A vibration resistant fastener assembly

Abstract

The present invention relates to a vibration resistant fastener assembly (10) for mechanical connections. The assembly (10) may comprise a bolt (12) having a head (22) and a shank (24) with a plurality of helical grooves (26). The assembly (10) may further comprise a nut (16) having a plurality of internal helical grooves (42) complementary to the helical grooves (26) of the bolt (12). A resilient member (14) may be positioned between the nut (16) and the bolt (12). The resilient member (14) may comprise a plurality of helical coils (36) having a pitch matching the helical grooves (26) and the internal helical grooves (42). The resilient member (14) may be positioned simultaneously within both the helical grooves (26) and the internal helical grooves (42), thereby creating a mechanical connection between the bolt (12) and the nut (16).

Description

[0001] TITLE OF INVENTION:

[0002] A VIBRATION RESISTANT FASTENER ASSEMBLY

[0003] TECHNICAL FIELD

[0004]

[0001] The embodiments of the present disclosure generally relate to mechanical fasteners. In particular, the present disclosure relates to a vibration-resistant fastener assembly.

[0005] BACKGROUND

[0006] BACKGROUND OF THE INVENTION

[0007]

[0002] In the field of mechanical fasteners, nuts and bolts are among the most commonly used components for securing various structural elements together. Traditional threaded mechanical fasteners have been employed across numerous industries including automotive, aerospace, construction, and machinery manufacturing. The conventional mechanical fasteners typically consist of externally threaded bolts that engage with internally threaded nuts to create a secure mechanical connection.

[0008]

[0003] Conventional threaded fasteners, while widely used, face significant challenges when subjected to dynamic loading conditions. Vibration, shock, and thermal cycling frequently cause self-loosening of the threaded connections, resulting in potential failure of the assembly. This selfloosening phenomenon occurs as vibration causes relative movement between the threaded surfaces, gradually reducing the clamping force and allowing the fastener to rotate out of position. The problem is particularly acute in transportation equipment, machinery with reciprocating components, and structures exposed to environmental vibrations.

[0009]

[0004] Several solutions have been developed to address the self-loosening problem, including nylon insert lock nuts, deformed thread nuts, double nut arrangements, adhesive-based locking compounds, and specialized washers. However, these existing solutions present their own limitations. Nylon insert lock nuts and deformed thread nuts typically cannot be reused after removal. Double nut arrangements add weight and cost to the assembly. Adhesive-based locking solutions make disassembly difficult and often require specialized tools or heat application. Specialized washers, such as Nordlock washers, add cost and complexity to the fastening system.

[0010]

[0005] Another significant limitation of conventional threaded fasteners relates to material strength considerations. When using weaker or brittle materials such as aluminum, cast iron, or gun metal for nuts, traditional design principles require increasing the nut height proportionally to the bolt diameter to prevent thread stripping. For example, gun metal nuts typically require a height of 1.5 times the bolt diameter, cast iron nuts need 2.0 times the bolt diameter, and aluminum alloy nuts need 2.5 times the bolt diameter. These increased dimensions add unnecessary weight andspace requirements to the assembly, which is particularly problematic in weight-sensitive applications such as aerospace and automotive designs.

[0011]

[0006] Furthermore, conventional V-threads are often unsuitable for repeated assembly and disassembly when used with weaker or brittle materials. Thread damage frequently occurs during maintenance operations, necessitating the use of steel bushings or bronze inserts to reinforce the threaded portions. These inserts add manufacturing complexity, increase costs, and still do not fully address the vibration resistance problem.

[0012]

[0007] Additionally, conventional fastening systems that provide vibration resistance often involve complex mechanisms or additional components that increase the overall part count, leading to higher manufacturing costs, increased assembly time, and greater potential for component failure. The trade-off between securing against vibration and maintaining simple, lightweight designs represents a significant engineering challenge.

[0013]

[0008] Conventional fastener assemblies face difficulty in providing vibration resistance without increasing weight, maintaining thread integrity in weaker or brittle materials without additional reinforcements, and enabling repeated assembly and disassembly without thread damage. There is, therefore, a need in the art to provide a vibration-resistant fastener assembly that can overcome the shortcomings of the existing prior arts.

[0014] SUMMARY OF THE INVENTION

[0015]

[0009] This summary is provided to introduce the concepts related to a vibration-resistant fastener assembly; the concepts are further described in the detailed description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used in determining or limiting the scope of the present subject matter.

