Clamp structure with spring element

Abstract: An open clamp structure in which overlapping band portions (11a, 11b) are mechanically connected by a spring (25) separate from the clamping band (11); the spring (25) is of low profile having a top portion (26) and lateral portions (27a, 27b) passing over into mutually facing end portions (28a, 28b) which are provided with tongue-like extensions (29a, 29b) adapted to engage in tunnel-shaped embossments (17, 18) in corresponding parts of the clamping band. Means (40, 140) for limiting the extent of stretching to which the spring can be subjected and also providing at the same time a guide function to keep overlapping band portions mutually aligned includes either two tab-like members (41a, 41b) extending in the longitudinal direction within two narrow slot-like openings (42a, 42b) only slightly wider than the thickness of the clamping band and of predetermined length or a tunnel-shaped embossment (141) in the inner band portion extending in an elongated opening (142) of only slightly larger width than the embossment to provide the guide function.

Description: The present invention relates to a clamp, and more particularly to a "stepless" clamp with a separate spring element. A clamp of this type, which has the features included in the first part of claim 1, is known from US-A-5,138,747. In this prior-art clamp, the mutually facing ends of leaf spring members, which form the auxiliary spring, terminate in end portions bent to point in the direction toward the top portions of the leaf spring members while the connection with inner and outer band portions takes place by means of substantially S-shaped hooks adapted to engage in apertures provided in the inner band portions. As the strength of the hooks bent out of the band portions depend on properties of the clamping band material, such as the thickness thereof, a limit exists in practice for the maximum spring force which this connection can withstand without the danger of disengagement. Additionally, the extent of relative movement between the inner and outer band portions, and thus the extent to which the auxiliary spring can be subjected to stretching forces, is limited by a hook that extends outwardly to engage in an oversized aperture. Though the limiting action of the known clamp proved reasonably successful, the outwardly extending hook was unable to provide a completely satisfactory guide function to keep the inner and outer band portions in proper mutual overlapping alignment. SUMMARY OF THE INVENTION It is an object of the present invention to provide a clamp with the capability of absorbing greater forces, i.e. permitting the use of a stronger auxiliary spring. This object is met by the invention as defined in claim 1. In accordance with an embodiment of the invention, the auxiliary spring is a low-profile spring with a convex top portion having a large radius of curvature passing over into convex lateral portions of a much smaller radius of curvature than the top portion and terminating in mutually facing tongue-like extensions which are adapted to engage in tunnel-shaped embossments pressed out of the respective band portions by deep-drawing after the formation of two transverse cuts. These embossments are located in the end area of the outer band portion just ahead of the beginning of the area of overlap. An improved guide and limiting action can be obtained by the use of two tab-like members bent out of the inner band portion about axes extending in the longitudinal direction of the clamping band and adapted to engage in narrow slots of predetermined length. Alternatively, the improved guide and limiting action can be realised with the use of a tunnel-shaped embossment in the inner band portion adapted to engage in an elongated opening again of predetermined length. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, features 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 clamp structure in accordance with the present invention; Figure 2 is a perspective view of the spring member; Figure 3 is a partial cross-sectional view through the clamp structure of Figure 1; Figure 4 is a plan view on the spring structure of Figure 3, taken along line 4-4; Figure 5 is a partial top plan view on the guide and limiting arrangement of the clamp structure in Figure 1; Figure 6 is a partial plan view on a modified embodiment of a guide and limiting arrangement for use with the clamp structure of Figure 1; and Figure 7 is a cross-sectional view, taken along line 7-7. DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, and more particularly to Figures 1 through 5, reference numeral 10 generally designates a clamp structure with improved spring action according to the present invention which includes a clamping band 11 having overlapping inner and outer clamping band portions 11b and 11a , respectively. The clamp structure of Figures 1 through 5 further includes a so-called "Oetiker" ear generally designated by reference numeral 20 including generally outwardly extending leg portions 21a and 21b interconnected by a bridging portion 22 provided with reinforcing means 23 in the form of a longitudinally extending groove V-shaped in transverse cross section and of canoe-like shape in plan view or preferably of a substantially rectangular shallow depression as more fully disclosed in US-A-5,282,295. To provide an internal clamping surface devoid of step, offset or discontinuity within the area of the end of the inner clamping band portion, the inner clamping band portion terminates in a tongue-like extension 12 adapted to engage in a tongue-receiving means which, in the embodiment of Figure 1, is formed by a