FIELD OF ART

[0001] The present application generally relates to canted coil springs, and more particularly, to methods, apparatus, and systems related to a canted coil spring having a variable canted coil spring cross section.

BACKGROUND

[0002] Conventional canted coil springs have tangential points of contact between each coil and one or more flat surfaces of a groove in which the spring is partly or fully received. The noted tangential points of contact are formed by the elliptical coils of the spring contacting the one or more flat surfaces of the groove. Because contact between the coils and the groove occurs at one or more points, a limited contact surface area is available for thermal and/or electrical conductivity.

SUMMARY

[0003] A canted coil spring according to aspects of the disclosure includes a plurality of canted coils generally canted relative to a centerline extending through the coils. At least one coil when viewed in the direction of the centerline comprises a non-elliptical shape and a non- circular shape when the at least one coil is in the unbiased state. The plurality of coils is generally canted at a first coil angle relative to the center line. At least one coil includes at least one section canted at a second coil angle relative to the centerline. The second coil angle is different from the first coil angle when the at least one coil is in an unbiased state.

[0004] A canted coil spring assembly or system according to aspects of the disclosure includes a groove having at least one flat surface and a canted coil spring comprising a plurality of canted coils generally canted relative to a center line extending through the coils. At least one coil when viewed in the direction of the centerline has a non-elliptical shape and a non-circular shape when the at least one coil is in the unbiased state. Furthermore, at least one coil contacts the at least one flat surface with a greater contact area when the at least one coil is in the unbiased state than an unbiased coil of a similar canted coil spring having an elliptical shape or a circular shape. [0005] A method of manufacturing a canted coil spring according to aspects of the disclosure comprises fabricating a wire in a canted helical configuration thereby forming a plurality of coils canted at a first coil angle relative to a centerline extending through the coils, and bending at least one section of at least one coil to a second coil angle relative to the centerline. The first coil angle is different from the second coil angle when the at least one coil is in an unbiased state.

DESCRIPTION OF DRAWINGS

[0006] These and other features and advantages of the present assemblies and methods will become appreciated as the same become better understood with reference to the specification, claims and appended drawings briefly described below.

[0007] FIG. 1 A is a cross-sectional view of an exemplary connector with a canted coil spring. [0008] FIG. IB is a top view of the canted coil spring of FIG. 1 A.

[0009] FIG. 1C is another cross-sectional view of the connector of FIG. 1A with the canted coil spring.

[0010] FIG. ID is a side view of a canted coil spring provided according to aspects of the present apparatus, system, and method.

[0011] FIG. 2 A is a cross-sectional view of a connector having a canted coil spring with an elliptical or circular cross section.

[0012] FIG. 2B is a top view of the connector and the canted coil spring of FIG. 2A showing contact between a coil of the canted coil spring and a flat surface of the connector.

[0013] FIG. 2C is another cross-sectional view of the connector and the canted coil spring of FIGS. 1A-1D.

[0014] FIG. 2D is a top view of the connector and the canted coil spring of FIG. 2C showing contact between a coil of the canted coil spring and a flat surface of the connector. [0015] FIGS. 3A-3D are a top view, a side view, a bottom view and a cross-sectional view of a canted coil spring provided according to aspects of the present apparatus, system and method, where contact between the canted coil spring and flat surfaces of a groove of a connector is shown.

[0016] FIGS. 4A-4D are a top view, a side view, a bottom view and a cross-sectional view of another canted coil spring provided according to aspects of the present apparatus, system and method, where contact between the canted coil spring and flat surfaces of a groove of a connector is shown.

[0017] FIGS. 5A-5D are a top view, a side view, a bottom view and a cross-sectional view of another canted coil spring provided according to aspects of the present apparatus, system and method, where contact between the canted coil spring and flat surfaces of a groove of a connector is shown.

[0018] FIGS. 6 is a side view of another canted coil spring provided according to aspects of the present apparatus, system and method wherein each coil of the spring is shown to have two secondary coil angles.

[0019] FIGS. 7A-7B are a top view and a side view of one example of a canted coil spring according to the embodiment of FIG. 6, where contact between the canted coil spring and flat surfaces of a groove of a connector is shown.

[0020] FIGS. 8A-8B are a top view and a side view of another example of a canted coil spring according to the embodiment of FIG. 6, where contact between the canted coil spring and flat surfaces of a groove of a connector is shown.

