Abstract:
Disclosed is a jet vane thrust vector control (JV-TVC) system. A general system has many problems in design techniques considering actual operation environments, and does not have reliability in component assembly design. The JV-TVC system improves thrust vector control and high angle of attack maneuvering performance of a missile by allowing rotational angles of jet vanes to maximum ±30°, precisely controls the thrust vector of the missile by preventing damages of components for the designated flight time of the missile, and improves precision and reliability in the assembly process by modularization.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a jet vane thrust vector control (JV-TVC) system, and more particularly to, a JV-TVC system which can obtain high angle of attack maneuvers and perform stabilized attitude control in rapid pitchover toward a target direction after launching a missile. 
   2. Description of the Background Art 
   In general, aerodynamic wings are installed on a missile to control the direction of the missile. Since a speed is low in launching the missile, it is not easy to control the direction of the missile by the aerodynamic wings. 
   There are thus demands for different means for controlling the direction of the missile in launching the missile. For this, a thrust vector control (TVC) system has been developed. 
   The missile using the JV-TVC system can not only control the direction but also be vertically launched in respect of operation. Accordingly, it is possible to omnidirectionally monitor the missile, provide a rapid pitch-over the missile after launching, and enter the missile into an optimum orbit within a short time according to the purpose of the missile. 
   The application methods of the TVC system can be achieved, in general, with liquid injection, a movable nozzle and a mechanical deflector method. 
   Among the methods, a mechanical TVC method achieving miniaturization such as jet vane, jetavator and jet tab has been widely used for the TVC system of the tactical missile. 
   A JV-TVC method that can provide 3-axis control of pitch, yaw and roll in one nozzle in missile flight has been widely used for the general TVC system. 
   Exemplary missiles using the JV-TVC system include VLASROC (USA), SEA SPARROW (USA), BARAK (Israel), MICA (France) and S-300 (Russia) et al. 
   The JV-TVC system controls a thrust vector by adjusting flame gas flow, by installing generally four jet vanes on an inside surface or at an end of a nozzle exit unit of a propulsion system and changing the angles of the jet vanes in combustion of the propulsion system. 
   In the conventional art, three jet vanes are individually installed on a nozzle, and the inner wall of the nozzle is formed in a conical shape. It is thus difficult to precisely assemble the system and control the thrust vector. 
   In addition to that the inner wall of the nozzle is formed in a conical shape, the root periphery of the jet vane adjacent to the inner wall of the nozzle does not make a right angle with a jet vane shaft. Therefore, the rotational angle of the jet vane inside the nozzle is restricted. A relatively large gap must be formed between the root periphery of the jet vane adjacent to the inner wall of the nozzle and the inner wall of the nozzle. Moreover, the gap must be precisely designed and formed according to the inside diameter of the inner wall of the nozzle and the size of the jet vane. It makes it more difficult to manufacture and assemble the system. 
   The JV-TVC system must satisfy performance requirements of a rocket or a missile. In the patent of Faupell et al., since the relatively large gap is formed between the root periphery of the jet vane and the inner wall of the nozzle and the jet vane shaft is simply supported through an axial hole formed in a straight line on an exit cone liner and an exit cone body composing the nozzle, heat of flames ejected from the nozzle is easily transmitted to a bearing for supporting the jet vane shaft to the exit cone body and an O-ring for maintaining airtightness through the clearance and a clearance between the jet vane shaft and the axial hole. Therefore, the bearing and the O-ring are damaged for a designated flight time, so that the thrust vector of the rocket or the missile cannot be precisely controlled. 
   As a result, the JV-TVC system is disadvantageous in the thermal respect because the jet vanes are directly exposed to the high temperature combustion gas. Ablation and thrust loss (3˜5%) are caused for a combustion time. Especially, design techniques such as mutual assembly between the jet vanes and the peripheral devices and hermetical sealing are required for precise and reliable control. 
