Anti-loss device for screws and mounting unit

Description

[0001] The invention relates to a captive device for a screw with an annular sleeve for insertion into a through-hole in a workpiece. The invention also relates to an assembly unit comprising a screw, a bushing, and a captive device.

[0002] A two-part loss prevention device for a screw is known from European Patent Application EP 2 000 681 A2. The loss prevention device has an annular sleeve that is slidably arranged on the shaft of the screw. At its end facing the screw head, the sleeve has an inner diameter that is slightly larger than a smooth shaft section of the shaft, but smaller than the outer diameter of the threaded section of the shaft. At its end opposite the head, the annular sleeve has a radial projection with which it is arranged in another annular outer sleeve. The annular sleeve is thus captively received in the outer sleeve in a direction away from the workpiece. The outer sleeve is intended to be inserted into a through-hole in a workpiece.The annular sleeve, which rests against the screw shaft, has spring tongues at its upper end, facing the screw head, that are bent inward toward the shaft. These spring tongues extend from the annular sleeve and thus protrude toward a central longitudinal axis of the sleeve. The annular sleeve and the annular outer sleeve are each tubular and therefore have a continuous peripheral wall.

[0003] A two-part captive device for a screw is known from US patent 4,621,961. The captive device consists of a first ring sleeve that directly surrounds the shaft of the screw and whose inner diameter is slightly larger than a smooth shaft section, but smaller than the outer diameter of the threaded section of the screw. The first ring sleeve has leaf-shaped spring tongues that extend from the head end of the ring sleeve toward the threaded section. The first ring sleeve has a truncated cone-shaped section whose outer diameter decreases starting from the head end. A second ring sleeve is inserted into a through hole in a workpiece. The second ring sleeve has a truncated cone-shaped inner bore whose inner diameter decreases away from the screw head end.The first ring sleeve is pressed together with the screw into the second ring sleeve until outwardly projecting locking projections on the ends of the leaf-shaped spring tongues snap outwards and behind the underside of the second ring sleeve.

[0004] European Patent Application 2 136 088 A2 discloses a one-piece loss prevention device in which a ring sleeve can be pushed onto the shaft of the screw. The ring sleeve can then be inserted into a through-hole in a workpiece. The ring sleeve has leaf-shaped spring tongues that extend inward towards the shaft of the screw. The leaf-shaped spring tongues enable the ring sleeve to sit springily in the through-hole of the workpiece, and the inwardly projecting ends of the leaf-shaped spring tongues also prevent the screw from slipping out of the ring sleeve. The ring sleeve is tubular and has punched-out sections that help to form the spring tongues.

[0005] US Patent Application Publication US 2014 / 0357137 A1 discloses an annular spring sleeve intended for establishing an electrically conductive connection between a socket and a pin inserted into the socket. The annular sleeve is bent from a strip of material, and in the finished state of the annular sleeve, there is a gap between the beginning and end of the strip of material. The sleeve forms a cage-like structure between three ring sections with several struts distributed around the circumference and extending longitudinally.

[0006] German patent DE 955101 discloses a lock nut with a hexagonal outer contour and resilient locking teeth projecting inward toward a central longitudinal axis. The locking teeth are designed to engage the thread of a threaded bolt.

[0007] The invention is intended to improve a captive device for a screw; an assembly unit with a screw and a captive device and a method for assembling a screw and a captive device with regard to a simple structure and tolerance insensitivity.

[0008] According to the invention, a captive device for screws with the features of claim 1 is provided. A captive device with an annular sleeve for insertion into a through-bore in a workpiece is provided, in which the annular sleeve is provided with at least one leaf-shaped spring tongue which extends from the annular sleeve and projects in the direction of a central longitudinal axis of the sleeve.

[0009] Surprisingly, a structurally very simple design of a loss prevention device comprising an annular sleeve with at least one leaf-shaped spring tongue not only allows for a simple, cost-effective construction, but also for high tolerance insensitivity. This is because the leaf-shaped spring tongue prevents a screw from moving axially out of a through-hole, while at the same time allowing radial displacement of the screw within the through-hole. The screw is thus held captive in the through-hole, and at the same time, the screw can be displaced radially within the through-hole in order to align it with threaded holes in another workpiece. The loss prevention device according to the invention is particularly advantageous for fastening hoods or covers.On the one hand, screws can be pre-assembled in through-holes and the hood or cover with the pre-assembled screws can then be automatically moved to another workpiece, for example a cylinder head, without having to worry about the screws falling out of the through-holes. The loss-prevention device according to the invention then allows the screws to be moved radially relative to the through-holes during assembly in order to compensate for tolerances. This is particularly advantageous when the hood or cover is to be fastened with numerous screws. With reasonable effort, it is then practically impossible to rule out the possibility of tolerances occurring between the position of the through-holes on the hood and the threaded holes in the workpiece, for example in the cylinder head. Such tolerances can be easily compensated for using the loss-prevention device according to the invention.The through-hole can, for example, be provided in a sleeve, which is then pressed or injected into a hood, a cover, or another workpiece. The captive device then forms an assembly unit together with the bushing and the screw. In a further development of the invention, the annular sleeve has a slot extending from a first edge to a second edge.

[0010] The sleeve can thus be designed to be spring-loaded and inserted into a through-hole under preload. For example, the sleeve has a larger diameter than the through-hole in its relaxed state. For assembly, the sleeve is compressed and, after being inserted into the through-hole, released again. The sleeve then springs back and holds its position in the through-hole through friction. Designing the annular sleeve with a continuous slot, i.e., as a slotted sleeve, also allows for the compensation of through-hole tolerances.

[0011] In a further development of the invention, the annular sleeve has a section which forms a closed ring.

