Abstract:
A joint or articulation ( 1 ), especially for connecting sidepieces of a multi-purpose ladder that can be folded up, has two joint legs ( 2, 3 ) that are pivotable relative to one another about a joint shaft ( 4 ). One of the joint legs ( 2 ) forms an outer joint portion having outer shells ( 7 ) and a joint connector ( 8 ), while the other joint leg ( 3 ) is embodied as an inner joint portion having inner disks ( 9 ) and joint connectors ( 10 ). A spring-loaded locking member ( 24 ) is movable essentially radially or tangentially relative to the joint shaft ( 4 ) and is engageable in at least one recessed portion ( 42 ) of one joint leg ( 2 ). In order to achieve a simpler construction of the joint or articulation ( 1 ), recessed portions ( 12 ) are provided in the inner disk ( 9 ), whereby the locking member ( 24 ) extends transverse to the plane of the inner disk through the recessed portions ( 12 ). The locking member ( 24 ) cooperates with a lever ( 20 ) that is pivotable about a journal ( 19 ) that is spaced from the joint shaft ( 4 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an articulation or joint, especially for connecting sidepieces of a multi-purpose ladder that can be folded up. 
     DE 32 11 164 C2 describes a multi-purpose ladder that can be folded together, the sidepieces of which are connected by joints or articulations that are disposed in pairs and can be locked in a number of working positions. Each of these joints has two joint portions that are pivotable about a common joint shaft, whereby one of these joint portions forms a dual-shell locking disk. In the vicinity of its periphery, this locking disk has grooves that are distributed in conformity with the operating positions. Engaging into this grooves is a spring-loaded locking piece that can be raised out of the grooves for the purpose of pivoting the joint portions. This locking piece comprises a locking bar having an essentially rectangular cross-sectional configuration; the height of the locking bar is approximately equal to the width of the second joint portion. The locking piece is guided in a recessed portion in the side walls of the second joint portion, and includes a guide part that adjoins the locking bar, with the height of the guide bar being only slightly less than the height of the second joint portion, whereby the width is greater than the width of the recessed portion. In order to return the locking piece into the locking position, an abutment is provided for the return spring. The locking piece can be raised out of the respective groove of the locking disk by means of a release lever that is pivotably mounted on the second joint portion and is connected with an actuating lever. The release levers of the joints associated with the two sidepieces are interconnected by a rod, so that an unlocking of the locking pieces of the paired joints can be simultaneously activated. The recessed portion has sections of different width, so that a deposition surface is formed in which the locking bar is held in its disengaged position. The locking disk, which is provided with grooves, is provided with projections disposed next to the grooves that serve as abutment surfaces for the locking bar of the locking piece, so that the locking piece is pressed from the deposition surface in the direction of folding-together of the sidepieces, and hence automatically engages in the groove. 
     It is an object of the present invention to provide a joint or articulation that has a straightforward construction and is economical to produce. 
     SUMMARY OF THE INVENTION 
     This object is inventively realized by a joint or articulation having the features: two joint legs that are pivotable relative to one another about a joint shaft, wherein each of the legs comprises a pair of shaped parts, wherein one of the joint legs forms an outer joint portion having outer shells and a joint connector, and the other joint leg is embodied as an inner joint portion having inner disks and joint connectors, and wherein recessed portions are provided in the inner disks; at least one spring-loaded locking member that is movable essentially radially or tangentially relative to the joint shaft, and is engageable in at least one further recessed portion of the one joint leg, wherein the locking member extends transverse to the plane of the inner disks through the recessed portions thereof; and a lever that is pivotable about a journal that is spaced from the joint shaft, wherein the locking member cooperates with the lever. 
     A number of advantages of the present invention can be seen in that while maintaining all required functions and fulfilling the safety regulations, the joint or articulation comprises an extremely small number of individual parts, and these parts can be manufactured and assembled in a simple manner. Furthermore, the movable elements, such as locking member and lever, as well as the recessed portions required for engagement of the locking member, are disposed in an essentially enclosed region within the outer shell, so that the joint or articulation is well-protected from dirt or contamination. Merely the slots for the locking members are open toward the outside, and a gripping element or activation knob or possibly a rod for activation with one hand at both sides are located as movable elements outside the joint. 
