Second scissor element for a scissor mechanism for a seal

Description

[0001] The invention relates to a second scissor element for a scissor mechanism for a seal with a lowerable sealing strip, wherein the scissor mechanism has a first scissor element and the second scissor element which are pivotally mounted on one another.

[0002] Seals with two scissor mechanisms are known from documents CH 465 830 and DE 60 2004 009 845 T2. Document WO 2009 / 155295 discloses a scissor mechanism with two scissor elements.

[0003] The two seals described in documents CH 465 830 and DE 60 2004 009 845 T2 have continuous release rods from their actuators to a reset mechanism. These release rods are coupled to the scissor mechanisms via the overload mechanisms, which translate the horizontal movement of the actuator of a seal mounted in a door into a vertical movement of the sealing strip.

[0004] The seal from document CH 465 830 has springs, designated in the cited document with the reference numeral 16, each of which is assigned to a scissor mechanism of the disclosed seal. The document describes the function of the springs as follows: the springs 16 delay the movement of a seal trigger to the scissor mechanisms and the sealing strip. At the same time, these springs, which is not mentioned in the document, protect the seal from overload, which can occur if the sealing strip's travel, predetermined by the adjustment and installation of the seal in or on a door, is blocked for whatever reason when the seal is triggered, and the sealing strip cannot travel the predetermined travel.In such a case, the springs 16 are tensioned when the springs are triggered and remain tensioned because they cannot transmit the force introduced into the trigger to the blocked sealing strip and the scissor mechanisms blocked as a result.

[0005] In the seal described in document CH 465 830, a return mechanism and the scissor mechanisms are supported on a seal housing. This means that the return mechanism and the scissor mechanisms have structures that are either rigidly (return mechanism) or pivotably connected (scissor mechanisms) to the housing.

[0006] In document DE 60 2004 009 845 T2, overload mechanisms for protecting the seal in the event of a sealing strip blockage are explicitly described in paragraph

[0040] of the seal. The overload mechanism results in one end of the first longer scissor element being slidably guided on the seal's trigger rod.

[0007] In the seal described in document DE 60 200 009 845 T2, a return mechanism, as well as the scissor mechanisms, are supported on an inner housing. The inner housing is referred to in the document as the motion module section. This inner housing is firmly connected to an outer housing and extends the entire length of the seal. The outer housing is referred to in the document as the housing section.

[0008] Both seals have some disadvantages.

[0009] A disadvantage of the seal from document CH 465 830 is that the lowering mechanism, in particular, is made from a large number of individual parts and is therefore complex to manufacture. Although the lowering mechanism of the seal from document DE 60 2004 009 845 T2 has fewer individual parts, it is also not easy to manufacture. This is particularly true for the overtravel mechanism, which also has the disadvantage that the end of the long scissor element, which is slidably guided on the trigger rod, can fall out of the guide, thereby impairing the functionality of the seal.

[0010] The invention was therefore based on the object of improving a seal of the type mentioned at the outset so that it is easier to manufacture and functions more reliably.

[0011] The object underlying the invention is achieved according to the invention in that the second scissor element is essentially H-shaped and designed in one piece.

[0012] This H-shaped second scissor element has the advantage of being a single-piece design—like the optional first scissor element—and is easy to install. It also offers the option of being stored in a space-saving manner when the seal is not deployed.

[0013] A second scissor element according to the invention can have a connecting web from which two arms and two legs extend. Each arm and leg can be oriented in opposite directions. The arms can be shorter, the same length as the legs, or longer than the legs.

[0014] A second scissor element according to the invention may have two pins projecting outward in opposite directions at the ends of the arms. The pins may have a circular cross-section.

[0015] It is possible for the second scissor element to have two pins at the ends of the legs that extend inward in opposite directions. The pins can have a circular cross-section.

[0016] A scissor mechanism with the second scissor element according to the invention can have a first scissor element. The scissor elements are then pivotally mounted on one another, with the first scissor element having a first section and a second section, with a bearing for the second scissor element provided between the sections. The first section of the first scissor element forms a frame with an opening that can be used for securely guiding the first section.

[0017] To mount the second scissor element on the first scissor element, the inwardly projecting pins of the second scissor element can be inserted into the blind holes or the through hole of the first scissor element. It is possible and advantageous if the ends of the legs of the second scissor element then rest against the bearing shells of the first scissor element.

