IT202000009139A1 - SEALING DEVICE INCLUDING A FLEXIBLE LIP WITH DYNAMIC COMPENSATION OF INTERFERENCE VARIATIONS - Google Patents

Description

Description accompanying a patent application for industrial invention entitled: SEALING DEVICE INCLUDING A FLEXIBLE LIP WITH DYNAMIC COMPENSATION OF INTERFERENCE VARIATIONS

DESCRIPTION

Technical Sector of the Invention

The present invention? relating to a sealing device having a flexible annular lip capable of dynamic compensation of interference variations, particularly suitable for being interposed between two members in relative rotation subject to rotational misalignments.

Technique Note

How ? known, the space between two mechanical parts in relative rotation, for example the inner and outer rings of a rolling bearing or a rotating shaft and its rotation seat, must be protected both from infiltration of external contaminants and from the leakage of any lubricating oil or grease present in this space. For this purpose, sealing devices are used comprising a substantially rigid annular shield or support, also called armature, which is angularly fixed integral with the mechanical member in stationary use and an annular sealing element carried integrally by the annular support, for example glued in vulcanization step, and provided with at least one annular sealing lip which protrudes radially from the annular support and which? configured to cooperate with interference and in a sliding way with the rotating mechanical member in use.

Such a solution? generally satisfactory, except in the case in which the sealing lip must work with relatively high interference and / or when the two mechanical parts in relative rotation, which are normally coaxial, are subject to misalignments during rotation.

In these particular cases, in fact, on the one hand the interference with which the sliding sealing lip cooperates with the rotating shaft can? vary over a wide interval, with consequent loss, at least partial, of the sealing action and / or premature wear of the sliding lip, and on the other hand, when they occur momentarily (due to the misalignment) or permanently (as required by the ? application) high interference between the sealing lip and the rotating member which leads to an undesired flattening / crushing of the sealing lip against the radially external surface of the rotating member.

Summary of the Invention

Purpose of the present invention? that of providing a sealing device which is free from the drawbacks of the state of the art and which is at the same time reliable and economical, in particular which can adapt to relatively strong interference and / or interference excursions between the sealing lip and the rotating member.

According to the invention, therefore, a sealing device is provided which can be inserted between a first and a second mechanical member in relative rotation, for example, but not exclusively, between a rotating shaft and a relative seat, having the characteristics set out in the appended claims.

Brief Description of the Drawings

The invention will come now described with reference to the attached drawings, which illustrate two non-limiting examples of implementation, in which:

Figure 1 schematically illustrates a partial radial sectional view of a first embodiment of the sealing device of the invention;

Figure 2 schematically illustrates a partial radial section view of a variant of the first embodiment of the sealing device of Figure 1;

Figure 3 schematically illustrates on an enlarged scale a partial radial sectional view of a second embodiment of the sealing device of the invention;

Figure 4 schematically illustrates on an enlarged scale and in radial section of a detail of a main sealing lip of the sealing device of the invention, where some characteristic configuration measures of the sealing lip are reported; And

Figure 5 schematically illustrates and in a radial view the operation of the sealing lip configuration of the sealing device of the invention.

Detailed Description

With reference to Figure 1, in it? indicated as a whole with 1 a sealing device which can be inserted between a first mechanical member 2 and a second mechanical member 3 relatively rotatable, known and illustrated only schematically and in broken lines for simplicity, for example consisting of a machine shaft 3, in use rotating, and a corresponding seat 2, in stationary use, for example formed in a support or other machine element such as an engine base.

The sealing device 1 comprises a substantially rigid annular support 4, configured to be fixed integral with the first mechanical member 2, in stationary use, and an annular sealing element 5 made of an elastomeric material and carried integrally by the annular support 4, for example glued in the vulcanization phase against a face 6 of the annular support 4.

The ring support 4? generally made of a metal material coined or printed at the press and? provided with a sleeve portion 7, radially external and with axial development, for keying to the stationary member 2. The sleeve portion 7? preferably completely covered, on the side of the face 6, by the elastomeric sealing element 5, so that the keying on the mechanical member 2 is in use carried out in a fluid-tight and forcing manner.

The annular sealing element 5? integrally provided with at least one first annular sealing lip 8 which extends radially from the annular support 4, starting from a radially internal perimeter edge 9 of a flange portion 10 of the annular support 4.

The flange portion 10 extends radially in cantilever fashion from one end. 11 of the sleeve portion 7, radially on the inside of the latter.

