Filtering pulley comprising a HUB provided with an improved fixation system

Abstract

Hub (2) or hub adaptor (2' ) for a filtering pulley (1), the hub (2) or hub adaptor (2' ) defining a surface (2a) adapted to co-operate in contact under axial load, at least a portion of the surface (2a) being provided with a surface processing (2b) configured to increase the friction of the surface (2a) under axial load.

Description

[0001] FILTERING PULLEY COMPRISING A HUB PROVIDED WITH AN

[0002] IMPROVED FIXATION SYSTEM

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This Patent Appl ication claims priority from Italian Patent Application No . 102024000011482 filed on May 21 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0005] TECHNICAL SECTOR

[0006] The present invention relates to a fixation system for a filtering pulley, in particular for a belt transmission of a motor vehicle internal combustion engine .

[0007] The present invention finds a preferred, though not exclusive , application to the pulley connected to the crankshaft of an internal combustion engine . This application will be referred to below by way of example , it being however clear that the pulley of the invention may be used as a pulley for any other accessory of the engine itsel f , for example a reversible electric machine with generator and engine function .

[0008] BACKGROUND OF THE INVENTION

[0009] Filtering pulleys are known to be used in motor vehicles .

[0010] This pulley comprises a hub adapted to be connected by the crankshaft , an annular crown with a profile adapted to cooperate with the belt , and a filtering unit interposed between the hub and the crown of the pulley to avoid subj ecting the belt to dynamic overloads in the presence of torsional vibrations of the crankshaft or rapid variations in motor speed .

[0011] In particular, the hub is fixed to a rotating shaft connected to the rotor of the alternator, or directly to it , by means of fixation means , such as threaded elements , such as screws .

[0012] The introduction of start-stop systems in which a reversible electric machine is used, acting as a starter motor or alternator depending on the operating conditions , increases the stresses in both the hub rotation directions .

[0013] Consequently, known fixation systems of the above- mentioned type are subj ected to increased torsion in both screwing and unscrewing directions thereof .

[0014] Thus , it is well known that the hub fixation screws can loosen from the shaft to which they are connected, generating situations of potentially serious damage and related accidents i f the hub of a filtering pulley were to decouple from the relative shaft during the vehicle operation .

[0015] There is therefore a need to provide a filtering pulley that can be used both in a start-stop system and in a conventional transmission system, which solves the problems of the known filtering pulleys outlined above .

[0016] Another obj ect o f the present invention is to realise a filtering pulley, which is compact and cost-ef fective to manufacture .

[0017] SUMMARY OF THE INVENTION

[0018] The aforementioned obj ect is achieved by a hub and a filtering pulley as claimed in the attached claims forming an integral part of the present description .

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] An embodiment is described below for a better understanding of the present invention, provided by way of non-limiting example with reference to the accompanying drawings , wherein :

[0021] • Figure 1 is a schematic section view of a pulley comprising a fixation system according to the invention;

[0022] • Figure 2 is a perspective view o f a portion of the hub comprising a first embodiment of the fixation system according to the invention; and

[0023] • Figure 3 is a perspective view of a portion integral with the hub comprising a second embodiment of the fixation system according to the invention .

[0024] DETAILED DESCRIPTION OF THE INVENTION

[0025] Figure 1 shows an exemplary filtering pulley 1 , comprising a hub 2 of axis A, adapted to be connected to a shaft (not shown) , e . g . a crankshaft of an internal combustion engine , and an annular crown 3 externally coaxial to the hub 2 and supported rotationally free on the hub 2 by means of a support element 4 .

[0026] The crown 3 comprises an annular portion 5 provided with a profile 6 adapted to cooperate with a poly-V belt (not shown) . The crown 3 further comprises a radial wall 7 , integral with the annular portion 5 and preferably in a single piece with it , extending radially towards the hub 2 , and a substantially cylindrical inner wall 8 of axis A.

