Low profile clamp with tolerance compensation

Abstract

The invention discloses a low profile clamp with tolerance compensation. An improved tolerance compensation device (50) for a clamping structure (10) formed by a clamping strap (1) having first and second ends (2, 3) adapted to overlap each other as inner and outer clamping strap portions when the clamping structure (10) is mounted around an object to be fastened. The tolerance compensation device (50) comprises adjacent first, second and third belt regions (51, 52, 53), while the second belt region (52) has a constant bandwidth W reduction that is less than the first and third belt regions (51, 53).

Description

Technical Field

[0001] The present invention relates to a clamping structure made of a flat metal band or strip which forms a loop to tighten around an object of substantially circular cross-section, such as a hose, a pipe or a sheath. In particular, the present invention relates to a so-called "low profile clamp", i.e. a clamp having only a small radially outwardly projecting portion, resulting in a relatively small overall radial clamp profile. Furthermore, the present invention particularly relates to a so-called stepless clamp, i.e. a clamp which, in its closed state, has almost no uneven portions or steps at the inner peripheral surface. Background Art

[0002] In order to reliably assemble the clamp structure on the object to be fastened, the tolerance stack-up of the object must be taken into account. Due to their fixed closing stroke, low-profile clamps usually have a limited application range and therefore reduced tolerance stack-up coverage. Therefore, the clamp is provided with a tolerance compensation element to enable the clamp elongation to adapt to the tolerance variations of the object.

[0003] The tolerance compensating elements commonly used in the art are outwardly extending wave-shaped profiles based on accumulating / storing the belt material, which can then be plastically deformed / stretched to provide the required compensation. Such wave-shaped tolerance compensating elements are described, for example, in EP 0 697 554 A1, FR 2 470 275 A1, US 4 308 648 A and US 2009 / 0313792 A1.

[0004] However, this conventional tolerance compensation waveform has three major disadvantages:

[0005] - Their radial extension and material accumulation determine a weak clamping impact resistance. In fact, when struck by an external body during operation, the wave-type profiles in low-profile clamps have a tendency to elongate due to the impact and thus cause disengagement / spring opening of the clamping elements.

[0006] - Wave-type compensating elements usually behave too weakly in elongation. This means that the load at which they begin to elongate is usually too low (see below Figure 3 ), resulting in reduced performance of the clamping elements and therefore increased risk of potential leakage.

[0007] -Including compensating wave patterns in the fixture design requires repositioning other features, thus typically also increasing the overall strip length.

[0008] Another example of tolerance compensation elements used in the prior art is a slot-shaped opening in the belt material. This is described, for example, in EP 0 697 555 A1. US 1 705 895 A, US 4 998 326 A and US 4 987 651 A also suggest enhancing stretchability by combining those slot-shaped openings with recesses at the lateral edges of the belt material.

[0009] However, these prior art solutions achieve unsatisfactory results. In particular, the shape of the groove-shaped tolerance compensation element allows only limited performance with respect to stretchability (or elongation) and a limited maximum resistance of the belt clamp before it breaks. Summary of the invention

[0010] One object of the present invention is to improve the overall performance of the clamp structure in terms of its elongation and maximum resistance behavior without compromising the cost and usability of the clamp.

[0011] This object is achieved by the clamping structure defined in claim 1. The other claims relate to preferred embodiments.

[0012] According to the invention, the clamping structure is formed by a clamping strip which comprises a tolerance compensation device in the form of a section of reduced cross-section, i.e. a section in which the bandwidth is concavely reduced from a first bandwidth to a second bandwidth to impart stretchability to the clamping strip in its longitudinal direction. More specifically, the tolerance compensation device comprises adjacent first, second and third band regions, while the second band region has a constant bandwidth that is smaller than the first and third band regions.

[0013] The tolerance compensation device of the invention is able to provide an almost linear elongation (mainly through plastic deformation) before the maximum closing force is achieved. The invention achieves an increase in the maximum achievable stroke before the clamping element breaks. In particular, compared with the compensation waveforms known in the art, this solution shows the following advantages:

[0014] -Without radial extension and material accumulation, the risk of detachment and poor impact resistance is mitigated / avoided.