[0016]

[0010] In view of the above defects, the technical problem to be solved by the present invention is how to provide a vibration-resistant fastening assembly that prevents self-loosening under dynamic loading conditions without adding significant weight or requiring additional components. The technical problem further includes creating a fastening assembly that maintains thread integrity when using weaker or brittle materials such as aluminum, cast iron, or gun metal without requiring increased nut height or thread inserts, thereby reducing the overall weight of the fastening system while maintaining or improving mechanical strength.

[0017] [OH] In order to achieve the above object, the present invention provides a solution in the form of a vibration resistant fastener assembly. The vibration resistant fastener assembly comprises a bolt, a nut, and a resilient member positioned between the nut and the bolt. The bolt comprises a head and a shank. The shank comprises a plurality of helical grooves. The nut comprises a pluralityof internal helical grooves. The plurality of internal helical grooves is complementary to the plurality of helical grooves of the bolt. The resilient member comprises a plurality of helical coils. The plurality of helical coils comprises a pitch same as the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut. The resilient member is positioned within both the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut simultaneously, thereby creating a mechanical connection between the bolt and the nut.

[0018]

[0012] In some embodiments, the resilient member comprises a helical spring with the plurality of helical coils. The helical spring comprises a cross-section that varies along its length to create a differential spring rate for enhanced vibration resistance.

[0019]

[0013] In some embodiments, the helical spring comprises three portions: a top portion, a middle portion, and an end portion. The top portion constitutes 25% to 30% of the plurality of helical coils having a first wire diameter. The middle portion constitutes 40% to 50% of the plurality of helical coils extending from the top portion having a second wire diameter that is 10% to 15% smaller than the first wire diameter. The end portion constitutes 20% to 25% of the plurality of helical coils terminating at the free end having the same wire diameter as the top portion.

[0020]

[0014] In some embodiments, the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut each have a semicircular cross-section. The plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut align to form a continuous helical circular cavity when the bolt is inserted into the nut. The circular cavity receives the plurality of helical coils of the resilient member with a clearance fit.

[0021]

[0015] In some embodiments, the resilient member comprises a washer formed at a top coil of the resilient member. The washer comprises a plurality of positioning elements protruding from the washer. The nut includes a corresponding plurality of positioning grooves. When the plurality of positioning elements is inserted into the corresponding plurality of positioning grooves, the plurality of helical coils of the resilient member are aligned with the plurality of internal helical grooves of the nut for facilitating assembly of the fastener assembly.

[0022]

[0016] In some embodiments, the resilient member has a tapered bottom end configured to create a clamping force on the plurality of helical grooves of the bolt. The tapered bottom end has a taper ranging from 2mm to 4mm per 10mm of height.

[0023]

[0017] In some embodiments, the resilient member has a knurled surface texture on its outer surface. The knurled surface texture enhances frictional engagement simultaneously with both the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut, thereby increasing resistance to rotational movement between the bolt and the nut under vibration conditions.

[0018] In some embodiments, the resilient member is positioned within the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut such that when tensile load is applied between the bolt and the nut, shear forces are applied to the resilient member by the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut. The resilient member has a shear strength value greater than the maximum rated tensile load of the fastener assembly.

[0024]

[0019] In some embodiments, the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut have a pitch value that is at least 1.5 times greater than the standard pitch value of a conventional V-thread for a bolt of equivalent diameter. The nut has a height dimension equal to the nominal diameter of the bolt.

[0025]

[0020] In some embodiments, an end of the bolt comprises a first chamfered edge with a 45-degree chamfer angle. The resilient member comprises a washer at a top end having a second chamfered edge with a 45-degree chamfer angle. Each of the first chamfered edge and the second chamfered edge has a dimension equal to a radius of the resilient member. A bottom end of the nut comprises a third chamfered edge configured to accommodate a wrench. A bottom end of the resilient member is plain ground such that the bottom end remains within the nut when the bolt and the nut are assembled.

[0026]

[0021] The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.