[0012] If the retaining device is to be used in sheet metal components with only a small thickness, a sufficiently high holding force can be achieved in a through-hole of the sheet metal component by means of a section of the sleeve designed as a closed ring. The retaining device can then be pressed into the through-hole, for example. The outer diameter of the retaining device can then be selected slightly larger than the inner diameter of the through-hole to achieve a press fit. The inner diameter of the through-hole and the outer diameter of the retaining device can also differ in shape to achieve a sufficient clamping effect of the retaining device in the through-hole.

[0013] In a further development of the invention, three leaf-shaped spring tongues, in particular 3 to 8 spring tongues, are evenly distributed over the circumference of the annular sleeve.

[0014] Using three leaf-shaped spring tabs, a screw can be held securely and evenly loaded. Above all, it is possible to hold the screw centered to the through-hole using three spring tabs, i.e., with the screw shank at a uniform distance from the wall of the through-hole. The spring tabs can hold the screw either by having the threaded section of the screw with a larger outer diameter than an unthreaded section of the screw shank, or by engaging the screw thread, thereby securing the screw in the through-hole. For flatter components, particularly sheet metal components, more than three spring tabs can be advantageous.

[0015] According to the invention, the at least one leaf-shaped spring tongue extends from the annular sleeve initially parallel to the central longitudinal axis of the sleeve, then obliquely to the central longitudinal axis towards the central longitudinal axis and at least until shortly before the free end of the leaf-shaped spring tongue again parallel to the central longitudinal axis.

[0016] In this way, a screw can be easily inserted into the loss protection device, for example if the loss protection device is already mounted in a through-hole. The screw is inserted into the annular sleeve with its threaded section first and then pushes the leaf-shaped spring tongues apart by running onto the section of the spring tongues that runs diagonally to the central longitudinal axis. The areas at the end of the leaf-shaped spring tongue, which again extend parallel to the central longitudinal axis, then ensure that the spring tongues apply even pressure to the screw shaft. These areas of the leaf-shaped spring tongues, which run parallel to the central longitudinal axis, extend from the diagonal section at least to just before the free end of the leaf-shaped spring tongue.

[0017] Immediately before their free end, the leaf-shaped spring tongues can extend away from the central longitudinal axis at an angle. This can, for example, create a V-shaped end of the leaf-shaped spring tongues, which can then engage the screw threads.

[0018] In a further development of the invention, the annular sleeve and the at least one spring tongue are formed from a stainless steel sheet.

[0019] In this way, the loss prevention device can be designed to be both spring-elastic and corrosion-resistant.

[0020] In a further development of the invention, the at least one spring tongue extends from a first edge of the sleeve and the sleeve is provided in the region of a second edge, which is opposite the first edge, with at least one projection projecting radially outwards, away from the central longitudinal axis.

[0021] By means of one or more such projections, the sleeve can be securely anchored in a through-hole. The projections are advantageously implemented in the form of sheet metal sections bent radially outward at an angle. These sheet metal sections then rest resiliently against the inner wall of the through-hole, thereby securing the sleeve in the through-hole.

[0022] In a further development of the invention, the annular sleeve is bent from a band-shaped strip of material.

[0023] For example, the sleeve can be made from a punched and pre-bent sheet metal strip. Depending on the diameter of the required sleeve, a piece of the appropriate length is cut from the sheet metal strip. The sheet metal strip is then bent in such a way that the spring tongues are already given their intended shape and, if necessary, any projections on the sleeve are bent out, which then ensure that the sleeve is securely held in the through-hole. The sheet metal strip section is then bent into the round sleeve and inserted into a through-hole in its bent state.

[0024] In a further development of the invention, there is a gap between the beginning and the end of the sheet metal strip in the finished state of the annular sleeve.

[0025] This creates a slotted sleeve that, on the one hand, can exert a spring action, allowing it to be reliably mounted and secured in a through-hole. On the other hand, such a slotted sleeve can compensate for tolerances in the diameter of the through-hole.

[0026] In a further development of the invention, the sleeve has a section which forms a closed ring, wherein, viewed in the direction of a central longitudinal axis of the ring, the at least one spring tongue extends from the section forming the closed ring and wherein a longitudinal extension of the spring tongue is one to three times the length of the section forming the closed ring.

[0027] With such comparatively short spring tongues, the spring effect is less pronounced, but this can be compensated for by using more than three spring tongues, for example. This allows for high reliability even with such flat loss prevention devices, which are intended, for example, for insertion into sheet metal components.

[0028] In a further development of the invention, two spring tongues arranged next to one another in the circumferential direction are separated from one another by means of an incision in the sleeve.

[0029] This allows the spring tongues to be formed very easily. The notch can be created mechanically, for example, by sawing or punching, or by primary forming, for example, when the sleeve with the spring tongues is manufactured as a plastic injection-molded part.

[0030] The problem underlying the invention is also solved by an assembly unit with a screw, a bushing and a loss prevention device according to the invention, wherein the loss prevention device is inserted into the bushing and the screw extends at least partially into the bushing and is held in the bushing by the loss prevention device.

[0031] Such an assembly unit with a bushing, retaining device, and screw can be supplied and, for example, automatically inserted into through holes in a hood or cover that match the bushing. Of course, it is also possible to inject the assembly unit during the production of the hood, cover, or other workpiece. After the bushing is attached to the hood, cover, or other workpiece, the screw is then held captive to the hood, cover, or other workpiece.

[0032] The problem underlying the invention is also solved by an assembly unit with a screw, a sheet metal component and a loss prevention device according to the invention, wherein the loss prevention device and the screw are inserted into a through-opening of the sheet metal component.

[0033] The loss prevention device according to the invention can be used very advantageously, particularly with comparatively thin sheet metal parts, for example with a thickness between 3 mm and 5 mm, or with thin plastic components.

