Elastic compression spring with load tuning feature and related tuning method

Abstract

Elastic compression springs with load tuning features and related tuning methods are disclosed, providing an elastic compression spring for isolating vibrations between a first part and a second part. The first part is movable in a direction relative to the second part. The elastic compression spring includes a tube elongated along a central axis of the tube. The central axis of the tube is perpendicular to the direction. The tube is configured to compress in the direction. The tube includes an outer surface that includes an initial contact line configured to initially receive contact with the first part. The tube further includes at least one load tuning feature in the outer surface, parallel to the central axis, and circumferentially spaced from the initial contact line. The at least one load tuning feature causes a local change in a thickness of the tube and a stiffness of the elastic compression spring at the at least one load tuning feature.

Description

[0001] This application is a divisional application of Chinese patent application 201910584103.X, filed on July 1, 2019, entitled "Elastic Compression Spring with Load Tuning Features and Related Tuning Method". Technical Field

[0002] This disclosure relates generally to vibration isolators, and more particularly to elastic compression springs. Background Technology

[0003] In some applications, elastic compression springs are used to isolate vibrations. Such elastic compression springs are configured to isolate vibrations based on their load-displacement properties and frequency response. Manufacturing an elastic compression spring that achieves specific load-displacement properties without requiring excessive trial-and-error iterations can be difficult. Summary of the Invention

[0004] The subject matter of this application was developed in response to the shortcomings of the prior art, particularly those of elastic compression springs and related manufacturing methods, which have not been fully resolved by currently available technology. Therefore, the subject matter of this application has been developed to provide examples of elastic compression springs and related methods for manufacturing elastic compression springs that overcome at least some of the aforementioned shortcomings in the prior art.

[0005] This document discloses an elastic compression spring for isolating vibrations between a first part and a second part. The first part is movable in a direction relative to the second part. The elastic compression spring includes a conduit extending along a central axis perpendicular to this direction. The conduit is configured to compress in this direction. The conduit includes an outer surface including an initial contact line configured to initially receive contact with the first part. The conduit further includes at least one groove formed in the outer surface, parallel to the central axis and circumferentially spaced from the initial contact line. The at least one groove causes a local reduction in the thickness of the conduit and the stiffness of the elastic compression spring. The foregoing subject of this paragraph describes Example 1 of this disclosure.

[0006] The conduit further includes two grooves formed in the outer surface of the conduit on opposite sides of the initial contact line. The foregoing subject matter of this paragraph describes Example 2 of this disclosure, wherein Example 2 also includes the subject matter according to Example 1 described above.

[0007] The two grooves are circumferentially spaced equidistant from the initial contact line. The foregoing subject matter of this paragraph describes Example 3 of this disclosure, which also includes the subject matter according to Example 2 above.

[0008] The conduit further includes four grooves formed in the outer surface of the conduit. Two of the four grooves are located on the side of the initial contact line opposite to the other two of the four grooves. The foregoing subject matter of this paragraph describes Example 4 of this disclosure, wherein Example 4 also includes the subject matter according to any one of Example 2 or Example 3 described above.

[0009] The outer surface of the pipe has a curved convex shape. At least one groove has a curved concave shape. The foregoing subject matter of this paragraph describes Example 5 of this disclosure, wherein Example 5 also includes the subject matter according to any one of Examples 1-4 above.

[0010] The pipe is made of thermoplastic elastomer. The foregoing subject matter of this paragraph describes Example 6 of this disclosure, wherein Example 6 also includes the subject matter according to any one of Examples 1-5 above.

[0011] As the pipe moves circumferentially toward the initial contact line, the thickness of the pipe decreases and increases along at least one groove. The foregoing subject matter of this paragraph describes Example 7 of this disclosure, which also includes the subject matter according to any one of Examples 1-6 above.

[0012] The depth of at least one groove corresponds to the decrease in the load-displacement ratio of the elastic compression spring. The length of at least one groove corresponds to the displacement range of the pipe during which the load-displacement ratio decreases. The circumferential distance of at least one groove from the initial contact line corresponds to the displacement of the pipe at which the load-displacement ratio of the elastic compression spring begins to decrease. The foregoing subject matter of this paragraph describes Example 8 of this disclosure, wherein Example 8 also includes the subject matter according to any one of Examples 1-7 above.

[0013] This document also discloses an elastic compression spring for isolating vibrations between a first part and a second part. The first part is movable in a direction relative to the second part. The elastic compression spring includes a conduit extending along a central axis perpendicular to that direction. The conduit is configured to compress in that direction. The conduit includes an outer surface including an initial contact line configured to initially receive contact with the first part. The conduit further includes at least one rib formed in the outer surface, parallel to the central axis and circumferentially spaced from the initial contact line. The at least one rib causes a local increase in the thickness of the conduit and the stiffness of the elastic compression spring. The foregoing subject of this paragraph describes Example 9 of this disclosure.

[0014] The conduit further includes two ribs formed in the outer surface of the conduit on opposite sides of the initial contact line. The foregoing subject matter of this paragraph describes Example 10 of this disclosure, wherein Example 10 also includes the subject matter according to Example 9 described above.

[0015] The two ribs are circumferentially separated by the same distance from the initial contact line. The foregoing subject matter of this paragraph describes Example 11 of this disclosure, wherein Example 11 also includes the subject matter according to Example 10 above.

[0016] The conduit further includes four ribs formed in the outer surface of the conduit. Two of the four ribs are located on the side of the initial contact line opposite to the other two of the four ribs. The foregoing subject matter of this paragraph describes Example 12 of this disclosure, wherein Example 12 also includes the subject matter according to any one of Examples 10 or 11 described above.

[0017] The outer surface of the pipe has a curved convex shape. At least one rib has a curved convex shape with a radius of curvature smaller than the radius of curvature of the curved convex shape of the outer surface of the pipe. The foregoing subject matter of this paragraph describes Example 13 of this disclosure, wherein Example 13 also includes the subject matter according to any one of Examples 9-12 above.

[0018] The pipe is made of thermoplastic elastomer. The foregoing subject matter of this paragraph describes Example 14 of this disclosure, wherein Example 14 also includes the subject matter according to any one of Examples 9-13 above.

[0019] As the pipe moves circumferentially toward the initial contact line, the thickness of the pipe increases and decreases along at least one rib. The foregoing subject matter of this paragraph describes Example 15 of this disclosure, which also includes the subject matter according to any one of Examples 9-14 above.

