Insert for connecting an electrical connection to a wall, and protective cap for an insert.

Description

[0001] The invention relates to an insert for connecting an electrical connection to a wall, for example a thin sheet metal, with a bolt having a shaft which is provided with a connecting means, and an electrically conductive ring with a through-opening for receiving the bolt, wherein the received bolt protrudes with its shaft from a contact surface of the ring.

[0002] To establish electrical conductivity between a cable and a metal sheet, it is known to attach a bolt (grounding bolt) to the sheet using a deformable sleeve or ring. The ring typically has a contact surface for the electrical connection of a cable, and the bolt has a connecting element, such as a threaded shank, for securing the cable. This shank protrudes from the contact surface of the ring, so that when the cable is attached with the connecting element, it is pressed onto the contact surface. The connection between the ring and the sheet must be able to withstand tensile forces and torque, which can be generated, for example, when a cable lug is attached to the bolt with a nut. This is achieved through radial expansion and increased surface pressure in the area of ​​the metal sheet.Additionally, the sleeve expands outside the sheet metal, allowing for increased tensile strength. Current is transferred across the walls of the bore in the sheet metal. The installation and shaping of the sleeve must ensure that the contact resistance in this area is as low as possible.

[0003] From EP 0 880 199 B1, an insert of the type mentioned above is known, comprising a bolt and a ring. The bolt has a head extending along a first longitudinal axis and a shank provided with at least one connecting element. The ring has a through-opening for receiving the bolt, extending along a second longitudinal axis. The head of the bolt is approximately shaped like a truncated cone, which widens the cylindrical through-opening of the ring when the head is drawn into the ring.

[0004] If such an insert is mounted on a wall, the bolt protrudes unprotected and exposed. Subsequent work on this wall poses a risk of damage to the bolt, for example, to its threads. In particular, walls, such as sheet metal components, must be painted after a bolt is installed. If, for example, paint is accidentally applied to the bolt's threads, the bolt can later no longer be connected to a cable, or only with considerable effort. If the contact surface of the ring is accidentally painted, this leads to increased contact resistance between the cable and the wall, as paints generally have electrically insulating properties. At high currents, this can cause significant heating of the insert and the wall, which can lead to damage to the wall.Depending on the area of ​​application, this can even lead to a significant fire risk, which must be avoided.

[0005] US Patent 7,892,049 discloses an insert with a threaded bolt and nut for connecting electrical terminals to a vehicle wall. The nut can be replaced by a protective cap.

[0006] Further protective caps for protecting a connection between bolt and nut are known from DE 30 33 714 A1 and US 5,590,992 A.

[0007] It is therefore an object of the present invention to provide an improved insert that offers protection during work, in particular during painting.

[0008] This problem is solved by an insert with the features of claim 1. The insert according to the invention for connecting an electrical terminal to a wall has a bolt with a shank that includes a first connecting element. The connecting element can be, for example, a thread, a bayonet fitting, a cross pin, or another fastening element. The insert according to the invention further comprises an electrically conductive and cylindrical ring with a through-opening for receiving the bolt, wherein the received bolt protrudes with its shank from a surface of the ring, which thus forms the contact surface of the ring. According to the invention, the insert also includes a protective cap with a retaining section having a second connecting element that can be connected to the first connecting element of the bolt, and a flange section that rests against the contact surface of the ring when the protective cap is connected.

[0009] According to the invention, the protective cap completely covers the shaft and the contact surface of the ring. This protects the relevant areas of the insert from damage and / or accidental application of paint.

[0010] In a preferred embodiment of the invention, the first connecting element and the second connecting element are arranged such that the connection of the first connecting element with the second connecting element presses the flange section of the protective cap against the contact surface of the ring. The contact pressure ensures a tight connection of the protective cap, thereby preventing liquids, such as varnish or paint, from flowing between the protective cap and the insert and thus from reaching the contact surface or the shaft despite the protective cap.

[0011] In a preferred embodiment of the invention, the flange section is essentially disc-shaped and has a top surface facing the retaining section and a bottom surface facing away from the retaining section, the bottom surface resting against the contact surface of the ring when the protective cap is connected to the bolt. Since the retaining section is directly connected to the shaft and the flange section lies flat against the contact surface, the insert protected by the protective cap occupies very little space. This embodiment is therefore particularly suitable for confined spaces. In particular, the second connecting element in the retaining section can be designed as a clamping cylinder whose inner diameter corresponds to the outer diameter of the shaft. The retaining section, and therefore the protective cap, is thus connected to the bolt solely by frictional forces.Since the retaining section extends essentially over the entire length of the protective cap, the cap is reliably held on the shaft. In this design, the protective cap can be connected to the bolt particularly quickly, as it simply needs to be pushed onto it.

