Clamping system with leaf spring for holding a cylindrical tank

Abstract

The invention relates clamping system for holding a cylindrical tank, comprising a bracket (12) for supporting the cylindrical tank, a strap (14) for fastening the cylindrical tank on the bracket (12), the strap (14) having a first end and a second end, tightening means (28) for connecting first end and the second end and being operable to increase or reduce the diameter encircled by the strap (14), and elastic compensation structure (18) capable of compensating for the predetermined length variations of the tensioning band corresponding to the cyclically varying dimensions of the tank. It is proposed that the elastic compensation structure (18) includes a leaf spring (20) supported by the bracket (12).

Description

[0001] Clamping system with leaf spring for holding a cylindrical tank

[0002] The present invention relates to a clamping system according to the preamble of claim 1 .

[0003] Known clamping systems use a strap made from a flat metal band or strip to be fastened around an obj ect of substantially circular cross-section such as fuel gas tank, particularly a hydrogen tank . Fuel tanks , such as compres sed natural gas and compressed hydrogen gas tanks , need to be secured to a structure of a building or vehicle for proper holding and safe transportation . Further , the high pres sure tanks expand and contract during refuelling and engine fuel consumption cycles . It is therefore required to find clamping systems which are not only able to secure the fuel tanks but also have compensation means configured to accommodate expansion / extraction cycles of the tank perimeter .

[0004] The document CN 107 035 966 A describes an example of such a conventional clamping system. In this prior art solution, the compensation means is realised by a strap portion of corrugated cros s section .

[0005] A disadvantage encountered with those conventional clamping systems is that it is relatively difficult to design the spring force of the compensation element . It would be preferable to have a compensation element whose upper and lower limits , spring constant , etc . can be tailored exactly to the requirements of the fuel tank .

[0006] The document US 9 , 909 , 535 A discloses another example of a conventional clamping system . In this prior art solution , the tank is secured by an L-shaped bracket screwed to a U-shaped strap . A wedge-shaped gas ket of flexible material is sandwiched between the strap and the tank to prevent longitudinal sliding and rotation of the tank during transportation . Further , a tensioner spring is provided at the screw connection between the L-shaped bracket and the U-shaped strap to compensate for radial expan- sion / extraction of the tank . More specifically, the tensioner spring is placed directly at the tensioning means such as a screw connecting two trunnions in strap loops at the tensioning ends of the strap .

[0007] A disadvantage of this conventional solution is that it is rather space consuming and fragile since the spring element proj ects tangentially from the tensioning ends of the strap . Also , the required spring force has its highest value at the tens ioning means so that the compensation element needs to withstand relatively high stress .

[0008] An obj ect of the present invention is to provide a clamping system which is very robust , and which is more compact than conventional solutions in that it requires less mounting space .

[0009] This obj ect is achieved by the clamping system defined in claim 1 . The dependent claims relate to preferred embodiments .

[0010] The invention relates to a clamping system for holding a cylindrical tank . The clamping system comprises a bracket for supporting the cylindrical tank, a strap for fastening the cylindrical tank on the bracket , the strap having a first end and a second end, tightening means for connecting first end and the second end and being operable to increase or reduce the diameter encircled by the strap , and an elastic compensation structure capable of compensating for the predetermined length variations of the strap corresponding to the cyclically varying dimens ions of the tank .

[0011] It is proposed that the elastic compensation structure includes a leaf spring supported by the bracket . This structure does not require additional space as it is integrated into the bracket and is further very robust .

[0012] The inventors further propose that the leaf spring has a first end formed as a j ournal bushing being supported by a bolt extending through a space between lateral webs of the bracket , and a second end supported by an element of the bracket . The longitudinal direction of the leaf spring is preferably oriented in the circumferential direction of the system and of the tank . The same applies for the bracket and for the lateral webs thereof .

[0013] In one embodiment of the invention, the leaf spring is pre-bent with a convex surface facing the tank and supporting the tank such that the leaf spring is loaded when the tightening means is tightened .

[0014] It is further proposed that the bracket has first and second openings through which the strap extends so that a circumferential portion of the strap is disposed beneath the leaf spring . By virtue of this structure , it is possible to use a continuous strap formed as a loop rather than two or more sections of the strap each connecting the bracket with one end of the ten

[0015] In a second embodiment of the invention, the leaf spring is prebent with a convex surface facing the strap and deflecting the strap such that the leaf spring is loaded when the tightening means is tightened .

[0016] The embodiments may be combined, e . g . by providing one leaf spring press ing in the direction of the tank and another leaf spring press ing toward the strap .