[0021] FIGS. 9 A and 9B are a side view and a cross-sectional view of a canted coil spring provided according to another aspect of the present apparatus, system and method with the canted coil spring shown to include alternately configured coils of circular or elliptical cross- sectional shape and coils of non-circular or non-elliptical cross-sectional shape, where the coils have approximately the same coil width. [0022] FIGS. 10A and 1 OB are a side view and a cross-sectional view of a canted coil spring provided according to another aspect of the present apparatus, system and method with the canted coil spring shown to include alternately configured coils of circular or elliptical cross- sectional shape and coils of non-circular or non-elliptical cross-sectional shape, where the coils have different coil widths.

[0023] FIGS. 11A and 1 IB are side views illustrating an exemplary method of fabricating a canted coil spring.

[0024] FIGS. 12A-12C are a side view, a cross-sectional view, and a top view of another exemplary canted coils spring provided according aspects of the present apparatus, system and method and showing the spring contacting flat surfaces of a groove of a connector.

DETAILED DESCRIPTION

[0025] The detailed description set forth below in connection with the appended drawings is intended as a description of embodiments of a canted coil spring having a variable canted coil spring cross section and methods for making the same and is not intended to represent the only forms in which the present assemblies and methods may be constructed or used. The description sets forth the features and the steps for using and constructing the canted coil springs and methods in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the assemblies and methods. As denoted elsewhere herein, like element numbers are intended to indicate like or similar elements or features.

[0026] As used herein, a cross-sectional shape of a coil of a canted coil spring refers to the shape of the coil as it appears when viewed in the direction of a centerline C extending through the canted coil spring.

[0027] Referring to FIG. 1A and 1C, partial cross-sectional views of an exemplary connector 10 are shown. The connector 10 may be used in a number of industries, such as consumer electronics, electrical transmissions, automotive, aerospace, medical, and military, to name a few. The connector 10 may include a shank 12 and a housing 14. The shank 12, which can also be a pin, a shaft or a rod, and the housing 14 include retention grooves 18 and 19, respectively, for receiving at least a portion of the canted coil spring 20. In the exemplary embodiments described herein, the groove 16 is defined by a side wall 17a, side wall 17b, and a top wall 17c located between the side walls 17a and 17b, all of which are collectively referred to as walls 17 of the groove 16. The groove 18 is defined by side wall 17a, side wall 17b, and a bottom wall 17d located between the side walls 17a and 17b, all of which are collectively referred to as walls 17 of the groove 18. In the exemplary embodiments disclose herein, each of the sidewalls 17a, 17b, the top wall 17c, and the bottom wall 17d has a flat surface for contacting the coils 22 of the canted coil spring 20. In the following, the groove 16 or the groove 18 may collectively be referred to as the groove 16 when generally describing contact between a canted coil spring 20 and the grooves 16 and/or 18. The canted coil spring 20 may provide a latching or a locking connection (shown in FIG. 1C) between the shank 12 and the housing 14, function as part of a seal assembly for sealing the connection between the shank 12 and the housing 14, and/or serve as a conduit for heat transfer and/or electrical current transfer between the shank 12 and the housing 14. In alternative embodiments, the housing or the shank but not both has a groove so that the connector provides holding capability.

[0028] Referring to FIG. 2 A, a cross section of the connector 10 and a canted coil spring 30 is shown. The canted coil spring 30 has an elliptical or a circular cross section with an outer diameter or coil width CW that substantially corresponds to the width GW of the groove 16 (the shaft 12 of FIG. 2A is shown without a groove 18). With the groove 16 being rectangular and the canted coil spring 30 being elliptical or circular in cross section, contacts between the coils 32 of the canted coil spring 30 and the flat surfaces of the wails 17 of the groove 16 when the coils 32 are in an unbiased state occur at a tangential contact surface area TC shown in FIG. 2B. The contact surface area TC is shown with dashed lines around a contact point P, which mathematically characterizes the contact between the elliptical or circular coil 32 of the canted coil spring 30 and the flat surfaces of the walls 17 of the groove 16 (i.e., tangential or point contact between an ellipse or a circle and a square or a rectangle). As is readily apparent to a person of ordinary skill in the art, the greater the contact surface area between the coils 32 of the canted coil spring 30 and the groove 16, the greater the bandwidth for flow between the shank 12 and the housing 14 via the coils. For example, in applications where the canted coil spring 30 functions as a heat transfer conduit or an electrical current conduit between the shank 12 and the housing 14, a larger contact surface area than the contact surface area TC of FIG. 2 A would provide greater heat or electrical conductivity between the shank 12 and the housing 14. As described in detail in the following, a canted coil spring according to aspects of the present apparatus, system and method can increase the contact surface area between the canted coil spring and the flat surfaces of the walls 17 of the groove 16 as compared to the canted coil spring 30 of FIG. 2 A. As described, the present apparatus, system and method may be understood to include a connector having increased contact surfaces between a canted coil spring having a plurality of coils and a pair of grooves defining a spring retention groove. The increased contact surfaces lower current or electrical resistance by providing more flow paths between the retention groove and the spring.

