including a hub (2) designed to be fixed to a shaft rotating around a longitudinal axis (A), a crown (3) mounted coaxially and so as to freely rotate on the hub (2), at least one filtering assembly operatively interposed between the crown (3) and the hub (2), the crown (3) defining a first annular wall (5' ' ) provided with a profile (6) configured to engage an endless transmission element of a vehicular system, the first annular wall (5'') being carried by a connecting wall (9) operatively connected to the filtering assembly, the damping assembly (1) comprising a torsional damper (30) carried by said hub (2) and housed in a space (35) delimited by the hub (2), the connecting wall (9) and the first annular wall (5''), the connecting wall (9) defining a plurality of openings (40) configured to allow air to flow through the connecting wall (9) and said space (35) and a plurality of protuberances (41) associated with the plurality of openings (40).

Description

[0001] "IMPROVED DAMPING GROUP"

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This Patent Application claims priority from Italian Patent Application No. 102023000026475 filed on December 12, 2023, the entire disclosure of which is incorporated herein by reference.

[0004] TECHNICAL FIELD

[0005] The invention relates to an improved damping assembly, preferably for a pulley for a crankshaft in an accessory transmission of an internal combustion engine.

[0006] KNOWN STATE OF THE ART

[0007] As it is known, the drive shaft of internal combustion engines is subjected to torsional vibrations due to periodic stresses caused by the combustion taking place in the cylinders. Said vibrations are particularly strong when the engine is started and at low speeds as well as in the presence of particular constructive solutions, such as for example the use of dual-clutch transmissions or start-stop systems.

[0008] Torsional vibrations translate into irregularities in the rotation of he drive pulley of the accessory transmission, which are transmitted to the accessories through the transmission belt, which, therefore, is subjected to periodic tension vibrations. It is therefore known, in the automotive industry, to reduce the amplitude of the torsional vibrations of the drive shaft through the use of filtering assemblies provided with dampers coupled to filtering pulleys, which are distinguished based on their operating principle, namely based on the means that is used to damp the vibrations.

[0009] Much used in the past in engines for motor vehicles were dampers of torsional friction vibrations, which, in broad terms, consist a flywheel that is caused to rotate by the drive shaft through a clutch coupling; thanks to its high moment of inertia, the flywheel tends to assume a constant speed of rotation, consequently damping, by means of the friction, any torsional vibrations of the drive shaft.

[0010] For applications with higher specific power and for uses in motor vehicles there are provided dampers that use an elastic material or a viscoelastic fluid as a damping means, whose operating principles are similar to the one mentioned above. In the case of viscoelastic fluid dampers, the coupling between the drive shaft and the flywheel is obtained through the interposition of a viscous means, typically silicone fluid.

[0011] This fluid is inserted into a space housing a rotating element / flywheel and delimited by a cup-shaped portion and by a disc rigidly connected to the cup-shaped portion. With regard to filtering pulleys, it is known to provide various types thereof, as it is known for example from EP 3271616 Al.

[0012] During its use, the rotating element tends to heat the fluid housed in the cup-shaped portion, thus limiting the use of the damper or requiring a design such as to increase its size, weight and, hence, costs.

[0013] Solutions are known, shown for example in DE1020108691 Al, in which fins made on the outer wall of the cup facilitate, during rotation, the exchange of heat with the outside. However, it is clear that these solutions increase the production costs of the damper and increase the noise thereof, thus limiting its energy efficiency.

[0014] Alternatively, it is known to provide openings provided with blades, as shown in DE102021106830 B3, obtained on a portion of a filtering pulley adjacent to the damper and configured to facilitate the passage of an air flow towards the cup-shaped portion of the damper so as to cool it. In this case, again, the production of blades increases the production costs and the noise of the damping assembly.

[0015] The object of the invention is to provide a filtering pulley capable of solving the aforementioned technical problem in a simple and economic fashion.