The annular sealing lip 8? configured to cooperate in contact and with interference with the second mechanical member 3, in rotating use. The latter can be subject in use to oscillations or other movements that make the design interference between the member 3 and the lip 8 vary significantly. In other cases, the sealing device 1 can? be called to be inserted between mechanical members 2 and 3 such that the design interference required between member 3 and lip 8 can? be significantly different, depending on the application required.

To meet these requirements, the first annular sealing lip 8 comprises, starting from the radial edge 9 of the annular support 4, a root portion 12, an intermediate portion 13 and a head portion 14, arranged in sequence.

Here and below, with the terms? Upstream? and? downstream? we will refer? to the radial direction along which the portions 12, 13 and 14 are arranged in sequence, therefore the intermediate portion 13 is arranged downstream of the root portion 12 and upstream of the head portion 14.

With reference now also to Figure 4, where the annular lip 8? schematically illustrated on an enlarged scale, the root portion 12 and the intermediate portion 13 have an opposite U-shape and are elastically bendable around a first fulcrum F2 and a second fulcrum F1 defined by respective centers of curvature of the U-shaped portions 12 and 13, so that the coupling between the latter, formed integrally with each other, forms, according to one aspect of the invention, a bellows 15 which can be folded in a radial direction.

The head portion 14 extends radially overhanging from the intermediate portion 13, from the opposite band to the root portion 12 and has a snake-head conformation in the radial section.

With reference also to Figure 5, the head portion 14, in fact, is? axially thickened in the middle with respect to the intermediate portion 13 and is connected to the intermediate portion 13 by means of a first curved surface 16 and a second curved surface 18, having opposite curvature.

The curved surfaces 16 and 18 are configured to define in a radial and outward direction of the first sealing lip 8, respectively, a first and a second concavity. annular shaped like a channel, indicated respectively with 19 and 20.

The first curved surface 16? turned towards the second fulcrum F1 and the head portion 14 tapers towards one end thereof? free 21 facing the opposite side to the intermediate portion 13.

From opposite band at the extremity? free 21, the head portion 14? delimited by an annular projection 22 which determines the axial thickening already? indicated of the head portion 14 and which has a convex shape.

The projection 22? delimited towards the outside of the lip 8 by a flat annular surface 23, facing the extremity? free 21, oriented obliquely with respect to an axis of symmetry A (figure 1) of the sealing lip 8 (normally coinciding with the axis of rotation of the mechanical member 3) and by a curved surface 24 close to, and connected with, the surface curve 16 and having a curvature opposite to that of the curved surface 16 and a radius smaller than that of the curved surface 16 and greater than that of the curved surface 18.

In this way, the head portion 14 presents, as already? indicated, a snake-headed shape similar to the side elevation profile of a cobra's head.

The first and second curved surfaces 16, 18 have, respectively, a first radius of curvature R3 and a second radius of curvature R5 (Figures 4 and 5) which are predetermined.

According to an aspect of the invention, the first radius of curvature R3 must be greater than the second radius of curvature R5. Furthermore, the ratio between the first and the second radius of curvature, that is? the R3 / R5 ratio? preferably made with a value between 3.2 and 5.

Thanks to the geometry described, the head portion 14 is connected to the intermediate portion 13 through a narrow annular section 25 having a transversal thickness SP3 smaller than both that of the head portion 14 and a transversal thickness SP5 of the root portion 12 (Figure 5 ) measured downstream of the first fulcrum F2 and immediately upstream of the intermediate portion 13 and of the respective second fulcrum F1.

The restricted section 25? bounded between the curved surfaces 16,18 and? configured to function as a plastic hinge constituting a third rotation fulcrum for the head portion 14 adapted to allow its rotation towards a loop 26 defined by the U shape of the intermediate portion 13.

The head portion 14 presents its extremity? free 21 delimited by a band opposite the intermediate portion 13 by a first annular flat surface 27 and by a second annular flat surface 28 (figure 4), which converge towards each other from a band opposite the intermediate portion 13 to define a first annular sealing edge 29 of the annular sealing lip 8. The surface 27 merges, forming an edge 30 (Figure 5) in the projection 22, while the surface 28 joins with the curved surface 18.

The U-shaped shape of the root portion 12 also defines a loop 31 (Figure 4) facing the same side as the second flat annular surface 28, while the U-shaped shape of the intermediate portion 13 defines, as already? indicated, a loop 26 facing away from the second flat annular surface 28.