[0029] Referring back to FIGS. IB and 1C and also referring to FIGS. 2C and 2D, the canted coil spring 20 according to one exemplary embodiment includes a plurality of coils 22 that are generally canted at an acute coil angle a relative to a centerline C. At least one coil 22 has a non-circular or non-elliptical cross-sectional shape (e.g., appears to have a non-circular or non- elliptical cross-sectional shape when viewed in the direction of the centerline C). In the exemplary embodiment shown in FIGS. 1 A-D and 2C-D, the canted coil spring 20 includes coils 22 that have a substantially square cross-sectional shape (e.g., square with rounded corners) or a substantially rectangular cross-sectional shape (e.g., rectangular with rounded corners) when the coils 22 are in an unbiased state. As used herein, unbiased state is understood to mean lack of external forces tending to cant the coils. Accordingly, when viewed in the direction of the centerline C, which is the view shown in FIGS. 1C and 2C, the coils 22 of the canted coil spring 20 have four sections S that appear to be linear. The sections S may in fact have a curved shape or have a non-linear shape and may only appear linear when the coil 22 is viewed in the direction of the centerline C. The contact surface areas LC between the flat surfaces of the walls 17 of the groove 16 and the corresponding sections S of the coil 22, which is shown in FIG. 2D with dashed lines, is an area defined by a curved line S that mathematically characterizes the contact between the section S and the flat surfaces of the walls 17 of the groove 16. Therefore, one of ordinary skill in the art will readily recognize that the contact surface area LC between the coils 22 and the flat surfaces of the walls 17 of the groove 16 is greater than the contact surface area TC of the coils 32 of the canted coil spring 30 of FIGS. 2A-B. According to aspects of the present apparatus, system and method, the larger contact surface area between each coil is provided by the section S of the coil being bent toward the centerline so as to provide a more flat engagement area with the flat surfaces of the walls 17 of the groove 16. Thus, the coil may be viewed as having a first coil section formed along a first plane and a bent section formed continuously with the first coil section formed along a second plane, which is at an angle with the first plane.

[0030] In the exemplary embodiment shown in FIGS. 1 A-D and 2C-D, the sections S have an acute coil angle Θ relative to the centerline C which is smaller than the acute coil angle a. Coil angle a and coil angle Θ may also be referred to herein as the first coil angle and the second coil angle, respectively. Depending on the functional requirements of a canted coil spring in a particular application, a canted coil spring according to aspects of the present apparatus, system and method can be fabricated to have one or more coils having a second coil angle that is less than or greater than the first coil angle.

[0031] In one exemplary embodiment shown in FIGS. 3A-3D, a canted coil spring 40 has one or more coils 42 which only have one section S that provides a contact surface area LC with one of the flat surface of the wall 17c of the groove 16. As shown in FIG. 3B, the section S has a second coil angle Θ that is less than the first coil angle a. However, as shown in FIG. 3D, the remaining portions of the coils 42 do not have any sections S with a second coil angle, and as a result, have a circular or an elliptical cross-sectional shape. Accordingly, as shown in FIG. 3A, the section S on top of the coils 42 provides a contact surface area LC defined by the line L between the coils 42 and the flat surface of the wall 17c of the groove 16, while as shown in FIG. 3C, the remaining portions of the coils 42 provide contact surface areas TC (not shown) defined by points P between the canted coil spring 40 and the flat surfaces of the other walls 17 of the groove 16.