[0027] The crown 3 carries , integral therewith, a closing element 11 comprising an outer cylindrical wall 12 of axis A and a flat radial annular wall 13 . The closing element 11 is fitted in the crown 3 to form an annular chamber 15 radially included between the wall 12 and the wall 8 and axially delimited by the wall 7 and the wall 13 .

[0028] Finally, the closing element 11 comprises two diametrically opposite proj ections 16 axially extending into the chamber 15 from the wall 13 ( see Figure 3 ) . The proj ections 16 divide the chamber 15 into two portions 15a, 15b, preferably of equal si ze .

[0029] On the wall 7 there are stop elements , such as two proj ections (not shown) preferably arranged at 180 ° relative to proj ections 16 , thus substantially in the middle of the respective portions of the above-mentioned chamber 15 . The proj ections 16 and the stop elements are carried fixed by the respective walls or, alternatively, are made in a single piece with them .

[0030] The pulley 1 may also be provided with a dynamic damper 19 comprising a disc 21 , facing the closing element 11 and having a hub portion 22 integral with the hub 2 , and a seismic ring 23 constrained to a perimeter flange 24 of the disc 21 by a ring 25 of elastomeric material .

[0031] As shown, the pulley 1 also comprises at least one filtering assembly 30 , e . g . , two arcuate spring assemblies arranged circumferentially free in the respective portions of the chamber 15 delimited by the proj ections 16 .

[0032] Each of the spring assemblies comprises at least one spring, in the case described, a helical and arcuate spring 31 mounted between the above-mentioned proj ections 16 .

[0033] The pulley 1 still comprises an actuator 35 that is integrally carried by the hub 2 and advantageously axially interposed between the hub 2 and the disc 21 of the dynamic damper 19 . The actuator 35 has two spokes 36 that are free to move circumferentially in the chamber 15 and adapted to interact with the spring assemblies by contact as described hereinafter . As shown in Figure 1 , the actuator 35 and the dynamic damper 19 are connected by a mechanical connection 37 to the hub 2 .

[0034] As therefore discussed above , di f ferent operating elements , such as the actuator 35 and / or the dynamic damper 19 are connected to the hub 2 by a mechanical connection 37 .

[0035] Although not shown in Figure 1 , which shows a pulley of the known type , the hub 2 could be connected to the rotating shaft by an adapter 2 ' , as for example shown in Figure 3 . This would also , in case , be connected by a mechanical connection 37 .

[0036] Figure 2 represents a further geometric shape of an above-discussed hub 2 , which will be referred to hereinafter, as well as the adapter 2 ' in Figure 3 .

[0037] The hub 2 defines a surface 2a configured to cooperate under axial load in contact with the adapter 2 ' , when connected by the mechanical connection 37 to the hub 2 and when this is connected to the crankshaft or directly with a crankshaft i f the adapter 2 ' is not present .

[0038] According to the invention, the hub 2 and / or the adapter 2 ' defines a surface processing 2b on the surface 2a configured to increase the friction between the hub 2 and the adapter 2 ' , preventing it from unscrewing .

[0039] In particular, the surface processing 2b is a type of processing of the laser texturing type .

[0040] Surface processing 2b, in particular by laser texturing, is defined by grooves and / or protuberances so as to provide a predefined roughness to increase friction between hub 2 and adapter 2 ' .

[0041] Advantageously, therefore , surface processing 2b defines a topology of grooves and / or protuberances arranged along topologies with a defined or free shape .

[0042] Preferably, surface processing 2b is optimised according to the material and si ze of the hub 2 / adapter 2 ' as well as the torques to be transmitted through the latter .

[0043] In detail , surface processing 2b is configured to provide a roughness between 20 and 50 microns as a measure of roughness Rz ( according to roughness measurement standards ) .

[0044] As it can be inferred from Figure 2 , the entire surface 2a can be occupied by surface processing 2b .

[0045] In Figure 3 , several di f ferent surface processing 2b may be performed on parts of the surface 2a . In detail , in the embodiment shown, such surface processing 2b is carried out around the openings adapted to accommodate elements forming part of the mechanical connection 37 , i . e . the elements providing the axial load connecting the hub 2 and / or adapter 2 ’ .

