FR2484043A1 - SEALING DEVICE FOR ROTATING SHAFT AND ASSEMBLY COMPRISING SUCH A DEVICE - Google Patents

Abstract

THE INVENTION RELATES TO A SEALING DEVICE FOR A ROTATING SHAFT AND TO AN ASSEMBLY INCLUDING SUCH A DEVICE. THIS DEVICE INCLUDES A RIGID ANNULAR MEMBRANE 18 WHOSE EXTERNAL FACE FORMING A SKIRT 18A, AND A ROTATING CAP 26 WHOSE PART FORMING A HUB 26B IS FORCE THREADED ON SHAFT 10 AND WHICH INCLUDES A PART FORMING DISC 26A TERMINATED BY A RING RETURNING 26D. A SEALING RING 20 A OF THE LIPS 22, 24 BEEN BASED ON THE HUB 26B. A FLEXIBLE FILTERING ELEMENT 33 IS INTERPOSED BETWEEN THE MEMBRANE 18 AND THE DISC-FORMING PART 26A. THE INVENTION APPLIES TO SEALING DEVICES FOR ROTATING SHAFTS PROTECTED AGAINST IRRUPTION BY FOREIGN BODIES.

Description

The present invention relates to a sealing device for a shaft

  rotating member, of the type comprising a rigid annular membrane, the outer circumferential face of which forms an axially directed cylindrical fixing skirt, and a lip seal ring made of flexible polymerized material molded on the inner circumferential edge of the membrane, and in which is provided an annular cap rotated to form sealing contact with the lip seal ring, which cap comprises an annular disk portion and a cylindrical tubular hub portion extending axially from the inner circumference of said portion forming disk in the direction opposite to said skirt, the free edge of the skirt having means forming abutments which project radially inwards, either at isolated points, or over the entire circumference, and which are provided to prevent the separation of the hat from with the

device.

  The term "rotating shaft" is intended here not only to indicate a tree as such, but also any part that can be rotated in an opening of a fixed part in which

  the sealing device in question is arranged.

  Therefore, for the purpose of the present invention, the term "rotating shaft" also includes, for example, the inner ring of a rolling element bearing, the outer ring of which then constitutes the part

fixed mentioned above.

  A sealing device of the type indicated above is the subject of the French patent application No. 79 17342 filed on July 4, 1979 by the applicant, entitled "Device

  sealing for rotating shafts ".

  The present invention constitutes an improvement of the sealing device according to this patent application and is intended to further improve the operation of this sealing device and in particular to effectively prevent the penetration of foreign bodies such as water, dust or mud in the area of the sealing lips

during the march of the device.

  In order to achieve this object, the object of the present invention is a rotary shaft sealing device of the type mentioned above, mainly characterized by the fact that between the rigid annular membrane and the rotating annular cap is interposed an annular lining of porous filter material mounted interfering axially with the annular membrane and the portion

  forming disc of rotating annular cap.

  Preferably the porous filter material of the annular liner is an elastically compressible material, for example expanded cell polyurethane foam or felt. According to the invention, the annular lining of porous filter material may be saturated with a liquid lubricant or impregnated with a

semi-solid lubricant.

  Other features of the invention will become

  apparent in the following detailed description made in

  Referring to the accompanying drawings, FIG. 1 is a partial sectional view of a sealing device according to the invention mounted in position on an associated shaft; FIG. 2 shows a first variant of the device in the free position; - Figure 3 shows the variant of Figure 2 in mounted position on a shaft; - Figure 4 shows a second variant in the free position - Figure 5 shows the variant of Figure 4 in the mounted position - Figure 6 shows another variant of the device; and

  - Figure 7 shows another variant.

  Referring to Figure 1, there is a rotating shaft 10

  mounted in a fixed support 12 by means of a ball bearing 14.

  A sealing device according to the invention is spotted in such a way

  16. In the following description, we will describe

  in detail only the parts of the sealing device 16 necessary for an understanding of the improvement according to the present invention, while to treat more completely the other parts of the device can be referred to the French patent application

No. 79 17342 mentioned above.

  The sealing device 16 comprises an annular membrane

  rigid one-piece molded piece with a cylindrical circumferential skirt

  18A. In use, the skirt 18A is forced, in a sealed manner, into the hole 12 "of the support 12 so that the free edge 18A 'of the skirt faces outwardly and preferably flush with the face 12' of the support 12. On the inner circumferential edge of the membrane 18 is molded, in a manner known per se, a rubber sealing ring 20 having a sealing lip 22 directed obliquely in a direction substantially opposite to that of the skirt 18 , while a sealing lip 24 is directed obliquely roughly in the same

direction than the skirt 18A.

