Filtering device for a transmission portion

Abstract

Filtering device (5) for a transmission portion (1) comprising a gear wheel toothing (3) and a hub (2) supporting the gear wheel toothing (3), the filtering device (5) comprising a hub portion (2') that can be connected to the hub / shaft (2) of the transmission (1) and a crown (6) mounted coaxially and rotationally free with respect to the hub portion (2'), the crown (6) being configured to carry the gear wheel toothing (3) of the transmission (1), the filtering device (5) comprising a filtering unit operatively interposed between the crown (6) and the hub portion (2').

Description

[0001] "FILTERING DEVICE FOR A TRANSMISSION PORTION"

[0002] Cross-Reference to Related Applications

[0003] This Patent Appl ication claims priority from Italian

[0004] Patent Application No . 102024000018232 filed on August 2 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0005] Technical Sector

[0006] The present invention relates to a filtering device , preferably a filtering device for a gear transmission .

[0007] The present invention is pre ferably, though not exclusively, applied to a transmission for a heavy vehicle power take-of f , such as an agricultural vehicle or a truck . This application will be referred to below by way o f example .

[0008] Background of the Invention

[0009] As is known, the crankshaft in internal combustion engines is subj ect to torsion vibrations due to the recurrent stresses caused by combustion in the cylinders .

[0010] These vibrations are particularly intense at start-up and low speeds , as well as when special design solutions are involved, such as dual-clutch transmissions or start-stop systems .

[0011] In particular, the crankshaft can be used to supply power to power take-of fs , also known as PTOs , in work vehicles , such as agricultural vehicles , trucks or earth- moving vehicles .

[0012] In this case , torsion vibrations result in rotational irregularities of the transmission elements , such as the gear wheels that compose it . These vibrations clearly reduce the fatigue li fe of these gear wheels and can result in overloads that cause sudden failures .

[0013] In addition, these vibrations generate annoying noi ses that are also a source of energy inef ficiency .

[0014] Again, the above-mentioned power take-of fs may be subj ect to transients or variable loads on the user ' s side . These transient / variable loads also impose oscillating loads on the transmission, which is , thus , further overloaded .

[0015] Elastic couplings are known that are designed to reduce these vibrations during the passage of torque along the transmission shafts . However, these systems are inef fective in reducing transmitting vibrations along the transmission .

[0016] In addition, given their position in the engine , thus lubricated by its oil , known grease systems are not particularly ef fective as they tend to contaminate the engine / transmission oil .

[0017] The aim of the present invention is to provide a transmission that simply and inexpensively solves the above- mentioned technical problem .

[0018] Summary of the Invention

[0019] The above aim is achieved with a filtering device and a transmission as claimed in the attached claims forming an integral part of this description .

[0020] Brief Description of the Drawings

[0021] A preferred 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 :

[0022] • Figure 1 is a perspective view of a filtering device coupled to a transmission element according to the invention;

[0023] • Figure 2 is an exploded perspective view along axis A of the filtering device in Figure 1 ;

[0024] • Figure 3 is a first , axial cross-section view along the rotation axis of the filtering device in Figure 1 ; and

[0025] • Figure 4 is a second, axial cros s- section view along the rotation axis of the filtering device in Figure 1 . Detailed Description of the Invention

[0026] The attached figures show a portion of a transmi ssion 1 essentially comprising a shaft / hub 2 extending along a rotation axis A and a first gear wheel 3 defining a first toothing and a second gear wheel (not shown) defining a second toothing and supported by hub / shaft 2 , for example by means of a spline 4 .

[0027] Although not shown, first and second gear wheels 3 clearly engage additional transmis sion 1 elements , by means of their respective toothings .

[0028] The second gear wheel is advantageously supported f ixed by shaft 2 , speci fically by means of above-mentioned spline 4 on one end of it , while first gear wheel 3 is supported rotationally free in relation to shaft 2 , for example by means of rolling bearings ( as shown) .

[0029] According to the invention, the toothing of first gear wheel 3 is operationally connected to shaft 2 using filtering device 5 configured to filter the torsion oscillations occurring between shaft 2 and gear wheel 3 .

[0030] Speci fically, filtering device 5 comprises an annular crown 6 supported rotationally freely externally to shaft 2 and configured to rigidly support a toothing of transmission portion 1 . Speci fically, annular crown 6 is connected to first gear wheel 3 .