[0020] The height of at least one rib corresponds to the magnitude of the increment in the load-displacement ratio of the elastic compression spring. The length of at least one rib corresponds to the displacement range of the pipe during which the load-displacement ratio increases. The circumferential distance of at least one rib from the initial contact line corresponds to the displacement of the pipe at which the load-displacement ratio of the elastic compression spring begins to increase. The foregoing subject matter of this paragraph describes Example 16 of this disclosure, wherein Example 16 also includes the subject matter according to any one of Examples 9-15 above.

[0021] This document also discloses a method for tuning an elastic compression spring. The method includes identifying at least one difference between a desired load-displacement performance and an actual load-displacement performance of the elastic compression spring. The method further includes determining a desired local reduction in the load-displacement ratio that begins at a desired first displacement and ends at a desired second displacement and corresponds to at least one difference between the desired load-displacement performance and the actual load-displacement performance. The method further includes updating at least one groove formed in the outer surface of a conduit of the elastic compression spring according to the desired local reduction in the load-displacement ratio to achieve the desired load-displacement performance. The foregoing subject matter of this paragraph describes Example 17 of this disclosure.

[0022] The elastic compression spring is updated such that the depth of at least one groove corresponds to the magnitude of the desired local reduction in the load-displacement ratio, the circumferential distance of at least one groove from the initial contact line of the pipe corresponds to the desired first displacement, and the length of at least one groove corresponds to the desired second displacement. The foregoing subject matter of this paragraph describes Example 18 of this disclosure, wherein Example 18 also includes the subject matter according to Example 17 described above.

[0023] This document also discloses a method for tuning an elastic compression spring. The method includes identifying at least one difference between a desired load-displacement performance and an actual load-displacement performance of the elastic compression spring. The method further includes determining a desired local increase in the load-displacement ratio that begins at a desired first displacement and ends at a desired second displacement and corresponds to at least one difference between the desired load-displacement performance and the actual load-displacement performance. The method further includes updating at least one rib formed in the outer surface of a conduit of the elastic compression spring according to the desired local increase in the load-displacement ratio to achieve the desired load-displacement performance. The foregoing subject matter of this paragraph describes Example 19 of this disclosure.

[0024] The elastic compression spring is updated such that the height of at least one rib corresponds to the magnitude of the desired local increase in the load-displacement ratio, the circumferential distance of at least one rib from the initial contact line of the pipe corresponds to the desired first displacement, and the length of at least one rib corresponds to the desired second displacement. The foregoing subject matter of this paragraph describes Example 20 of this disclosure, wherein Example 20 also includes the subject matter according to Example 19 described above.

[0025] In one or more examples and / or embodiments, the features, structures, advantages, and / or characteristics of the subject matter of this disclosure described herein can be combined in any suitable manner. Numerous specific details are provided in the following description to provide a thorough understanding of the subject matter of this disclosure. Those skilled in the art will recognize that the subject matter of this disclosure can be practiced without specific features, details, components, materials, and / or methods of specific examples or embodiments. In other instances, additional features and advantages may be identified in certain examples and / or embodiments that may not be present in all examples or embodiments. Furthermore, in some instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the subject matter of this disclosure. The features and advantages of the subject matter of this disclosure will become more apparent from the following description and the appended claims, or may be learned by practicing the subject matter described below. Attached Figure Description

[0026] To more readily understand the advantages of the subject matter, a more specific description of the subject matter briefly described above will be presented with reference to specific examples shown in the accompanying drawings. It should be understood that these drawings depict only typical examples of the subject matter and are therefore not intended to limit its scope. Additional characteristics and details of the subject matter will be described and explained using the drawings, in which: Figure 1 This is a perspective view of an elastic compression spring according to one or more examples of this disclosure; Figure 2 It is according to one or more examples of this disclosure between two parts Figure 1 A front view of an elastic compression spring; Figure 3 It is illustrated according to one or more examples of this disclosure as compression between two parts. Figure 1 A front view of an elastic compression spring; Figure 4 It is illustrated according to one or more examples of this disclosure as compression between two parts. Figure 1 A front view of an elastic compression spring; Figure 5 This is a front view of an elastic compression spring between two parts according to one or more examples of this disclosure; Figure 6 It is illustrated according to one or more examples of this disclosure as compression between two parts. Figure 5 A front view of an elastic compression spring; Figure 7 It is illustrated according to one or more examples of this disclosure as compression between two parts. Figure 5 A front view of an elastic compression spring; Figure 8 This is a perspective view of an elastic compression spring according to one or more examples of this disclosure; Figure 9 It is according to one or more examples of this disclosure between two parts Figure 8 A front view of an elastic compression spring; Figure 10 This illustrates one or more examples according to this disclosure. Figure 1 A graph showing the load-displacement properties of an elastic compression spring; Figure 11 This illustrates one or more examples according to this disclosure. Figure 5 A graph showing the load-displacement properties of an elastic compression spring; Figure 12 This illustrates one or more examples according to this disclosure. Figure 8 A graph showing the load-displacement properties of an elastic compression spring; and Figure 13This is a schematic flowchart of a tuning method for an elastic compression spring according to one or more examples of this disclosure. Detailed Implementation

[0027] Throughout this specification, references to “an example,” “example,” or similar language mean that at least one example of this disclosure includes a particular feature, structure, or characteristic described in connection with that example. Throughout this specification, the phrases “in an example,” “in the example,” and similar language may, but not necessarily all, refer to the same example. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more examples of this disclosure; however, unless there is an explicit relevance to indicate otherwise, an implementation may be associated with one or more examples.

[0028] Reference Figure 1 and Figure 2 The diagram illustrates an example of a resilient compression spring 110. The resilient compression spring 110 is configured to isolate vibrations between a first part 102 and a second part 104 (see, for example...). Figure 2 As defined herein, vibration is defined as relative motion between two parts. The first part 102 is movable relative to the second part 104 in direction 106. In some embodiments, the motion of the first part 102 relative to the second part 104 (also defined as the motion of the second part 104 relative to the first part 102) can be an intentional or controlled motion, such as the opening and closing of a door relative to a frame. However, in other embodiments, the motion of the first part 102 relative to the second part 104 can be unintentional or uncontrolled, such as vibration between the engine and the frame caused by normal engine operation. A resilient compression spring 110 isolates the vibration or relative motion between the first part 102 and the second part 104. Furthermore, the vibration isolation characteristics of the resilient compression spring 110 are tunable (e.g., customizable) to predictably achieve desired load-displacement and / or frequency performance based on the intended use of the resilient compression spring 110.

