GB2066379A

GB2066379A - Pedestal bearing housing means

Info

Publication number: GB2066379A
Application number: GB8040662A
Authority: GB
Original assignee: Kuhbier & Co
Current assignee: Kuhbier & Co
Priority date: 1979-12-28
Filing date: 1980-12-18
Publication date: 1981-07-08
Also published as: BE886881A; NL8006515A; IT1134894B; FR2482222A1; DE2952638A1; SE8009063L; IT8026938A0

Abstract

Pedestal bearing housing means of plastics material comprises an upper housing half shell (1) and a lower housing half shell (2) which can be assembled around a pivot bearing by being plugged together. The two shells (1, 2) during plugging together interengage in such a manner as to be positively mechanically locked together. For this purpose, formed laterally on one of the shells (1) are resilient snap-in detent means (4, 5, 16) which, during plugging together of the shells, snap into corresponding snap-in detent means (6, 7, 17) on the other shell (2) and provide a mechanical and pressurable intercoupling of the two shells (1, 2). <IMAGE>

Description

SPECIFICATION Pedestal bearing housing means The present invention relates to pedestal bearing housing means of plastics material for a pivot bearing.

Pedestal bearing housings composed of upper and lower housing shells are known. It has not been possible to make plastic pedestal bearing housing for a pivot bearing in one piece. All known plastics material pedestal bearing housings for pivot bearings are produced in two shells and the bearing introduced between these shells before assembly of the shells. One-piece pedestal bearing housings were hitherto known only in cast metal construction. For introduction of a bearing laterally into the bearing chamber of such a bearing housing, two grooves are provided at one chamber side on a diagonal of the chamber and have a spacing from groove bottom to groove bottom corresponding to the greatest chamber diameter.

After the bearing has been pushed laterally in through the opening created by the grooves, it is turned round and brought into its operative position.

This plug-in method has several disadvantages.

In order not to weaken the material too much, the grooves must be as narrow as possible; longer bearing sleeves and other widened parts of a bearing cannot be introduced. Moreover, the precision of the bearing housing is reduced by the grooves and the grooves represent ideal entries for dirt and dust.

Two-piece bearing housings are in little demand because the housing parts are screwed together in the course of assembly (to a bracket or the like) and this screw connection often gradually loosens due to operational vibrations and shocks.

Once the connection has loosened, the tightness of the assembly of the two bearing housings is also loosened, which rapidly leads to destruction of the housing and bearing.

On the other hand, the mounting of, in particular, longer shafts with several successive bearing locations poses difficult problems with respect to the alignment of the bearing axes.

When the bearing axes are not exactly aligned in the alignment direction, friction points arise in the bearing and lead to heat development and dry running which in time destroys the bearing. In order to avoid angular deviations from the alignment direction, it has been the practice, even with rigid shafts, to use pivot bearings or other bearings with a degree of pivotal freedom. The pivot bearing desired by the market cannot, however, be introduced into a one-piece plastics material pivot bearing housing, because a suitable housing, for example with grooves, cannot be manufactured by known injection techniques.

A further problem with the known pivot bearing housings is that it is not possible in terms of production technique to produce spherical surfaces sufficiently precisely, at a price acceptable to the market, in order to provide an exact support for the outer ring of the bearing at the spherical inside wall of the bearing chamber. If the diameter of the outer ring is greater than the smallest diameter of the bearing chamber at one or more points, the bearing is clamped in too hard during the fastening of the bearing housing, which causes the bearing to jam and to heat up. Due to the fact that the bearing runs heavily, the inner ring stresses the outer ring through the balls or rollers. If, however, the largest diameter of the outer ring is smaller than the smallest diameter of the bearing chamber, then the running ring is loosely seated.This problem exists in cast housings as well as in plastics material housings.

A solution to these problems is described in DE OS 28 00 648, which discloses the formation of radial grooves in the bearing chamber wall so as to provide ribs which ar raised a few tenths of a millimetre above the groove bottoms. When the bearing is clamped in the bearing chamber, the diameter difference at the spherical surfaces balance one another so that the spherical surface of the outer ring at places presses in the ribs to cause the plastics material of individual ribs to flow into neighbouring grooves. As a result there is provided a firm, but not too firm, seat of the bearing in the bearing chamber.

However, this measure has only been possible with two-piece pivot bearing housings which are held together by means of fastening screws and thus exhibit the previously described disadvantages.