   The most important factors of the JV-TVC system researches include development of anti-erosion materials, design of jet vanes having thermal and fluid dynamics properties to flame gas, and design of related component mechanism. A method for preventing thermal locking or sticking between a jet vane shaft and a housing by heat transfer in combustion and a method for hermetically sealing a fastening assembly part by flame gas are also essential. 
   The existing design mechanism of the JV-TVC system has many problems in design techniques considering actual operation environments. Especially, the existing design mechanism does not have reliability in component assembly design. 
   SUMMARY OF THE INVENTION 
   Therefore, an object of the present invention is to provide a jet vane thrust vector control (JV-TVC) system which can satisfy rotational angles of jet vanes and improve thrust vector control and high maneuvering performance of a missile. 
   Another object of the present invention is to provide a JV-TVC system which can precisely control a thrust vector of a missile by preventing damages of components for the designated flight time of the missile. 
   Yet another object of the present invention is to provide a JV-TVC system which can be precisely assembled in an assembly process by modularization. 
   As a result, the JV-TVC system can play a great role in controlling the direction of the missile and improving the high maneuvering performance. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a jet vane thrust vector control (JV-TVC) system, including: a rocket motor having a motor case with solid propellant, and a nozzle assembly unit protruded from the rear end of the motor case in a ring shape; a nozzle assembly including a nozzle body having a flange unit assembled to the case flange unit and a cylindrical unit extended from the flange unit in the backward direction, and a nozzle liner assembled to the inner circumferences of the cylindrical unit and the flange unit and extended longer than the cylindrical unit in the backward direction; a skin including a skin body having its front end inner circumference closely adhered to the outer circumference of the case flange unit, and being fixed by fastening a screw passing through a main wall to the case flange unit, and a mounting strip formed on the inner circumference of the skin body as a ring-shaped plate; an actuator assembly having an actuator body fixed to the front surface of the mounting strip of the skin, and a piston rod protruded from the actuator body in the backward direction and linearly reciprocated in the forward/backward direction; a shroud assembly having a cylindrical shroud body disposed at the rear end of the cylindrical unit of the nozzle body, a shroud liner assembled to the inner circumference of the shroud body, and a plurality of bosses protruded from the outer circumference of the shroud body; a jet vane assembly having a jet vane shaft rotationally supported by the bosses, and a jet vane assembled to the inside end of the jet vane shaft; a jet vane support unit having a bearing housing inserted into the boss unit, a bearing inserted into the bearing housing, for supporting the jet vane shaft, and a jet vane shaft support plate for supporting the outside end of the jet vane shaft; and an crank assembly engaged with the piston rod of the actuator, for rotating the jet vane shaft and the jet vane in the right/left direction. 
   The inner circumference of the front end of the shroud body is closely adhered to the outer circumference of the cylindrical unit of the nozzle assembly, and the front section of the front end of the shroud liner is closely adhered to the cylindrical unit and the inner circumference thereof is closely adhered to the outer circumference of the rear end of the nozzle liner. 
   A hooking jaw on which the outer circumference of the front end of the shroud liner is hooked is formed at the front end of the shroud body. 
   The bosses of the shroud body and the jet vane shaft support plate are fixed to the mounting strip of the skin by fixing screws passing through the actuator body and the mounting strip. 
   The jet vane is formed in a rectangular shape having inner and outer circumferences parallel to the center axis of the skin body and having a streamlined section, and a plane unit being parallel to the center axis of the skin body to correspond to the outer circumference of the jet vane and contacting the circumference on the basis of the center axis is formed in the position of the inner circumference of the shroud liner corresponding to the bosses. 
   The jet vane shaft includes a support unit supported by the bosses, a jet vane assembly unit incorporated with the inside end of the support unit, the jet vane being assembled to the jet vane assembly unit, and an engaged unit incorporated with the outside end of the support unit and engaged with the crank assembly. 