[0034] Further features and advantages of the invention will become apparent from the claims and the following description of a preferred embodiment of the invention in conjunction with the drawings. Individual features illustrated in the drawings and / or described in the description may be combined with one another without exceeding the scope of the invention, as long as these combinations fall within the wording of the appended claims. The drawings show: Fig. 1 a side view of a non-inventive loss prevention device, Fig. 2 an exploded view of a non-inventive assembly unit with the loss prevention device of the Fig. 1 , Fig. 3 a diagram to explain the manufacture of the assembly unit of the Fig. 2 , Fig. 4 a section-wise sectional view of a first workpiece with two assembly units not according to the invention and a second workpiece with two threaded holes, Fig. 5 a view of a loss prevention device not according to the invention according to a further embodiment obliquely from below, Fig. 6 a plan view of the loss prevention device of the Fig. 5 , Fig. 7a view of the section plane AA in Fig. 6 , Fig. 8 a schematic representation of the steps in inserting the loss prevention device of the Fig. 5 and a screw in through-holes of a sheet metal component, Fig. 9 a view of a non-inventive loss prevention device according to a further embodiment obliquely from above, Fig. 10 a plan view of the loss prevention device of the Fig. 9 , Fig. 11a view of the section plane AA in Fig. 10 , Fig. 12 a representation of detail B from Fig. 11 , Fig. 13 a view of a non-inventive loss prevention device according to a further embodiment obliquely from below Fig. 14 the loss prevention device of the Fig. 13 in a plan view, Fig. 15 a view of the section plane AA in Fig. 14 and Fig. 16 the enlarged detail B from Fig. 15 , Fig. 17 a loss prevention device according to an embodiment of the invention from above, Fig. 18 the loss prevention device of the Fig. 17 in a side view, Fig. 19 the loss protection of the Fig. 17 in a top view, Fig. 20 the loss protection of the Fig. 17 in the installed state as an assembly unit with a screw in a first position, Fig. 21 the loss protection of the Fig. 17 when installed as an assembly unit with a screw in a second position and Fig. 22 the loss protection of the Fig. 17 when installed as an assembly unit with a screw in a third position.

[0035] The representation of the Fig. 1 shows a loss prevention device 10. The loss prevention device 10 has an annular sleeve 12, which is provided with a total of three leaf-shaped spring tongues 14, wherein in the side view of the Fig. 1 only two of the spring tongues 14 can be seen. The annular sleeve 12 has a first edge 16 and a second edge 18, which is opposite the first edge 16. The two edges 16, 18 run parallel to each other. The leaf-shaped spring tongues 14 extend from the first edge 16. A central longitudinal axis 20 of the annular sleeve 12 is in Fig. 1 indicated by a dotted line.

[0036] The leaf-shaped spring tongues extend, as best seen from the Fig. 1 As can be seen from the spring tongue 14 shown on the left, starting from the first edge 16, it initially runs parallel to the central longitudinal axis 20 and then at an angle to the central longitudinal axis 20 towards the central longitudinal axis 20. Following the inclined section, there is again a section of the spring tongue 14 running parallel to the central longitudinal axis, which then extends to the free end of the leaf-shaped spring tongue 14.

[0037] In the area of ​​the second edge 18, three radially outwardly projecting projections 22 are provided, wherein in the illustration of the Fig. 1 Only two of these projections are visible. The projections 22 are formed by sheet metal tabs bent radially outward at an angle.

[0038] The anti-loss device 10 is designed to be inserted into a through-hole. When installed, the projections 22 rest against an inner wall of the through-hole and ensure that the anti-loss device 10 is securely held in the through-hole.

[0039] The leaf-shaped spring tongues 14 are intended to rest with their end section at the free end on the shaft of a screw and thereby secure the screw.

[0040] Fig. 2 shows an exploded view of an assembly unit 30 according to the invention with the loss prevention device 10 from Fig. 1 The assembly unit 30 has a screw 32, a loss protection device 10 and a bushing 34. The loss protection device 10 is designed to be inserted into a cylindrical through-bore 36 in the bushing 34. The screw 32 is then pushed with a threaded portion 38 first into the through-bore 36 and thus into the loss protection device 10. In the assembled state, the spring tongues 14 of the loss protection device 10, which then rest against the shaft of the screw 32, prevent the screw 32 from falling out of the bushing 34. The free ends of the spring tongues 14 can rest against a threadless portion 40 of the screw shaft of the screw 32, which extends between the thread 38 and a screw head 42. In a direction towards the bushing 34, the screw 32 cannot fall out of the bushing due to the screw head 42.In the opposite direction, the free ends of the spring tongues 14 abut the beginning of the threaded section 38, thereby preventing the screw from falling out of the through-bore 36 of the bushing 34. However, the free ends of the spring tongues 14 can also rest on the thread 38. This also holds the screw 32 in the through-bore 36 of the bushing 34 by means of the spring tongues 14.

[0041] In Fig. 2 It can be seen that the sleeve 12 is designed as a slotted sleeve and has a slot 44 which extends from the first edge 16 of the sleeve 12 to the second edge 18 of the sleeve 12. The slot 44 ensures that the annular sleeve 12 can spring up and down to a certain extent. This allows tolerances of the inner diameter of the through-bore 36 to be compensated for, and the sleeve 12 can also be pressed together for insertion into the through-bore 36. After springing up, the sleeve 12 then rests with its outer circumference and also with the projections 22 under spring preload against the inner wall of the through-bore 36. The loss protection device 10 can thus be secured in the through-bore 36 of the bushing 34.

