Improved filtering pulley

Abstract

Filtering pulley (1) comprising a hub (2) suitable for being fixed to a shaft rotating around an axis (A), a crown (3) and a closing element (11) associated with the crown (3) and definining with it a space (15), the crown (3) and the closing element (11) being mounted coaxially and rotationally free on the hub (2), at least one elastic system (25) arranged circumferentially with respect to the hub (2) and to the crown (3) and interposed between a pair of first elements (26) integral with the hub (2) and between a pair of second elements (16) integral with at least one of the crown (3) and the closing element (11), wherein the closing element (11) is supported by the hub (2), the crown (3) being rigidly carried by the closing element (11).

Description

[0001] IMPROVED FILTERING PULLEY

[0002] Cross-Reference to Related Applications This Patent Application claims priority from Italian Patent Application No . 102024000029751 filed on December 23 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0003] Technical Field

[0004] The present invention relates to a filtering pulley, preferably a pulley for a crankshaft in an accessory drive of an internal combustion engine .

[0005] Background Art

[0006] As is known, the drive shaft in internal combustion engines is subj ect to torsional vibrations due to periodic stresses caused by the combustion in the cylinders . These vibrations are particularly intense at start-up and at low speeds , as well as in the presence of particular construction solutions , such as the use of double clutch gearboxes or start-stop systems .

[0007] Torsional vibrations translate into irregularities in rotation of the drive pulley of the accessory drive that are transmitted to the accessories by means of the drive belt , which is thus subj ect to periodic variations in tension .

[0008] With the aim of "filtering" the torsional oscillations transmitted from the crankshaft to the belt, a filtering pulley, provided with a hub integral with the drive shaft, a crown cooperating with the belt and one or more elastic elements through which the torque is transmitted from the hub to the crown, is generally used as drive pulley .

[0009] These filtering pulleys comprise a crown defining a portion suitable for cooperating with a belt . Normally, this portionis supported by the hub through support means such as bearings or bushings , as illustrated in WO2024 / 018324 Al . However, this configuration is particularly costly in terms of manufacture .

[0010] Moreover, this configuration is very restrictive in terms of design .

[0011] Therefore, there is the need to maintain the same filtering features, while reducing manufacturing costs and increasing design freedom.

[0012] The obj ect of the present invention is to provide a filtering pulley that solves the aforesaid technical problem in a simple and inexpensive way .

[0013] Summary of the Invention

[0014] The aforesaid obj ect is achieved by a filtering pulley according to what is claimed in the appended claims .

[0015] Brief Description of the Drawings

[0016] For a better understanding of the present invention, a preferred embodiment is described below by way of non-limiting example and with reference to the accompanying drawings, wherein :

[0017] • Fig . 1 is a perspective view of a filtering pulley according to the invention;

[0018] • Fig . 2 is an axial sectional view along the axis of rotation of the pulley of Fig . 1 ; and

[0019] • Fig . 3 is an exploded perspective view along its rotation axis of a filtering pulley according to the invention .

[0020] Detailed Description of the Invention

[0021] In the accompanying figures, a filtering pulley 1 is represented, the pulley comprising a hub 2 with axis A, suitable for being connected to a shaft (not represented) , for example a crankshaft of an internal combustion engine, and anannnular crown 3 externally coaxial to the hub 2 .

[0022] The crown 3 comprises a first annular portion 5 provided with a profile 6 suitable for cooperating with a poly-V belt (not represented) .

[0023] The crown 3 further comprises a first radial wall 7 , integral with the annular portion 5 and preferably in a single piece therewith, extending radially towards the hub 2 , a second annular wall 8 extending axially from the first radial wall 7 on the opposite side of the first annular portion 5 and advantageously cylindrical .

[0024] The crown 3 further comprises a second radial wall 9 extending radially on the opposite side of the second annular wall 8 with respect to the first radial wall 7 .

[0025] The crown 3 carries, integral therewith, a closing element 11 comprising a first annular wall 12 , advantageously cylindrical , with axis A, a radial wall 13 extending radially from one end of the first annular wall 12 and a second annular wall 14 extending axially from the radial wall 13 from the end opposite to the first annular wall 12 .