  The sealing device 16 further comprises a cap 26 made of press-formed steel sheet, comprising a portion forming

  an annular disc 26A and a tubular cylindrical hub portion

  26B. In the illustrated service position, the hub 26B is forced, with sealing, on the shaft 10 so that the front face

  external disk 26A flush with the face 12 'of the support 12.

  An outer circumferential zone 26C of the disk 26A folds inwards and is joined to a cylindrical ring 26D which faces towards the membrane 18 forming a radial clearance 28 with the skirt 18A. As can be seen in the drawing, the lips 22, 24 are both in sealing relationship with the outer cylindrical surface of the hub 26B. The radial clearance 28 is sufficiently small to prevent excessive deformation of the lips 22, 24 due to possible radial displacements of the cap 26. The axial separation of the cap 26 from the annular membrane 18 is avoided by a series of axial stops in the form of 18A "folded ears which are cut radially inwards in the free edge 18A 'of the skirt 18A It will be seen from the drawing that, in the illustrated use situation, the ring 26D is in an intermediate position between the diaphragm 18 and the folded ear 18A ", with formation of axial clearances 30, 32 with these parts, these clearances being necessary to allow the rotation of the cap 26 with the shaft 10. Notwithstanding the fact that the dimensions of these axial games 30, 32 are rather limited, there is a possible risk of penetration of foreign material such as water, dust or mud, from the outside, into the interior of the device 26, with consequent possible interruption of the sealing contact between the two lips 22 and 24 and the cylindrical surface

  outer hub 26B. To avoid this risk and to ensure

  Perfectly the device under any operating conditions whatsoever, according to the invention is interposed between the rigid annular membrane 18 and the annular cap 26 an annular packing 33 of porous filter material. As can be seen clearly in the drawing, the annular liner 33 has, in cross section, a shape complementary to that of the zone it

  occupies in the space between the annular membrane 18 and the cap 26.

  The liner 33 is made of a porous, plastically compressible filter material, for example expanded open cell polyurethane or felt, and has, in its undeformed state, that is to say before being mounted, a thickness slightly greater than the distance between the membrane 18 and the surface of the cap 26 facing it on the other side of the area occupied by the gasket 33 when mounted in position. In this way, when the annular seal 33 is mounted in position, it is slightly compressed axially between the annular membrane 18 and the cap 26, that is to say between the front surfaces of the annular seal 33 and the surfaces. corresponding diaphragm 18 and the cap 26 facing it, there is axial interference. Moreover, the greater part of the outer circumferential surface of the annular liner 33 radially interferes with the inner surface of the outer cylindrical ring 26D

  26. In this way the remaining part of the circumferential surface

  outer ring seal 33 penetrates slightly into

  the axial clearance 30 located between the ring 26D and the membrane 18.

  To reduce the sliding friction between the outer surface of the annular liner 33 and the corresponding surfaces of the membrane 18 and / or the cap 26, and to further improve the filtering power of the material which constitutes the lining 33, this lining 33 is of. preferably saturated with a lubricating oil or

  impregnated with a semi-solid lubricant, for example a graphitized grease.

  In use, it prevents the lubricant from escaping into the interior of the support 12 through the sealed contact of the lip 22 (inner sealing lip) with the hub 26B, while it prevents the penetration of the water or other materials from the outside both by the sealing contact of the lip 24 (external sealing lip) with the hub 26B itself and by the presence of the seal

annular 33.

  In Figures 2 and 3, the parts corresponding to those which have already been described in relation to Figure 1 have been identified with the same reference number, increased by 200. In this variant, the internal sealing lip 222 is still located in sealing relationship with the outer cylindrical surface of the hub 226B as in Fig. 1, while on the other side the outer sealing lip 224 is molded into a cup-shaped lip to make a contact sealing face with the inner face (smooth and polished) of the disk portion 226A of the cap 226. The

  annular seal 233 of the porous filter material is substantially

  similarly to that described in connection with Figure 1 and in this case an additional function, in the free state that is to say before mounting the device on the shaft, to prevent the lip 224 does not undergo excessive crushing by the disk 226A during handling of the device. In the assembled state shown in FIG. 3, the annular lining 233 is in slight axial compression of the

  same way as in the previous case.

