Abstract:
An adjusting device for a push-pull rod ( 1 ) such as is used in motor vehicles between the gearshift lever and the tranmission. To achieve continuous length compensation, the invention uses a spring ( 4 ) to directly or indirectly effect clamping between the push-pull rod ( 1 ) and the housing of the adjusting device or a connector ( 6 ).

Description:
BACKGROUND OF THE INVENTION 
     a) Field of the Invention 
     The invention relates to an adjusting device for a push-pull rod, in particular to adjust length changes for the push-pull rod in continuous manner. 
     b) Description of Related Art 
     Such push-pull rods are used for instance in motor-vehicle transmissions to select and shift gears. In general a drive cable is connected to the push-pull rod and itself leads to a corresponding drive means, for instance a selecting or shifting lever or to the transmission. In order to adjust the length, for instance to compensate for tolerances, it is known with respect to such push-pull rods to adjust the rod&#39;s length in steps using a gear and mating gear and additional locking/unlocking elements. This design entails the drawback that adjustment can be carried out only stepwise, i.e., that intermediate positions are precluded. Another drawback of the known push-pull rods is the necessity to deliver them to the site of installation, for instance the assembly line of the automobile manufacturer, assembled to the drive cable. Thereby the drive cable is preset, and as a result most of the time the assembly-line worker must readjust to the precisely required length. Such a procedure frequently incurs substantial labor (unlocking the locking elements, adjusting, closing the locking elements). 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to create an adjusting device for a push-pull rod that overcomes the above cited drawbacks. 
     These problems are solved in the present invention by an adjusting device assembled in or at the push-pull rod and which directly or indirectly effects clamping between the push-pull rod and the adjusting-device housing or an affixation means. 
     The clamping, implemented in the invention by a spring, allows, when the spring is compressed, easy insertion of the push-pull rod to the desired depth and, upon releasing the spring, to reliably achieve secure positioning of the adjusting device on the push-pull rod. In this manner, the depth of insertion, i.e. the length adjustment of the cable of the push-pull rod, is reliably kept in the desired position. Using only one hand, the fitter is able to open the adjusting device of the invention, and the insertion of the push-pull rod is carried out with the other hand. In the proper setting, the desired length can be fixed in position by unlocking, by removing a securing means or by releasing the prestressed spring. 
     In a first embodiment, the adjusting device comprises within its housing a spring-loaded locking bush cooperating by its inside surface with a setting element affixable to the push-pull rod. In this design the locking bush clamps the setting element by spring force and as a result the setting element is irrotational. For the same reason the length of the adjusting device remains constant whether loaded tensively or compressively. 
     In a preferred embodiment, the inside surface of the locking bush and the cooperating outside surface of the setting element are each conical. The spring presses the conical locking bush against the conical outside surface of the setting element and in this manner reliably prevents said element from rotating. Once the setting element in turn keeps the push-pull rod in the desired position, for instance by screw-tightening, a change in the total length of the component by push or pull no longer is possible. The clamping effect between the locking bush and the setting element can be implemented by ordinary friction between two metal surfaces, by specially matched materials, by fluting, roughening and also for insance non-circular, for instance hexagonal, octagonal or other polygonal designs. It is clear furthermore that the cooperating parts also may be composed of plastic, ceramics or the like. 
     In a preferred embodiment, the setting element is a setting nut threaded on its inside and cooperating with a thread on the push-pull rod. The threads are made non-interlocking in order that the fitter can easily displace the push-pull rod relative to the setting nut. 
     In another embodiment, a helical screw is present in the housing with the push-pull rod passing through its inside. The clamping of the invention of the push-pull rod in the adjusting device takes place in that the inside diameter of the unstressed spring is less than the outside diameter of the push-pull rod, or in that the spring forces an element located between it and the push-pull rod on latter. The spring is bent for instance by rotation about its own axis to allow insertion of the push-pull rod. Thereby the spring enlarges its inside diameter and permits inserting the push-pull rod. When the spring is released, it again reduces its diameter and clamps the push-pull rod in position. 
     Besides the clamping effect of the helical spring, the adjusting device also may comprise one or more clamping elements fitted with ride-on bevels or rest surfaces facing the helical spring. 
     In a preferred embodiment the push-pull rod is held in place directly by the spring having the smaller inside diameter. If the rod is tensively or compressively loaded, then the spring will be pressed against the ride-on bevels of the clamping elements and as a result the particular spring coil diameter is further reduced In this manner the clamping effect of the adjusting device of the invention is increased even further. 