[0027] BRIEF DESCRIPTION OF DRAWINGS

[0028]

[0022] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0029]

[0023] In the figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0030]

[0024] FIG. 1 illustrates a perspective view of a vibration-resistant fastener assembly in accordance with one embodiment of the present invention;

[0031]

[0025] FIG. 2 illustrates the perspective view of a bolt in accordance with one embodiment of the present invention;

[0026] FIG. 3A illustrates the perspective view of a resilient member accordance with one embodiment of the present invention;

[0032]

[0027] FIG. 3B illustrates the front view of a resilient member in accordance with one embodiment of the present invention; and

[0033]

[0028] FIG. 4A illustrates the perspective view of a nut in accordance with one embodiment of the present invention.

[0034]

[0029] FIG. 4B illustrates the front view of a nut in accordance with one embodiment of the present invention.

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036]

[0030] The following detailed description is susceptible to various modifications and alternative forms, specific embodiments thereof will be described in detail and shown by way of example. It should be understood, however, that there is no intent to limit example embodiments of the present invention to the particular forms disclosed. Conversely, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the invention.

[0037]

[0031] It should be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention.

[0038]

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the terms “comprises,” “comprising,” “includes,” “including,” and / or “having” specify the presence of stated features, integers, steps, operations, elements, and / or components when used herein, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039]

[0033] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. It should be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and are not to be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0040]

[0034] The present invention relates to a vibration resistant fastener assembly. The vibration resistant fastener assembly comprises a bolt, a nut, and a resilient member positioned between the nut and the bolt. The bolt comprises a head and a shank. The shank comprises a plurality of helicalgrooves. The nut comprises a plurality of internal helical grooves. The plurality of internal helical grooves is complementary to the plurality of helical grooves of the bolt. The resilient member comprises a plurality of helical coils. The plurality of helical coils comprises a pitch same as the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut. The resilient member is positioned within both the plurality of helical grooves of the bolt and the plurality of internal helical grooves of the nut simultaneously, thereby creating a mechanical connection between the bolt and the nut.

[0041]

[0035] The details of the invention are now described with reference to FIG. 1 to FIG. 4B.

[0042]

[0036] Referring to FIG. 1, a perspective view of a vibration-resistant fastener assembly 10 is illustrated in accordance with one embodiment of the present invention. The vibration-resistant fastener assembly 10 comprises three primary components: a bolt 12, a resilient member 14, and a nut 16. The three components work together to create a secure mechanical connection that resists loosening under vibration, shock, and thermal fluctuations. The vibration-resistant fastener assembly 10 provides superior fastening capabilities compared to conventional threaded fasteners.

[0043]

[0037] The bolt 12 serves as the male component of the vibration-resistant fastener assembly 10.

[0044] The bolt 12 differs from conventional bolts by featuring a plurality of helical grooves instead of standard threads. The bolt 12 may be manufactured from various materials including steel, stainless steel, aluminum, or other metals suitable for fastening applications. In some embodiments, the bolt 12 may be made from lightweight materials for applications where weight reduction is crucial, such as aerospace or automotive industries.

[0045]

[0038] The resilient member 14 is positioned between the bolt 12 and the nut 16. The resilient member 14 comprises a helical spring that fits within the grooves of both the bolt 12 and the nut 16. The resilient member 14 serves dual functions in the vibration-resistant fastener assembly 10.

[0046] First, the resilient member 14 creates a mechanical connection between the bolt 12 and the nut 16.

[0047] Second, the resilient member 14 provides a clamping force that prevents loosening under vibration. The resilient member 14 may be fabricated from high-strength materials with appropriate elasticity, such as spring steel or other resilient alloys.

[0048]

[0039] The nut 16 functions as the female component of the vibration-resistant fastener assembly 10. Like the bolt 12, the nut 16 features a plurality of internal helical grooves instead of conventional threads. The plurality of internal helical grooves of the nut 16 are complementary to the plurality of helical grooves of the bolt 12. The nut 16 may be manufactured from the same material as the bolt 12 or from different materials depending on the application requirements. The nut 16 may be hexagonal, square, or any other suitable shape for engagement with standard wrenches or tools.

[0040] The specific structural details and features of the bolt 12, the resilient member 14, and the nut 16 will be further described in subsequent figures. FIG. 2 will provide detailed views of the bolt 12. FIG. 3A and 3B will illustrate the structure of the resilient member 14. FIG. 4A and 4B will detail the configuration of the nut 16.

[0049]

[0041] Now, referring to the FIG. 2 the perspective view of a bolt is illustrated, in accordance with one embodiment of the present invention. The bolt 12 comprises a head 22 and a shank 24.