[0032] In another exemplary embodiment shown in FIGS. 4A-4D, a canted coil spring 50 has one or more coils 52 which have two sections S opposite to each other relative to the centerline C that provide contact surface areas LC with flat surfaces of opposing walls 17 of the groove 16. As shown in FIG. 4B, the sections S have a second coil angle Θ that is less than the first coil angle a. However, as shown in FIG. 4D, the remaining portions of the coils 52, which are the portions on the sides of the coil 52, do not have any sections S with a second coil angle, and as a result, have a circular cross-sectional shape or an elliptical cross-sectional shape. Accordingly, as shown in FIGS. 4A and 4C, the sections S on top and the bottom of the coils 52 provide contact surface areas LC between the coils 52 and the flat surfaces of the walls 17c and 17d of the grooves 16 and 18, respectively, while the remaining portions of the coils 52 provide contact surface areas TC (not shown) between the canted coil spring 50 and the flat surfaces of the walls 17a and 17b of the grooves 16 and 18.

[0033] In another exemplary embodiment shown in FIGS. 5A-5D, a canted coil spring 60 has one or more coils 62 which have two sections S 1 and S2 opposite to each other relative to the centerline C that provide contact surface areas LCI and LC2, respectively, with flat surfaces 17 of two opposing walls of the groove 16. As shown in FIG. 5B, the sections SI have a second coil angle Θ1 that is less than the first coil angle a. The sections S2 have a second coil angle Θ2 that is also less than the first angle a. However, in contrast to the embodiment of FIGS. 4A-4D, the second coil angle Θ1 of the sections SI on top of the coils 62 is different than the second coil angle Θ2 of the sections S2 on the bottom of the coils 62. Accordingly, as shown in FIGS. 5A and 5C, the sections SI on top and the sections S2 on the bottom of the coils 62 provide different contact surface areas LC 1 and LC2, respectively, between the coils 62 and the flat surfaces of the walls 17c and 17d of the grooves 16 and 18, respectively. The remaining portions of the coils 62, which are portions on the sides of the coil 62, do not have any sections S with a second coil angle, and as a result, have a circular cross-sectional shape or an elliptical cross-sectional shape as shown in FIG. 5D. These circular or elliptical portions of the coil 62 provide contact surface areas TC (not shown) between the canted coil spring 62 and the flat surfaces of the side walls 17a and 17b of the groove 16. The spring 60 may be used in applications where initially the contact surface area between one side of the spring and the flat surface of the corresponding side wall 17 should be greater than the other side of the spring. For example, in the unbiased state of the spring 60 shown in FIG. 5B, the contact surface area between sections SI and the flat surface of the top wall 17c is greater than contact surface area between the sections S2 and the flat surface of the bottom wall 17d. However, as the spring 60 is compressed, the contact surface area between the sections S2 and the flat surface of the bottom wall 17d increases, which is a feature that may be preferred in certain applications. For example, because the contact surface area at section S2 increases with compression of the spring, the sections S I may provide a preferred level of electrical conductivity through the spring, while the contact surface area S2 provides an increased preferred level of conductivity through the spring, which can be achieved through increased compression of the spring. In other embodiments, the wall surfaces of the retention groove may be tapered or modified to increase surface contacts with the coils. In other words, the coils, the retention groove, or both may be modified to increase surface contacts.

[0034] In another exemplary embodiment shown in FIG. 6, a canted coil spring 70 may have coils 72a and 72b that include sections SI and S2 on one side or the same side thereof with different second coil angles Θ1 and Θ2, respectively. For example, the coil 72a may have section SI with a second coil angle Θ1, while a second coil 72b may have a section S2 on the same side of the canted coil spring 70 with a second coil angle Θ2 that is different from the second coil angle Θ1. Accordingly, the coils 72a and 72b provide different contact surface areas LC (not shown) with the flat surface of the same wall 17 of the groove 16. The sections S2, which are shown to have a smaller second coil angle Θ, are used to provide high contact surface area with the flat surface of the wall 17 in the unbiased state of the spring 70 and during moderate deflection of the spring 70. The sections SI, however, which are shown to have a larger second coil angle Θ, provide a high contact surface area during excessive deflection. Thus, in the embodiments disclosed herein where the second coil angles Θ on the same side of the canted coil spring vary from one or more coils to one or more other coils, the sections of the coils associated with the varying second coil angles provide high contact surface areas with the flat surfaces of the walls 17 for different deflection ranges of the spring.

