Screw terminal of the type lift clamp and installation device

Abstract

The invention relates to an under-plug protection part (1) for sliding onto a clamping frame (2) of a screw clamp (3), - wherein the under-plug protection part (1) has the form of a closed frame, which has two opposing longitudinal elements (L1, L2) and a first and a second transverse element (Q1, Q2) which are opposite each other and connect the longitudinal elements to each other, - wherein the first transverse element (Q1) has a through-opening (A) for passing a screw shaft and - wherein a cover apron (S) serving as under-plug protection is formed onto the second transverse element (Q2).

Description

[0001] The present invention relates to a screw terminal and an installation device.

[0002] Installation devices, i.e., electrotechnical components used in distribution boards, which in many cases are mounted on a DIN rail, are usually connected to electrical lines using spring clamps or screw terminals.

[0003] Screw terminals are classified as single-chamber or double-chamber terminals, depending on whether they have one or two clamping chambers. A stripped wire end of an electrical conductor is inserted into a clamping chamber, also called a conductor receiving chamber or simply a chamber, and clamped in place by tightening a screw, also known as a clamping screw.

[0004] Single-chamber clamps, which have a single clamping chamber, are classified as either pressure-piece clamps or elevator clamps. In pressure-piece clamps, when the screw is turned, the screw moves along the screw axis relative to a stationary clamping frame with a pressure piece attached to the screw tip; any terminal connection remains fixed. Pressure-piece clamps are disclosed, for example, in DE8134378U (Siemens AG) dated February 25, 1982, and EP0735614A2 (Weidmüller Interface GmbH & Co.) dated October 2, 1996. In elevator clamps, when the screw is turned, a clamping frame moves along the axis of the screw, while the screw itself does not move axially. Elevator clamps are disclosed, for example, in DE1802558A1 (Woertz, Oskar, Basel, Switzerland) dated July 31, 1968.

[0005] Double-chamber terminals have both a movable pressure piece and a movable clamping frame, both of which can be moved relative to a stationary terminal connection by turning the screw. This allows for an upper chamber between the pressure piece and the terminal connection and a lower chamber between the terminal connection and the underside of the clamping frame. Double-chamber terminals are disclosed, for example, in DE1935560U (Georg Schlegel, Elektrotechnische Fabrik) dated March 31, 1966, and DE3314919A1 (Murr Elektronik GmbH) dated October 25, 1984. KR20060068576A and

[0006] US6172586 discloses a screw terminal with a frame-shaped under-termination guard comprising two opposing longitudinal elements and a first and a second transverse element, which are opposite each other and connect the longitudinal elements. The first transverse element has a through-hole for the passage of a screw shank, and the first transverse element forms a semicircular arc that encloses the through-hole on three sides.

[0007] FR2601513 A1 discloses a screw terminal with an under-plug protection element having a semicircular arc in the first transverse element and a cover apron1 in the second transverse element. FR2601513 A discloses a separation joint which forms the semicircular arc from the first transverse element.

[0008] Double-chamber terminals offer greater convenience than single-chamber terminals because a double-chamber terminal allows for the connection of two conductors with different diameters or one conductor and a busbar. However, double-chamber terminals, like elevator terminals, have the following disadvantage: When the screw terminal is closed, the clamping frame moves upwards, i.e., towards the screw head. This exposes a cavity beneath the clamping frame. Therefore, there is a risk that an installer might insert a conductor end into the cavity below the lower clamping chamber instead of the lower one. This is exacerbated by the fact that the installation area is often poorly lit and not directly visible. The installer may thus mistakenly believe they have inserted the conductor end into the lower clamping chamber when in fact they have inserted it into the cavity below – a so-called under-insertion, incorrect insertion, or behind-insertion.When the screw is tightened, the incorrectly inserted wire end is not clamped; however, it can still touch electrically active parts, which even makes locating the fault with a continuity tester more difficult. If a load current is applied, the high contact resistance due to the lack of contact pressure can then lead to significant heating and thus damage.

[0009] DE 100 18 352 C1 (Siemens AG) dated September 27, 2001, describes a double-chamber clamp in which a skirt is mounted on the clamping frame base to prevent insertion underneath. Lateral notches are provided in the area of ​​the skirt. These create two tabs that are bent inwards and engage beneath the clamping frame base. In this way, the skirt is securely held to the clamping frame.

