Abstract:
( 57 ) A travel multiplying device ( 1 ) has at least one outer pipe ( 2 ), one inner pipe ( 3 ) and one intermediate pipe ( 4 ) positioned between them, which can be moved relative to each other in the longitudinal direction ( 5 ) each by a particular distance of travel ( 16 - 36 ) with at least one cut-out formed ( 11 - 17 ) between facing surfaces ( 7, 8, 9, 10 ) of each pipe ( 2, 3, 4 ), which cut-outs show different gradients ( 18, 19 ) relative to a transverse plane ( 21 ) through the pipes ( 2, 3, 4 ), and which are coupled with each other by at least one movement linking element ( 22 - 26 ) to link the movements of the pipes. By such a travel multiplying device, a small movement of one element is transformed into a magnifying movement of another element in a simply designed and reliable manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a National Phase entry of PCT Application No. PCT/EP02/10466 filed 18 Sep. 2002 which claims priority to German Application No. 201 15 469.2 filed 19 Sep. 2001 both of which are incorporated herein by reference. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention refers to a travel multiplying device whereby a small travel of one element can be transformed into a multiplied travel of another element, for example for activating valves, throttles and other devices in the field of petroleum and natural gas extraction. 
     BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS 
     The intention is based on the object to provide a travel multiplying device, whereby a small movement of one element is transformed into a magnified movement of another element in a simply designed and reliable manner. 
     This object is solved by means of a travel multiplying device with an outer pipe, an inner pipe, and an intermediate pipe between them, each of which can be moved relative to each other in the longitudinal direction by a certain length of travel, where there is at least one cutout in each pipe in surfaces facing each other, which cutouts have different gradients relative to a transverse plane through the pipes, and which are connected to each other by means of at least one movement linking element to link the movements of the pipes. 
     One of the pipes is fixed, and the other two pipes can be moved relative to the fixed pipe. In the process, one of the pipes is moved relatively slightly and the other of these pipes is moved by a greater multiple, so that a multiplication of the travel takes place. 
     The multiplication of travel is achieved in this connection by the fact that there are cutouts in the corresponding pipes, with cutouts in different pipes moving in connection with each other by means of at least one movement linking element. The movement of one pipe is thereby transformed into a corresponding movement of the other pipe by means of the linkage through the movement linking element. The different ratios of travel of the two pipes which are movable relative to the fixed pipe derives from the different gradients of the cutouts. That is, because the movement of the pipes is connected due to the movement linkage by means of cutouts and a movement linking element, the pipe with the cutout which has a greater gradient relative to the transverse plane through the pipes moved by a distance which is a multiple relative to the pipe which has the cutout with the smaller gradient. 
     With regard to the intermediate pipe, there can be appropriate cutouts formed in both the outside and the inside of the intermediate pipe to couple its movement to both the outer and the inner pipes. To simplify the design of the travel multiplying device according to the invention in this respect, the cutout in the intermediate pipe can be in the form of a slotted cutout in the wall of the intermediate pipe. By means of this slotted cutout, the movement linking element can connect the cutouts in the outer pipe and the inner pipe with each other through the slotted cutout in the intermediate pipe, thereby coupling the inner and outer pipes with each other directly. 
     For correct guidance of the movement linking element along the cutout it is sufficient in this conjunction if the cutouts in the outer and inner pipes are in the form of recessed cutouts. That is, the cutouts extend in the form of grooves, and with a depth less than the wall thickness of the respective pipes, in the corresponding surfaces thereof. 
     In this connection, it should also be regarded as advantageous if the cutout in the outer pipe is formed in its inner surface and the cutout in the inner pipe is formed in its outer surface. 
     If the cutouts in the inner and intermediate pipes have appropriate non-zero gradients, it is sufficient for guiding the movement linking element in the area of the outer pipe if the cutout of the outer pipe extends in the transverse plane, i.e. has a gradient of zero. 
