Abstract:
The invention relates to a stop module for the swiveling motion of a rotation body ( 14 ) that is swivelably received in a housing ( 10 ). The stop module comprises a catch ( 26 ) following the trajectory of the swiveling motion on the end of the rotation body and a stop ( 48 ) comprising a damping element for delimiting the motion of the catch ( 26 ). At least one intermediate element ( 56 ) is provided between the catch ( 26 ) and the stop ( 48 ) and is supported, when impinged upon by the catch ( 26 ), on the housing ( 10 ) and on the stop ( 48 ).

Description:
This application is the national stage of PCT/EP2005/003087 filed on Mar. 23, 2005 and also claims Paris Convention priority of DE 10 2004 015 823.1 filed on Mar. 23, 2004. 
   BACKGROUND OF THE INVENTION 
   The invention concerns a stop module for delimiting the pivot motion of a rotation body which is pivotably disposed in a housing, comprising a catch on the side of the rotation body, which follows the trajectory of the pivot motion, and a stop which is provided on the housing side and comprises a damping element for delimiting the motion of the catch, wherein the stop is in the circular or circular segment-shaped trajectory of the catch. The invention also concerns a pivot unit comprising such a stop module. 
   Conventional stop modules in gripping technology are disposed e.g. between a pivot drive and a component to be pivoted, e.g. a gripping or tensioning means. The stop modules may delimit a predeterminable pivot angle, which permits exact pivoting of the rotation body or a component disposed on the rotation body to a certain position. In particular, stock absorbing elements are conventionally used as a stop, onto which the catch of the rotation body impinges. 
   A so-called impeller drive may e.g. be used as a pivot drive, wherein a cylinder is divided into two pressure chambers by an impeller, which is radially disposed in the cylinder, and with a stationary separating piece. Depending on the load exerted on one of the pressure chambers, the impeller is pivoted about the longitudinal axis of the cylinder, causing a corresponding pivot motion of a rotation body which is rotationally coupled to the impeller. The invention is clearly not limited to impeller drives but may be used for other drives, e.g. toothed rack drives. 
   DE 198 25 969 A1 discloses a means for transmitting a rotary motion from a chain guided about a chain wheel in a housing, which comprises balls which are securely interconnected by a chain chord. The chain and chain wheel thereby undergo forced guidance. The chain chord is required in the conventional device to prevent blocking of the balls on the chain wheel. The conventional device requires a relatively large amount of space due to the chain chord and the remote damping pistons. 
   U.S. Pat. No. 6,390,255 B2 discloses a rotary damper with a catch which can be moved in a viscous liquid, wherein the catch carries along a U-shaped damping valve which impinges on a spacer. 
   It has turned out that the service life of the stops or the associated shock-absorbers of the above-mentioned conventional stop modules is relatively short. It has proven to be particularly critical, when the catch impinges on the bumper at an inclined angle and not axially in the direction of the longitudinal axis of the shock absorber. The transverse forces which are thereby generated cannot be damped by the shock-absorber, thereby increasing wear of the bumper and damaging it. 
   It is the underlying purpose of the present invention to further develop a stop module in such a manner that it has a long service life and at the same time requires a small amount of space. The stops and/or bumper elements should thereby experience little wear at different adjustable pivot angles. 
   SUMMARY OF THE INVENTION 
   This object is achieved by a stop module comprising the features of the independent claim. 
   The intermediate element may thereby be supported on the housing either directly or indirectly via a component disposed on the housing. When several intermediate elements are provided, the intermediate element acting against the stop is loaded indirectly by the catch, i.e. via a further intermediate element disposed before the intermediate element. 
   By providing at least one intermediate element, the transverse forces generated upon impingement of the catch on the intermediate element facing it, are largely diverted into the housing, since the intermediate element is supported on the housing. The intermediate element only passes a force component to the stop, which is perpendicular to the abutment of the intermediate element on the housing. The main force component acting on the stop then extends in the direction of the longitudinal axis of the stop or the axis of motion of the damping element. 
   In accordance with the invention, the intermediate element or the intermediate elements are thereby freely guided in a substantially annular groove-like recess, at least largely along the trajectory of the catch. The annular groove-like recess is thereby advantageously formed by the housing or corresponding components provided in the housing. The trajectory of the catch is thereby circular or has the shape of a segment of a circle. The catch only impinges on the intermediate element facing it and preferably does not contact any further intermediate elements. This reduces the required space. 
   In accordance with the invention, the intermediate element is advantageously designed such that the forces exerted on the stop by the intermediate element are transmitted at least largely without transverse forces. Such an intermediate element advantageously has a spherical shape. A spherical shape is particularly suited for transmission or passing on of forces largely without transverse forces. 