[0015] - Since the tolerance compensation is based on the elongation of the material over the portion of reduced cross-section, this elongation occurs at high closing force values, thus reducing the risk of deterioration of the clamp stiffness.

[0016] - This solution shows only a slight reduction in radial compression, so there is only a limited reduction in radial load performance.

[0017] According to a preferred embodiment, the longitudinal extension of the second belt region is greater than the longitudinal extension of the first or third belt region, but less than the sum of the longitudinal extensions of the first and third belt regions. This proves to provide the best properties with regard to the trade-off between material elongation and maximum rupture force.

[0018] For similar reasons, the reduction / increase in the bandwidth in the first and / or third band regions should preferably be linear and / or symmetrical with respect to the longitudinal center axis of the clamping band and / or with respect to a cross section through the second band region orthogonal to the longitudinal direction. Furthermore, the angle at which the transverse band edges converge in the first and / or third band regions towards the constant width at the second band region should preferably be between 130° and 170°, more preferably between 140° and 160°, most preferably between 145° and 155°.

[0019] According to a most preferred embodiment, the tolerance compensating means is at least partially, preferably completely, formed at the second end portion, which forms a portion of the outer clamping band overlapping the first end portion when the clamping structure is mounted around the object to be fastened. In particular, the tolerance compensating means can be formed between the free end of the clamping band at the second end portion and a radial step formed in the second end portion to provide a larger radial dimension for the portion of the second end portion adapted to overlap the first end portion of the clamping band when the clamping structure is mounted around the object to be fastened. Such positioning of the tolerance compensating means close to the clamping portion where the tensioning hook and the tongue receiving channel are placed has proven to improve the stretchability compared to prior art solutions having a tolerance compensating element in the longitudinal center portion.

[0020] In a particularly preferred embodiment, the clamping structure has a tensioning hook provided with a window formed by cutting out the strip material in a transverse central portion of the clamping strip, and the cut window is formed at least partially in the third strip region. Thus, the material stretchability in the third strip region is supported, resulting in optimized elongation properties.

[0021] Similarly, the clamping structure in the embodiment may include a tongue portion formed at the first end of the clamping band and a tongue receiving channel formed at the second end of the clamping band. The tolerance compensation is then positioned so that the tongue receiving channel is at least partially formed within the first band area. This arrangement has also been shown to help achieve the desired elongation characteristics.

[0022] With regard to manufacturing aspects, all three band regions of the claimed tolerance compensation device can be formed by cutting the band material from the normal width of the clamping band at the transverse band edges. Thus, the clamping structure with the tolerance compensation device of the invention can be obtained from a flat band of steel material in a relatively simple and inexpensive cutting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Detailed embodiments of the present invention will now be described in more detail below with reference to the accompanying drawings, in which:

[0024] Figure 1 is a top view of a clamping structure according to an embodiment in a flat (unrounded) state;

[0025] Figure 2 yes Figure 1 A perspective view of the clamping structure shown; and

[0026] Figure 3 The behavior of the clamping structure of the embodiment in comparison with clamping structures having other compensation elements is shown in a displacement-force diagram obtained by finite element analysis (FEA). DETAILED DESCRIPTION

[0027] In this specification, the terms "radial", "axial" and "circumferential" refer to the overall geometry of the clamp, which in its closed state is generally a ring with a certain radius and circumference. The clamp is designed to enclose a pipe, hose or sheath extending substantially in the axial direction.

[0028] Figure 1 and Figure 2 The clamping structure 10 is shown in a flat (non-circular) state. The clamping structure 10 is made of a flat metal strip or strip 1 by various cutting and deformation or stamping steps generally known in the art. The tip of the first circumferential end 2 has a tongue portion 11 of minimum width, which is suitable for being received in a tongue channel 19 at the inner side of the second end 3 of the strip 1. The tongue portion 11 has a radial protrusion 11a, which is received in a guide channel 19a of the tongue receiving channel 19. At the end of the tongue receiving channel 19, there are radial steps 17 on both lateral sides for abutting against the edges on both lateral sides formed at the root of the tongue portion 11. The height of the radial step 17 corresponds to the thickness of the flat strip material 1. Therefore, the clamping structure 10 provides a substantially step-free inner surface facing the object to be fastened in its closed state.