[0050] The head 22 is configured to receive torque from a wrench, socket, or other appropriate tool for installation and removal purposes. The head 22 may be hexagonal, square, or other polygonal shape in accordance with standard fastener designs. The head 22 provides a bearing surface that distributes clamping force across the fastened components.

[0051]

[0042] The shank 24 extends from the head 22 and forms the main body of the bolt 12. Unlike conventional bolts that utilize V-shaped threads, the shank 24 features a plurality of helical grooves 26 along its length. The plurality of helical grooves 26 have a semicircular cross-section that is designed to receive the coils of the resilient member 14 shown in FIG. 1. The plurality of helical grooves 26 may extend along the entire length of the shank 24 or may be present on only a portion of the shank 24, depending on the specific application requirements.

[0052]

[0043] The helical grooves 26 have a pitch that is at least 1.5 times greater than the standard pitch value of a conventional V-thread for a bolt of equivalent diameter. This increased pitch value contributes to the superior thread stripping strength of the vibration-resistant fastener assembly 10.

[0053] The semicircular cross-section of the helical grooves 26 forms one half of a circular cavity when aligned with the complementary internal helical grooves of the nut 16. For example, a standard M10 bolt typically has a pitch of 1.5mm, meaning the thread advances 1.5mm along the bolt axis per complete revolution.

[0054]

[0044] In the present invention, the helical grooves 26 of the bolt 12 feature a pitch value that is at least 1.5 times greater than standard values. Continuing with the M10 example, the helical grooves 26 would have a minimum pitch of 2.25mm (1.5 x 1.5mm). This increased pitch creates several advantages in the fastener assembly 10.

[0055]

[0045] First, the increased pitch results in fewer revolutions of helical grooves 26 for a given length of engagement between the bolt 12 and nut 16. This design distributes the applied load over a larger surface area per revolution, thereby reducing the stress concentration at any single point of the engagement surface. When a tensile load is applied to the fastener assembly 10, the force is distributed more evenly across the engaged portions of the helical grooves 26, the internal helical grooves 42 of the nut 16, and the resilient member 14.

[0056]

[0046] Second, the increased pitch significantly improves the thread stripping strength. Thread stripping occurs when excessive force causes the threads to deform and disengage, leading tofastener failure. The larger pitch creates a broader base for each helical groove, increasing the shear area that resists stripping forces. This enhanced resistance to stripping allows the nut 16 to maintain effective strength even when manufactured from weaker materials such as aluminum or brittle materials such as cast iron.

[0057]

[0047] The semicircular cross-section of the helical grooves 26 is another distinctive feature of the bolt 12. Unlike conventional V-shaped threads that create a wedging action, the semicircular profile of the helical grooves 26 is designed to accommodate the resilient member 14. When the bolt 12 is inserted into the nut 16, the semicircular helical grooves 26 of the bolt 12 align precisely with the complementary semicircular internal helical grooves 42 of the nut 16, creating a continuous helical circular cavity throughout the engaged length. This circular cavity provides an optimal housing for the plurality of helical coils 36 of the resilient member 14, ensuring consistent engagement and load distribution throughout the assembly.

[0058]

[0048] The resulting mechanical connection created by this arrangement transfers load through the resilient member 14 rather than through direct contact between the bolt 12 and nut 16, which is fundamentally different from conventional threaded fasteners. This load transfer mechanism enhances both the static strength and the dynamic vibration resistance of the fastener assembly 10.

[0059]

[0049] The end of the shank 24 includes a first chamfered edge 28 with a 45-degree chamfer angle. The first chamfered edge 28 has a dimension equal to the cross-sectional radius of the resilient member 14. This chamfered edge 28 serves to facilitate the initial engagement of the bolt 12 with the resilient member 14 during assembly, allowing the resilient member 14 to properly seat within the helical grooves 26 of the bolt 12. The chamfered edge 28 assists in guiding the resilient member 14 into the helical grooves 26 without causing damage to the resilient member 14

[0060]

[0050] The bolt 12 may be manufactured from various materials, including but not limited to mild steel, stainless steel, aluminum alloys, titanium, or other metals suitable for fastening applications. The selection of material for the bolt 12 depends on factors such as required strength, weight considerations, corrosion resistance, and compatibility with the fastened components. The helical grooves 26 may be formed through various manufacturing processes, including machining, rolling, or other appropriate metal forming techniques.

