Patent Publication Number: US-10317092-B2

Title: Horizontal hinge for a household appliance door

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the priority of European Patent Application, Serial No. EP 16290135, filed Jul. 15, 2016, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference in its entirety as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a horizontal hinge for a domestic appliance door, in particular a cooking appliance door. The invention further relates to a domestic cooking appliance and to a method for mounting a horizontal hinge. The invention is, in particular, advantageously able to be used on horizontal hinges for oven doors, in particular on heavy-duty horizontal hinges. 
     BRIEF SUMMARY OF THE INVENTION 
     It would be desirable and advantageous to provide an improved horizontal hinge for domestic appliance doors to obviate prior art shortcomings. 
     According to one aspect of the present invention, a horizontal hinge for a cooking appliance door includes a hinge housing having a front face and a rear face, a rotatable hinge arm protruding from the front face of the hinge housing for retaining the cooking appliance door, a lifting rod protruding from the rear face of the hinge housing and coupled to the hinge arm, the lifting rod being pivotable when the hinge arm is caused to rotate, a compression spring placed over the lifting rod outside the hinge housing and held under compressive stress between the hinge housing and a bearing portion of the lifting rod, and an element (hereinafter denoted in general as “tilting element”) tiltably bearing against the hinge housing between the compression spring and the hinge housing. 
     This horizontal hinge has the advantage that the tilting element, against which the compression spring presses, is fully adapted to the angular alterations of the lifting rod when rotating the cooking appliance door and thus the hinge arm, by its own pivoting or rotation relative to the hinge housing. The tilting element is thus entrained with the rotation of the lifting rod. Thus the first end of the compression spring facing the tilting element is no longer bent against the length of the compression spring. As a result, in all positions of the lifting rod the compression spring remains entirely straight and undesirable friction is not produced on the lifting rod and thus force losses are also no longer produced. Noise which could occur by the sliding of the compression spring on the lifting rod is additionally avoided. 
     The compression spring may be a spiral spring. It may bear with a first end on the coupling element and with its second end on the bearing portion of the lifting rod. The first end and/or the second end may be surface ground in order to achieve a rectilinearity of the compression spring in a particularly reliable manner. The compression spring may be supported directly or indirectly, for example via an intermediate element. The lifting rod may run through the spiral spring and/or the spiral spring may be positioned on the lifting rod. 
     The hinge arm may be inserted into the cooking appliance door. The hinge arm is, in particular, rotatable about a horizontal rotational axis. 
     It may be understood by the lifting rod being coupled to the hinge arm that it is directly articulated to the hinge arm or that it is indirectly coupled to the hinge arm via a force transmission mechanism (for example an intermediate part guided in the hinge housing). If the cooking appliance door is rotated with the hinge arm, the lifting rod may also rotate (in a vertical plane, not about its own axis). In this case, with an opening procedure or a closing procedure any angular alteration of the hinge arm does not need to effect an angular alteration of the lifting rod, however angular ranges of the opening angle of the hinge arm may also be present in which the angle of the lifting rod is practically unaltered. 
     The bearing portion of the lifting rod corresponds to a stop or a support for the second end of the compression spring remote from the hinge housing. 
     It may be understood by the compression spring being held under compressive stress that, in the position of the hinge arm in which the compression spring is relaxed to a maximum extent (for example in a closed position of the hinge arm), the compression spring is fully relaxed. 
     The tilting element may bear directly (i.e. in direct contact) or indirectly (i.e. via at least one intermediate element) against the hinge housing. 
     It may be understood by the tilting element being tiltably supported that it is pivotable or tiltable relative to an outer surface of the hinge housing and namely in particular steplessly. The tilting angle which is able to be adopted may, in particular, correspond to the angles of the lifting rod. An advantageous development for reliably keeping the compression spring straight is that the tilting element is not attached at the side. 