[0017] In a preferred embodiment of the invention, the bracket includes rollers or bolts for guiding the strap through the openings .

[0018] The inventors further propose that the bracket includes at least one interface element disposed between the bracket and tank .

[0019] It is further proposed that the bracket includes at least one opening for visually verifying a deflection status of the leaf spring .

[0020] I a preferred embodiment of the invention , the strap includes a metal band with a rubber inlay . The inventors further propose supporting the leaf spring on shoulder portions on both sides of the openings of the bracket in a form-fitting manner via teeth . This provides enhanced stability and reliability . This form-fitting connection eliminates the need for additional fastening elements such as bolts and splints , thereby reducing the number of components and simplifying the as sembly process . The elimination of these additional components also reduces the ris k of failure due to loosening of bolts or los s of splints during operation .

[0021] When the teeth are arranged immediately left and right of the strap in the band area , this configuration provides a compact design where the force transfer between the strap and the leaf spring is optimized . The proximity of the teeth to the band area ensures that the spring force is applied precisely where needed , leading to more predictable elastic compensation behavior and more uniform force distribution .

[0022] Alternatively, when the teeth are positioned at the laterally outer ends of the bracket , separated from the band area, this arrangement provides enhanced lateral stability of the leaf spring . The wider support base prevents unwanted lateral movement or twisting of the leaf spring during operation, particularly when the cylindrical tank undergoes expansion / contraction cycles .

[0023] The formation of the leaf spring as a multilayer leaf spring comprising several layers of spring material offers s ignificant advantages in terms of customizability and performance optimi zation . This structure allows for fine-tuning of the spring characteristics to match specific reguirements of different tank si zes , materials , and operating conditions .

[0024] By varying the number, thicknes s , and length of the individual spring layers , the spring force , deflection range , and fatigue resistance can be precisely tailored without changing the overall dimens ions of the clamping system . This adj ustability is particularly advantageous when adapting the clamping system to different tank sizes or when accommodating tanks with different expansion characteristics .

[0025] Additionally, the multilayer configuration enhances the failsafe characteristics of the system. In case one layer develops fatigue cracks , the remaining layers can still provide sufficient elastic compensation to maintain secure holding of the tank until maintenance can be performed .

[0026] The direct securing of the leaf spring to the bracket without rollers , j ournal bushings , or bolts significantly reduces the complexity of the clamping system . This s implification leads to lower manufacturing costs , easier assembly, and reduced maintenance requirements . The elimination of moving parts such as rollers and j ournal bushings also increases the overall reliability of the system, as these components are typically subj ect to wear and are potential points of failure .

[0027] Furthermore , this direct connection results in a more compact design that requires less installation space , which is particularly beneficial in applications where mounting space is limited , such as in fuel cell vehicles .

[0028] The provis ion of a rubber inlay on the top surface of the bracket serving as an interface element between the bracket and the tank offers multiple advantages . First , it provides protection for the tank surface against abrasion or damage that might otherwise occur from direct contact with the metal bracket .

[0029] Second , the rubber inlay contributes to the elastic compensation function of the system by providing an additional cushioning effect that can absorb minor vibrations and movements of the tank , thereby reducing stres s on both the tank and the clamping sys tem .

[0030] Third, the rubber material , preferably EPDM, NBR or other suitable polymer, ensures correct connection performance by increas- ing friction between the tank and bracket , thus preventing unwanted movement or rotation of the tank during operation .

[0031] These additional features , when implemented individually or in combination, s ignificantly enhance the performance , reliability, and versatility of the clamping system for securely holding cylindrical tanks while accommodating their dimensional changes during operation .

[0032] Further features and advantages will be apparent from the following des cription of the embodiments and figures . The entire description, claims and figures dis close features of the invention in specific embodiments and combinations . The person s killed in the art will also cons ider the features individually and combine them into further combinations or sub-combinations to adapt the invention , as defined in the claims , to his needs or to specific fields of application .

[0033] The figures illustrate the following :

[0034] Fig . 1 illustrates a hydrogen tank with a clamping structure according to a first embodiment of the invention;

[0035] Fig . 2 illustrates the clamping structure of Fig . 1 ;

[0036] Fig . 3 illustrates a partial section of the clamping structure of Fig . 1 and 2 ;

[0037] Fig . 4 is a longitudinal view of the hydrogen tank with the clamping structure of Fig . 1 ;

[0038] Fig . 5 is a longitudinal view of a hydrogen tank with a clamping structure according to a second embodiment of the invention;

[0039] Fig . 6 illustrates a hydrogen tank with a clamping structure according to a third embodiment of the invention, wherein the leaf spring is supported on shoulder portions via teeth arranged immediately left and right of the band area and is formed as a multilayer leaf spring ; and Fig . 7 illustrates a hydrogen tank with a clamping structure according to a fourth embodiment of the invention .