[0010] DE 10 2016 122 852 A1 (ABB Schweiz AG) dated May 30, 2018, discloses an elevator terminal with a terminal cover that includes an apron serving as a protective cover against insertion. Due to its trough-shaped cross-section with two short end legs and a connecting web linking the two short legs, it is possible to slide the terminal cover with the apron onto the terminal frame even after the frame has already been mounted in a housing half-shell.

[0011] The object of the present invention is an improved under-plugging protection.

[0012] This problem is solved according to the invention by a screw clamp with the features specified in claim 1. The under-insertion protection part of the screw clamp is suitable for sliding onto a clamping frame of a screw clamp. The under-insertion protection part has the form of a closed frame comprising two opposing longitudinal elements and a first and a second transverse element, which are opposite each other and connect the longitudinal elements. The first transverse element has a through-hole for inserting a screw shank. A cover apron serving as under-insertion protection is integrally formed on the second transverse element.

[0013] The invention is based on the finding that a protective insert in the form of a closed frame deforms significantly less, e.g., when an installer touches the cover with a ladder end, than a protective insert that does not have the form of a closed frame; therefore, a protective insert in the form of a closed frame is easier to guide within the housing of an installation device than a protective insert that does not have the form of a closed frame. Thus, snagging or jamming of the protective insert is virtually eliminated.

[0014] Compared to a non-closed frame-type under-mounted protective element, the under-mounted protective element according to the invention, with its symmetrical shape, offers the advantage that forces acting on the frame are transmitted evenly. This results in better guidance of the under-mounted protective element and improved attachment to a clamping frame in which a screw, also known as a clamping screw, is guided in a threaded bore. The secure fit, for example, when an installer bumps the cover apron with the end of a ladder, is better with a symmetrical frame than with an asymmetrical one.

[0015] Furthermore, the closed frame design allows the under-seal protection element to be easily slid onto a clamping frame of a screw clamp. Because the cover apron is integrally formed with the frame of the under-seal protection element, there is no need for a separate retaining contour, such as a tab or hole, on the clamping frame to secure the cover apron. The under-seal protection element according to the invention can therefore be used with several different clamping frames.

[0016] Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0017] According to a preferred embodiment of the invention, the first transverse element forms a ring that encloses the feed-through opening. In this case, the under-mounting protective element must be slid over a clamping frame before the pressure piece is attached to the clamping frame together with the clamping screw. An advantage of this embodiment is that the under-mounting protective element is fixed to the clamping frame by a clamping screw guided in the clamping frame; the tight fit is therefore very stable.

[0018] According to the invention, the first transverse element forms a semicircular arc that encloses the feed-through opening on three sides. The under-mounting protective element can then be slid onto the clamping frame from the side before the pressure piece is mounted on the clamping frame. An advantage of this design is that an under-mounting protective element with a semicircular arc is easier to mount than one with a closed ring. A further advantage of this design is that only an open-close injection mold is required to manufacture the under-mounting protective element, whereas a side slide in the injection mold is required for a variant of the under-mounting protective element in which the first transverse element has a ring enclosing the feed-through opening.

[0019] According to the invention, the semicircular arc has a dividing line in the region of one of its apexes, preferably separating the arc into two equal segments. An advantage of this design is that the underlayment can be mounted on a clamping frame to which a pressure piece is already attached: the ends of the arc segments separated by the dividing line can be bent apart and guided around the pressure piece.

[0020] According to a preferred embodiment of the invention, the cover apron is designed as a plate that lies parallel to the plane defined by the longitudinal and transverse elements. An advantage of this is that the parallel position effectively prevents the clamping chamber of a screw clamp from being inserted underneath.

[0021] According to a preferred embodiment of the invention, at least one spring element is integrally formed on the second transverse element. This spring element is designed such that elastic deformation of the spring element, which occurs when the under-plug-in protective part moves in a direction parallel to the longitudinal elements from the first transverse element to the second transverse element, results in a restoring force in the opposite direction. It is advantageous that the spring element exerts an upward force on the clamping frame, thus creating a fixed position for the clamping frame. The spring elements under the clamping frame ensure that the upper clamping chamber, also referred to as the upper conductor entry opening, remains completely open, and the lower clamping chamber, also referred to as the lower conductor entry opening, remains closed except for a small gap, preferably approximately 1.5 mm, sufficient for the contact tongues of a busbar.This means that the lower clamping chamber of a double-chamber clamp is almost closed and the upper clamping chamber is completely open, just as the installer expects when connecting the device as delivered.