According to an aspect of the invention (Figure 4), the first flat annular surface 27 forms in radial section and with a parallel p to the axis of symmetry A of the annular lip 8 a first angle? between 30? and 50?, while the second flat annular surface 28 forms in radial section with the parallel p to the axis of symmetry A of the annular lip 8 a second angle? between 45? and 65 ?. The values of the angles? And ? must be chosen within the aforementioned dimensional ranges so that the second angle? is always greater than the first angle?

One extremity? 32 (Figures 4 and 5) of the intermediate portion 13 immediately adjacent to the head portion 14? provided on the opposite side to the first and second fulcrum F2 and F1 with an annular projection defining a second annular sealing edge 33 of the first annular lip 8.

The sealing edge 33? facing the same side as the first annular sealing edge 29 of the sealing lip 8.

According to one aspect of the invention, while the first sealing edge 29? configured to always cooperate in contact with the second mechanical member 3, the projection defining the sealing edge 33 and the root portions 12 and intermediate 13 of the annular sealing lip 8 are configured so that the annular sealing edge 33 enters cooperation with the second mechanical organ 3 only after a radial folding of entities? of the bellows 15 formed by the root portions 12 and intermediate 13 and in such a way as to block, or delay, the flattening of the first annular sealing edge 29 as a result of a possible anomalous increase in interference between the first annular lip 8 and the second mechanical organ 3.

According to a further aspect of the invention, in order to achieve this effect with maximum efficiency and reliability, the ratio (Figure 4) between a first radial distance L1 between the second fulcrum F1 and a first sealing edge 29 of the annular lip 8 and a second radial distance L2 between the first fulcrum F2 and the second fulcrum F1 must be between 1.05 and 3.3.

For the same purpose, the ratio (Figure 4) between a first axial distance H1 between the first sealing edge 29 and the second fulcrum F1 and a second axial distance H2 between the first fulcrum F2 and an extrados surface 34 of the shaped intermediate portion 13 U-shaped and facing from the opposite band to the second fulcrum F1? between 0.7 and 1.50.

With reference now to figures 1 and 2, in figure 2? a possible variant 1b of the embodiment of the sealing device 1 of the invention of figure 1 is illustrated. described are indicated for simplicity? with the same reference numbers, also why? the two variants 1 and 1b differ only in the shape and dimensions of the support 4, being designed to operate between pairs of mechanical members 2,3 of significantly different diameter (the variant 1b being strung to mechanical members 2,3 having a larger diameter).

Both variants 1 and 1b include, in addition to all the details already? described, also an annular shield 35 driven into the radially outer sleeve portion 7 of the annular support 4 and which? opposite the first sealing lip 8.

The ring screen 35? provided with a sleeve portion 36 planted inside the sleeve portion 7 and with a flange portion 37 which extends radially and cantilevered from the sleeve portion 36 and towards the first sealing lip 8.

The flange portion 37 ends with a radially internal annular edge 38 folded obliquely from the band opposite the annular support 4 and arranged in a radial position substantially corresponding to that of the second fulcrum F1.

Finally, the root portion 12 of both variants 1 and 1b? provided with an annular camber or enlargement 39 obtained on a face 40 of the flange portion 10 opposite the face 6 and configured to cooperate abutment with the flange portion 37 of the screen 35 to act as a limit switch for introducing the screen 35 into the portion sleeve 7 of support 4, which? cup-shaped.

Referring now to Figure 3, in it? schematically illustrated a second embodiment 100 of the sealing device according to the invention. The details similar or the same as those already? described are indicated for simplicity? with the same numbers.

The sealing device 100 comprises a support 4 provided with an elastomeric sealing element 5 and supporting an annular sealing lip 8, having the same conformation already? described for the sealing lip 8 of variants 1 and 1b.

Similarly, the sealing device 100 also comprises an annular shield 41 arranged facing the annular support 4. The shield 41, however,? configured to be keyed integral with the second mechanical member 3 and therefore to rotate relative to the annular support 4 and to the first annular sealing lip 8.

A radially outer edge 42 of the annular shield 41? turned axially from the opposite band to the annular support 4 and? operatively associated with the radially outer sleeve portion 7 of the annular screen 41 to generate in use a centrifugation effect towards any external contaminants.

Furthermore, the annular sealing element 5? obtained only in correspondence with the root portion 12 of the annular lip 8 on face 6, while? obtained for the most part on the opposite face 40 of the flange portion 10 of the support 4.

