Contact plug

Abstract

Contact plug (20) for transmitting electrical energy by detachable contact with a contact socket (10), wherein the contact plug (20) has at least one claw-shaped element (50) which deforms due to temperature changes and effect a change in the contact normal force between the contact plug (20) and the contact socket (10), wherein the at least one claw-shaped element (50) has a chamfer in the form of a chamfer F at its extension end.

Description

[0001] The invention relates to a contact plug for the transmission of electrical energy by detachable contact with a contact socket.

[0002] For contacting or creating detachable electrically conductive connections, plug connectors, contact elements, pole connectors, sockets, etc., are used in a wide variety of designs and variants. Particularly, but not exclusively, for electrical contacting tasks in the higher power range, contact systems have been developed that are based on circular contact geometries for receiving a contact pin and whose starting material consists of a planar contact grid that is brought into the circular contact geometry with a hyperbolic twist. These contact systems, known as RADSOK, are characterized by robust and high-density contact formation due to the considerable contact area with the respective contact pin. Alternatively, instead of the hyperbolic twist, inwardly directed lamellar geometries are known, whose lamellar contact grid is radially symmetrical.

[0003] These contact geometries, preferably used as high-current contact sockets, are therefore known as radial contact sockets or hyperbolic contact sockets.

[0004] RADSOK contact systems of the aforementioned type are received into connector socket sleeves via their generally cylindrical outer contours and achieve external contact via the cylindrical surfaces. DE 10 2007 051 266 B4 is based on the fundamental idea of ​​providing a single connector socket sleeve designed to accommodate different lamellar contact cages in the form of RADSOK contact sockets, which make contact with the inside of the contact sleeve.

[0005] A comparable basic structure is shown in DE 20 2016 100 095 U1. The subject matter of the invention here is the coupling, connection, and contacting of the cylindrical lamellar cage "floating" within the receiving connector socket sleeve by fixing only one of the respective end flanges in the socket, for example, by press fit. An electrical connector socket comprising a cylindrical socket sleeve is provided, which is designed with a receiving space in which a cylindrical lamellar cage with a plurality of parallel contact lamellae is inserted, wherein the lamellar cage has a first and second circumferential flange rib at its end, between which the contact lamellae extend. The lamellar cage is fixed at one end at least axially and preferably also rotationally fixed in the socket sleeve and thereby clamped.The lamellar cage is attached to the bushing sleeve and, at the opposite end, has an axial sliding bearing that is rotatable at least through a certain angle. Preferably, the lamellar cage is attached to the inner wall of the bushing sleeve by means of a fastening element on the sleeve side, using a flanged web.

[0006] From documents DE 10 2010 008 112 A1, CH 613 814 A5, GB 2 162 700 A and DE 810 525 B, contact elements are known which have curved contact lips designed to make contact with a correspondingly shaped counter-contact.

[0007] Especially in high-current contact applications—for example, charging batteries in electric vehicles or connecting the vehicle battery to the vehicle's electrical components—reliable electrical contact between the connectors is crucial. Such connectors and their contact elements, which often consist of one or more pairs of pins and sockets, are subject to various influences, such as mechanical stress, vibrations, shocks, and aging. Significant temperature fluctuations, caused by environmental conditions or by self-heating due to the electrical current flow and the inherent resistance of the current-carrying components, are also possible.Self-heating can be particularly relevant at the contact points, as the contact areas are small due to the contact force, resulting in a high resistance almost geometrically induced by the contact. For this reason, it is crucial that the contact force – more precisely, the normal contact force – is as high as possible and remains constant to press the contact partners, usually formed by a contact pin and a contact socket, firmly together at their contact surfaces for electrical connection.

[0008] The contact sockets available in the prior art, such as the aforementioned RADSOK sockets or their plug-in contacts (the plug-in pins), utilize both formative shaping processes such as stamping and rolling, and suitable materials with spring properties to generate the desired spring action through restoring forces. These forces are used to create preferably elastic contact forces between the contact partners at their contact surfaces. The performance of the plug-in connection is limited by temperature effects, as higher temperatures cause a loss of spring force due to relaxation processes, material creep, and residual stress reduction. This is particularly true for copper and copper alloys, since copper, in addition to its generally low elasticity, becomes "soft" even at low temperatures.