     According to another advantageous feature of the present invention, the tilting element can be or can include a disk (“washer”) which in the center has a continuous projecting web, which web faces the hinge housing. Such a washer is robust and compact. It is additionally able to be produced in a particularly simple manner, for example by reshaping a conventional washer, for example by deep-drawing. Such a washer may also be denoted as a “rocker disk”. The aforementioned web faces the hinge housing whilst the compression spring is able to bear against the other side of the washer. The web thus provides the (linear) bearing surface relative to the hinge housing, the washer being pivotable about the bearing surface. 
     In principle, on the side of the tilting element, in particular of a washer, facing the hinge housing, differently shaped projections may also be present as a bearing surface or contact elements relative to the hinge housing. Thus, for example, instead of a web, two or more punctiform projections arranged in series may be present, etc. 
     According to another advantageous feature of the present invention, an intermediate element can be placed between the tilting element and the hinge housing. This may advantageously serve to maintain the bearing point of the tilting element accurately and permanently. Also, wear between the tilting element and the hinge housing may be prevented by means of the intermediate element. Moreover, noise produced by tilting the tilting element may thus be reliably avoided. 
     The intermediate element is advantageously made of plastic, since the plastic is able to elastically deform, and thus is able to dissipate force peaks between the tilting element and the hinge housing which may lead to wear and noise. Additionally, an intermediate element is able to be produced particularly cost-effectively from plastic. 
     The intermediate element may bear loosely against the hinge housing and, in particular, slide on the hinge housing. The intermediate element may have an annular basic shape, so that in particular the lifting rod may extend through the intermediate element. 
     According to another advantageous feature of the present invention, the intermediate element can include a latching groove for inserting the web of the washer. This configuration is in particular advantageous when using a rocker disk. The latching groove permits a particularly accurate positioning of the web. If the tilting element were to have differently shaped bearing projections, the intermediate element could also comprise differently shaped recesses or indentations for receiving the bearing projections. 
     According to another advantageous feature of the present invention, the web may only be partially introduced into the latching groove in order not to hinder a tilting of the rocker disk. If the intermediate element is made of sufficiently flexible material, for example plastic, the web may also be fully introduced into the latching groove. The washer may then bear with its side facing the hinge housing flat against the intermediate element. When rotating and/or pivoting the lifting rod and thus also the compression spring, the intermediate element may be sufficiently firmly pressed in for the rocker element to remain pivotable, such that the compression spring remains straight and does not buckle. 
     According to another advantageous feature of the present invention, the tilting element, in particular the rocker disk, can be shaped in an edge region (in particular on the outer face) with an anti-twist protection insert for engagement by the intermediate element. As a result, the tilting element is particularly reliably prevented from twisting (for example according to the “poka-yoke” principle). This is particularly advantageous in order to hold the alignment of the web parallel to the tilt axis or rotational axis of the tilting element, which in turn also assists easy tilting of the compression spring over the long term. Moreover, a reliable radial centering of the tilting element may be achieved relative to the lifting rod, whereby it is ensured that the tilting element does not come into contact with the lifting rod. This in turn prevents friction between the tilting element and the lifting rod, further assisting a spring movement without friction and noise prevention. The shaping of the edge region may be implemented, for example, by means of at least one radial recess or projection in the edge region, for example by a plurality (for example three or four) angularly offset recesses. The intermediate element may comprise at least one projection which is oriented in the direction of the tilting element (for example a tab, also denoted as centering clip) and which engages in the corresponding recess or passes through the recess. 
     According to another advantageous feature of the present invention, the intermediate element can include a plurality of projections which are oriented in the direction of the tilting element and which surround the compression spring on the outer face. These projections may serve for anti-twist protection (for example according to the “poka-yoke” principle) and/or as protection from radial displacement of the tilting element as already set forth above. By the extension to the side of the compression spring, alternatively or additionally a radial centering of the compression spring is achieved. As a result, the projections may surround the compression spring on the outer face for the centering thereof. This further improves a spring movement without friction, in particular also over the long term. The projections may be of tab-like configuration and also denoted as centering clips. 