     Pursuant to one preferred specific embodiment of the basic concept of the present invention, the lever is disposed beyond the contour of the outer shell in a region adjacent to the joint connector between the inner disks, whereby this lever cooperates with one end of a locking slide that carries at least one locking member. In this way, the form of the required parts is further simplified, whereby the locking slide, while comprising a single piece, can also include two locking members that are preferably aligned with one another. In this way, the respective requirements for transmitting forces can be handled not only by the strength of the materials used, but also by the number of locking members. In order to produce an appropriate return force, a spring is preferably provided that is disposed between the inner disks and that acts with one end upon the locking slide. Such a spring is preferably a flat spring or a helical spring, which engages a bent section of the locking slide. 
     Pursuant to a first modified embodiment, the lever is mounted in the joint connector of the inner joint portion, whereby the pivot axis of the lever extends parallel to the joint shaft. In this connection, it is expedient that the lever includes a cover or guide part that is pivotable between the joint connectors, and at least one actuation element that is carried thereby as well as a journal bushing, whereby the actuating elements project outwardly through an opening in the joint connectors. With such an embodiment, due to the defined spacing of the parts of the joint connector that accommodate the lever between them, and which joint connector corresponds to the thickness of the cover or guide part with appropriate play, a pivoting of the lever that is free of jamming is ensured, and the penetration of dirt is avoided. Between the actuating element and the journal bushing there is provided a cutout in the lever in which the hook of the locking slide is suspended. In this way, a positive connection is provided between the lever and the locking slide. 
     In another embodiment of the invention, the lever is mounted in a cover secured to the inner joint portion, whereby the pivot axis of the lever extends perpendicular to the joint shaft. In this connection, a pressure or thrust plate that acts upon the lever is provided in the cover; the thrust plate is fixedly connected with a pin that is rotatably journaled in the joint shaft. This thrust plate serves for the unlocking of the joint, whereby the lever converts the movement of the thrust plate into a movement of the locking slide that extends transverse thereto. 
     In order during unfolding of the sidepieces of the ladder for the locking member to automatically engage or register in the recessed portions, a spring is expediently provided that interacts with the locking slide and biases the latter in the locking direction. The spring can, for example, be a flat or helical spring that is held by one end on the inner disk. 
     Since for unlocking or locking the locking member is moved essentially radially relative to the joint shaft, the recessed portions in the inner disks also extend essentially radially. In each inner disk such recessed portions include a narrow section as well as a wider section that is disposed closer to the joint shaft, as well as a shoulder that is disposed between the two sections and against which the locking member can be supported. This shoulder serves for holding the locking member in the unlocked position, so that during folding together of the sidepieces of the ladder, the joint portions can be pivoted without the locking members engaging in intermediate recesses. So that this position of the locking member is maintained while the sidepieces of the ladder are folded together, yet is released in the opposite pivoting direction, it is advantageous to provide on glide surfaces, next to each recessed portion in the outer shell, a raised portion that is directed radially relative to the joint shaft, whereby in the direction of folding together of the joint connectors this raised portion has the shape of a ramp, and in the opposite direction has a steeply rising flank. This steeply rising flank acts as an abutment for the locking member, so that the latter is pressed away from the shoulder and hence can penetrate into the recessed portion in the outer shell. To the extent that the locking members of two joints or articulations on opposite sidepieces of a ladder are to be actuated together, a rod or handle that extends between the joints is provided. In this connection, it is advantageous to mount the ends of the rod in a mounting opening of each of the two joints formed on the inner joint portions thereof. The rod can be operatively connected directly with the actuating elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Specific embodiments of the invention will be described in greater detail subsequently with the aid of the drawings, in which 
     FIG. 1 is an exploded view of a joint or articulation, 