[0061]

[0051] Now referring to FIG. 3A and FIG. 3B, the perspective view and the front view of a resilient member is illustrated, in accordance with one embodiment of the present invention. FIG.

[0062] 3A illustrates a perspective view of the resilient member 14. The resilient member 14 comprises a washer 32 formed at the top end of the resilient member 14 and a plurality of helical coils 36 extending from the washer 32. The plurality of helical coils 36 have a specific pitch that exactly matches the pitch of the helical grooves 26 of the bolt 12 and the internal helical grooves 42 of thenut 16, enabling precise alignment during assembly. This matching pitch is critical for ensuring that the resilient member 14 can be simultaneously positioned within both the helical grooves 26 of the bolt 12 and the internal helical grooves 42 of the nut 16, thereby creating a secure mechanical connection between these components.

[0063]

[0052] The washer 32 includes a second chamfered edge 40 with a 45-degree chamfer angle. The dimension of the second chamfered edge 40 is equal to the cross-sectional radius of the resilient member 14. This chamfered edge 40 corresponds to and complements the first chamfered edge 28 of the bolt 12 as shown in FIG. 2, facilitating smooth insertion during assembly operations. For example, in automotive assembly lines where rapid installation is required, these complementary chamfered edges significantly reduce assembly time while ensuring proper component alignment.

[0064]

[0053] The bottom portion of the resilient member 14 terminates in a ground end 34. The ground end 34 is plain ground such that when the bolt 12 and the nut 16 are assembled, the ground end 34 remains within the nut 16. This design prevents the ground end 34 from protruding beyond the nut 16 after assembly, maintaining a clean and finished appearance of the fastener assembly 10.

[0065]

[0054] FIG. 3B provides a front view of the resilient member 14, clearly showing the structural elements of the resilient member 14. The resilient member 14 comprises a plurality of helical coils 36 that form the main body of the resilient member 14. The helical coils 36 have the same pitch as the helical grooves 26 of the bolt 12 and the internal helical grooves of the nut 16. This matching pitch ensures proper alignment and engagement of the resilient member 14 with both the bolt 12 and the nut 16.

[0066]

[0055] The resilient member 14 includes a plurality of positioning elements 38 that protrude from the washer 32. These positioning elements 38 are designed to engage with corresponding positioning grooves 46 in the nut 16. When the positioning elements 38 are inserted into the corresponding positioning grooves 46 of the nut 16, the helical coils 36 of the resilient member 14 align precisely with the internal helical grooves of the nut 16, facilitating proper assembly of the fastener assembly 10. When the positioning elements 38 are inserted into these positioning grooves 46, the plurality of helical coils 36 of the resilient member 14 are automatically aligned with the internal helical grooves 42 of the nut 16, significantly facilitating assembly of the fastener assembly 10. This alignment feature is particularly valuable in low-visibility installation environments, such as automotive underbody assembly, where direct visual confirmation of proper alignment is difficult or impossible.

[0067]

[0056] The resilient member 14 may have a cross-section that varies along its length to create a differential spring rate for enhanced vibration resistance. For instance, in applications such as railway fasteners subjected to both low-frequency (1-5 Hz) vibrations from track irregularities and high-frequency (50-200 Hz) vibrations from wheel-rail interactions, the differential spring rateenables effective damping across this broad frequency spectrum. In specific embodiments, the helical spring of the resilient member 14 comprises three distinct portions with specific design parameters. The top portion constitutes 25% to 30% of the total coils 36 and features a first wire diameter. In a typical M12 fastener implementation, this first wire diameter might be 2.4mm. The middle portion constitutes 40% to 50% of the coils 36 extending from the top portion and has a second wire diameter that is 10% to 15% smaller than the first diameter (approximately 2.0-2.2mm in the M12 example). The end portion constitutes the remaining 20% to 25% of the 36 coils terminating at the free end and returns to the same wire diameter as the top portion. This three-zone design optimizes both vibration damping and load distribution capabilities.

[0068]

[0057] The resilient member 14 has a tapered bottom end configured to create a clamping force on the helical grooves 26 of the bolt 12. The tapered bottom end has a taper ranging from 2mm to 4mm per 10mm of height. This tapering design enhances the vibration resistance of the fastener assembly 10 by creating additional frictional engagement with the bolt 12.