   In a particularly preferred embodiment of the invention, several intermediate elements are provided, which are disposed one behind the other. The intermediate elements are thereby free running and not connected or chained to each other. This changes the pivot angle without changing the position of the stops. 
   The catch then only impinges on the intermediate element facing the catch. This intermediate element acts against a further intermediate element which, in turn, may act against a further intermediate element. The intermediate element facing the stop transmits the remaining force components, which have not been diverted into the housing by the other intermediate elements, to the stop largely without transverse forces. 
   In a further development of the invention, the intermediate element(s) is/are guided directly before the stop on a path extending tangentially to the trajectory of the catch and in axial extension of the stop. This prevents the intermediate element, which impinges on the stop, from transferring transverse forces to the stop. The stop or the damping element of the stop are therefore subjected to axial loads only. 
   In a further advantageous embodiment of the invention, the housing is designed such that the number of intermediate elements can be changed to adjust the pivot angle. The stops for introducing further free running intermediate elements or removing individual intermediate elements provided in the housing may thereby be detachable. Towards this end, the housing has e.g. openings in which the stops are disposed. When the stops have been removed, the intermediate elements can be inserted into or removed from the openings. 
   The stop or, when several stops are provided, all stops may be disposed on the housing to be axially adjustable for fine adjustment of the pivot angles. The stops may be screwed into the housing at different depths to change the position of the stop relative to the catch. 
   A total of two stops are advantageously provided in the trajectory of the catch to delimit the pivot motion of the catch in both directions of motion. The two stops may e.g. subtend an angle of 180° or more on the circular trajectory. The respective pivot angle may then be roughly adjusted in dependence on the number of intermediate elements in the trajectory and can be finely adjusted through insertion and fixing the stops in the housing at different depths. 
   In accordance with the invention, the stop advantageously comprises a fixed stop and a damper, wherein the damper damps the motion of the catch before the catch impinges on the fixed stop. It is thereby advantageous for the damper to be made from elastically resilient plastic material, in particular elastomeric material. The fixed stop may thereby surround the damper like a sleeve, wherein the damper projects axially past the fixed stop in the unloaded state. When the intermediate element impinges on the stop, the damper is consequently initially elastically axially compressed until the intermediate element impinges on the fixed stop, which surrounds the damper like a sleeve. A cylinder piston damper may clearly This provides a relatively large support surface of the intermediate element on the fixed stop to prevent tension peaks in the fixed stop and in the intermediate element. The service life of the stop and the intermediate elements is thereby increased. 
   The above-mentioned object is also achieved by a pivot unit comprising an inventive stop module. 

   
     Further details and advantageous embodiments of the invention can be extracted from the following description which describes and explains the invention in more detail with reference to the embodiments shown in the drawing. 
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  shows a longitudinal section through an inventive stop module; 
       FIG. 2  shows a perspective lower view of the housing of the stop module in accordance with  FIG. 1 ; 
       FIG. 3  shows insertion components for the housing in accordance with  FIG. 2 ; 
       FIG. 4   a  shows a cross-section along line IV-IV in accordance with  FIG. 1  of a first inventive embodiment; 
       FIG. 4   b  shows a cross-section along line IV-IV in accordance with  FIG. 1  of a second inventive embodiment; and 
       FIG. 5  shows an enlarged section of  FIG. 4   a.    
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows an inventive stop module  8  with a housing  10 , which has a central opening  12 . A rotation body  14  is disposed in the central opening  12  and can be pivoted relative to the housing  10 . Pivotable components, such as e.g. grippers, may be disposed on the rotation body  14 . 
   A pivot drive  16  in the form of an impeller drive is shown on the lower side of the housing  10 . The pivot drive  16  comprises a two-part housing  18  which accommodates a pneumatically loadable pivot impeller  20 . The pivot impeller  20  may be loaded on either side by compressed air, thereby pivoting the pivot impeller  20  about the axis  22 . The pivot impeller  20  has a pivot shaft  24  on its side facing the stop module  8 , which is rotationally coupled to the rotation body  14 . Pivoting of the pivot shaft  24  consequently also pivots the rotation body  14 . 
   The pivot motion of the rotation body  14  is delimited by a catch  26  provided on the rotation body  14 , which can move between two stops on the housing side. The stops are designated with reference numerals  48  and  50  in  FIGS. 4   a  and  4   b . The catch  26  projects into an annular recess  32  on the housing side. The recess  32  is formed by the housing  10  and also by two components  34 ,  36  which are shown in a perspective view in  FIG. 3 . 