     The projections can be configured differently which may facilitate an engagement with the tilting element. For example, the intermediate element may comprise a plurality of pairs of opposing projections (for example two pairs with a total of four projections), wherein the tabs of one pair are shaped equally and the tabs of different pairs are shaped differently. For example, the tabs of one pair in each case may comprise an integral projection whilst the tabs of a different pair are divided in two and/or have a slot. Alternatively, all projections may be configured equally. 
     The lifting rod can be made of metal so that it may be configured in a particularly stable manner. 
     According to another advantageous feature of the present invention, the lifting rod can include a cavity located along its longitudinal extent. This provides the advantage that the cavity is able to be used as receiver space for further functional elements which do not then require any further constructional space. The lifting rod may, for example, have a hollow cylindrical basic shape. The cavity may be open on the front face facing the hinge housing for the particularly easy introduction of a functional element or open on the front face remote from the hinge housing or open on both front faces. Also, by means of the cavity weight may be saved without noticeably reducing the mechanical stability. 
     The lifting rod can include at least one longitudinal slot. Thus even more weight may be saved. The longitudinal slot constitutes a through-hole between the cavity and the surroundings of the lifting rod. In order to keep the loss of stability of the lifting rod particularly low, the at least one longitudinal slot is arranged in a pivoting plane of the lifting rod, for example on a lower face or on an upper face. Additionally, the at least one longitudinal slot may be used in order to introduce or to pass through a functional element located into the cavity. As a result, the functional element may be prevented from twisting. Moreover, the compression spring is thus able to be supported on the functional element, whereby the buckling of the compression spring may be prevented in an even more reliable manner. If a contact surface between the functional element and the spring consists of plastic, noise produced by the compression spring sliding on the functional element may be kept low, in particular practically avoided. 
     According to another advantageous feature of the present invention, the lifting rod can include two—in particular opposing—longitudinal slots. The weight saving may be further increased thereby. Moreover, the compression spring is now optionally able to be supported on both sides on the functional element, whereby the buckling of the compression spring may be prevented in an even more reliable manner and in addition to reducing noise a radial centering of the compression spring is achieved which prevents in a particularly reliable manner the sliding of the compression spring directly on the lifting rod, and namely in both pivoting directions. The lifting rod may, for example, comprise and/or consist of two hollow cylindrical longitudinal sections arranged mirror-symmetrically to one another and spaced apart from one another by the longitudinal slot (also able to be denoted as lifting-guide rods). 
     According to another advantageous feature of the present invention, a functional element accommodated in the cavity can be a shock absorber. Thus a movement of the door may be damped for improved handling during a movement procedure. An associated shock absorber housing may protrude through the at least one longitudinal slot from the lifting rod, in order to prevent a twisting of the shock absorber and to serve as a support for the compression spring. The function as a spring support may serve for spring centering, spring support and for providing a sliding surface for the spring windings. At least one contact surface of the shock absorber housing advantageously consists of plastic, in order to keep the sliding friction with the compression spring and as a result the sliding noise low. The shock absorber housing may consist entirely of plastic. 
     According to another advantageous feature of the present invention, the compression spring can bear with its second spring end remote from the hinge housing against a terminal element. This permits a particularly reliable support and a particularly linear retention of the compression spring on the lifting rod. The bearing portion of the lifting rod thus has a terminal element or may be configured as a terminal element. 
     The terminal element may be a disk (“swinging disk”). The terminal element may alternatively be a limiting part inserted into the lifting rod (also able to be denoted as a spring stop or locking wedge), for example a sheet metal part. The spring stop may be latchable and/or latched into the lifting rod. By selecting the width of the spring stop (in the longitudinal direction of the lifting rod) a spring pretensioning may be adjusted in a simple manner. In particular, a fine calibration may be undertaken in a simple manner in a final inspection and compensation of production tolerances (spring/mechanism) carried out. 