[0035] An example of a canted coil spring 70 according to the embodiment of FIG. 6 is shown in FIGS. 7A-7B. The first coil 72a as viewed from left to right in FIG. 7A has a section SI with a second coil angle Θ1 such that the section SI provides a contact surface area LCI with the flat surface of the wall 17c. The second coil 72b has a section S2 with a second coil angle Θ2 which is greater than 01 and slightly less than the first coil angle a. Accordingly, the contact surface area LC2 between the second coil 72b and the flat surface of the wall 17c is smaller than LCI, yet greater than a tangential or point contact TC (not shown) of a typical canted coil spring 30 as shown in FIG. 2 A. The third coil 72c and the fourth coil 72d have sections S3 and S4 with different second coil angles Θ3 and Θ4 which provide different contact surface areas LC3 and LC4, respectively. Therefore, in the exemplary embodiment of FIGS. 7A-7B, the coils 72a-d of the canted coil spring 70 may have different second coil angles Θ1-Θ4 in order to provide different surface contact areas LC1-LC4 with the flat surfaces of the walls 17.

[0036] In another exemplary embodiment shown in FIGS. 8A-8B, a canted coils spring 80 has one or more coils 82a-b with sections S1-S4, where one or more of the sections have negative acute second coil angles relative to the centerline C. The first coil 82a (viewed from left to right in FIG. 8B) has a second coil angle Θ1, which is a negative acute angle relative to the centerline C. In other words, the section SI of the coil 82a extends towards the centerline C rather than extending away from the centerline C. Accordingly, two curved transition areas Tl and T2 (only area Tl is shown in FIG. 8B), which define the transition areas between the section SI and S3 of the coil 82a and 82c and the remaining portions of the coil 82a and 82c, respectively, form two spaced apart contact surface areas BC 1 and BC3 between the coils 82a and 82c, respectively, and the flat surface of the wall 17c. Depending on the sharpness of the curvature of the transition areas Tl and T2, the contact surface areas may provide tangential or point contacts TC or line contact LC between the spring 80 and the flat surfaces of the walls 17. For example, a slow or shallow transition curve Tl provides a line contact area LC while a fast or shape transition Tl may provides a tangential or point contact between the spring 80 and the flat surface of the wall 17c. In this embodiment, the canted coil spring 82 is shown to have two coils 82a and 82c with sections SI and S3, respectively, having negative second coil angles Θ1 and Θ3, respectively, and two coils 82b and 82d with sections S2 and S4, respectively, having positive second coil angles Θ2 and 04.

[0037] In another exemplary embodiment shown in FIGS. 9A-9B, a canted coil spring 90 has coils 92a that have circular or elliptical cross-sectional shapes alternately arranged between coils 92b that have one or more sections S that when viewed in the direction of the centerline C appear to have non-circular or non-elliptical shapes (shown in FIG. 9B). In this exemplary embodiment, both the coils 92a and 92b have the same coil width CW. The coils 92a and 92b are not limited to the alternate arrangement discussed above and can be arranged in any manner in order to achieve a desired function for the spring in a particular application.

[0038] In another exemplary embodiment shown in FIGS. 10A-10B, a canted coil spring 100 has coils 102a that have circular or elliptical cross-sectional shapes alternately arranged between coils 102b that have one or more sections S that when viewed in the direction of the centerline C appear to have non-circular or non-elliptical shapes (shown in FIG. 10B). In this exemplary embodiment, the first coils 102a have a smaller coil width CW1 than the coil width CW2 of the second coils 102b. In this exemplary embodiment, both the coils 92a and 92b have the same coil width CW. The coils 102a and 102b are not limited to the alternate arrangement or the relative sizes discussed above and can be arranged and sized in any manner in order to achieve a desired function for the spring in a particular application.

