Clamp structure with improved spring action

Abstract: An auxiliary spring structure (10) for use with open clamps in which the auxiliary spring member is contained within a cage (20) formed by the outer band portion whereby the free leg portions of the auxiliary spring member extend through slot-like openings in the cage to engage the latter from the outside so as to resist elastically forces seeking to enlarge the circumferential dimensions of the clamp. In another embodiment, the auxiliary spring structure (10) is formed by one or preferably several inter-engaged leaf springs (111,112) which are connected between the end area of the outer band portion and the clamping band near the beginning of the inner band portion. Any gaps resulting in the auxiliary spring structure are thereby covered by the full band width of the inner band portion. The auxiliary spring structure of this invention can be used with one-ear clamps, earless clamps and screw-type clamps.

Description: The invention is concerned with an open clamp including the features as outlined in the preamble of claim 1. Both closed clamps made from tubular stock as well as open clamps provided with mechanical interconnecting means, which utilized plastically deformable so-called "Oetiker" ears have proved immensely successful over more than three decades. U.S. Patents 2 614 304, 2 847 742, 3 082 498 and 3 402 436 are representative of some of the types of clamps which have been sold worldwide in large quantities. With the advent of new plastic, relatively harder hose materials, as used, for example, with axle boots, the need for an internal clamping surface devoid of any gaps, discontinuities or steps became imperative to assure complete tightening of the axle boot. Additionally, the mechanical connection used heretofore with open clamps and consisting of one or more sustantially U-shaped members bent out of the material about an axis transverse to the longitudinal direction of the clamping band, as disclosed, for instance, in U.S. Patent 3 475 793, imposed limitations on the strength to resist opening forces, i.e., of holding together the overlapping band ends of open clamps, particularly when higher tightening forces are used. U.S. Patents 4 299 012, 4 315 348 and 4 622 720 disclose solutions which have also proved immensely successful in practice. Furthermore, the relatively narrow canoe-shaped reinforcing groove as proposed in U.S. Patent 3 475 793 has been vastly improved in the bridging portion of a so-called "Oetiker" ear by a relatively shallow depression of approximately rectangular configuration in plan view with the sides thereof extending at least over half the length and width of the bridging portion. Details of the improved reinforcing depression are disclosed in British Patent 2 160 577. One of the reasons for the immense commercial success of applicant's various clamp products is attributable to the particular features obtainable with the plastically deformable, so-called "Oetiker" ear which, when plastically deformed to tighten the clamp about the object to be fastened thereby, provided an automatic spring action to compensate for changes in temperature and/or pressure. This compensating action, however, is limited by the yield strength of the clamping band material of which the plastically deformable ear is also made. Once the elastic limit of the clamping band material is reached, the automatic spring action of the plastically deformed "Oetiker" ear is jeopardized. In other words, the maximum spring path allowed by an "Oetiker" ear, i.e., the maximum increase in the circumferential dimension of the clamp, is limited by the elastic limit of the clamping band material. If this elastic limit is exceeded, for example, as a result of temperature increases in the cooling medium carried by a radiator hose, there exists a serious leakage problem when the cooling medium cools down again because the clamp will not elastically return to its original dimensions with the same clamping force. These problems have been confronted by clamp structures in which the plastically deformed "Oetiker" ear was formed in a separate connecting member which could be made of a material having greater yield strength than the material of the clamping band. U.S. Patent 2 847 742 is representative of this approach. However, both from a cost point of view as well as from an installation point of view, it is desirable to make the plastically deformable ear integral with the clamping band. U.S. Patent 3 475 793 proposed the use of tensional spring elements formed in the clamping band itself which was then made from appropriate spring steel material as contrasted to soft steel. If in addition to one or more tensional spring elements, also a plastically deformable "Oetiker" ear was desired in such open clamp, it became necessary to submit the clamping band to additional heat treatment in order to provide a plastically deformable material within the area of the "Oetiker" ear. As hermetically sealed cooling systems in the automotive industry permit ever-increasing temperatures of the cooling fluid and as the new hose materials exhibit greater likelihood to change the external configuration within the area of the clamping band where grooves or indentations are formed, there exists a need for increasing the maximum spring path, i.e. provide greater elastic automatic compensation to maintain tightness of the hose connection. The EP 0 280 598 already addressed this problem to establish an "elasticity reserve" by the use of a loop formed in the clamping band which is externally surrounded by a spring sleeve. To cover the gap underneath the loop and to limit the elastic deflection of the loop and its external cylindrical spring sleeve, a separate part is used which is installed so as to extend underneath the clamping band and over the spring sleeve. This arrangement requires a number of parts which increases the cost of manufacture and assembly and additionally requires a