[0018] The legs of the second scissor element can have a spacing that corresponds to the width of the second section of the first scissor element. This allows the second section of the first scissor element to penetrate between the legs of the second scissor element when the seal is not triggered.

[0019] One free end of the first section of the first scissor element is circularly cylindrical. The free end thus has a circular cross-section. This makes the free end of the first section suitable as a bearing pin around which the first scissor element can rotate when the seal is triggered and the sealing strip is lowered.

[0020] The bearing for the second scissor element can have two blind holes with a circular cross-section that are aligned in opposite directions, or a through hole. A bearing shell can be connected to each of the blind holes or through hole openings, the radius of curvature of which corresponds to the radius of the cross-section of the blind holes. These bearing shells can serve to improve the mounting of the second scissor element on the first scissor element and, in particular, enable greater force transmission from the first to the second scissor element.

[0021] The second section of a first scissor element can be a rod or have a rod-like configuration. The second section can be narrower than the first section. This can be particularly useful for space-saving accommodation of the first scissor element when the seal is not triggered.

[0022] Two pins oriented in opposite directions can be provided at a free end of the second section of a first scissor element. These pins could be used to pivotally mount the free end of the second section of the first scissor element on the sealing strip. The pins preferably have a circular cross-section.

[0023] The second section may have a tapered area extending from the blind holes or the through hole to the free end of the second section. This tapered area is advantageous for the assembly of the second scissor element, which will be explained below.

[0024] Further features and advantages of a seal are described with reference to the attached illustrations. They show: Fig. 1 and 1a a perspective view of the seal in a non-triggered state and in a triggered state, Fig. 2 and 2a a front view of the seal in a non-triggered state and in a triggered state, Fig. 3 and 3a a lock-side view of the seal in a non-triggered state and in a triggered state, Fig. 4 and 4a a hinge-side view of the seal in a non-triggered state and in a triggered state, Fig. 5 and 5a a section through the seal in a non-triggered state according to the line VV in Fig. 2 and in a triggered state according to the line Va-Va in Fig. 2a , Fig. 6 and 6a a section through the seal in a non-triggered state according to the line VI-VI in Fig. 2 and in a triggered state according to the line Vla-Vla in Fig. 2 , Fig. 7 and 7a a front view of the seal without housing and without sealing strip in a non-triggered state and in a triggered state, Fig. 8 and 8a a front view of the seal without housing, without holding module and without sealing strip in a non-triggered state and in a triggered state, Fig. 9 and 9a an enlarged section IX from Fig. 8 or an enlarged section IXa from Fig. 8a , Fig. 10 and 10a an enlarged section X from Fig. 8 . or an enlarged section Xa from Fig. 8a , Fig. 11 a perspective view of the scissor mechanism, Fig. 12 a perspective view of a short scissor leg, Fig. 13 a perspective view of a long scissor leg, Fig. 14a and b views of the assembly of the scissor mechanism, Fig. 15a to d front views of a unit consisting of connecting rods and sliding element, Fig. 16a to d views of the aforementioned unit from below, Fig. 17 a front view of an overload spring holder, Fig. 18 a view of the overload spring holder from below, Fig. 19a and b views of the assembly of the overload mechanism, Fig. 20a and b sectional views of the assembled overload mechanism Fig. 21 a variant of the seal,

[0025] A seal has a housing that has a consistent cross-sectional profile along its length. In the example shown, the housing is essentially in the shape of an inverted U with two legs 12 and a connecting web 11 that connects the two legs 12. Two mirror-image webs 111 are attached to an inner side of the web 11 of the housing 1. These webs are slightly undercut on mutually facing sides 1111, so that the facing sides 1111 form a groove. The mutually facing sides 1112 of the webs 111 are slightly slanted.

[0026] The housing can be mounted in a groove of a door leaf in a known manner. This can be achieved, for example, using mounting brackets, which will be discussed later. Those skilled in the art will be familiar with various types of mounting from the prior art, particularly from published patent applications. Depending on the type of mounting, the housing can be modified, for example, to provide channels, webs, screw holes, or other features useful for attaching the seal to a door.

[0027] A seal also has a sealing strip. In the example, the sealing strip is made of two parts. However, it could be one piece or have more than two parts. In principle, any sealing strip known from the prior art can be used. In the example, the sealing strip comprises a rigid holding profile 13, preferably made of aluminum, and an elastomeric sealing profile 14. In the example, both have a constant cross-sectional profile along their length. In the example, the holding profile 13, like the sealing profile, is essentially U-shaped in cross-section. The holding profile 13 and the sealing profile 14 each have a connecting web 131, 141 and two legs 132, 142 each, which are connected to one another via the connecting web 131, 142.

