screw contact

Abstract

Screw contact (100) for connecting an electrical conductor, comprising a metallic housing (110), having a terminal opening (111) for inserting the electrical conductor to be connected, having a pressure piece (120), wherein the pressure piece (120) is received in the housing (110) and is movably held on the housing (110) for narrowing and opening the terminal opening (111), and having a screw (130) for moving the pressure piece (120), wherein the metallic housing (110) has a screw brake (112) which has a tab (113, 114) resting on a thread (131) of the screw (130).

Description

The invention relates to a screw contact for connecting an electrical conductor.Such screw contacts serve to clamp electrical conductors. It may occur that the position of the screw changes during transport due to vibrations. The screw contacts therefore engage partially in the open position and partially in the closed state at the customer or at the installation site. The assembly effort is thereby increased and there is a requirement to enable a screw contact to be delivered in a defined open position.Furthermore, there is the requirement that the screw contact can be opened and closed repeatedly without destruction under substantially the same exertion of force and the clamping mechanism accordingly enables clamping conditions which can be reproduced in a reproducible manner in a repeatable manner. For this purpose, the friction conditions within the clamping device should remain substantially constant even after several repetitions of opening and closing.In DE 89 04 299 U, a lug acting as a screw brake is formed on an insulating holder, wherein this insulating holder is formed from an insulating material (cast plastic).DE 38 02 393 C2 discloses a screw brake in that an omega-shaped bent brake spring is placed on a screw.It is known from DE 20 2004 002 779 U1 to provide a clamping sleeve as a screw brake, which clamping sleeve has to be provided as a separate component in the screw contact, in particular on the screw itself.The object of the invention is therefore to provide a screw contact which at least partially fulfills the above requirements and in particular enables reliable transport securing of the screw and reproducible clamping conditions.The object is achieved according to the invention with the features of the independent claim. Practical embodiments and advantageous refinements of the invention are specified in the dependent claims and the description below.The invention relates to a screw contact for connecting an electrical conductor, having a metallic housing, having a clamping opening for inserting the electrical conductor to be connected, having a pressure piece, wherein the pressure piece is accommodated in the housing and is held movably on the housing for narrowing and releasing the clamping opening, and having a screw for moving the pressure piece. The screw contact is characterized in that the metallic housing has a screw brake which has a tab resting against a thread of the screw.The tab enables a defined screw position in the open position and specifies a defined, at least necessary torque for moving the screw from the open position into a clamping position and from the clamping position into the open position. The tab therefore allows constant friction conditions and torques during the opening and closing of the screw due to the predefined clamping force, so that clamping conditions are reproducible with repeat precision. The screw brake has at least one lug. However, it can also have more than one tab.In particular, it is provided that the tab can bear elastically braced in a spring-loaded manner against the thread of the screw.The tab may be formed by punching out on the metallic housing. The tab can accordingly be formed in particular integrally with the metallic housing and can be an integral component of the metallic housing. The tab can thus be manufactured in a simple and cost-effective manner.According to an advantageous development of the screw contact, it is provided that the tab can be at a distance from a screw head of the screw for each screw-in position of the screw. The tab is then preferably configured and provided exclusively for contact with the thread of the screw. In comparison with a screw securing means acting in the region of the screw head, defined clamping and frictional forces can thus be preset for each position of the screw and during the rotation of the screw.It can be provided that the tab can engage in the thread or bear against the thread by a front edge which is formed between an end face and a side face of the tab. The end edge together with its adjoining surfaces is therefore guided in the thread turn of the screw in particular during a screwing process and can thus also exert a defined clamping force on the screw shank and the thread formed thereon during the rotation of the screw.The tab can in particular be bent at least in sections in the direction of the screw. By the degree of curvature or bending of the tab, the corresponding clamping force in contact with the thread can be adjusted.According to an advantageous development of the screw contact, it is provided that the screw brake of the metallic housing has a further tab which abuts the thread of the screw. Thus, the screw brake can have not only one lug, but a first lug and a second lug.It is preferably provided that the first and the second tab can be arranged opposite one another and can enclose the thread of the screw on two sides. In particular, in this way, a symmetrical application of force of the clamping force of the screw brake to the screw can be effected by the two opposing lugs.The second tab can be formed identically to the first tab, wherein the first and the second tab can be formed in particular mirror-symmetrically to a plane comprising the screw axis.In order to define or preset a clamping force, it can be provided that the first and the second tab limit an opening width which is smaller than the maximum thread diameter of the screw.In particular, it can be provided that the first and the second tab, in an open position of the screw, engage the screw at its end facing away from the screw head or the end of the thread on the end side and can form a stop against which the thread can abut. During screwing in, the brackets can be driven apart in particular at least partially by the screw shaft and the thread, wherein the clamping force of the brackets can be increased in particular by their elastic deformation.It can be provided that the screw can abut the pressure piece with an end facing away from the screw head, in particular a pin. The screw can therefore be in direct contact with the pressure piece in order to be able to convert a screwing-in of the screw into a narrowing of the clamping opening by the pressure piece. In particular, it can be provided that the pressure piece has an eccentric which is held pivotably on the metallic clamping housing.The screw contact can be designed as a front screw connection, wherein the clamping opening and the screw can be arranged on the same housing side of the metallic housing. Thus, for example, it can be provided that the clamping opening can be arranged directly adjacent to the screw projecting out of the housing in the open position.It can be provided that the metallic housing is enclosed by a plastic housing in order to be able to provide insulation to adjacent electrically conductive components.The invention is explained in more detail below with reference to the attached drawings on the basis of a preferred embodiment.They show FIG. 1 shows a schematic, perspective illustration of the screw contact according to an embodiment of the invention with a detail Z and an enlargement V, FIG. 2 shows the screw contact from FIG. 1 in a side view, FIG. 3 shows the screw contact from FIG. 2 in a sectional view along the sectional plane A-A from FIG. 2.FIG. 1 shows a screw contact 100 for connecting an electrical conductor, which is not shown here.The screw contact 100 has a metallic housing 110. The metallic housing 110 has a clamping opening 111 for inserting the electrical conductor to be connected.The screw contact 100 also has a pressure piece 120 or a pressure mechanism formed by the pressure piece 120. The pressure piece 120 is accommodated in the metallic housing 110 and held movably on the housing 110 for narrowing and releasing the clamping opening 111.The screw contact 100 has a screw 130 for moving the pressing piece 120. The metallic housing 110 has a screw brake 112 which has a tab 113 bearing against a thread 131 of the screw 130 and a further tab 114 bearing against the thread 131, so that the tab 113 forms a first tab and the tab 114 forms a second tab.The tabs 113 and 114 are integrally formed on the metallic housing 110 by punching out.Each of the lugs 113, 114 has a distance from a screw head 132 of the screw 130 for each screwing-in position of the screw 130, such that contact between one of the lugs 113, 114 and the screw head 132 cannot occur for any screwing-in position of the screw 130.As is illustrated for the tab 113 by way of example in the enlargement V according to the detail Z in FIG. 1, the tab 113 has a front edge 115 which is formed between a front face 116 and a side face 117 of the tab 113 facing the screw 130. The end edge 115 is provided for this purpose and is configured to engage in the thread 131 of the screw 130 or to bear against the thread 131.The further or second tab 114 is formed symmetrically with respect to the first tab 113.In the open position of the screw 130 shown in FIG. 3, the first tab 113 and the second tab 114 engage around the thread 131 of the screw 130 at the end face and secure the screw 130 in the open position in this way.The brackets 113 and 114 are arranged opposite each other and engage the thread 131 of the screw 130 on two sides. The first and second tabs 113, 114 define an opening width W that is less than the maximum thread diameter D of the screw 130 in the position shown in FIG. 3.When the screw is screwed into a nut thread 140, the lugs 113, 114 are therefore driven apart and displaced laterally, with the result that the clamping force is increased and set to the defined value. In this case, the lugs 113 and 114 are elastically deformed only in a resilient manner, so that a plurality of screwing processes with a defined constant clamping force of the lugs 113, 114 in the direction of the thread 131 is made possible.The screw 130 abuts the pressure piece 120 with an end facing away from the screw head 132 in the form of a pin 133, so that screwing in of the screw is converted into a movement of the pressure piece 120.The screw contact 100 is designed in the present case as a front screw connection 100, wherein the clamping opening 111 and the screw 130 are arranged on the same housing side 118 of the metallic housing 110.List of reference characters100 Screw contact 110 Housing 111 Clamping opening 112 Screw brake 113 Tab 114 Tab 115 End edge 116 End face 117 Side face 120 Pressure piece 130 Screw 131 Thread 132 Screw head 133 Stud 140 Nut thread Z Detail V Enlargement W Opening width D Thread diameter