[0029] Extending circumferentially from the tongue portion 11 in the direction towards the second end 3 of the strip 1, the clamping structure 10 has a pre-assembly hook 12 adapted to be received in a hole 42 of the second tensioning hook 40 in a pre-assembly state in which the flat clamping strip is in a circular but not yet in a final closed configuration. The hole is formed by cutting the strip material in the axial direction before forming the coined hook 40 without taking material away from the clamping strip 1.

[0030] The connecting or load holding hook 20 and the first tensioning hook 30 are circumferentially adjacent to the preassembly hook 12. The connecting hook 20 has a free edge portion 21 which forms the radially outermost tip of the hook 20 and serves as an engagement tooth which is adapted to be received in the hole 42 of the second tensioning hook 40 in the closed state of the clamping structure 10. The edge portion 21 is directed in the circumferential direction towards the second end portion 3 so that when the two end portions 2 and 3 are pulled circumferentially away from each other in the closed state of the clamp 1, the edge portion 21 hooks into the hole 42. The connecting hook 20 also has a rear surface in the circumferential direction opposite to the edge portion 21 which has a smooth radial bevel and provides a slope for the outermost end of the second end portion 3 during the closing operation of the clamping structure 10.

[0031] The first and second tensioning hooks 30, 40 are both provided with toothed protrusions 31, 41 facing each other in the circumferential direction. These toothed protrusions 31, 41 allow the jaws of the pliers (not shown) that engage with the first and second tensioning hooks 30, 40 to form a non-slip form fit during the closing operation of the clamping structure 10.

[0032] The side rails 13A, 13B are formed as additional reinforcement ribs at the left and right lateral sides of at least the portion of the first end portion 2 where the connecting hook 20 and the first tensioning hook 30 are formed. The side rails 13A, 13B are formed to extend substantially in the longitudinal (= circumferential) direction of the strip material 1, and preferably extend up to the region where the tongue portion 11 is formed. This is to prevent the tongue portion 11 from being kinked during the closing of the clamp.

[0033] The clamping structure 10 is also provided with a tolerance compensation device 50 at the second end portion 3, more specifically between the radial step 17 and the free end of the second end portion 3. The tolerance compensation device 50 is provided by simply but effectively reducing the conventional bandwidth W 完整 Reduce to a smaller bandwidth W 减小 to achieve.

[0034] In the embodiment shown, the tolerance compensation device 50 comprises three consecutive belt regions 51-53 along the longitudinal direction of the clamping belt 1. In the first belt region 51, the belt width extends from the two transverse belt edges from the full or normal belt width W to the full or normal belt width W. 完整 decreases linearly and symmetrically to the reduced bandwidth W 减小 In the second band region 52, the bandwidth is reduced to the bandwidth W 减小 In the third belt region 53, the belt width decreases from the two transverse belt edges to the belt width W. 减小 increases linearly and symmetrically to the normal bandwidth W 完整 .

[0035] The angle at which the transverse belt edge of the first belt region 51 intersects the transverse belt edge of the second belt region 52 (i.e., the angle between the transverse belt edges of the first belt region 51 and the second belt region 52 and opening toward the outside) is about 150°. Similarly, the angle between the transverse belt edges of the second belt region 52 and the third belt region 53 is about 150°.

[0036] The illustrated embodiment may be modified without departing from the scope of protection. For example, the above-mentioned angles may take other values, preferably in the range of 130° to 170°. In addition, the first belt area 51 and / or the third belt area 53 may reduce / increase the bandwidth non-linearly or in a non-symmetrical manner (e.g., only on one lateral side). In addition, the bandwidth at the third belt area 53 may be smaller than the bandwidth at the first belt area 51.

[0037] The second belt region 52 extends with a greater longitudinal extension than each of the first belt region 51 and the second belt region 53, but is shorter than the total longitudinal extension of the combination of the first belt region 51 and the second belt region 53. In the embodiment shown, the ratio 51:52:53 of the longitudinal extension of the first to third belt regions is approximately 3:4:3.

[0038] As in the current Figure 1 As can be best seen in FIG. 4 , the second tensioning hook 40 is provided with a central cut window 43 which protrudes into the third belt area 53. In the cut window 43, material is taken away from the central part of the clamping belt 1. The cut window 43 weakens the material strength of the clamping belt 1 in the central part of the third belt area 53 to a desired extent. This supports the overall stretchability of the clamping structure 10 in the longitudinal direction.