     According to another advantageous feature of the present invention, the terminal element (in particular if it is configured as a spring stop) on its edge facing the compression spring can include centering chamfers in order to center the compression spring radially. The centering chamfers may bear on the inner face against the compression spring and/or penetrate the compression spring. As a result, a lateral or radial positive connection is achieved between the compression spring and the spring stop. 
     According to another advantageous feature of the present invention, the terminal element (in particular if it is configured as a spring stop) on its edge remote from the compression spring can include further centering chamfers in order to position the spring stop accurately on the lifting rod and/or the two lifting guide rods. The further centering chamfers may also serve for preventing the lifting rod from sliding out. The further centering chamfers may be configured as notches. 
     According to another advantageous feature of the present invention, a vertical swing distance of a second spring end of the compression spring remote from the hinge housing can be between 40 mm and 60 mm. 
     According to another aspect of the present invention, a domestic appliance can include a domestic appliance door and at least such a horizontal hinge connected to the domestic appliance door configured for allowing the domestic appliance door to close a loading opening. For example, the domestic appliance may be a domestic cooking appliance which includes a cooking chamber having a loading opening, a horizontally pivotable cooking appliance door configured for closing the loading opening, and a horizontal hinge connected to the cooking appliance door, the horizontal hinge comprising a hinge housing having a front face and a rear face, a rotatable hinge arm protruding from the front face of the hinge housing for retaining the cooking appliance door, a lifting rod protruding from the rear face of the hinge housing and coupled to the hinge arm, the lifting rod being pivotable when the hinge arm is caused to rotate, a compression spring placed over the lifting rod outside the hinge housing and held under compressive stress between the hinge housing and a bearing portion of the lifting rod, and a tilting element tiltably bearing against the hinge housing between the compression spring and the hinge housing. 
     The domestic appliance may be configured in a similar manner to the horizontal hinge and has the same advantages. 
     As described above, the domestic appliance door can be a cooking appliance door, in particular an oven door. Advantageously, the domestic appliance door is connected to two horizontal hinges, which may, for example, be arranged to the left and right of the loading opening of a treatment chamber of the associated domestic appliance. The treatment chamber may be a cooking chamber or a further food preparation chamber, for example an oven chamber. 
     According to still another aspect of the present invention, a method for mounting a horizontal hinge includes feeding a tilting element over a lifting rod in a direction of a hinge housing, feeding a compression spring over the lifting rod, and fastening a terminal element to the lifting rod such that a hinge-housing-remote end of the compression spring bears against the terminal element to thereby tension the compression spring. The method may be configured in a similar manner to the horizontal hinge and/or to the domestic cooking appliance and has the same advantages. 
     According to another advantageous feature of the present invention, an intermediate element made of plastic can be placed between the tilting element and the hinge housing, wherein feeding the tilting element over the lifting rod includes engaging a front web of the tilting element in a latching groove of the intermediate element. The tilting element may be configured as a washer which in the center has the web in the form of a continuous projecting web. The washer is fed with its projecting web at the front in the direction of the intermediate element until the projecting web engages in the latching groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above described properties, features and advantages of this invention and the manner in which they are achieved become clearer and significantly more comprehensible in connection with the following schematic description of an exemplary embodiment which is described in more detail in connection with the drawings. 