  In FIGS. 4 and 5, the parts corresponding to those already described with reference to FIG. 1 are marked with the same reference number increased by 400. In this variant, the lips 422, 424 are arranged in such a way that to form a seal with respect to the front inner face of the disc portion 426A of the cap 426. Again in this case, the thickness of the annular seal 433 is such as to prevent the cap 426 from being subjected to excessive displacements so that the lips 422 and 424 are not subjected to excessive deformation due to the displacements of the disc 426A when the device is handled in the free state,

  that is to say, not mounted as shown in Figure 4.

  In FIG. 6, the parts corresponding to those already described with reference to FIG. 1 are marked with the same reference number increased by 600. In this variant, the "shaft" component is represented by the inner ring 610 of a bearing. balls, while the fixed part is represented by the outer ring 612 of the same bearing and the sealing device according to the invention has the role of sealing between the two said rings. The lips 622 and 624 are arranged in frontal sealing configuration as in FIGS. 4 and 5. Unlike the previous embodiments, however, the 626C inwardly-fitting portion of the cap 626

  ends with a radially directed circumferential edge 626C '.

  In addition, instead of the stop lugs 18A "of FIG.

  uses here a stop ring 40 housed in a circumferential groove

  internal core of the skirt 618A of the membrane 618.

  In this case, the annular seal 633 of porous filter material is interposed interfering axially between the annular membrane 618 and the circumferential edge 626C 'of the annular cap 626 and its outer circumferential surface comes in radial compression.

  against the circumferential skirt 618A of the membrane 618.

  In FIG. 7, the parts corresponding to those already described with reference to FIG. 1 are marked with the same reference number increased by 700. In opposition to the previous embodiments, the cap 726 is not provided now with a part

  which is folded axially in the space surrounded by the skirt 718A.

  The lips 722 and 724 are held in radial sealing contact with the surface of the hub 726B by means of a toroidal coil spring 42. Moreover, in this variant, the annular seal 733 of porous filter material interferes axially with the annular membrane 718 and with the disc 726A of the cap 726, while its outer circumferential surface comes in radial compression.

  against the cylindrical skirt 718A of the annular membrane 718.

  Naturally, the effects of the present invention extend to embodiments that have the same function using the same innovative concept. The described embodiments are in no way

limiting of the invention.

2484U43

Claims (10)

  1. Sealing device for rotating shaft, of the type   comprising a rigid annular membrane, whose circumferential face   outer ring forms an axially directed cylindrical fixing skirt, and a lip seal ring of flexible polymerized material molded on the inner circumferential edge of the membrane, and wherein there is provided an annular cap rotated to form a sealing contact. with the lip seal ring, which cap comprises an annular disk portion and a cylindrical tubular hub portion extending axially from the inner circumference of said disk portion in the opposite direction to said skirt, the free edge of the skirt having abutment means which project radially inwardly, either at isolated points or over the entire circumference, and which are provided to prevent separation of the cap from the device, characterized in that between the rigid annular membrane and the annular rotating cap is interposed an annular pad of maté Porous filter material mounted by interfering axially with the membrane   annular portion and the disc portion of the rotating annular cap.   2. Device according to claim 1, wherein the outer circumferential face of the annular disc portion of the rotating cap comprises a cylindrical ring which penetrates axially into the space that surrounds the skirt, with a radial clearance with respect to this skirt, characterized in that the outer circumferential surface of the annular lining of the porous filter material comes radially in pressure against said cylindrical ring outer of the rotating cap.   3. Device according to claim 1, characterized in that the outer circumferential surface of the annular lining of the porous filter material comes radially in pressure against the skirt.   cylindrical fixing of the rigid annular membrane.   4. Device according to claim 1, characterized in that the porous filter material of the annular lining is a material Plastically compressible.   5. Device according to claim 4, characterized in that the porous filter material of the annular lining is   expanded polyurethane with open cell.   6. Device according to claim 4, characterized in that   the porous filter material of the annular liner is felt.   7. Device according to any one of claims 1 to 6,   characterized in that the annular lining of filter material   porous is saturated with a lubricating liquid.   8. Device according to any one of claims I to 6,   characterized in that the annular liner of the porous filter material   is impregnated with a semi-solid lubricant.   9. Device according to claim 8, characterized in that   the semi-solid lubricant is a graphitized grease.   10. An assembly comprising a shaft rotating in a support, characterized in that it comprises a sealing device according to one   any of claims I to 9.