Abstract:
The invention relates to a device for sealing a gap between parts that are moved relative to one another, namely a fixing part, for fixing at least one elastic sealing element at an edge thereof, and a stop part along which another edge of at least one elastic sealing element runs, wherein the fixing part comprises, running along the gap, at least one groove in which are inserted one or more anchoring parts that engage through or around the sealing element and/or a retaining element that retains same.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a device for sealing a gap between parts that are moved relative to one another, namely a fixing part to which at least one elastic sealing element is fixed by one of its edges, and a stop part along which another edge of at least one elastic sealing element runs. 
         [0003]    2. Description of the Prior Art 
         [0004]    Gaps between parts that are moved relative to one another are usually sealed by means of linear or annular elastic sealing elements, preferably having a substantially flat cross section, i.e., a ribbon-shaped structure bounded by two longitudinal edges. To fix them in place, the sealing elements are inserted by a preferably broadened longitudinal edge in a groove extending parallel to the gap and provided in one of the two parts to be sealed, referred to hereinafter as the fixing part, and are thereby fixed, while their opposite longitudinal edge grazes along the respective other one of the two parts, referred to hereinafter as the stop part, and thereby seals the gap. 
         [0005]    The gap to be sealed between two parts that are moved relative to each other is often filled with a lubricant, particularly grease, which is to be held in place by the elastic sealing element. A sealing element inserted in a groove is usually also able to perform this function. Under some circumstances, the lubricant can also be pressurized to enhance the lubricating effect. But sealing elements that are anchored as described, by being inserted in a groove, can rarely stand up to the resulting pressure differential; they are almost always lifted out of their anchoring groove until they yield and allow lubricant to escape, resulting in a pressure drop. 
       SUMMARY OF THE INVENTION 
       [0006]    From the disadvantages of the described prior art comes the problem initiating the invention, to design a device for fixing elastic elements such that the elements can withstand a pressure differential even on the order of one or more bars without leaking. In addition, the technical expenditure for such an anchoring system should be as low as possible. 
         [0007]    The solution to this problem is achieved by the fact that in a seal of the generic kind, the fixing part comprises, running along the gap, a groove in which are inserted one, or preferably more, anchoring parts that engage through or around the sealing element and/or a retaining element that retains same. 
         [0008]    With an arrangement of this kind, the invention achieves the actually competing goals of particularly firm anchoring, on the one hand, and the lowest possible technical expenditure, on the other. A groove is provided in the fixing part, as before, but there is no need either to bore individual anchoring holes or to cut thread. The anchoring elements can be prefabricated in a standardized manner and secure the elastic sealing element form-lockingly. 
         [0009]    It has proven advantageous for the extent of a portion of an anchoring part that engages in the groove to be, in the longitudinal direction of the groove, equal to or less than twice the maximum width of the groove, preferably equal to or less than one and a half times the maximum width of the groove, thus, in particular, making it possible to minimize the weight of such an anchoring part. 
         [0010]    Such anchoring parts preferably are not packed tightly together but are spaced apart, for example, by a distance that is greater than their extent in the direction of the groove, preferably twice or more as great as their extent in the direction of the groove, and in particular at least three or four or even five times or more as great. 
         [0011]    It has proven beneficial for the extent of the core of a portion of an anchoring part that engages in the groove to correspond, in the longitudinal direction of the groove, to approximately the width of the groove. “Core” here signifies in particular a mathematical body, for example a cylinder, that is inscribed in a surface structure such as, for example, a thread, i.e., the anchoring body “minus” the surface structure. In the case of a screw thread, therefore, the size corresponds to the core diameter of the thread. 
         [0012]    The invention further provides that an anchoring part is configured as a threaded bolt or a screw, preferably as a machine screw, particularly as a machine screw with a self-tapping thread. Such a machine screw can be screwed into the anchoring groove, according to the invention, transversely to the longitudinal direction of the groove, in which case the screw thread automatically cuts the necessary internal thread segments into the flanks of the groove. The then mating thread segments ensure reliable anchoring of the screw in the groove. 