[0039] Likewise, the guide channel 19a of the tongue receiving channel 19 protrudes into the first belt region 51. The guide channel 19a has a larger radial dimension than the belt portion between the radial step 17 and the free end of the second end portion 3. Therefore, the guide channel 19a weakens the material strength of the clamping belt 1 in the central part of the first belt region 51 to a certain extent. This also supports the overall stretchability of the clamping structure 10 in the longitudinal direction.

[0040] Now refer to Figure 3 Results of the Finite Element Analysis (FEA) are discussed. As will be explained therein, the proposed shape of the tolerance compensation device 50 according to the present embodiment leads to better performance compared to the prior art shapes.

[0041] FEA compares the full band 100 ( Figure 3), the proposed solution 105 (thick dashed curve) and several other configurations 101-104 (other dotted or dashed curves). For all compared configurations, the same size and shape of the cut window 43 has been considered in the central bandwidth portion.

[0042] from Figure 3 As can be seen in Fig. 1 , the proposed solution 105 provides a rigid tensile behavior, especially at low displacement values ​​(similar to the full belt 100 without any compensation elements, displacement range 0-2 mm). Later (displacement range 4-5 mm), it can be noticed that the proposed solution 105 provides an increased elongation as the load increases, thus facilitating the tolerance compensation of the clamping structure 10 without significantly reducing the load response. This results in a better overall clamping performance.

[0043] In the case of other tolerance compensation configurations of the prior art 101, 102 and comparative examples 103, 104, it can be seen that the wavy profile 101 elongates too much at low force values ​​compared to the proposed solution 105, and the other geometries 102-104 provide lower force response (strength) and lower maximum elongation before failure.

[0044] In particular, for the prior art case of the tolerance compensation wave pattern shown in the longitudinal cross-section in top views 101A and 101B, there is too much elongation at forces in the range of 500 to 3,000N.

[0045] In the prior art case of the double groove tolerance compensating element 102, the maximum elongation before failure was less than 3 mm, while the present embodiment 105 reaches about 5 mm.

[0046] Comparative Example 103 provides a curved concave portion of a constant width band-like region without reduced size. The FEA curves for this solution 103 remain well below the FEA curves for the present solution 105. This means that the load response and clamping force are generally weaker than in the present embodiment.

[0047] Comparative Example 104 provides a much longer band region of constant width with reduced dimensions than the present solution 105, while the reduced width dimensions are smaller than the reduced dimensions W of the present embodiment. 减小 Again, the load response is worse than in the present example, and in addition, the maximum elongation before failure is lower, namely at about 4.3 mm.

[0048] In summary, the present invention provides an improved tolerance compensation device 50 for a clamping structure 10 formed by a clamping strip 1 having first and second ends 2, 3 adapted to overlap each other as inner and outer clamping strip portions when the clamping structure 10 is mounted around an object to be fastened. The tolerance compensation device 50 comprises adjacent first, second and third strip regions 51-53, with the second strip region 52 having a constant strip width W less than the first and third strip regions 51, 53. 减小 .

[0049] Reference numerals list

[0050] 1 Clamping belt

[0051] 2First end

[0052] 3 Second end

[0053] 10 Clamping structure

[0054] 11 Tongue part

[0055] 11a Radial protrusion

[0056] 12 pre-assembled hooks

[0057] 13A, 13B side rails

[0058] 17 steps

[0059] 19 tongue receiving channel

[0060] 19a Guide Channel

[0061] 20 Connecting hooks

[0062] 21Protruding edge part

[0063] 30 The first tight hook

[0064] 31 denticles

[0065] 40 Second tension hook

[0066] 41 denticles

[0067] 42 holes

[0068] 43 Cutting Window

[0069] 50 Tolerance compensation device

[0070] 51 First Zone

[0071] 52 Second Zone

[0072] 53 Third Zone

[0073] W 完整Full or normal width

[0074] W 减小 Reduced Width

[0075] 100 reference examples "full belt"

[0076] 101A Reference Example "Wave Type" - Top View

[0077] 101B Reference Example "Wave Type" - Cross Section

[0078] 102 Reference example "slot"

[0079] 103 Reference example "circular concave portion"