There is therefore a need for a two-part plastics material pedestal bearing housing for a pivot bearing, which is not assembled with screws and not assembled in such a manner that it can be adversely affected by shocks. The means for holding the bearing housing parts together should be independent of fastening means fastening the bearing housing to its supporting bracket or the like. Accordingly, the bearing housing should be capable of assembly before installation and of receiving a pivot bearing during assembly, and should through its subsequent indivisibility be equivalent to a one-piece bearing housing.

According to the present invention there is provided pedestal bearing housing means of plastics material comprising a base shell member and a cover shell member which are interengageable to form a housing for a pivot bearing and which are provided with laterally disposed complementary detent means adapted to so resiliently snap into interengagement on said interengagement of the shell members as to pressurably and mechanically lock the shell members together.

The shell members may be produced not only with smooth bearing chamber walls, but also with grooved bearing chamber walls according to the previously mentioned DE-OS 28 00 648. With bearing housing means embodying the invention it may be possible to create not only assemblable bearing housings which, after the shell members have been assembled around a bearing, cannot be taken apart without destruction, but also, in the alternative, to produce assemblable bearing housings which can be taken apart without destruction before mounting or after demounting.

In the mounted state, such housings are effectively equivalent to one-piece housings in that the mounting of the bearing in the bearing chamber of the housing cannot be altered through loosening of fastening screws as a result of shocks or temperature change.

The cover shell member is preferably constructed in the form of a resilient bow, the limbs of which resiliently encompass the middle part of the base shell member, wherein arranged at the inner surface portions of the limbs are projections which, under the influence of the spring force, snap into corresponding grooves in outer surface portions of the middle part of the base shell member.

Preferably, the separating plane which, after interengagement of the two shell members defines their contact surfaces, extends at first parallelly to a support surface of the base shell member and through the axis of the bearing chamber, then extends at both sides of the bearing chamber towards the support surface, and finally passes over into contact surfaces of fastening flanges of the shell members. Expediently, formed on one of the shell members at each side of the bearing chamber is a respective rail which extends parallelly to the bearing chamber axis and which, on interengagement of the shell members, enters into a corresponding groove in the other shell member, a recess of substantially the same width and length as the recess preferably being provided beside each recess.In this case, chamfers can be provided at entrances of the recesses to define, in cross-section, a V-shaped groove which corresponds with a respective locking projection having a corresponding V-shaped cross-section and provided on said one shell member.

In another advantageous embodiment, the rails are constructed to be inherently resilient and a respective recess is arranged beside each rail, the recess being of substantially the same length and width as the rail but somewhat deeper than this is thick. Each recess receives the respective rail on resilient pivoting of the rail and intersects a respective fastening bore. Formed at a free end of each rail can be an enlarged reinforcement which in the unstressed setting of the rail projects to such an extent into the fastening bore that a fastening bolt can be introduced into the bore without obstruction.

The detent means can comprise projections, which are formed at inside flanks of one shell member and extend transversely to a direction of interengagement of the shell members, and corresponding grooves arranged at the outside flanks of the other shell member, the projections and grooves having a substantially semicircular cross-section and snapping into one another on interengagement of the shell members. They can, however, comprise wedges, which are arranged at the inside flanks of the one shell member to extend transversely to the interengagement direction and which detent in corresponding recesses in the outside flanks of the other shell member, the wedges and recesses converging to a point in the interengagement direction.

Advantageously, guide grooves are provided in fastening flanges of one of the shell members and continue into the grooves of the side flanks of that shell member, while fastening flanges of the other shell member are provided with corresponding rails fitting into the grooves, the grooves and rails at one side of the bearing chamber preferably being wider than at the other side.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Fig. 1 is a front elevation of a pedestal bearing housing means according to a first embodiment of the invention, the housing means being shown in assembled form and enclosing a pivot bearing and shaft, Fig. 2 is a partially sectioned front elevation of the housing means of Fig. 1 before assembly, the pivot bearing to be enclosed during assembly being indicated in dashed lines, Fig. 3 is a plan view of the lower shell member of the bearing housing means of Fig 1, Fig. 4 is an inverted plan view of the upper shell member of the bearing housing means of Fig. 1, Fig. 5 is a partly sectioned side elevation of the assembled bearing housing means of Fig. 1, Fig. 6 is a partly sectioned front elevation of pedestal bearing housing means according to a second embodiment of the invention, Fig. 7 is a detail, to an enlarged scale, of detent means of the housing means of Fig. 6, Fig. 8 is a partly sectioned front elevation of pedestal bearing housing means according to a third embodiment of the invention, Fig. 9 is a plan view of the lower housing shell member of the bearing housing of Fig. 8, Fig. 10 is an inverted plan view of the upper shell member of the bearing housing of Fig. 8, Fig. 11 is a partly sectioned front elevation of the shell members of the bearing housing means of Fig. 8, the shell members being assembled around a ball or roller bearing and fastened by bolts to a bracket or the like, Fig. 12 is a detail, to an enlarged scale, of the area "A" encircled by dashed lines in Fig. 11, Fig. 13 is a partly sectioned front elevation of a pedestal bearing means according to a fourth embodiment of the invention, Fig. 14 is a plan view of the lower shell member of the bearing housing means of Fig. 13, Fig. 1 5 is a partly sectioned front elevation of a pedestal bearing housing means modified in relation to that of Figs. 13 and 14, and Fig. 1 6 is a detail of Fig. 1 5 (indicated in dashed lines) but showing the shell members of the bearing housing means assembled together.