[0026] In the embodiment described, the closing element 11 is driven into the crown 3 so as to form an annular chamber 15 axially comprised between the second radial wall 9 of the crown 3 and the radial wall 13 of the closing element 11 and radially comprised between the second annular wall 8 of the crown 3 and the second annular wall 14 of the closing element 11 .

[0027] Advantageously, the closing element 11 is carried by the hub 2 by the aforesaid support means 4 , in particular is directly supported thereby and, in further detail, both axially and radially with respect to the axis A.In detail, the first support means 4 comprise radial support means 4 ' and axial support means 4 ' ' respectively radially and axially interposed between the closing element 11 and the hub 2 .

[0028] Preferably, these radial and axial support means 4 ' , 4 ' ' each comprise a bushing . Advantageously, the hub 2 is shaped so as to define a shoulder suitable for allowing axial support between closing element 11 and hub 2 through the axial support means 4 ' ' .

[0029] Finally, at least one of the closing element 11 and the crown 3 comprises at least one pair of diametrically opposite proj ections 16 extending axially inside the chamber 15. These proj ections 16 divide the chamber 15 into respective portions preferably of the same circumferential extension along the axis A.

[0030] In the embodiment described, both the closing element 11 and the crown 3 each comprise two proj ections 16 respectively extending from the radial wall 13 and from the second radial wall 9, towards each other, thus dividing the chamber 15 in two .

[0031] Advantageously, the proj ections 16 are carried fixed by the respective elements, advantageously produced in a single piece .

[0032] As illustrated, the pulley 1 further comprises at least one elastic system 20, arranged circumferentially free in the portions delimited by the proj ections 16 in the chamber 15, hence in the case described two elastic systems 20.

[0033] Each of the elastic systems 20 comprises at least one spring 21 configured to act through compression, in the case described a helical and arched spring 21 mounted between theaforesaid proj ections 16.

[0034] Advantageously, the spring 21 can be housed in portion of chamber 15 with preload or with a predetermined angular clearance .

[0035] The pulley 1 further comprises an actuator 25 carried integrally by the hub 2 . The actuator 25 has two spokes 26 free to move circumferentially in the chamber 15 and suitable for interacting with the elastic systems 20 in contact, as described below .

[0036] Advantageously, the actuator 25 is carried by the hub 2 , for example via a threaded coupling or a pin, as represented and not described for brevity .

[0037] The actuator 25 can be placed in contact with the elastic systems 20, possibly with a circumferential interference value so as to preload these elastic assemblies 20 inside the portion of the chamber 15. Alternatively, it can be placed with an angular interval with respect to the elastic assemblies 20, i . e . , with an angular clearance before coming into contact therewith .

[0038] Advantageously, the actuator 25 comprises a body 27 connected to the hub 2 and carrying the spokes 26, for example in a single piece therewith, having an S-shaped section, i . e . , defining a fixing portion 27 ' and a connecting portion 27 ' ' advantageously parallel to each other and extending radially spaced from each other along the axis A and a j oint portion 27 ' ' ' , advantageously curved, j oining these fixing 27 ' and connecting 27 ' ' portions .

[0039] In detail, the j oint portion 27 ' ' ' passes inside the chamber 15 through an annular opening 28 produced between the second radial wall 9 of the crown 3 and the second axial wall 14 ofthe closing element 11 .

[0040] The pulley 1 can also be provided with a dynamic damper 19 comprising a disk 31 , facing the crown 3 and having a hub portion 32 integral with the hub 2 , and a seismic ring 33 constrained to a perimeter flange 31 ' of the disk 31 by a ring 34 in deformable, in particular elastomeric, material .

[0041] In detail , the flange 31 ' , the seismic ring 33 and the ring 34 are housed in a space delimited radially by the first and by the second axial wall 5, 8 of the crown 3 and axially by the first radial wall 7 thereof .

[0042] For this purpose, the disk 31 is shaped so as to have a concave shape, containing part of the crown 3 inside the concavity .