[0031] Filtering device 5 is , therefore , placed in a lubricated environment , that is , where there is lubricating oil , for example an engine compartment or transmission compartment . First gear wheel 3 is an engine element that transmits torque to crown 6 .

[0032] First gear wheel 3 could be replaced by a similar element , such as a belt , rolling contact element or other motion transmission element .

[0033] Crown 6 essentially comprises a first element 7 and a second element 8 connected to define a space 9 . First element 7 advantageously comprises an annular wall 11 of axis A and a radial wall 12 , which is integral with annular wall 11 and preferably comprising one piece with it , extending radially towards shaft 2 .

[0034] Speci fically, radial wall 12 is configured to be connected to the gear wheel via a corresponding mechanical connection (not visible in the cross section in Figure 2 ) . For this purpose , holes are provided to accommodate fasteners such as screws or rivets .

[0035] Second element 8 comprises an annular wall 13 of axis A and a radial wall 14 , which is integral with annular wall 13 and preferably comprising one piece with it , extending radially towards shaft 2 .

[0036] In the embodiment described, second element 8 is planted in first element 7 to form above-mentioned space 9 . The latter is axially contained with respect to axis A by radial walls 11 and 13 and radially delimited with respect to axis A, on one side, by annular wall 12 of second element 8 and open towards shaft 2 .

[0037] At least one of first and second elements 7 , 8 comprise two diametrically opposite protuberances 14 , 15 extending axially into chamber 9 .

[0038] In the embodiment described, in particular, both first and second elements 7 , 8 comprise protuberances 14 , 15 extending from radial walls 11 , 13 ( see Figure 2 ) . These protuberances 14 , 15 advantageously face each other and, thus , divide space 9 into two , preferably equally si zed portions .

[0039] Protuberances 14 and 15 are preferably supported fixed by the respective walls or, alternatively, consist of a single piece with them .

[0040] Filtering device 1 also includes a filtering group operationally placed between crown 6 and shaft 2 .

[0041] In particular, the filtering group comprises at least one elastic group 20 (best seen in Figures 2 and 3 ) , for example two elastic groups 20 that are arched and arranged circumferentially free in the respective portions of space 9 delimited by protuberances 14 , 15 .

[0042] Each of elastic groups 20 comprises at least one spring, in the example described, a helical and arched spring 21 mounted between above-mentioned protuberances 14 , 15 .

[0043] Several springs can clearly be provided, in series or parallel with each other, with fixed or variable sti f fness , or housed in sliding blocks facilitating the sliding of the elastic groups in space 9 between protuberances 14 , 15 .

[0044] Descriptive examples can be found in the patents IT102015000009369 Al , IT102015000009371 Al or IT102017000021137 Al , the contents of which are incorporated by reference in this application and are applied where possible with regard to the filtering group placed between hub 2 ' and crown 6 .

[0045] Filtering device 1 additionally comprises an actuator 25 driven by shaft 2 configured to selectively cooperate in contact with the elastic groups to transmit torque between hub portion 2 ' and crown 6 .

[0046] Actuator 25 comprises two spokes 26 that are free to move circumferentially in space 9 and to cooperate in contact , circumferentially, with elastic groups 20 as described below .

[0047] Actuator 25 is advantageously supported by a hub portion 2 ' that can be attached to shaft 2 . In the embodiment shown, hub portion 2 ' consists of one piece with shaft 2 , thus forming a radial flange extending radially from shaft 2 on the opposite side of second gear wheel 4 .

[0048] Speci fically, actuator 25 is supported by hub portion 2 ' by means of a mechanical coupling 27 , for example using a riveted coupling .

[0049] Actuator 25 can be placed in contact with elastic groups 20 , in particular with suf ficient circumferential interference to preload elastic groups 20 within space 9 . Alternatively, it can be placed with an angular gap with respect to elastic groups 20 , that is , an angular clearance , before making contact with them .

[0050] Filtering device 1 may also include a damping system 40 configured to provide a pre-set amount of damping for the rotation between hub 2 and crown 6 . In the embodiment described, it extends between first gear wheel 3 and actuator element 25 .

[0051] In particular, damping system 40 comprises a sealing element 42 configured to be placed in contact with gear wheel 3 ( or, alternatively, actuator 25 ) and an elastic element 41 configured to impart an axial compression force along axis A, as in the example shown .

[0052] In particular, elastic element 41 may comprise a plate spring, advantageously of the coned-disc or Belleville spring type , supported integrally with actuator 25 or a diaphragm spring clamped onto it .

