WO2019142114A1

WO2019142114A1 - Filtering pulley

Info

Publication number: WO2019142114A1
Application number: PCT/IB2019/050344
Authority: WO
Inventors: Gianluca Cariccia; Andrea Guala; Ettore GAUDE; Daniele ESPOSTO; Markus Armbrust
Original assignee: Dayco Europe S.R.L.
Priority date: 2018-01-16
Filing date: 2019-01-16
Publication date: 2019-07-25
Also published as: DE112019000430T5; IT201800001112A1

Abstract

An indicator device (60) for a filtering pulley (1), the pulley (1) comprising a hub (2) adapted to be fixed to a rotating shaft, a crown (3) mounted in a coaxial and rotationally free manner on said hub (2) and configured to cooperate with a drive belt, elastic filtering means interposed between the hub (2) and the crown (3); the indicator device (60) comprising a fixing portion (61) integral to said hub (2) and at least an indication portion (62) carried by the fixing portion (61), the at least one indication portion (62) defining the value of the angular offset of the pulley (1) in respect to a fixed reference in respect thereto.

Description

"FILTERING PULLEY"

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 10201800001112 filed on 16/01/2018, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a filtering pulley, preferably a pulley for a crank shaft in an accessory drive of an internal combustion engine.

BACKGROUND ART

As is known, the drive shaft in internal combustion engines is subject to torsional vibrations due to the periodic stresses caused by combustion in the cylinders. Said vibrations are particularly intense at start-up and at low speeds, and in the presence of particular construction solutions such as, for example, the use of dual-clutch transmissions or start-stop systems .

The torsional vibrations translate into irregularities in rotation of the drive pulley of the accessory drive which are transmitted to the accessories by means of the drive belt, which is therefore subject to periodic tension variations.

In order to "filter" the torsional oscillations transmitted from the crank shaft to the belt, a filtering pulley is generally used as drive pulley, provided with a hub integral with the drive shaft, a crown cooperating with the belt and one or more elastic elements via which the drive torque is transmitted from the hub to the crown.

Pulleys defining a free rotation angle between hub and pulley in which no torque is transmitted are also commonly used. This free rotation angle is provided in order to improve the filtering thereof.

An example of a pulley of this type is described in WO 2016/151455 A1.

Once fixed to the drive shaft, said filtering pulley must be rotated to be mounted with a particular angular offset with respect to a position of an engine reference piston. Said position is defined by a reference point, normally indicated on the engine casing.

For mounting the pulleys of the other accessories, it is furthermore necessary to offset the filtering pulley differently according to the type of accessory. For example, the filtering pulley must be mounted with a particular timing with respect to the water pump pulley which differs, for example, from that of the alternator. The reference on the engine casing, usually a notch protruding from the latter, is used for this purpose.

To allow the above, the known filtering pulleys are provided with a sort of "goniometer" produced graphically/ by engraving on a surface of the pulley fixed with respect to the hub, and therefore with respect to the drive shaft. Usually said surface is the outer annular surface of the dynamic damper.

However, once mounted on the engine casing, the portion comprising the goniometer is normally partially concealed by the portion of pulley configured to cooperate with the drive belt or by the drive belt itself. It is therefore difficult for the operator who has to set the timing to identify the angle of the pulley with respect to the drive shaft .

Said indication of the angular offset of the pulley with respect to the drive shaft is an essential reference point in the case of pulleys of the type described above in which the free angle between hub and crown prevents a clear identification of the effective angular offset of the pulley. Again, said indication is a great help in the case of replacement of the pulley.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a filtering pulley that solves the above technical problem simply and inexpensively .

The above-mentioned object is achieved by an indicator device and a filtering pulley according to the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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, in which:

• figure 1 is an exploded perspective view of a pulley according to the invention;

• figure 2 is a diametral section of a pulley according to the invention;

• figure 3 is a perspective view of the pulley of figure 1 with parts removed for clarity.

BEST MODE FOR CARRYING OUT THE INVENTION

Figures 1 to 3 show a filtering pulley 1 comprising a hub 2 with axis A, adapted to be connected to a shaft (not shown) , for example a crank shaft of an internal combustion engine, and an annular crown 3 externally coaxial with the hub 2 and supported in a rotationally free manner on the hub 2 by support means 4, preferably sliding, such as, for example, roller (ball, needle) bearings or a bushing, for example made of plastic or bi-material (steel with anti-friction outer layer) .

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 one single piece with it, extending radially towards the hub 2, and a substantially cylindrical inner wall 8 with axis A.