[0022] The screw terminal installed in the installation device is in the following delivery state: The upper chamber of the screw terminal is completely open to allow the insertion of even the thickest conductor ends. The lower chamber of the screw terminal is almost closed: the spring elements, preferably designed as legs, push the clamping frame upwards through their spring force; the clamping frame remains in a position where the spring legs are fully relaxed and the lower conductor entry opening has an opening height of 1.5 mm: this 1.5 mm opening is sufficient for inserting the contact tongues of a busbar. To connect thicker conductors, the installer can use a screwdriver or similar tool to push the clamping frame downwards against the force of the spring legs while turning the clamping screw.

[0023] Another embodiment of the invention is an under-plug protection element manufactured by plastic injection molding. For example, PA66 can be used without glass fiber reinforcement, which gives the under-plug protection element relatively high flexibility.

[0024] The screw clamp of the invention comprises a clamping frame with a head web and a base web, which are opposite each other. The screw clamp has a screw that is screwably mounted in a threaded bore of the head web; this screw is also referred to as the clamping screw. The screw clamp also has a protective insert, as described above. The protective insert surrounds the clamping frame, the opening of the protective insert is aligned with the threaded bore, and the cover of the protective insert projects beyond the base web in the direction away from the head web.

[0025] According to a preferred embodiment of the screw clamp, the head web has a threaded flange on its outer side facing away from the bottom web, which surrounds the threaded bore, wherein the first transverse element of the under-plug protection part has an inner corner on its side facing the second transverse element along the feed-through opening, against which the threaded flange rests.

[0026] According to a preferred embodiment of the screw clamp, the screw clamp is a double-chamber clamp.

[0027] According to a preferred embodiment of the screw clamp, the under-mounting protective element sits on the clamping frame such that the two longitudinal elements of the under-mounting protective element divide the side parts of the clamping frame, which extend between the top and bottom webs, into approximately equal contact surfaces. The side parts of the clamping frame connect the top and bottom webs of the clamping frame at their ends, thus forming the clamping frame together with the top and bottom webs. When viewed from the front, the two longitudinal elements of the under-mounting protective element run approximately along a line that bisects the side parts of the clamping frame from the top and bottom webs.The crucial factor is not that the longitudinal elements of the under-clamping protection element run exactly along the vertical center line of the clamping frame's side panels, but rather that the clamping frame's side panels each have a contact surface adjacent to their outer edges. It is advantageous that a screw torque, generated by turning a screw to move the clamping frame and the pressure piece, can be transferred to the installation device's housing via the clamping frame's contact surfaces; otherwise, i.e., if this screw torque were transferred to the installation device's housing via the longitudinal elements of the under-clamping protection element, there is a risk that the resulting increased friction between the under-clamping protection element and the housing would adversely affect the movement of the screw terminal.The symmetrical positioning of the under-plug protection part on the clamping frame creates approximately equally sized contact surfaces on the outer sides of the side parts of the clamping frame.

[0028] Another embodiment of the invention is an installation device with a screw terminal, as described above. The installation device can be divided into two housing halves. Before the two housing halves are joined, the screw terminal can be inserted into one of the two housing halves. The installation device can be any device that has screw terminals for receiving and securing the conductor ends of electrical cables. In particular, the installation device can be an installation switching device such as an air circuit breaker, arc fault detection device, arc fault circuit interrupter, circuit breaker, electronically controlled protection device, miniature circuit breaker, molded case circuit breaker, residual current operated circuit breaker with overcurrent protection, residual current device, residual current circuit breaker, or surge protection device.