[0040] In the present specification, the terms "radial" , "axial" , "tangential" and " circumferential" refer to an overall geometrical form of the clamping system which, in its closed state, is generally a ring having a certain radius and circumference. The clamping system is designed for embracing a cylindrical element such as a fuel tank, in particular a tank of compressed natural gas or compressed hydrogen gas. The longitudinal axis of the tank body extends substantially in the axial direction which corresponds to the width direction of the band material of the clamping straps. The straps are made from a flat metal band or strip by various cutting and deforming or embossing steps which are generally known in the art.

[0041] Fig. 1 illustrates a hydrogen tank 10 with a clamping structure according to a first embodiment of the invention. The clamping system is configured to mount a hydrogen tank 10 that is placed on a bracket 12 which is placed on the ground or on the floor of a vehicle (not illustrated) . Several clamping systems of this kind may be used to support the hydrogen tank 10 in multiple points in the longitudinal direction, e.g. on both ends thereof.

[0042] Figures 2 and 3 show the clamping system according to a first embodiment of the invention in more detail. The bracket 12 is an elongate sheet metal part with a base portion having fastening tabs 12a, 12b at its end portions and an essentially U-shaped profile with side walls 12c, 12d forming lateral webs. The upper edges of the side walls 12c, 12d have a concave shape with a curvature radius larger than the curvature radius of the hydrogen tank 10.

[0043] The bracket 12 has, on its longitudinal ends, first and second openings 12e, 12f through which a strap 14 extends. The bracket 12 includes rollers 16a, 16b for guiding the strap 14 through the openings 12e, 12f such that the strap 14 is disposed underneath the hydrogen tank 10 with a distance maintained by the rollers 16a, 16b. The rollers 16a, 16b are supported by bolts 18a, 18b extending through bores in the side walls 12c, 12d. The bolts 18a, 18b are secured nuts. The clamping system further comprises a strap 14 for fastening the cylindrical tank on the bracket 12 . The strap 14 has a first end and a second end at which the strap 14 is folded back to form a loop 14a , 14b , respectively . Tightening means 28 of the clamping system include trunnions inserted into the loops 14a , 14b and a tightening s crew connecting the trunnions . The tightening means 28 therefore connects the first end and the second end of the strap 14 and is being operable to increase or reduce the diameter encircled by the strap 14 by tightening or releas ing the screw .

[0044] As illustrated in Fig . 4 , the strap 14 includes a metal band 14c with a rubber inlay 14 d . The rubber inlay 14 d may made of EPDM, NBR or other polymer to protect hydrogen tank 10 surface against damage and provide correct connection performance .

[0045] The clamping system further comprises an elastic compensation structure 18 capable of compensating for the predetermined length variations of the strap 14 corresponding to the cyclically varying dimensions of the tank .

[0046] According to the invention, the elastic compensation structure 18 includes a leaf spring 20 supported by the bracket 12 . The leaf spring 20 has a first end 20a formed as a j ournal bushing being supported by a bolt 22 extending through bores in the side walls 12 c , 12d of the bracket 12 through a space between lateral webs of the bracket 12 , and a second end 20b supported by a further bolt 24 as a supporting element of the bracket 12 . The bolts 22 , 24 supporting the leaf spring 20 are secured by splints 26a, 26b .

[0047] In the embodiment of Figs . 1 - 4 , the leaf spring 20 is pre-bent with a convex surface facing the hydrogen tank 10 and supporting the tank 10 such that the leaf spring 20 is loaded when the tightening means 28 is tightened . Since the strap 14 extends via the rollers 16a , 16b through the openings 12 e , 12 f , a circumferential portion of the strap 14 is disposed beneath the leaf spring 20 . As long as the leaf spring 20 is not overloaded or bro ken, the hydrogen tank 10 entirely rests on the leaf spring 20 , i . e . the tens ioning force acting on the bracket 12 via the rollers 16a , 16b and the gravitational force is entirely supported by the leaf spring 20 , which is then deflected in response to the force , and not by other portions of the bracket 12 . The second end 20b of the leaf spring 20 can glide on the bolt 24 when the leaf spring 20 when the leaf spring is deflected, i . e . when its pre-bending is reduced .