[0009] If the plug contact partners are designed in this way and made from materials such as spring steel, it is indeed possible to generate very high normal contact forces that reliably press the contact surfaces of the plug contact partners together, but assembly problems often arise because plugging the contact partners together requires high insertion forces, which make assembly difficult or require the use of tools.

[0010] To mitigate the problem of decreasing contact normal forces under temperature influence, contacting solutions have been developed in which the contacting elements or additional components deform as a result of the temperature increase, thereby increasing the contact force while simultaneously reducing the assembly force required when mating the connector at lower temperatures. EP 2 461 427 B1 discloses a self-deforming high-current contact based on the approach of achieving low mating forces at room temperature for assembly and high contact force or contact normal force during operation, particularly under conditions of increased self-heating and elevated ambient temperatures, through the design of the high-current contact and the provision of a connector element that deforms automatically with rising temperature.

[0011] The contact normal force increases almost automatically as soon as the temperature rises. The proposed high-current contact serves to transmit current from a power source to an electrical conductor of a current collector. Thus, the high-current contact, together with the corresponding contact pin, serves both as a mechanical connection and as an electrical contact between the current collector and the power source via an electrical contact surface between the high-current contact and the contact pin. By increasing the mechanical connection through temperature-induced deformation of the high-current contact or its self-deforming components, particularly a ring-shaped element, as the temperature of the high-current contact rises due to current flow, the material-induced loss of contact normal force is counteracted, and the contact force is at least maintained, and in some cases even increased.At the same time, assembly is possible at low temperatures with reduced insertion force.

[0012] A similar approach is pursued in DE 10 2005 032 462 A1. This patent teaches how to design the contact socket in such a way that at least the area of ​​the contact tips consists of a bimetallic strip. The area made of the bimetallic strip changes its shape due to the influence of heat. This change in shape is used to at least keep the contact normal force constant or to increase it.

[0013] The contact solutions available in the prior art, which involve temperature-dependent changes in the contact normal force and are constructed using a combination of contact socket and contact pin, exhibit some significant disadvantages. Solutions often incorporate one or more components, such as rings or tubular parts, which influence the contact normal force due to temperature changes. These solutions are complex, require multi-part contact assemblies, are therefore more difficult to assemble, and have a higher potential for assembly errors. This results in economically unfavorable solutions and increases the likelihood of malfunctions.

[0014] Other contact designs integrate the temperature-deforming components of the contact or connector into the contact socket component. With such geometric designs, the temperature-dependent deformation can only influence and, in particular, increase the contact normal forces to a comparatively small extent. Furthermore, the heating process of the integrated deformation components can take a considerable amount of time – this is due to their being integral with the contact element.

[0015] The object of the invention is to further develop existing contacting solutions with contact normal forces that can change due to temperature influence and to at least partially reduce the existing disadvantages.

[0016] To solve this problem, the invention proposes a contact connector with the features of claim 1. The at least one claw-like element extends from a base element, which has a continuously continuous and largely linear shape with a flat or slightly curved cross-section in the insertion direction, in a certain area, such that the contact pin does not have a closed, cylindrical overall contour and the at least one claw-like element is deformable at its end. Preferably, the invention provides for two or more claw-like elements. Functionally, the base element in this case is practically similar to the vertebral column of the human skeleton, in which the ribs (here: claw-like elements) are attached and extend transversely to the direction of vertebral extension.

[0017] The claw-shaped elements, with their arc-like form extending circumferentially in certain areas, form sections of a cylindrical outer contour of the contact pin and have a constant or changing radius in the circumferential direction. A radius that decreases towards the end of the claw-like elements is particularly advantageous, so that the arc-like shape of the claw-like elements essentially curls up. In this way, the deformation behavior of the claw pin, made of multilayer metal or a shape-memory alloy, and the resulting contact normal force, caused by temperature changes, can be additionally influenced geometrically.