   A vane shaft fastening groove is formed on the root periphery of the jet vane, the jet vane assembly unit is extended from the end of the inner circumference of the support unit to both sides to make a right angle with the axial line of the jet vane shaft, and a vane shaft through hole is extended from the center of the inside surface thereof on the same axis as the jet vane shaft, and fastened to the vane shaft fastening groove of the jet vane. 
   A heat shield plate is inserted between the jet vane assembly unit and the jet vane. 
   An assembly groove into which the root periphery of the jet vane is inserted is formed on the assembly part of the inside surface of the heat shield plate with the jet vane to have the same streamlined section as the section of the jet vane. 
   The crank assembly includes a crank arm having its one end fixed to the engaged unit of the jet vane shaft, and a connection pin for relatively rotatably connecting the other end of the crank arm to the front end of the piston rod of the actuator. 
   The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
       FIGS. 1 and 2  are a partial vertical side view and a rear view illustrating a assembly state of a JV-TVC system module and a solid fuel propulsion system in accordance with the present invention; 
       FIGS. 3 and 4  are a vertical side view and a rear view illustrating a assembly state of a rocket motor and a nozzle assembly; 
       FIG. 5  is a vertical side view illustrating the JV-TVC system module in accordance with the present invention; 
       FIGS. 6   a  and  6   b  are a vertical side view and a rear view illustrating a skin; 
       FIGS. 7 and 8  are a vertical side view and a rear view illustrating a shroud assembly; 
       FIGS. 9 to 11  are a plane view, a vertical side view and a vertical front view illustrating a unit jet vane assembly; 
       FIG. 12  is a vertical side view illustrating a assembly state of the shroud assembly, the jet vane assembly, a jet vane support unit and an actuator piston rod; 
       FIG. 13  is a cross-sectional view taken along line X-X of  FIG. 12 ; 
       FIG. 14  is a vertical side view illustrating a assembly state of the jet vane assembly, a main bearing and a bearing housing; and 
       FIG. 15  is a vertical side view illustrating a assembly state of the main bearing and the bearing housing. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     FIGS. 1 and 2  are a partial vertical side view and a rear view illustrating a assembly state of a JV-TVC system module and a solid fuel propulsion system in accordance with the present invention. 
   Hereinafter, a front end portion of a missile is referred to as a forward or front end, a rear end portion of the missile is referred to as a backward or rear end, a center portion from a center axial line of the missile is referred to as an inside, an inside end or an inside surface, and an outer circumferential portion from the center axial line of the missile is referred to as an outside, an outside end or an outside surface. 
   In  FIGS. 1 and 2 , reference numerals  10  and  20  denote a rocket motor filled with a solid fuel propellant  13 , and a nozzle assembly assembled to the rocket motor  10 , respectively. 
   The rocket motor  10  includes a motor case  11  formed in a cylindrical shape, and a case flange unit  12  protruded from the rear end of the motor case  11  in a ring shape. 
   The nozzle assembly  20  includes a nozzle body  21 , and a nozzle liner  24  for protecting the nozzle body  21  from combustion gas. 
   In the nozzle body  21 , a cylindrical unit  22  and a flange unit  23  formed at the front end of the cylindrical unit  22  to correspond to the case flange unit  12  are incorporated. The nozzle liner  24  includes an exit liner  24   a  closely adhered to the inner circumference of the cylindrical unit  22 , a convergent liner  24   b  assembled to the front end of the exit liner  24   a  for surrounding the flange unit  23 , and a nozzle throat  24   c  of the exit liner  24   a.    
   The nozzle body  21  of the nozzle assembly  20  is made of a metal material, and the nozzle liner  24  is made of a heat-resistant ablative material. 
   The rocket motor  10  and the nozzle assembly  20  are assembled to each other, by fastening a high strength bolt  25  passing through a bolt through hole  23   a  formed on the flange unit  23  into a bolt fastening groove  12   a  formed at the rear end of the case flange unit  12 . 
