Abstract:
A system of missile control surfaces includes a control surface housing, a control surface shaft which is rotatably mounted in the control surface housing, a control surface secured on the control surface shaft, a control surface drive and a coupling unit. The coupling unit couples the control surface drive to the control surface shaft in such a way that a movement of the control surface drive produces a rotation of the control surface shaft. To enable high forces to be applied reliably to a guided missile control surface, it is proposed that the coupling unit has at least one flexible tension element, which is secured on the control surface drive and is rolled up onto the control surface shaft to a certain extent.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority, under 35 U.S.C. §119, of German application DE 10 2015 005 135.0, filed Apr. 22, 2015; the prior application is herewith incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The invention relates to a system of missile control surfaces having a control surface housing, a control surface shaft, which is rotatably mounted in the control surface housing, a control surface secured on the control surface shaft, a control surface drive and a coupling unit, which couples the control surface drive to the control surface shaft in such a way that a movement of the control surface drive produces a rotation of the control surface shaft. 
         [0003]    At the nose or tail, guided missiles have control surfaces, by which their flight is guided and they thus approach a predetermined target. For movement of a missile control surface, guided missiles are fitted with a control surface drive, which introduces forces for deflection of the control surface into the control surface via a coupling unit. Owing to the high flight velocities of a guided missile, very high forces act on a control surface of the guided missile, especially during sharp steering movements. It must therefore be possible to move a control surface reliably and precisely against high opposing forces. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the present invention to indicate a system of missile control surfaces by which high forces can be applied reliably to a guided missile control surface. 
         [0005]    The object is achieved by a system of missile control surfaces of the type stated at the outset in which, according to the invention, the coupling unit has at least one flexible tension element, which is secured on the control surface drive and is rolled up onto the control surface shaft to a certain extent. It is possible for a high force to be applied reliably to the control surface by the control surface drive via the coupling unit with little backlash and little hysteresis movement. By virtue of the rolling up, simple conversion of, for example, a translational movement into a rotational movement can be produced in combination with a connection between the coupling unit and the control surface shaft which is subject at least to little backlash. 
         [0006]    The rotational movement of the control surface shaft can be achieved in both directions by a single tension element, which is guided at least substantially completely around the control surface shaft and secured at both its free ends on the control surface drive. The provision of two tension elements, each intended for a single direction of tension, is likewise possible. It is expedient if these elements are each rolled up partially onto the control surface shaft in mutually opposite directions, enabling each of the two tension elements to exert the tension on the control surface shaft in one direction. When the control surface shaft is rotated, one tension element is correspondingly rolled up on the control surface shaft and the other is unrolled from the control surface shaft. If there is only a single tension element, one end of the tension element is rolled up onto the control surface shaft and the other end is unrolled during rotation of the control surface shaft. 
         [0007]    The tension element can be a strand, a band, a flexible rack or a toothed belt or the like. It is expedient if the tension element is manufactured at least predominantly from steel, in particular as a steel band, allowing high forces to be transferred between the control surface drive and the control surface shaft. 
         [0008]    In an advantageous embodiment of the invention, the control surface drive is a translational drive having a piston unit, and the tension element is secured on the piston unit. The piston unit can be retracted and extended again into and out of a drive housing in a translational movement, with the result that the tension element can also accompany the translational movement of this retraction and extension, at least with one end. By means of a translational drive, a movement for deflection of the control surface shaft can be produced in a simple and very precise manner. It is expedient if the translational drive is a spindle drive, wherein it is expedient if the piston unit is rotation-free during its translational movement. The tension element can be screwed to the piston unit, for example, or can be secured by positive engagement, material engagement or integrally on the piston unit in some other way. 
         [0009]    It is expedient if the tension element is embodied integrally with the piston unit. It is thereby possible to achieve securing of the tension element on the piston unit in a manner which is particularly precise in terms of position. Moreover, assembly can be kept simple. For example, the tension element can be detached from the body of the piston unit on one side using the wire erosion process, while the other end of the tension element remains connected integrally to the piston unit. 
