Background of the invention Flexible or elastic bellows-type covers usually of accordion- like construction, such as axle boots for universal joints or for drive shafts, must be carefully sealed to protect the lu- bricant. Such bellows-type covers have been used extensively in the automotive industry, for example to protect joints at a drive shaft. They are normally fastened to the axle stub shafts by means of hose clamps or shrinkable compression rings. A need exists at present on the part of manufacturers of universal joint shafts or drive shafts for bellows-type covers in which clamping members in the form of"Oetiker"hose clamps or "Oetiker"shrinkable compression rings are already integrated into the bellows-type covers. In other words, the manufacturers desire a product in which the clamping members are already in- tegrated at or in the bellows-type covers which favours the automatic assembly of the universal joint or drive shafts in that the bellows-type covers provided with integrated clamping members are available as pre-assembled parts so as to avoid the need for mounting the clamping members on the bellows-type cov- ers only at the final assembly as is often the case today.

Summary of the invention Two possibilities exist, in principle, for a clamping member to be integrated into the bellows-type cover which consist of (1) the clamping member vulcanised into the bellows-type cover or (2) a self-holding arrangement for a clamping member adapted to be mounted on the bellows-type cover. Of these two possibili- ties, the first solution involving the clamping member vulcan- ised into the bellows-type cover can be disregarded because such an arrangement is practically not feasible with the usual hose clamps presently used as clamping members as also with compression rings used as clamping members. For example, a stepless hose clamp of the type disclosed in the U. S. Patent 4,299,012, which has been used extensively with axle boots in the automotive industry, if vulcanised into the bellows-type cover, would present great difficulty of being tightened by de- forming the"Oetiker ear. The vulcanised-in solution is also unacceptable because of substantial increase in costs. A shrinkable compression ring, vulcanised into the bellows-type cover can no longer be shrunk by means of the presently avail- able tools because these tools are designed to engage during the shrinking operation with the external surface of the com- pression ring having a predetermined diameter in a form-locking manner in order to reduce the compression ring in its diametric dimension by the application of radial forces. The layer of rubber or plastic material applied over the vulcanised-in shrinkable compression ring formed by the vulcanising operation prevents a form-locking connection between the compression ring and the compression tool. Equally inappropriate are arguments that vulcanising-in of the clamping members into the bellows- . type covers provides a corrosion protection of the integrated

hose clamps or compression rings because these problems can be readily avoided in the present invention by the use of appro- priate materials for the clamping devices, such as stainless steel or aluminum. Furthermore, a vulcanising-in of the clamp- ing members precludes any visual control provided at the clamp- ing member in the installed condition insofar as correct posi- tioning and seating of the clamping member and proper tighten- ing of the clamping member are concerned. Visual inspection of indications relating to manufacturer of the clamping members and/or installation dates would also become impossible. Up to the present, hose clamps used with drive or universal joint shafts have served extensively as information carriers in that dates such as assembly dates or other relevant dates of inter- est to the manufacturer were integrated into the clamping de- vices, for example, by stamping. Such visual inspections and controls are possible only as long as the clamping members are freely exposed which is not the case with a vulcanised-in solu- tion.

Therefore, as a consequence the EP 0 809 034 proposes a bel- lows-type cover with integrated clamping member, which is adapted to be securely integrated to form a preassembled unit.

A groove-shaped recess near one end of the bellows-type cover adapted to receive the clamping member has a two-tier position- ing arrangement with a radially inward, circumferentially ex- tending bottom surface for engagement by the clamping member when fully tightened and with a temporary bottom for the clamp- ing member to provide a releasable self-retaining support for the closed, but not yet fully tightened clamping member at a radial distance between the bottom surface and the radially outer limit of the recess. Due to new production techniques for

such kind of bellows-type cover members, such as blow injection or blow extrusion, it became very difficult or even impossible to produce the proposed bellows-type covers with integrated clamping members according to the EP 0 809 034.