     A setting piece may be provided to more easily spread apart the spring, said piece being rigidly joined to the spring or to its ends and extending outward. The fitter is able to easily rotate the setting piece relative to the housing, for instance using the thumb of his hand holding said housing, and then he may insert the push-pull rod to the appropriate length. After the end of the setting procedure, the spring encloses or compresses the push-pull rod which it retains in this intended position and thereby the full drive element is kept at the desired length. 
     In a further embodiment, spring-loaded clamping elements are present in the housing and comprise conical surfaces (for instance outer surfaces) cooperating in such manner with one or two opposite, for instance inwardly conical, seats in such manner that the push-pull rod inserted in it is clamped in place directly or indirectly. In this design the spring presses conical elements into conical mating surfaces and illustratively a radial clamping force is then exerted by diameter reduction, leading to reliable affixation of the push-pull rod. The adjusting device of the invention may comprise a conical clamping element forced by a spring into a recess, or two clamping elements may be present which are forced by the spring into opposite directions and thereby into two mutually opposite conical recesses. This design offers reliable positional affixation for both tensile and compressive load. Illustratively the clamping elements may comprise a slot to reduce their diameter when being clamped and thereby exerting compression on the push-pull rod, or they may transfer the clamping effect directly or indirectly to the push-pull rod. 
     The indirect transmission takes place for instance using rollers or balls forced during shifting by the conical recesses against the push-pull rod and thereby automatically increasing clamping. 
     A securing means may be provided for easy assembly to keep the spring generating the compression in the compressed state in the unassembled state, whereby the clamping elements do not cooperate with the recesses and consequently the push-pull rod can be easily inserted. Once the push-pull rod has been moved into the desired position, the fitter need do no more than remove the securing means. As a result the spring is released and forces the clamping elements against the seats, achieving reliable setting of the push-pull rod to the desired length. The securing means may be in the form of a disposable splint discarded following assembly, or it may be an operating element remaining at the adjusting device to allow easy access to the spring for subsequent readjustments in order to compress said spring and render the push-pull rod displaceable relative to the recess. 
     The invention offers further ease of mounting by providing stops for the adjusting device at a position of axial displacement of the push-pull rod and/or means for automatically securing the push-pull rod in a set position. In one embodiment of the invention said means may comprise a spring-loaded securing sleeve which, in a first position, makes possible adjusting the push-pull rod and, when arriving in a second position, automatically implements stopping the push-pull rod by means of the spring force, the securing sleeve optionally being fitted with a control slot cooperating with a cam of the housing to affix the securing sleeve in the first position. 
     Further purposes, advantages, features and applications of the present invention are elucidated in the following description of the embodiments and in relation to the drawing. All described and/or graphically shown features per se or in arbitrary appropriate combination represent the object of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a first embodiment of an adjusting device according to the present invention as the device is being assembled. 
     FIG. 2 shows the first embodiment of FIG. 1 with the push-pull rod inserted into the insertion duct. 
     FIG. 3 shows the first embodiment of FIG. 1 with the push-pull rod being compressively loaded. 
     FIG. 4 shows the first embodiment of FIG. 1 with the push-pull rod being tensively loaded. 
     FIG. 5 shows a second embodiment of an adjusting device according to the present invention as the second embodiment is being assembled. 
     FIG. 6 shows the second embodiment of FIG. 2 with the push-pull rod inserted into the insertion duct. 
     FIG. 7 shows the second embodiment of FIG. 2 with the push-pull rod being compressively loaded. 
     FIG. 8 shows the first embodiment of FIG. 2 with the push-pull rod being tensively loaded. 
     FIG. 9 shows a third embodiment of an adjusting device according to the present invention. 
     FIG. 10 shows the third embodiment with the cam riding along the control slot. 
     FIG. 11 sows the securing sleeve set in a park position. 
     FIG. 12 shows a fourth embodiment of an adjusting device according to the present invention as the fourth embodiment is being assembled. 
     FIG. 13 shows the fourth embodiment of FIG. 12 with the push-pull rod inserted into the insertion duct. 
     FIG. 14 shows the fourth embodiment of FIG. 12 with the push-pull rod being compressively loaded. 
     FIG. 15 shows the fourth embodiment of FIG. 12 with the push-pull rod being tensively loaded. 
     FIG. 16 shows a variation of the first embodiment of FIG. 1 with a rectilinear guide pin. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, the adjusting device of the invention comprises a push-pull rod  1 , a setting nut  2 , a locking bush  3 , a spring  4 , a seat  5 , a connector  6  with clearance  7  and a cage  9 . In this and other embodiments, the connector  6  is a coupling means for an automotive transmission. Moreover, in this as well as in other embodiments, the connector  6  may be replaced by an extension means or by a further push-pull rod  1 . In this and in other embodiments, the pertinent disclosure is that the adjusting device is located at one end between the push-pull rod  1  and the connector  6  to the part to be driven, in this case for instance directly in front of the connection to an automotive transmission. 