The sealing element 5? moreover provided in correspondence with an intermediate portion 43 of the annular support 4 with at least a pair of second annular sealing lips 44 which axially slidingly cooperate with a corresponding intermediate portion 45 of the annular shield 41.

The intermediate portions 45 and 43 of the annular screen 41 and of the annular support 4 are substantially parallel and facing each other and are arranged obliquely with respect to the axis of symmetry A of the annular sealing lip 8.

They are in fact defined by sections of conical surface having conicity? facing from the opposite band to the first annular sealing lip 8. Here and below, for? conicity ?? we must understand the direction and towards which the ideal vertex of the conical surface to which we refer is located, that is the point around which the generating line of the conical surface to which we refer ideally rotates.

Thanks to what has been described, the following advantages are obtained:

? bulging or flattening of the sealing edge 29 is avoided; ? the contact area in the design interference intervals always remains in correspondence with the corner 29;

? the range of interference within which it can? acting with equal effectiveness the same sealing device 1, 1b, 100 is considerably extended;

? do you get greater flexibility? and lower deformation values of the main sealing lip 8; And

? greater contact forces are obtained between member 3 and edge 29 in all conditions, with a consequent improvement in sealing against water and mud.

The radius R5 creates an area that is opposed in a more? effective at deformations, delaying the flattening of the lip 8. In addition, the flexion area is stiffened.

The second sealing contact created by the annular edge 33 stabilizes the axial position of the sealing lip 8, reducing the displacements in the "Y" direction, engaging the lip 8 to rotate around the fulcrum F1.

Also, the radius R5, the angle? and the second contact 33 allow the lip 8 to work at the edge for the entire interference interval foreseen in the project.

The radius R5, the angle?, The radius R3 together with the lengths L1, L2 and the? Heights? H1, H2 give the lip 8 the capacity? to have more? high design interference ranges.

The two fulcrums of rotation F1 and F2 give the lip 8 a greater capacity? of bending, reducing internal deformations. The relationship between the lengths L1 and L2, establish the right compromise of rigidity? between the two fulcrums, increasing the capacity? of the lip 8 to close on itself, in a radial direction, without excessively altering the axial positioning? Y? of the same.

The thickness variation, indicated by the SP3 dimension, serves to reduce the contact forces in the conditions of maximum interference, generating a third rotation fulcrum which has an effect only in the conditions of maximum interference.

The presence and shape of the projection 22 gives the lip 8 in the contact area a greater volume of rubber than in the flexible section. This ? useful to increase the contact forces and increase the capacity? sealing against contaminants such as water and mud.

The radius R3 creates an area that opposes more? effective to deformations, stiffening the flexion area, stabilizing and increasing the contact forces.

All the purposes of the invention are therefore achieved.

Claims (10)