[0042] The representation of the Fig. 3 shows the production of the assembly unit 30 of the Fig. 2 in various work steps. First, the loss prevention device 10 is formed from a pre-punched and pre-bent sheet metal strip. This is done by cutting off a section 46 from a longer sheet metal strip. This section has three spring tongues 14 and a strip 48, which is then later formed into the annular sleeve 12 of the loss prevention device 10. The spring tongues 14 extend from a first edge 16 of the strip 48, and the second edge 18 of the strip 48 is provided with a total of six incisions 50, with two incisions 50 each defining a projection 22 between them in the finished state of the loss prevention device 10.The section 46 is then pre-bent so that the spring tongues 14 already receive their later shape, specifically a first section running parallel to the strip 48, then a section running obliquely to the strip 48 and then again a section running parallel to the strip 48 up to the free end of the spring tongues 14. The areas between the incisions 50 are bent obliquely to the strip 48 so that the projections 22 then extend radially obliquely outwards in the finished state of the loss prevention device 10.

[0043] The strip 48 is then bent into a circle to form the anti-loss device 10. There is then a small gap between the two ends 52, 54 of the strip 48 of the section 46, which, see Fig. 2 , then forms the slot 44 in the sleeve 12 of the anti-loss device 10.

[0044] The captive device 10 is then inserted into the through-bore 36 of the bushing 34, with the bushing 34 shown in section. As already explained, the annular sleeve 12 is slightly compressed for this purpose, thus reducing its outer diameter. After insertion into the through-bore 36, the annular sleeve 12 then springs open, so that the captive device 10 is securely held in the through-bore 36.

[0045] Subsequently, the screw 32 is inserted with the threaded portion 38 first into the through-bore 36 of the bushing 34. When the screw 32 is inserted, the front end of the screw presses the spring tongues 14 radially outward, so that the free ends of the spring tongues 14 slide over the threaded portion 38 and then, after the end of the threaded portion 38, spring back inward and then rest against the unthreaded portion 40 of the shaft of the screw 32.

[0046] The completed assembly unit 30 is in Fig. 3 on the far left. It can be seen that the spring tongues 14 of the anti-loss device 10 now prevent the screw 32 from falling out of the bushing 34 by the free ends of the spring tongues 14 striking the head-side beginning of the threaded section 38 of the screw 32. The screw 32 can therefore, in Fig. 3 upwards, do not slip out of the through hole 36 of the threaded bushing 34. In the opposite direction, in Fig. 3 i.e. downwards, the head 42 of the screw prevents it from falling through the bushing 34.

[0047] The assembly unit 30 thus has the screw 32, the loss protection 10 and the bushing 34, wherein the screw 32 is held captively in the bushing 34 by means of the loss protection 10.

[0048] You can already see the completed assembly unit 30, which is on the far left in Fig. 3 shown partially in section, it can be seen that the shaft of the screw and thus also the threaded section 38 of the screw 32 can be moved radially within the through hole 36. This allows tolerances in the position of a counter thread in a workpiece to be compensated.

[0049] Fig. 4 shows a representation of a first workpiece 60 into which two assembly units 30 not according to the invention are inserted. For this purpose, the first workpiece 60 has two stepped through-bores into which the respective bushings 34 are inserted such that an end of the bushings 34 facing the screw head of the screw 32 of the assembly units 30 is arranged flush with a surface of the first workpiece 60. An opposite end of the bushings 34 is also arranged flush with the associated surface of the workpiece 60.

[0050] A second workpiece 62 is provided with two threaded holes 64, 66. The first workpiece 60 is designed, for example, as a cover or hood, and the second workpiece 62 is designed, for example, as a cylinder head. It is shown in the Fig. 4 It can be seen that the Fig. 4 left mounting unit is now aligned relative to the left threaded bore 64 of the second workpiece 62 such that a central longitudinal axis 20 of the loss prevention device 10, a central longitudinal axis of the screw 32, a central longitudinal axis of the bushing 34 and a central longitudinal axis of the first threaded bore 64 in the second workpiece 62 coincide.

[0051] However, a lateral distance between the first threaded hole 64 and the second threaded hole 66 in the second workpiece 62 does not exactly correspond to the distance between the central longitudinal axes of the left bushing 34 and the right bushing 34 in the first workpiece 60.

[0052] Specifically, a distance between the central longitudinal axes of the two bushings 34 in the first workpiece 60 is smaller than a distance between the central longitudinal axes of the two threaded holes 64, 66 in the second workpiece 62.

[0053] Since the screw 32 is held in the right-hand bushing 34 by means of the spring tongues 14 of the anti-loss device 10, the screw 32 can be seen in the illustration of the Fig. 4 to the right within the through hole 36 of the bushing 34 until the central longitudinal axis of the screw 32 is aligned with the central longitudinal axis of the second threaded hole 66 of the second workpiece 62. This lateral displacement of the screw shaft of the screw 32 within the through hole 36 of the right bushing 34 is in Fig. 4 This can be easily recognized by the fact that the threaded section 38 of the screw 32 is at a distance A2 from the right-hand boundary of the through-hole 36 of the bushing 34 and at a distance A1 from the left-hand boundary of the through-hole 36 of the bushing 34, where A1 is greater than A2. Since the central longitudinal axes of the right-hand screw 32 and the second threaded hole 66 are now aligned, the screw 32 can be easily screwed into the second threaded hole 66 with its threaded section 38. At the same time, the Fig. 4 left screw 32 can be screwed into the first threaded hole 64 without any problems, since the central longitudinal axes of the left screw 32 and the first threaded hole 64 are also aligned.

[0054] The non-inventive anti-loss device 10 and the non-inventive assembly units 30 thus make it possible to arrange the screws 32 in the first workpiece 60 in a captive manner and at the same time to compensate for tolerances between the threaded bores 64, 66 in the second workpiece 62 and the central longitudinal axes of the two bushings 34 in the first workpiece 60.

[0055] The loss prevention devices 10 not according to the invention are also inexpensive to produce, easy to assemble and also ensure reliable securing of the screws 32 in the bushings 34.