     In order to be able to transform a small movement of the inner pipe into a larger movement of the intermediate pipe, the cutout in the intermediate pipe can have a greater gradient than the cutout in the inner pipe. 
     The movement linking element can be designed in various ways. A simple embodiment can be envisioned for example as having a movement linking element placed in the cutout of the outer pipe or an inner surface of the outer pipe, which reaches through the slotted cutout in the intermediate pipe as far as the cutout in the inner pipe. In this way the movement linking element would be fixed in the inner surface of the outer pipe or would be held so that it could move in the cutout of the latter. In this case, if the inner pipe is moved for example in the longitudinal direction of the pipes, the cutouts in the inner and intermediate pipes will move along the movement linking element, and because of the differing gradients of the cutouts the movement of the inner pipe will be transformed into an amplification of the movement of the intermediate pipe. 
     However, in order to reduce the friction between the various pipes as they move relative to each other, the movement linking element can be a ball which moves along at least two cutouts which face each other in different pipes. 
     Assembly of the inner or intermediate pipe without special orientation of the inner or intermediate pipe relative to the outer pipe is simple, if the cutout in the outer pipe is a ring cutout which runs around the inside of the latter. 
     In order to be able to move the inner pipe easily relative to the other pipes, there can be at least a pair of cutouts formed in the outer surface of the inner pipe, with the cutouts inclining toward each other. Thereby an axial movement of the inner pipe can be converted into a corresponding axial movement of the intermediate pipe. 
     In order to convert a screwing movement of the inner pipe relative to the outer pipe into a corresponding screwing movement of the intermediate pipe with a larger travel relative to the outer pipe, the cutouts in the outer side of the inner pipe may extend inclined in the same direction. 
     In order to synchronize in this connection the screwing movement of the inner pipe and the intermediate pipe in a manner that they are shiftable about the same angle of rotation relative to the outer pipe, at least one vertically extending cutout may be arranged between the inclined cutouts in the outer side of the inner pipe. This cutout is associated to a corresponding also vertically extending cutout or slotted cutout in the intermediate pipe so that by a corresponding movement linking element in these vertically extending cutouts the rotation of inner pipe and intermediate pipe is coupled. 
     The bearing of the inner pipe can be improved still further if, for example, two pairs of cutouts are formed in the outer surface of the inner pipe in pairs, symmetrical to the longitudinal axis of the inner pipe. In this way the inner pipe is supported and guided at least four points around its circumference. 
     It is possible for only one pair of cutouts in the inner pipe to be coordinated with corresponding slotted openings in the intermediate pipe, for example, while the other pair of cutouts in the inner pipe could be coordinated with corresponding cutouts in the inner surface of the intermediate pipe. However, in order to be able to guide the intermediate pipe also more easily and with less friction, the slotted cutouts in the intermediate pipe can also be formed in pairs corresponding to the cutouts in the inner pipe. 
     In a simple embodiment, all of the cutouts in the inner pipe and/or all of the slotted cutouts in the intermediate pipe can have their ends positioned in two transverse planes of the corresponding pipe, with the transverse planes of the inner pipe spaced at a smaller interval than the transverse planes of the intermediate pipe. 
     It is further possible that not only a travel of the inner pipe is converted into an enlarged travel by the intermediate pipe, but at the same time an enlarged or diminished angle of rotation is achieved at the intermediate pipe when rotating the inner pipe. This may for instance be implemented in that the cutouts of the inner pipe in projection towards the transverse plane have a length different to the cutouts of the intermediate pipe. It must be noted that in this case also the vertical cutouts must extend in an inclined manner to enable a relative rotation between the inner pipe and the outer pipe. 
     It is possible to have multiple movement linking elements positioned between corresponding cutouts in the inner and outer pipes and the associated slotted cutout. It is sufficient, however, if a ball is guided along the matching cutout and slotted cutout as the movement linking element. 
