Coil spring with ends adapted for coupling without welding

Abstract: Spring apparatus is provided which includes coil springs having intermediate and end coils suitable for interconnection in order to form a continuous spring which maintains a constant load-deflection characteristic over all intermediate coils unaffected by the joint end coils. This configuration therefore finds particular utility in providing bias without compromise of sealing, electromagnetic shielding and/or conductivity.

Description: The invention concerns a spring apparatus comprising a coiled spring having two ends and a plurality of intermediate coils, each coil having a leading portion disposed at a front angle to a normal line to the centerline and a trailing portion disposed at a back angle to the normal line. The present invention generally relates to springs and spring devices for providing bias, sealing, electromagnetic shielding and conductivity, and is more particularly directed to joining of coil springs while at the same time maintaining spring characteristics during deflection, i.e., either radial or axial, compression, of the coils, and extension caused by loading of the spring along a central axis throughout. When spring ends are joined to form a closed spring, such as, for example, an annulus, a further distinguishing feature of such annular springs is their suitability for either radial loading, i.e., along a radius of the annular spring, or axial loading, i.e., along an axis of the spring annulus. The joining of the spring ends is a problem that has been addressed throughout the years but with generally unsatisfactory results. This is primarily due to the fact that the joined ends of the spring do not have the same load deflection characteristics as intermediate portions of the spring, thus resulting in a nonuniform biasing, or loading, of parts which can result in inefficient sealing blockage of electromagnetic waves and nonuniform conductivity. As specifically pointed out in U.S. Patent No. 3,190,633, springs are usually formed of tempered steel and therefore many times cannot be joined at the extreme end by soldering since such joint would be too weak. Nor can they be joined by brazing or welding, since the heat necessary for such joining often destroys the temper of the steel. In an attempt to overcome the problems inherent with welding or soldering, U.S. Patent No. 3,190,633 utilizes a coupling in the form of a tube for the joining of the spring ends. Unfortunately, this introduces a nonlinearity in the spring size; and further, due to the bulkiness of the coupling, uniform load characteristics cannot be obtained throughout the spring structure which results in the limitations as hereinabove discussed. Further elaboration on the disadvantages of joining the ends of a spring by adhesive or a solder includes the time-consuming operation for effecting the union, and the spring is made less efficient, particularly if a number of the spring coils are loaded with solder. This latter configuration also increases in a nonuniform manner the weight of the spring and contributes significantly to a nonlinearity of the spring characteristics in the region of the joined ends. Other known methods of constructing annular devices have been taught in the art over a great number of years. For example, one known method is to provide on one end of the coiled spring, coils of smaller diameter, while another end includes a diameter consistent with intermediate coils of the spring. Coupling is accomplished by forcing the reduced diameter end into the other end, such as set forth in U.S. Patent Nos. 3,011,775 and 3,186,701. However, in all of these springs, the outer coils are supported by inner coils which, in the area of the joint, disrupt the load-deflection characteristics of the outer coils. A further teaching of this type of spring may be found in U.S. Patent No. 3,276,761, in which the end having reduced diameter also has protruding spring forms for engaging spring convolutions of another end of a spring. Again, the overall configuration of the joint to not enable freedom of movement of the outer coils during compression. Alternative teachings of spring joining provide for a spring coil of constant diameter with the ends connected by forcing them on to a connecting member, or plug, which is received and positioned within two ends. In this regard, U.S. Patent No. 735,731 utilizes a screw, or headless plug, with screw threads of substantially the same pitch as the coils of the spring. While this results in an endless helical spring, uniformity of resilience along the helical spring cannot be expected due to the size of the screw utilized for connecting ends of the spring. U.S. Patent No. 1,867,723 discloses a coupling member in the form of a cap. U.S. Patent No. 2,001,835 utilizes a connector formed with a plurality of convolutions of relatively larger diameter for engagement with a constant diameter coil spring. Other teachings of the connector member include U.S. Patent No. 2,778,697, which shows a connector strip provided with a set of semicircular recesses for accepting coils of both ends of a coiled spring. A variation of this design is shown in U.S. Patent No. 3,157,056, in which the strip taught in 2,778,697 is replaced by a cylindrical member having recesses for accepting coil springs. All of this, of course, obviously interfere with the operation of the spring in the area of the coupling member and therefore do not achieve consistent spring characteristics which are necessary for both efficient biasing and sealing. Other connecting members are shown in U.S. Patent No. 2,721,091, showing a rubber embedded helix; U.S. Patent No. 2,779,647, which shows a keeper link arrangement; and U.S. Patent Nos. 3,359,617 which show a spring-connecting member. As set forth in U.S. Patent No. 2,991,064, other known methods for joining helical coils as shown in 4,718,868 include a hook or loop formed on each end of the coil which are connected to form the coil into an annulus and methods which include springs having one or more convolutions at each end which are spaced apart from one another, so they may be connected by being intertwined together to connect the two ends to form an annular spring device. However, all of these methods have serious disadvantages, as pointed out in U.S. Patent No. 2,991,064, and in none of them is produced an annular spring having ends which are so firmly connected that the spring will withstand severe vibration and shock without malformation or separation of the ends or excessive extension or unwinding. Patent Abstracts of Japan, VOL: 12, NO: 227, (M - 713) concerning JP-A-63023037 discloses a device for joining two springs. The ends of the spring cooperate with a separate spring inserted within the coils at the ends of each spring. The insert coils press against the inner surfaces at both ends of the springs to hold the spring together. Due to the pressure exerted by the spring insert on the internal surfaces of the ends of the spring, the properties of the spring in the region of the joint are substantially changed, the spring being