[0016] In particular, the object is to provide a damping assembly that allows the damper to be maintained within a predetermined temperature range without, however, increasing its dimensions, weight and costs, as is the case in known systems.

[0017] SUMMARY OF THE INVENTION

[0018] The aforesaid object is reached by a damping assembly according to the appended claims that are an integral part of this description.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will be best understood upon perusal of the following detailed description of a preferred embodiment, which is provided by way of non-limiting example, with reference to the accompanying drawings, wherein:

[0021] • Figure 1 is a perspective view of a filtering assembly according to the invention;

[0022] • Figure 2 is an exploded perspective view of the filtering assembly of figure 1;

[0023] • Figure 3 is a first sectional perspective view of the filtering assembly of figure 1;

[0024] • Figure 4 is a first diametral sectional view of the filtering assembly of figure 1;

[0025] • Figure 5 is a second diametral sectional view of the filtering assembly of figure 1; and

[0026] • Figure 6 is a second sectional perspective view of the filtering assembly of figure 1.

[0027] DETAILED DESCRIPTION OF THE INVENTION

[0028] Figures 1 to 4 show a filtering assembly F provided with a filtering pulley 1 comprising a hub 2 with axis A, which is designed to be connected to a shaft (which is not shown herein), for example a crankshaft of an internal combustion engine, and an annular crown 3, which is externally coaxial to the hub 2 and is supported by the hub 2 through support means 4 so that it can freely rotate.

[0029] The crown 3 comprises a first and a second annular portion 5', 5'’, each provided with a profile 6 designed to cooperate with an endless transmission element of a vehicular system, such as a poly-V belt (not shown) of an accessory transmission.

[0030] In particular, the first and second annular portion 5', 5'’ are arranged at a different radial distance from the hub 2 and are connected to one another by a connecting wall 9, which is substantially radial with respect to the axis A.

[0031] The crown 3 carries, integral to it, a cup-shaped element 7 comprising an outer cylindrical wall 7' configured to cooperate in contact with the first annular portion 5', a radial annular wall 7'', advantageously having a shaped form and extending from the outer cylindrical wall 7'' towards the hub 2, and an inner cylindrical wall ’’’ connected to the radial wall 7'' on the side opposite the outer cylindrical wall 7’.

[0032] Advantageously, the inner cylindrical wall j’’’ cooperates in contact with the aforementioned support means 4.

[0033] The crown 3 carries, integral to it, a closing element 11 comprising an outer cylindrical wall 11' with axis A, a radial annular wall 11'', advantageously having a shaped form and extending from the wall 11' towards the hub 2. In the embodiment described herein, the closing element 11 is inserted into the cup-shaped element 11 so as to form an annular chamber 12, which is radially comprised between the cylindrical walls 7'’’, 11' and is axially delimited by the radial walls 11'', 7’’.

[0034] The closing element 11 and / or the cup-shaped element 7 further define two diametrically opposite projections 13, which axially extend into the chamber 12 starting from the respective radial walls 7'', ll''. The projections 13 divide the chamber 12 into two preferably equally sized portions.

[0035] These projections 13 are carried by the respective walls 7'', 11'' in a fixed manner or, alternatively, are manufactured as one single piece together with them.

[0036] The pulley 1 further comprises a filtering assembly operatively interposed between the hub 2 and the crown 3 and configured to filter the vibrations transmitted between the hub 2 and the crown 3.

[0037] In particular, in the embodiment described herein, the filtering assembly comprises at least one elastic assembly 20, for example two elastic assemblies 20, which are arched and are arranged circumferentially free in the respective portions of the chamber 12 delimited by the projections 13.

[0038] Each one of the elastic assemblies 20 comprises at least one spring, in the case described herein a helical and arched spring 21 mounted between the aforementioned projections 13.

[0039] The pulley 1 also comprises an actuator 22 carried by the hub in an integral manner, in the embodiment described herein advantageously manufactured as one single piece together with the hub 2.