[0012] In a particularly preferred embodiment of the invention, the disc-shaped flange section has an additional clamping ring that projects from its underside. The clamping ring can have its inner diameter adapted to the outer diameter of the shaft so that it is held against the shaft by frictional forces. Alternatively or additionally, the clamping ring can have its outer diameter adapted to the inner diameter of the through-hole of the ring so that it is held against the through-hole. The clamping ring therefore constitutes an additional connecting element for the protective cap.

[0013] In a preferred embodiment of the invention, the flange section is essentially cylindrical and rests against the contact surface of the ring with an end face facing away from the retaining section, which is particularly annular. The cylindrical flange section provides a particularly good grip for connecting the protective cap to the bolt. Additionally, the protective cap is particularly well sealed against the contact surface by the adjacent end face. The second connecting element in the retaining section can, in particular, be designed as an internal thread in the retaining section.Since the retaining section and the threaded section within it do not extend over the entire length of the protective cap, it can be manufactured particularly easily using injection molding. Furthermore, the protective cap does not need to be screwed to the bolt along its entire length, but only along the length of the threaded section.

[0014] In a particularly preferred embodiment of the invention, the protective cap has a chamfer on the inside of the flange section, on its end face facing away from the retaining section. The chamfer is thus located at the edge between the end face and the inside of the cylindrical flange section. This chamfer further reduces the contact area of ​​the flange section on the contact surface, resulting in a higher contact pressure for the same force exerted by the fasteners. This leads to a particularly tight connection.

[0015] According to the invention, a cover ring is arranged on the flange section, which encompasses a lateral surface of the ring. The cover ring ensures, on the one hand, that the flange section is centered on the contact surface, preventing it from being displaced by an external lateral force, which could expose parts of the contact surface. Furthermore, it also protects the lateral surface of the ring from damage.

[0016] According to the invention, the ring has a groove on its outer surface, and the cover ring projects completely over the groove. The groove allows the ring to be gripped with a tool, for example, to carry out repairs on the insert. If the groove is damaged or accidentally filled with varnish or paint, a tool can no longer grip the insert. The cover ring protects the groove from both damage and accidental application of varnish and / or paint. This ensures that the insert can still be accessed with a tool.

[0017] In a preferred embodiment of the invention, the cover ring has a chamfer on its outer surface at the end face facing away from the flange section. The edge between the end face and the outer surface of the cover ring is therefore chamfered. Since the wall is often subsequently painted or coated for corrosion resistance, it must be ensured that this can be done without gaps. The chamfer on the outer surface of the cover ring facilitates access to the edge between the wall and the outer surface of the ring.

[0018] In a preferred embodiment of the invention, the protective cap has a knurled surface on its outer side at the retaining section and / or at the flange section. This serves to improve the handling of the protective cap, so that it can be easily and securely connected to the bolt, for example by screwing it on.

[0019] In a preferred embodiment of the invention, the protective cap with the ring defines a tightly sealed volume, wherein the shaft of the bolt and the contact surface of the ring are arranged within this volume. The protective cap can therefore, for example, spring slightly inwards into the volume upon impact to cushion the force of the impact without causing damage to the insert.

[0020] In a preferred embodiment of the invention, the protective cap is made of a plastic material. Due to its easy deformability, plastic is an excellent material for protecting the insert. Furthermore, it is lightweight and inexpensive to manufacture. The material offers further advantages in painting and coating processes using electrochemical methods. If the protective cap were electrically conductive, it would also be coated uniformly using such methods. With plastic, however, essentially only the part to be coated is painted, since the plastic is not electrically conductive.

[0021] Further features, advantages and possible applications of the present inventions will also become apparent from the following description of exemplary embodiments and with reference to the drawings.

[0022] They show schematically: Figure 1: A side view of a mounted insert without a protective cap; Figure 2: A side view of a protective cap; Figure 3: A side view of an insert according to the invention with a protective cap; Figure 4: An oblique top view of an insert according to the invention with a protective cap; Figure 5: A sectional view of an insert according to the invention with a protective cap; Figure 6: An enlarged detail from the sectional view of an insert according to the invention with a protective cap. Fig. 5 Figure 7: A sectional view of an alternative unstressed insert with protective cap.