Claims

Screw contact (100) for connecting an electrical conductor, having a metallic housing (110), having a clamping opening (111) for inserting the electrical conductor to be connected, having a pressure piece (120), wherein the pressure piece (120) is accommodated in the housing (110) and is held movably on the housing (110) for narrowing and releasing the clamping opening (111), and having a screw (130) for moving the pressure piece (120), wherein the metallic housing (110) has a screw brake (112) which has a lug (113, 114) which bears against a thread (131) of the screw (130).Screw contact (100) according to Claim 1, characterized in that the tab (113, 114) is formed on the metallic housing (110) by punching out.Screw contact (100) according to Claim 1 or Claim 2, characterized in that the tab (113, 114) is at a distance from a screw head (132) of the screw (130) for each screwing-in position of the screw (130).Screw contact (100) according to one of the preceding claims, characterized in that the lug (113, 114) engages in the thread (131) or abuts the thread (131) with a front edge (115) which is formed between an end face (116) and a side face (117) of the lug (113, 114).Screw contact (100) according to one of the preceding claims, characterized in that the tab (113, 114) is bent at least in sections in the direction of the screw (130).Screw contact (100) according to one of the preceding claims, characterized in that the screw brake (112) of the metallic housing (110) has a further tab (113, 114) which bears against the thread (131) of the screw (130).Screw contact (100) according to Claim 6, characterized in that the first and second lugs (113, 114) are arranged opposite one another and enclose the thread (131) of the screw (130) on two sides.Screw contact (100) according to claim 6 or claim 7, characterised in that the first and second lugs (113, 114) delimit an opening width (W) which is smaller than the maximum thread diameter (D) of the screw (130).Screw contact (100) according to one of the preceding claims, characterized in that the screw (130) bears against the pressure piece (120) by way of an end (133) facing away from the screw head (132), in particular a pin (133).Screw contact (100) according to one of the preceding claims, characterized in that the screw contact (100) is designed as a front screw connection (100), wherein the clamping opening (111) and the screw (130) are arranged on the same housing side (118) of the metallic housing (110).

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