[0040] The actuator 22 has two spokes 23, which are free to circumferentially move in the chamber 12, thus passing between the cup-shaped element 7 and the closing element 11, and are designed to interact with the elastic assembly 20 through contact, as described below.

[0041] The actuator 22 can be brought into contact with the elastic assemblies 20, possibly with a circumferential interference value so as to pre-load the elastic assemblies 20 inside the seat 12. Alternatively, it can be placed within an angular range with respect to the elastic assemblies 20, i.e. with an angular clearance before coming into contact with them.

[0042] The pulley 1 further comprises a dust-proof lip 25 configured to avoid contamination from the outside of the rotating support 4 between the hub 2 and the crown 3.

[0043] Advantageously, the dust-proof lip is located between a flange 11''' of the closing element 11 extending terminally with respect to the radial annular wall 11'' and a head element 26 integral to the hub 2.

[0044] The damping assembly F further comprises a torsional damper 30 rigidly carried by the hub 2 and, therefore, acting in parallel to the pulley 1.

[0045] Advantageously, said torsional damper 30 is a viscous damper.

[0046] In particular, said torsional damper 30 comprises a disc 31 defining, radially on the outside of the hub 2, a chamber 32 designed to house a rotating ring 33 sliding therein.

[0047] Indeed, the chamber 32 is designed to house a viscous fluid, of a type known in the industry, designed to counter the movement of the rotating ring 33.

[0048] It should be pointed out, in particular, that the torsional damper 30 is housed in a space radially delimited by the hub 2 and by the second annular portion 5'’, axially delimited, on one side, by the connecting wall 9 and by the radial annular wall 7'' of the cup-shaped element 7 and open on the opposite side.

[0049] In the embodiment shown herein, the disc 31 is connected to the hub 2 by means of threaded elements / pins.

[0050] Advantageously, as shown herein, the hub 2 is divided into a plurality of portions 2', 2'’, 2’’’. A first portion 2’ is manufactured as one single piece together with the actuator 22 and supports the support means 4, a second portion 2’’ supports the disc 31 of the torsional damper 30 and a third portion 2’’’ supports the head element 26.

[0051] The three portions of the hub 2 are advantageously connected to one another by means of threaded elements / pins, preferably designed, at the same time, to fix the hub 2 on the crankshaft. To this aim, the three portions 2 define through openings 36 designed to enable the aforementioned fixing.

[0052] Advantageously, the connecting wall 9 defines a plurality of openings 40 configured to allow air to flow towards the space 35.

[0053] In detail, the openings 40 go through the connecting wall 9. In detail, the opening angle of the openings 40 is parallel to the axis A or can be inclined with respect to it. In particular, the cut of the openings can vary in inclination along the perimeter of the openings 40, so as to facilitate the passage of air inside them. In detail, the circumferential perimeter edges of the openings could have an opposite inclination, so as to facilitate the inlet of air in any direction of rotation.

[0054] In particular, the openings 40 are cut into the connecting wall 9 without defining protuberances along their perimeter, on one side and on the other side of the connecting wall 9. Basically, the perimeter of the openings 40 is coplanar to the surface of the connecting wall 9.

[0055] Advantageously, the openings 40 are angularly spaced apart from one another around the axis A, in particular evenly spaced apart from one another. Advantageously, the openings 40 have the same shape.

[0056] Preferably, the openings 40 have a polygonal shape, advantageously a quadrangular and flared shape so that a radially inner portion with respect to the axis A has a smaller angular extension than a radially outer portion. Therefore, in the embodiment shown herein, the openings 40 substantially have the shape of a isosceles trapezoid, in particular with rounded vertices.

[0057] Advantageously, in the annular band of connecting wall 9 affected by the openings 40, at least half of the surface of said annular band is occupied by the openings 40.

[0058] Preferably, furthermore, the connecting wall 9 carries a plurality of protuberances 41 extending from the connecting wall 9 and associated with the openings 40. In particular, said protuberances 41 extend from the connecting wall 9 on the side opposite the space 35.