     FIGS. 2 a  to  2   c  show three different views of a locking slide, 
     FIGS. 3 a  to  3   c  show three different views of a lever, 
     FIG. 4 is an inner view of the joint or articulation with inner and outer joint portions and installed lever and locking slide in the locked state of the joint in the extended position, 
     FIG. 5 is a view according to FIG. 4 in the unlocked position and a position of the joint connectors in which they form a relatively acute angle, 
     FIG. 6 is an outer view of the joint according to FIG. 4 showing a rod for actuating the lever, 
     FIG. 7 is a view of the joint in accordance with the arrow VII in FIG. 6, 
     FIG. 8 is an exploded view of a second exemplary embodiment of an inventive joint or articulation, 
     FIGS. 9 a  to  9   b  show two different views of a lever, 
     FIG. 10 shows an outer view of the joint or articulation according to FIG. 8, 
     FIG. 11 is a cross-sectional view taken along the line XI—XI in FIG. 10 in the locked state, 
     FIG. 12 is a view according to FIG. 11 in the unlocked state, 
     FIG. 13 is a view according to the line XIII—XIII in FIG.  10 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The joint or articulation illustrated in the exploded view of FIG. 1 comprises an outer portion  5  and an inner portion  6 , whereby the outer portion  5  of the articulation or joint is formed from two outer shells  7  having joint connectors  8  and the inner portion  6  of the articulation or joint is formed from two inner disks  9  having joint connectors  10 . In an inwardly directed curvature, the outer shells  7  are provided with a central opening  34 , and the inner disks  9  are provided with a central opening  17  that is surrounded by a support; the openings are lined with one another and an articulation shaft  4  in the form of a bolt or rivet is guided through the openings. The outer joint portion  5  and the inner joint portion  6  are pivotable relative to one another about the articulation or joint shaft  4 . To increase the shape rigidity, the joint connectors  8  and  10  are provided with reinforcing creases  18 , and for the connection with a sidepiece of a ladder or the like are provided with openings  19 . 
     The outer shells  7  with the joint connectors  8  are mirror images of one another; the same is true for the inner disks  9  with the joint connectors  10 . The inner disks  9  are provided with a raised rim  37  along their periphery, so that a hollow space is formed between the two joined-together inner disks  9 . Disposed in this hollow space is a locking slide  20  that is shown in three views in FIGS. 2 a  to  2   c . As shown in FIGS. 2 a  to  2   c , the locking slide  20  is formed in one piece from a flat material, and includes two locking members  24  and  30 . Disposed between the locking members  24  and  30  are two bent sections  22 . On that end of the locking slide  20  disposed at the far side of the locking member  30  is a hook  23  that serves for the positive connection of the locking slide with a lever  25 . 
     As can be seen from FIGS. 3 a  to  3   c , the lever  25  includes a journal bushing  27  that is placed upon a journal pin  33  (FIG. 1) that is formed on the inner joint portion  6  by the deformation of material, and also includes a cover or guide part  29  that has the shape of a flat plate. Provided on the cover or guide part  29  is a cutout  28  for hooking in the hook  23  of the locking slide  20 . Also disposed on both flat sides of the guide part  29  are actuating elements  26  that project essentially at right angles out of the plane of the plate and have such a height that, as shown in FIG. 1, they extend all the way to the outside through openings  32  that are formed in supports  31  of the joint connector  10 . 
     To guide the locking slide  20  in the inner joint portion  6 , there is formed on the inner disks  9  a ring  43  that extends parallel to the rim  37  and in which recessed portions  12  and  16  are disposed that extend approximately radially relative to the rotation shaft  4 . A spring  11  is placed in the hollow space formed between the inner disks  9 ; the spring acts upon the locking slide  20  in a locking direction. 
     The outer shells  7  comprise a cover portion  40  and a circumferential rim  39 , and radially spaced therefrom a ring  36  directed toward the inner disks  9  is provided in which are disposed recessed portions  35 ,  42  that form radial slots. The locking members  24  and  30  can engage these recessed portions  35  and  42 , or, for unlocking purposes, can also be pressed out of these recessed portions. Instead of the ring  36 , ring segments having appropriate gaps can also be provided, whereby the gaps, which serve for receiving the locking members  24 ,  30 , have a comparable shape and size to the recessed portions  35 ,  42 . Formed on the radially inwardly disposed side of the rings  36 , which are shaped similar to arcs of a circle, is a glide surface  38  for the locking members  24  during pivoting of the joint parts. 