         [0013]    An alternative embodiment to the foregoing is characterized by the fact that an anchoring part is configured as a rivet, particularly a blind rivet, whose inner head is disposed in an undercut region of the groove, that is, a region that is broadened in relation to the groove aperture. The inner rivet head thus provides form-locking anchoring of the rivet in the anchoring groove, while the upper or outer rivet head also form-lockingly overlaps the elastic sealing element, or a fixing element that retains the latter. 
         [0014]    An anchoring part can also be configured as a sleeve which is pushed onto, or can be slid onto, a core. In this case, the core stabilizes the sleeve and/or deforms it on being inserted in a suitable manner to achieve stable anchoring. 
         [0015]    The invention can be developed further by having the core broaden to the bottom of the groove, so as to expand a pushed-on sleeve in the region of the bottom of the groove and thereby anchor the sleeve. 
         [0016]    It is within the scope of the invention that a portion of an anchoring part provided for engagement in the groove has a rotationally symmetrical cross section, apart from any thread disposed thereon. Such a structure facilitates the insertion of the anchoring part, since the latter need not be aligned parallel to the longitudinal direction of the groove before being inserted. 
         [0017]    In one particular embodiment, a portion of an anchoring part for engagement in the groove has an elongated cross section that allows it to be inserted when rotated in the longitudinal direction of the groove and to be anchored against an undercut of the groove when rotated transversely to the longitudinal direction of the groove. Even though anchoring takes place via a rotating movement, the resulting anchoring is still reliable and features very high retention force. 
         [0018]    An elastic sealing element can be firmly clamped to a surface of the fixing part. This means, for example, that a region of the surface of the sealing element rests flat against the surface of the fixing part and is pressed thereagainst by the anchoring parts to create a friction lock, thus fixing it in place. 
         [0019]    Alternatively, it is also possible for an elastic sealing element to be firmly clamped in a fillet of the fixing part. The position of the sealing element is also specified in this way, since it cannot release itself from the fillet on its own. 
         [0020]    In the context of another embodiment of the invention, it can be provided that an elastic sealing element engages in a groove-shape depression of the fixing part and is preferably firmly clamped therein. This can be the same groove in which one or more anchoring parts, for example, one or more screws or rivets, engage and are anchored. The sealing element is then merely recessed or interrupted at the respective positions of the anchoring parts. Such a recess can, for example, be in the shape of a hole and be created, preferably manually, with the aid of a simple tool, for example, a hole punch or a knife. If an anchoring part is used that has a formed-on tip at the end directed toward the bottom of the groove, a recess of this kind is no longer necessary. In such cases, the rubber material of the seal can instead be bored through and/or supplanted by screwing in a screw or hammering or driving in a rivet. Under these circumstances, when the seal is to be replaced, a new screw or a new blind rivet can be inserted at any desired location in the groove; it is not necessary for such a screw or blind rivet to be inserted at the “old” position. 
         [0021]    A fixing element—a flat such element, for example—can be firmly clamped to an outer face of an elastic sealing element. It then assumes the function of pressing the actual sealing element friction-lockingly against the fixing part. In this case, the sealing element itself need not be penetrated by the anchoring parts. 
         [0022]    Another way of anchoring a fixing element is to firmly clamp the fixing part in a fillet. The desired position of the fixing element can be precisely specified and adhered to in this way. 
         [0023]    According to the invention, an elastic sealing element and/or a fixing element can be composed of a plurality of mutually separate segments. These need not be joined together, but may optionally merely be fixed one after the other in a row, particularly by means of the anchoring parts according to the invention. Such segments of a fixing element can be, for example, a flat metal part (particularly of sheet metal), laser-cut strips, or punched tape. 
         [0024]    The anchoring groove according to the invention can extend within a plane. In such cases it can follow a straight path or—as will be explained in more detail below—a curved, particularly a circular, path. The relative movement of the two parts to be sealed preferably takes place within this plane, i.e., the respective plane is not departed from during movement. 
         [0025]    A special case arises with regard to sealing when the fixing part and the stop part are rotatable relative to each other about an axis of rotation. Rotational movements are not subject to any limitations and can therefore last almost indefinitely, so they present particular challenges in terms of obtaining a reliable seal. 