   The circular disk-shaped component  36  has an annular groove  38  which is joined in its extension by a straight groove  40  adjoining the component  36  in a tangential direction. 
   The two components  36 ,  38  are received on the lower side ( FIG. 2 ) of the housing  10  in the assembled state. The housing  10  has a collar-like web  42  in the region of the central opening  12 , onto which the open side of the annular groove  38  of the component  36  is disposed. The component  34  is correspondingly inserted, such that the grooves  40  are disposed in the extension of the grooves  38 . In the extension of the grooves  40 , the housing  10  has two parallel openings  44 ,  46 , which can be accessed from the outer side of the housing and receive the stops  48 ,  50 . 
   The section of  FIGS. 4   a  and  4   b  is selected to be in the region of the annular groove  38 , the grooves  40 , and the openings  44 ,  46 . 
   In the embodiment of  FIG. 4   a , the stops  48 ,  50 , which are screwed into the openings  44 ,  46 , have a sleeve-like fixed stop  52  and a damper  54  of elastomeric material surrounded by the fixed stop  52 . The damper  54  projects past the solid stop  52  in the unloaded state. 
   The sectional view of  FIG. 4   a  clearly shows the axis of rotation  22  about which the pivot shaft  24  can be pivoted together with the catch  26 . The catch  26  thereby engages the recess  32  or the annular groove  38 . Free running intermediate elements which have the shape of balls  56  and are not motionally coupled, are provided between the catch  26  and the stops  48 ,  50 . 
   In the embodiment of  FIG. 4   a , four balls  56  are shown between the stop  46  and the catch  26 , and only one ball between the catch  36  and the stop  50 . The pivot angle can be roughly adjusted by the respective number of balls  56  between the stop  48 ,  50  and the catch  26 . Fine adjustment of the pivot angle is effected by screwing in the stops  48 ,  50  to different depths. 
   The individual free running balls  56  are each supported on the housing  10  or the component  38  on the housing side when loaded by the catch. 
   The motion of the catch  26  is limited by the balls  56 . When the catch  26  is pivoted in the direction of the four balls, the ball  56 . 4  facing the stop  48  impinges on the damping element  54  which is elastically deformed until the ball strikes the fixed stop  52 . 
     FIG. 4   b  shows stops  48 ,  50  which comprise a damper  54  in the form of a pretensioned piston rod  62  which can be axially displaced. The two axially displaceable piston rods  62  of the two stops  48 ,  50  are each surrounded by a fixed sleeve-like stop  52  which diverts forces into the stops  48 ,  50  upon impingement. 
   The pivot angle of the catch  26  in accordance with  FIG. 4   b  is approximately 180°. In this case, only one ball  56  is provided between the catch and the stop  48 ,  50 . 
   The pivot angle of  FIG. 4   a  is approximately 120°. Four balls  56  are provided between the catch  26  and the stop  48  and one ball is provided between the catch  26  and the stop  50 . 
   When the stops  48 ,  50  have been removed, the balls can be inserted into or removed from the openings  44 ,  46 . 
   The longitudinal axes of the fixed stops  48  and  50  extend in parallel in accordance with  FIGS. 4   a  and  4   b . When a pivot angle of more than 180° is desired, the two stops  48 ,  50  may be disposed not parallel but at an angle with respect to each other. 
     FIG. 5  shows the force flow when the catch  26  impinges on the ball  56 . 1  facing the catch  26 . The individual balls  56  each transmit forces F 1  through F 4  only perpendicularly to their respective abutment location  58  housing at abutment locations  58 . Only a tangential force F 1  through F 4  directed perpendicularly to the transverse force Q 1  through Q 4  is then transferred to the respectively next ball  56  along the trajectory  60  of the catch  26 . The damper disposed in the trajectory  60  of the catch  26  or its piston rod  62  is consequently loaded with the resulting tangential force F 4 , largely without transverse forces. The direction of the force F 4  acting on the piston rod  62  and damper  54  is thereby independent of the number of balls  56  between the damper  54  and the catch  26 . The direction of force F 4  changes only slightly with the insertion depth of the respective stop  48 ,  50 . By providing the balls  56 , the forces F acting on the stop  48 ,  50  or damper  54 ,  62  are largely free from transverse forces Q. This loads the damper  54 ,  62  in a largely axial direction. The damper  54 ,  62  is consequently largely uniformly loaded irrespective of the pivot angle to be adjusted. The pivot angle can also be changed in a simple fashion, i.e. through changing the number of balls  56  and/or changing the insertion depth of the stops  48 ,  50 .