Therefore, it is an object of the present invention to provide a bellows-type cover member with an integrated clamping member, similar to the one proposed in the EP 0 809 034 with the dif- ference, that the bellows-type cover can easily be produced us- ing new plastics processing techniques.

According to one embodiment of this invention, the pre- assembled unit consists of a bellows-type cover of rubber or plastic material and of an"Oetiker"shrinkable compression ring or hose clamp of metal, both readily mass-producible items, in which the clamping member, as customary to date, is installed between first and second retaining means protruding from the external diameter for receiving the clamping member at both ends of the bellows-type cover, i. e., in the small as also in the large outer diameter area of the bellows-type cover. To date, often groove-shaped recesses formed by fully around ex- tending retaining means serve exclusively for the correct guid- ance of the clamping member in the fully installed condition but are unable to provide any self-retaining function for a pre-assembled clamping member such as a compression ring inte- grated into the bellows-type cover.

As mentioned above in that respect the EP 0 809 034 proposes circumferentially extending bottom surfaces, which are an inte- gral part of the around extending retaining means. In principle this circumferentially extending bottom surface, which provides . a releasable self-retaining support, makes it possible to ar-

range a clamping member to form a preassembled unit to overcome the disadvantages of the still often used bellows-type cover members as mentioned above. The disadvantage of the arrangement according to the EP 0 809 034 is that it is practically impos- sible to produce the bellows-type cover using modern plastics processing techniques, such as blow moulding or blow extrusion.

The difference of the inventive embodiment is that a further means is proposed to provide a self-retaining support for the clamping member in a preassembled position at a distance of the bottom surface of the bellows-type cover member between the first and the second retaining means, which is not an integral part of the mentioned first and second retaining means, but which is arranged at a distance from the first retaining means as well as from the second retaining means.

According to a preferred embodiment of this invention, the bel- lows-type cover at the section of the retaining means for re- ceiving the clamping member is of two-tier construction in that it is now provided with at least one, preferably with several, detent elements along the circumference thereof between the re- taining means which position and hold the compression ring in a self-retaining manner, once placed between the retaining means prior to tightening or shrinking of the clamping member. The clamping member, such as a compression ring, can now be removed again from the bellows-type cover only with the use of large forces. As a result thereof, the clamping member such as a com- pression ring which is now automatically retained after being mounted on the bellows-type cover between the retaining means, now forms an integrated unit with the bellows-type cover for further processing the integrated unit of bellows-type cover . and clamping member. The use of detent elements offers the ad-

vantage of providing a two-tier structure for accommodating the clamping member in which the radially outer position securely but only temporarily holds the clamping member as a part inte- grated into the bellows-type cover yet permits complete, reli- able tightening of the clamping member by releasing the tempo- rary radially outer position in the presence of predetermined tightening forces. The term"clamping member is used in this application to describe both conventional clamps such as "Oetiker"stepless clamps as presently used with bellows-type covers as also shrinkable compression rings such as"Oetiker" puzzle lock compression rings as disclosed in U. S. Patents 5,001,816 and 5,185,908, or any other kind of so-called press rings, clamping rings or shrinkable compression rings.

Brief description to the drawings These and other objects, features and advantages of this inven- tion will become more apparent from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, embodiments in accor- dance with the present invention, and wherein: Fig. 1 is a schematic side-view of a bellows-type cover in accordance with the present invention; Fig. 2 is a partial axial cross-sectional view through an end part of a bellows-type cover in accordance with Fig. 1 (along line I-I); Fig. 3 is an enlarged partial axial cross-sectional view through one end of the bellows-type cover of Fig. 2, showing a clamping member in the form of a compres- sion ring in the integrated, pre-assembled condition;

Fig. 4 is an enlarged partial axial cross-sectional view, similar to Fig. 3, showing the clamping member in the fully installed condition after the shrinking opera- tion; Fig. 5 is a perspective view of a bellows-type cover, simi- lar to the one shown in Fig. 1, including a temporar- ily held clamping member before tightening; Fig. 6 the bellows-type cover with clamping member according to Fig. 5 in a view from the front side of the bel- lows-type cover; Fig. 7 a perspective view of the end part of a bellows-type cover, similar to the one shown in Fig. 1, with a different design of the one end, and Fig. 8 the end of the bellows-type cover according to Fig.