         [0010]    A particularly simple design of the coupling unit can be achieved if the coupling unit has two interengaging piston pieces, which are expediently mounted so as to be movable relative to one another. One tension element can be secured on each of the two piston pieces, or, in the case of just one tension element extending around the control surface shaft, each end of the tension element can be secured on one of said piston pieces. 
         [0011]    It is furthermore advantageous if the coupling unit has a bracing element, by which the two piston units can be braced relative to one another, e.g. by being pushed apart. The bracing element can be a threaded element which is screwed into one of the piston pieces and which pushes the other piston piece out of the first piston piece by being screwed in. 
         [0012]    Particularly in the case of rapid steering maneuvers of the guided missile, high forces can act on the control surface and hence also stress the tension element. In order to prevent the tension element being torn off an element of the control surface drive, it is advantageous if the tension element is thicker in the region in which it is secured than in the winding region, in particular radially in relation to the control surface shaft. By the thickening, it is possible to counteract a break at a fastening point, e.g. one end of a notch between the tension element and the control surface drive element embodied integrally therewith. 
         [0013]    In particular, it is advantageous if the tension element is secured on an element of the control surface drive, and a winding region of the tension element is separated from the element of the control surface drive by a gap, and, in the region of the gap, the tension element is embodied so as to thicken radially towards the end of the gap, in particular towards the control surface shaft. Thus, it is expedient if the tension element becomes thicker, in particular continuously thicker from the winding region to the end of the gap, thereby making it possible to counteract a break at the end of the gap in an effective manner. 
         [0014]    Space for the control surface mechanism in the guided missile may be severely limited, and therefore a compact design is advantageous. In this respect, it is advantageous if the control surface drive is a translational drive having a piston unit and a piston housing, and the tension element together with the piston unit extends into the piston housing. When the piston unit moves into the piston housing, one end of the tension element moves within the piston housing, and one region of the tension element moves into the piston housing. This makes it possible to arrange the winding region very close to and, in particular, partially in the piston housing. 
         [0015]    Moreover, the invention relates to a system of missile control surfaces of the type stated at the outset which can be kept particularly compact by virtue of the fact that, according to the invention, the control surface shaft is held on the control surface housing by an outer radial bearing and is held at least indirectly on the control surface housing by an inner radial bearing. It is expedient if the inner radial bearing is held on an inner housing, e.g. an engine housing or engine tube. Needle bearings are particularly suitable as bearings since they can be of particularly small construction radially and withstand high loads. 
         [0016]    It is furthermore conducive to the compactness of the system of missile control surfaces if the inner radial bearing is arranged at the axial level of the tension element. Here, the axial level refers to the axial direction of the control surface shaft. While the control surface shaft is held from the inside by the inner radial bearing, the tension element can reach at least partially around the control surface shaft from the outside. 
         [0017]    Simple assembly can be made possible if the control surface shaft is mounted on a holding unit on its side facing away from the control surface and is held axially by positive engagement on the holding unit. The positive engagement can be achieved by twisting the control surface shaft on the holding unit, for example. It is expedient if the control surface shaft and the holding unit form an axial sliding bearing. Owing to the low axial forces, this can be kept free from bodies of revolution and hence can remain of simple configuration. By way of example, the holding unit can be an engine housing or engine tube. 
         [0018]    Moreover, it is advantageous if the control surface shaft is held radially on the holding unit by an inner radial bearing. Like an axial bearing assembly, a radial bearing assembly can also be achieved in a compact way. 
         [0019]    The invention is furthermore directed to a method for assembling a system of missile control surfaces, in which a control surface drive is secured on a control surface housing. Particularly simple assembly can be achieved if a control surface shaft is inserted into the control surface housing from the outside and a flexible tension element of a coupling unit is secured on the control surface shaft. It is expedient if the tension element is secured on the control surface drive. It is advantageous if the tension element is rolled up on the control surface shaft by rotating the latter. Part of the tension element can rest externally on the control surface shaft, while another part is secured on the control surface drive. The sequence of method steps is optional and can expediently be matched to the design. 