[0059] Advantageously, said protuberances 41 are circumferentially interposed between two openings 40. Preferably, said protuberances 41 are radially more on the inside, i.e. less spaced apart from the hub 2, with respect to the axis A of the openings 40.

[0060] In detail, the protuberances 41 are manufactured as bumps, namely through deformation, in the connecting wall 9, hence they are manufactured as one single piece together with it.

[0061] In addition, said protuberances 41 are advantageously obtained at the junction between the connecting wall 9 and the first radial wall 5'.

[0062] Preferably, said protuberances 41 have the shape of a truncated pyramid, i.e. they comprise an axial wall 41', inclined with respect to a plane defined by vertical and transverse axes (perpendicular to the longitudinal axis A) of the damping assembly F, and a pair of circumferential walls 41'', also advantageously inclined with respect to a plane defined by the longitudinal axis A and by the aforementioned vertical axis.

[0063] As best shown in figures 5 and 6, the connecting wall 9 comprises an inclined portion 9' at the junction with the first annular wall.

[0064] Advantageously, the inclination of said inclined portion 9' is constant around the axis A. Even more advantageously, the protuberances 41 are obtained in the area of said inclined portion 9'.

[0065] In particular, the axial wall 41' of the protuberances 41 is more inclined than the inclined portion 9' of the connecting wall 9, thus radially extending to a greater extent than the latter.

[0066] Consequently, in the circumferential direction, the inclined portion 9' is discontinuous due to the presence of the protuberances 41, i.e. it changes inclination due to the radial wall 41'’ and axial wall 41' thereof.

[0067] The operation of the pulley 1 is described below.

[0068] In a first operating step, called "driving mode" and constituting the normal operation of the damping assembly F, when the drive shaft drives the accessories, the speed of the hub 2 tends to exceed the speed of the crown 3. For this reason, the spokes 23 of the actuator 22 transmit the torque to the projections 13 with the interposition of the respective elastic assemblies 20.

[0069] This also happens, in a symmetrical manner, in the "overrunning" condition, namely when the speed of the crown 3 tends to exceed the speed of the hub 2.

[0070] In parallel, the damper 30 acts thanks to the inertia of the annular element 33 housed in the space 32 with respect to the disc 31 so as to dampen the vibrations occurring on the hub 2. During this parallel action, the damper 30 tends to heat up due to the friction between the annular element 33 and the fluid contained in the space 32.

[0071] During the rotation, the openings 40 permit the passage of air in the space 35, enabling a quick cooling of the damper 30.

[0072] This air passage effect is reinforced by the particular section of the openings 40. Furthermore, this effect is reinforced by the protuberances 41, which direct the air towards the openings 40 thanks to the radial walls 41'’.

[0073] Therefore, the advantages of a damping assembly F according to the invention are evident.

[0074] Thanks to the presence of the openings 40, it is possible to allow air to flow towards the damper 30, allowing it to cool down during operation.

[0075] Since the openings 40 are mere openings in the connecting wall 9 of the crown 3, i.e. they do not include fins or blades, there is no increase in noise during the rotation of the damping assembly and, moreover, the production costs thereof are reduced compared to prior art solutions.

[0076] In addition, the particular geometry of the openings permits a large passage of air inside the space 32.

[0077] In particular, the shape suggested herein makes it easier for air to flow into the space 35, especially if the edges thereof are inclined with respect to the longitudinal axis in terms of opening cut.

[0078] The presence of protuberances 41 allows, first of all, for an increase in the structural strength of the connecting wall 9, a large surface thereof being occupied by the openings 40.

[0079] In this way, it is possible, at the same time, to make large air passage openings, without the need to provide fins or blades to facilitate the entry of air, thus reducing the weight of the crown 3, in particular maintaining an adequate thickness and, therefore, reducing the manufacturing cost.

[0080] This effect is further increased thanks to the presence of the inclined portion 9', which further increases the strength of the crown 3.