[0018] The invention provides for a further, geometrically determined influence on the temperature-change-induced contact normal force through deformation of the spring-elastic, claw-shaped elements made of a multilayer metal or a shape-memory alloy by means of unequal widths. The width of the claw-shaped elements, i.e., their extent in the insertion direction (axial direction of the contact pin) and thus transverse to the claw-shaped, arc-like form, can increase from the first claw-shaped element arranged in the insertion direction to the subsequent claw-shaped elements located behind it in the insertion direction. This results in a width-dependent difference in the deformation behavior of the claw-shaped elements, because claw-shaped elements with a smaller width are subject to faster temperature changes due to their smaller overall mass under the same heat energy input.As a result, a change in contact normal force is achieved at different times due to the effect of the multilayer metal structure or the shape memory alloy and the resulting deformation.

[0019] At the end of the contact pin opposite the insertion direction, a protruding section of the base element can be provided as a functional element, which can be used for crimping (e.g., crimping or welding) an electrical line, cable or as a handle in the sense of a handling aid.

[0020] According to the invention, at least the claw-shaped elements or even the entire contact pin are made of a multilayer metal material, which, for example, is constructed as a bimetal from two different material types. It is advantageous to form the outer region of the claw-shaped elements or the contact pin, with its contact surfaces facing the contact bushing, from a copper material, and to construct the inner region, i.e., the regions of the claw-shaped elements or the contact pin facing away from the contact bushing, from a steel material. Since the copper material and the steel material exhibit different thermally induced expansion behaviors, the bimetallic material deforms and causes a deformation of the claw-shaped elements, which is used to influence the contact normal force.Layer structures with three materials can also be realized, in which the middle layer consists of a copper material, thus ensuring that the multilayer metal arrangement has good electrically conductive properties.

[0021] In a further embodiment, it is provided that the temperature-dependent deformation required to change the contact normal force is achieved by using a shape memory alloy (also called memory metals) for the contact pin or for at least its claw-shaped elements.

[0022] According to the invention, it is possible for the at least two claw-shaped elements to be part of the contact socket instead of the contact plug. It is also possible for both the contact socket and the contact pin / plug to have claw-like elements. The descriptions in the text apply analogously to these embodiments as well.

[0023] The invention offers several advantages. Most notably, only low insertion forces are required when connecting the contact partners, consisting of a claw pin and a contact socket, at room temperature. This is because the increase in contact normal force only occurs when the claw pin and / or the contact socket heats up, and does not require a spring-like preload. The invention also achieves an increased contact normal force with temperature changes, resulting in a rise in temperature and a corresponding decrease in electrical resistance. Consequently, the increased contact normal force results in high pull-out forces (i.e., the forces required to pull the connector apart) at operating temperature, making such connectors less susceptible to vibration.

[0024] Economic mass production is facilitated by the fact that the geometrically simple contour of the starting material, the semi-finished product, is very well suited for manufacturing by means of a stamping process. Solutions available in the prior art, in particular the so-called Radsok bushings, are very fine and feature a large number of lamellae, which have a long stamping edge and require high stamping force.

[0025] The invention is explained in more detail below with reference to an exemplary embodiment in conjunction with the figures. These show: Fig. 1 the perspective view of the contact plug, which according to the invention is designed as a claw pin; Fig. 2 the perspective view of the claw pin in a opposite Fig. 1. differing direction of view; Fig. 3 the side view of the claw pin; Fig. 4 the perspective view of the contact partners for an electrically conductive plug connection; Fig. 5. The three-dimensional view of the contact partners for an electrically conductive plug connection; Fig. 6 the spatial representation of the claw pin directed towards the end in the insertion direction.

[0026] Fig. Figure 1 shows a perspective view of the contact connector, which according to the invention is designed as a claw pin 20. The claw pin comprises at least two constructive-geometric elements that characterize the claw pin 20: a base element 30 and at least one claw-shaped element 50. Optionally, the claw pin 20 can be supplemented by at least one functional element 40.

[0027] The base element 30 functionally forms the backbone of the claw pin 20. Viewed in the insertion direction and largely parallel to the insertion axis, it forms a continuously continuous and largely linear shape with a flat or slightly curved cross-section, from which at least one claw-shaped element 50 extends in the circumferential direction of the claw pin 20 and thus transversely to the insertion direction.