         [0020]    Particularly simple axial retention of the control surface shaft can be achieved if it is secured axially by positive engagement on an inner axial bearing by the rotation. In particular, the control surface shaft is pushed onto a holding unit forming half of the inner axial bearing as it is inserted into the control surface housing. 
         [0021]    The above description of advantageous embodiments of the invention contains numerous features which are grouped together in a number of dependent claims. However, it may also be expedient for these features to be considered individually and grouped into other expedient combinations, especially where claims have dependency references, and therefore a single feature of a dependent claim can be combined with a single feature, several features or all the features of another dependent claim. Moreover, these features can each be combined individually and in any suitable combination both with the method according to the invention and with the device according to the invention in accordance with the independent claims. Thus, method features may also be considered in substantive terms as characteristics of the corresponding device unit, and functional device features may also be considered as corresponding method features. 
         [0022]    The above-described characteristics, features and advantages of this invention and the way in which these are achieved will be clearer and more clearly understandable in conjunction with the following description of the illustrative embodiments, which are explained in detail in conjunction with the drawings. The illustrative embodiments are used to explain the invention and do not restrict the invention to the combination of features given therein, including functional features. Moreover, features of each illustrative embodiment which are suitable for this purpose can also be considered explicitly in isolation, removed from one illustrative embodiment, introduced into another illustrative embodiment to supplement the latter and/or combined with any one of the claims. 
         [0023]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0024]    Although the invention is illustrated and described herein as embodied in a system of missile control surfaces, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0025]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0026]      FIG. 1  is a diagrammatic, perspective view of a rear portion of a guided missile having a system of missile control surfaces which contains four axially rotatable control surfaces in a case of a control surface housing opening at a rear, according to the invention; 
           [0027]      FIG. 2  is a perspective view of a control surface shaft mounted on a holding unit of an engine tube with the control surface drive situated behind the control surface shaft; 
           [0028]      FIG. 3  is a perspective view of the control surface drive from  FIG. 2  with two piston units, on each of which a tension element is secured; and 
           [0029]      FIG. 4  is a perspective view of the two piston units in the disassembled state with the two tension elements. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Referring now to the figures of the drawings in detail and first, particularly to  FIG. 1  thereof, there is shown a rear part of a guided missile  2  having a system  4  of missile control surfaces, which has four control surfaces  6 , each arranged offset by 90° relative to one another, on a control surface housing  8 . The control surfaces  6  are each secured on a control surface shaft  10 , which is inserted into the control surface housing  8  in the axial direction of its control surface  6 . The control surface shafts  10  are rotatably mounted within the control surface housing  8  in the axial direction of the control surfaces  6 , with the result that the control surfaces  6  are also rotatable, as indicated by the example of the control surface  6  shown at the top in  FIG. 1 . 
         [0031]    For each control surface  6 , a control surface drive  12  is arranged at least partially within the control surface housing  8 . The control surface drives  12  are spindle drives having a motor and a spindle, which is rotated by the motor. A control unit controls the motor in the forward or reverse direction of motion thereof, and the spindle is therefore rotated in one or the other direction. A coupling unit  14  with in each case two piston units  16 ,  18 , which are illustrated so as to be easily visible in  FIG. 3 , is screwed onto the spindle. 
         [0032]    As can be seen from  FIG. 4 , the two piston units  16 ,  18 , which are manufactured from stainless steel, are each provided with a tension element  20 ,  22 , which is in each case embodied integrally with the piston unit  16 ,  18  thereof. The tension elements  20 ,  22  are each cut out of their piston unit  16 ,  18  by a cut which produces a gap  24  and  26 , respectively, the two tension elements  20 ,  22  thus each being shaped as steel bands. The cuts have been introduced into the corresponding piston unit  16 ,  18  by wire erosion. 