[0081] In detail, since the inclined portion 9' and the protuberances 41 can be manufactured by means of a press, the production of the crown 3 is particularly cost-effective.

[0082] Furthermore, the protuberances 41, thanks to the fact that they have the shape of a truncated-pyramid, whose circumferential walls 41'’ are inclined, facilitate the orientation of the air flow during the rotation of the damping assembly 1 towards the openings 40.

[0083] In this way, the entry of air into the openings 40 is facilitated, though without providing the pulley 1 with fins or blades.

[0084] Finally, the damping assembly described above can be subjected to changes or variants, which do not go beyond the scope of protection set forth in the appended claims.

[0085] First of all, the pulley does not necessarily have to be used on the crankshaft of an internal combustion engine, but it could be used for one of the accessories thereof.

[0086] In particular, although a particular structure of the filtering pulley 1 is described, it is clear that any type of filtering pulley could be used so as to provide a torque filtering between the hub 2 and the crown 3.

[0087] In addition, the damper could be manufactured in a different type and with other geometries.

[0088] Similarly, the geometry of the first and second annular wall 5', 5'’ could be different, as could that of the openings 40 and the protuberances 41.

Claims

CLAIMS1.- Damping assembly (F) comprising a filtering pulley (1) including a hub (2) configured to be fixed to a shaft rotating around a longitudinal axis (A), a crown (3) mounted coaxially and rotationally free on said hub (2), at least one filter assembly operationally interposed between said crown (3) and said hub (2), said crown (3) defining a first annular wall (5'') provided with a profile (6) configured to engage an endless transmission element of a vehicular system, said first annular wall (5'') being carried by a connection wall (9) operationally connected to said filtering assembly, said damping assembly (1) comprising a torsional damper (30) carried by said hub (2) and housed in a space (35) delimited by said hub (2), said connecting wall (9) and said first annular wall (5 ''), said connecting wall (9) defining a plurality of openings (40) configured to allow the passage of air through said connecting wall (9) and said space (35) and a plurality of protuberances (41) extending said connecting wall (9) and associated with said plurality of openings (40).2.- Damping assembly according to claim 1, in which said openings (40) are spaced circumferentially between each other around said longitudinal axis (A), said protuberances(41) being placed circumferentially between two openings (40).3.- Damping assembly according to claim 1 or 2, wherein said protuberances (41) are radially internal with respect to said openings (40).4.- Damping assembly according to one of the previous claims, in which said protuberances (41) have a truncated pyramidal portion shape.5.- Damping assembly according to one of the previous claims, in which said protuberances (41) comprise an axial wall (41') and a pair of circumferential walls (41'').6.- Damping assembly according to one of the previous claims, in which said protuberances (41) are made in one piece with said connecting walls (9).7.- Damping assembly according to one of the previous claims, in which said connection wall (9) includes an inclined portion (9') on the opposite side of said first annular wall (5'').8.- Damping assembly according to claim 7, in which said protuberances (41) are made in correspondence with said inclined portion (9').9.- Damping assembly according to claim 8 when dependent on 5, in which said axial wall (41') has a greater inclination than said inclined portion (9').10.- Damping assembly according to one of the previous claims, in which said protuberances (41) extend from the opposite side of said space (35).11.- Damping assembly according to one of the previous claims, wherein the edges of said openings (40) are parallel to said longitudinal axis (A).12.- Damping assembly according to one of the previous claims, in which the edges of said openings (40) are inclined with respect to said longitudinal axis (A).13.- Damping assembly according to one of the previous claims, in which said crown (3) includes a second annular wall (5') carried by said connecting wall (9) on the opposite side of said first annular wall (5''), said protuberances (41) being created in correspondence with the connection of said connection wall (9) and said second annular wall (5').14.- Damping group according to any of the previous claims, wherein said filtering assembly comprises an elastic group (20) operationally interposed between first elements (22) integral with the hub (2) and second elements (13) integral with said crown (3).

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