[0029] The resilient compression spring 110 includes a base 114 and a conduit 112 coupled to the base 114. The base 114 provides a platform supporting the conduit 112. Typically, the base 114 is configured to securely engage a second part 104 such that the conduit 112 is securely engaged with the second part 104 and inserted between the first part 102 and the second part 104. The base 114 can be securely engaged with the second part 104 in various ways. For example, the base 114 can be adhered, bonded, fastened, interference-fitted, and / or interlocked with the second part 104. The base 114 may have engagement surfaces configured to complementaryly engage corresponding surfaces of the second part 104. In the illustrated example, the base 114 has a flat surface that engages the flat surface of the second part 104. Although the base 114 can have any of the various shapes and sizes that enable anchoring of the pipe 112 relative to the second part 104, in the illustrated example, the base 114 has a thin-walled rectangular shape and a footprint larger than that of the pipe 112. In some examples, the resilient compression spring 110 is not included in the base 114 (e.g., the pipe 112 may be attached to the second part 104 in that direction).

[0030] A conduit 112 protrudes from a base 114 such that when the base 114 engages with the second part 104, the conduit 112 is inserted between the base 114 and the first part 102. Typically, the conduit 112 is defined as a circumferentially closed sidewall. The conduit 112 defines a central axis 122 along which it extends. In some examples, the central axis 122 is the geometric center of the conduit 112. As defined herein, the conduit 112 is hollow, which facilitates compression of the conduit 112. Therefore, the conduit 112 includes a hollow internal channel 119 that extends the length of the conduit 112 along the central axis 122. The conduit 112 includes an inner surface 116 and an outer surface 117. The inner surface 116 faces the central axis 122, while the outer surface 117 is away from the central axis 122. Accordingly, the inner surface 116 is concave, while the outer surface 117 is convex. The inner surface 116 defines the hollow internal channel 119.

[0031] Although the pipe 112 in the illustrated example is a hollow, elongated pipe, in other examples, pipe 112 may have a hollow sphere shape. The hollow spherical pipe may have the same cross-sectional shape as the hollow, elongated pipe. However, the cross-sectional shape of the hollow spherical pipe will be rotated 360 degrees, rather than linearly along the axis. As described below, one or more grooves 120 or ribs 150 will extend circumferentially around the hollow spherical shape, either continuously or discontinuously.

[0032] The conduit 112 has a thickness (T) defined as the minimum distance between the inner surface 116 and the outer surface 117 at any point around the conduit 112. In some examples, the thickness (T) is more specifically defined as the distance between the inner surface 116 and the outer surface 117 in a direction radially away from the central axis 122. The thickness (T) of the conduit 112 can vary at different locations along the circumference of the conduit 112. In other words, the thickness (T) of the conduit 112 can change as it is moved in the circumferential direction along the conduit 112.

[0033] The thickness (T) of pipe 112 is related to its stiffness. In other words, for a given material, the thicker pipe 112 is, the stiffer it is. Furthermore, the stiffness of pipe 112 affects vibration isolation characteristics. More specifically, the stiffness of pipe 112 affects the load-displacement performance of elastic compression spring 110. For example, the stiffer pipe 112 is, the higher the load on elastic compression spring 110 for a given displacement. Conversely, the more elastic pipe 112 is, the lower the load on elastic compression spring 110 for a given displacement. Therefore, the load-displacement performance of elastic compression spring 110 is a measure of the compressive resistance (e.g., load) generated by elastic compression spring 110 for a given compressive displacement (e.g., compression).

[0034] Typically, when the elastic compression spring 110 is compressed, the compressive resistance or load generated by the elastic compression spring 110 increases. In some examples, as the elastic compression spring 110 is further compressed, the load-displacement ratio (e.g., the rate at which the load on the elastic compression spring 110 changes as the elastic compression spring 110 is compressed) also increases. See references respectively. Figure 10 Chart 170 and Figure 11 Figure 180, according to one example, shows the load-displacement ratio, represented by a load-displacement curve 172 for an elastic compression spring 110 without grooves 120, which continuously increases with continuous compression displacement. Therefore, the load-displacement curve 172 is non-linear or curvilinear. In some embodiments, the load-displacement curve 172 is considered a fully exponential curve, or the load and displacement of the elastic compression spring 110 without grooves 120 are completely exponentially related.

[0035] In some applications, it may be desirable for the elastic compression spring to have a discontinuously increasing load-displacement ratio. For example, in some cases, it may be desirable for the elastic compression spring to have a load-displacement ratio that decreases over a desired displacement range. In other words, it may be desirable for the elastic compression spring to have a load and displacement that are only partially exponentially related. To facilitate a reduction in the load-displacement ratio over a desired displacement range, the conduit 112 of the elastic compression spring 110 includes at least one groove 120 formed in the outer surface 117 of the conduit 112. As will be described in more detail, the groove 120 causes a local reduction in the thickness (T) of the conduit 112, which results in a local reduction in the stiffness of the elastic compression spring 110 at the groove 120.

[0036] The conduit 112 further includes an initial contact line 136, which is a hypothetical or imaginary line. The initial contact line 136 represents the portion of the outer surface 117 that initially contacts the first part 102 when the first part 102 moves toward the second part 104 in direction 106. Therefore, the elastic compression spring 110 is fixedly coupled to the second part 104 and oriented such that the initial contact line 136 initially receives the first part 102. In some embodiments, movement of the first part 102 relative to the second part 104 begins when the first part 102 contacts the initial contact line 136 of the conduit 112. In other embodiments, the first part 102 is moved to contact the initial contact line 136 of the conduit 112. A groove 120 is formed in the outer surface 117 of the conduit 112 at a circumferentially spaced distance from the initial contact line 136. As defined herein, circumferential spacing or circumferential distance refers to the interval or distance along the outer periphery of pipe 112 in a direction perpendicular to the central axis 122, and such circumferential spacing or circumferential distance does not necessarily mean that pipe 112 is circular in cross-section, because pipe 112 can be a non-circular cross-sectional shape, such as oval, triangular, rectangular, elliptical, etc.