[0046] As it can still be inferred from the figures , the shape can be free , such as according to a sequence of radial grooves ( Figure 2 ) or latticework ( Figure 3 ) .

[0047] The operation of the embodiment of the hub provided with a fixation system and the pulley according to the abovedescribed invention is as follows .

[0048] Once the mechanical connection 37 connects the hub 2 to the rotating shaft or the adapter 2 ' connects this to the hub 2 , the surface processing 2b hub 2 and adapter 2 ' . In this way, the resistant torque which prevents the slipping is increased in both possible rotation directions of the rotating shaft and thus of the hub 2 .

[0049] From the foregoing, the advantages of a hub and pulley according to the invention are obvious .

[0050] Thanks to surface processing 2b, the friction between hub 2 and rotating shaft or hub 2 and adapter 2 ' connected thereto can be signi ficantly increased, making disconnection between these elements more di f ficult .

[0051] In particular, surface processing 2b by laser texturing allows the roughness on the surface 2a to be precisely controlled, enabling the rotation-resistant torque between hub 2 and the relative coupling to be better designed .

[0052] In further detail , this roughness can be controlled according to the si ze and material of the hub 2 and / or adapter 1 , as well as with respect to design torques , thus allowing versatility and additional safety with respect to the disconnection of said elements .

[0053] This ef fect is further enhanced by the possibility of providing di f ferent topologies of surface processing 2b . In addition, surface processing 2b can be provided only on the portion of surface 2a involved in the coupling, reducing production costs .

[0054] Finally, it is clear that modi fications and variations can be made to the hub and pulley according to the present invention which, however, do not depart from the scope of protection defined by the claims .

[0055] As discussed, the surface portion 2a and the element involved in surface processing may be di f ferent .

[0056] Similarly, di fferent topologies and laser texturing surface processing arrangements can be provided .

[0057] As always defined, the pulley described above is merely an example and can be of any type provided with a hub, a crown and an interposed filtering unit .

Claims

CLAIMS1.- Hub (2) or hub adapter (2' ) for a filtering pulley (1) , said hub (2) or hub adapter (2' ) defining an axial surface (2a) adapted to co-operate in contact under axial load with an element of said pulley (1) , at least a portion of said surface (2a) being provided with a surface processing (2b) configured to increase the friction of said surface (2a) under said axial load.2.- Hub or hub adapter according to claim 1, wherein said surface processing (2b) is a laser texturing process.3.- Hub or hub adapter according to claim 1 or 2, wherein said surface processing (2b) includes one or more grooves and / or protuberances.4.- Hub or hub adapter according to one of claims 1 to3, wherein said surface processing (2b) defines a roughness Rz between 20 and 50 micrometers.5.- Hub or hub adapter according to one of claims 1 to4, wherein said surface processing (2b) defines a roughness Rz which is a function of the size and / or material of said hub (2) or hub adapter (2' ) and the torque to be transmitted through it.6.- Hub or hub adapter according to one of claims 1 to5, wherein said surface processing (2b) defines a topology of defined shape or random shape.7 Hub or hub adapter according to one of claims 1 to 6, wherein said surface processing (2b) can be carried out on the entire surface (2a) .8.- Hub assembly (2) comprising a hub (2) according to one of the preceding claims and a rotating shaft, said hub (2) being connected under axial load to a rotating shaft.9.- Assembly comprising a hub (2) and hub adapter (2' ) according to one of the preceding claims and a rotating shaft, said hub (2) being connected under axial load to said hub adapter (2' ) , said hub adapter (2' ) being connected to said rotating shaft.10.- Filtering pulley (1) comprising a hub (2) or hub adapter (2' ) according to one of claims 1 to 7 and adapted to be fixed to a rotating shaft.11.- Filtering pulley according to claim 10, further comprising a crown (3) mounted rotationally free on the hub (2) , and a filtering assembly operatively interposed between said hub (2) and said crown (3) .

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