         [0033]    As can be seen from  FIGS. 3 and 4 , the piston unit  16  has an inner opening  28 , into which piston unit  18  is inserted. In this arrangement, a bracing element  30  screwed into piston unit  16  serves as a stop for the piston unit  18  inserted. Tension element  22  is passed through a slot  32  in tension element  20 . 
         [0034]    The two tension elements  20 ,  22  are each provided at the end thereof with a holder formation  34  and a holding device  36 , by which they are each anchored in the control surface shaft  10 , as can be seen from  FIG. 2 . The holder formations  34  each engage in a depression in the control surface shaft  10 , and the holding device  36 , in this illustrative embodiment screws, hold the tension elements  20 ,  22  and the holder formation  34  in place. In the assembled state, the tension elements  20 ,  22  are placed around the outside of the control surface shaft  10  and rolled onto the shaft to a certain extent, as can be seen from a combination of the illustrations in  FIGS. 2 and 3 . 
         [0035]    To secure the tension elements  20 ,  22  tightly on the control surface shaft  10 , use is made of the bracing element  30 , the screwing of which into piston unit  16  pushes piston unit  18  out of piston unit  16  to a certain extent. The tension element  22  is thereby pulled through the slot  32  in tension element  20  and braced firmly against the control surface shaft  10 . 
         [0036]    During operation, the control surface drive  12  is actuated by the drive motor, causing the spindle to rotate and the piston unit  18  screwed onto the spindle to perform a translational movement  38 . As the piston unit  18  is extended from the piston housing  40 , tension element  20  exerts a tension on the control surface shaft  10 , which is arranged so as to be immobile relative to the piston housing  40  in the direction of translation. As a result, the control surface shaft  10  is rotated about its axis. As the piston unit  18  is retracted into the piston housing  40 , the tension element  22  similarly exerts a tension on the control surface shaft  10  and rotates it in the other direction. During this process, tension element  22  moves into the piston housing to a certain extent, as can be seen from the illustration in  FIG. 3 . In the illustration in  FIG. 3 , the piston unit  18  has been extended to the maximum extent out of the piston housing  40 . As it is retracted, one end of the tension element  22  is also retracted into the piston housing  40 . 
         [0037]    At the point where the tension elements  20 ,  22  are secured on the piston unit  16 ,  18  thereof, in particular at the end of the respective gap  24 ,  26 , particularly high forces occur, which could cause a tension element  20 ,  22  to tear off the corresponding piston unit  16 ,  18 . In order to avoid this, the tension elements  20 ,  22  are embodied so as to be thickened towards their end in a radial direction towards the control surface shaft  10 , as compared to the winding region of the corresponding tension element  20 ,  22 . Consequently, the radial thickness of the tension element  20 ,  22  increases in a direction towards the end of the tension element  20 ,  22  which is secured on the piston unit  16 ,  18 . As a result, the tension element  20 ,  22  is at least twice as thick at the location of the end of the gap as in the winding region, with the result that the forces arising at the end of the gap can be well absorbed by the thickness of the tension element  20 ,  22 . 
         [0038]    To assemble the system  4  of missile control surfaces, an engine tube  42 , through which the exhaust jet of an engine of the guided missile  2  is passed during the operation of the guided missile  2 , is secured on the control surface housing  8 . For each control surface shaft, the engine tube  42  has a holding unit  44 , on which an inner radial bearing  46  is mounted or has already been mounted. The control surface shaft  10  is then pushed onto the holding unit  44  through the control surface housing  8 , with the result that the control surface shaft  10  fits over the inner radial bearing  46 . The holding unit  44  has an outward-pointing formation  48  in the form of a bayonet catch, into which a corresponding mating part of the control surface shaft  10  engages. Rotating the control surface shaft  10  through 90° causes the mating part to engage behind the bayonet piece  48  of the holding unit  44 , thus forming positive engagement in the axial direction of the control surface shaft  10  and ensuring that the control surface shaft  10  is secured on the holding unit  44  in the axial direction. With the corresponding mating part of the control surface shaft  10 , the bayonet piece  48  forms an axial sliding bearing, by which the control surface shaft  10  is held on the engine tube  42  in the axial direction. The control surface shaft  10  is held in the radial direction in the control surface housing  8  by an outer radial bearing  50 , which has already been connected to the control surface shaft  10  before assembly. 