[0056] Fig. 5 shows a non-inventive anti-loss device 70, which has a first section 72 in the form of a closed ring, from which a plurality of spring tongues 74 extend. The spring tongues 74 are each separated from one another by V-shaped incisions and are arranged at equal distances from one another in the circumferential direction of the anti-loss device 70. The section 72 forming a closed ring is cylindrical. The spring tongues 74 are then each bent obliquely inward, toward the central longitudinal axis of the section 72. The spring tongues 74 are each approximately flat and are therefore formed by simply bending a section of material.

[0057] The spring tongues 74 each have a prism-like shape with two slanting side edges and a circumferentially extending upper edge. A total of eight spring tongues 74 are arranged equally spaced adjacent to one another in the circumferential direction.

[0058] The loss prevention device 70 is intended for insertion into sheet metal components with only a small thickness, cf. Fig. 8 . High clamping forces can be achieved by section 72, which forms a closed ring. For example, section 72 is pressed into a through-hole in a sheet metal component whose inner diameter is slightly smaller than the outer diameter of section 72. Alternatively, section 72 can also have a non-circular shape in order to achieve a sufficiently strong clamping effect in a round through-hole in a sheet metal component.

[0059] Fig. 6 shows the loss protection 70 of the Fig. 5 in a top view. The circular design of section 72 in the form of a cylindrical tube and the spring tongues 74 bent inward toward a central longitudinal axis 76 of section 72 can be seen.

[0060] Fig. 7 shows a view of the section plane AA of the loss prevention device 70 of the Fig. 6 .

[0061] In the view of the Fig. 7 It can be clearly seen that, viewed in the longitudinal direction of the central longitudinal axis 76, the spring tongues 74 are approximately twice as long as the section 72. In this way, a sufficient spring effect of the spring tongues 74 and a sufficient clamping effect of the section 72 can still be achieved while at the same time keeping the overall height of the loss prevention device 70 low.

[0062] Fig. 8 shows various steps for forming an assembly unit from the loss prevention device 70, a screw 80 and a sheet metal component 90 with several through openings.

[0063] The anti-loss device 70 is first pushed onto the screw 80 until it rests against the underside of the head of the screw 80. In this section adjacent to the underside of the head, the shaft of the screw 80 is not provided with a thread, so that the outer diameter of the shaft in this area is smaller than in the area that is provided with a thread. The spring tongues 74 rest with their free ends on the outside of the shaft. The spring tongues 74 thus prevent the anti-loss device 70 from Fig. 8 downwards, over the threaded section of screw 80.

[0064] The screw 80 with the loss-prevention device 70 is then inserted into a through-hole 100 with the threaded section first. The through-hole has a diameter that is larger than the outer diameter of the threaded section of the screw 80. As soon as the section 72 of the loss-prevention device 70 reaches the upper limit of the through-hole 100, the movement of the screw 80 is initially stopped. The screw 80 can then be moved further by applying a pressing force with which the section 72 is pressed into the through-hole 100. It has already been explained that the outer diameter of the section 72 of the loss-prevention device 70 is slightly larger than the inner diameter of the through-hole 100. When the loss-prevention device 70 is pressed into the through-hole 100, a press fit is created.

[0065] In Fig. 8 In the two illustrations at the left end of the sheet metal component 90, the captive fasteners 70 are shown fully pressed into the sheet metal component 90. The ends of the spring tongues 74 are approximately level with the underside of the sheet metal component 90, and the peripheral edge of the section 72 opposite the spring tongues 74 is flush with the top side of the sheet metal component 90. The captive fastener 70 prevents the screw 80 from falling out of the through-hole 100 of the sheet metal component 90. However, the screw 80 can still be easily turned in the through-hole 100, for example, to fasten the sheet metal component 90 to another component with a threaded bushing.

[0066] The Fig. 8 The screw 80 shown on the far left is slightly shifted to the left relative to a position concentric with the through-hole 100. Such a radial displacement relative to the through-hole 100 is possible due to the non-inventive anti-loss device 70, since the spring tongues 74 can yield in the radial direction. The anti-loss device 70 thus enables tolerance compensation. The illustration of the Fig. 9 shows another non-inventive anti-loss device 110. The anti-loss device 110 has a section 112 that forms a closed ring. Starting from the section 112, a total of eight spring tongues 114 are provided, which are evenly spaced from one another in the circumferential direction of the anti-loss device 110. The spring tongues 114 are each separated from one another by rectangular incisions 116 and bent inward toward a central longitudinal axis of the section 112. The spring tongues 114 can be formed, for example, by simply sawing into a pipe section.

[0067] The incisions 116 extend beyond the bent part of the spring tongues 114, see also Fig. 12 .

[0068] Fig. 10 shows a view of the loss prevention device 110 from above, Fig. 11 a view of the section plane AA in Fig. 10 und Fig. 12 the enlarged detail B from Fig. 11 .

[0069] Fig. 13 shows a further loss prevention device 120. The loss prevention device 120 has a section 122 which forms a closed ring. Fig. 13 A total of eight spring tongues 124 are provided on the lower edge of the section 122, which are bent inwards in the direction of a central longitudinal axis of the section 122.

[0070] However, the spring tongues 124 on the anti-loss device 120 are bent by more than 90°, so that they, see Fig. 13 , extend upwards again. A screw would fit into the retaining device 120 of the Fig. 13 i.e. introduced from bottom to top.

[0071] In order to facilitate the insertion or pressing of the loss prevention device 120 into a through-hole of a sheet metal component, an edge of the section 122, which is opposite the spring tongues 124, is bent inwards, see also Fig. 16 . The edge 126 of the section 122 thus serves as an insertion aid when inserting or pressing in the loss prevention device 124.

[0072] Fig. 14 shows a top view of the loss prevention device 120, Fig. 15 a view of the section plane AA of the Fig. 14 und Fig. 16 the enlarged detail B from Fig. 15 .