         FIG. 1A  shows as a sectional drawing in side view a detail of a domestic cooking appliance with a horizontal hinge according to a first exemplary embodiment in an open position; 
         FIG. 1B  shows as a sectional drawing in side view a detail of the domestic cooking appliance according to  FIG. 1A  with the horizontal hinge according to the first exemplary embodiment in a closed position; 
         FIG. 2A  shows in an oblique view a tilting element of the horizontal hinge according to the first exemplary embodiment; 
         FIG. 2B  shows in an oblique view a detail of the horizontal hinge according to the first exemplary embodiment in the region of the tilting element; 
         FIG. 3  shows in an oblique view a horizontal hinge according to a second exemplary embodiment in a closed position; 
         FIG. 4A  shows in an oblique view a detail of the horizontal hinge according to the second exemplary embodiment in the region of a hinge housing without a compression spring; 
         FIG. 4B  shows in a further oblique view a detail of the horizontal hinge according to the second exemplary embodiment in the region of a lifting rod without the compression spring; 
         FIG. 5A  shows in an oblique view a terminal element of the horizontal hinge according to the second exemplary embodiment; 
         FIG. 5B  shows in a plan view a detail of the horizontal hinge according to the second exemplary embodiment in the region of the terminal element; 
         FIG. 6A  shows as a sectional drawing in side view a detail of a further domestic cooking appliance in an open position; and 
         FIG. 6B  shows as a sectional drawing in side view a detail of the further domestic cooking appliance in a closed position. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION 
     Turning now to the drawing, and in particular to  FIG. 6A , there is shown a sectional drawing in side view a detail of an exemplary domestic cooking appliance  101 , for example an oven, which includes a cooking chamber G with a loading opening  102  on the front face. The loading opening  102  is able to be closed by a horizontally pivotable cooking appliance door  103 , which is connected to at least one horizontal hinge  104 . The horizontal hinge  104  is shown in an open position in which the door  103  opens up the loading opening  102 . The horizontal hinge  104  has a rotatable hinge arm  106  protruding from the front face of a hinge housing  105  for retaining the cooking appliance door  103 . The horizontal hinge  104  further includes a lifting rod  107  protruding from the rear face of the hinge housing  105  and mechanically coupled to the hinge arm  106 . For coupling to the hinge arm  106 , a portion of the lifting rod  107  located in a hinge housing  105  is rotatably connected to an intermediate part  108  which is also rotatably connected to the hinge arm  106 . The intermediate part  108  is able to be guided by means of the hinge housing  105 . A spring (compression spring  109 ) is placed over and/or positioned on the portion of the lifting rod  107  located outside the hinge housing  105 . The compression spring  109  bears with its first end (proximal end relative to the hinge housing  105 ) against the hinge housing  105  and with its second end remote from the hinge housing  105  (distal end relative to the hinge housing) against a support disk (“swinging disk”  110 ) connected to the lifting rod  107 . The support disk  110  thus used as a terminal element forms a bearing portion of the lifting rod  107 . The compression spring  109  is under compressive stress. Since in the open position the lifting rod  107  is oriented obliquely downwardly, starting from the intermediate part  108 , this leads to a bending of the compression spring  109  which as a result comes into contact with the lifting rod  107  on the lower face. 
       FIG. 6B  shows the domestic cooking appliance  101  in a view similar to  FIG. 6A  with the horizontal hinge  104  in a closed position in which the cooking appliance door  103  closes the loading opening  102 . By rotating the hinge arm  106 , the intermediate part  108  in the hinge housing  105  is displaced and rotated and the lifting rod  107  is correspondingly moved. More specifically, the lifting rod  107  has been rotated counterclockwise so that starting from the intermediate part  108  it is now oriented obliquely upwardly. This leads to the bending of the compression spring  109  in the other direction, therefore, whereby the compression spring now comes into contact with the lifting rod  107  on the upper face. Additionally, the lifting rod  107  now protrudes further out of the hinge housing  105  so that the compression spring  109  is under less compressive stress. The corresponding energy loss in the compression spring  109  is used for assisting the movement of the door from the open position into the closed position. Conversely, the compression spring  109  dampens an opening movement of the cooking appliance door  103  by energy absorption. 
     The contact of the lifting rod  107  by the biased compression spring  109  leads to uncontrolled friction and thus to force losses when the cooking appliance door  103  is moved. It may also lead to noise being produced (creaking, squeaking) when the cooking appliance door  103  is moved. 