The crown 3 carries, integral with it, a closing element 11 comprising an outer cylindrical wall 12 with axis A, a flat radial annular wall 13 and an inner cylindrical wall 14 with axis A, extending in a cantilever fashion from the wall 13 on the opposite side of the cylindrical wall 12. The closing element 11 is driven into the crown 3 so as to form an annular chamber 15 radially comprised between the wall 12 and the wall 8 and axially delimited by the wall 7 and by the wall 13. Lastly, the closing element 11 comprises two diametrically opposite projections 16, 17 extending axially inside the chamber 15 from the wall 13 and two openings (not illustrated) obtained in the wall 14 and positioned halfway along the angular distance between the projections 16, 17.

The wall 7 of the crown 3 forms projections (not illustrated) corresponding to and facing the projections 16,17 of the closing element 11.

The pulley 1 can further 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.

The pulley 1 can further comprise a friction damper 27 radially interposed between the wall 14 of the element 11 and the hub portion 22 of the disc 21 of the dynamic damper 19. The damper 27 substantially comprises a C-shaped bushing 28 cooperating slidingly with a cylindrical surface obtained on the hub portion 22, and an open metal ring 29 mounted by radial press-fitting on the bushing 28 and rotationally coupled thereto, for example by means of a pair of radial projections (not illustrated) which engage corresponding holes in the ring 29.

The pulley 1 further comprises elastic means for torque transmission between the hub 2 and the crown 3. Said means comprise a plurality, for example two, of arched elastic assemblies 40 arranged circumferentially free in the respective portions 15a, 15b of the chamber 15 delimited by the projections 16 and 17. The travel of the elastic assemblies 40 in the respective portions 15a, 15b is given by an angular clearance present between each of the elastic assemblies 40 arranged in contact with one of the projections 16, 17 and the other projection 17, 16.

Each of the elastic assemblies 40 comprises a pair of arched helical springs 41,42, positioned in sequence to each other and mounted between respective end sliding blocks 43 and an intermediate sliding block 44. The springs 41,42 have different rigidities, more precisely more rigid and less rigid as will be described better below. The sliding blocks 43 each comprise an arched portion 45 which surrounds internally an end portion of the respective spring 41,42, and a head 46 defining an axial support for said end portion. The sliding block 44 comprises an arched portion 47 which surrounds internally respective opposite end portions of the springs 41,42 and an intermediate radial wall 48 ranging between the two springs 41,42.

Lastly, the pulley 1 comprises an actuator 49 axially interposed between the hub 2 and the disc 21 of the dynamic damper 19 and integral with them. The actuator 49 has two spokes 50 free to move circumferentially in the chamber 15 and adapted to interact with the elastic assemblies 40. Assuming that the actuator 49 is arranged so that each of the spokes 50 is angularly equispaced with respect to the elastic assemblies 40, the angle between each of the spokes 50 and each of the elastic assemblies 40 will be equal to ² , where s represents the total angular clearance between the spokes 50 and the elastic assemblies 40.

According to the present invention, the pulley 1 further comprises an indicator device 60 configured to show, in a visible manner, the angular position of the pulley 1.

The indicator device 60 comprises a fixing portion 61 carried by an element of the pulley 1 integral with the hub 2 and an indication portion 62 carried by the fixing portion 61 configured to show the value of the angular position of the hub 2 in a visible manner above the crown 3.

Advantageously the fixing portion 60 can comprise a ring 70 fixed to an outer surface 23a of the seismic ring 23.

In order to allow integral coupling between ring 70 and surface 23a, the ring 70 can comprise a plurality of projections 71 configured to cooperate with respective seats

72 provided on the surface 23a.

Advantageously the indication portion 62 can comprise at least a tab 73 extending parallel to the axis A from a side edge of the ring 70 above the crown 3.

The tab 73 can be further raised from the ring 70 by means of a connection 75 configured to increase the distance of the tab

73 from the crown 3 so as to prevent an interference with a drive belt cooperating with the pulley 1.

Preferably the indication portion 62 comprises one single tab 73 configured to indicate the position of 0° of the hub 2; said indication can be printed on the upper surface of the tab 73 or be indicated by a notch on the centre line thereof.

The ring 70 further comprises a plurality of indication means, for example provided by means of notches 74 on the outer surface of the ring, angularly equispaced from one another from the position of 0° at a predefined angular interval, for example 20°.

The indicator device 60, in the case described the ring 70, is advantageously made of a plastic material, for example ABS or PVC . Furthermore, the device 60 is preferably made in one single piece.