[0029] The invention will now be explained using several exemplary embodiments and the accompanying drawing. Each drawing is schematic and not to scale. Fig. 1 is an oblique view of an under-plug protection part; Fig. 2 is an oblique view of the in Fig. 1 Fig. 3 shows a protective insert that is pushed onto a clamping frame of a screw terminal; Fig. 3 shows two different views of an alternative variant of the protective insert; Fig. 4 shows two different views of another alternative variant of the protective insert; Fig. 5 shows a screw terminal with the insert shown in Fig. 3. Fig. 3 shown under-plug protection part; Fig. 6 a side view of the in Fig. 5 The screw terminal shown is inserted into a housing half-shell of an installation device; Fig. 7 is a sectional view of the [part]. Fig. 5 screw terminal shown, inserted into an installation device; Fig. 8 an oblique view of the in Fig. 5 The screw terminal shown is in the open position, inserted into an installation device; Fig. 9 is an oblique view of the screw terminal shown in the open position. Fig. 5 The screw terminal shown is in the closed position and is inserted into an installation device; Fig. 10 shows a side view of the [part]. Fig. 5 The screw terminal shown is inserted into a housing half-shell of an installation device with a slider hand-operated mechanism; Fig. 11 is an oblique view of the Fig. 5 The screw terminal shown is in the open position, inserted into an installation device with a slide hand actuator; Fig. 12 is an oblique view of the screw terminal shown in Fig. 12, which is in the open position. Fig. 5 The screw terminal shown in the closed state, inserted into an installation device with a slider hand operation; and Fig. 13 a side view of an under-plug protection part.

[0030] Fig. 1 Figure 1 shows a protective insert 1, which is suitable for sliding onto a clamping frame of a screw terminal. For the sake of simplicity, the description is shown in Fig. 1 A right-handed Cartesian coordinate system is given. For the sake of simplicity, the terms "top" and "bottom" are used in relation to the underpinning protective part 1, as the underpinning protective part 1 is in Fig. 1 oriented; however, these directional and location specifications should not be restrictive for the position of the under-plug protection part 1 in an actual application.

[0031] The under-plug protection element 1 has the form of a closed frame lying in the xy-plane, comprising two longitudinal elements L1, L2 opposite each other in the y-direction at a clear distance 1, and a first and a second transverse element Q1, Q2 in the x-direction. Depending on the orientation of the under-plug protection element 1, the first transverse element Q1 can also be referred to as the upper transverse element and the second transverse element Q2 as the lower transverse element. The two transverse elements Q1, Q2 are positioned opposite each other at a clear distance q and connect the longitudinal elements L1, L2 to each other at their respective ends.

[0032] The two longitudinal elements L1, L2 have a rectangular cross-section; they have two wider side surfaces whose surface normals are parallel to the x-axis, and two narrower side surfaces whose surface normals are parallel to the z-axis.

[0033] The first transverse element Q1 forms a ring 10 that encloses a circular through-hole A for the insertion of a screw shaft. The second transverse element Q2 has a rectangular cross-section, similar to the longitudinal elements L1 and L2. A web 14 is formed on a narrow side face of the second transverse element Q2, which carries a cover apron S in the form of a square plate that serves as undercut protection. The plane of the web 14 lies parallel to the xz-plane, while the plane of the cover apron S lies parallel to the xy-plane. The cover apron S projects beyond the second transverse element Q2 in a direction away from the first transverse element Q1.

[0034] A nose 15 is formed centrally on a downward-pointing edge of the cover apron S, i.e., on the edge pointing against the y-direction, which projects from the edge against the y-direction and whose function is Fig. 6 The nose, viewed in the z-direction, can have a rectangular, preferably square, outline.

[0035] At each of the two frame corners of the under-protection part 1, formed by the transitions from the longitudinal elements L1, L2 to the second transverse element Q2, a spring element F in the form of a foot is molded. The two spring elements F each have the shape of a 90° arc, with the two arcs pointing towards each other. While the plane of the cover apron S is offset in the z-direction relative to the frame plane of the under-protection part 1, the spring elements F are offset in the opposite direction to the frame plane of the under-protection part 1. If the under-protection part 1 is moved against a fixed surface in the opposite direction to the y-direction, the spring elements F are bent, resulting in a spring force in the y-direction.

[0036] Fig. 2 This shows in Fig. 1 The illustrated under-plug protection part 1 is slid onto a clamping frame 2 of a screw terminal. For the sake of simplicity, in Fig. 2 A right-handed Cartesian coordinate system is specified. The clear distances l, q of the longitudinal and transverse elements L1, L2 and Q1, Q2 respectively are dimensioned such that the under-mounting protective part 1 has only enough play against the clamping frame 2 to allow manual sliding of the under-mounting protective part 1 onto the clamping frame 2, but on the other hand, to prevent unwanted and disruptive movement of the under-mounting protective part 1, once slid onto the clamping frame 2, relative to the clamping frame 2.