     To address the problem of force loss and noise, reference is now made to  FIG. 1A  which shows as a sectional drawing in side view a detail of a domestic cooking appliance  1  with a horizontal hinge  2  in an open position. The domestic cooking appliance  1  differs from the domestic appliance  101  in that on the horizontal hinge  2  a tilting element  3  bearing tiltably against the hinge housing  105  is present between the compression spring  109 —configured as a spiral spring—and the hinge housing  105 . The tilting element  3  is automatically adjusted to a tilt angle relative to the hinge housing  105 , such that the compression spring  109  is compressed in a rectilinear manner between the tilting element  3  and the swinging disk  110 . To this end, the compression spring  109  bears with a first (proximal) spring end  109   a  against the tilting element  3  and bears with its second (distal) spring end  109   b  against the swinging disk  110 . At least one of the spring ends  109   a  and/or  109   b  may be surface ground. 
     In particular, it is possible for the tilting element  3  to have been fed over the lifting rod  107  in the direction of the hinge housing  105 , then the compression spring  109  to have been fed with its first spring end  109   a  at the front over the lifting rod  107  and then the swinging disk  110  to have been fastened to the lifting rod  107  so that the compression spring  109  is tensioned. 
       FIG. 1B  shows the domestic cooking appliance  1  with the horizontal hinge  2  in a closed position. The tilting element  3  has participated in the rotation of the lifting rod  107  and the compression spring  109  and correspondingly adapted its tilting relative to the hinge housing  105 , so that now the compression spring  109  is rectilinear and namely aligned parallel to the lifting rod  107 . A vertical swing distance of the second spring end  109   b  between the open position and the closed position is ca. 50 mm. 
       FIG. 2A  shows in an oblique view a possible tilting element  3  of the horizontal hinge  2 . The tilting element  3  is a washer  4  which in the center has a continuous projecting web  5 . The web  5 , for example, may have been introduced by deep-drawing. The web  5  protrudes toward a front face  4   a  facing the hinge housing  105 . The web  5  has been produced by deep-drawing so that a notch  6  is present on the rear face  4   b , not shown, of the washer, which does not limit the functionality of the tilting element  3 . The tilting element  3  may optionally comprise lateral recesses  13  in the outer edge region of the washer  4  (see also  FIG. 4A ). 
       FIG. 2B  shows in an oblique view a detail of the horizontal hinge  2  in the region of the tilting element  3 . An intermediate element  7  which is made of plastic and which has an elongate indentation or “latching groove”  8  for the at least partial introduction of the web  5  of the washer  4  may be present between the washer  4  and the hinge housing  105 . The web  5  penetrates or engages in the latching groove  8 . The intermediate element  7  is sufficiently flexible that the front face  4   a  of the washer  4  is able to bear flat thereagainst without noticeably impairing the tiltability of the washer  4 . However, a previously introduced latching groove  8  may also be dispensed with, the web  5  then pressing for example into the intermediate element  7  such that here a corresponding indentation is produced. 
       FIG. 3  shows in an oblique view a horizontal hinge  9  in a closed position. The horizontal hinge  9  may also be used in the domestic cooking appliance  1 . The horizontal hinge  9  is constructed in a similar manner to the horizontal hinge  2 , wherein however now the intermediate element  10  on the outer face additionally has four tab-like projections  12  protruding to the side in the direction of a tilting element  11  and/or the compression spring  109 . The projections  12  are angularly offset by 90° in the peripheral direction. The projections  12  are shown here configured as simple tabs; but for example two opposing projections  12  may also be configured in two parts, for example with a central slot (not shown). 
     As shown more clearly in  FIG. 4A , the projections  12  extend in suitable lateral recesses  13  in the outer edge region of the tilting element  11 , also configured here as washer  4 . As a result, an anti-twist protection insert for the tilting element  11  is produced, whereby in particular the web  5  is not able to twist. Also, the tilting element  11  is no longer able to be laterally or radially uncentered, so that the projections  12  also serve as centering elements for the tilting element  11 . 
     However, the projections  12  extend further, namely beyond the tilting element  11  to the side over the compression spring  109  as shown in  FIG. 3 . As a result, they act as optionally resilient, lateral limits for the compression spring  109  and consequently also as centering elements for the radial centering of the compression spring  109 . As a result, the compression spring  109  is prevented from being able to slide at its first proximal end region  109   a  on a lifting rod  14 . 