centrally disposed pressed-out channel leaving on both sides lateral band portions 14a and 14b which pass over into the outer band portion 11a by way of step-like portions 15a and 15b as more fully disclosed in US-A-4,299,012. However, in lieu of a centrally disposed channel, a transition devoid of any step, offset or discontinuity in the inner clamping surface can also be achieved by an aperture beginning within the step portions 15a and 15b as more fully disclosed in my prior U.S. Patent 4,315,348. It should also be noted that in the non-contracted condition of the ear-like structure 20 , the gap underneath the same is already covered by the full band width of the inner band portion so that any gap remaining after contraction of the ear will be covered by the full band width of the inner band portion 11b . The auxiliary spring generally designated by reference numeral 25 is of relatively flat construction and includes a convexly shaped top portion 26 having a large radius of curvature which passes over on both sides into convexly shaped lateral band portions 27a and 27b having a radius of curvature which is much smaller than the radius of curvature of the top portion 26 . The lateral portions 27a and 27b terminate in mutually facing end portions 28a and 28b , each provided with a short, centrally arranged tongue-like extension 29a and 29b . The tongue-like extensions 29a and 29b are thereby adapted to engage in tunnel-shaped embossments 17 and 18 which are obtained by pressing out and deep-drawing clamping band material after two transverse cuts for each embossment in the respective clamping band area. The tunnel-shaped embossment 17 is thereby located in the clamping band just ahead of the free end of the outer clamping band portion 11a , i.e., before the clamping band 11 passes over into the overlapped clamping band portion 11b while the tunnel-shaped embossment 18 is located within the end area of the outer band portion 11a . The auxiliary spring 25 and its connection with the clamping band portions thereby represents the mechanical connection for the open-type clamp structure which produces a spring action. The clamp structure of Figures 1 through 5 is also provided with a guide and limiting means generally designated by reference numeral 40 which consist of two transversely spaced, longitudinally extending tab-like members 41a and 41b pressed out of the inner band portion 11b about axes extending in the longitudinal direction of the clamping band (Figure 4) after two substantially U-shaped cuts. The tab-like members 41a and 41b are thereby adapted to engage in parallelly extending narrow slots 42a and 42b of predetermined length which determine the extent to which the spring 25 can be subjected to tensional forces. Additionally, the presence of the narrow slots 42a and 42b only slightly wider than the tab-like members 41a and 41b assures a good guiding function of the overlapping band portions 11b and 11a which avoids misalignment of these overlapping band portions. The length of the slots 42a and 42b limits the extent to which the spring 25 can be subjected to forces as a result of tolerance compensation and/or temperature changes or pressure fluctuations of the medium carried by the hose. The clamp structure according to Figures 1 through 5 offers significant advantages over the pre-existing clamp structures. On the one hand, it facilitates assembly of the clamp structure and, more particularly, of the spring 25 with the use of the tool engaging in the convexly shaped lateral portions 27a and 27b and spreading the same apart to be released after the tongue-like extensions 29a and 29b are aligned with the tunnel-shaped embossments 17 and 18 which then produces the mechanical connection. Similarly, the mechanical connection can be easily disconnected by merely spreading apart the lateral portions 27a and 27b of the auxiliary spring to permit disengagement of the tongue-like portions 29a and 29b from the tunnel-shaped embossments 17 and 18 . Moreover, the auxiliary spring 25 of this invention also has a relatively low profile so that it can also be used with so-called earless clamp structures in which an "Oetiker" ear is omitted to avoid outwardly projecting parts. For example, the spring 25 may also be used in a low profile clamp of the type disclosed in US-A-4,492,004. It is only necessary to cut the clamping band and interconnect the thus open band portions in this patent with the use of the auxiliary spring connection as disclosed in this application. This will provide a spring action for the earless low profile clamp structure of US-A-4,492,004 and provide also tolerance compensation for this type of clamp. Moreover, in that case, the mechanical guide and limiting means 40 as well as the mechanical guide and limiting means 140 of Figures 6 and 7 will also perform the additional task that the diameter of the installed clamp cannot be increased beyond the allowable limit when the clamp and hose is pulled off in the axial direction. In other words, the clamp connection cannot be pulled over the bead of the nipple because the band of the stepless, earless clamp will not yield; and the spring element cannot yield additionally as it is limited mechanically. Once the limit is reached, the connection with such a stepless, earless clamp then becomes a ring which cannot increase in diameter. Figures 6 and 7 illustrate a modified embodiment of a guide and limiting means generally designated by reference numeral 140 which consists of a tunnel-shaped embossment 141 pressed out by deep-drawing from the inner clamping band after two transverse cuts which is adapted to engage in an elongated opening 142 having a width