[0080] 104 Reference example "long rectangular recess"

[0081] 105 present embodiment

Claims

1. A clamping structure (10) formed by a clamping belt (1), comprising: a first end portion and a second end portion (2, 3) adapted to overlap each other as inner and outer clamping band portions when the clamping structure (10) is mounted around an object to be fastened, connecting means (11, 19, 20, 30, 40) operable to mechanically interconnect the inner clamping band portion and the outer clamping band portion, and a tolerance compensating device (50) which imparts stretchability to the clamping strip (1) in the longitudinal direction of the clamping strip (1), Characterized in that the tolerance compensation device (50) comprises the following adjacent belt areas along the longitudinal direction of the clamping belt (1): A first band region (51) wherein the lateral band width is from a first band width (W 完整 ) is reduced to less than the first bandwidth (W 完整 )'s second bandwidth (W 减小 ), A second band region (52) in which the transverse band width is within the second band width (W 减小 ) remains constant, and A third band region (53) in which the transverse bandwidth increases to a value greater than the second bandwidth (W 减小 )’s third bandwidth.

2. The clamping structure (10) according to claim 1, wherein: The third bandwidth is equal to the first bandwidth (W 完整 ).

3. The clamping structure (10) according to claim 1, wherein the longitudinal extension of the second band region (52) is greater than the longitudinal extensions of the first band region (51) and the third band region (53) but less than the sum of the longitudinal extensions of the first band region (51) and the third band region (53).

4. The clamping structure (10) according to claim 1, wherein: The transverse belt edges in the first belt region (51) and the third belt region (53) are aligned with the second belt width (W 减小 ) the transverse belt edges in the second belt region (52) form an angle between 130° and 170°.

5. The clamping structure (10) according to claim 4, wherein the transverse belt edges in the first belt region (51) and the third belt region (53) are connected to the second belt width (W 减小 ) the transverse belt edges in the second belt region (52) form an angle between 140° and 160°.

6. The clamping structure (10) according to claim 1, wherein: The tolerance compensation device (50) is at least partially formed at the second end (3), and when the clamping structure (10) is mounted around the object to be fastened, the second end (3) forms the outer clamping band portion overlapping the first end (2).

7. The clamping structure (10) according to claim 1, wherein the reduction of the bandwidth in the first bandwidth region (51) is linear.

8. The clamping structure (10) according to claim 1, wherein the increase in the bandwidth in the third band region (53) is linear.

9. The clamping structure (10) according to claim 1, wherein: The reduction of the bandwidth in the first band region (51) and the increase of the bandwidth in the third band region (53) are symmetrical with respect to the longitudinal center axis of the clamping band (1).

10. The clamp structure (10) according to claim 1, wherein: The reduction of the bandwidth in the first bandwidth region (51) and the increase of the bandwidth in the third bandwidth region (53) are symmetrical with respect to a cross section through the second bandwidth region (52) orthogonal to the longitudinal direction.

11. The clamping structure (10) according to claim 1, wherein A radial step (17) is formed in the second end (3) of the clamping band (1) to provide a greater radial dimension to the portion of the second end (3) adapted to overlap the first end (2) of the clamping band (1) when the clamping structure (10) is mounted around an object to be fastened, and A tolerance compensation device (50) is formed between the radial step (17) and the free end of the clamping band (1) at the second end (3).

12. The clamping structure (10) according to claim 1, wherein The connecting device (11, 19, 20, 30, 40) comprises a tensioning hook (40) having a window (43) formed by cutting the strip material in a transverse central portion of the clamping strip (1), and A cut window (43) is formed at least partially within said third belt region (53).

13. The clamping structure (10) according to claim 1, wherein The connecting device (11, 19, 20, 30, 40) comprises a tongue portion (11) formed at the first end (2) of the clamping band (1) and a tongue receiving channel (19) formed at the second end (3) of the clamping band (1), and At least a portion (19a) of the tongue receiving channel (19) is formed in the first belt region (51).

14. The clamping structure (10) according to claim 1, wherein all three band regions (51-53) of the tolerance compensation device (50) are formed by cutting away band material from the transverse band edges of the clamping band (1) to reduce the width of the clamping band (1) from the first width (W 完整 ) is reduced to the second width (W 减小 ) to form.

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