[0028] The sealing profile 14 is fastened via locking webs 143 in locking channels 133 of the holding profile 13.

[0029] On the inside of the legs 132 of the holding profile 13, two webs 134 are provided, which together with the connecting web 131 form channels, the purpose of which will be explained in more detail below.

[0030] Two modules Ma, Mb are arranged in the seal, which in the exemplary embodiment include all parts that serve to ensure safe movement of the sealing strip relative to the housing.

[0031] Some of the seal parts belonging to modules Ma and Mb are identical in both modules. These parts can then be used in modules Ma and Mb for the same functions as modules Ma and Mb. Some modules Ma and Mb also have special functions that require special parts. Functions performed by the first module in the example may be performed by the second module in a different seal design, and vice versa. It is possible to modify the parts of modules Ma and Mb so that they can perform fewer, different, or additional functions if necessary.

[0032] Identical or functionally similar parts of modules Ma, Mb have the same reference numbers and are distinguished by the suffixed letters a and b, where a stands for parts of the first module and b for parts of the second module. When discussing details of parts of modules Ma, Mb, these will be referred to without suffixed letters if they are found in parts of both modules Ma, Mb.

[0033] In the example, both modules Ma, Mb of the seal have the function of connecting the sealing strip and the housing and, when the seal is triggered by pressing a trigger 12, converting the movement of the trigger 12 into a movement of the sealing strip relative to the housing. For this purpose, each module Ma, Mb has a scissor mechanism Sa, Sb. To protect this scissor mechanism Sa, Sb of each module Ma, Mb in the event of an overload, each module Ma, Mb also has an overload mechanism Ua, Ub.

[0034] The modules Ma, Mb can be placed in a housing 1 at the discretion of a specialist. However, it is also possible for a seal to have no housing and the modules to be placed directly in a door groove. It is possible to design a seal to have only one module.

[0035] The first module Ma comprises a module housing 2a. This has a substantially constant cross-sectional profile in the shape of an inverted U. It has a connecting web 21 that connects two legs 22 of the module housing 2a. Webs 221 are attached to the inner sides of the legs 22. Together with the connecting web 21, these form channels, the function of which will be explained below.

[0036] The connecting web 21 projects beyond the outer sides of the legs 22. These projecting ends 211 of the connecting web are designed such that they form a fit with the grooves on the mutually facing sides 1111 of the webs 111 of the housing 1. In particular, the fit can form a clearance fit with a slight clearance. The module housing 2a is inserted with the ends 211 into the grooves on the mutually facing sides 1111 of the webs 111 of the housing 1 and is thus fixed in the housing at least in a form-fitting manner. Complete fixing can be achieved, for example, by at least selectively deforming the webs 111 of the housing inwards, i.e. against the ends 211 or the legs 22. Parts of the webs 111 can thereby be pressed against the ends 211 or legs 22, so that at least a force-locking connection is established.

[0037] Trigger-side ends of the module housing 2a end flush with a trigger-side end of the housing 1. In contrast, the connecting web 21 is missing in an area at the trigger-side end of the module housing. The reason for the absence of the connecting web at the trigger-side end of the module housing 2a is that the absence of the connecting web 21 at the trigger-side end of the module housing 2a creates space to insert a fastening angle into the housing 1.

[0038] In an area of ​​the module housing 2a of the first module Ma, remote from the trigger, two opposing holes are provided in the legs 22, directly adjacent to the webs 221. Corresponding holes are also provided in the module housing 2b of the second module Mb. Pins 71 of a short scissor element 7a are rotatably arranged in these holes. These pins 71 also bear against the underside of the webs 221, thereby supporting the pins 71 in the event of a load toward the webs 221 and protecting them from shearing off.

[0039] The short scissor element 7a of the first module Ma – it is structurally identical to the short scissor element 7b of the second module Mb – is essentially H-shaped. It has a connecting web 72, from which two arms 73 and two legs 74 extend. At the ends of the arms 73, which are slightly shorter than the legs 74, are the outwardly projecting pins 71, whose function has already been explained. The ends of the arms 73 rest against the webs 221, which supports the arms 73 when subjected to a load in the direction of the webs 221. A load on the short scissor element 7a – and thus on the pins 71 and the arms 73 – can arise when the sealing strip is pressed against a floor during lowering or when the sealing strip is lowered.