[0037] The clamping frame 2 has the form of a closed frame lying in the xy-plane, comprising two opposing side parts 21, 22 in the y-direction and a head web 23 and a bottom web 24, each in the x-direction. The head web 23 and the bottom web 24 connect the side parts 21, 22 to each other at their ends.

[0038] The frame elements forming the clamping frame, i.e., the two side parts 21, 22, the head web 23, and the base web 24, each have a rectangular cross-section. These frame elements each have two wider side faces whose surface normals are parallel to the xy-plane and two narrower side faces whose surface normals are parallel to the z-axis. A circular threaded bore 26 for receiving a screw, whose axis runs in the y-direction, is located in the center of the head web 23. Furthermore, the head web 23 has a threaded flange 25 on its outer surface facing away from the base web 24, which surrounds the threaded bore 26.The surface of the bottom web 24 facing the head web 23 is designed as a profiled surface 27 in the form of ribs; into the profile 27 of the bottom web 24, which is preferably made of a relatively hard metal such as iron or steel, an end of a conductor, which usually has a conductor (solid wire or strands) made of a relatively soft metal such as copper or aluminum, can be pressed by the contact pressure of a screw screwable in the threaded bore 26, so that the conductor can be clamped there particularly securely (force fit + form fit).

[0039] The under-mounting protective element 1 encloses the clamping frame 2 on its entire outer circumference, with the feed-through opening A of the under-mounting protective element 1 being aligned with the threaded bore 26 of the clamping frame 2 and the cover skirt S of the under-mounting protective element 1 projecting beyond the bottom web 24 in a direction away from the top web 23. The first transverse element Q1 of the under-mounting protective element 1 has an internal corner on its side facing the second transverse element Q2 along the feed-through opening A, against which the threaded flange 25 of the clamping frame 2 abuts.

[0040] Fig. 3 shows two different views of an alternative variant of the under-plug protection part 1. All elements of the in Fig. 3 The depicted under-plug protection part 1, except for the first transverse element Q1, is designed identically to the one shown in the Fig. 1 and 2 depicted under-plug protection part 1. Unlike in Fig. 1 and 2 forms in the Fig. 3 The first transverse element Q1 of the shown under-protection part 1 has a semicircular arc 11 that encloses the feed-through opening A on three sides. The opening of the semicircular arc 11 is located on the side of the under-protection part 1 opposite the cover apron S.

[0041] Fig. 4 shows two different views of another alternative variant of the under-plug protection part 1. All elements of the in Fig. 4 The depicted under-plug protection part 1, except for the first transverse element Q1, are designed identically to those shown in the Fig. 1 bis 3 illustrated under-plug protection parts 1. As in Fig. 3 points in the Fig. 4 In the shown undercut protection part 1, the first transverse element Q1 forms a semicircular arc 11 that encloses the feed-through opening A on three sides. However, the semicircular arc 11 has a separation joint 12 in the region of one of its apex points. This allows the arc halves 11a, 11b of the arc 11, separated by the separation joint 12, to be bent open so that they can be guided over a pressure piece mounted on a screw, see Fig. 5 . This flexibility is achieved by manufacturing the underlay protection part 1 from a plastic, e.g. PA66 without glass fiber reinforcement.

[0042] In Fig. 3 and 4 The spring elements F and the inner corner 13, which are identical in all three drawn variants of the under-plug protection part 1, can be seen.

[0043] Fig. 5 Figure 1 shows a screw terminal 3 of the elevator type, comprising a clamping frame 2, a protective insert 1 slid onto the clamping frame 2, a screw 30 screwably mounted in the clamping frame, a pressure piece 40 mounted on a screw head of the screw 30, and a hand guard 42 attached to the pressure piece 40. The hand guard prevents the installer's hand from coming into contact with conductive components when gripping the installation device, e.g., during mounting on a DIN rail or when moving it. The screw terminal 3 is suitable for use in an installation device; in this case, Fig. 5 A terminal connection K of the installation device is also shown, which protrudes into the interior of the terminal frame 2. For the sake of simplicity, the terms "top" and "bottom" are used in relation to the screw terminal 3, as screw terminal 3 is in Fig. 5 oriented; however, these directional and location specifications should not restrict the position of the screw clamp in an actual application.