     As also shown more clearly in  FIG. 4B , the lifting rod  14  is configured in two parts with two lifting guide rods  15  and  16  which are aligned in parallel and mirror-symmetrically with one another. The lifting guide rods  15  and  16  have a circular sector-shaped cross-section and are spaced apart from one another by means of continuous longitudinal slots  17  on the upper face and lower face. The lifting guide rods  15  and  16  additionally define a cylindrical central cavity  18 , a shock absorber  19  being accommodated therein. The shock absorber  19  has a shock absorber housing  20  made of plastic which protrudes from the inside through the longitudinal slot  17  to the outside, laterally from the lifting rod  14  and/or the lifting guide rods  15  and  16 . The shock absorber housing  20  may protect the compression spring  109  further against buckling and additionally prevent the compression spring  109  from sliding directly with its central portion on the lifting rod  14  which is, for example, made of metal. The shock absorber housing  20  may thus serve as an internal support and a low-friction sliding surface for the compression spring  109 . 
     In the region of the second distal end  109   b  of the compression spring  109  and/or the lifting rod  14  in each case short slotted through-holes  21  are located in the lifting guide rods  15  and  16  in the left and right side thereof. Once again with reference to  FIG. 3  these through-holes  21  serve for inserting and holding a terminal element in the form of a locking wedge or spring stop  22 . 
     Now with reference again to  FIG. 4A , the lifting guide rods  15  and  16  also extend through the intermediate element  10 . 
       FIG. 5A  shows the spring stop  22  in an oblique view.  FIG. 5B  shows in a plan view a detail of the distal end region of the lifting rod  14  with the inserted spring stop  22  and compression spring  109 . 
     The spring stop  22  is, for example, a stamped-out sheet metal part which is inserted into the through-holes  21  when the compression spring  109  is compressed, after which the compression spring  109  is relaxed. The relaxed compression spring  109  presses with its distal end  109   b  on the spring stop  22 . The spring stop  22  thus serves as a rearward stop for the compression spring  109  and for the securing thereof is in turn pressed by means of the compression spring  109  onto the lifting guide rods  15  and  16 . 
     The spring stop  22  has a front tip or nose  23  which penetrates the compression spring  109  on the inner face and which merges into a wider main region  24  in a rearward direction. An internal diameter of the compression spring  109  is wider than the nose  23  but narrower than the main region  24  so that the distal end  109   b  of the compression spring  109  bears against the main region  24 . 
     The lateral edges of the nose  23  are configured as first centering chamfers  25  extending obliquely to the front, in order to permit a particularly accurate centering of the distal end  109   b  of the compression spring  109  and easy penetration into the compression spring  109  during mounting. 
     The spring stop  22  has on its rear edge two notches or second centering chamfers  26  in order to come into engagement with the lifting guide rods  15  and  16  and, as a result, to latch the spring stop  22  with the lifting guide rods  15  and  16 . Thus the spring stop  22  is prevented from sliding laterally out of the through-holes  21  and the distal end  109   b  of the compression spring  109  may be centered against the lifting rod  14 . 
     A spacing d in the longitudinal direction of the compression spring  109  and/or the lifting rod  14  between a base of the centering chamfers  26  and a transition between the nose  23  and the main region  24  (also able to be denoted as the thickness of the spring stop  22 ) may be varied in order to adjust in a simple manner a pretensioning of the compression spring  109 , for example for fine calibration during final assembly. 
     Naturally the present invention is not limited to the exemplary embodiment shown. 
     Generally, an individual item or a plurality of items may be understood by “a” “an”, etc., in particular in the sense of “at least one” or “one or more”, etc. as long as this is not explicitly excluded, for example by the expression “just one”, etc. 
     In addition, numerical information may encompass just the specified number and the usual tolerance range, as long as this is not explicitly excluded.