[0037] The groove 120 is elongated and extends parallel to the central axis 122 (see, for example, see...). Figure 1 In cross-section, such as Figure 2 As shown, the groove 120 is concave and thus effectively defines the concave outer surface of the pipe 112. In the illustrated example, the groove 120 has a curved concave shape with a constant radius of curvature. However, in other examples, the groove 120 may have a non-curved concave shape (such as a polygonal shape) or a curved concave shape with a varying radius of curvature.

[0038] The depth (D) of the groove 120 is equal to the distance between the lowest point of the groove 120 and the assumed continuous curve of the outer surface 117 of the pipe 112 above the groove 120, such as... Figure 2As shown by the dashed line. Because the groove 120 effectively reduces the amount of material in the pipe 112, the thickness (T) of the pipe 112 at the groove 120 is less than the thickness of the other non-grooved portions of the pipe 112. Furthermore, because the groove 120 is concave, the thickness (T) of the pipe 112 decreases and then increases along the groove 120 (e.g., along the portion of the pipe 112 defined by the groove 120) as the pipe 112 moves in the circumferential direction toward the initial contact line 136.

[0039] Furthermore, the groove 120 also has a length (L) equal to the distance between the front edge 140 and the rear edge 142 of the groove 120. In some embodiments, the length (L) may be considered as the circumferential length.

[0040] Furthermore, the groove 120 is positioned on the outer surface 117 of the pipe 112 at a circumferential distance (d) from the initial contact line 136. More specifically, the leading edge 140 of the groove 120 is circumferentially (d) from the initial contact line 136, while the trailing edge 142 is circumferentially (d) from the initial contact line 136 plus the length (L) of the groove 120. In some embodiments, the circumferential distance (d) is less than or half the circumference of the corresponding side of the pipe 112. In other words, the groove 120 is positioned on the upper half of the pipe 112.

[0041] In the illustrated example, the conduit 112 of the elastic compression spring 110 has two grooves 120 formed in the outer surface 117 on opposite sides of the initial contact line 136. In one embodiment, the two grooves 120 are circumferentially spaced by the same distance from the initial contact line 136. In other words, the circumferential distance (d) between the two grooves 120 is the same. Furthermore, the grooves 120 can be exactly the same size and shape, such that one side of the conduit 112 is a mirror image of the other side of the conduit 112. In other words, the conduit 112 is symmetrical across the plane of symmetry 124 aligned with the initial contact line 136.

[0042] Although the pipe 112 in the example diagram includes only two recesses 120, in other examples, the pipe 112 may include more than two recesses 120, such as four recesses 120. Figure 2 The conduit 112 is optionally shown having two additional grooves 120 formed in the outer surface 117, wherein each groove 120 is on opposite sides of the initial contact line 136. The two additional grooves 120 may be at the same circumferential distance from the initial contact line 136 and at the same circumferential distance from their respective adjacent grooves 120. In other examples, the conduit 112 may have more than four grooves 120.

[0043] In some examples, the conduit 112 can be made of any material among various elastic (e.g., flexible) materials. In one example, the conduit 112 is made of a thermoplastic elastomer. In another example, the conduit 112 is made of rubber. In one example, the base 114 is made of the same material as the conduit 112; in another example, the base 114 is made of a different material (such as a non-elastic material or a different elastic material). In other examples, the conduit 112 can be made of a metallic material, such as for single-use (e.g., extrusion features) or only for the elastic strain zone of the material (e.g., for small deformations).

[0044] The conduit 112 and the base 114 are formed together to constitute a single, seamless integral structure. However, in other embodiments, the conduit 112 and the base 114 are formed separately and attached together. According to one example, the conduit 112 and / or the base 114 are formed by extruding a thermoplastic elastomer through a die to form a continuous length of the conduit 112 and / or the base 114.

[0045] In one example, the elastic compression spring 110 includes a rounded portion 126 at each intersection between the conduit 112 and the base 114. The rounded portion 126 facilitates deformation (e.g., compression) of the conduit 112 relative to the base 114, particularly the portion of the conduit 112 directly adjacent to the base 114.

[0046] Now will describe Figure 1 and Figure 2 The elastic compression spring 110 functions as a vibration isolator. After the first part 102 contacts the initial contact line 136 of the conduit 112, further movement of the first part 102 relative to the second part 104 in direction 106 compresses (e.g., elastically deforms) the elastic compression spring 110. The compression of the elastic compression spring 110 changes its height (H). The height (H) of the elastic compression spring 110 is defined as the distance between the initial contact line 136 and the mating surface of the base 114 or the bottom of the conduit 112.

[0047] like Figure 10 As shown in Figure 170, the load-displacement curve 174, when Figure 1 and Figure 2 When the elastic compression spring 110 is compressed (e.g., displaced), the anti-compression load generated by the elastic compression spring 110 increases at a fairly constant rate. However, as Figure 3 As shown, once the elastic compression spring 110 is fully compressed (i.e., in Figure 10At displacement A), the first part 102 contacts the front edge 140 of the groove 120. As the thickness (T) of the pipe 112 decreases along the first part of the groove 120, the load-displacement ratio begins to decrease. Under further compression of the elastic compression spring 110, the load-displacement ratio continues to decrease until the displacement of the elastic compression spring 110 reaches a point between displacement A and displacement B (e.g., the midpoint), at which point the load-displacement ratio begins to increase.

[0048] Displacement B corresponds to the displacement of the elastic compression spring 110 where the first part 102 makes contact with the rear edge 142 of the groove 120. The region of the load-displacement curve 174 between displacement A and displacement B is defined as a local load-displacement reduction region 176. At displacement B, the load-displacement curve 174 begins to align with the load-displacement curve 172 of the elastic compression spring 110 without the groove 120. Therefore, the local load-displacement reduction region 176 forms a local deviation from the load-displacement curve 172.

[0049] The characteristics of the localized load-displacement reduction region 176 are based on the configuration of the groove 120. For example, the depth (D) of the groove 120 corresponds to the magnitude of the reduction in the load-displacement rate of the elastic compression spring 110 within the localized load-displacement reduction region 176. The circumferential distance (d) of the groove 120 from the initial contact line 136 corresponds to the displacement of the pipe 112 at which the load-displacement rate of the elastic compression spring 110 begins to decrease. In other words, the circumferential distance (d) of the groove 120 from the initial contact line 136 corresponds to displacement A of the load-displacement curve 174. The length (L) of the groove 120 corresponds to the displacement range of the pipe 112 during which the load-displacement rate decreases and deviates from the load-displacement curve 172. Therefore, the length (L) corresponds to displacement B of the load-displacement curve 174.