[0028] The at least one claw-shaped element 50 extends circumferentially around the claw pin 20 and forms a section of the cylindrical contour of the contact connector. In the section plane axial to the claw pin 20, the at least one claw-shaped element 50 has one or more different radii of curvature R, R1, R2. Preferably, two claw-shaped elements 50, located at a largely identical axial height around the claw pin 20, extend circumferentially.

[0029] An optional functional element 40 can supplement the claw pin assembly. The functional element 40 can extend in the opposite direction to the insertion direction and be designed as an extension of the base element 30. It can have a bore, tabs, or other geometries suitable for providing additional functions, such as a grip to assist handling when connecting the contact or plug-in partners, consisting of contact socket 10 and claw pin 20, or for attaching a cable or wire (possibly with shielding) by, for example, welding or crimping.

[0030] Fig. 2 includes the perspective view of the claw pin 20 in a contrasting Fig. 1. Different viewing direction. Shown is the optional configuration of a plurality of claw-shaped elements 50, which are arranged in pairs opposite each other and mirror-symmetrically to each other at an axial height of the claw pin 20.

[0031] The claw width b is varied here in the qualitative manner shown such that the width of the claw-shaped elements 50 can have two or more different values ​​relative to each other. It is particularly advantageous to provide a width b of the first pair of claw-shaped elements 50 arranged in the insertion direction with a width b1 and to realize a width b2 of the second pair of claw-shaped elements 50 arranged in the insertion direction, where b1 <b2 ist. Das Breitenverhältnis kann beliebig variiert oder über mehrere krallenförmige Elemente 50 konstant gehalten werden.

[0032] A width b1 is particularly advantageous <b2<bn des oder der mehreren ersten Paare von krallenförmigen Elementen 50, die in Steckrichtung zuerst angeordnet sind. Infolge der geringeren Masse dieser schmaleren krallenförmigen Elemente 50 gegenüber der in Steckrichtung dahinterliegenden Krallenpaare sorgt nach dem Zusammenstecken der Kontaktpartner und des elektrischen Widerstandes bei Anlegen einer elektrischen Spannung für ein schnelleres Erwärmen dieser schmaleren krallenförmigen Elemente 50. Auf diese Weise kann eine erste Kontaktnormalkrafterhöhung frühzeitig und unmittelbar nach Beginn des Stromflusses realisiert werden.Depending on the material used – multilayer metals in the form of copper-steel combinations or shape-memory alloys – it has been shown that the width ratio b1 / b2 of the first pairs of claw-shaped elements 50, which are arranged first in the insertion direction, relative to the claw pairs located behind them in the insertion direction, is particularly advantageous in a range of 0.3 ≤ b1 / b2 ≤ 0.8 and preferably approximately 0.5. These width ratios can be implemented in pairs or over several pairs of claw-shaped elements 50 with mutually identical width ratios (groups of equal claw width).

[0033] Fig. Figure 3 illustrates the side view of the claw pin 20 from the viewing direction opposite to the insertion direction, i.e., towards the contact plug end in the direction of the contact socket 10. Starting from the base element 30, the two claw-shaped elements 50 shown here as an example extend in a parallel and mirror-symmetrical manner and form at least partially a cylindrical contour of the claw pin 20 with an opening OE opposite the base element 30.

[0034] The opening OE can optionally also be used as an anti-rotation device for the claw pin 20 within the contact socket 10 when inserted. For this purpose, a spring (not shown) can be provided in the contact socket, which engages in the opening OE and thus prevents rotation by means of a mechanical stop.

[0035] The claw-shaped elements 50 extend circumferentially around the claw pin 20 and have a circular arc-like shape. The circular curvature of this embodiment of the claw-shaped elements 50 is not constant in the direction of extension from the base element 30; that is, the radius of curvature R decreases, at least in some areas, as the extension progresses away from the base element, such that R1 > R2. The reduction in radius can be continuous – as shown – or exhibit abrupt changes in radius. The configuration R2 <R1 ist neben der Werkstoffwahl und der Temperaturänderung eine zusätzliche und geometrisch bedingte Einflussmöglichkeit auf die Änderung und Erhöhung der Kontaktnormalkraft durch Temperaturänderungseinwirkung.