[0069]

[0058] The outer surface of the resilient member 14 features a knurled surface texture. This knurled surface texture enhances frictional engagement simultaneously with both the helical grooves 26 of the bolt 12 and the internal helical grooves of the nut 16. The increased friction resulting from the knurled surface texture increases resistance to rotational movement between the bolt 12 and the nut 16 under vibration conditions.

[0070]

[0059] The resilient member 14 is manufactured from high-strength materials with appropriate shear strength properties. When tensile load is applied between the bolt 12 and the nut 16, shear forces are applied to the resilient member 14 by the helical grooves 26 of the bolt 12 and the internal helical grooves of the nut 16. The resilient member 14 has a shear strength value greater than the maximum rated tensile load of the fastener assembly 10, ensuring that the mechanical connection remains intact under maximum loading conditions.

[0071]

[0060] In alternative embodiments, the resilient member 14 may be manufactured from various high-strength materials including, but not limited to, spring steel, stainless steel alloys, titanium alloys, or specialized copper-beryllium alloys for applications requiring electrical conductivity along with mechanical fastening. The selection of material depends on specific application requirements such as operating temperature range, corrosion resistance needs, and electrical properties.

[0072]

[0061] Now referring to FIG. 4A and FIG. 4B, the perspective view and front view of a nut is illustrated, in accordance with one embodiment of the present invention. The nut 16 comprises a plurality of internal helical grooves 42 that are complementary to the helical grooves 26 of the bolt 12 shown in FIG. 2. The internal helical grooves 42 have a semicircular cross-section that corresponds to the semicircular cross-section of the helical grooves 26 of the bolt 12. When thebolt 12 is inserted into the nut 16, the helical grooves 26 of the bolt 12 and the internal helical grooves 42 of the nut 16 align to form a continuous helical circular cavity. This circular cavity receives the helical coils 36 of the resilient member 14 with a clearance fit.

[0073]

[0062] The internal helical grooves 42 have the same pitch as the helical grooves 26 of the bolt 12 and the helical coils 36 of the resilient member 14. The pitch value of the internal helical grooves 42 is at least 1.5 times greater than the standard pitch value of a conventional V-thread for a bolt of equivalent diameter. This increased pitch contributes to the enhanced thread stripping strength of the vibration-resistant fastener assembly 10.

[0074]

[0063] The nut 16 includes a bottom end with a third chamfered edge 44 configured to accommodate a wrench or other installation tool. The chamfered edge 44 facilitates easier engagement with the installation tool and reduces the risk of damage to the nut 16 during installation or removal operations. The external shape of the nut 16 may be hexagonal, square, or any other polygonal shape suitable for engagement with standard wrenches or tools.

[0075]

[0064] The nut 16 has a height dimension equal to the nominal diameter of the bolt 12. This height-to-diameter ratio is significantly lower than traditional nuts made from weaker or brittle materials, which typically require heights of 1.5 to 2.5 times the bolt diameter to prevent thread stripping. The reduced height-to-diameter ratio is made possible by the increased thread stripping strength provided by the combination of the helical grooves 26, internal helical grooves 42, and the resilient member 14.

[0076]

[0065] The nut 16 includes a plurality of positioning grooves 46 that correspond to the positioning elements 38 of the resilient member 14 shown in FIG. 3B. These positioning grooves 46 ensure proper alignment of the resilient member 14 with the internal helical grooves 42 of the nut 16 during assembly. When the positioning elements 38 of the resilient member 14 are inserted into the positioning grooves 46 of the nut 16, the helical coils 36 of the resilient member 14 align precisely with the internal helical grooves 42 of the nut 16.

[0077]

[0066] The nut 16 may be manufactured from various materials, including but not limited to steel, stainless steel, aluminum, cast iron, gun metal, or other metals suitable for fastening applications. The design of the vibration-resistant fastener assembly 10 allows the use of weaker or brittle materials for the nut 16 without requiring additional height or thread inserts, resulting in significant weight savings compared to conventional fasteners while maintaining structural integrity.

[0078]

[0067] During assembly of the vibration resistant fastener assembly 10, the positioning elements 38 of the resilient member 14 engage with corresponding positioning grooves in the nut 16. This engagement ensures proper alignment of the helical coils 36 with the internal helical grooves 42 of the nut 16. The chamfered edges of both the bolt 12 and the resilient member 14 facilitate smooth initial engagement.