     The connector  6  fitted with the clearance  7  continues in a seat  5  illustratively integral with the connector  6 . A threaded connection between the seat  5  and the connector  6  is equally applicable. A setting nut  2  is present in the seat  5  and in this instance is inserted into the cage  9  and is kept in place against axial displacement inside the seat  5 . An insertion duct  8  for the push-pull rod  1  runs through the seat  5  and through the setting nut  2 . The setting nut  2  comprises a conical outer surface cooperating by means of the locking bush  3  with a conical inside surface corresponding to the outside surface of the setting nut  2 . The locking bush  3  is kept in the locked position with the setting nut  2  by a compression spring  4  resting against a collar of the seat  5 . Upon inserting the push-pull rod  1  into the duct  8 , that is when the push-pull rod  1  shall be moved into the desired position relative to the connector  6 , the locking bush  3  will be displaced toward the connector  6  against the force of the spring  4 . The setting nut  2  is released thereby. In this design the thread configuration of push-pull rod  1  and setting nut  2  is non-interlocking and while the setting nut  2  is being rotated, the push-pull rod  1  can be inserted inside the seat  5  or held by the cage  9  as schematically shown in FIG.  2 . 
     Accordingly the fitter moves the locking bush  3  against the spring force and thereby the setting nut  2  is now freely rotatable. Next the fitter forces the push-pull rod  1  inward to the desired extent and lets go of the locking bush  3 . The spring  4  moves the conical inside surface of the locking bush  3  over the conical outside surface of the setting nut  2  and thereby precludes the setting nut  2  from rotating. A change in insertion depth of the push-pull rod  1  is implemented in this manner in the adjusting device. 
     Illustratively the thread configuration relating to the pull rod  1  and to the inside borehole of the setting nut  2  may be a multiple thread. 
     To prevent rotation of the push-pull rod  1  relative to the connector  6 , rectilinear guides may be used between the pull rod  1  and the seat  5 . Such guides for instance may be in the form of a pin  2   a  passing through the push-pull rod  1  and which by its ends projecting from the push-pull rod slides inside mating longitudinal slots inside the seat  5 . Other variations of rectilinear guides, i.e. of an anti-rotation system concerning the push-pull rod  1  and the connector  6  are also feasible. 
     Once the push-pull rod  1  together with drive cable has been adjusted to the desired extent, the locking bush  3  will be forced into and kept by the spring  4  in the locked position on the setting nut  2 , so that adjustment has been completed. 
     FIG. 2 shows the adjusting device of the invention while still in the assembled state wherein the locking bush  3  is pressed against the spring  4 , as a result of which the push-pull rod  1  can be freely move to-and-fro and thus the length of the adjusting device is easily selectable. Only after the locldng bush  3  has been let go will the spring  4  move the locking bush  3  against the setting nut  2 , thereby preventing rotation of the setting nut  2  and hence relative length change between the seat  5  and the push-pull rod  1 . The design of the invention furthermore offers the advantage that optionally the push-pull rod  1  with cable drive can be delivered separately from the connector  6 , for instance to the assembly line of an automotive manufacturer. The fitter can continuously adjust the push-pull rod  1  to the desired length. 
     FIG. 3 shows the adjusting device of the invention being loaded compressively and FIG. 4 being tensively loaded, the rigid coupling of the push-pull rod  1  to adjusting device eliminating any difference. 
     A further embodiment is shown in FIGS. 5 through 8, wherein the connection means to the automotive transmission or the other means to be driven also is referenced by  6 . A tubular housing  10  is connected to the connector  6 . Two springs  11  and  12  of which the turns run in opposite directions are present in the housing  10  and between them contain a setting piece  13 . The particular inner spring ends are linked to the setting piece  13 . The particular outer spring ends are affixed to two clamping elements  14  and  15  irrotationally mounted inside the housing  10 . The setting piece  13  comprises a radially outwardly pointing lever or head (not shown in further detail) by means of which the setting piece  13  can be rotated from the outside. The inside diameters of the springs  11  and  12  in their rest positions are less than the diameter of the push-pull rod  1  to be inserted. When rotating the setting piece  13  against the force of the two springs  11  and  12 , said springs expand radially outward to allow the push-pull rod  1  being moved through the inside space of the two springs  11  and  12 . 
     As regards the delivery-state setting shown in FIG. 5, the adjusting device together with the connector  6  is therefore separate from the push-pull rod  1 . The fitter takes the adjusting device and rotates the setting piece  13  about the longitudinal axis of the housing  10 , whereby the springs  11  and  12  become wider. Said fitter then can move the push-pull rod  1  into the widened cavity to the desired depth of insertion. Once the length has been set to the desired value, the fitter lets go the setting piece  13  and the springs  11  and  12 , on account of the reduction of their inside diameters, clamp the push-pull rod  1  into the desired position. 