separate part to cover the gap underneath the loop. Furthermore, steps are formed at the point of mechanical connection between the inner and outer band portions. The present invention has as object to provide an auxiliary spring structure which is simple to manufacture, easy to install and capable of being adapted to the exigencies of a given situation, and which increases the maximum spring path possible by the clamp and at the same time assures a completely satisfactory internal clamping surface devoid of any gaps, discontinuities or steps by extremely simple means. This object is solved by the features indicated in claim 1. Further advantages are described in the subclaims. According to the invention, the auxiliary spring member may be constituted by a spring member made from appropriately selected spring material or may consist of a number of convexly shaped leaf springs to permit adaptation to the needs of a given situation. According to the invention, any gap underneath the auxiliary spring member is covered by the full band width of the inner band portion. According to still another feature of the invention the overlapping band portions are so constructed and arranged that an internal clamping surface is assured devoid of any gaps, discontinuities or steps. According to a particular embodiment of the invention, friction is far-reachingly eliminated during sliding movement of the inner band portion relative to the outer band portion. This may be achieved by spaced ribs along the outer surface of the inner band portion which extend over a predetermined circumferential distance of the inner band portion. As a result thereof, the friction forces which may occur, for example, during closing of an "Oetiker" ear in a one-ear clamp structure and/or during operation of the auxiliary spring structure, are far-reachingly minimized, thereby substantially improving performance of the clamp. According to still another embodiment of the invention, means may be provided in overlapping inner and outer band portions for limiting the extent of elastic deflection of the auxiliary spring structure. These means can be attained in a simple manner by one or more outwardly extending projections or hooks in the inner band portion adapted to engage in an oversize aperture or apertures in the outer band portion, the dimensions of which limit movement of the projection or hook in the presence of forces seeking to increase the circumferential dimensions of the clamp. The auxiliary spring structure may be formed by one or preferably several convexly shaped leaf spring members which are interconnected between the end area of the outer band portion and a corresponding part of the clamping band where it is about to pass over into the inner band portion. The mechanical connection of the auxiliary spring member may thereby be achieved in a particularly simple manner by outwardly extending hooks in the outer band portion and adjacent clamping band portion forming the inner band portion whereby these hooks point in opposite direction and engage in corresponding apertures in the auxiliary spring member, respectively, in the several leaf spring elements thereof. In this manner, two important advantages are achieved. On the one hand, the ordinary mechanical connection between the outer and inner band portions is now taken over by the auxiliary spring structure which, by the use of appropriately designed hooks in conjunction with appropriately shaped inner ends of the leaf spring members, can be made to withstand considerable tensional forces in the circumferential direction. At the same time, the gap underneath the convexly shaped auxiliary spring member is automatically covered by the full width of the clamping band. Another important advantage of the auxiliary spring structure of the present invention is its universal applicability to different types of open clamps. The auxiliary spring structure in accordance with the present invention may be used, for example, with so-called one-ear clamps, so-called earless clamps and/or so-called screw-type clamps whereby an internal clamping surface devoid of any gaps, discontinuities or steps can be assured by extremely simple means. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein: Figure 1 is a perspective view of a one-ear clamp with an auxiliary spring structure in accordance with the present invention; Figure 2 is a cross-sectional view, taken along line 2-2 of Figure 1; Figure 3 is a partial plan view on the clamp illustrated in Figure 1 within the area of the arrow H; Figure 4 is an elevational view, illustrating the clamp of Figure 1 in the installed condition and under the influence seeking to increase the circumferential dimensions of the clamp; Figure 5 is a partial cross-sectional view in a plane containing the auxiliary spring structure 110 and transverse to the axis of the clamp, illustrating the parts in their condition under the influence of forces seeking to increase the circumferential dimensions of the clamp; Figure 6 is a partial plan view in the direction of arrow H' and showing the parts in the position of maximum stretching of the auxiliary spring structure; Figure 7 is a partial top plan view on the inner band portion provided with reinforcing ribs; Figure 8 is a cross-sectional view, taken along line 8-8 of Figure 7; and Figure 9 is a cross-sectional view, taken along 9-9 of Figure 1. DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawing wherein like reference numerals are used throughout the various views to designate corresponding parts, and more particularly to Figure 1, the auxiliary spring structure generally designated by reference numeral 110 includes a number of convexly shaped leaf spring members 111 and 112 having a width corresponding substantially to the width of the clamping band and being of approximately omega shape. The leaf spring members 111 and 112 have a more or less flat top portion 111b and 112b passing over into convexly shaped side