[0073] The loss prevention devices according to the invention can be manufactured either from sheet metal strips, material strips in general, alternatively from tubes, discs, or even as injection-molded parts. The sheet metal strips, tubes, or discs can be made, for example, from spring steel, aluminum, or carbon steel. Other materials such as metals, non-ferrous metals, plastics, and hybrid materials can be used in the manufacture of the loss prevention device according to the invention. Plastics, in particular, can be coated to achieve greater grip and adhesive strength, especially between the loss prevention device and a workpiece bore or bushing into which the loss prevention device is inserted. Depending on the environmental requirements, in particular mechanical requirements and corrosive ambient temperature, an optimal adaptation of the loss prevention device can be achieved.

[0074] Fig. 17 shows a loss prevention device 210 according to the invention in a view obliquely from above. The loss prevention device 210 is designed as an annular bushing and has a section 212 which is designed as a closed ring. From this section 212, the diameter of the bushing decreases to a Fig. 17 The end 230 with a smaller diameter of the bushing shown top right. This reduced diameter is achieved by a total of six spring tongues 214, which extend from the section 212 and are separated from each other by notches 216. The notches 216 extend from the Fig. 17 The spring tongues 214 extend from the end 230 of the captive device 210 shown at the top right, extend to the annular section 212, and have a circular end. Starting from the section 212, the spring tongues 214 initially run parallel to a central longitudinal axis 218 of the captive device 210, see also Fig. 18 , then run obliquely towards the central longitudinal axis 218 and then run parallel to the central longitudinal axis 218 again until their free end.

[0075] From section 212 towards the Fig. 17 The first end 228 with a larger diameter of the loss prevention device 210 shown at the bottom left has a structure in the form of a ring cage 220. This ring cage 220 has a convex, bulging shape and consists of a total of six struts 222, which are separated from one another by slot-shaped recesses 224. The recesses 224 begin immediately adjacent to the section 212 and end in front of the Fig. 17 The struts 222 also start at section 212 and run to the end 228 of the retaining device 210 located at the bottom left. Fig. 17 The free end 228 of the retaining device 210 shown at the bottom left. After the end of the recesses 224, two adjacent struts 222 are connected to each other. Starting from the Fig. 17 From the end 228 of the loss prevention device 210 shown at the bottom left, a total of six notches 226 extend a short distance in the direction of the section 212. The notches 226 extend a short distance between the recesses 224 and each notch 226 is arranged centrally between two recesses 224. Following the Fig. 17 At the end 228 of the recesses 224 shown at the bottom left, the struts run parallel to the central longitudinal axis 218. Adjacent to this, the struts 222 extend convexly bulged or curved outwards up to section 212. Due to the bulged shape of the struts 222, the recesses 224, and the incisions 226, the loss prevention device 210 can be compressed in the area of ​​the annular cage 220, for example, in order to be inserted into a bore with a smaller diameter. The annular cage 220 is designed to be resiliently compressed inwardly and thereby apply a radially outward-acting preload in order to be clamped firmly in a bore.

[0076] The diameter of the anti-loss device 210 is at the Fig. 17 The first end 228 shown in the lower left is larger than the section 212. At the Fig. 17 At the second end 230 shown at the top right, the diameter of the loss prevention device 210 is then smaller than in section 212. Fig. 17 The end 230 of the captive device shown top right is designed to rest on the shaft of a screw to be secured, see also the Fig. 20 bis 22 .

[0077] Fig. 18 shows a side view of the loss prevention device 210. It can be clearly seen that the diameter of the loss prevention device 210, starting from a first end 228, initially increases slightly in the area of ​​the ring cage 220. This is caused by the convex outwardly bulging shape of the struts 222. Approximately halfway along the length of the ring cage 220, the diameter of the loss prevention device 210 decreases again, and then in section 212, it assumes a smaller value than the first end 228. As described, from section 212 in the direction of the Fig. 18 upper end 230 the spring tongues 214. In Fig. 18 It is clearly visible that the spring tongues 214, starting from section 212, which has the shape of a closed ring, initially curve outward in a convex manner toward the central longitudinal axis 218, then curve concavely again in a direction parallel to the central longitudinal axis 218, and then run parallel to the central longitudinal axis 218 again until the second end 230. The diameter at the second end 230 is smaller than in section 212.

[0078] As stated, the diameter of the loss prevention device 210 is larger at the first end 228 than at the annular section 212 and the annular section 212 has a larger diameter than the second end 230. A bore into which the loss prevention device 210 is inserted should have a diameter that is larger than the outer diameter of the section 212 and slightly smaller than the diameter at the first end 228 or approximately the same as the diameter at the first end 228. When inserted into such a bore, the annular cage 220 is thereby compressed so that the loss prevention device 210 is fixed relative to the bore.A screw that is to be secured against falling out of the bore by the loss prevention device 210 should expediently have a shaft section with a diameter that is smaller than or equal to the inner diameter at the second end 230, and another shaft section, usually a threaded section, whose outer diameter is larger than the inner diameter at the second end 230. As a result, the loss prevention device 210 can then secure such a screw against falling out of the bore and the screw can still be moved relative to the loss prevention device 210 in and against its central longitudinal axis.

[0079] Fig. 19 shows the loss protection 210 of the Fig. 17 in a view from above. The view is directed Fig. 19 on the Fig. 18 upper end 230. The spring tongues 214, which are separated from each other by the notches 216, are clearly visible. Fig. 19 the ring cage 220 with the struts 222 and the recesses 224 between the struts 222. The lower end 228 of the anti-loss device 210, see Fig. 17 und Fig. 18 , is in Fig. 19 hidden.