     FIGS. 5 through 8 further show that this design offers an additional feature allowing increasing the clamping force of tensile and compressive loading: ride-on bevels  16  for the ends of the springs  11  and  12  are present at the clamping elements  14  and  15 . 
     FIG. 7 shows the reaction of the adjusting device to compressive loading. In this case the spring  12  is pressed against the ride-on bevel  16  and thereby reduces its diameter. Consequently the clamping action of the push-pull rod  1  is increased and it is held in position even more tightly. 
     FIG. 8 shows the effect of tensile loading on the adjusting device, whereby the ride-on bevel  16  at the clamping element  14  causes the associated spring  11  to be pulled against the ride-on bevel  16  and thereby said spring&#39;s diameter is reduced to cause increased retention of the push-pull rod  1 . 
     The embodiments of FIGS. 5 through 8 furthermore comprise a securing sleeve  17  to prevent unintended rotation of the setting piece  13  when in its operational position. The other position of the securing sleeve  17  allows rotating the setting piece  13 , and therefore, when the springs  11  and  12  are widened, the push-pull rod  1  can be inserted or removed or its position may be altered. 
     FIGS. 9 through 11 show a variation of the adjusting device of FIGS. 5 through 8. In this design a compression spring  24  is inserted between the securing sleeve  17  and the annular shoulder  25  of the housing  10  of the adjusting device. A control slot  26  is present in the wall of the securing sleeve  17  and is engaged by a cam  27  radially projecting outward from the housing  10 . The control slot  26  assumes a shape such that the securing sleeve  17  can be set in a park position as shown in FIG. 10, and, by rotating the securing sleeve  17 , in a securing position as shown in FIG.  11 . If the adjusting device or the cam  27  is in the park position, the push-pull rod  1  can be arbitrarily set, the spring  24  being stressed. By axially advancing and/or rotating the securing sleeve  17 , the cam  27  moves out of the park position and, supported by the compression spring  24 , automatically moves by means of the bevel of the control slot  26  shown in FIG. 11 into the securing position wherein it is kept by the spring  24 . Thereby the push-pull rod  1  has been locked. 
     In still another variation of the invention shown in FIGS. 12 through 15, clamping is implemented by two conical clamping elements  18  pressed by a compression spring  19  mounted between the said clamping elements  18  into associated seats  20  when in the locked position. Illustratively rollers  21  are present at the conical clamping elements  18 , though balls may also be used, to effect clamping and additionally centering and compensating tolerances. Moreover clamping may be implemented using a wedge, and affixation using an angle-lever tensioning system. The conical seats  20 , the clamping elements  18  as well as the compression spring  19  are received in an outer, tubular housing  22 . At least the cage-shaped seat for the clamping element  18  opposite the connector  6  and the two clamping elements  18  themselves comprise a preferably central borehole  9  to receive the push-pull rod  1 . 
     FIG. 12 shows the delivery condition of the adjusting device separated from the push-pull rod  1 . In this condition the two clamping elements  18  are disengaged from, i.e. the do not clamp, the seats  20  by the securing means  23 . In such a condition it is possible to easily move the push-push rod  1  into the desired position in the housing  22  as shown by FIG.  13 . Thereupon the securing means  23  is removed by being pulled out and the spring  19  moves the two clamping elements  18  into the clamping position relative to the seats  20 . This condition (operational state) is shown in FIGS. 11 and 12. 
     FIG. 14 shows the adjusting device under compressive load. The left clamping element  18  is forced specially hard into the conical seat and as a result still higher clamping of the push-pull rod is implemented by the rollers  21 . 
     FIG. 15 shows the adjusting device of the invention being tensively loaded. The right-hand clamping element  18  is pressed into the associated seat  20  and by means of the rollers  21  increases clamping of the push-pull rod  1 . The securing means  23  is disposable in this design, that is, it will be pulled only once, whereupon the adjusting device keeps the desired length setting. Even though not shown, it is also feasible to use a securing means that remains at the housing  22  and when actuated later again will compress the spring  19 , as a result of which the drive means releases the push-pull rod  1  and then allows length readjustment. 
     Obviously the individual features of the above discussed embodiments may be interchanged or be kinematically reversed without thereby deviating from the concept of the invention. Illustratively FIGS. 8 through 15 show clamping elements having outer conical surfaces; it is equally feasible to use clamping elements having inner conical surfaces which then would be moved on external conical mating surfaces. The significant feature of the invention is that a spring shall always implement clamping between elements increasing or decreasing the diameter, said elements being conical or effective in some other way. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 1 
                 push-pull rod 
               