[0050] Any characteristic of the groove 120 can be modified to predictably and precisely adjust the load-displacement behavior of the elastic compression spring 110. For example, refer to Figures 5 to 7 If it is desirable for the elastic compression spring 110 to have a local load-displacement reduction region that occurs at a displacement greater than the local load-displacement reduction region 176, then the groove 120 can be positioned at a larger circumferential distance (d) from the initial contact line 136. Figure 5 The circumferential distance (d) of the groove 120 of the elastic compression spring 110 is greater than Figure 1 The circumferential distance of the groove 120 of the elastic compression spring 110. Therefore, when Figure 5 When the elastic compression spring 110 is compressed (for example, see...), Figure 6 and Figure 7 ), Figure 11The localized load-displacement reduction region 186 of the load-displacement curve 184 shown in Figure 180 is due to the elastic compression spring 110. Figure 1 The elastic compression spring 110 begins to move when subjected to a larger displacement (e.g., when compressed). Although not shown, Figure 5 The groove 120 of the elastic compression spring 110 may be wider or narrower (e.g., longer or shorter length (L)) and / or deeper or shallower (e.g., larger or smaller depth (D)) to change the duration and / or amplitude of the local load-displacement reduction region 186 compared to the local load-displacement reduction region 176.

[0051] The direct correlation between the characteristics of the groove 120 and the characteristics of the localized load-displacement reduction region 176 allows the groove 120 to be pre-designed and manufactured to predictably and precisely tune the load-displacement behavior of the elastic compression spring 110, thereby achieving a load-displacement reduction region 176 with desired characteristics, including desired position, amplitude, and duration. Therefore, as combined below... Figure 13 As described in more detail in method 200, the elastic compression spring 110 can be designed and manufactured to achieve unique and predetermined load-displacement behavior in a manner that facilitates reduced design and manufacturing iterations, which helps to improve efficiency, promote cost savings and reduce labor.

[0052] In some applications and contexts, it may be desirable for a resilient compression spring to produce a load-displacement curve with a localized region of increased load-displacement, where the load-displacement ratio increases significantly and sharply to promote increased stiffness across the displacement range of the spring. Therefore, instead of grooves or other features, a resilient compression spring may include ribs that create localized regions of increased load-displacement. For example, refer to... Figure 8 and Figure 9 In order to promote a sharp increase in load-displacement ratio or an increase in bulge within the desired displacement range, the conduit 112 of the elastic compression spring 110 includes at least one rib 150 formed in the outer surface 117 of the conduit 112. As will be described in more detail, the rib 150 causes a local increase in the thickness (T) of the conduit 112, which results in a local increase in the stiffness of the elastic compression spring 110 at the rib 150.

[0053] Ribs 150 are formed in the outer surface 117 of the conduit 112 at circumferentially spaced from the initial contact line 136. In some examples, ribs 150 replace grooves 120, Figure 8 and Figure 9 The elastic compression spring 110 can have the same as Figure 1 and Figure 2 The elastic compression spring 110 has the same features and configuration as described above.

[0054] Rib 150 is elongated and extends parallel to the central axis 122 (see, for example, see...). Figure 8 In cross-section, such as Figure 9 As shown, rib 150 is convex and thus effectively defines the convex outer surface of pipe 112. In the illustrated example, rib 150 has a curved concave shape with a constant radius of curvature. However, in other examples, rib 150 may have a non-curved concave shape (such as a polygonal shape) or a curved concave shape with a varying radius of curvature. The radius of curvature of rib 150 is smaller than the radius of curvature of the outer surface 117 of pipe 112. Therefore, rib 150 protrudes from the outer surface 117 of pipe 112.

[0055] The height (h) of rib 150 is equal to the distance between the top or apex of rib 150 and the assumed continuous curvature of the outer surface 117 of the pipe 112 above the groove 120, such as... Figure 9 As shown by the dashed line. Because the rib 150 effectively increases the amount of material in the conduit 112, the thickness (T) of the conduit 112 at the rib 150 is greater than the thickness of the conduit 112 in other non-rib portions (such as those directly adjacent to the rib 150). Furthermore, because the rib 150 is convex, the thickness (T) of the conduit 112 increases and then decreases along the rib 150 (e.g., along the portion of the conduit 112 defined by the rib 150) as the conduit 112 moves circumferentially toward the initial contact line 136.

[0056] Furthermore, rib 150 also has a length (L) equal to the distance between the front edge 152 and the rear edge 154 of rib 150. In some embodiments, the length (L) may be considered as the circumferential length.

[0057] Furthermore, rib 150 is positioned on the outer surface 117 of pipe 112 at a circumferential distance (d) from the initial contact line 136. More specifically, the front edge 152 of rib 150 is at a circumferential distance (d) from the initial contact line 136, and the rear edge 154 is at a circumferential distance (d) from the initial contact line 136 plus the length (L) of rib 150.

[0058] In the illustrated example, the conduit 112 of the elastic compression spring 110 has two ribs 150 formed in the outer surface 117 on opposite sides of the initial contact line 136. In one embodiment, the two ribs 150 are circumferentially spaced by the same distance from the initial contact line 136. In other words, the circumferential distance (d) between the two ribs 150 is the same. Furthermore, the ribs 150 can be exactly the same size and shape, such that one side of the conduit 112 is a mirror image of the other side of the conduit 112.

[0059] Although the pipe 112 in the example diagram includes only two ribs 150, in other examples, pipe 112 may include more than two ribs 150, such as four ribs 150. Figure 2 The conduit 112 is optionally shown having two additional ribs 150 formed in the outer surface 117, each rib 150 being on opposite sides of the initial contact line 136. The two additional ribs 150 may be spaced equidistant from the initial contact line 136 and equidistant from their respective adjacent ribs 150. In other examples, the conduit 112 may have more than four ribs 150. Additionally, in some examples, although not shown, the conduit 112 may have two or more grooves 120 and two or more ribs 150 to provide an elastic compression spring 110 having both a decreasing and increasing bulge in its load-displacement ratio.