[0036] As a result of the change in radius, the deformation behavior of the claw pin 20, which consists of multilayer metal or a shape memory alloy, triggered by temperature changes, can be additionally influenced geometrically, and the locally varying deformation of the claw-shaped elements 50 can be used to adjust and increase the resulting contact normal force. A radius ratio of 1.1 ≤ R1 / R2 ≤ 3 is particularly advantageous for multilayer metals, especially bimetallic structures, as well as shape memory alloys.

[0037] Fig. Figure 4 shows a perspective view of the contact partners 1 for an electrically conductive connector, here consisting of a claw pin 20, which is at least partially inserted into a contact socket 20. Due to the temperature-induced increase in the contact normal force, the contact normal force does not need to be generated, or only needs to be generated to a reduced extent, by the elastic deformation of the contact partners before the temperature effect. This makes inserting the claw pin 20 into the contact socket 10 easier and more convenient for assembly.

[0038] Fig. Figure 5 shows a three-dimensional view of the contact partners 1 for an electrically conductive plug connection in the insertion direction. The claw-shaped elements 50 are designed with a significant clearance relative to the contact socket at their extension end and adjacent to the opening OE at assembly temperature, which is preferably equal to the ambient temperature, thus facilitating assembly.

[0039] Fig. Figure 6 shows the spatial representation of the claw pin 20, which is oriented towards the end facing the insertion direction. This detailed view shows the optional chamfer or bevel F, which can be implemented on one or more claw-shaped elements 50. The bevel F is located on the insertion-direction side, laterally and at the end of the claw-shaped elements 50. This further facilitates assembly, i.e., the joining of the contact partners 1 by inserting the claw pin 20 into the contact socket 10, because it prevents the pin from catching during insertion. Reference sign 1 contact partner for an electrically conductive plug connection 10 Contact socket 20 contact plugs, claw pins 30 Basic element 40 Functional element 50 claw-shaped elements b, b1, b2, bn Claw width, width of the claw-shaped element F chamfer, bevel OE opening R, R1, R2 radius of curvature claw-shaped element

Claims

[1] Contact plug (20) for transmitting electrical energy by detachable contact with a contact socket (10), wherein the contact plug (20) has at least one claw-shaped element (50) which deforms due to temperature changes and realizes a change in the contact normal force between the contact plug (20) and the contact socket (10), wherein the at least one claw-shaped element (50) has a chamfer in the form of a chamfer F at its extension end. [2] Contact plug (20) according to claim 1, characterized by , that at least one claw-shaped element (50) extends from a base element (30) in a circular arc with a radius of curvature R in the circumferential direction of the contact plug (20). [3] Contact plug (20) according to claim 2, characterized by, that at least one claw-shaped element (50) extending from the base element (30) has a first radius of curvature R1 and a second radius of curvature R2 at the end of the extension. [4] Contact plug (20) according to claim 3, characterized by , that the radius of curvature R1 is larger than the radius of curvature R2 and the radius ratio lies in a range 1.1<=R1 / R2<=3. [5] Contact plug (20) according to claim 2, characterized by , that at least a second claw-shaped element (50) extends in a circular arc from the base element (30) and is arranged such that it is arranged in the axial direction of the contact plug (20) parallel and mirror-symmetric to the first claw-shaped element (50), so that a pair of claws is formed which section by section forms a cylindrical outer contour of the contact plug (20). [6] Contact plug (20) according to claim 5, characterized bythat the pair of claws has an opening OE. [7] Contact plug (20) according to claim 1, characterized by , that a plurality of claw-shaped elements (50) are arranged in the axial direction of the contact plug (20). [8] Contact plug (20) according to claim 7, characterized by , that the majority of the claw-shaped elements (50) have one or more different claw widths b. [9] Contact plug (20) according to claim 8, characterized by , that the different claw widths b between two claw widths b1, b2 lie in a ratio of 0.3<=b1 / b2<=0.

8. [10] Contact plug (20) according to claim 1, characterized by , that at least one claw-shaped element (50) is formed from a multilayer material or a shape memory alloy with the property of undergoing a change in shape by changing the temperature. [11] Contact plug (20) according to claim 2, characterized by, that the base element (30) has a functional element (40) at its end opposite to the insertion direction of the contact plug (20).

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