[0040] On the legs 74, two inwardly projecting pins 75 are provided, which serve to connect to a long scissor element 6a.

[0041] The long scissor element 6a of the first module Ma—it is structurally identical to a long scissor element 6b of the second module Mb—can be divided into two sections, namely a first section 61, which forms a frame, and a second section 62, which forms a rod. The two sections 61, 62 are connected to one another. In the area of ​​the connection, the second section 62 of the long scissor element 6a has two outwardly opening blind holes. The inwardly projecting pins 75 of the short scissor element 7a are inserted into these blind holes. This pivotally connects the long and short scissor elements 6a, 7a.

[0042] The pins 75 inserted into the blind holes or the ends of the legs 74 rest on bearing shells 611 formed on the first section 61 in the region of the connection of the first section 61 to the second section 62. This makes it possible to transmit greater forces into the long scissor element 6a via the pins 75 or legs 74 than if the bearing shells were missing.

[0043] The second section 62 of the long scissor element 6a has a conically tapered area extending from the blind holes toward the free end of the second section 62. This conical taper of the second section 62 facilitates the assembly of the short scissor element 7a to the long scissor element 6a. For this purpose, the inwardly projecting pins 75 of the short scissor element can be placed on the second section 62 at the most tapered end of the taper, so that the pins are located on either side of the second section. From this end of the taper, the pins 75 can then be pushed toward the blind holes. In the process, the pins 75 are bent apart until they finally engage in the blind holes.

[0044] The free end of the first section 61, or the opening present in this first section 61, serves to guide and support the long scissor element 6a, which will be explained in more detail below. This free end is movable relative to the module housing 2a.

[0045] At the free end of the second section 62 of the long scissor element, two outwardly projecting pins 63 are provided, which serve to connect the long scissor element 6a to the retaining profile 13. The pins 63 are movably guided and mounted in the channels formed by the webs 134 and the connecting web 131 of the retaining profile 13.

[0046] The second section 62 of the long scissor element 6a has a width that is not greater than the distance between the legs 74 of the short scissor element 7a. Thus, it is possible for the second section 62 to be immersed between the legs 74, for example, when the seal is not triggered.

[0047] The long scissor element 6a and the short scissor element 7a together form a first scissor mechanism Sa of the first module Ma, which is also present in the second module as a second scissor mechanism Sb formed by the long scissor element 6b and the short scissor element 7b.

[0048] The first module Ma has a sliding part 3a. This sliding part has a flat, rod-like section 31 that extends over the entire length of the sliding part 3a. This flat, rod-like section 31 has approximately the shape of a T. Two projecting edges 311 of the rod-like section 31 protrude into the channels formed by the webs 221 and the connecting web 21 of the module housing 2a. The edges 311, and thus the entire sliding part 3a, are slidably guided in the channels.

[0049] On a bottom side of the rod-like section 31, three different structures 32, 33a, 34a are provided.

[0050] The structure 32 at a trigger-side end of the sliding part 3a serves as a first connecting structure, which is provided for connecting the sliding part 3a of the first module Ma to a first connecting rod 8. Furthermore, the structure 32 is part of the overload mechanism of the first module Ma.

[0051] The structure 33 interacts with the scissor mechanism Sa of the first module and is part of the overload mechanism of the first module Ma.

[0052] The structure 34 is a second connecting structure which serves to connect the sliding part 3a of the first module Ma to a second connecting rod 9.

[0053] The first and the second connecting structures 32, 34 are designed such that both tensile forces and compressive forces can be transmitted via the connecting structures 32, 34.

[0054] The structure 33 has an arm 331 extending toward the trigger-side end, which extends parallel to the rod-like portion 31 of the sliding part 3a. This arm 331 passes through the opening in the first portion 61 of the long scissor element 6a of the scissor mechanism Sa of the first module Ma. A free end 612 of the first portion 61 is thus supported and guided between the arm 331 and the rod-like portion 31 of the sliding part 3a.

[0055] The free end 612 is held by a holder 4a for an overload spring 5a and the overload spring 5a of the first module Ma in a position between the arm 331 and the rod-like portion 31 of the sliding part 3a. The overload spring 5a is a helical compression spring. The holder 4a for the overload spring is rod-like.

[0056] The holder can be roughly divided into four areas: 41, 42, 43, 44.