[0068] When the bolt 12 is inserted through the aligned resilient member 14 and nut 16, the helical coils 36 of the resilient member 14 simultaneously engage with both the helical grooves 26 of the bolt 12 and the internal helical grooves 42 of the nut 16. This simultaneous engagement creates a secure mechanical connection between the bolt 12 and the nut 16.

[0079]

[0069] The knurled surface texture on the outer surface of the resilient member 14 increases frictional engagement with both the bolt 12 and the nut 16. This increased friction significantly enhances resistance to rotational movement between components under vibration conditions. For example, in applications such as railway track fasteners or heavy machinery mounts, where continuous vibration occurs, this feature prevents gradual loosening that commonly affects conventional fasteners.

[0080]

[0070] When tensile load is applied to the fastener assembly 10, shear forces are distributed to the resilient member 14 through its engagement with both the bolt 12 and the nut 16. The resilient member 14 is designed with a shear strength value exceeding the maximum rated tensile load of the fastener assembly 10. For instance, if the maximum rated tensile load is 10,000 N, the resilient member 14 would have a shear strength value greater than 10,000 N to ensure structural integrity under all loading conditions.

[0081]

[0071] The vibration resistant fastener assembly 10 offers several significant advantages over conventional threaded fasteners. First, it prevents self-loosening without additional locking components. Second, it allows the use of weaker or brittle materials for the nut 16 without requiring increased height or thread inserts, resulting in substantial weight savings. Third, the assembly can be disassembled and reassembled multiple times without degradation of performance.

[0082]

[0072] The higher pitch value of the helical grooves enables faster assembly and disassembly, reducing installation time in manufacturing and maintenance operations. For instance, a conventional bolt might require six complete rotations for full engagement, while the vibration resistant fastener assembly 10 with 1.5 times greater pitch would require only four rotations to achieve the same engagement length.

[0083]

[0073] The clearance fit between the circular cavity formed by the aligned grooves and the coils of the resilient member 14 allows for thermal expansion without inducing additional stress in the assembly. This feature is particularly advantageous in applications experiencing temperature fluctuations, such as automotive engine components or outdoor infrastructure.

[0084]

[0074] The resilient member 14 with its tapered bottom end creates a clamping force ranging from 2mm to 4mm per 10mm of height. This tapering design enhances vibration resistance by increasing friction between components. The specific taper value can be selected based onapplication requirements - with greater taper providing stronger vibration resistance at the cost of increased assembly torque.

[0085]

[0075] The plain ground bottom end 34 of the resilient member 14 ensures that no portion protrudes beyond the nut 16 when assembled, resulting in a clean, flush installation. This feature is particularly important in applications where protruding components could cause interference or safety hazards.

[0086]

[0076] In the above description, numerous specific details are set forth such as examples of some embodiments, specific components, devices, methods, in order to provide a thorough understanding of embodiments of the present subject matter. It will be apparent to a person of ordinary skill in the art that these specific details need not be employed and should not be construed to limit the scope of the subject matter.

[0087]

[0077] In the development of any actual implementation, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints. Such a development effort might be complex and time consuming, but may nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill. Hence, as various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

[0088]

[0078] The foregoing description of embodiments is provided to enable any person skilled in the art to make and use the subject matter of the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the novel principles and subject matter disclosed herein may be applied to other embodiments without the use of the innovative faculty. It is contemplated that additional embodiments are within the true scope of the disclosed subject matter.

[0089] TECHNICAL ADVANTAGES

[0090]

[0079] The present disclosure provides a vibration resistant fastener assembly that prevents selfloosening under vibration, shock, and thermal cycling conditions through a tapered helical spring mechanism that maintains consistent clamping force throughout the fastener's service life.

[0091]

[0080] The present disclosure enables the use of weaker or brittle materials (aluminum, cast iron, gun metal) for nuts without requiring increased nut height or thread inserts, as the higher pitch semicircular grooves and spring mechanism distribute load more evenly, resulting in weight reduction of 30-50% compared to conventional fasteners.

[0092]

[0081] The present disclosure achieves superior thread stripping strength through the combination of semicircular helical grooves with a pitch value at least 1.5 times greater thanstandard thread pitch, allowing the nut height to equal the nominal bolt diameter regardless of material choice.

[0093]

[0082] The present disclosure permits repeated assembly and disassembly without thread damage due to the resilient member acting as an intermediary between bolt and nut grooves, eliminating direct metal-to-metal contact that causes thread degradation in conventional fasteners.