Referring now to the drawings, there is shown in Figs. 1 and 2 a pedestal bearing housing for a pivot bearing, the housing being manufactured by injection moulding from a thermo-setting plastics material, for example polymethylenoxide. It is composed of two interengaging housing half shells 1 and 2, wherein respective plug-in rails 4 and 5 are formed on the upper shell 1 at each side of a bearing chamber 3 and corresponding grooveshaped recesses 6 and 7 receiving the associated rails are formed on the lower shell 2 at each side of the bearing chamber 3. Arranged as continuations of the rails 4 and 5 at the undersides of fastening flanges 8 and 9 of the upper shell 1 are guide rails 10 and 11 of equal width.The rails 10 and 11 engage into corresponding guide grooves 12 and 13 at the upper sides of fastening flanges 14 and 1 5 of the lower shell 1 and ensure an accurate seating of the shells. To prevent the shells 1 and 2 from being plugged together turned through 1 800, the width of the rail 4, recess 6, rail 10 and groove 12 at one side of the bearing chamber 3 is narrower than that of the same elements 5, 7, 11 and 13 at the other bearing chamber side (cf. Figs. 3 and 4).

The rails 4 and 5 on the upper shell 1 are provided at their surfaces facing the bearing chamber 3 with projections 16, which extend transversely to the rails and which, on plugging together of the shells 1 and 2, snap into corresponding grooves 1 7 in the bottom surface -- facing the bearing chamber 3 - of the recesses 6 and 7 of the lower shell 1 and thereby firmly interconnect the two shells 1 and 2.

A prerequisite for this closure is that on plugging together of the shells the bow-shaped upper shell 1 springs out to a sufficient extent yet is of such a spring force that the connection is virtually unbreakable. For this purpose, it is expedient not to let the separating plane TE between the shells coincide, as is otherwise usual, with the horizontal plane extending through the transverse axis of the bearing, but to arrange it to extend vertically downwards at both sides of the bearing chamber 3 as far as the support surface of the two shells 1 and 2 on each other. From there, the separating plane again extends horizontally at both sides (cf. Fig. 1).

The bow structure of the upper shell 1 has relatively long bow limbs, whereby the predetermination of the spring tension required for the plugging together of the shell 1 and 2 is made possible.

Before the shell 1 is plugged onto the shell 2, a bearing 1 8 (ball or roller bearing) is laid into the bearing chamber region so that after plugging together of the shells, the bearing 1 8 is firmly enclosed in the bearing chamber 3. As illustrated in Figs. 3 and 4, the bearing chamber walls of the upper and lower shells 1 and 2 can be provided, in accordance with the teaching of DE OS 28 00 648, with annular grooves 19, the planes of which extend transversely to the longitudinal axis of the bearing chamber. The narrow annular protrusions which arise between the grooves 1 9 yield, during the pressing together of the shells 1 and 2, wherever the circumference of the outer bearing ring is greater than the related diameter of the bearing chamber.In this manner, any production inaccuracies in the spherical surfaces are compensated for. However, as Figs.

9, 10 and 14 show, the bearing chambers can equally well have smooth spherical inside surfaces.

As illustrated in Fig. 5, after fastening of the bearing housing composed of the assembled shells 1 and 2 on a bracket 20 or the like (cf. Fig.

11) a journalled shaft 21 can be aligned in correspondence with the alignment between two successive bearing housings and, for example, form an acute angle with the bearing chamber axis LKA. In this case, the grooves 1 9 of the bearing chamber walls are very useful in that they make it possible for the outer bearing ring to adapt itself accurately to the chamber wall even in the inclined setting. A lubricant track 23 is formed at the upper part of the bearing chamber 4 in order to conduct to the bearing 1 8 grease introduced through a lubricant nipple 22.