[0043] Furthermore, the disk 31 can define one or more openings 31 ' ' suitable for allowing ventilation between crown 3 and dynamic damper 29. In the embodiment described, these openings 31 ' ' are passing axially through the disk 31 and circumferentially spaced from one another, advantageously being of the same shape as, and equally spaced angularly from, one another .

[0044] The pulley 1 can also comprise a dust cover system 35 configured to isolate the space 15 from the external environment and, at the same time, to generate an axial force, i . e . , along the axis A, suitable for generating a damping between hub 2 and crown 3 .

[0045] In particular, the dust cover system 35 comprises a sealing element 36, in the embodiment described configured to be placed in contact with the second radial wall 9 of the crown 3 and, optionally, an elastic element 37 configured to impart an axial compression force along the axis A as in the case illustrated .In particular, the elastic element 37 can comprise a leaf spring, advantageously of coned-disc spring or Belleville washer type, carried integral by the actuator 25, or a diaphragm spring clamped thereon .

[0046] Therefore, the spring defines an inner end and an outer end, where the outer end is the one cooperating with the sealing element 36 to supply it with the compression force along the axis A.

[0047] The inner end is rigidly carried by the actuator 25 and in the case described, is advantageously clamped by friction between the actuator 25 and the dynamic damper 29.

[0048] Advantageously, the sealing element 36 has an L-shape cross section and comprises a radial portion and an axial portion . In particular, the axial portion is in contact, radially, with an inner annular edge of the second radial portion 9, while the radial portion is placed axially in contact with the end portion thereof and cooperates in contact with the elastic element 37 .

[0049] Therefore, advantageously, the elastic element 37 and the sealing element 36 are produced as separate elements . Preferably, the sealing element 36 is made in polymeric or plastic material .

[0050] Operation of the pulley 1 is described below.

[0051] In a first operating step, called "driving mode" and forming the normal operation of the pulley 1 , 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 26 of the actuator 25 transmit the torque to the proj ections 16 with the interposition of the respective elastic systems 20.The above occurs, symmetrically, in "overrunning" condition, i . e . , when the speed of the crown 3 tends to exceed the speed of the hub 2 .

[0052] According to the dampings present between the hub 2 and the crown 3, as known per se, a hysteresis may be present with respect to the two operations described above .

[0053] The actuator 25, if in preloaded contact or spaced from the elastic assemblies , allows or prevents angular clearance between hub 2 and crown 3 .

[0054] During the movement between hub 2 and crown 3, the dust cover system 35 is driven in its rotation around the axis A. During this movement, it performs the function of preventing dirt from reaching the space 15 and provides a force along the axis A to the crown 3 , generating a damping of the rotation between hub 2 and crown 3 .

[0055] Being advantageously present, the torsional damper 29 further damps the torsional oscillations between hub 2 and crown 3. Thanks to the openings 31 ' ' an air flow suitable for cooling the pulley 1 is permitted .

[0056] The advantages of a pulley 1 according to the invention are thus evident .

[0057] Thanks to inversion between crown and closing element, with respect to known systems , it is possible to reduce radial and axial dimensions of the pulley while maintaining the same filtering properties .

[0058] Consequently, also the weights and, hence, the related costs are reduced. Moreover there is greater design freedom, as it is possible to arrange the actuator on different sides of thehub or to use a single hub, depending on the circumstances .

[0059] At manufacturing level , manufacture of the pulley 1 is particularly simplified .

[0060] Finally, it is clear that modifications or variations can be made to the pulley described without departing from the scope of protection defined by the claims .

[0061] Firstly, the pulley could be used not only on the crankshaft of an internal combustion engine, but for one of the accessories thereof .

[0062] With reference to the elastic systems 25, they could be produced without however modifying their function . For example, they could comprise springs of different type or several springs, in series or in parallel . Further, the elastic assemblies could be four, as could the spokes of the actuator .

[0063] The dynamic damper could be absent and the actuator could be carried differently by the hub 2 . Further, the hub could be produced in two different pieces connected to each other .

[0064] Moreover, the support means 4 could comprise a rolling bearing or be produced as L-shaped bushing in a single piece .