[0044] The screw 30 has a screw head with a Phillips recess for the insertion of a suitable screwdriver and a threaded body adjoining the screw head, the screw being inserted from above into a threaded bore of the clamping frame 2, as shown in Fig. 2 As shown, it is screwed in. By further turning the screw 3, the pressure piece 40 is moved from above and the bottom web 24 from below against the terminal connection K.

[0045] A head plate of the pressure piece 40 surrounds the screw head of the screw 30, so that an axial movement of the screw generates a corresponding movement of the pressure piece.

[0046] The pressure piece 40 can be made of tin-plated steel, the clamping frame 2 of copper-plated steel, the gripping guard 42 of plastic, the under-insertion guard 1 of plastic, and the screw 30 of steel. These material specifications are only examples and are not exhaustive. The parts can also be made of other suitable materials.

[0047] Fig. 6 is a side view of the in Fig. 5 The screw terminal 3 shown is inserted into a second housing half-shell 62 of a housing 60 of an installation device 4. Fig. 6 The screw shaft 32 of the screw 30, which is provided with a screw thread, is visible, as is the pressure piece 40, which has a ring element placed around the screw head 31 of the screw 30, such that an axial movement of the screw head 31 leads to a movement of the pressure piece 40 relative to the stationary terminal connection K in the interior of the clamping frame 2. The downwardly projecting nose 15 molded onto the cover apron S always remains behind the chamfered frame 68 in every position of the cover apron S, see Fig. 12 , and thus provides guidance for the cover apron S.

[0048] Fig. 7 is a sectional view of the in Fig. 5 The screw terminal 3 shown is inserted into the housing 60 of the installation device 4, which consists of a first housing half-shell 61 and a second housing half-shell 62. Fig. 6 and 7Figure 3 shows a state of the screw terminal 3 in which an upper conductor entry opening 66, located between the pressure piece 40 and the terminal connection K, is open, and a lower conductor entry opening 67, located between the terminal connection K and the base web 24 of the clamping frame 2, is closed. A cavity located below the base web 24 of the clamping frame 2 is covered by the cover apron S in such a way that a conductor end cannot be inserted underneath.

[0049] The downward-pointing lug 15, which is formed centrally on the downward-pointing edge of the cover apron S, prevents the cover apron S from slipping out of the lower ladder entry opening 67 under any part tolerance conditions. Alternatively, to achieve this effect, the entire lower edge of the cover apron S could be extended to the lower edge of the lug 15, which would require more material than if only the centrally located lug 15 were formed. However, a material-intensive extension of the entire cover apron S is unnecessary, since the cover apron S does not need to hermetically seal the lower ladder entry opening 67, but merely prevent a ladder, which always has a certain minimum thickness, from being inserted into the lower ladder entry opening 67. Therefore, the downward projection of the lug 15 beyond the lower edge of the cover apron S is chosen to be approximately the same size as the minimum diameter of a ladder end.By designing the guide element and anti-threading device as a nose 15, material is saved.

[0050] Fig. 8 and 9 are oblique views of the in Fig. 5 screw terminal 3 shown, inserted into a housing 60 of an installation device 4; showing Fig. 8 the screw terminal 3 in the open state and Fig. 9 The screw terminal 3 in the closed state. Both figures show an access opening 65 arranged in the housing 60, through which the screw head of the screw 30 of the screw terminal 3 is accessible, so that it can be acted upon, for example, with a screwdriver. On a narrow side 64 of the housing 60, which is composed of two housing half-shells 61, 62 and is recognizable by a joining line 63, the conductor entry openings 66, 67 of the screw terminal 3 are accessible through corresponding recesses in the housing 60. While in the Fig. 8 In the shown open state of screw terminal 3, the upper conductor entry opening 66 is fully open and the lower conductor entry opening 67 is open by approximately 1.5 mm. Fig. 9 In the closed state of screw terminal 3 shown, both conductor entry openings 66, 67 are completely closed. In both states, however, the cover apron S prevents the screw terminal 3 from being inserted underneath.