portions 111c and 112c which terminate in spaced end portions 111a and 112a. The spaced inner end portions 111a and 112a of the leaf spring members 111 and 112 are thereby bent so as to point in the direction toward the substantially rectilinear top portions 111b and 112b. The end area of the outer band portion 11a is provided with a substantially S-shaped hook 118 adapted to engage in apertures 111d and 112d (Figure 5) provided in the right inner end portions 111a and 112a of the leaf spring members 111 and 112 while a substantially S-shaped hook 119 in the clamping band 11 where it is just about to pass over into the inner band portion 11b is adapted to engage in corresponding apertures 111d and 112d provided in the left inner end portions 111a and 112a of the leaf spring members 111 and 112. The hooks 118 and 119 which point in opposite direction away from each other in conjunction with the apertures 111d and 112d which are open from the ends of the inner end portions 111a and 112a, thereby take over the mechanical interconnection between the inner and outer band portions 11b and 11a whereby the gap 117 underneath the leaf spring members 111 and 112 is covered by the full band width of the clamping band. The inner and outer band portions 11b and 11a are also provided with means generally designated by reference numeral 120 and reference numeral 130 (Figure 3) for limiting the elastic deformation of the auxiliary spring structure 110. The limiting means 120 and 130 includes a hook 121, respectively, 131 extending outwardly from the inner band portion 11b and adapted to engage in an oversize aperture 122, respectively, 132 provided in the outer band portion 11a so that the oversize apertures 122 and 132 determine the extent of relative movement of the inner and outer band portions 11b and 11a and therewith the extent to which the auxiliary spring structure 110 can be subjected to stretching forces. The auxiliary spring structure is followed in a direction away from the free end of the outer band portion 11a by a plastically deformable so-called "Oetiker" ear generally designated by reference numeral 41 and including generally outwardly extending leg portions 42a and 42b interconnected by a bridging portion 43 which is provided with a reinforcement 44, preferably with a relatively shallow, generally pan-shaped depression of substantially rectangular configuration as viewed in plan view, as more fully described in U.S. Patent 5,282,295. The inner and outer band portions 11b and 11a are thereby mechanically interconnected as described above. In order to achieve an internal clamping surface devoid of any gap, discontinuity or step, the inner band portion 11b is provided with a tongue portion 47 adapted to engage in a centrally located pressed-out channel 48 leaving lateral band portions 11a' and 11a'' on both sides of the pressed-out tongue-receiving channel 48 (Figure 9). The pressed-out tongue-receiving channel 48 thereby commences within the area of a first step-like portion 49, raising the lateral band portions 11a' and 11a" to the height of the channel and terminates within the area of a second step-like portion 45 spaced from the first step-like portion 49 in the direction of the tongue portion 47, i.e., in a direction away from the auxiliary spring structure 10. These means 45, 47, 48 and 49 to provide an internal clamping surface devoid of any gaps, discontinuities or steps are of the type more fully described in applicant's prior U.S. Patent 4,299,012. In order to minimize friction during closing of the ear-like structure 41 and to permit the auxiliary spring structure to operate with a minimum of friction resulting in overlapping band areas, the inner band portion 11b is provided with pressed-out ribs 12 and 13 spaced from each other and located near the outer end areas of the clamping band, as viewed in transverse cross section (Figure 8). These ribs 12 and 13 are thereby so constructed as to minimize friction during relative movements of overlapping band portions by the use of rounded-off tips having a relatively small radius of curvature, determined by the size of the ribs. These ribs 12 and 13 thereby extend within an area of overlap of the inner and outer band portions 11b and 11a as selected by the designer of the clamp, preferably over such a circumferential extent within the area between the mechanical connection of the inner and outer band portions to the area near the point where the tongue portion commences so that in the installed condition of the clamp, the gap underneath the ear-like structure 41, like the auxiliary spring structure 110, can also be covered by the full band width of the inner band portion 11b. A clamp with a plastically deformable ear 41 as well as with an auxiliary spring structure 110 increasing the maximum spring path is thus obtained in which the inner clamping surface is devoid of any gap, discontinuity or step. This clamp structure can be made in a relatively simple, cost-efficient manner by stamping out the flat clamping band, and mounting the auxiliary spring 110, whereupon the one-ear clamp is ready for installation and plastic deformation of its ear-like structure during tightening of the clamp over the object to be fastened thereby. The clamp illustrated in Figures 1 through 9 requires only two separate parts which can already be preassembled at the place of manufacture so as to be ready for use in installing the clamp over the object to be fastened thereby and then tightening the clamp. An important feature of the auxiliary spring illustrated in Figures 1-9 is the fact that the gap formed underneath the auxiliary spring structure 110 as well as underneath the ear 41 can be bridged by the full band width of the inner band portion 11b. It is understood that the auxiliary spring structure in accordance with the present invention may be used with an open clamp having more than one so-called "Oetiker" ear as also with any other type of so-called "STEPLESS" clamps.