substantially stiffer, in particular, in the radial direction than in other sections of the spring at a distance of the joint. US 2,991,064 discloses an annular spring device having the features of the precharacterizing part of claim 1. Further, the springs have not uniform load deflection characteristics due to the interrupted nature of the spring coupling device utilized. The present invention overcomes the difficulties of the prior art and provides an array of coil-joining techniques which are suitable for either axial-type springs, radial-type springs in which the spring utilized can have canted external coils that can be round, elliptical, square or rectangular, or a combination. SUMMARY OF THE INVENTION The spring apparatus, in accordance with the present invention, is characterized by said end coils being disposed inside said intermediate coils at a radial distance therefrom. Importantly, the end coils are disposed at the two ends and include back angle means, defining a trailing portion of at least one end coil locking the end coils together. In this instance, the end coil trailing portion of the end coil has a back angle different from the intermediate coil trailing portion back angle. When joined, the resulting continuous coil may be configured for axial or radial loading. More particularly, the apparatus in accordance with the present invention may include an end coil trailing portion having a decreasing back angle along the length of the end coil. In addition, one of the end coils may be tapered, or both of the end coils may be tapered. In one embodiment of the present invention, the end coils are tapered asymmetric to the centerline of the coil spring. In addition, where the intermediate coils are elliptical, they may be tapered along a major and/or along a minor axis of the coils. In one embodiment of the present invention, the end coils are both tapered asymmetric to the centerline of the coil spring, and in the embodiment where the coil springs are elliptical, the end coils may be elliptical with at least one of the coils being offset along a major axis thereof. The spring ends may be held together by a snap action, that can consist of threading, straight push, or a combination twist and push can cause the ends to be locked together or have interference between coils to cause the coils to engage each other by having the end coils round or elliptical. In this instance, the means for causing the end coils to snap together is an elliptical shape thereof, which causes a portion of the elliptical shaped end coil to extend exterior to a circumference of another end coil. In this last embodiment, the intermediate coils and the end coils may be elliptical. Further, the end coils have a coil height, measured along a minor axis thereof, which is substantially smaller than an intermediate coil height, measured along a minor axis thereof. The hereinabove recited embodiments, as well as the hereinafter recited embodiments of the present invention, enable the coupling of the ends of a spring to form a continuous spring in which the coupling of the end coils do not inhibit or substantially affect the load-deflection characteristics of the continuous spring in the area of the joint end coils. This occurs because the joining configuration, namely, the coupling end portions, do not interfere with the compression or expansion of the intermediate coils of the spring because of their size, position or both with regard to the intermediate coils. In another embodiment of the present invention, the end coils may have a reduced diameter, i.e., "stepped-down" from the size of the intermediate coils. In various embodiments of the present invention, the end coils may have an exterior male, round, elliptical, or offset, and an interior female, round, elliptical, or offset, or alternatively the end stepped-down coils may have both an exterior male configuration and an exterior female configuration. In these embodiments, as hereinafter described in greater detail, the end coils may be threaded, snapped on, pushed on, or pushed on in a manner to provide locking action. Further, a coil in the nature of a hook may be provided for further securing a locking of the end coils together with the hook coil being interior to the intermediate coils. In addition, all of the embodiments of the present invention may be further combined with an elastomer having either a solid center or a hollow center in order to provide sealing, shielding, added force, or enhancing the conductivity by enabling portions of the coil to be bare to enable enhanced conductivity. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention will be better understood by the following description when considered in conjunction with the accompanying drawings in which: Figure 1 is a cutaway side view, generally showing coupling of two end coils to form a continuous coil spring; Figure 2 is a top view of an end coil corresponding to Figure 1, prior to assembly; Figure 3 is a top view of another end coil according to Figure 1, prior to assembly; Figure 4 is a side view of the end coil shown in Figure 2; Figure 5 is a side view of the end coil shown in Figure 3; Figure 6 is a view of the coil spring shown in Figure 1, taken along the line 6-6; Figure 7 is a view of the coil spring shown in Figure 1, taken along the line 7-7; Figure 8 is a view of the coil spring in Figure 1, taken along the line 8-8; Figure 9 is a cutaway side view of an assembled coil spring; Figure 10 is a top view of one end coil of the assembly shown in Figure 9; Figure 11 is a top view of another end coil of the assembly shown in Figure 9, specifically showing portions of elliptical coils thereof for causing the locking action; Figure 12 is a side view of the end coil shown in Figure 10; Figure 13 is a side view of the end coil shown in Figure 11; Figure 14 is a view of the assembly shown in Figure 9, taken along the line 14-14; Figure 15 is a view of the assembly shown in Figure 9, taken along the line 15-15; Figure 16 is a view of the assembly shown in Figure 9, taken along the line 16-16; Figure 17 is a cutaway side view of a spring assembly; Figure 18 is a top view of an end coil of the assembly shown in Figure 17; Figure 19 is a top view of another end coil of the assembly shown in Figure 17, showing protruding elliptical coils which provide for back angle locking; Figure 20 is a side view of the end coil shown in Figure 18; Figure 21 is a side view of the end coil shown in Figure 19; Figure 22 is a view of the assembly shown in Figure 17, taken along the line 22-22; Figure 23 is a view of the assembly shown in Figure 13, taken along the line 23-23; Figure 24 is a view of the assembly shown in Figure 17, taken along the line 24-24; Figure 25 is a cutaway side view of an assembled coil spring; Figure 26 is a top view of an end coil of the assembly shown in Figure 25; Figure 27 is a top view of another end coil shown in Figure 25; Figure 28 is a side view of the end coil shown in Figure 26; Figure 29 is a side view of the end coil shown in Figure 27; Figure 30 is a view of the spring assembly shown in Figure 25, taken along the