[0048] Fig . 4 is a longitudinal view of the hydrogen tank 10 with the clamping structure of Fig . 1 . The bracket 12 includes at least one intermediate element 30 disposed between the bracket 12 and the tank . The intermediate element 30 includes a surface extension element 30a of a harder material , which provides bigger contact Surface between leaf spring 20 and tank, to reduce pressure generated on tank surface .

[0049] The intermediate element 30 of the bracket 12 further includes at least one interface element 30b disposed between the bracket 12 surface extension inlay and the tank . The interface element 30b is preferably made of EPDM rubber ( ethylene propylene diene monomer rubber ) , NBR (nitrile butadiene rubber ) or other polymer to protect the hydrogen tank 10 surface against damage and provide correct connection performance . The interface element 30b can provide additional compensation function due to its thickness and material parameters .

[0050] Figures 5 - 7 illustrate further embodiments of the invention . In order to avoid repetition, the following description of this further embodiment is essentially limited to differences from the first embodiment of the invention . Because of the unchanged features , the s killed person is referred to the des cription of the first embodiment . The same reference s igns are used for features of the further embodiments that have the same or s imilar effect in order to emphasize the similarities . Fig. 5 is a longitudinal view of a hydrogen tank 10 with a clamping structure according to a second embodiment of the invention .

[0051] The leaf spring 20 is pre-bent with a convex surface facing, downward, i.e. toward strap 14 and away from the hydrogen tank 10 and pushing the strap 14 outward in a portion between the rollers. The leaf spring 20 is loaded by the increased tension of the strap 14 when the tightening means 28 is tightened such that the strap 14 presses the convex portion of the leaf spring inward .

[0052] Figure 5 further illustrates an cut-out or opening 32 in the bracket 12 for visually confirming the status of the leaf spring 20.

[0053] In these embodiments, the leaf spring 20 is pre-bent with a convex surface facing downward, i.e. toward the strap 14 and away from the hydrogen tank 10, similar to the arrangement in Fig. 5. However, unlike the previous embodiments, the leaf spring 20 is supported on shoulder portions 34, 36 on both sides of the openings 12e, 12f of the bracket 12 in a form-fitting manner via teeth 38, 40. In one variant, the teeth 38, 40 are arranged immediately left and right of the strap 14, in the band area. In another variant, illustrated in Fig. 7, the teeth 42, 44 are positioned at the laterally outer ends of the bracket 12, separated from the band area.

[0054] In these embodiments, the leaf spring 20 does not require rollers 16a, 16b for guiding the strap 14 through the openings 12e, 12f. Furthermore, the leaf spring 20 has no journal bushing or bolt 22 as in the previous embodiments, but is instead directly secured to the bracket 12 via the form-fitting teeth 38, 40 or 42, 44. This arrangement provides a more compact design while maintaining the elastic compensation function.

[0055] Fig. 6 further illustrates an embodiment where the leaf spring 20 is formed as a multilayer leaf spring, comprising several layers 46a , 46b of spring material . The multilayer configuration allows for adj ustment of the spring characteristics by varying the number , thicknes s , and length of the individual spring layers . This provides flexibility in adapting the elastic compensation structure 18 to different tank sizes and pressure requirements . The layers may optionally be provided in different lengths and / or be arranged in a staggered configuration to provide a progres sive spring rate . In embodiments of the invention, the multilayer leaf spring is attached to the bracket 12 such that only one layer is directly connected to the teeth 38 , 40 , 42 , 44 , while the remaining layers are free to slide relative to the first layer during deflection . This combines two features ( teeth connection and multilayer spring ) in a specific configuration that optimizes the spring behavior .

[0056] The bracket 12 in the embodiments of Figs . 6 and 7 includes a rubber inlay 48 provided on the top surface of the bracket 12 , serving as an interface element between the bracket 12 and the hydrogen tank 10 . The rubber inlay 48 is preferably made of EPDM, NBR or other polymer to protect the hydrogen tank 10 surface against damage and provide correct connection performance , similar to the interface element 30b of the previous embodiments .

[0057] In operation , the leaf spring 20 deflects the strap 14 such that when the tightening means 28 is tightened , the tens ion in the strap 14 presses against the convex portion of the leaf spring 20 , loading it . As the hydrogen tank 10 expands during filling, the leaf spring 20 provides the necessary elastic compensation by flexing upward, thus maintaining proper tension in the strap 14 and secure holding of the tank 10 . The length variation resulting from the reduction or increase of the curvature can be accommodated by a sliding movement of the teeth 38 , 40 , 42 , 44 over the respective shoulder portions 42 , 44 .

[0058] The form-fitting connection via teeth 38 , 40 or 42 , 44 provides a more robust attachment of the leaf spring 20 to the bracket 12 , enhancing the long-term reliability of the clamping system while eliminating the need for additional fastening elements such as bolts and splints .