The embodiment of Figs. 1 to 5 shows projections 16 and corresponding grooves 17, which extend transversely to the rails 4 and 5 or to the recesses 6 and 7, as snap-in elements. As illustrated in the figures, these projections and grooves have a substantially semicircular crosssection. This arrangement makes a problem-free snapping-in possible. With a correctly dimensioned spring tension of the bow-shaped shell 1, the shape-locking, i.e. mechanical, and force-locking, i.e. pressurable, connection of the shells 1 and 2 achieved by the snap-in effect is so firm that the shells can only be subsequently separated through destruction.

In Figs. 6 and 7 there is shown an embodiment with a different structuring of the snap-in elements, which is equally effective but which even with higher spring forces enables plugging together of the shells 1 and 2 without excessive force being required, for example, by hand without the use of tools. In this case, snap-in elements 24 at the rails 4 and 5 have a wedge-shaped crosssection with the wedge pointing downwardly.

Grooves 25 provided at the bottoms of the recesses 6 and 7 have a corresponding wedgeshaped cross-section. On pressing of the shells 1 and 2 together, each wedge 24 slides into the associated groove 25 until the wedge spine snaps in. With sufficient spring tension of the bowshaped shell 1 , the resulting connection is mechanically unbreakable.

In the case of bearing housings for heavy ball bearings, in spite of the prolongation of the bow limbs of the upper shell it may not always be possible to provide the degree of resilience required for the plugging together. If springing out of the bow is too hard and the plugging together has to take place under too great a pressure, there is a risk that the snap-in projections will be sheared off.

For such heavy bearing housings, therefore, the rails 4 and 5 may be arranged to be resiliently deflectable, as shown in Figs. 8 to 12. The resilient rails 4 and 5 are dimensioned to be of such thinness that they can spring out, i.e. away from the bearing chamber 3, during plugging together of the shells 1 and 2. To make this spring-out possible, a respective box-shaped deflection space 26 and 27 is formed beside each rail 4 and 5 and cuts through a respective one of two fastening bores 28 and 29 in the upper shell 1. During plugging together of the shells 1 and 2, the rails 4 and 5 spring out into the spaces 26 and 27 until the projections 16 snap into the grooves 17. The rails then spring back into their rest position.

When the assembled bearing housing with associated ball or roller bearing 1 8 is fastened by means of threaded bolts 30 to the bracket 20 or the like, the bolts 30 fill the spaces 26 and 27 and bear against the rails 4 and 5, which are thereby held in their snap-in position.

To render this blocking effective, the tolerance of bolt and fastening bore must be smaller than the cross-section of the snap-in projection. This can be secured by providing each rail 4 and 5 at its lower end with a reinforcement 31 which, even in the normal position, projects by about half the tolerance into the fastening bore 28 or 29.

Provided in the shell 2 adjacent each reinforcement 31 in the plug-in position thereof is a respective recess 32. If the bearing housing is to be disassembled, after withdrawal of the bolts 30 a screwdriver or the like can be inserted into the recess 32 to lever the rails 4 and 5 out of their closing position. It is thus possible to take the bearing housing apart at any time. The bearing housing remains an indivisible unit only as long as it is fastened at its point of installation.

In the embodiment shown in Figs. 13 and 14, the bottom walls 33 and 34 of the recesses 6 and 7 spring inwardly in the direction of the bearing chamber 3 when the rigid rails 4 and 5 of the upper shell 1 are plugged onto the lower shell 2.

The springing-in of the bottom walls 33 and 34 is made possible by provision of a respective deep, box-shaped deflection recess 35 or 36 behind each bottom wall and by separation of the flanks of the walls 33 and 34 by separating cuts 37 from the side walls of the recesses 6 and 7. The bottom walls 33 and 34 can now resiliently bend out against the spring force when the rigid rails 4 and 5 encompass the bottom walls. The snap-in projections 1 6 in this case are arranged at the bottoms of the recesses 6 and 7 in order not to unnecessarily weaken the resilient bottom walls 33 and 34. The snap-in grooves 17 are correspondingly formed in the rigid rails 4 and 5.

Shown in Figs. 15 and 16 are locking projections 38 and 39, which are formed at the underside of the upper shell 1 and correspond to the recesses 35 and 36 in the lower shell 2. For the purpose of the reception of the projections 38 and 39 during plugging together of the shells, the edges of the recesses 35 and 36 are chamfered or countersunk at 40 and 41. At the end of the plugging together operation, i.e. at the instant of the snapping-in of the projections 1 6 and 17, the projections 38 and 39 enter the recesses formed by the countersinkings and prevent return of the resilient bottom walls 33 and 34. The connection provided by the snap-in projections 16 and 17 is thus rendered unbreakable.