         [0026]    The invention is also suitable for situations in which the axis of rotation of the mutually rotatable parts extends obliquely and/or perpendicularly to the plane of the groove. The inventive anchoring of a sealing element secures it both parallel to and transversely to its longitudinal or circumferential direction. For this reason, the orientation of the axis of rotation between the mutually rotatable parts is not a constraint for the sealing system according to the invention. 
         [0027]    The invention recommends a sealing device of the generic kind, particularly when the fixing part and/or the stop part is/are each configured as a rotating part. In such cases, the sealing element can be configured as a self-contained biconnected element that runs along the annular gap. Even an endless sealing element of this kind is reliably anchored by the technique according to the invention. 
         [0028]    A further design specification provides that the fixing part and/or the stop part is/are each configured as a ring, particularly having a circular shape, corresponding to a sealing element having an annular structure. 
         [0029]    Finally, it corresponds to the teaching of the invention that one or more rows of rolling bodies are disposed in the gap between the stop part and the fixing part. The rolling bodies serve the purpose of keeping the width of the gap constant and/or of orienting the base planes of the two parts relative to one another, particularly aligning them in parallel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Further features, details, advantages and effects based on the invention, will emerge from the following description of a preferred embodiment of the invention and by reference to the drawings, wherein 
           [0031]      FIG. 1  is a section through a rotating bearing with a sealing element fixed according to the invention; 
           [0032]      FIG. 2  illustrates another embodiment of the invention, also in section; 
           [0033]      FIG. 3  is an illustration corresponding to  FIG. 2  of a further-modified embodiment of the invention; 
           [0034]      FIG. 4  is another modified embodiment of the invention, also in an illustration corresponding to  FIG. 2 ; and 
           [0035]      FIG. 5  is another modified embodiment of the invention in an illustration similar to  FIG. 2 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    The rotary joint  1  depicted in  FIG. 1  comprises an outer ring  2  (shown by way of example on the left in  FIG. 1 ) and an inner ring  3  (shown on the right in  FIG. 1 ) disposed concentrically inside the outer ring. Each of the two rings  2 ,  3  is provided with a generally rectangular cross section. The inner jacket surface  4  of the outer ring  2  is provided with a slightly larger diameter than the outer jacket surface  5  of the inner ring  3 , thus resulting in a circumferential gap  6  between them. Provided in, particularly machined into, each of the facing jacket surfaces  4 ,  5  is a respective circumferential depression  7 ,  8  with a constant, preferably approximately circular-shaped, cross section. A row of rolling bodies, for example balls  9 , can roll therein to permit relative rotation between the two rings  2 ,  3 . The axis of rotation about which the rings  2 ,  3  rotate relative to one another is shifted far to the right of the drawing of  FIG. 1 , and is therefore not visible in the drawings. To make it possible to connect the rings  2 ,  3  to a respective adjacent construction (machine part, system part, vehicle part, frame or foundation), each ring  2 ,  3  is provided with a row of fixing bores  10 ,  11  extending parallel to the axis of rotation and distributed around the axis of rotation in a ring shape. These can be configured as through-bores or threaded blind bores. To make it easier to screw the two rings  2 , 3  to different system parts, the two rings  2 ,  3  are slightly offset from each other in the axial direction of the axis of rotation, with the result that, for example, at the upper (in  FIG. 1 ) end face of the rotary joint  1 , the one ring—in the example illustrated, inner ring  3 —projects beyond the other ring—here, outer ring  2 —thereby creating a kind of step configuration at the gap  6 , i.e., a region where the outer jacket surface  5  of the inner ring  3  projects upward above the gap  6 , unlike the inner jacket surface  4  of the outer ring  2 . 