Claims: An open clamp which includes a clamping band (11) defining an internal clamping surface devoid of any gaps which includes overlapping band portions (11a,11b) and an arrangement (41) for tightening the clamp about an object to be fastened thereby, comprising an auxiliary spring structure (110) operable to confer a spring path of the clamp which, separate from the clamping band and from the tightening arrangement and circumferentially spaced from said arrangement (41) for tightening the clamp, is interconnected between overlapping band portions and provides predetermined elastic retightening forces in the presence of forces increasing the diametric dimension of the clamp, said auxiliary spring structure (110) being of at least part convexly shaped configuration with inwardly disposed end portions (111a,112a) directed towards one another and forming a gap under the end portions (111a,112a) of the auxiliary spring structure with the gap increasing with increases in the diametric dimension of the clamp, the gap being bridged by a full band width part (11b) of the clamping band itself, and the mechanical interconnection between the inner and outer band portions (11b,11a) being formed by the interconnection (118,119) of the auxiliary spring structure (120) with the end area of the outer clamping band portion (11a) and with said part (11b) of the clamping band. An open clamp structure according to claim 1, wherein the mechanical interconnection includes outwardly extending hooks (118,119) in the corresponding parts of the overlapping band portions (11a,11b) operable to engage with the inwardly disposed end portions (111a,112a). An open clamp according to claim 1 or 2, characterized in that said arrangement (41) for tightening includes a plastically deformable ear-like means (41) including two generally outwardly extending leg portions (42a,42b) connected by a bridging portion (43), and in that the ear-like means (41) is spaced from said auxiliary spring structure (110) away from the free end of the outer band portion (11a) with the gap underneath the ear-like means covered also by the full band width of the inner band portion (11b). An open clamp according to claim 3, characterized in that the bridging portion (43) is provided with reinforcing means (44) formed by a shallow depression of approximately rectangular shape as viewed in plan view, whose sides extend over at least half the length and width of the length and width of said bridging portion. An open clamp according to any one of claims 1-4, characterized in that overlapping inner and outer band portions (11b, 11a) include an additional arrangement (47, 48, 49, 45) to provide an internal clamping surface devoid over its entire circumference of any gap, step or discontinuity. An open clamp according to claim 5, characterized in that the additional arrangement includes a tongue-like portion (47) at the inner band portion (11b), and tongue-receiving means (48) in the overlapping outer band portion (11a) which is adapted to receive the tongue-like portion when the clamp is installed over the object to be fastened thereby, and in that the tongue-receiving means (48) commences within the area of an outwardly directed first step-like portion (49) and extends from the first step-like portion (49) in the same circumferential direction as the tongue-like portion (47). An open clamp according to claim 6, characterized in that the tongue-receiving means (48) is formed by a pressed-out channel (48) in the center area of the overlapping outer band portion (11a) leaving non-pressed-out lateral band portions (11a', 11a") on both sides thereof, said lateral band portions (11a', 11a'') being raised substantially to the height of the channel within the area of the first step-like portion (49), and said channel (48) terminating within the area of a second step-like portion (45) spaced in the circumferential direction away from the free end of the outer band portion (11a) . An open clamp structure according to any one of claims 5 to 7, characterized in that, as viewed in the circumferential direction, the auxiliary spring structure is followed by the ear-like means which, in turn, is followed by said additional arrangement (45,48,49). An open clamp structure according to claims 3-7, characterized by a limiting arrangement (120,130) in the overlapping band portions within the area between the auxilary spring structure (11b) and the ear-like means (41) for protecting the auxiliary spring structure (110) against excessive stretching. An open clamp according to any one of claims 1 to 9, characterized in that the inner band portion (11b) is provided with two circumferentially extending pressed-out ribs (12,13) within at least part of the are of overlap between inner and outer band portions (11b,11a) to permit operation of the auxiliary spring structure with a minimum of friction in the installed condition of the clamp. An open clamp according to claim 10, characterized in that the inner band portion (11b) is provided with the two circumferentially extending pressed-out rib-like means (12, 13) at least within the area between the auxiliary spring structure (10) and the arrangement for tightening the clamp (41). An open clamp according to any one of claims 1 - 11, characterized in that the auxiliary spring structure (110) is connected between the end area of the outer band portion (11a) and a part of the clamping band about to pass over into the inner band portion (11b) by the outwardly extending hooks (118, 119) in the outer band portion and in said part of the clamping band. An open clamp according to any one of the preceding claims, characterized in that the auxiliary spring structure includes a number of inter-engaging leaf spring members (111, 112).

Inventors: OETIKER HANS, OETIKER, HANS
Applicants: OETIKER HANS MASCHINEN, HANS OETIKER AG MASCHINEN- UND APPARATEFABRIK
Application year: 1992
Main classification: F16L33
IPC codes: F16L33