[0094]

[0083] The present disclosure reduces installation and removal time by requiring fewer rotations for complete engagement due to the higher pitch value, while the positioning elements and corresponding grooves ensure precise alignment during assembly operations.

Claims

I / WE CLAIM:

1. A vibration resistant fastener assembly (10), wherein the vibration resistant fastener assembly (10) comprises:a bolt (12), wherein the bolt (12) comprises a head (22) and a shank (24), wherein the shank (24) comprises a plurality of helical grooves (26);a nut (16), wherein the nut (16) comprises a plurality of internal helical grooves (42), wherein the plurality of internal helical grooves (42) is complementary to the plurality of helical grooves (26) of the bolt (12); anda resilient member (14) positioned between the nut (16) and the bolt (12); wherein the resilient member (14) comprises a plurality of helical coils (36), wherein the plurality of helical coils (36) comprises a pitch same as the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16), wherein the resilient member (14) is positioned within both the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16) simultaneously, thereby creating a mechanical connection between the bolt (12) and the nut (16).

2. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the resilient member (14) comprises a helical spring with the plurality of helical coils (36), wherein the helical spring comprises a cross-section that varies along its length to create a differential spring rate for enhanced vibration resistance.

3. The vibration resistant fastener assembly (10) as claimed in claim 2, wherein the helical spring comprises three portions: a top portion, a middle portion, and an end portion, wherein the top portion constitutes 25% to 30% of the plurality of helical coils (36) having a first wire diameter, wherein the middle portion constitutes 40% to 50% of the plurality of helical coils (36) extending from the top portion having a second wire diameter that is 10% to 15% smaller than the first wire diameter, and wherein the end portion constitutes 20% to 25% of the plurality of helical coils (36) terminating at the free end having the same wire diameter as the top portion.

4. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16) each have a semicircular cross-section, wherein the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16) align to form a continuous helical circular cavity when the bolt (12) is inserted into the nut (16), and wherein the circular cavity receives the plurality of helical coils (36) of the resilient member (14) with a clearance fit.

5. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the resilient member (14) comprises a washer (32) formed at a top coil of the resilient member (14), wherein the washer (32) comprises a plurality of positioning elements (38) protruding from the washer (32), wherein the nut (16) includes a corresponding plurality of positioning grooves (46), and wherein when the plurality of positioning elements (38) are inserted into the corresponding plurality of positioning grooves (46), the plurality of helical coils (36) of the resilient member (14) are aligned with the plurality of internal helical grooves (42) of the nut (16) for facilitating assembly of the fastener assembly (10).

6. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the resilient member (14) has a tapered bottom end configured to create a clamping force on the plurality of helical grooves (26) of the bolt (12), and wherein the tapered bottom end has a taper ranging from 2mm to 4mm per 10mm of height.

7. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the resilient member (14) has a knurled surface texture on its outer surface, wherein the knurled surface texture enhances frictional engagement simultaneously with both the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16), thereby increasing resistance to rotational movement between the bolt (12) and the nut (16) under vibration conditions.

8. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the resilient member (14) is positioned within the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16) such that when tensile load is applied between the bolt (12) and the nut (16), shear forces are applied to the resilient member (14) by the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16), and wherein the resilient member (14) has a shear strength value greater than the maximum rated tensile load of the fastener assembly (10)9. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein the plurality of helical grooves (26) of the bolt (12) and the plurality of internal helical grooves (42) of the nut (16) have a pitch value that is at least 1.5 times greater than the standard pitch value of a conventional V-thread for a bolt of equivalent diameter, and wherein the nut (16) has a height dimension equal to the nominal diameter of the bolt (12).

10. The vibration resistant fastener assembly (10) as claimed in claim 1, wherein an end of the bolt (12) comprises a first chamfered edge (28) with a 45-degree chamfer angle, wherein the resilient member (14) comprises a washer (32) at a top end having a second chamfered edge (40) with a 45-degree chamfer angle, wherein each of the first chamfered edge (28)and the second chamfered edge (40) has a dimension equal to a cross-sectional radius of the resilient member (14), wherein a bottom end of the nut (16) comprises a third chamfered edge (44) configured to accommodate a wrench, and wherein a bottom end (34) of the resilient member (14) is plain ground such that the bottom end (34) remains within the nut (16) when the bolt (12) and the nut (16) are assembled.

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