         [0037]    The gap  6  is preferably filled with a lubricant, particularly grease. To keep the lubricant in the gap and protect it against the ingress of particles, the gap  6  is sealed at one, or preferably both, narrow sides. In the embodiment according to  FIG. 1 , this function is assumed by a flexible sealing element  12  in the form of a closed ring of flexible and elastic material, for example vulcanized, natural or synthetic rubber. The circumference of the sealing element  12  approximately corresponds to the length of the gap  6 . Sealing element  12  preferably exhibits a ribbon shape with an elongated cross section, as can be seen in  FIG. 1 , comprising two flat sides  13 ,  14  joined together by two narrow sides  15 ,  16 , which can also be configured as longitudinal edge(s). The cross section can, in particular, taper to one narrow side  16 , so that a sealing lip is formed there. The sealing element  12  is also pierced by a plurality of perforations  17 , particularly extending from one flat side  13  to the other flat side  14 . 
         [0038]    To fix the sealing element  12  to one of the two rings  2 ,  3 —to inner ring  3  in the illustrated example—provided in the region of outer jacket surface  5  of inner ring  3  that projects upward above the gap  6  is a fully circumferential groove  18 , preferably of rectangular cross section, whose flanks  19  extend in mutual parallelism approximately to the groove bottom  20 . The width of the groove  18  approximately corresponds to the diameter of the perforations  17  in the sealing element  12 . The distance from the lower groove flank  19  to the gap  6  is smaller than the distance from the perforations  17  of the sealing element  12  to its bottom narrow side  16  or sealing lip. 
         [0039]    The sealing element  12  is fixed to the inner ring  3  by means of screws  21 , particularly machine screws, which are inserted each through a respective perforation  17  of the sealing element  12  and are then rotated into the groove  18 . The screws  21  are preferably provided with a self-tapping thread  22 , i.e., as the screws  21  are rotated into the groove  18 , each screw creates its own suitable internal thread segments in the groove  18 , specifically in the groove flanks  19  locally, and these internal thread segments interact durably with the screw thread  22  and durably fix the screws  21  in the groove  18 . It is advantageous for this purpose that the core of the screws  21  is equal to or less than the width of the groove, or the distance between the two groove flanks  19 , whereas the outer circumference of the thread region  22  should be greater than the distance between the two groove flanks  19 . In addition, the material of the screws  21  should be at least as hard as the material of the particular ring  3 , and preferably harder. For this reason, it has proven beneficial to surface-harden the particular ring  3 , at least locally in the vicinity of the depression  8 , but not to through-harden it. 
         [0040]    While this fixing causes a flat side  14  of the sealing element to be pressed against the surface of the particular ring  3 , at least in the vicinity of the perforations  17 , for example against the projecting region of a jacket surface, particularly the outer jacket surface  5  of inner ring  3 , screw heads  23  engage over the outwardly disposed flat side  13  of the sealing element  12 , i.e., the side facing away from the particular ring  3 . To keep the screw heads  23  from slipping through the elastic material of the sealing element  12 , a thrust ring  24 , preferably consisting of a firm material such as, for example, metal, can be disposed between the outer flat side  13  of the sealing element  12  and the screw heads  23  gripping it; under some circumstances, the thrust ring  24  can also be composed of a plurality of segments, which need not be joined together. The thrust ring  24  preferably has the same circumference as the annular sealing element  12 , and also resembles it by having a ribbon-shaped structure with an elongated cross section. The width of the flat sides  25  of the ribbon-shaped thrust ring  24  is, however, slightly narrower than the width of the flat sides  13 ,  14  of the ribbon-shaped sealing element  12 . In addition, the thrust ring  24  comprises perforations  26 , each of which preferably corresponds in dimensions and position to a respective perforation  17  in the sealing element  12 , so that a respective screw  21  can be engaged through both together. Due to the thrust ring  24 , the pressure force of the screw heads  23  is distributed over a large area, specifically over the entire flat side  25  of the thrust ring  24 , thus reliably preventing damage to the sealing element  12  and keeping the screws  21  from slipping through their perforations  17 . The screw heads  23  can be compassed at their periphery by a standard hexagon and/or provided at their free end face with a slot or cross slot. The thrust ring  24  may be unnecessary if screws  21  with a very large diameter screw head  23  are used. 