[0051] Fig. 10 is a side view of the in Fig. 5 The screw terminal 3 shown is inserted into a first housing half-shell 61 of a housing 60 of an installation device 4, which has a sliding hand actuation 50; the sliding hand actuation 50 enables the installation device 4 to be released from a DIN rail or from a busbar assembly without tools.

[0052] Fig. 11 and 12 are oblique views of the in Fig. 5 screw terminal 3 shown, inserted into a housing 60 of an installation device 4, which has a slide hand actuation 50. Fig. 11 The screw terminal 3 is shown in the open state and Fig. 12 The screw terminal 3 in the closed state. Both figures show an access opening 65 arranged in the housing 60, through which the screw head of the screw 30 of the screw terminal 3 is accessible, so that it can be acted upon, for example, with a screwdriver. On a narrow side 64 of the housing 60, which is composed of two housing half-shells 61, 62 and is recognizable by a joining line 63, the conductor entry openings 66, 67 of the screw terminal 3 are accessible through corresponding recesses in the housing 60. While in the Fig. 11 In the shown open state of screw terminal 3, the upper conductor entry opening 66 is fully open and the lower conductor entry opening 67 is open with an opening height of approximately 1.5 mm. Fig. 12 In the closed state of screw terminal 3 shown, both conductor entry openings 66, 67 are completely closed. In both states, however, the cover apron S prevents the screw terminal 3 from being inserted underneath.

[0053] When the lower conductor entry opening 67 is completely closed, as shown in Fig. 11 As shown, the distance between the lower edge S1 of the cover skirt S and the upper edge 68K of the cover 68 formed on the housing 60 is smaller than the smallest possible diameter of a conductor end. The downward-pointing lug 15, which is formed centrally on the downward-pointing edge S1 of the cover skirt S, prevents the cover skirt S from slipping out of the lower conductor entry opening 67 under any part tolerance conditions; in other words, the lug prevents the cover skirt S from coming in front of the cover 68. Alternatively, to achieve this effect, the entire lower edge of the cover skirt S could be extended to the lower edge of the lug 15, which would require more material than if only the centrally located lug 15 is formed.However, a material-intensive extension of the entire cover apron S is unnecessary, as the cover apron S does not need to hermetically seal the lower ladder entry opening 67, but merely needs to prevent a ladder, which always has a certain minimum thickness, from being inserted underneath. Therefore, the downward projection of the nose 15 beyond the lower edge of the cover apron S is chosen to be approximately the same size as the minimum diameter of a ladder end. By forming the guide element and anti-disengagement device as a nose 15, material is thus saved.

[0054] Fig. 13 Figure 1 shows a side view of a protective insert 1 that is slid onto a clamping frame 2 of a screw terminal. For the sake of simplicity, the following is shown in the figure 1: Fig. 13 A right-handed Cartesian coordinate system is specified. The underlay protection part 1 has the form of a closed frame with two longitudinal elements and two transverse elements connecting the longitudinal elements to each other, of which in Fig. 13 A first longitudinal element L1 and the two transverse elements Q1 and Q2 are visible. The first transverse element Q1 has a through-hole A for inserting a screw shaft. A web 14 extending in the z-direction is integrally formed on the second transverse element Q2. This web supports a plate-shaped cover apron S, which serves as under-plug protection and extends in the xy-plane. The clamping frame 2 has the form of a closed frame with four frame elements, of which in Fig. 13 a first side panel 22, a headboard 23 and a bottom panel 24 are visible.

[0055] The cover apron S is positioned on the under-protection part 1 such that its lower edge S1, i.e., the side edge of the cover apron S facing away from the first transverse element Q1, projects below the lower edge 24UK of the bottom web 24, i.e., the side of the bottom web 24 facing away from the head web 23, by a projection length b in a direction away from the head web 23, i.e., opposite to the y-direction. The projection length b is chosen such that the cover apron S prevents the clamping chamber of a screw clamp from being inserted below it in all possible positions of the clamping frame 2.

[0056] The in Fig. 13 The depicted under-plug protection part 1 differs from the one in Fig. 1 The depicted under-plug protection part 1 differs essentially in the following points: a) the web 14 of the in Fig. 13 The depicted undercut protection part 1 is attached to the underside of the second transverse element Q2, whereas the web 14 of the in Fig. 1 a) the depicted under-plug protection part 1 is attached to the front of the second transverse element Q2; b) which is in Fig. 13 The depicted under-plug protection part 1 has no spring elements F; and c) the one in Fig. 13 The depicted under-protection part 1 does not have a nose 15 on the lower edge S1 of the cover apron S.