line 30-30; Figure 31 is a view of the assembly shown in Figure 25, taken along the line 31-31; Figure 32 is a view of the assembly shown in Figure 25, taken along the line 32-32; Figure 33 is a view of the assembly shown in shown in Figure 25, taken along the line 33-33; Figure 34 is a cutaway side view of an assembled coil spring configuration; Figure 35 is a top view of an end coil of the assembly shown in Figure 34; Figure 36 is a top view of another end coil of the assembly shown in Figure 34; Figure 37 is a side view of the end coil shown in Figure 35; Figure 38 is a side view of the end coil shown in Figure 36; Figure 39 is a view of the assembly shown in Figure 34, taken along the line 39-39; Figure 40 is a view of the assembly shown in Figure 34, taken along the line 40-40; Figure 41 is a view of the assembly shown in Figure 34, taken along the line 41-41; Figure 42 is a top view of an assembled spring apparatus; Figure 43 is a cutaway side view of the assembly shown in Figure 42; Figure 44 is a top view of one end coil of the assembly shown in Figure 42; Figure 45 is a top view of another end coil of the assembly shown in Figure 42; Figure 46 is a side view of the end coil shown in Figure 44; Figure 47 is a side view of the end coil shown in Figure 45; Figure 48 is a view of the assembly shown in Figure 43 taken along the line 48-48; Figure 49 is a view of the assembly shown in Figure 43, taken along the line 49-49; Figure 50 is a view of the assembly shown in Figure 43, taken along the line 50-50; Figure 51 is a top view of another spring assembly; Figure 52 is a cutaway side view of the assembly shown in Figure 51; Figure 53 is a top view of one end coil of the assembly shown in Figure 52; Figure 54 is a top view of another coil of the assembly shown in Figure 52; Figure 55 is a side view of the end coil shown in Figure 53; Figure 56 is a side view of the end coil shown in Figure 54; Figure 57 is a view of the assembly shown in Figure 52, taken along the line 57-57; Figure 58 is a view of the assembly shown in Figure 52, taken along the line 58-58; Figure 59 is a view of the assembly shown in Figure 52, taken along the line 59-59; Figure 60 is a cutaway side view of a spring assembly utilizing a circular canted spring with an elliptical snap-on coupling; Figure 61 is a view of the assembly shown in Figure 60, taken along the line 61-61; Figure 62 is a cutaway side view of a spring assembly wherein the intermediate coils are square, and the end coils are elliptical; Figure 63 is a view of the spring assembly shown in Figure 62, taken along the line 63-63; Figure 64 is a cutaway side view of a spring assembly, utilizing rectangular intermediate coils and circular end coils; Figure 65 is a view of the spring assembly shown in Figure 64, taken along the line 65-65; Figure 66 is a cutaway side view of a spring assembly, utilizing circular intermediate coils with circular canted end coils for snap-on engagement; Figure 67 is a view of the spring assembly shown in Figure 66, taken along the line 67-67; Figure 68 is a cutaway side view of a spring assembly, utilizing elliptical canted intermediate coils and elliptical end coils; Figure 69 is a view of the spring assembly shown in Figure 68, taken along the line 69-69; Figure 70 is a cutaway side view of an assembly similar to that shown in Figure 68; Figure 71 is a view of the spring assembly shown in Figure 70, taken along the line 71-71; Figure 72 is a top view of an embodiment of the present invention utilizing male and female end coils; Figure 73 is a side view of an end coil of the spring assembly shown in Figure 72 in which the end coils are abutting; Figure 74 is a side view of another end coil of the spring assembly shown in Figure 72 in which the female end coils is disposed within the intermediate coils; Figure 75 is a view of the end coil shown in Figure 73, taken along the line 75-75; Figure 76 is a view of the end coil shown in Figure 74, taken along the line 76-76; Figure 77 is a top view of a spring assembly similar to that shown in Figure 72 in which the end coils are spaced apart; Figure 78 is a side view of an end coil of the spring assembly shown in Figure 77; Figure 79 is a side view of another end coil of the spring assembly shown in Figure 77; Figure 80 is a top view of another spring assembly similar to that shown in Figure 77 in which one end coil is tapered; Figure 81 is a side view of an end coil of the spring assembly shown in Figure 80; Figure 82 is a side view of another end coil of the spring assembly shown in Figure 80; Figure 83 is a top view of a spring assembly in which the end coils include abutting tapered coils; Figure 84 is a side view of an end coil of the spring assembly shown in Figure 83; Figure 85 is a side view of another end coil of the spring assembly shown in Figure 83; Figure 86 is a spring assembly similar to that shown in Figure 83 with separate tapered end coils; Figure 87 is a side view of an end coil of the spring assembly shown in Figure 86; Figure 88 is a side view of another end coil of the spring assembly shown in Figure 86; Figures 89a and 89b are side views of a spring assembly similar to Figure 77 in which the intermediate coils are rectangular and the one end coil is male, having exterior spaced apart coils; Figures 90a and 90b show a female end coil disposed within intermediate coils for coupling with the end coils shown in Figures 89a and 89b; Figure 91 is a side view of a spring assembly formed by coupling of the end coils shown in Figures 89a and 90b; Figure 92 is a top view of an alternative embodiment of the spring assembly, utilizing two end coils and an insert coil; Figure 93 is a side view of the spring assembly shown in Figure 92; Figure 94 is a partially cutaway side view of the coil assembly shown in Figure 92 when fully assembled; Figure 95 is a view of the spring assembly shown in Figure 93 taken along the line 95-95; Figure 96 is a view of the spring assembly shown in Figure 93 taken along the line 96-96; Figure 97 is a top view of an alternative embodiment of the present invention, similar to Figure 77, in which both the male and female end coils are exterior to the intermediate coils; Figure 98 is a side view of an end coil of the spring assembly shown in Figure 97; Figure 99 is a side view of another end coil of the spring assembly shown in Figure 98 in which the female end coil is exterior to the intermediate coils; Figure 100 is a view of the end coils shown in Figure 98 taken along the line 100-100; Figure 101 is a view of the end coil shown in Figure 99 taken along the line 101-101; Figure 102 is a cutaway side view of the spring assembly shown in Figure 97 at maximum deflection, illustrating independence of the deflection of the intermediate coils from the coupling end coils; Figure 103 is a top view of still another embodiment of the present invention, utilizing triangular end coils; Figure 104 is a side view of one end coil of the spring assembly shown in Figure 103; Figure 105 is a side view of another end coil of the spring assembly shown in Figure 103; Figure 106 is a view of the end coil shown