[0060] Now will describe Figure 8 and Figure 9 The elastic compression spring 110 acts as a vibration isolator. In the first part (e.g., similar to...), Figure 2 After the first part 102 (and the part movably in contact with the elastic compression spring 110) contacts the initial contact line 136 of the pipe 112, the first part relative to the second part (e.g., similar to...) Figure 2 The second part 104 (and the part supporting the elastic compression spring 110) further compresses (e.g., elastically deforms) the elastic compression spring 110 upon further movement in direction 106. Figure 12 As shown in Figure 190, the load-displacement curve 194, when Figure 8 and Figure 9 When the elastic compression spring 110 is compressed (e.g., displaced), the anti-compression load generated by the elastic compression spring 110 increases at a fairly constant rate. However, once the elastic compression spring 110 is fully compressed (i.e., at...), the compressive load increases at a relatively constant rate. Figure 12 At displacement A), the first part contacts the front edge 152 of the rib 150. As the thickness (T) of the pipe 112 increases along the first portion of the rib 150, the load-displacement ratio begins to increase (greater than in the case where the elastic compression spring 110 does not have the rib 150). Under further compression of the elastic compression spring 110, the load-displacement ratio continues to increase in this manner until the displacement of the elastic compression spring 110 reaches a point between displacement A and displacement B (e.g., the midpoint), at which point the load-displacement ratio begins to decrease.

[0061] Displacement B corresponds to the displacement of the elastic compression spring 110 where the first part comes into contact with the rear edge 154 of the rib 150. The region of the load-displacement curve 194 between displacement A and displacement B is defined as a localized load-displacement increase region 196. At displacement B, the load-displacement curve 194 begins to align with the load-displacement curve 172 of the elastic compression spring 110 without the rib 150. Therefore, the localized load-displacement increase region 196 produces a localized deviation from the load-displacement curve 172.

[0062] The characteristics of the localized load-displacement amplification region 196 are based on the configuration of the ribs 150. For example, the depth (D) of the ribs 150 corresponds to the increase in the load-displacement rate of the elastic compression spring 110 within the localized load-displacement amplification region 196. The circumferential distance (d) of the ribs 150 from the initial contact line 136 corresponds to the displacement of the pipe 112 at which the load-displacement rate of the elastic compression spring 110 begins to increase. In other words, the circumferential distance (d) of the ribs 150 from the initial contact line 136 corresponds to the displacement A of the load-displacement curve 174. The length (L) of the ribs 150 corresponds to the displacement range of the pipe 112 during which the load-displacement rate increases and deviates from the load-displacement curve 172.

[0063] Any characteristic of rib 150 can be modified to predictably and precisely adjust the load-displacement behavior of the elastic compression spring 110 in a manner similar to that described above with respect to groove 120. The direct correlation between the characteristics of rib 150 and the characteristics of the localized load-displacement amplification region 196 allows rib 150 to be pre-designed and manufactured to predictably and precisely tune the load-displacement behavior of the elastic compression spring 110, thereby achieving a load-displacement amplification region 196 with desired characteristics, including desired position, amplitude, and duration.

[0064] Reference Figure 13 According to one example, a method 200 for tuning a resilient compression spring 110 includes identifying at 202 at at least one difference between the desired load-displacement performance of the resilient compression spring and the actual load-displacement performance. The method 200 further includes at 204 determining a desired local change (e.g., a protrusion) in the load-displacement ratio that begins at a desired first displacement and ends at a desired second displacement and corresponds to at least one difference between the desired load-displacement performance and the actual load-displacement performance. The method 200 also includes updating the resilient compression spring at 204 to achieve the desired load-displacement performance.

[0065] In some embodiments, the local change in the load-displacement ratio is a local decrease in the load-displacement ratio (e.g., a reduction in the protrusion). Furthermore, the updating of the elastic compression spring in step 206 of method 200 includes updating at least one groove 120 formed in the outer surface 117 of the elastic compression spring 100. The groove 120 is configured such that the depth (D) of the groove 120 corresponds to the magnitude of the local decrease in the load-displacement ratio, the circumferential distance (d) of the groove 120 from the initial contact line 136 of the conduit 112 corresponds to a desired first displacement, and the length (L) of the groove 120 corresponds to a desired second displacement.

[0066] In other embodiments, the local change in the load-displacement ratio is a local increase in the load-displacement ratio (e.g., an increase in the size of the bulge). Furthermore, the update of the elastic compression spring in step 206 of method 200 includes updating at least one rib 150 formed in the outer surface 117 of the elastic compression spring 110. The rib 150 is configured such that the height (h) of the rib 150 corresponds to the magnitude of the local increase in the load-displacement ratio, the circumferential distance (d) of the rib 150 from the initial contact line 136 of the conduit 112 corresponds to a desired first displacement, and the length (L) of the rib 150 corresponds to a desired second displacement.

[0067] In the above description, terms such as “upward,” “downward,” “above,” “below,” “horizontal,” “vertical,” “left,” “right,” “above,” and “below” may be used. Where applicable, these terms are used to provide some clarity in dealing with relative relationships. However, these terms are not intended to imply absolute relationships, orientations, and / or directions. For example, with regard to an object, simply by flipping the object, the “upper” surface can become the “lower” surface. However, the object remains the same. Furthermore, unless explicitly stated otherwise, the terms “comprising,” “including,” “having,” and their variations mean “including but not limited to.” Unless explicitly stated otherwise, the enumeration of items does not imply that any or all items are mutually exclusive and / or mutually inclusive. Unless explicitly stated otherwise, the terms “a,” “an,” and “the” also mean “one or more.” Furthermore, the term “multiple” may be limited to “at least two.” Moreover, unless otherwise stated, as defined herein, multiple specific features do not necessarily mean the entire set of specific features or every specific feature of a class of specific features.

[0068] Additionally, in the examples of this specification, "coupled" of one element to another can include direct coupling and indirect coupling. Direct coupling can be defined as one element being coupled to and in contact with another element. Indirect coupling can be defined as coupling between two elements without direct contact between them, but with one or more additional elements between the coupled elements. Furthermore, as used herein, securing one element to another can include direct securing and indirect securing. Also, as used herein, "adjacent" does not necessarily mean contact. For example, an element can be adjacent to another element without contacting it.

[0069] As used in this article, when used with a list of items, the phrase "at least one of..." means that different combinations of one or more of the listed items can be used, and it may be necessary to have only one item from the list. The item can be a specific object, thing, or category. In other words, "at least one of..." means that any combination of items or the number of items from the list can be used, but it may not be necessary to have all the items from the list. For example, "at least one of items A, B, and C" could mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of items A, B, and C" could refer to, for example, but not limited to, two items A, one item B, and ten items C; four items B and seven items C; or some other suitable combination.