Operation of the indicator device 60 and the pulley 1 comprising the latter is the following.

Once the pulley 1 has been fixed to the drive shaft, the user rotates the pulley until the position of the reference cylinder is correct, i.e. the indication of 0° coincides with the notch on the engine casing.

For the installation with offset of the drive accessories, it is sufficient to rotate the pulley until one of the notches 74 coincides with the reference notch on the engine casing.

The advantages of an indicator device 60 and a pulley 1 according to the invention are therefore evident.

The indicator device 60 facilitates display of the angular position of the pulley 1 in a simple inexpensive manner. The use of a ring 70 carried by the seismic ring 23, which is usually the element integral with the hub 2 with larger diameter, facilitates display of the angular position of the pulley 1 without increasing the overall dimensions of the pulley 1 or interfering with the drive belt.

The ring 70 can furthermore be produced to be applied to existing pulleys, for example modifying the diameter thereof so as to define a friction coupling with the outer surface of the seismic ring 23.

Furthermore, there can be more than one label 73 so as to clearly highlight any offset angles of particular importance.

Lastly it is clear that modifications or variations can be applied to the indicator device 60 and the pulley 1 described which do not depart from the protective scope defined by the claims .

For example, the ring 70 could be carried by an element different from the seismic ring 23 or the indicator device 60 may not be a ring but may comprise a fixing portion 61 of any shape and size.

Again, the indication portion 62 could be made differently or, as said, the tabs 73 could be more than one or absent.

Again, the indication means could be produced differently from the notches 74 described above, for example by means of projections or again colours/wording provided on the outer surface of the ring 70.

Lastly, fixing of the fixing portion 61 on the element integral with the hub 2 could be achieved differently from what is described, for example by friction or welding or by means of threaded connections.

Claims

1.- An indicator device (60) for a filtering pulley (1), said pulley (1) comprising a hub (2) adapted to be fixed to a rotating shaft, a crown (3) mounted in a coaxial and rotationally free manner on said hub (2) and configured to co operate with a drive belt, elastic filtering means interposed between said hub (2) and said crown (3), said indicator device

(60) being characterised in that it comprises a fixing portion

(61) integral to said hub (2) and at least an indication portion (62) carried by said fixing portion (61), said at least one indication portion (62) defining the value of the angular offset of said pulley (1) in respect to a fixed reference in respect thereto.

2. - The device according to claim 1, characterised in that said indication portion (62) defines the value of the angular offset above said crown (3) without interfering with said drive belt .

3. - The device according to claim 1 or 2, characterised in that said fixing portion (61) comprises a ring (70) .

4. - The device according to claim 1 or 2, characterised in that said at least one indication portion (62) comprises a tab (73) protruding from said fixing portion (61) parallel to the axis of said pulley (1) above said crown (3) .

5. - The device according to any one of the preceding claims, characterised in that one of said fixing portion (61) or an element integral to said hub (2) comprises a plurality of projections (71) configured to cooperate with respective seats (72) obtained in the other of said fixing portion (61) or said element integral to said hub (2) .

6. The device according to one of the preceding claims characterised in that said indicator device (60) is made in plastic material.

7. - The device according to one of the preceding claims, characterised in that said indicator device (60) is made in a single piece.

8. The filtering pulley (1) comprising a hub (2) adapted to be fixed to a rotating shaft, a crown (3) mounted in a coaxially and rotationally free manner on said hub (2) and configured to cooperate with a drive belt, an elastic filtering unit interposed between said hub (2) and said crown (3), said pulley (1) being characterised in that it comprises said indicator device (60) comprising a fixing portion (61) integral to said hub (2) and at least an indication portion (62) carried by said fixing portion (61), said at least one indication portion (62) defining the value of the angular offset of said pulley (1) with respect to a fixed reference in respect thereto.

9. - The pulley according to claim 8, characterised in that said indication portion (62) defines the value of the angular offset above said crown (3) without interfering with said drive belt .

10. - The pulley according to claim 8 or 9, characterised in that said fixing portion (61) comprises a ring (70) and in that said at least one indication portion (62) comprises a tab (73) protruding from said ring (70) parallel to the axis of said pulley (1) above said crown (3) .

11. - The pulley according to one of the claims from 8 to 10, characterised in that one of said fixing portion (61) or an element integral to said hub (2) comprises a plurality of projections (71) configured to cooperate with respective seats (72) obtained in the other of said fixing portion (61) or said element integral to said hub (2) .

12. - The device according to one of the claims from 8 to 11, characterised in that said indicator device (60) is made in plastic material and/or is made in a single piece.