in Figure 104 taken along the line 106-106; Figure 107 is a view of the end coil shown in Figure 105 taken along the line 107-107; Figure 108 is a cutaway side view of the spring assembly shown in Figure 103 at maximum deflection; Figure 109 is a top view of yet another embodiment of the present invention similar to the assembly shown in Figure 103; Figure 110 is a side view of an end coil of the spring assembly shown in Figure 109; Figure 111 is a side view of another end coil of the spring assembly shown in Figure 109; Figure 112 is a view of the end coil shown in Figure 110 taken along the line 112-112; Figure 113 is a cutaway side view of the spring assembly 109 at maximum deflection under a load (not shown); Figure 114 is a view of the end coil shown in Figure 111 taken along the line 114-114; Figure 115 is a view of the end coil shown in Figure 111 taken along the line 115-115; Figure 116 is a top view of a spring assembly, in accordance with the present invention, utilizing an end locking system with a male hook stem; Figure 117 is a side view of a male end coil of the spring assembly shown in Figure 116 showing a male hook stem with a bent latch and abutting coils; Figure 118 is a side view of a female end coil of the spring assembly shown in Figure 116 having round centered coil abutting coils; Figure 119 is a view of the end coil shown in Figure 117 taken along the line 119-119; Figure 120 is a view of the end coil shown in Figure 118 taken along the line 120-120; Figure 121 is a cutaway side view of the spring assembly shown in Figure 116 at maximum deflection and illustrating the coupled end coils not being in interference with the deflection of the intermediate coils upon loading; Figure 122 is a side view of a spring assembly, further including an elastomer surrounding the intermediate and end coils; Figure 123 is a view of the spring assembly shown in Figure 122 taken along the line A-A in one embodiment in which the elastomer has a solid center; Figure 124 is a view of the spring assembly shown in Figure 122 taken along the line A-A in which the elastomer has a hollow center; Figure 125 is a view of the spring assembly shown in Figure 122 taken along the line B-B in which the elastomer has a solid center; Figure 126 is a view of the spring assembly shown in Figure 122 taken along the line B-B in which the elastomer has a hollow center; Figure 127 is a view of the spring assembly shown in Figure 122 taken along the line C-C in which the elastomer has a solid center; Figure 128 is a view of the spring assembly shown in Figure 122 taken along the line C-C in which the elastomer has a hollow center; Figure 129 is a view of the spring assembly shown in Figure 122 taken along the line D-D in which the elastomer has a solid center; Figure 130 is a view of the spring assembly shown in Figure 122 taken along the line D-D in which the elastomer has a hollow center; Figure 131 is a side view of uncanted, circular intermediate and end coils in accordance with the invention; Figure 132 is an end view of the coils shown in Figure 131; Figure 133 is a side view of mating uncanted, circular intermediate and end coils; Figure 134 is an end view of the coil shown in Figure 133; and Figure 135 is a side view of an assembled, uncanted circular coil coil spring. DETAILED DESCRIPTION It should be appreciated that the drawings include specific spring angles and in many cases, dimensions and the specific references are set forth by way of example only and are not be construed as limiting in any way the breadth of the present invention. The specific dimensions are provided for reference and not repeated in the specification for the sake of clarity. Turning now to Figures 1-3, there is shown a spring apparatus 10 which includes a coil spring 12 having a plurality of intermediate coils 14, 16 canted along a centerline 18 of coil spring 12. As more clearly shown in Figures 4 and 5, each coil 12, 14 includes a leading portion 22, 24 disposed at a front angle 26, 28 along a normal line 30 to the centerline 18. As shown in Figures 4 and 5, these intermediate coils have a front angle, for example purposes only, of 30°. Each of the intermediate coils 12, 14 has a trailing portion 34, 36 disposed at a back angle 40, 42 to the normal line 30. As most clearly shown in Figures 2-5, end coils 46, 48 of the spring apparatus are congruent, or continuous, with the plurality of intermediate coils 12, 14 and are disposed at ends 52, 54 of the intermediate coils 12, 14. As shown in Figures 4 and 5, each of the end coils, 46, 48 include trailing portions 58, 60 disposed at back angles 62, 64 which are different from the back angles 40, 42 of the intermediate coils. Alternatively, the back angles 40, 42 may be the same and the front angles 26, 28, different from one another. This difference in back angles enables the end coils 46, 48 to be threaded to one another in a clockwise manner illustrated by the arrow 68 in Figure 1 when the end coil 48 is assembled into the end coil 46 in the direction of the arrow 70, as shown in Figure 1. More particularly, as shown in Figures 4 and 5, the end coil trailing portions 58, 60 have a decreasing back angle along a length of the end coil measured along a centerline 18. As also illustrated in Figures 1-5, one or more of the end coils 46, 48 may be tapered, and as is most easily seen in Figures 4 and 5, the end coils may be tapered asymmetrically to the centerline 18. Thus, the end coils 46, 48 may be threaded, and the tapered ends, along with the difference back angle, provide a friction interference. As more clearly shown in Figures 6, 7 and 8, the intermediate and end coils may be elliptical in which there is a touching or interference between the end coils all around the periphery, as indicated by the shading 72. Figures 6, 7 and 8 show respectively a first coil 78 on the end coil 46, a second coil 80 on the end coil 46, and a third coil 82 on the end coil. Because of the tapered nature of the end coils 46, 48, the height of the intermediate coils 14, 16 enable compression of the spring assembly 10 as indicated by the arrows 86 in Figure 1 without interference from the end coils 46, 48, thus maintaining the load deflection characteristics of the intermediate coils 14, 16 across the union thereof provided by the end coils 46, 48. Turning now to Figure 9, there is shown another embodiment 90, having intermediate coils 92, 94 with end coils 96, 98 as more clearly set forth in Figures 10-13. As most clearly shown in Figures 14-16, end coils 100, 102 are elliptical. As shown in Figure 11, at least one end coil 106 is offset in order to provide a three-area point contact, or locking point for reducing the deflection load of the spring 90 in the area of the coupled end coils 96, 98. As shown in Figure 9, the three areas are locking points, upper locking point 108; a lower back angle, locking point 110; and a lower front angle, locking point 112 (see also Figures 14-16). These locking points are achieved when the end coil 102 is threaded into the end coil 100 in the direction of the arrows 114, 116, as shown in Figure 9. The assembly