[0057] A first region 41 is designed to be guided between the arm 331 and the rod-like section 31 of the sliding part 3a. For this purpose, the first region 41 of the holder 4a has a channel on its underside, into which a web 3311 engages, which is provided on the upper side of the arm 331. A free end 411 of the first region 41 has a groove and forms a bearing shell for the free end 612 of the first section 61 of the long scissor element 6a.

[0058] This first region is adjoined by a second region 42, which has a larger cross-sectional area than the first region 41. This second region 42 forms, on the one hand, a stop, and on the other hand, a first end of the overload spring 5a, which is plugged onto the third rod-like region 43 of the holder 4a, rests on this second region. A second end of the overload spring 5a rests on the structure 32 of the sliding part 3a. The overload spring 5a presses the holder, and in particular the first region 41 of the holder, against the structure 33 of the sliding part. As a result, the free end 612 of the first section of the long scissor element 6a is held between the arm 331 and the rod-like section 31.The stop function of the second region 42 of the holder 4a ensures that the overload spring 5a does not press the free end 612 of the first section 61 of the long scissor element 6a against the structure 33, which could impair the easy pivoting of the long scissor element. The length of the first region 41 of the holder 4a is selected such that the free end 612 of the first section 61 of the long scissor element 6a is mounted with at least a slight amount of play between the structure 33 and the first region 41 of the holder 4a.

[0059] The third region 43 of the holder 4a is adjoined by a fourth region 44. This fourth region 44 is guided in a blind hole in the structure 32. A lower boundary wall 321 of the blind hole has a slot that is open downwards. This slot tapers from bottom to top, i.e. from the outside towards the blind hole. This makes it possible to press the fourth region 44 of the holder 4a from below through the slot into the blind hole. The slot is elastically widened in the process. The fourth region 44 of the holder 4a cannot be easily removed from the blind hole through the slot or fall out.

[0060] The second module Mb also includes a module housing 2b. The module housing 2b of the second module Mb has the same cross-sectional profile as the module housing 2a of the first module. It differs primarily in its length. The module housing 2b of the second module Mb is longer than the module housing 2a of the first module Ma. This additional length is required to accommodate a reset mechanism R.

[0061] The return mechanism R serves to return the seal from a triggered state to a non-triggered state when the force triggering the seal is removed from the trigger 12.

[0062] Like the first module Ma, the second module Mb has a sliding part 3b. This sliding part has a flat, rod-like section 31 that extends over the entire length of the sliding part 3a and whose cross-section corresponds to that of the corresponding section 31 of the sliding part of the first module.

[0063] The flat, rod-like section 31 carries three structures 32, 33b, 34b on its underside.

[0064] The structure 32 at a trigger-side end of the sliding part 3b serves as a first connecting structure, which is provided for connecting the sliding part 3b of the second module Mb to the second connecting rod 9. Furthermore, the structure 32 is part of the overload mechanism of the first module Ma. The structure is identical to the corresponding structure 32 of the sliding part 3a of the first module Ma.

[0065] The structure 33b cooperates with the scissor mechanism Sb of the second module Mb and forms part of the overload mechanism Ub of the second module Mb. It also forms part of the return mechanism R.

[0066] The structure 34b serves as part of the return mechanism.

[0067] The structure 34b could also serve as a second connecting structure, which could serve to connect the sliding part 3b of the second module Mb to a further connecting rod 9, which is not provided in the embodiment.

[0068] The overload mechanism Üb of the second module Mb is designed in the same way as the overload mechanism Üa of the first module Ma.

[0069] The scissor mechanism Sb of the second module Mb is also designed in the same way as the scissor mechanism Sa of the first module.

[0070] In addition to the aforementioned structures 33 and 34, the return mechanism R comprises a holder 10 for a return spring 11 and the return spring 11. The holder 10 has a first fork-shaped portion 101 having two pins 1011 on its outer sides. These pins 1011 are inserted into holes in the module housing 2b of the second module Mb. As a result, the holder 10 is immovable relative to the module housing 2b.

[0071] This first area 101 is followed by a second area 102, onto which the return spring 11 is attached. The return spring 11 is a helical compression spring.

[0072] The second region is followed by a third region 103. This third region is guided in a blind hole in the structure 33b of the sliding part 3b. A lower boundary wall 331 of the blind hole has a slot that is open downwards. This slot tapers from bottom to top, i.e. from the outside towards the blind hole. This makes it possible to press the third region 103 of the holder 10 from below through the slot into the blind hole. The slot is elastically widened in the process. The third region 103 of the holder 10 cannot easily be removed from the blind hole through the slot or fall out. This secures the position of the return spring in the seal.