only slightly larger than the width of the tunnel-shaped embossment 141 to assure proper guidance as well as limiting action. Though it is understood that the present invention is not limited to the following indications, a typical example of a clamp structure in accordance with the present invention, given only for illustrative purposes, is as follows: The clamping band may have a width of about 12 mm. and a thickness of about 0.8 mm. and may be made from a stainless steel X5CrNi18 10. The spring 25 also has a width of about 12 mm. and is made from a material Ck60. The remaining dimensions may be chosen as known to those skilled in the art to meet the particular requirements of a given application. The guide and limiting arrangement of Figure 5 as also of Figure 6 is not limited to the particular clamp structure as disclosed in the instant application but may be used to advantage wherever a guide and limiting function is desirable in connection with overlapping band portions. While I have shown and described two embodiments 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. As mentioned before, the spring action with the use of spring 25 and its interconnection may also be used with so-called earless low-profile clamps as also with so-called screw-type clamps as disclosed in US-A-4,521,940. Additionally, the spring 25 may also consist of one or several leaf springs though a solid spring member is preferable, particularly where low profile is important. Moreover by choosing the material for the spring 25 , its spring characteristics can also be preselected for different applications. Thus, the present invention is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Claims: An open clamp, comprising a clamping band (11) having overlapping band portions (11a, 11b), means (20) for tightening the clamp about an object to be fastened thereby and further means operatively connecting overlapping band portions, said further means including spring means (25) separate from the clamping band (11) and operable to provide a predetermined elastic tightening force in the presence of forces seeking to increase the diametric dimensions of the clamp, said spring means (25) being of at least partly convex configuration including mutually facing end portions (28a, 28b), and connecting means operatively connecting said spring means (25) with the clamping band (11) including first means (17, 18) located in the end area of the outer band portion (11a) and within an area of the clamping band (11) just ahead of the end of the outer band portion (11a) where the clamping band passes over into the inner band portion (11b), and second means (29a, 29b) at the mutually facing end portions (28a, 28b) of said spring means (25) operable to engage said first means (17, 18), characterised in that said first means are tunnel-shaped embossment means (17, 18) formed in the clamping band (11) by transverse cuts, and said second means are tongue-like extensions (29a, 29b) formed centrally at the respective ends of said spring means (25). The clamp of claim 1, wherein said tunnel-shaped embossment means (17, 18) are formed by deep-drawing the respective clamping band portions after the formation of said transverse cuts. The clamp of claim 1 or 2, comprising additional means (12, 13, 15a, 15b) eliminating any gap, discontinuity or step in the internal clamping surface in such a manner that the gap of the spring means (25) is bridged by the full band width of a part of the clamping band (11) itself. The clamp of claim 3, wherein the additional means (12, 13, 15a, 15b) includes a tongue-like extension (12) at the inner band end and a tongue-receiving means (13) in the outer band portion (11a). The clamp of claim 4, wherein said additional means (12, 13, 15a, 15b) includes lateral band portions (14a, 14b) raised to the radial level of the outer band portion (11a) within the area of step-like portions (15a, 15b). The clamp of any preceding claim, further comprising guide means (40, 140) for mutually guiding the overlapping band portions and simultaneously protecting the spring means (25) against excessive stretching. The clamp of claim 6, wherein said guide means (40) includes two tab-like members (41a, 41b) spaced from one another in the clamping band transverse direction and bent out of the inner band portion (11b) about axes extending in the clamping band longitudinal direction, said two tab-like members (41a, 41b) engaging in two parallel slots (42a, 42b) extending in the longitudinal direction and having a width which is only slightly larger than the thickness of the clamping band (11), the length of said slots (42a, 42b) determining the extent to which the spring means (25) can be subjected to stretching. The clamp of claim 6, wherein said guide means (140) includes a tunnel-shaped embossment (141) in the inner band portion (11b) pressed out from the inner band portion by deep-drawing after the formation of two substantially transverse cuts, said embossment (141) being operable to engage in an opening (142) in the outer band portion (11a) extending in the longitudinal direction thereof, said opening (142) being only slightly larger than the embossment (141) to provide a guide function and having a length determining the extent to which the spring means (25) can be subjected to stretching. The clamp of any preceding claim, wherein said tightening means includes a plastically deformable ear-like means (20) whose gap is covered from below by the full band width of the inner band portion (11b).

Inventors: OETIKER HANS, OETIKER, HANS
Applicants: OETIKER HANS AG, HANS OETIKER AG
Application year: 1996
Main classification: F16L33
IPC codes: F16L33, B65D63