[0039] Referring now to FIGS. l lA-1 IB, an exemplary method of fabricating a canted coil spring 110 is shown. The canted coil spring 1 10 may be fabricated as a typical canted coil spring having the first coil angle a as shown in FIG. 11A by methods that are known to those of ordinary skill in the art. During or subsequent to such fabrication, one or more sections S of one or more of the coils 1 12 are bent at a bending line BL in the direction of the arrow AR to the same or different second coil angle Θ as shown in FIG. 1 IB. The coils 1 12 can be bent at the same bending line BL, which is shown as an example in FIGS. l lA- l lB, or can be bent at different bending lines (not shown). In FIG. 1 IB, only the top portion of the coil 1 12 is bent at the bending line BL to provide sections S. However, other sides of the coils 112 can be similarly bent in order to provide multiple sides on each coil having sections S for contacting flat surfaces of one or more walls 17 of the groove 16 and 18 at contact surface areas LC as discussed herein. For example, the canted coil spring 20 of FIGS. 1A-1D has coils 22 that are fabricated by bending each coil 22 on four sides to provide a square or rectangular cross section for each coil 22. In a further example, the canted coil spring 50 of FIGS. 4A-4D has coils 52 that are fabricated by bending each coil 52 on two opposing sides to provide two opposing sections S. In yet a further example, the groove 16 may be hex shaped (not shown). Accordingly, the coils of a canted coil spring can be bent on six sides (not shown) in order to substantially correspond to the hex shape of the groove and increase contact surface areas between the canted coil spring and the flat surface of the walls of the groove. Therefore, one of ordinary skill in the art will readily appreciate that the coils of a canted coil spring can be fabricated to have any shape so as to correspond with the shape of a groove and thereby increase the contact surface areas between the coils of the canted coil spring and the flat surface of the walls of the groove.

[0040] In the exemplary embodiments of the canted coil spring and method of fabricating the canted coil spring discussed above, one or more sections of one or more coils of a typical canted coil spring are bent at the same or various second coil angles in order to increase the contact surface area between the coils and the flat surface of the walls of a groove. In these exemplary springs, a coil when viewed in the direction of the centerline C appears to have one or more sections that are linear. As described above, however, these sections are in fact curved and only appear to be linear when viewed in the direction of the centerline C because they are bent at a second coil angle relative to the centerline C. As discussed below, canted coil springs according to other exemplary embodiments are fabricated with one or more coils having one or more actual linear sections in order to increase contact surface area with one or more flat surface of the walls of the groove.

[0041] In one exemplary embodiment, a canted coil spring according to aspects of the present apparatus, system and method includes one or more sections of one or more coils that are linear so as to provide a line contact with the flat surface of one or more walls of the groove 16. Referring to FIG. 12 A, one or more coils 122 of the canted coil spring 120 includes four linear sides SL that may have the same or different length so as to provide a square or rectangular cross-sectional shape. Accordingly, these coils 122 of the canted coil spring 120 are configured at the first coil angle a relative to the centerline C and do not have a section bent at a second coil angle relative to the centerline C. Referring to FIGS. 12B and 12C, the contact areas between the coils 122 and the flat surface of the wall of the groove 16 are actual line contacts. Although the canted coil spring 120 is shown to have four linear sections, one of ordinary skill in the art will readily recognize that one or more coils 122 of the canted coil spring 120 can have portions that are curved and sections that are formed as linear segments.

[0042] A canted coil spring according to aspects of the present apparatus, system and method can provide thermal or electrical conductivity between two parts, such as a connector having male and female parts similar to the shaft 12 and the housing 14 of the connector 10 of FIG. 1A. Thermal and electrical conductivity for the canted coil spring at each coil, around each coil, and based on operative compression range of each coil or various lengths of the spring can be designed based on the particular requirements of each application by providing similar or different levels of contact surface area between the coils and the male and female parts for different compression levels of the spring. The different levels of contact surface area in the unbiased state of the spring or during compression of the spring can be achieved by varying the magnitude of the second coil angle at one or more sections on each coil, varying the magnitude of the second coil angles of one or more coils relative to other coils, and/or varying the coil widths and cross-sectional shapes based on an alternating or other patterns.

[0043] Although limited embodiments of canted coil springs and method of fabricating the canted coil springs have been specifically described and illustrated herein, many modifications and variations will be apparent to those skilled in the art. Accordingly, it is to be understood that the canted coil springs and methods of fabricating these springs according to principles described herein may be embodied other than as specifically described herein. The canted coil springs and methods of fabricating these springs are also defined in the following claims.