         [0039]    Both the inner radial bearing  46  and the outer radial bearing  50  are embodied by needle bearings. The use of this very advantageous and also load-bearing rolling bearing is possible since the coupling of the control surface shaft  10  to the control surface drive  12  allows very wide dimensional tolerances and does not introduce any axial forces into the control surface shaft  10 . The required axial guidance of the control surface shaft  10  is achieved by the sliding bearing surfaces. The use of a sliding bearing is possible without problems here since only relatively low axial forces occur during the use of the system  4  of control surfaces. 
         [0040]    Piston unit  16  is then introduced with its tension element  20  into the control surface housing  8  from the rear towards the front, and the control surface shaft  10  is twisted into a position such that tension element  20  can be screwed to the control surface shaft  10  by its holding device  36 , which is embodied as a screw. This can be accomplished by means of an appropriate tool through the rear opening of the control surface housing  8 , the opening being illustrated in  FIG. 1 . 
         [0041]    The control surface shaft is then rotated through about 180°, with the result that piston unit  16  is pulled into the control surface housing  8  to some extent. The control surface drive  12  with the preassembled piston unit  18  can then be pushed into the control surface housing  8  from the front, and tension element  22  is threaded through the slot  32  in tension element  20 . With the aid of the screw  36 , tension element  22  is screwed to the control surface shaft  10  at the appropriate point on the latter, as can be seen from  FIG. 2 . The bracing element  30  is then screwed into piston unit  16 , and the two tension elements  20 ,  22  are braced firmly against the control surface shaft  10 . 
         [0042]    Owing to the bracing of the steel bands, these are jointly under prestress so as to achieve backlash-free conversion of the translational movement into a rotational movement. During movement of the control surface shaft  10 , the cylindrical region of the control surface shaft rolls in the immediate vicinity of the two piston elements  16 ,  18 , as seen relative to the spindle. During this process, one of the tension elements  20 ,  22  is unrolled from the cylindrical surface, and the other tension element  22 ,  20  is correspondingly rolled up. During this process, there are no relative movements at points of contact between two bodies, and there is therefore also no friction. The material friction produced in the steel bands by the alternating bending is so small that it is negligible. 
         [0043]    The axial positive engagement between the control surface shaft  10  and the holding unit  44  has been established by rotating the control surface shaft  10  into the position in which tension element  22  can be screwed to the control surface shaft  10 . This positive engagement is maintained within the entire operating movement range of the control surface shaft  10 , thus ensuring that the control surface  6  subsequently screwed onto the control surface shaft  10  remains firmly connected to the control surface housing  8 . 
         [0044]    During the operation of the guided missile  2 , this flies towards a target and is guided towards the target by its seeker head in conjunction with its control unit. The control unit also controls the control surface drives  12  and hence a control surface movement of the control surfaces  6 . By means of the coupling unit  14  with its two tension elements  20 ,  22 , the translational movement of the control surface drive  12  or of the two piston units  16 ,  18  is converted into a rotational movement of the control surface shaft  10  and hence of the corresponding control surface  6 . 
         [0045]    This translational movement is converted from the tangential direction of the spindle of the control surface drive  12  into a circumferential direction of the control surface shaft  10  by means of the coupling on the circumference of a cylindrical surface of the control surface shaft  10 . The translational movement becomes a rotary movement. 
         [0046]    The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
     2  guided missile     4  system of missile control surfaces     6  control surface     8  control surface housing     10  control surface shaft     12  control surface drive     14  coupling unit     16  piston unit     18  piston unit     20  tension element     22  tension element     24  gap     26  gap     28  opening     30  bracing element     32  slot     34  holder formation     36  holding means     38  translational movement     40  piston housing     42  engine tube     44  holding unit     46  inner radial bearing     48  bayonet piece     50  outer radial bearing