is further facilitated by the tapered end coils 98. Turning now to Figures 17-24, there is shown yet another embodiment 124 of the present invention similar to that shown in Figures 9-16, which includes intermediate coils 126, 128 and end coils 130, 132 with the end coil 132 tapered, as indicated by the arrow 134 shown in Figure 17. Individual offset coils 138, 140, 142, 144, most clearly seen in Figure 19, provide six locking areas or points which are staggered axially, the points being illustrated at points 148, shown in Figure 21. The contact points are further illustrated in Figures 22-24. As hereinabove described in connection with the embodiment 90, the contact points occur on assembly of the end coil 132 into the end coil 130 by clockwise rotation, indicated by the arrows 150 in Figure 17, as the end coil 132 couples into the end coil 130, as shown by the arrow 152 in Figure 17. The staggered contact area arrangement enables compression of the spring assembly without significant change in its load deflection characteristics in the area of the coupling end coils 130, 132. Turning now to Figure 25, there is shown yet another embodiment 156, with the intermediate coils 158, 160, 162 (see Figures 26 and 27). This embodiment features an end coil 164 having a smaller coil height than the coil height of the intermediate coils 160 to permit greater deflection of the intermediate canted coils 160 along a minor axis, that is, the end coil 164 is "stepped down" from the intermediate coil 160. It should be appreciated that, while the coils are shown as having a right-hand thread, they may also be formed with a left-hand thread. As illustrated in Figures 30-33, contact locking area is along the major axis 164 due to the protruding configuration of individual end coils 166, 168 (see Figure 27). It is to be appreciated that the end coils 162 have a diameter equivalent to the intermediate coils 158, as shown in Figure 26, while only the end coils 164 have a smaller, or step down, diameter, as shown in Figure 29. As hereinbefore discussed, variable back angles, as illustrated on the diagram, create interference and the locking grip between the end coils, as illustrated in Figures 30-33. This unlocking occurs when the end coils 162, 164 are assembled by a clockwise winding, as indicated by the arrow 172, as shown in Figure 25, as the end coil 164 is inserted into the end coil 162 in the direction of the arrow 174, also shown in Figure 25. This assembly is suitable for end coils which are wound in a counterclockwise direction, as indicated by the arrows 176 in Figures 30-33. It should be apparent that due to the reduced diameter of the end coils 164, deflection of the spring assembly embodiment 156, as indicated by the arrows 176 along the minor axis 180 (see Figures 30-33), is possible without significant change in the load deflection characteristics of the spring assembly 156 in the area of the coupled end coils 162, 164. This embodiment is particularly suitable when deflection of the end coils 158, 160 along the minor axis 180 is desired with threading locking. The deflection of the coils at the locking ends result in higher force and greater range of deflection of the intermediate coils 160, without substantial change. Yet another embodiment 186 is shown in Figures 34-41, which includes intermediate coils 188, 190 and end coils 192, 194. As shown in Figure 35 and as most clearly evident in Figure 39, the end coils 192 include at least one individual round coil 196 to provide a deflection stop; and an elliptical locking coil 198 is extended from the intermediate coils 190 with variable back angles 200, 202 (see Figure 38). To create interference, there is a reverse locking grip between the end coils. The deflection stop occurs when the intermediate coils are compressed down to the diameter of the round coils in the direction of arrow 204, as shown in Figure 34. In this embodiment, the end coils 194 are tapered asymmetric to the centerline 206 to the intermediate coils 188, 190 and spring assembly 186. Locking is provided by engagement areas 208, 210, as shown in Figure 40, provided by the coil 198 contact with intermediate coil 186 (see Figure 40). Again, assembly is accomplished by rotating the end coil 194 into the end coil 192 as indicated by the arrow 212 in Figure 34, causing engagement of the end coil 194 into the end coil 192 in the direction of arrow 214. In this embodiment, a locking end 215, end coil 191 provides a stop as indicated by position 214 in Figures 34 and 41 by contact with a first individual end coil 216, four coils wound in a counterclockwise manner, as indicated by the arrow 222 in Figures 39-41. Thus, the spring assembly 186 is assembled by threading the end coils 192, 194 together until positive stop is encountered. Turning now to Figures 42-50, there is shown an alternative embodiment 220 of the spring assembly, or apparatus, wherein intermediate coils 222, 224 and end coils 226, 228 are canted along a centerline 230 with each intermediate coil 224 having a leading portion 234 disposed at a front angle 236 to a normal line 238 and a trailing portion 242 disposed at a back angle 234 to the normal line 238. Preferably, the intermediate coils 222, 224 and end coils 226, 228 are elliptical, and an elliptical shape of at least one individual end coil 248 includes extended portions 250, 252 (see Figure 45) for causing the end coils 226, 228 to snap together with the portions 250, 252 extending exterior to the circumference of end coils 226. Referring specifically to Figures 49 and 50, this provides for engagement between the end coils at alternate selected points 260, 262. Yet another embodiment 266 is shown in Figures 51-59, which includes intermediate coils 266, 268 and end coils 270, 272. This embodiment 266 is similar to embodiment 220, shown in Figures 42-50, except that two individual end coils 276, 278 have a coil height measured along a minor axis 280 (see Figures 57-59) which is substantially smaller than an intermediate coil height measured along the minor axis. This provides for four contact areas 282, 284, 286, 288, as shown in Figures 57-59. Another distinguishing difference between the embodiments 220, 266 is that the location of the leading end coil 292 of the spring apparatus 220 has an end 294, as shown in Figures 45 and 48, which is disposed in a lower left quadrant (see Figure 48) whereas a leading end coil 300 of the spring apparatus 266 has an end 302 disposed in an upper right quadrant, as shown in Figures 54 and 57. Also, as shown in Figures 50 and 59, the end coils 226, 270, respectively, provide positive stops upon assembly, the position of which is indicated at 306 and 308, respectively, in Figures 50 and 59. Alternative embodiments 310, 312, 314, 316, 318 and 320 are shown respectively in Figures 60-71. As shown in Figures 60 and 61, embodiment 310 includes circular intermediate coils 322 with elliptical end coils 324. The embodiment 312 in Figures 62 and 63 includes square intermediate coils 326 and elliptical snap-on end coils 328. The embodiments 314 shown in Figures 62 and 63 and 64 and 65 include