[0053] Thus , the spring defines an inner end and an outer end, with the outer end cooperating with sealing element 42 to provide it with the compression force along axis A.

[0054] The inner end is rigidly supported by actuator 25 and, in the example described, is advantageously fastened to hub portion 2 ' .

[0055] Filtering device 1 can also be fitted with a dynamic damper (not shown ) such as a seismic mass damper or inertia or viscous ring damper . This damper could be attached to hub portion 2 ' on the opposite side of first gear wheel 3 ' .

[0056] It should also be noted that first and second elements 7 , 8 are both provided with axial openings 51 , 52 along the rotation axis of the filtering device in Figure 1 that are configured to enable oil 1 to flow through space 9 .

[0057] Speci fically, openings 51 , 52 are formed on respective radial walls 11 , 13 . They are , advantageously, circular in shape and equal in number .

[0058] Even more advantageously, holes 51 on first element 7 have a larger diameter than holes 52 on second element 8 .

[0059] In addition, holes 51 and 52 of first and second elements 7 , 8 are parallel to axis A but not coaxial with each other .

[0060] Holes 51 on first element 7 are , advantageously, placed radially outside holes 52 on the second element to define a predetermined oil level within space 9 .

[0061] Advantageously, first gear wheel 4 also has holes 53 configured to allow oil to flow . These holes 53 are advantageously coaxial with respect to holes 51 of first element 51 and advantageously face it , that is , are continuous with it , as radial wall 11 is in contact with it .

[0062] In particular, holes 51 of first element 7 , holes 52 of second element 8 and ( i f included) holes 53 of first gear wheel 4 are circumferentially spaced along longitudinal axis A and, in particular, spaced equally apart . In the embodiment described, there are between four and six of them .

[0063] Filtering device 1 preferably comprises a seal 54 , for example an o-ring, radially arranged between radial wall 11 and the first gear wheel so as to prevent oil flowing between above-mentioned holes 53 and 51 from leaking out . Advantageously, one of either device 1 and first gear wheel 4 comprises a cover 55 configured to define a space 56 for forming an oil reserve , which can be directed to space 9 , via holes 51 in first element 7 .

[0064] In the embodiment described, cover 55 is annular and supported by first gear wheel 4 . It comprises a first , cylindrical portion 55 ' rigidly supported by first gear wheel 4 and a second, radial portion 55 ' extending radially inwards from one end of first portion 55 ' to define a space 56 .

[0065] First portion 55 ' is advantageously accommodated, under pressure , in a seat defined in gear wheel 4 . Space 56 is thus radially delimited by first portion 55 ' , externally, and open, internally . In addition, it is axially delimited on one side by gear wheel 4 , in the portion defining holes 53 , and delimited on the other side by second portion 55 ' .

[0066] The operation of the transmission and filtering device is described below .

[0067] In the first "driving mode" operation step constituting the normal operation of transmission 1 , first gear wheel 3 drives crown 5 . Imagining a condition wherein the play between elastic groups 20 and spokes 26 is recovered, the contact between them rotates hub portion 2 ' and, thus , shaft 2 and second gear wheel 4 . I f spokes 26 are placed with free play, this condition would be recovered first . During this operation, any torsion oscillations are recovered by elastic means 21 .

[0068] The above occurs , at the same time , in the "overrun" condition, that is , when the speed of hub portion 2 ' tends to exceed that of crown 6 .

[0069] Depending on the damping between hub portion 2 ' and crown 6 , as is known, there may be hysteresis with respect to the two operations described above .

[0070] Whether preloaded or spaced from the elastic groups , actuator 25 allows or does not allow angular play between hub portion 2 ' and crown 6 .

[0071] During the movement between hub portion 2 ' and crown 5 , damping system 40 is rotated around axis A. During this sliding, it provides a force along axis A to cover 11 generating damping for the rotation between hub portion 2 ' and crown 6 .

[0072] I f present , the damper further contributes to damping torsion oscillations between crown 6 and hub portion 2 ' .

[0073] In addition, during the movement around axis A, the centri fugal force tends to suck the oil present in the environment around filtering device 1 through holes 51 ( and 53 in this example ) , filling space 9 up to the predetermined level defined by second holes 52 . In addition, the cover on first gear wheel 4 enables the presence of a continuous oil reservoir in space 56 . The advantages of a transmission portion 1 according to the invention are therefore clear .