     If the outer pipe is the fixed element in the travel multiplying device, then to multiply the travel it is sufficient if the inner pipe and the intermediate pipe are in the form of pipe segments; that is, if their length is shorter than that of the outer pipe. 
     The movement of the inner pipe can be linked to a travel initiating element  40 . Such a travel initiating element  40  can be for example an actuator, a shaft, a lever, a rotating spindle or the like. This travel initiating element  40  is coupled with the movement of the inner pipe  3  in such a way that a corresponding movement of the travel initiating element  40  can be converted into a displacement of the inner pipe  3  relative to the outer pipe  2 . When the inner pipe  3  is thus displaced by a certain length of travel inside the outer pipe  2 , the intermediate pipe  4  is displaced relative to the outer pipe  2  by a multiple of that travel distance. In this connection the intermediate pipe  4  can be dynamically linked to an adjusting element  42 . This adjusting element  42  connects a valve, a throttle, a so-called “blowout preventer” or other adjustable parts, for example. Here a relatively small movement of the travel initiating, element  40  is transformed by the travel multiplying device in accordance with the invention into a considerably enlarged movement of the adjusting element  42 . 
     If the movement linking element is in a fixed position for example on the inside of the outer pipe, then the inner and intermediate pipes can be mounted jointly so that they can rotate relative to the outer pipe to multiply the travel. In this case the inner pipe and the intermediate pipe are coupled in such a way that they do not rotate relative to each other. When cutouts are used in all three pipes, with balls which can move along these cutouts as the movement linking elements, it is advantageous in this connection if all of the pipes are non-rotating relative to each other. This can be achieved for example by an appropriate cross section of the pipes, so that the pipes are inserted into each other with positive locking. 
     In another embodiment it is further conceivable that the inner pipe and the intermediate pipe can be rotated relative to the outer pipe and/or relative to each other. 
     The following section contains an explanation of an advantageous embodiment of the invention on the basis of the figures included in the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The figures show the following: 
         FIG. 1  is a basic illustration of a disassembled embodiment of a travel multiplying device in accordance with the invention; 
         FIG. 2  is a diagram to illustrate the interaction of cutouts in the travel multiplying device; 
         FIG. 3  is the travel multiplying device according to  FIG. 1  in an initial position; 
         FIG. 4  is the travel multiplying device according to  FIG. 1  in a medium travel position; 
         FIG. 5  is the travel multiplying device according to  FIG. 1  in the maximum travel position; 
         FIG. 6  is the travel multiplying device according to a further embodiment in an initial position analog to  FIG. 3 ; 
         FIG. 7  is the travel multiplying device according to the further embodiment in a travel position analog to  FIG. 4 ; 
         FIG. 8  is the travel multiplying device according to the further embodiment in a travel position analog to  FIG. 5 , and 
         FIG. 9  is a diagram to illustrate the interaction of cutouts in the travel multiplying device according to the further embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1  the travel multiplying device  1  in accordance with the invention is pulled apart into individual parts, with an outer pipe  2  of the travel multiplying device  1  only half shown and with its length shortened. 
     The outer pipe  2  shows on its inner surface  7  a cutout  11  in the form of a circular cutout which runs around the entire inner surface in a transverse plane  21 , see  FIG. 2 . 
     Into the outer pipe  2  one can insert an intermediate pipe segment  4 , which can extend for example past one end of the outer pipe  2 . The intermediate pipe  4  has slotted cutouts  14 - 17  in its jacket, as cutouts which couple its inner surface  9  and outer surface  10  with each other. 
     An inner pipe  3  can be inserted into the intermediate pipe  4 . In the outer surface  8  of the inner pipe there are two cutouts  12 , 13  visible; these cutouts represent a pair of cutouts running toward each other and inclined in the upward direction in  FIG. 1 . An additional pair of such cutouts is on the back side of the inner pipe  3 , which is not visible in  FIG. 1 . 
     All of the pipes  2 ,  3 ,  4  have a longitudinal axis  27 , and in their assembled state are concentric to each other. 