[0073] The connections between the trigger 12, the first connecting rod 8, the sliding part 3a of the first module Ma, the second connecting rod 9 and the sliding part 3b of the second module Mb are subjected to pressure both during triggering and during resetting, on the one hand by the pressure exerted on the trigger 12 and on the other hand by the pressure exerted by the return spring 11.

[0074] The movement of the unit comprising the trigger 12, the first connecting rod 8, the sliding part 3a of the first module Ma, the second connecting rod 9 and the sliding part 3b of the second module Mb, as well as the holders 4a, 4b for the overload springs, causes the free ends 612 of the long scissor elements 6a, 6b to move. As a result, these ends 612 are displaced relative to the housing 1 and the module housings 2a, 2b, and the pivotally mounted pins 71 of the short scissor elements 7a, 7b. The scissor mechanisms Sa, Sb open, and the sealing strip is thereby displaced downward.

[0075] If, for whatever reason, the sealing strip is prevented from fully moving downward, the overload mechanisms Ua, Ub, or one of them, will be activated. If the sealing strip is prevented from (further) moving downward, the scissor mechanisms Sa, Sb cannot open further. The free ends 612 of the long scissor elements 6a, 6b cannot then be moved together with the unit consisting of the trigger 12, the first connecting rod 8, the sliding part 3a of the first module Ma, the second connecting rod 9, and the sliding part 3b of the second module Mb.A continued movement of the unit consisting of the trigger 12, the first connecting rod 8, the sliding part 3a of the first module Ma, the second connecting rod 9, and the sliding part 3b of the second module Mb despite the standstill of the sealing strip then causes the free ends 612 of the long scissor elements 6a, 6b to press against the holders 4a, 4b for the overload springs 5a, 5b, and these are displaced towards the trigger 12. This compresses the overload springs 5a, 5b.

[0076] Advantageously, the distance by which the free ends 612 can be displaced against the overload spring 5a, 5b is exactly the same as the distance by which the unit comprising the trigger 12, the first connecting rod 8, the sliding part 3a of the first module Ma, the second connecting rod 9, and the sliding part 3b of the second module Mb can be displaced. The scissor mechanisms Sa, Sb are then protected against damage due to an overload.

[0077] At the Fig. 21 In the variant of the embodiment described above, the reset mechanism R is not provided in the second module Mb, but in the first module Ma. This has the advantage that the scissor mechanism Sb could be arranged at the end of the seal remote from the trigger. This can ensure greater pressure on the sealing strip at its remote end, which can be particularly important for the seal's impact resistance. 1 Housing 2a Module housing of the first module 2b Module housing of the second module 3a Sliding part of the first module 3b Sliding part of the second module 4a Holder for the overload spring of the first module 4b Holder for the overload spring of the second module 5a Overload spring of the first module 5b Overload spring of the second module 6a Long scissor element of the scissor mechanism of the first module 6b Long scissor element of the scissor mechanism of the second module 7 Short scissor element of the scissor mechanism of the first module 7b Short scissor element of the scissor mechanism of the second module 8 First connecting rod 9 Second connecting rod 10 Holder for the return spring 11 Return spring 12 Trigger 13 Holding profile 14 Sealing profile Mafirst module Mbsecond module SaScissor mechanism of the first module SbScissor mechanism of the second module UaOverload mechanism UbOverload mechanism RReset mechanism

Claims

1. st Second scissor element for a scissor mechanism (Sa, Sb) for a seal with a lowerable sealing strip (13, 14), wherein the scissor mechanism (Sa, Sb) has a first scissor element (6a, 6b) and the second scissor element (7a, 7b) which are mounted pivotably on one another, characterized in that the second scissor element is of substantially H-shaped form and is of integral design.

2. nd Second scissor element (7a, 7b) according to Claim 1, characterized in that the second scissor element (7a, 7b) has a connecting web (72) from which two arms (73) and two legs (74) extend.

3. rd Second scissor element (7a, 7b) according to Claim 2, characterized in that the second scissor element (7a, 7b) has two pins (71) which project outwards in opposite directions at the ends of the arms (73).

4. th Second scissor element (7a, 7b) according to Claim 3, characterized in that the second scissor element (7a, 7b) has two pins (75) which project inwards in opposite directions at the ends of the legs (74).