[0080] Fig. 20 shows the loss protection 210 of the Fig. 17 bis 19 in the installed state. The captive element 210 has been inserted into a bushing 234, which has a cylindrical bore with a diameter D1 and at its Fig. 20 left and right ends has a radially projecting collar. The bushing 234 can, for example, be inserted into a workpiece by being injected into the workpiece during manufacture. For example, hoods, covers, or the like can be provided with the bushing 234. It has already been explained that the loss prevention device 210 can generally be inserted into bores in which screws are to be secured. Such bores can also be drilled into solid workpieces or provided in bushings, which are then fixed in or on the workpiece in a suitable manner.

[0081] In the presentation of the Fig. 20 A machine screw 232 is shown, which is inserted sectionally into the bore of the bushing 234. The screw 232 has a head 236, a smooth, unthreaded shank portion 238, and a threaded portion 240. Between the end of the threaded portion 240 and the free end opposite the head 236, there is also an unthreaded portion 242 with a reduced outer diameter compared to the thread 240 and a truncated cone-shaped tip. This portion 242 serves to insert the screw 232 into a threaded bore as easily as possible, even if the screw 232 is slightly offset from the threaded bore in the radial direction.

[0082] The head 236 has an outer diameter which is larger than the inner diameter D1 of the bore in the bushing 234. In a direction from left to right in Fig. 20 The screw 232 can therefore not fall out of the bushing 234. The outer diameter of the smooth shaft section 238, which adjoins the head 236, is smaller than the outer diameter of the threaded section 240. Since the inner diameter D1 of the bore in the bushing 234 is larger, in the illustrated embodiment about twice as large as the outer diameter of the threaded section 240, the screw 232 could Fig. 20 fall out of the bushing 234 to the left if the anti-loss device 210 were not provided. The spring tongues 216 of the anti-loss device 210 rest with their areas, which extend from the second end 230 of the anti-loss device 210 and run parallel to the central longitudinal axis of the anti-loss device 210, on the outer circumference of the smooth shaft section 238 of the screw 232. Even if the spring tongues 216 rest on the shaft section 238 with a certain spring pressure, the screw 236 can Fig. 20 can still be moved to the left and right relative to the bushing 234. Falling out of the screw 236 in a direction to the left in Fig. 20 This is prevented by the fact that when the screw 236 is turned from the position of the Fig. 20 is displaced to the left relative to the bushing 234, the left end of the threaded portion 240 abuts the second end 230 of the captive device 210 and the screw 236 is thereby prevented from moving further to the left out of the bushing 234.

[0083] The captive device 210 itself is not pulled out of the bore of the bushing 234, since the captive device 210 is held frictionally in the bore of the bushing 234 in the area of ​​the annular cage 220. This is achieved by the struts 222 applying an outward preload force. The struts 222 can additionally be provided with a coating on their outer side, which provides greater grip or greater adhesion between the struts 222 and the bore of the bushing 234.

[0084] Based on the state of the Fig. 20 The screw 236 can be moved in the radial direction relative to the bore of the bushing 234. This allows tolerances between a position of the bushing 234 and a position of a threaded bore into which the thread 240 of the screw 236 is to be screwed to be compensated. Fig. 20 It can be seen that the screw 236 is in the radial direction, in Fig. 20 i.e. upwards or downwards, until the outer diameter of the thread 240 rests against the inner wall of the bore of the bushing 234. Such a radial displacement is made possible by the loss prevention device 210, such as Fig. 22 can be seen. For this purpose, the captive device 210 has several, in particular six, spring tongues 214, which are evenly distributed over the circumference of the captive device. Within the scope of the invention, at least the spring tongues should be evenly distributed over the circumference to enable radial mobility of the shaft of a screw.

[0085] Fig. 20 shows the captive device 210 arranged in the bushing 234, which has an inner diameter D1. This inner diameter D1 is larger than a diameter D2 of a bore of a bushing 244, which is in Fig. 21 is shown.

[0086] Fig. 21 shows the screw 236 and the captive device 210, which are inserted into the bore of the bushing 244 with the inner diameter D2. As already explained, the inner diameter D2 is smaller than the inner diameter D1 of the bore of the bushing 234 of the Fig. 20 .

[0087] The loss prevention device 210 rests with its spring tongues 216 again on the outer circumference of the thread-free, smooth shaft section 238 of the screw 236 and thereby prevents the screw 236 from Fig. 21 from right to left out of the bushing 244. Due to the smaller inner diameter D2 of the bore of the bushing 244, the struts 222 are more compressed in the area of ​​the ring cage 220 of the loss prevention device 210 than in the state of Fig. 20 However, the struts 222, through their radially outwardly acting spring preload, ensure that the captive device 210 is securely fixed in the bore of the bushing 244 by friction. The screw 236 can be tightened starting from the Fig. 21 shown state in the radial direction to the bore of the bushing 244, in Fig. 21 i.e. up and down. The amount of this possible offset, in Fig. 21 up or down, is in Fig. 21 each indicated by the letter A.

[0088] Fig. 22 shows the screw 236 in the socket 244 of the Fig. 21 , whereby the screw 236 is compared to the state of the Fig. 21 was shifted in the radial direction by the length A, in Fig. 22 downwards. The thread 240 now rests on one side against the inner wall of the bore of the bushing 244. This is Fig. 22 shown below. To the opposite, in Fig. 22 The thread 240 now has a distance of 2A from the wall section of the bore of the bushing 244 shown above. Even in this state of the Fig. 22 The screw 236 can still be screwed into a threaded hole. The captive device 210 ensures that the screw 236 cannot slip out of the bushing 244 and also enables the compensation of tolerances between a position of the bushing 244 and the position of a threaded hole (not shown) into which the screw 236 is to be inserted. Furthermore, the captive device 210 can also compensate for tolerances in the inner diameter D1, D2 of a hole or sleeve 234, 244.