Claims

CLAIMS1 . - Fi ltering pulley ( 1 ) compri sing a hub ( 2 ) suitable for being fixed to a shaft rotating around an axis (A) , a crown ( 3 ) and a clos ing element ( 11 ) associated with said crown ( 3 ) and de fining with it a space ( 15 ) , said crown ( 3 ) and said closing element ( 11 ) being mounted coaxial ly and rotational ly free on said hub ( 2 ) , at least one elastic system ( 25 ) arranged circumferential ly with respect to said hub ( 2 ) and said crown ( 3 ) and interposed between a pair o f first elements ( 26 ) integral with said hub ( 2 ) and between a pair o f second elements ( 1 6 ) integral with at least one o f said crown ( 3 ) and said clos ing element ( 11 ) ,wherein said closing element ( 11 ) is supported by said hub ( 2 ) , said crown ( 3 ) being rigidly carried by said closing element ( 11 ) through a revers ible mechanical coupling .2 . - Pul ley according to claim 1 , wherein said mechanical coupl ing compri ses a shape coupling .3 . Pulley according to claim 1 or 2 , compris ing support means ( 4 ) interposed between said closing element ( 11 ) and said hub ( 2 ) .4 . - Pulley according to claim 3 , wherein said support means ( 4 ) radial ly and axial ly support said closing element ( 11 ) with respect to said hub ( 2 ) .5 . - Pulley according to claim 3 or 4 , wherein said support means ( 4 ) compri se a first and a second bushing ( 4 ' , 4 ' ' ) respectively radial ly and axial ly interposed between said closing element ( 11 ) and said hub ( 2 ) .6 . - Pul ley according to one o f the preceding cl aims , further compris ing a dust cover system ( 35 ) carried integral ly by said hub ( 2 ) and conf igured to s lide , in a sealed manner, withrespect to said crown ( 3 ) , said dust cover system ( 35 ) being configured to isolate said space ( 15 ) from the external environment .7 Pul ley according to claim 6 , wherein said dust cover system ( 35 ) compri ses a sealing element ( 36 ) conf igured to s lide on said crown ( 3 ) and an elastic element ( 37 ) conf igured to impart an axial force between said hub ( 2 ) and said crown ( 3 ) on said sealing element ( 36 ) .8 . - Pul ley according to any o f the preceding cl aims , wherein said first elements compri se at least two spokes ( 2 6 ) carried by an actuator ( 25 ) integral with the hub ( 2 ) .9 . - Pul ley according to claim 8 , wherein said actuator ( 25 ) is carried by said hub ( 2 ) via a plural ity o f threaded coupling means .10 . - Pulley according to claim 9 , wherein said actuator ( 25 ) comprises a body ( 27 ) f ixed to said hub ( 2 ) , said spokes ( 26 ) extending from said body ( 27 ) and a j oint portion ( 27, , f) connecting said spokes ( 26 ) to said body ( 27 ) , said j oint portion ( 27 ' ' ' ) pas sing through an annular opening ( 28 ) def ined between said clos ing element ( 11 ) and said crown ( 3 ) .11 . - Pulley according to any of the preceding claims , wherein said second elements ( 16 ) are proj ections integral with at least one o f said closing element ( 11 ) and said crown ( 3 ) .12 . - Pul ley according to claim 9 , wherein said at least one elastic system ( 20 ) is s lidabl e circumferentially inside a seat ( 15 ) formed between said f irst elements ( 26 ) and / or said second elements ( 16 ) .13 . - Pulley according to one of the preceding claims , further compris ing a dynamic damper ( 19 ) fixed to said hub ( 2 ) on theoppos ite s ide of said closing element ( 11 ) with respect to said crown ( 3 ) .14 . - Pulley according to claim 13 , wherein said dynamic damper ( 19 ) comprises a dis k ( 31 ) , a seismic ring ( 33 ) and a ring ( 34 ) in de formable material connecting said seismic ring ( 33 ) to said di sk ( 31 ) , said dis k ( 31 ) de f ining a plurality of openings ( 31 ' ' ) pas sing through said di sk ( 31 ) .15 . - Pul ley according to claim 13 or 14 , wherein said crown ( 3 ) del imits an annular space , said seismic ring ( 33 ) and said ring ( 34 ) being housed in said annular space .

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