[0023] Figure 1Figure 1 shows an insert with a bolt 1 having a head 3 and a shaft 4 extending along a central axis. An external thread 5 is provided on the outer surface of the shaft 4 as a connecting element to connect the shaft 4, and thus the insert according to the invention, to an electrical conductor, for example, by means of a cable lug. The cable lug is then pressed onto a contact surface 11 of the ring 2, which is electrically conductive and thus establishes an electrical connection to the wall 10 via the ring 2. The ring 2 is inserted into an opening in the wall 10 and has a through-opening 6 into which the bolt 1 with its head 3 is pressed. The through-opening 6 is slightly smaller than the outer diameter of the head 3 of the bolt 1. This causes the ring to expand when the head 3 is pressed in, thus firmly connecting it to the wall 10.The ring 2 has a sleeve section 7, which is essentially cylindrical and is inserted into the opening of the wall 10. Another cylindrical section of the ring 2 has a larger outer diameter and is designed as a shoulder 8, which abuts an outer surface of the wall 10. A groove 9 is also arranged in the outer contour of the shoulder 8, which completely encircles the ring 2 and is designed to engage a tool. The shank 4 of the insert protrudes from the wall 10 and is therefore susceptible to damage.

[0024] Figure 2Figure 1 shows a protective cap 20 of an insert according to the invention, comprising a retaining section 21 and a flange section 22. Both the retaining section 21 and the flange section 22 are essentially cylindrical and connected to each other at a joint. The retaining section 21 has a smaller outer diameter than the flange section 22, with the joint being concave and tapering from the large diameter of the flange section 22 to the small diameter of the retaining section 21. An internal thread 26 is provided on the inside of the retaining section 21 as a second connecting element. On the underside of the flange section 22, which faces away from the retaining section 21, the flange section 22 has a cover ring 23. The cover ring 23 is provided with a chamfer 24 at the edge between its underside and the outside of the cylindrical surface.To connect the protective cap 20 to the bolt 1 and ring 2 inserted in the wall, the protective cap 20 is positioned over the bolt 1 and the internal thread 26 of the protective cap is screwed to the external thread 5 of the bolt 1.

[0025] Figure 3 Figure 1 shows the complete assembly according to the invention, wherein the protective cap 20 is screwed to the bolt 1 and the ring 2. The contact surface 11 of the ring 2 and the bolt 1 with its shaft 4 with external thread 5 are completely covered by the protective cap 20. The cover ring 23 surrounds a cylindrical surface of the ring 2, the axial extent of the cover ring being selected such that the groove 9 in the cylindrical surface of the ring 2 is also covered by the cover ring 23.

[0026] The illustration of the application according to the invention in the Figure 4shows that the protective cap 20 and in particular its retaining section 21 is closed at the top and therefore a closed volume is formed by the protective cap 20 and the ring 2 in which the contact surface 11 of the ring 2 and the bolt 1 are arranged, so that they are no longer accessible from the outside.

[0027] Figure 5 and the enlarged view in Fig. 6Figure 1 shows a sectional view of the insert according to the invention. The sleeve section 7 of the ring 2 is inserted into an opening in the wall 10 and pressed into the sleeve section 7 of the ring 2 and into the wall 10 by pressing the head 3 into it. The protective cap 20 is screwed to the upper end of the external thread 5 of the shaft 4 via its retaining section 21 and its internal thread 26. The retaining section 21 has a substantially cylindrical shape, is closed at the top, and is connected to the flange section 22 at the bottom. The flange section 22 rests with its end face 27 on the outer edge of the contact surface 11 of the ring 2. The length of the protective cap 20, the arrangement of the internal thread 26 and the length of the shaft 4 with the external thread 5 are chosen such that the end face 27 already rests on the contact surface 11 when the protective cap 20 with its internal thread 26 is not yet fully screwed onto the external thread 5 of the bolt 1.A further screw connection therefore exerts a force on the contact surface 11 from the end face 27, thus tightly connecting the protective cap 20 to the ring 2. Since the end face 27 has a chamfer 28 at its edge with the inside of the flange section 22, the contact area between the end face 27 and the contact surface 11 is reduced, thereby increasing the contact pressure. The annular contact area between the end face 27 and the contact surface 11 has a width that is smaller than the wall thickness of the flange section 22. This ensures that the protective cap is tightly connected to the ring. The end face 27 of the flange section 22 transitions into the cover ring 23, which surrounds the outer surface of the ring 2 and covers a groove 9 in the outer surface. The cover ring 23 has a chamfer 24 at the edge between its underside and its outer surface.This ensures that the corner between wall 10 and ring 2 remains easily accessible and can therefore be painted.