[0074] Thanks to the presence of the filtering device , torsion oscillations can be dampened in a transmission portion, particularly between a gear wheel and its hub / shaft .

[0075] This device is advantageously compact and easily adaptable to various si zes / positions in the transmission portion . In particular, this is owing to the fact that the actuator can be attached to any hub portion and crown 6 can be attached to any portion of the gear wheel , or vice versa .

[0076] In particular, by varying the type / si ze of the filtering elements and any play ( or preload) between the actuator and filtering elements , it is possible to simply design the type of torsion damping required for the torque involved .

[0077] It is finally clear that modifications and variations can be made to the filtering device without thereby departing from the scope of protection defined by the claims .

[0078] As mentioned, with reference to elastic group 20 , they could be produced without changing their function . For example , they could include springs of a di f ferent kind or several springs , in series or in parallel . Again, there could be four elastic groups as well as actuator spokes .

[0079] The dynamic damper, as mentioned, may not be included and the actuator could be supported di f ferently by hub portion 2 ' , which could be attached to the shaft and thus produced as a different element.

[0080] Again, the shape of the damping system 40 may vary according to the limits stated in the claims.

[0081] Similarly, the engine elements, such as gear wheel 3, could be replaced by other elements, such as a belt, or a different type of gear wheel.

[0082] Additionally, the number of holes 51, 52, 53, their diameter and position may vary.

[0083] Similarly, sealing element 54 or cover 55 may not be included or have a different configuration.

Claims

CLAIMS1.- Filtering device (5) for a transmission portion (1) comprising a gear wheel toothing (3) and a hub (2) supporting said gear wheel toothing (3) , said filtering device (5) comprising a hub portion (2' ) that can be connected to said hub / shaft (2) of said transmission (1) and a crown (6) mounted coaxially and rotationally free with respect to said hub portion (2' ) , said crown (6) being configured to carry said gear wheel toothing (3) of said transmission (1) , said filtering device (5) comprising a filtering unit operatively interposed between said crown (6) and said hub portion (2' ) , wherein said crown (6) is defined by at least one element (7, 8) , said at least one element (8) being fastened to said toothing of said gear wheel (3) .2.- Filtering device according to claim 1, wherein said filtering group comprises at least one elastic group (20) arranged circumferentially with respect to said hub portion (2' ) and said crown (6) and each interposed between a pair of first elements (26) integral with said hub portion (2' ) and between a pair of second elements (14, 15) integral with said crown ( ) .3.- Filtering device according to claim 2, wherein said first elements comprise at least two spokes (26) carried by an actuator (25) integral with said hub portion (2' ) .4.- Filtering device according to one of claims 2 or 3, wherein said elastic groups (20) comprise at least one arched spring (21) .5.- Filtering device according to one of claims 2 to 4, wherein said elastic groups (20) are placed in contact with preload between at least one of said first and second elements (26, 14, 15) or with predefined angular play between at least one of said first and second elements (26, 14, 15) .6.- Filtering device according to claim 2 to 5, wherein said second elements (14, 15) comprise protuberances extending into said space (9) from at least one element (7, 8) defining said crown (6) .7.- Device according to one of the preceding claims, wherein said element (7, 8) is fixed to said toothing of said gear wheel (3) by means of a reversible mechanical connection .8.- Device according to one of the preceding claims, further comprising a damping system (40) configured to provide an axial force generating a damping to the movement between said hub portion (2' ) and said crown (6) and comprising an elastic element (41) provided with a first end to said one between said hub portion (2' ) and said crown (6) and a second end cooperating with said other between said hub portion (2' ) and said crown (6) .9.- Device according to claim 8, wherein said elasticelement (41) is a cup or diaphragm spring.10.- Device according to one of claims 8 or 9, comprising a sealing element (42) cooperating with said elastic element (41) and sliding between said hub portion (2' ) and said crown (6) .11.- Device according to one of the preceding claims further comprising a dynamic damper rigidly connected to said hub portion (2' ) .12.- Assembly comprising a first gear wheel (3) , a hub / shaft (2) and a second gear wheel, one of said gear wheels (3) being carried rotatably free with respect to said hub / shaft (2) , said one of said gear wheels (3) being operatively connected to said hub / shaft (2) by means of a filtering device (5) according to one of the preceding claims .13.- Assembly according to claim 12, wherein said hub portion (2' ) is made of a single piece with said hub / shaft (2) .

14. - Transmission comprising an assembly according to claim 12 or 13.

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