7, holding a temporary clamping member before tight- ening or shrinking of the clamping member.

Detailed description of the drawings Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, reference numeral 10 generally designates a bellows-type cover of elastic material such as rubber or plastic material which may be of any known construction. The two-tier arrangement pro- vided, for example, at the large end of the bellows-type cover 10 is generally designated by reference numeral 11 which is provided with e. g. four circumferentially arranged first outer and second inner retaining projections, designated by reference numerals 20 and 22 which provide the positioning of the clamp- ing member. The projections 20 and 22 are provided with side

walls 23 and 24 and are spaced in the axial direction from one another at a distance slightly greater than the width of the clamping member generally designated by reference numeral 40.

The radial depth of the projections is thereby slightly larger than the thickness of the clamping member 40. The radially outer retaining projections 20 of the structure are preferably formed by blown or bent out portions of the end portion 11 forming corresponding recesses 25. The radially inner retaining means 22 of the structure are formed by steps or projections within the outer side wall of the first bellows 31 of the bel- lows-type cover 10, which might be obtained by blow moulding or blow extrusion, using a correspondingly shaped tool. Within the upper surface 27 of the recess 26 extending between the two projections 20 and 22 further detent members or projections 28 which are circumferentially arranged are protuberated or bent out from the surface 27, forming corresponding recesses 29 on the backside of the basis 27. The detent-like members or pro- jections 28 are integral with the basis of the larger end 11 of the bellows-type cover 10 and are therefore made of the same elastic material which permits yielding thereof. In addition, preferably on both sides of the detent-like members or projec- tions 25 small or narrow grooves 33 are arranged, which are preferably extending circumferentially around the whole surface 27. In addition, on the backside of the basis 27 in the section of the detent-like member 1 or 2 projections 35 are arranged, which are extending circumferentially along the backside of the basis 27 and which are provided to engage in corresponding re- cesses arranged on the metal surface of the shaft, on which the bellows-type cover member is to be secured.

As shown in Fig. 1, the detent-like members, such as three, four or more, are distributed uniformly over the circumference of the basis 27 and retain the clamping member 40 such as an "Oetiker"puzzle-lock compression ring in the pre-assembled condition in which the clamping member 40 is securely held in- tegrated with the bellows-type cover 10 because of the self- retaining function of the upper part of the side walls 23 and 24 of the projections 20 and 22 disposed radially outwardly of the detent-like members 28. Upon application of tightening forces, the detent-like members 28 are able to yield to permit the clamping member 40 to enter the radially inward part of the groove-shaped recess 26 extending between the projections 20 and 22 in which they are then firmly held in position on the basis 27 of the groove-shaped recess 26 as a result of the tightening, respectively, shrinking of the diametric dimension thereof.

As mentioned above, the use of groove-shaped recesses in the external surfaces of the ends of bellows-type covers are known.

However, up to now, they merely served the purpose of guiding the clamping member in the fully installed condition. The prob- lem of providing a two-tier arrangement in which a self-holding feature is also attained in the radially outer position would not be attainable without the use of the detent-like members 28, because even a deeper recess between the retaining projec- tions 20 and 22 would not safely provide the self-retaining ac- tion necessary to constitute the clamping member as a part in- tegrated into the bellows-type cover because of the likelihood of the clamping member becoming detached again from the bel- lows-type cover when one side of the clamping member enters the . groove-shaped recess between the retaining projections 20 and

22 to abut at the basis of the recess, in which case the oppo- site side would be able to slip out over the edge of the outer projection 22. Detent-like members in the form of elastic out- ward extending projections 28 which provide a temporary radi- ally outer position of the two-tier arrangement with a com- pletely safe retaining function to achieve the required inte- gration are therefore necessary to assure an assembly of a bel- lows-type cover with integrated clamping member. The external surface 12 of the. outer end of the outer retaining projections 20 is thereby inclined to form a rectilinearly obliquely up- wardly extending flank to assist in centering and mounting the clamping ring in the recess between the retaining projections 20 and 22 of the self-retaining arrangement.