[0089] For example, the bushings 234, 244 can be injected into a plastic cover during its manufacture. When the plastic cover is then placed, for example, on a machine housing or even on a cylinder head, the captive fasteners 210 can compensate for tolerances between the position of the threaded holes and the position of the bushings 234, 244 in the plastic cover. The captive fastener 210 can also compensate for tolerances in the inner diameter of the holes in the bushings 234, 244.

[0090] In the maximum radially deflected state of the screw 236 relative to the bushing 244, which Fig. 22 As shown, the spring struts 216 and the struts 222 of the retaining device 210 are completely flattened on one side. On the opposite side, which is shown in Fig. 22 As shown above, the spring tongues or a spring tongue 216 no longer rest on the shaft section 238 of the screw 236. Even in the state of the Fig. 22 However, the anti-loss device 210 still ensures that the screw 236 cannot be pulled out of the socket 244, in Fig. 22 i.e. to the left, and the loss prevention device 210 is still fixed in the bore of the bushing 244 by the struts 222.

[0091] There are various ways to insert the loss prevention device 210 into the bore of the bushings 234, 244. For example, but not according to the invention, the loss prevention device 210 can first be inserted into the bore of the bushing 234, 244 without the screw 236. Only then can the screw 236 be inserted into the loss prevention device 210. During this insertion, the spring tongues 216 deflect radially outwards until the thread 240 has passed the spring tongues 216. Then the spring tongues 216 spring back inwards into the Fig. 20 oder 21 shown position.

[0092] Alternatively, and according to the invention, the captive device 210 can also first be pushed onto the shaft of the screw 236. To do this, the screw 236 is simply inserted into the captive device 210 from the end 228. The spring tongues 216 then deflect radially outward and then spring back inward once the thread 240 of the screw 236 has passed the spring tongues 216. Together with the screw 236, the captive device 210 can then be pushed into the bore of the bushing 234, 244 and positioned.

[0093] The loss prevention device 210 can also be called a spring tongue sleeve.

[0094] In the design of the Fig. 20 bis 22The spring tongues 216 of the anti-loss device 210 rest on the thread-free and smooth shaft section 238. A loss-prevention device can also be achieved by the spring tongues 216 resting on the thread of a screw, and the screw can, for example, also have a circumferential groove on its shaft into which the spring tongues 216 can then engage.

Claims

1. Securing means (210) for a screw having an annular sleeve for insertion in a through-hole in a workpiece, wherein the annular sleeve is provided with at least one plate-like resilient tongue (214) which extends from the annular sleeve and which projects in the direction toward a longitudinal centre axis (218) of the sleeve, characterized in that the at least one plate-like resilient tongue (214) extends from the annular sleeve initially parallel with the longitudinal centre axis (218) of the sleeve, then obliquely relative to the longitudinal centre axis (218) toward the longitudinal centre axis (218) and, at least up to a location just in front of the free end of the plate-like resilient tongue (214), again parallel with the longitudinal centre axis (218), and in that the annular sleeve has an annular cage (220) having a plurality of struts (222), wherein the annular cage (220) can be resiliently compressed in a radial direction in order to fix the securing means (210) in a hole.

2. Securing means according to Claim 1, characterized in that the annular sleeve has a slot which is continuous from a first edge to a second edge.

3. Securing means according to Claim 1, characterized in that the annular sleeve has a portion (212) which forms a closed ring.

4. Securing means according to Claim 1 or 2, characterized in that three plate-like resilient tongues (214), in particular from 3 to 8 resilient tongues (214), are distributed uniformly over the circumference of the annular sleeve.

5. Securing means according to one of the preceding claims, characterized in that, directly in front of the free end thereof, the at least one plate-like resilient tongue extends obliquely relative to the longitudinal centre axis away from it.

6. Securing means according to one of the preceding claims, characterized in that the annular sleeve and the at least one resilient tongue (214) are formed from a high-grade steel plate, from a metal, from a non-ferrous metal, from a plastics material or from a hybrid material.

7. Securing means according to at least one of the preceding claims, characterized in that the at least one resilient tongue extends from a first edge of the sleeve and in that the sleeve is provided in the region of a second edge which is opposite the first edge with at least one projection which projects radially outwardly away from the longitudinal centre axis.

8. Securing means according to at least one of the preceding claims, characterized in that the annular sleeve is bent from a band-like material strip.

9. Securing means according to Claim 8, characterized in that an intermediate space is located between the beginning and the end of the material strip made of sheet metal in the finished state of the annular sleeve.

10. Securing means according to at least one of the preceding claims, characterized in that the sleeve has a portion (212) which forms a closed ring, wherein, when viewed in the direction of a longitudinal centre axis (218) of the ring, the at least one resilient tongue (214) extends from the portion which forms the closed ring, and wherein a longitudinal extent of the resilient tongue (214) is from one time to three times the length of the portion (212) forming the closed ring.

11. Securing means according to at least one of the preceding claims, characterized in that two resilient tongues (214) which are arranged beside each other in a circumferential direction are separated from each other by means of an incision (216) in the sleeve.

12. Mounting unit having a screw (232), a bush (234) and a securing means (210) according to at least one of the preceding claims, wherein the securing means (210) is inserted in the bush (234) and the screw (232) extends at least partially into the bush (234) and is retained in the bush (234) by the securing means (210).

13. Mounting unit having a screw (232), a sheet metal component and a securing means (210) according to at least one of the preceding Claims 1 to 11, wherein the securing means (210) and the screw (232) are inserted in a through-opening of the sheet metal component.

14. Method for mounting a screw (232) and a securing means (210) according to one of the preceding Claims 1 to 11 in a hole, wherein initially the securing means (210) is pushed on the shaft of the screw (232) and then the securing means (210) is inserted together with the screw (232) into the hole and positioned.