[0059] List of reference signs

[0060] 10 hydrogen tank

[0061] 12 bracket

[0062] 12a, 12b fastening tabs

[0063] 12c, 12d side walls

[0064] 12e, 12f openings

[0065] 14 strap

[0066] 14a, 14b loops

[0067] 14c metal band

[0068] 14d rubber inlay

[0069] 16a, 16b rollers

[0070] 18 elastic compensation structure

[0071] 20 leaf spring

[0072] 20a first end

[0073] 20b second end

[0074] 22 bolt

[0075] 24 bolt

[0076] 26a, 26b splint

[0077] 28 tightening means

[0078] 30 intermediate element

[0079] 30a surface extension element

[0080] 30b interface element

[0081] 32 opening

[0082] 34, 36 shoulder portions

[0083] 38, 40 teeth (near band area)

[0084] 42, 44 teeth (at laterally outer ends)

[0085] 46a, 46b individual spring layers

[0086] 48 rubber inlay (on bracket top surface)

Claims

Claims1. A clamping system for holding a cylindrical tank, comprising : a bracket (12) for supporting the cylindrical tank, a strap (14) for fastening the cylindrical tank on the bracket (12) , the strap (14) having a first end and a second end, tightening means (28) for connecting first end and the second end and being operable to increase or reduce the diameter encircled by the strap (14) , and an elastic compensation structure (18) capable of compensating for the predetermined length variations of the tensioning band corresponding to the cyclically varying dimensions of the tank, characterized in that the elastic compensation structure (18) includes a leaf spring (20) supported by the bracket (12) .

2. The clamping system according to claim 1, wherein the leaf spring (20) has a first end (20a) formed as a journal bushing being supported by a bolt 22 extending through a space between lateral webs of the bracket (12) , and a second end (20b) supported by an element of the bracket (12) .

3. The clamping system according to claim 1 or 2, wherein the leaf spring (20) is pre-bent with a convex surface configured to face the hydrogen tank (0) and to support the tank (10) such that the leaf spring (20) is loaded when the tightening means (28) is tightened, wherein the pre-bent configuration provides a predetermined spring force.

4. The clamping system according to claim 1 or 2, wherein the bracket (12) has first and second openings (12e, 12f) through which the strap (14) extends so that a circumferential portion of the strap (14) is disposed beneath the leaf spring (20) .

5. The clamping system according to claim 4, wherein the leaf spring (20) is pre-bent with a convex surface facing the strap (14) and deflecting the strap (14) such that the leaf spring (20) is loaded when the tightening means (28) is tightened .

6. The clamping system according to claim 4 or 5, wherein the bracket (12) includes rollers (16a, 16b) or bolts for guiding the strap (14) through the openings (12e, 12f) .

7. The clamping system according to one of the preceding claims, wherein the bracket (12) includes at least one interface element (30b) disposed between the bracket (12) and tank.

8. The clamping system according to one of the preceding claims, wherein the bracket (12) includes at least one opening for visually verifying a deflection status of the leaf spring (20) .

9. The clamping system according to one of the preceding claims, wherein the strap (14) includes a metal band (14c) with a rubber inlay ( 14d) .

10. The clamping system according to claim 1, wherein the leaf spring (20) is supported on shoulder portions (34, 36) on both sides of the openings (12e, 12f) of the bracket (12) in a form-fitting manner via teeth (38, 40, 42, 44) .

11. The clamping system according to claim 10, wherein the teeth (38, 40) are arranged immediately left and right of the strap (14) in the band area.

12. The clamping system according to claim 10, wherein the teeth (42, 44) are positioned at the laterally outer ends of the bracket (12) , separated from the band area.

13. The clamping system according to claim 1, wherein the leaf spring (20) is formed as a multilayer leaf spring comprising a plurality of layers (46a, 46b) of spring material.

14. The clamping system according to one of the preceding claims, wherein the leaf spring (20) is directly secured to the bracket (12) without rollers (16a, 16b) , journal bushings, or bolts (22, 24) .

15. The clamping system according to one of the preceding claims, wherein a rubber inlay (48) is provided on the top surface of the bracket (12) serving as an interface element between the bracket (12) and the tank (10) .

16. The clamping system according to claim 13, wherein the spring characteristics of the multilayer leaf spring (20) are adjustable by varying the number, thickness, and length of the individual spring layers (46a, 46b) .

17. The clamping system according to claim 1, wherein the bracket (12) includes visual indicators configured to show whether the leaf spring (20) is within its designed deflection range .

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