         [0041]    In the context of the arrangement according to  FIG. 1 , in the illustrated variant, the inner ring  3  serves as a fixing part in the sense of the invention, whereas the outer ring  2  is used as a stop ring. It would also, of course, be possible instead to fix a sealing element to the outer ring  2  and have its sealing lip graze along the inner ring  3 , if, for example, the outer ring  2  is raised relative to the inner ring  3  in the region of the underside of the rotary joint  1 . In general, the issue of whether the inner ring or an outer ring serves as the fixing part is not crucial for the fixing of the sealing element within the scope of this application. 
         [0042]      FIG. 2  shows an embodiment of the seal that has been modified with respect to the foregoing. The rotary bearing  1 ′ shown differs from the one previously described only in the manner of fixation of the annular sealing element  12 ′. Here, in contrast to the previously described embodiment, the latter element does not rest against the jacket surface of the respective end face of the raised ring which faces the gap of the ring, but rather, against the end face  27  of the ring that is offset in the axial direction, i.e., in the case of  FIG. 2 , the end face  27  of inner ring  2 ′ shown on the left. There, a fully circumferential groove  28  is present, into which the screws  21 ′ are turned as in the previously described embodiment. The relative dimensions of the groove  28  and the screws  21 ′ are the same as in the embodiment according to  FIG. 1 . Here again, a thrust ring  24 ′ can be provided, whose cross section can correspond to that of the thrust ring  24  from  FIG. 1 . In all cases, the axis of curvature about which both the sealing ring  12 ,  12 ′ and the thrust ring  24 ,  24 ′ are curved corresponds to the axis of rotation of the rotary bearing  1 ,  1 ′. It should, of course, be kept in mind that in the case of the thrust ring  24  according to  FIG. 1 , the axis of curvature is oriented parallel to the particular ring cross section, whereas in the case of the thrust ring  24 ′ of  FIG. 2 , it is oriented approximately perpendicular to the ring cross sections. Although this has virtually no significance for the flexible sealing element  12 ,  12 ′, it should be noted in regard to the relatively firm or rigid thrust ring  24 ,  24 ′, that the latter can be bent from a straight ribbon in the case illustrated in  FIG. 1  and then welded, or soldered, to form a ring  24 ; ring  24 ′, on the other hand, is to be punched into a ring shape from sheet metal. 
         [0043]    The arrangement of a rotary bearing  1 ″ according to  FIG. 3  represents a modification of the arrangement from  FIG. 2 . The annular sealing element  12 ″ is received in a fillet  29 , which is machined into the region of the edge between the set-back end face  27 ″ and jacket surface  4 ″ of the particular ring—here, outer ring  2 ″—which faces the gap  6 ″, and which can have an approximately rectangular to nearly square cross section. The thrust ring  24 ″ has a greater width and extends from groove  28 ″, located to one side of the fillet  29 , all the way across the fillet  29  and covers it, except for a narrow gap  30  relative to the jacket surface  5 ″ of the facing ring—here, inner ring  3 ″. 
         [0044]    In this embodiment  1 ″, the annular sealing element  12 ″ is provided with a cross section with two legs  31 ,  32  that form an acute angle with each other. One leg  32  bears, on its outer side facing away from the other leg  31 , a preferably obtuse-angled sealing lip  33 , which runs along the jacket surface  5 ″ of the non-filleted ring  3 ″. The sealing lip  33  can be pressed against the jacket surface  5 ″ serving as the stop surface by a fully circumferential tension wire  34  that extends tautly around leg  32  on the opposite side of the leg from the sealing lip  33 . The other leg  31 , in contrast, serves primarily to positionally fix the sealing element inside the fillet  29 . To this end, the cross-sectional length of this leg, measured parallel to the axis, approximately corresponds to the height of the fillet  29  measured parallel to the axis. The leg  31  can also be embodied as more massive than the leg  32  bearing the sealing lip  33 . 