[0057] The under-mounting protective element 1 is designed such that its longitudinal elements L1, L2 are located approximately in the middle of the side parts 21, 22 of the clamping frame 2 onto which the under-mounting protective element 1 is mounted; that is, the longitudinal elements L1, L2 divide, in a view of the clamping frame 2 opposite to the x-direction, the side parts 21, 22 of the clamping frame 2 into approximately equal contact surfaces, namely a front contact surface C1 and a rear contact surface C2. In these contact surfaces C1, C2, the clamping frame 2 supports the screw tightening torque, which can be in a relatively high value range, e.g., 3.5 Nm, within the housing 60. In the case of an off-center positioning of the under-mounting protective element 1 on the clamping frame 2, the screw tightening torque could be supported via the under-mounting protective element 1, which would be very disadvantageous and could lead to problems.Due to the central positioning of the under-protection part 1 on the clamping frame 2, the bridge 14 is necessary to attach the cover apron S to the second transverse element Q2 of the under-protection part 1.

Claims

1. Screw terminal (3) in the form of a lift terminal, having - a clamping frame (2) with a top web (23) and a base web (24) that are situated opposite one another, - a screw (30) which is mounted screwably in a threaded bore (26) of the top web (23), and - an under-plugging protection part (1) which is pushed onto the clamping frame (2), wherein the under-plugging protection part is produced from a plastic, - wherein the under-plugging protection part (1) has the form of a frame with two longitudinal elements (L1, L2), which are situated opposite one another, and with a first and a second transverse element (Q1, Q2), which are situated opposite one another and in each case connect the longitudinal elements to one another, - wherein the first transverse element (Q1) has a through-passage opening (A) for through-passage of a screw shank of the screw (30), - wherein the first transverse element (Q1) forms a semicircular arc (11) which surrounds the through-passage opening (A) on three sides, and - wherein a covering skirt (S) serving as under-plugging protection is integrally formed on the second transverse element (Q2), wherein - the under-plugging protection part (1) surrounds the clamping frame (2), - the through-passage opening (A) of the under-plugging protection part (1) is arranged in alignment with the threaded bore (26), and - the covering skirt (S) of the under-plugging protection part (1) protrudes below (b) the base web (24) in a direction away from the top web (23), characterized in that the semicircular arc (11) has a parting joint (12) in the region of an arc peak of the arc (11).

2. Screw terminal (3) according to Claim 1, wherein the top web (23), on its outer side, facing away from the base web (24), bears a threaded flange which surrounds the threaded bore (26), wherein the first transverse element (Q1) of the under-plugging protection part (1), on its side facing towards the second transverse element (Q2), has along the through-passage opening (A) an inner corner against which the threaded flange abuts.

3. Screw terminal according to either of Claims 1 and 2, wherein the screw terminal (3) is a double-chamber terminal.

4. Screw terminal according to one of Claims 1 to 3, wherein the under-plugging protection part (1) is seated on the clamping frame (2) in such a way that the two longitudinal elements (L1, L2) of the under-plugging protection part (1) subdivide side parts (21, 22) of the clamping frame (2), each of which extends between the top web (23) and the base web (24), in each case into abutment surfaces (C1, C2) of approximately equal size.

5. Screw terminal according to one of the preceding claims, wherein the covering skirt (S) is in the form a plate which is parallel to the plane defined by the longitudinal and transverse elements (L1, L2; Q1, Q2).

6. Screw terminal according to one of the preceding claims, wherein at least one spring element (F) is integrally formed on the second transverse element (Q2) and is configured in such a way that an elastic deformation of the spring element (F) that takes place during a movement of the under-plugging protection part (1) in the direction from the first transverse element (Q1) to the second transverse element (Q2) in a direction parallel to the longitudinal elements (L1, L2) results in a restoring force in an opposite direction.

7. Screw terminal according to one of the preceding claims, wherein the under-plugging protection part (1) is produced by plastic injection moulding.

8. Installation unit (60, 61, 62) having a screw terminal (3) according to one of Claims 1 to 7.

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