rectangular intermediate coils 330 and round snap-on end coils 332. Turning to Figures 66 and 67, the embodiment 316 shown therein includes circular intermediate coils 336 with circular snap-on end coils 338. The embodiment 318 shown in Figures 68 and 69 includes elliptical canted intermediate coils 340 with elliptical end coils 342 which are tapered, as indicated by the arrow 334, and include three locking points indicated at 346. Figures 70 and 71 illustrate the embodiment 320 which utilizes elliptical intermediate coils 350 and elliptical end coils 352 for providing screw-in engagement, with two locking points located at opposite ends of the next-to-the-last leading coils, similar in construction to Figure 69, but not shown. Turning now to Figures 72-76, there is shown an embodiment 356, in accordance with the present invention, having intermediate coils 358, 360 canted along a centerline 362 and having leading portions 364 and trailing portions 366, as hereinbefore describe. End coils 370, 372 are easily distinguished from earlier described embodiments in that the diameter thereof is substantially smaller than the diameter of the intermediate coils 358, 360. Further, as most clearly shown in Figures 73 and 74, the end coils 370 extends outwardly from the intermediate coils 364 along the centerline and the end coil 372 is a female end coil disposed interior to the intermediate coil 360. The embodiment 356 is assembled by threading the end coil 370 into the end coil 372 until the outer portions contact and match one another. It should be evident that, because the end coils 370, 372 are substantially smaller than the intermediate coils 358, 360, deflection of the intermediate coils 358, 360, as indicated by the arrows 374, depression of the coils 358, 360 in the area of the union of the end coils 370, 372 does not affect the load deflection characteristics of the spring assembly 356. Figures 75 and 76 offer end views of the coils 358, 360, 370, 372 and further illustrate the freedom of movement available to the intermediate coils 358, 360. Another embodiment 380, similar to the embodiment 356, is shown in Figures 77-79. The coil assembly 380 includes intermediate coils 382, 384, which may be elliptical, and end coils 386, 388, as more clearly shown in Figures 78 and 79. Figure 77 is a top view of the spring apparatus 380 while Figures 78 and 79 are side views of the spring apparatus 380 prior to assembly. End coils 386 extend outwardly from the intermediate coils 382 in a spaced apart manner, as shown in Figure 78. End coils 388, disposed within the intermediate coils 384, are sized for accepting the end coils 386 in a manner described in connection with the spring apparatus 356. Yet another embodiment 392 is shown in Figures 80-82, Figure 80 being a top view at assembly of the spring apparatus 392. Similar to the spring apparatus 380, intermediate coils 394, 396 may be elliptical, as well as end coils 398, 400. However, in the spring apparatus 392 illustrated in Figures 80-82, the male end coils 398 are both spaced apart and tapered, the taper being illustrated with dashed lines 402. Assembly of the spring apparatus 392 is in accordance with the assembly procedures describing the spring assembly 356. Still another embodiment 406, in accordance with the present invention, is shown in Figures 83-85, with the Figure 83 being a top view of the assembled spring apparatus 406, and Figure 84 being a side view of an end coil 408 prior to assembly. Figure 85 is a side view of end coil 410 prior to assembly. This embodiment 406 is similar to the spring apparatus 356 which includes abutting individual end coils 412, 414 which have a substantially smaller diameter than intermediate coils 416, 418. The end coil 408 is distinguished over the end coil 370 (see Figure 73) in that in addition to abutting, the end coils 412, 414 are tapered as indicated by the dashed line 420. Figure 86 shows the top view of another embodiment 422 of the present invention, which includes intermediate coils 424, 426 congruent with end coils 428, 430. This spring arrangement 422 is similar to the spring arrangement 406 except that the end coils 428 are spaced apart and tapered, as indicated by the dashed line 432. Yet another embodiment 434, in accordance with the present invention, is illustrated in Figures 89a, 89b, 90a, 90b, and 91, Figure 91 being a cutaway side view of the assembled spring apparatus 434. The spring apparatus 434 includes square intermediate coils 436, 438, and is most clearly shown in Figures 89b and 90a around end coils 440, 442. Turning now to Figure 92, there is shown yet another embodiment 446 before assembly, generally showing intermediate coils 448, 450, which may be elliptical, end coils 452, 454, which are abutting and of substantially smaller diameter than the intermediate coils 448, 450, along with an insert coil 456. In this embodiment, both the end coils 452, 454 are female and the insert coil 456 includes male portions 458, 460 sized for insertion into the end coils 452, 454 with center coils 462 providing a stop. A side view of the spring apparatus 446 is shown in Figure 93 prior to assembly, with each of the characterizing angles of the intermediate coils 448, 450, end coils 452, 454, as well as the insert coil 456 being indicated in the figure. Figure 94 shows a cutaway spring assembly 446 at maximum deflection when compressed in the direction of arrows 464 showing the end coils 452, 454 in cross-section. It should be evident from Figure 94 that the reduced diameter of the end coils 452, 454, as well as the insert coils 456, enable the intermediate coils to deflect without bearing against the same and therefore enabling the intermediate coils a constant load deflection characteristic throughout a length thereof. In this embodiment, the end coils 452, 454 may be round, as shown in Figures 95 and 96. Still another embodiment 468 of the present invention is shown in Figures 97-102, with Figure 97 being a top view of the spring assembly 468. The spring assembly 468 is similar to the spring assembly 380 shown in Figures 77-79 with an important distinguishing feature, as hereinafter set forth. The spring apparatus 468 includes intermediate coils 470, 472, with end coils 474, 476, which may be circular, as shown in Figures 100 and 101. Specific angular definition of the intermediate coils 470, 472 and end coils 474, 476 are set forth directly on Figures 98 and 99, which are side views of the end coils 474, 476, respectively. In this embodiment 468, the end coils 474 protrude outwardly from the intermediate coils 470 along a centerline 478. In contrast with the assembly 380, as shown in Figures 77-79, the end coils 476 comprise female coils extending outwardly from the intermediate coils 470 and sized for engagement with male coils 474. The size differential is illustrated in Figures 100 and 101. Because the diameters of the end coils 474, 476 are substantially smaller than the diameters of the intermediate coils 470, 472, the intermediate coils may be deflected (as shown in Figure 102) without interference by the coupling end coils 474, 