         [0045]    Embodiment  1   (3)  according to  FIG. 4  can be seen as a combination of the sealing arrangements according to  FIGS. 2 and 3 . It includes two sealing elements  12   (3) ,  35 , disposed one above the other in the axial direction, both of them fixed to the same ring—in the present example, inner ring  2   (3) —and both grazing along the other ring—in the present example, outer ring  3   (3) . Upper sealing element  12   (3)  here is identical to sealing element  12  from  FIG. 2 ; the thrust ring  24   (3)  and the screws  21   (3)  also correspond to the arrangement of  FIG. 2 . As in that case, here again the groove  28   (3)  is machined into the end face  27   (3)  of the ring  2   (3)  that is set back in the axial direction. 
         [0046]    Similarly to the embodiment according to  FIG. 3 , a filleted region  29   (3)  is also present here in the region between the set-back end face  27   (3)  and the adjacent jacket face  4   (3) . In this variant, however, the fillet is not provided with a rectangular cross section, but rather a stepped cross section resembling a staircase with two steps  36 ,  37 , the top step  36  being farther away from the gap  6   (3)  than the bottom step  37 . The groove  28   (3)  in this embodiment is not located next to the fillet  29   (3) , but passes through the top step  36  of the fillet  29   (3) . 
         [0047]    A sealing ring  35  with an elongated, optionally rectangular, cross section rests on the bottom step  37  of the fillet  29   (3) . Since this sealing ring  35  is mounted with its cross section horizontal, the sealing ring  35  can be characterized as an annular disk. This arrangement can be devised such that that jacket surface  5   (3)  of the opposite ring  3   (3) , which serves as the stop face, has a fully circumferential groove  38 , for example, of rectangular cross section, at the level of this sealing ring  35 . The region of the sealing ring  35  near its free longitudinal edge or narrow side  39  can engage in this groove  38 , thus creating not only friction-locking contact, but also, effectively, form-locking contact. 
         [0048]    The sealing ring  35 , whose height corresponds generally to the height of the bottom step  37 , is covered by a spacer ring  40  placed on the top step  36  and is thereby held in position. The screws  21   (3)  pass through the spacer ring  40 , along with the upper sealing element  12   (3)  and the thrust ring  24   (3)  disposed thereon, and screw their thread into the groove  28   (3) . Under some circumstances, the spacer ring  40  may be composed of a plurality of segments that need not be joined together. 
         [0049]    Since the lower sealing ring  35  is fixed form-lockingly in the fully circumferential, groove-shaped depression  38 , this seal can durably withstand even relatively large pressure differences between the gap  6   (3)  and the external environment. 
         [0050]    The arrangement according to  FIG. 5  represents a modification of the arrangement according to  FIG. 2 . The arrangement of the stepped rings  2   (4) ,  3   (4)  and the gap  6   (4)  between them, together with the sealing element  12   (4)  and the thrust ring  24   (4) , is completely identical to the arrangement from  FIG. 2 . The position of the fully circumferential groove  28   (4)  also corresponds to the arrangement according to  FIG. 2 . However, the flanks  41  of the groove  28   (4)  are not straight in this case, but broaden, particularly in stepwise fashion, to the groove bottom  20   (4) , thus forming an undercut. 
         [0051]    The sealing element  12   (4) , together with the thrust ring  24   (4) , is fixed in this groove  28   (4)  not with screws, but with blind rivets  42 . Each blind rivet  42  comprises a sleeve  43  and a pin  44 . At its end inserted in the groove  28   (4) , the pin  44  is provided with a thickening  45 . Once the sleeve  43  has been mated onto and positioned on the pin  44 , the thickening can be pulled into the sleeve  43  and widens it, causing it to expand into the undercut region of the groove  28   (4)  and thus be anchored form-lockingly in the groove  28   (4) . The portion of the pin  44  that is pulled out of the sleeve  43  in the process ultimately breaks off, and the free end of the sleeve  43  is hammered flat in the customary manner and thus grips the sealing element  12   (4)  and the thrust ring  24   (4)  resting thereon. 
         [0052]    Such blind rivets  42  can be used in place of the above-described screws  21  in all of the embodiments described hereinabove, as well as in other applications of the invention. 
         [0053]    It should be noted that the invention can naturally be used not just for rotary bearings, but also for other parts that are moved relative to one another, regardless of whether they are rotated or moved linearly with respect to one another.