[0028] An alternative, unclaimed example of the 20' protective cap is in the Figure 7This is shown. It also has a retaining section 21', which, however, extends essentially over the entire length of the bolt 1 up to the contact surface 11. The flange section 22' consists only of a disc-shaped element, the entire underside of which is pressed onto the contact surface 11 of the ring 2. A cover ring 23' with a chamfer 24' is arranged on the outer edge of the disc-shaped flange section, encompassing the outer surface of the ring 2. A clamping ring 29 is also arranged on the underside of the flange section 22', the inner diameter of which is adapted to the outer diameter of the bolt 1. Additionally, the outer diameter of the clamping ring 29 is adapted to the inner diameter of the through-opening 6 of the ring 2. This also holds the protective cap to the ring 2. The retaining section 21' of the protective cap consists only of a clamping cylinder as a second connecting element.This means that the inner diameter of the retaining section 21' is selected such that it rests against the outside of the bolt 1. The protective cap is held on the bolt by the friction between the thread of the bolt 1 and the retaining section. The protective cap can then be placed onto the bolt 1. Reference symbol list

[0029] 1 Bolt 2 Ring 3 Head 4 Shank 5 External thread 6 Through opening 7 Sleeve section 8 Shoulder 9 Groove 10 Wall 11 Contact surface 20, 20' Protective cap 21, 21' Retaining section 22, 22' Flange section 23, 23' Cover ring 24, 24' Chamfer Cover ring 25, 25' Serration 26 Second fastener 27 End face 28 Chamfer End face 29 Clamping ring

Claims

1. Insert for connecting an electrical connection to a wall (10) comprising a bolt (1) with a shaft (4) comprising a first connecting means (5), and an electrically conductive and cylindrical ring (2) having a through-opening (6) for receiving the bolt (1), wherein the received bolt (1) with its shaft (4) protrudes from a contact surface (11) of the ring (2), wherein the insert comprises a protective cap (20, 20'), wherein the protective cap comprises a retaining portion (21, 21') with a connecting means (26), which can be connected to the first connecting means (5) of the bolt (1), wherein the protective cap comprises a flange portion (22, 22'), which, when the protective cap (20, 20') is connected, abuts the contact surface (11) of the ring (2), wherein the protective cap (20, 20') completely covers the shaft (4) and the contact surface (11) of the ring (2), and wherein on the flange portion (22, 22') a cover ring (23, 23') is arranged, which encompasses a groove (9) provided on a lateral surface of the ring (2), such that the cover ring (23, 23') projects completely over the groove (9), characterized in that the electrically conductive ring (2) is deformable and comprises a sleeve portion (7), wherein the sleeve section (7) is adapted to be inserted into an opening of a wall (10).

2. Insert according to claim 1, characterized in that the first connecting means (5) and the second connecting means (26) are arranged such that the flange portion (22, 22') of the protective cap (20, 20') is pressed against the contact surface (11) of the ring (2) by the connection of the first connecting means (5) and the second connecting means (26).

3. Insert according to any one of the preceding claims, characterized in that the flange portion (22') is substantially disc-shaped and abuts the contact surface (11) with an underside facing away from the retaining portion (21').

4. Insert according to claim 3, characterized in that the disc-shaped flange portion (22') comprises an additional clamping ring (29) projecting from the underside of the flange portion (22'), wherein the clamping ring is in particular adapted to an outer diameter of the shaft with its inner diameter and / or is adapted to an inner diameter of the through-opening of the ring with its outer diameter.

5. Insert according to any one of claims 1 to 2, characterized in that the flange portion (22) is substantially cylindrical and abuts the contact surface (11) of the ring (2) with an end face (27) facing away from the retaining portion (21).

6. Insert according to claim 5, characterized in that the protective cap (20), on the flange portion (22), has a chamfer (28) on the inner side of the protective cap (20) on its end face (27) facing away from the retaining portion (21).

7. Insert according to any one of the preceding claims, characterized in that the cover ring (23, 23') has a chamfer (24, 24') on its end face facing away from the flange portion (22, 22').

8. Insert according to any one of the preceding claims, characterized in that the protective cap (20, 20') has a ribbing (25,25').

9. Insert according to any one of the preceding claims, characterized in that the protective cap (20, 20') together with the ring (2) delimits a sealed volume, wherein the shaft (4) of the bolt (1) and the contact surface (11) of the ring (2) are arranged within the volume.

10. Insert according to any one of the preceding claims, characterized in that the protective cap (20, 20') comprises a plastic material.