     FIG. 4 shows a joint or articulation  1  that comprises two legs  2  and  3 . The legs  2  and  3  of the joint or articulation include joint connectors  8  and  10  that are provided for being received in sidepieces of a ladder. The two joint legs  2  and  3  have a common joint axis or shaft  4 , and are pivotable relative to one another about this shaft. In FIG. 4, the outer shell  7  is shown covered, whereas the inner disk  9  of the joint leg  3  is visible. In addition, it can be seen that the spring  11  of the locking slide  20  is biased on one of its bent sections  22 , and in particular in a direction in which the locking member  24  is pressed into a narrow section  13  of the recessed portion  12 . The locking member  30  is disposed in the recessed portion  16 . The recessed portion  12  also includes a wider section  14  that is disposed further radially inwardly, as well as a shoulder  15  that is provided between the sections  13  and  14 . In this position of the locking slide  20 , the lever  25  is disposed in its end position toward the joint shaft  4 . In FIG. 4 the position of the journal pin  33  upon which the journal bushing  27  is placed is also visible. In other respects, the reference numerals for the same parts correspond with those of FIG.  1 . 
     Whereas FIG. 4 illustrates the joint or articulation  1  in the locked position in the extended position of the joint connectors  8 ,  10 , FIG. 5 illustrates the arrangement in the unlocked position, whereby the joint connectors  8  and  10  are pivoted toward one another and form an angle between them of about 30°. In this position, the locking slide  20  is pressed transverse to the joint shaft  4 , whereby the locking member  24  is moved toward the joint shaft  4 , and the locking member  30  is moved away from the joint shaft  4 . The locking slide  20  assumes this position when the lever  25  is pivoted in a counterclockwise direction about the journal pin  33 , which is effected with the aid of the actuating element  26  that projects out of the joint connector. If the locking member  24  is pressed entirely out of the narrow section  13  of the recessed portion  12  into the wider section  14 , the spring  11 , due to its force direction with which it acts upon the bent section  22 , moves the locking member  24  approximately in the circumferential direction of the joint  1 , so that the front edge of the locking member  24  comes to rest behind the shoulder  15 . In other respects, the reference numerals in FIG. 4 correspond for the same parts with those of the previously described figures. 
     From the outer view of the joint or articulation  1  shown in FIG. 6, the position of the recessed portions  35  and  42  for the engagement of the locking members of the locking slide becomes clear. In this connection,  35  designates those recessed portions in which the locking member  24  illustrated in FIGS. 4 and 5 engages, and  42  designates those recessed portions that are provided for the locking member  30 . Since the joint parts  5  and  6  illustrated in FIGS. 1,  4  and  5  are shaped sheet metal parts, the inner contours of the outer shell  7  are recognizable in FIG.  6 . Thus, it can be seen that the glide surface  38 , next to the recessed portions  35 , has a raised portion  44  that is directed radially toward the joint shaft  4  and that on one side is in the form of a shallowly rising ramp  45  and on the other side is formed as a steeply rising flank  46 . This steeply rising flank  46  extends at least nearly parallel to the radial direction, relative to the central opening  34  in the outer shell  7 . 
     If the joint or articulation was folded completely together, and if then the joint connectors  8  and  9  are again pivoted relative to one another, then upon reaching a first locking position, which can, for example, be achieved at an angle as shown in FIG. 5, the locking member  24  comes against the flank  46  of the raised portion  44 , so that the locking member  24  is pressed within the wide section  14  of the recessed portion  12  in such a way that the locking member locking  24  rests against the shoulder  15 . Due to the force of the spring  11 , the locking slide  20  is shifted, so that the locking member  24  is moved into the recessed portion  35  and the locking member  30  is moved into the recessed portion  42 . In this way, when the joint legs  2 ,  3  are pivoted apart, there is effected an automatic engagement of the locking members. FIG. 6 also shows a handle or rod  49  that interacts with the actuating element  26 , with this rod  49  being provided to facilitate actuation for pivoting of the lever  25 . The rod  49  can engage in the journal pin  33  if such journal pin  33  is hollow, for example by deformation of the sheet metal. Instead of the rod  49 , in order to be able to activate two joints or articulations with one hand, which joints are disposed in pairs on opposite sides on the sidepieces of a multipurpose ladder, suitable handles or rods are provided. 