CLAIMS 1. Sealing device (1; 1b; 100) which can be inserted between a first and a second relatively rotatable mechanical member (2,3), comprising a substantially rigid annular support (4), configured to be fixed integral with the first mechanical member (2 ), in stationary use, and an annular sealing element (5) carried integrally by the annular support and provided with at least a first annular sealing lip (8) which extends radially from the annular support (4) and which? configured to cooperate in contact and with interference with the second mechanical member (3), in rotating use; wherein the first annular lip (8) comprises, starting from a first radial edge (9) of the support, a root portion (12), an intermediate portion (13) and a head portion (14); characterized by the fact that the root portion (12) and the intermediate portion (13) have an opposite U-shape and are elastically foldable around a first (F2) and a second (F1) fulcrum defined by their respective centers of curvature so to form a bellows (15) foldable in the radial direction; the head portion (14) extending radially by cantilever from the intermediate portion (13), from the opposite side to the root portion (12) and having a snake-head conformation in radial section. 2. Sealing device according to claim 1, characterized in that the head portion (14)? axially thickened in the middle with respect to the intermediate portion (13), connecting to the intermediate portion by means of a first (16) and a second (18) curved surface, having opposite curvature and such as to define respectively, in a radial direction and towards the outside of the first sealing lip (8), a first and a second concavit? annular (19,20) shaped like a channel; the first curved surface (16) facing towards the second fulcrum (F1); and the head portion (14) tapering towards one of its extremities? free (21) facing from the opposite band to the intermediate portion. 3. Sealing device according to claim 2, characterized in that the first and second curved surfaces (16,18) have, respectively, a first (R3) and a second (R5) radius of curvature, the first radius of curvature (R3) being greater than the second radius of curvature (R5); the ratio between the first and the second radius of curvature being preferably comprised between 3.2 and 5. 4. Sealing device according to one of the preceding claims, characterized in that the head portion (14)? connected to the intermediate portion (13) through a narrow annular section (25) having a transversal thickness (SP3) less than that of the head portion (14), and a transversal thickness (SP5) of the root portion (12) measured at downstream of the first fulcrum (F2) and immediately upstream of the intermediate portion (13) and of the respective second fulcrum (F1); said restricted section (25) being configured to function as a plastic hinge constituting a third rotation fulcrum for the head portion (14) towards a loop (26) defined by the U shape of the intermediate portion (13). 5. Sealing device according to one of the preceding claims, characterized in that the head portion (14)? bounded by a band opposite the intermediate portion (13) by a first (27) and a second (28) flat annular surface, which converge towards each other from the band opposite the intermediate portion (13) to define a first edge between them sealing ring (29) of the first annular lip (8). 6. Sealing device according to claim 5, characterized in that the U shape of the root portion (12) defines a first loop (31) facing the same side as the second flat annular surface (28), while the U shape of the intermediate portion (13) defines a second loop (26) facing away from the second flat annular surface (28); the first flat annular surface (27) forming in radial section and with the parallel (p) to an axis of symmetry (A) of the first annular lip (8) a first angle (?) comprised between 30? and 50 ?; and the second flat annular surface (28) forming in radial section with said parallel to the axis of symmetry (A) of the first annular lip a second angle (?) comprised between 45 ° and 65 °. and such that the second angle? always greater than the first angle. 7. Sealing device according to one of the preceding claims, characterized in that one end? (32) of the intermediate portion (13) immediately adjacent to the head portion (14)? provided on the opposite side to the first and second fulcrum with an annular projection defining a second annular sealing edge (33) of the first annular lip (8), facing the same side as a first annular sealing edge (29) of the first annular lip , who ? configured to always cooperate in contact with the second mechanical member; the projection and the root and intermediate portions of the first annular sealing lip (8) being configured so that the second annular sealing edge (33) enters into cooperation with the second mechanical member (3) only after a predetermined radial folding of the bellows (15) formed by the root (12) and intermediate (13) portions and in such a way as to block, or delay, the flattening of the first annular sealing edge (29) as a result of an anomalous increase in interference between the first annular lip (8) and the second mechanical member (3). 8. Sealing device according to one of the preceding claims, characterized in that the ratio between a first radial distance (L1) between the second fulcrum (F1) and a first sealing edge (29) of the first annular lip (8) formed by head portion (14) and a second radial distance (L2) between the first and second fulcrum (F2, F1)? between 1.05 and 3.3; while the ratio between a first axial distance (H1) between the first sealing edge and the second fulcrum and a second axial distance (H2) between the first fulcrum and an extrados surface (34) of the U-shaped intermediate portion (13) and facing from the opposite side to the second fulcrum? between 0.7 and 1.50. Seal device (1,1b) according to any one of the preceding claims, characterized in that it comprises an annular shield (35) driven into a radially outer sleeve portion (7) of the annular support (4), opposite the first lip sealing (8); the annular shield (35) being provided with a flange portion (37) extending radially towards the first sealing lip (8) and ending with a radially internal annular edge (38) folded obliquely from the opposite band to the annular support ( 4) and arranged in a radial position substantially corresponding to that of the second fulcrum (F1). Seal device (100) according to any one of claims 1 to 8, characterized in that it comprises an annular shield (41) arranged facing the annular support (4) and configured to be keyed integral with the second mechanical member (3) and rotate relative to the annular support (4) and to the first annular sealing lip (8); a radially outer edge (42) of the annular shield being folded axially from the opposite band to the annular support (4) and being operatively associated with a radially outer sleeve portion (7) of the annular shield (4) to generate in use a centrifugation effect towards any external contaminants; the annular sealing element (5) being provided in correspondence with an intermediate portion (43) of the annular support (4) with at least a pair of second annular sealing lips (44) which axially slidingly cooperate with a corresponding intermediate portion ( 45) of the annular screen (41); the intermediate portions (43,45) of the annular shield and of the annular support being substantially parallel and facing each other and arranged obliquely with respect to an axis of symmetry (A) of the first annular sealing lip (8), being defined by portions of conical surface having conicity? facing from the opposite side to the first annular sealing lip (8).