     As movement linking elements  22  a number of balls  23 - 26  are placed in the cutouts  11 - 17 . In this connection their placement is such that ball  23  far example is inserted into cutout  12  of the inner pipe  3  and protrudes from this cutout far enough so that it reaches through the slotted cutout  14  in the intermediate pipe  4  and engages the ring cutout  11  an the inner surface  7  of the outer pipe  2 . The same applies by analogy to the other balls  24 - 26 . 
       FIG. 2  shows a basic representation to explain the multiplication of travel by the device in accordance with the invention. 
     In particular, it shows the cutouts  11  an the inner surface  7  of the outer pipe  2 , the slotted cutouts  14  and  15  of the intermediate pipe  4 , and two cutouts  12 , 13  in the inner pipe  3 . 
     The cutout  11  lies essentially in a transverse plane  21  which runs perpendicular to the longitudinal direction  5  of the various pipes. Lower ends  29  of the cutouts  12 , 13  and of the slotted cutouts  14 , 15  lie in transverse planes  31 ,  33  which are identical with the transverse plane  21 . Upper ends  28  of the cutouts  12 - 15  lie in transverse planes  30 ,  32 . An interval  6  between the transverse planes  30 ,  31 , between which the cutouts  12 ,  13  extend, is smaller than an interval  35  between the transverse planes  32  and  33 , between which the slotted cutouts  14  and  15  extend. In the overlapping lower ends  29  of the cutouts are balls  23 ,  24 , which at the same time engage the cutout  11  of the outer pipe  2 . 
     It is also shown in particular in  FIG. 2  that the cutouts  12 , 13  are inclined at an angle  19  relative to the transverse plane  21  or  31  and converge toward each other. In equivalent manner the slotted cutouts  14 ,  15  are inclined at an angle  20  relative to the transverse plane  21  or  33 , and also converge toward each other. The respective cutouts  12 , 13  and  14 , 15  are arranged symmetrically with respect to a central axis between the cutouts; see the other figures. Additional corresponding cutouts or slotted cutouts are arranged symmetrically to the longitudinal axis  27  with respect to the cutouts shown in  FIG. 2  in the intermediate pipe  4  and the inner pipe  3 ; see for example  FIGS. 1 and 4 . 
     If the intermediate pipe  4  moves longitudinally relative to the outer pipe  2 , it can be displaced by a maximum travel distance  6 , see  FIG. 2 , in the longitudinal direction  5 . Simultaneous with the movement of the inner pipe  3 , the intermediate pipe  4  is likewise moved by the movement linkage by means of the various balls  23 - 26  in the longitudinal direction  5  relative to the outer pipe  2  by a travel distance  36 . The travel distance  36  is greater than the travel distance  6  by a multiple. It must be noted that the gradients or angles  19  for the cutouts  12 , 13  in particular are shown exaggerated in comparison to the gradient or angle  20  of the slotted cutouts  14 , 15 , so that in reality a considerably greater multiplication of travel takes place. 
     In the embodiment according to  FIG. 2  it must also be noted that the cutouts are inclined in reverse compared to the cutouts in  FIGS. 1 and 3  to  5 , so that in the exemplary implementation according to  FIG. 2  the inner pipe  3  moves in the opposite direction relative to the outer pipe  2  compared to the implementation in  FIGS. 1 and 3  to  5 . The same is true of the intermediate pipe  4 . 
       FIGS. 3 to 5  illustrate various travel positions of the intermediate pipe  4  and inner pipe  3 . 
     In  FIG. 3  the inner pipe  3  and intermediate pipe  4  are located in their starting position with travel equal to zero. At the same time the respective balls  23 - 26  are in contact with the upper ends of the corresponding cutouts, and also engage the ring cutout  11  of the outer pipe  2 . 
     In  FIG. 4  the inner pipe  3  and intermediate pipe  4  are shown in a mid-travel position. It can already be seen here that the intermediate pipe  4  is moving rapidly ahead of the inner pipe  3  in its displacement. 