Claims

1. Pedestal bearing housing means of plastics material comprising a base shell member and a cover shell member which are interengageable to form a housing for a pivot bearing and which are provided with laterally disposed complementary detent means adapted to so resiliently snap into interengagement on said interengagement of the shell members as to pressurably and mechanically lock the shell members together.

2. Bearing housing means as claimed in claim 1, wherein the cover shell member comprises two limbs arranged to resiliently encompass lateral regions of the base shell member when the shell members are interengaged, the complementary detent means being provided by projections disposed on inwardly facing surface portions of the limbs and corresponding depressions in outwardly facing surface portions of said lateral regions.

3. Bearing housing means as claimed in either claim 1 or claim 2, wherein the shell members are provided with co-operable fastening flanges and are adapted to interengage in a first zone of contact lying in a plane which extends parallel to a base support surface of the base shell member and contains the axis of a bearing chamber defined by the shell members when interengaged, second zones of contact arranged to extend one on each side of such chamber from the first contact zone towards the base support surface, and third zones of contact extending from the second contact zones in the plane of contact surfaces of the flanges.

4. Bearing housing means as claimed in any one of the preceding claims, wherein the cover shell member is provided with guide rails arranged to extend one on each side of a bearing chamber defined by the shell members when interengaged and the base cover member is provided with corresponding grooves arranged to receive the rails during interengagement of the shell members.

5. Bearing housing means as claimed in claim 4, wherein the complementary detent means are provided on the rails and in the grooves and the base shell member is provided in the region of each groove with a recess which is of substantially the same length and width as the groove and which is so arranged as to permit the detent means in the grooves to be resiliently deflectable.

6. Bearing housing means as claimed in claim 5, wherein each of the recesses is provided with a countersunk end portion and the cover shell member is provided with substantially conical projections engageable in said end portions of the recesses on said interengagement of the shell members.

7. Bearing housing means as claimed in claim 4, wherein the complementary detent means are provided on the rails and in the grooves and the cover shell member is provided in the region of each rail with a recess which is of substantially the same length and width as the respective rail and which is so arranged as to permit the rail to be resiliently deflectable.

8. Bearing housing means as claimed in claim 7, wherein the cover shell member is provided with bores for fastening elements, the bores being intersected by the recesses.

9. Bearing housing means as claimed in claim 4, wherein the cover shell member is provided in the region of each rail with a bore for a fastening element of given diameter and each of the rails is provided at a free end thereof with an enlarged portion which so projects into the bore at one side thereof as to be disposed at a spacing from the diametrically opposite side of the bore by an amount substantially equal to said diameter.

10. Bearing housing means as claimed in any one of the preceding claims1 wherein the complementary detent means are provided by projections of substantially semi-circular crosssection so arranged on inwardly facing lateral surface portions of one of the shell members as to extend perpendicularly to a direction of relative movement of the shell members to effect said interengagement and by correspondingly shaped depressions arranged in outwardly facing lateral surface portions of the other shell member.

11. Bearing housing means as claimed in any one of claims 1 to 9, wherein the complementary detent means are provided by wedge-shaped projections so arranged on inwardly facing lateral surface portions of one of the shell members as to taper inwardly in the direction of movement of that shell member relative to the other shell member for said interengagement of the shell members and by correspondingly shaped depressions arranged in outwardly facing lateral surface portions of the other shell member.

12. Bearing housing means as claimed in claim 4, wherein the shell members are provided with fastening flanges, the flanges of the cover shell member being provided with extensions of the guide rails and the flanges of the base shell member with corresponding extensions of the grooves to receive the rail extensions during interengagement of the shell members.

1 3. Bearing housing means as claimed in claim 12, wherein one of the rails and the associated groove are wider than the other rail and groove.

14. Pedestal bearing housing means substantially as hereinbefore described with reference to Figs. 1 to 5, Figs. 6 and 7, Figs. 8 to 12, Figs. 13 and 14 or Figs. 1 5 and 16 of the accompanying drawings.

1 5. A pedestal bearing housing comprising interlocked shell members of bearing housing means as claimed in any one of the preceding claims.

1 6. A pedestal bearing assembly comprising a housing as claimed in claim 1 5 and a pivot bearing retained in the housing.