               
                   
                 2 
                 setting screw 
               
               
                   
                 3 
                 locking bush 
               
               
                   
                 4 
                 spring 
               
               
                   
                 5 
                 seat 
               
               
                   
                 6 
                 connector 
               
               
                   
                 7 
                 clearance 
               
               
                   
                 8 
                 insertion duct 
               
               
                   
                 9 
                 cage 
               
               
                   
                 10 
                 housing 
               
               
                   
                 11 
                 spring 
               
               
                   
                 12 
                 spring 
               
               
                   
                 13 
                 setting piece 
               
               
                   
                 14 
                 clamping element 
               
               
                   
                 15 
                 clamping element 
               
               
                   
                 16 
                 ride-on bevel 
               
               
                   
                 17 
                 securing sleeve 
               
               
                   
                 18 
                 clamping element 
               
               
                   
                 19 
                 spring 
               
               
                   
                 20 
                 seat 
               
               
                   
                 21 
                 roller 
               
               
                   
                 22 
                 housing 
               
               
                   
                 23 
                 securing means 
               
               
                   
                 24 
                 spring 
               
               
                   
                 25 
                 shoulder 
               
               
                   
                 26 
                 control slot 
               
               
                   
                 27 
                 cam 
               
               
                   
                 28 
                 bevel