476. Thus, a constant load deflection characteristic of the intermediate coils is maintained throughout the length of the spring assembly 468. Turning now to Figures 103-108, there is shown another embodiment 482 of the present invention generally including intermediate coils 484, 486 and end coils 488, 490. Figure 103 is a top view of the assembled spring assembly 482, while Figures 104 and 105 are side views of a separated assembly, detailing the front angles 494, back angles 496, as hereinbefore described in connection with earlier presented embodiments of the present invention. Figures 106 and 107 are end views of the end coils 488, 490, respectively, and Figure 107 most clearly shows a triangular configuration of the end coil 490 which is a feature of the assembly 482. A dotted line at 492 indicates interference locations between the end coils 488, 490 to provide locking of the end coils 488, 490 together, resulting in the spring assembly 482. Figure 108 is a cutaway view of the spring assembly 482 at maximum deflection under a force indicated by the arrows 496. It can be seen that in addition to the difference in diameter of the end coils 488, 490 and the intermediate coils 484, 486, the triangular shape of the end coil 490 further enables the compression of the intermediate coils 484, 486, without interference from the end coils 488, 490, thereby not interfering with the load deflection characteristics of the intermediate coils. Figures 109-115 show still another embodiment 510 of the present invention which is similar to the spring assembly 482, shown in Figures 103-108. As shown assembled is a top view of a spring assembly 510 in Figure 109, generally including intermediate coils 512, 514, and, as more clearly shown in Figures 110 and 111, end coils 516, 518. Similar to Figures 104 and 105, Figures 110 and 111 show the specific configuration of the intermediate coils 512, 514 and end coils 516, 518. Figure 112 is an end view of the round end coil 516, which is similar to the end coil 488 of the spring assembly 482 with a greater number of convolutions. Figure 113 illustrates the spring assembly 510 at maximum deflection, showing, as also hereinabove set forth with other embodiments of the present invention, deflection of the intermediate coils 512, 514 without interference from the end coils 516, 518. Figures 114 and 115 illustrate the triangular configuration of the end coil 518, which is similar to the end coil 492 of the spring assembly 482, with a greater number of convolutions. Also shown in Figures 114 and 115 are dotted lines 522, 524 depicting interference locations between the end coils 516, 518 which provide locking of the spring assembly 510, as illustrated in Figures 109 and 115. Figures 116-120 show still another embodiment 530 of the present invention, generally including a plurality of intermediate coils 532, 534 canted along a centerline 536 of the coil spring 530 with each coil 532, 534 having a corresponding leading portion 538, 540, disposed at front angles 542 to normal lines 546, 548 to the centerline 536, and trailing portions 552, disposed at back angles 554, 556 to normal lines 558, 560 to the centerline 536. End coils 564, 566 are congruent respectively with the intermediate coils 532, 536 for providing a joining of the intermediate coils to form the spring assembly, as shown in top view in Figure 116. Importantly, the end coils 564 include at least one hook coil 570, including an end bent latch portion 572 (see Figures 116 and 117) and abutting female coils 574 having a substantially smaller diameter than intermediate coils 532, 534. Locking is provided when the bent latch portion 572 protrudes through the internal female coils 574, as shown in Figures 116 and 121. End views of the end coil 570 are shown in Figure 119, while the end views of the generally circular end coils 574 are shown in Figure 120. A stop is provided upon latching of the two end coils 564, 566 by abutment of the intermediate coils 532, 534, as shown in Figure 116. Figure 121 illustrates the advantage of the present invention by depicting the spring assembly 530 in cross-section at full deflection in response to loading in the direction of arrows 580. As illustrated, full deflection of the intermediate coils 532, 534 may be achieved without interference from the end coils 564, 566, thereby enabling a constant load deflection characteristic of the intermediate coils 532, 534 over the continuous length of the assembly 530. It should be appreciated that all of the hereinabove recited embodiments may be filled with an elastomer or plastic, having either a solid or a hollow coil. This configuration is illustrated in Figures 122-130 which shown an elastomer 184 surrounding a spring assembly 586, having intermediate coils 588, 590 and end coils 592, 594. The purpose of the elastomer is to provide uniform loading, as well as sealing, in addition to providing enhancement of conductivity and electromagnetic shielding, depending upon the consistency of the elastomer exposure of one or more coils or portions of coils to enhance conductivity and/or electromagnetic shielding. Figures 123 and 124 show cross-sections taken along the line 123-123 of Figure 122 for a solid core elastomer 584 (see Figure 123) and the elastomer 584 having a hollow center 598, as shown in Figure 124. Similarly, Figures 125 and 126 correspond to view 125-125 taken from Figure 122. Figures 127 and 128 show solid and hollow core elastomer 584 taken along the line 127-127 in Figure 122. Figures 129 and 130 show solid and hollow core elastomers viewed along the line 129-129 of Figure 122. Also shown in Figures 126 and 128 are contacted area points 602-605, illustrating mechanical linkage between the end coils 592, 594, as hereinbefore described in greater detail. While the present invention has been hereinabove described in terms of canted coils, it should be appreciated that the coils need not be canted. In that regard, Figures 131-135 illustrate an embodiment 610, in accordance with the present invention, in which intermediate coils 612, 614 are circular and not canted; and end coils 618, 620 are also circular and uncanted. Figures 131 and 132 show side and end views, respectively, of the intermediate coils 612 and end coils 618 whereas Figures 133 and 134 show side and end views, respectively, of the intermediate coils 614 and end coils 620. Figure 135 illustrates the assembly of the end coils 618, 620. It should also be appreciated that in the embodiments hereinabove described that the end coils may be of the same or different configuration. That is, the elliptical end coil 324 may be used with a round end coil 332. Although there has been hereinabove described a coil spring with ends adapted for coupling without welding, in accordance with the present invention, for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. It should be further appreciated that the coupling of spring ends in accordance with the present invention is particularly suitable for springs providing bias while at the same time enabling efficient sealing, electromagnetic shielding and/or conductivity.