     FIG. 7 is a view of the joint or articulation  1  taken in the direction of the arrow VII of FIG.  6 . It can be seen that two outer shells  7  form the outer joint portion  5 , and two inner disks  9  form the inner joint portion  6 . In other respects, the reference numerals in FIG. 7 correspond for the same parts with those of the previously described figures. 
     FIG. 8 is an exploded view of a second exemplary embodiment of the inventive joint or articulation. This joint or articulation  51  includes an outer portion  55  and an inner portion  56 . The outer portion  55  of the joint or articulation is formed from two outer shells  57  having joint connectors  58  adjoining thereon, with the configuration thereof being nearly identical to that of the outer shells  7  of FIG.  1 . The joint connectors  58  merely have no openings, but rather only reinforcing creases. The locking slide  20  and the spring  11  are identical to those of the embodiment of FIGS. 1 and 2 a  to  2   c . The guidance of the locking slide  20  is also effected in the inner joint portion  56  in the same manner as with the joint portion in FIG.  1 . The inner joint portion  56  is formed of two inner disks  59 , whereby in FIG. 8 the upper inner disk, i.e. a joint connector  60  adjoining thereon, is provided with a cutout  61 . An arm  62  of a lever  65 , which is shown in greater detail in FIGS. 9 a  and  9   b , projects through this cutout  61 . As can be seen, the lever  65  includes two arms  62  and  63 , each of which proceeds from a journal bushing  64  and essentially form an angle of about 9°. 
     The arm  62  serves for engaging in a recessed portion  74 , (FIGS. 11 and 12) between the hook  23  and the locking member  30 . The outer shells  57  also have central openings  34 , and the inner disks  59  have central openings  17 , through which a hollow rivet is guided as the joint shaft  54 . In addition, two screws or bolts  66  are provided that are inserted through screw holes  67  in the joint connector  60  in order to be screwed into threaded sleeves  68  on a cover  70 . This cover  70  covers the upper outer shell  57  and extends over a considerable portion of the joint connector  60 . The cover  70  has a bore  71  that serves for receiving a pressure or thrust plate  72  that is displaceable in the bore  71 . Disposed coaxially on the thrust plate  72  is a pin  73  that is guided in the hollow rivet that serves as the joint shaft  54 . 
     FIG. 10 shows a plan view on the joint or articulation  51 , which is comprised of two joint legs  52  and  53 . From this illustration the shape and extension of the cover  70  is recognizable, whereby the thrust plate  72  is disposed centrally relative to the essentially circular portion of the cover  70 . 
     FIG. 11 shows a cross-sectional view taken along the line XI—XI in FIG.  10 . From this, it can be seen that the journal bushing  64  of the lever  65  is mounted on a pin  69  in the cover  70 . The arm  63  of the lever  65  engages under this thrust plate  72 , whereas the arm  62  projects through the cutout  61  and engages in the recessed portion formed between the hook  23  and the locking member  30 . The locking member  30  is disposed in the recessed portion  42 , and the locking member  24  is disposed in the recessed portion  35 ; in other words, FIG. 11 shows the locked position. In this position, the thrust plate  72  assumes its upper end position, and the pin  73  is at least nearly flush with the underside of the joint or articulation  51 . 
     To unlock the joint or articulation  51 , the thrust plate  72  is pressed into the bore  71  of the cover  70 , as illustrated in FIG.  12 . In so doing, the lever  65  with its two arms  62  and  63  is pivoted, as a result of which the locking slide  20  is shifted to the left in FIG. 12, so that the locking members  24  and  30  come out of engagement with the recessed portions  35  and  42 . In this position, the pin  73  projects clearly out of the outer joint portion  55 , so that it is easily recognizable from the outside that the joint or articulation  51  is in the unlocked position. The resetting of the locking slide  20  is effected in the same way as with the arrangement of FIGS. 1 to  7  by means of the spring  11  shown in FIG.  8 . 
     FIG. 13 shows a view taken along the line XIII—XIII, in FIG. 10 whereby this is essentially an outer view and merely a cross-section through the fastening arrangement of the cover  70  on the joint or articulation  51 . From this it can been that the screws  71  are inserted from below through the screw holes  67  and are rotated into the threaded sleeves  68  that are formed on the cover  70 . 
     The specification incorporates by reference the disclosure of German priority document 199 01 125.7 of Jan. 14, 1999. 
     The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.