The bellows-type cover 10 is made of rubber, a thermoplastic or another elastomeric polymer material, such as polyester or polyamid elastomeric material, as e. g. of Hytrel, and is to be fastened over a metallic axle stub by means of a shrinkable compression ring such as an"Oetiker"puzzle-type compression ring as disclosed in the aforementioned U. S. patents.

Fig. 5 now shows again in perspective view the larger end por- tion of the bellows-type cover with the temporarily held clamp- ing member 40 before shrinkage. In the perspective view of Fig.

5, two outer retaining means or projections 20 are visible as well as two of the inner retaining means or steps 22. Within the open end of the end portion on the other hand two recesses 25 are visible, which form the punched out retaining projec- tions 20, which are on the non-visible surface of the large end portion 11 of the bellows-type cover 10. In addition, the de- tent members 28 are not visible in the arrangement according to Fig. 5, as they are covered by the temporarily arranged clamp-

ing member 40. On the other hand, again within the open end of the large end portion 11, a corresponding recess 29 is visible, which has been formed by punching out the detent-like projec- tions 28, to hold the clamping member 40 in the pre-assembled condition.

In Fig. 6 the end portion 11 of Fig. 5 is seen from the front side to show-the four outer retaining projections 20, which at least partially cover the clamping ring 40 in the visible di- rection. The example shown in Figs. 5 and 6 shows the arrange- ment of four outer retaining projections 20 as well as four in- ner retaining steps 22 as an example for the better understand- ing of this invention. Of course it is possible to arrange also three or five, six or more retaining means. It is even possible to arrange outer and inner retaining means, which are formed by a full ring projection. As according to the invention, prefera- bly the retaining means are blown or bent out of the end por- tion of the bellows-type member, it is finally a question of manufacturing and of requirements, how many retaining projec- tions are arranged. The same has to me mentioned in relation to the detent-like member 28, of which also only two, three or more projection members can be arranged as well as a fully out- ward extending ring, which again is protuberated, blown or bent out of the basis of the end portion, extending between the two retaining means.

In Fig. 7 a different design of an end portion of a bellows- type member is shown, as e. g. the small end of the bellows-type member, as shown e. g. in Fig. 1. Again, the outer and inner re- taining projections 20 and 22 are visible, which again are preferably blown or bent out of the smaller end portion. Be- tween the two retaining projections 20 and 22, two ring-like

detent members 28 are arranged in the form of outward extending projections. Within the open end of the small end 13 of the bellows-type cover 10 at least partially the corresponding a ring forming recess 29 is shown to demonstrate that again the detent-like projections 28 are blow-moulded or blow-extruded out of the end portion 13.

Fig. 8 finally shows the end portion of Fig. 7 with the clamp- ing ring 40 arranged before shrinkage.

While only a few embodiments have been shown and described in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art.

The two-tier arrangement may be used with any type of bellows made from any appropriate known elastic material whereby the detent members are designed to provide the required elasticity considering the material used for the bellows-type cover and the need for yieldingness to permit a release of the temporary radially outer position of the integrated clamping member. Fur- thermore, the detent members may be arranged between two re- taining projections, but of course may be arranged at any place around the surface of the end portion of the bellows which is determined for the engagement of the clamp-like member. In other words, in axial direction of the bellows the inner re- taining means, the detent-like member and the outer retaining means do not have to be within one line. The inner retaining means, the detent-like member as well as the outer retaining means may be arranged in staggered relationship, so that one first retaining means or detent member on one side is followed in a staggered manner in the circumferential direction by the next second retaining means or detent member on the other side,

and so on. Additionally, the flank surface 12 needs not to be rectilinear, but may also have a curved configuration of any appropriate shape.

As a consequence therefore the present invention is not at all limited to the details shown and described herein, but is in- tended to cover all such changes and modifications as are en- compassed by-the scope of the appended claims.