Claims: Spring apparatus comprising a coiled spring (12) having two ends and a plurality of intermediate coils (14, 16), each coil (12, 14) having a leading portion (22, 24) disposed at a front angle (26, 28) to a normal line (30) to the centerline (18) and a trailing portion (34, 36) disposed at a back angle (40, 42) to the normal line (30), with end coils (46, 48) disposed at the two ends and having a trailing portion (58,60) of at least one end coil (46, 48) locking the end coils together, the end coil trailing portion (58) of said at least one end coil (46) having a back angle (62) different from the intermediate coil trailing portion back angle (40), characterized in that said end coils (46, 48) are disposed inside said intermediate coils (12, 14) at a radial distance therefrom. The spring apparatus according to claim 1, wherein said intermediate coils are canted along the centerline (18) of the coiled spring (12). The spring apparatus according to claim 2, wherein said end coil trailing portion (58, 60) has a decreasing back angle along a length of the end coil. The spring apparatus according to claim 3, wherein at least one of the end coils (46, 48) is tapered. The spring apparatus according to claim 3, wherein both of the end coils (46, 48) are tapered. The spring apparatus according to claim 5, wherein the end coils (46, 48) are tapered asymmetrically to the centerline (18) of the coiled spring (12). The spring apparatus according to claim 6, wherein the elliptical end coils (46, 48), upon locking, engage one another along an entire periphery thereof (72). The spring apparatus according to claim 2, wherein the intermediate coils (14, 16) are elliptical, the end coils (46, 48) are elliptical and are tapered. The spring apparatus according to claim 8, wherein the end coils (46, 48) are both tapered asymmetrically to the centerline of the coiled spring (12). The spring apparatus according to claim 4, wherein the coiled spring coils (14, 16) are elliptical, the end coils (46, 48) are elliptical, and at least one (46) of the end coils (46, 48) is radially offset (Fig.2). The spring apparatus according to claim 10, wherein the elliptical end coils (46, 48), upon locking, engage at selected points along a periphery of the end coils (46, 48) for locking. The spring apparatus according to claim 2, wherein another of the end coils has a trailing portion disposed at a back angle (64) equal to the back angle (42) of the intermediate coils, the intermediate coils (14, 16) and the end coils (46, 48) are elliptical, the one end coil (98) is tapered and has at least one coil (106) radially offset. The spring apparatus according to claim 2, wherein the intermediate coils (188, 190) are elliptical, another of the end coils (192) has a trailing portion disposed at a back angle equal to the back angle of the intermediate coils (188, 190) and the one end coil (194) is tapered with at least one tapered round coil (196). The spring apparatus according to claim 1 , wherein one of said coils is a male end coil (386) extending along a centerline and passing axially through a joining region of the intermediate coils (382, 384) and another of said end coils is a female end coil (388) disposed interior to said intermediate coils (384). The spring apparatus according to claim 14, wherein said male end coil (408) comprises abutting coils (412, 414). The spring apparatus according to claim 15 , wherein the abutting coils (412, 414) are tapered. The spring apparatus according to claim 14, wherein said female end coil (410) comprises abutting coils. The spring apparatus according to claim 14, wherein said intermediate coils (382, 384) are elliptical. The spring apparatus according to claim 14, wherein said intermediate coils are elliptical (358, 360) and the male (370) and female (372) end coils are round. The spring apparatus according to claim 14, wherein said intermediate coils (486) are rectangular. The spring apparatus according to claim 14, wherein said intermediate coils (436, 438) are rectangular and the male (440) and female (442) end coils are round. The spring apparatus according to claim 14, wherein said male end coil (398) comprises spaced apart coils. The spring apparatus according to claim 22 , wherein the spaced apart coils (398) are tapered. The spring apparatus according to claim 22, wherein said female end coil (400) comprises spaced apart coils. The spring apparatus according to claim 22, wherein said intermediate coils (394) are elliptical. The spring apparatus according to claim 14, wherein said intermediate coils (358, 360) are elliptical and the male (370) and female (372) end coils are round. The spring apparatus according to claim 22, wherein said intermediate coils are rectangular. The spring apparatus according to claim, 22, wherein said intermediate coils (330) are rectangular and the male (332) and female end coils are round. The spring apparatus according to claim 22, wherein said intermediate coils (358, 360) are elliptical and the male end coils are triangular. The spring apparatus according to claim 29, wherein the female end coils are round. The spring apparatus according to claim 22, wherein the intermediate coils (394, 396) are elliptical and the male and female end coils are elliptical (398, 400). The spring apparatus according to claim 22, wherein the intermediate coils are elliptical (394, 396) and the male (370) and female (372) end coils are round. The spring apparatus according to claim 32, wherein the intermediate coils (394, 396) are canted. The spring apparatus according to claim 22, wherein one of the male and female end coils is round (370, 372) and another of the male and female end coils is elliptical (398, 400). The spring apparatus according to claim 34, wherein the intermediate coils (470) are round. The spring apparatus according to claim 34, wherein the intermediate coils are elliptical (472). The spring apparatus according to claim 2, wherein one of said end coils is a male coil and coil (474) extending along the centerline (478) and passing axially through a joining region of the intermediate coils and another of said end coils being a female end coil (476) extendins along the centerline and passing axially through said joining region of the intermediate coils.

Inventors: BALSELLS PETER J, BALSELLS, PETER J.
Applicants: BAL SEAL ENG CO INC, BAL SEAL ENGINEERING COMPANY, INC.
Application year: 1995
Main classification: F16F1
IPC codes: F16F1, F16F3