[0070] Unless otherwise stated, the terms “first,” “second,” etc., are used herein as labels only and not as imposing any order, orientation, or hierarchical requirements on the items referred to by these terms. Furthermore, reference to an item such as “second” does not require or preclude the existence of an item such as “first” or a lower-numbered item, and / or an item such as “third” or a higher-numbered item.

[0071] As used herein, a system, device, structure, article, element, component, or hardware "configured" to perform a specified function means that it is actually capable of performing the specified function without any changes, rather than merely having the potential to perform the specified function after further modification. In other words, a system, device, structure, article, element, component, or hardware "configured" to perform a specified function is specifically selected, created, implemented, used, programmed, and / or designed for the purpose of performing the specified function. As used herein, "configured" means the existing characteristics of a system, device, structure, article, element, component, or hardware that enable the system, device, structure, article, element, component, or hardware to perform the specified function without further modification. For the purposes of this invention, a system, device, structure, article, element, component, or hardware described as "configured" to perform a particular function may additionally or alternatively be described as "suitable" and / or "operably" to perform that function.

[0072] The illustrative flowcharts included herein are generally presented as logical flowcharts. Therefore, the sequence and labeled steps depicted represent one embodiment of the proposed method. Other steps and methods that are functionally, logically, or effectively equivalent to one or more steps or portions thereof of the illustrated method can be conceived. Furthermore, the format and symbols used are provided to explain the logical steps of the method and are not intended to limit the scope of the method. Although various arrow types and line types may be used in the flowchart, they are understood not to limit the scope of the corresponding method. In practice, some arrows or other connectors may be used only to indicate the logical flow of the method. For example, an arrow may indicate a waiting period or monitoring period of unspecified duration between enumeration steps of the described method. Additionally, the order in which a particular method occurs may (or may not) strictly follow the order of the corresponding steps shown.

[0073] Furthermore, this disclosure includes embodiments as described in the following terms: Clause 1. A resilient compression spring (110) for isolating vibrations between a first part (102) and a second part (104), wherein the first part (102) is movable in a direction (106) relative to the second part (104), the resilient compression spring (110) comprising: A pipe (112) extends along the central axis (122) of the pipe (112), wherein: The central axis of the pipe (112) is perpendicular to the direction (106). The pipe (112) is configured to compress in the direction (106); The conduit (112) includes an outer surface (117) that includes an initial contact line (136) configured to initially receive contact with the first part (102). The conduit (112) further includes at least one groove (120) formed in the outer surface (117), parallel to the central axis (122), and circumferentially spaced from the initial contact line (136); and The at least one groove (120) causes a local reduction in the thickness (T) of the pipe (112) and the stiffness of the elastic compression spring (110) at the at least one groove (120).

[0074] Clause 2. The elastic compression spring (110) according to Clause 1, wherein the conduit (112) further includes two grooves (120) formed in the outer surface (177) of the conduit (112) on opposite sides of the initial contact line (136).

[0075] Clause 3. The elastic compression spring (110) according to Clause 2, wherein the two grooves (120) are circumferentially spaced by the same distance from the initial contact line (136).

[0076] Clause 4. The elastic compression spring (110) as described in Clause 2, wherein: The conduit (112) further includes four grooves (120) formed in the outer surface (117) of the conduit (112); and Two of the four grooves (120) are located on the side of the initial contact line (136) opposite to the other two of the four grooves (120).

[0077] Clause 5. The elastic compression spring (110) as described in Clause 1, wherein: The outer surface (117) of the pipe (112) has a curved convex shape; and The at least one groove (120) has a curved concave shape.

[0078] Clause 6. The elastic compression spring (110) according to Clause 1, wherein the conduit (112) is made of thermoplastic elastomer.

[0079] Clause 7. The elastic compression spring (110) according to Clause 1, wherein the thickness (T) of the conduit (112) decreases and increases along the at least one groove (120) as the conduit (112) moves in the circumferential direction toward the initial contact line (136).

[0080] Clause 8. The elastic compression spring (110) as described in Clause 1, wherein: The depth (D) of the at least one groove (120) corresponds to the reduction in the load-displacement ratio of the elastic compression spring (110); The length (L) of the at least one groove (120) corresponds to the displacement range of the pipe (112), during which the load-displacement ratio decreases; and The circumferential distance (d) of the at least one groove (120) from the initial contact line (136) corresponds to the displacement of the pipe (112), at which the load-displacement ratio of the elastic compression spring (110) begins to decrease.

[0081] Clause 9. A resilient compression spring (110) for isolating vibrations between a first part (102) and a second part (104), wherein the first part (102) is movable in a direction (106) relative to the second part (104), the resilient compression spring (110) comprising: A pipe (112) extends along the central axis (122) of the pipe (112), wherein: The central axis (122) of the pipe (112) is perpendicular to the direction (106). The pipe (112) is configured to compress in the direction (106); The conduit (112) includes an outer surface (117) that includes an initial contact line (136) configured to initially receive contact with the first part (102). The conduit (112) further includes at least one rib (150) formed in the outer surface (117), parallel to the central axis (122), and circumferentially spaced from the initial contact line (136); and The at least one rib (150) causes a local increase in the thickness (T) of the pipe (112) and the stiffness of the elastic compression spring (110) at the at least one rib (150).

[0082] Clause 10. The elastic compression spring (110) according to Clause 9, wherein the conduit (112) further includes two ribs (150) formed in the outer surface (177) of the conduit (112) and on opposite sides of the initial contact line (136).

[0083] Clause 11. The elastic compression spring (110) according to Clause 10, wherein the two ribs (150) are circumferentially spaced by the same distance from the initial contact line (136).

[0084] Clause 12. The elastic compression spring (110) as described in Clause 10, wherein: The conduit (112) further includes four ribs (150) formed in the outer surface (117) of the conduit (112); and Two of the four ribs (150) are located on the side of the initial contact line (136) opposite to the other two of the four ribs (150).

[0085] Clause 13. The elastic compression spring (110) as described in Clause 9, wherein: The outer surface (117) of the pipe (112) has a curved convex shape; and The at least one rib (150) has a curved convex shape, wherein the radius of curvature is smaller than the radius of curvature of the curved convex shape of the outer surface (117) of the pipe (112).