       FIG. 5  shows the maximum travel position, where the respective balls  23 - 26  are in contact with the lower ends of the cutouts  12 - 17  and simultaneously engage the ring cutout  11  of the outer pipe  2 . 
     In  FIGS. 6 to 8  the travel positions are illustrated analog to  FIGS. 3 to 5  for a further embodiment of the travel multiplying device. Identical parts are in these Figures, as well as in the preceding Figures, provided by identical reference numerals. 
     The embodiment according to  FIGS. 6 to 8  differs from the previously described embodiment in particular in that the inclined extending cutouts  12 ,  13 , also see  FIG. 9 , extend inclined in the same direction on the outer side of the inner pipe  3 . This applies analogously to the inclined slotted cutouts  14 ,  15  in the intermediate pipe  4 . Vertical cutouts or slotted cutouts  38 ,  37  are provided between the inclined cutouts or slotted cutouts. 
     If the inner pipe  3  according to  FIG. 6  is turned, the ball  23  is for instance moved along the cutout  11  on the inner side of the outer pipe  2  and caused by the simultaneous engagement of this ball  23  into the cutout  12 , see  FIG. 9 , the inner pipe  3  in  FIGS. 6 to 8  in the drawing sheet plane is moved upward in a screwing movement. At the same time the intermediate pipe is also moved in the Figure plane upwards caused by the engagement of the ball  23  into the slotted cutout  14  of the intermediate pipe  4 . Caused by the different gradients of the cutouts, a multiplication of the travel in the intermediate pipe  4  in comparison to the inner pipe  3  takes place. 
       FIG. 6  shows a starting position,  FIG. 7  shows an intermediate position and  FIG. 8  shows a final position, wherein in  FIG. 8  the inner pipe and the intermediate pipe  4  are arranged at the same angle relative to the outer pipe  2  in a rotated manner. 
       FIG. 9  shows a diagram analog to  FIG. 2  for the embodiment according to  FIGS. 6 to 8 . 
     In this embodiment it also applies that for instance the slotted cutouts  14 ,  15  and  37  end in the same transverse plane  32  and are arranged with their respective other ends in the transverse plane belonging to the cutout  11  of the outer pipe. An end of the cutouts  12 ,  38  of the inner pipe is also arranged in the transverse plane of the cutout  11  and the respective other ends of these cutouts  12 ,  38  are arranged in the transverse plane  30 . The corresponding travel multiplication results from the difference intervals of the transverse planes  30 ,  32  with respect to the recess  11 . 
     In this connection it must be noted that it is possible in further embodiments that the inner pipe  3  and the intermediate pipe  4  can be rotated about different angles relative to the outer tube  2  in the travel multiplying device. This may for instance be implemented in that the lengths of the recesses  12 ,  38  in projection towards the recess  11  or the transverse plane  21  associated thereto, see  FIG. 2 , are different to the corresponding lengths of the slotted cutouts  14 ,  15 . If for instance the projected length of the recess  12  is smaller than the projected length of the slotted cutout  14 , the intermediate pipe  4  is rotated about a greater angle to the outer pipe  2  than the inner pipe between the positions of the pipes according to  FIGS. 6 and 8 . It must be noted that in this case the vertical cutout  38  must also extend in a correspondingly inclined manner. 
     It should be noted that the illustration according to the figures only shows an example of a displacement of the inner and intermediate pipes in the vertical direction. The travel multiplication device can of course be used with every possible spatial orientation of the pipes. 
     Let it also be noted that it is equally possible for example for the inner pipe  3  to have the ring cutout  11  on its outer surface  8  and to serve as a fixed pipe, relative to which the intermediate pipe  4  and the outer pipe  2  move. In this case the cutouts  12 , 13  would be on the inside  7  of the outer pipe  2 , and instead of a multiplication of travel inside the outer pipe a multiplication of travel would take place outside of the inner pipe.