[0086] Clause 14. The elastic compression spring (110) according to Clause 9, wherein the conduit (112) is made of thermoplastic elastomer.

[0087] Clause 15. The elastic compression spring (110) according to Clause 9, wherein the thickness (T) of the conduit (112) decreases and increases along the at least one rib (150) as the conduit (112) moves in the circumferential direction toward the initial contact line (136).

[0088] Clause 16. The elastic compression spring (110) as described in Clause 9, wherein: The height (h) of the at least one rib (150) corresponds to the increase in the load-displacement ratio of the elastic compression spring (110); The length (L) of the at least one rib (150) corresponds to the displacement range of the pipe (112), during which the load-displacement ratio increases; and The circumferential distance (d) of the at least one rib (150) from the initial contact line (136) corresponds to the displacement of the pipe (112), at which the load-displacement ratio of the elastic compression spring (110) begins to increase.

[0089] Clause 17. A method (200) for tuning an elastic compression spring (110), said method (200) comprising: Identify at least one difference between the desired load-displacement performance and the actual load-displacement performance of an elastic compression spring; Determine a desired local decrease in the load-displacement rate that begins at a desired first displacement and ends at a desired second displacement, and corresponds to at least one difference between the desired load-displacement performance and the actual load-displacement performance; and Based on the desired local reduction in the load-displacement ratio, at least one groove formed in the outer surface of the conduit of the elastic compression spring is updated to achieve the desired load-displacement performance.

[0090] Clause 18. The method (200) according to Clause 17, wherein the elastic compression spring (110) is updated such that: The depth (D) of the at least one groove (120) corresponds to the magnitude of the desired local reduction in the load-displacement ratio; The circumferential distance (d) of the at least one groove (120) from the initial contact line (136) of the pipe (112) corresponds to the desired first displacement; and The length (L) of the at least one groove (120) corresponds to the desired second displacement.

[0091] Clause 19. A method (200) for tuning an elastic compression spring (110), said method (200) comprising: Identify at least one difference between the desired load-displacement performance and the actual load-displacement performance of an elastic compression spring; Determine a desired local increase in the load-displacement rate that begins at a desired first displacement and ends at a desired second displacement, and corresponds to at least one difference between the desired load-displacement performance and the actual load-displacement performance; and Based on the desired local increase in the load-displacement ratio, at least one rib formed in the outer surface of the conduit of the elastic compression spring is updated to achieve the desired load-displacement performance.

[0092] Clause 20. The method (200) according to Clause 19, wherein the elastic compression spring (110) is updated such that: The height (h) of the at least one rib (150) corresponds to the magnitude of the desired local increase in the load-displacement ratio; The circumferential distance (d) of the at least one rib (150) from the initial contact line (136) of the pipe (112) corresponds to the desired first displacement; and The length (L) of the at least one rib (150) corresponds to the desired second displacement.

[0093] This subject matter may be implemented in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects as illustrative rather than restrictive. All variations within the meaning and scope of the equivalents of the claims are included within their scope.

Claims

1. A resilient compression spring (110) for isolating vibrations between a first part (102) and a second part (104), wherein the first part (102) is movable in a direction (106) relative to the second part (104), the resilient compression spring (110) comprising: A pipe (112) extends along the central axis (122) of the pipe (112), wherein: The central axis (122) of the pipe (112) is perpendicular to the direction (106). The pipe (112) is configured to compress in the direction (106); The conduit (112) includes an outer surface (117) that includes an initial contact line (136) configured to initially receive contact with the first part (102). The conduit (112) further includes at least one groove (120) formed in the outer surface (117), parallel to the central axis (122), and circumferentially spaced from the initial contact line (136); and The at least one groove (120) causes a local reduction in the thickness (T) of the pipe (112) and the stiffness of the elastic compression spring (110) at the at least one groove (120).

2. The elastic compression spring (110) according to claim 1, wherein the conduit (112) further comprises two grooves (120) formed in the outer surface (177) of the conduit (112) and on opposite sides of the initial contact line (136).

3. The elastic compression spring (110) according to claim 2, wherein the two grooves (120) are circumferentially spaced by the same distance from the initial contact line (136).

4. The elastic compression spring (110) according to claim 2, wherein: The conduit (112) further includes four grooves (120) formed in the outer surface (117) of the conduit (112); and Two of the four grooves (120) are located on the side of the initial contact line (136) opposite to the other two of the four grooves (120).

5. The elastic compression spring (110) according to any one of claims 1-4, wherein: The outer surface (117) of the pipe (112) has a curved convex shape; and The at least one groove (120) has a curved concave shape.

6. The elastic compression spring (110) according to any one of claims 1-4, wherein the conduit (112) is made of a thermoplastic elastomer.

7. The elastic compression spring (110) according to any one of claims 1-4, wherein when the pipe (112) moves in the circumferential direction toward the initial contact line (136), the thickness (T) of the pipe (112) decreases and increases along the at least one groove (120).

8. The elastic compression spring (110) according to any one of claims 1-4, wherein: The depth (D) of the at least one groove (120) corresponds to the reduction in the load-displacement ratio of the elastic compression spring (110); The length (L) of the at least one groove (120) corresponds to the displacement range of the pipe (112), during which the load-displacement ratio decreases; and The circumferential distance (d) of the at least one groove (120) from the initial contact line (136) corresponds to the displacement of the pipe (112), at which the load-displacement ratio of the elastic compression spring (110) begins to decrease.

9. A method (200) for tuning an elastic compression spring (110), the method (200) comprising: Identify at least one difference between the desired load-displacement performance and the actual load-displacement performance of an elastic compression spring; Determine a desired local decrease in the load-displacement rate that begins at a desired first displacement and ends at a desired second displacement and corresponds to at least one difference between the desired load-displacement performance and the actual load-displacement performance; and Based on the desired local reduction in the load-displacement ratio, at least one groove formed in the outer surface of the conduit of the elastic compression spring is updated to achieve the desired load-displacement performance.

10. The method (200) according to claim 9, wherein the elastic compression spring (110) is updated such that: The depth (D) of the at least one groove (120) corresponds to the magnitude of the desired local reduction in the load-displacement ratio; The circumferential distance (d) of the at least one groove (120) from the initial contact line (136) of the pipe (112) corresponds to the desired first displacement; and The length (L) of the at least one groove (120) corresponds to the desired second displacement.

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