   An O-ring  26  for maintaining airtightness is inserted between the inner circumference of the case flange unit  12  of rocket motor  10  and the outer circumference of the flange unit  23  of the nozzle assembly  20 . An O-ring groove  23   b  into which the O-ring  26  is inserted is formed on the flange unit  23 . 
   In  FIGS. 1 and 2 , M denotes the JV-TVC system module in accordance with the present invention. 
   The JV-TVC system module M includes a skin  30  assembled to the outer circumference of the case flange unit  12  of the rocket motor  10 , an actuator assembly  40  built in between the outer circumference of the cylindrical unit  22  of the nozzle body  21  of the nozzle assembly  20  and the inner circumference of the skin  30 , a shroud assembly  50  assembled to the inside of the rear end of the skin  30 , and disposed on the same axis as the nozzle assembly  20 , a plurality of jet vane assemblies  60  rotatably installed inside the shroud assembly  50 , a jet vane support unit  70  for rotatably supporting the jet vane assemblies  60  on the shroud assembly  50 , and a crank assembly  80  for transmitting a driving force of the actuator assembly  40  to the jet vane assemblies  60 . 
   As shown in  FIGS. 6   a  and  6   b , the skin  30  includes a skin body  31 , and a mounting strip  34  formed on the inner circumference of the skin body  31  as a ring-shaped plate. 
   As illustrated in  FIGS. 1 ,  3  and  6   a , the rocket motor  10  and the skin  30  are assembled to each other, by fastening a plurality of screws  33  passing through a plurality of screw through holes  32  formed on the main wall of the front end of the skin body  31  to a plurality of screw fastening grooves  14  formed on the outer circumference of the case flange unit  12 . The plurality of screw through holes  32  and the plurality of screw fastening grooves  14  are formed at regular intervals. The number of the screws  33  is dependent upon applied load. 
   Screw through holes  35  for fixing an actuator body  41 , screw through holes  36  for fixing the jet vane support unit  70  discussed later, and piston rod insertion holes  37  into which a piston rod  42  is inserted are formed respectively in four positions of the mounting strip  34  at an interval of 90°. There are also formed guide pin holes  38  for precisely determining the assembling position of the shroud assembly  50  and the jet vane assemblies  60  in regard to the skin  30 . 
   The actuator assembly  40  is a general linear actuator having the actuator body  41 , and the piston rod  42  protruded from the actuator body  40  in the backward direction for performing forward/backward motion. 
   The actuator body  41  is fixed to the front surface of the mounting strip  34  by fastening fixing screws  43   a  and  43   b , and the piston rod  42  is installed to be linearly reciprocated through the piston rod insertion holes  37  formed on the mounting strip  34 . 
   One piston rod  42  can be used, but preferably, a pair of piston rods  42  are installed to be linearly reciprocated in the opposite directions for stability of the operation. 
   A ring-shaped connection unit  42   a  connected to a crank arm  81  of the crank assembly  80  is formed at the front end of the piston rod  42 . 
   The fixing screw  43   a  is fastened to a screw fastening hole  55  formed on a boss  54  of the shroud assembly  50  discussed later through the actuator body  41  and the screw through hole  35 , thereby fixedly assembling the actuator assembly  40  and the shroud  50  to the front and rear sides of the mounting strip  34 . 
   As depicted in  FIGS. 1 and 7 , the shroud assembly  50  includes a conical shroud body  51  being disposed at the rear end of the cylindrical unit  22  of the nozzle assembly  20 , and having its diameter increased in the backward direction, and a shroud liner  52  assembled to the inner circumference of the shroud body  51 , and disposed at the rear end of the nozzle liner  24 . 
   The inner circumference of the front end of the shroud body  51  surrounds the rear end of the nozzle body  21 , and the inner circumference of the front end of the shroud liner  52  surrounds the outer circumference of the rear end of the nozzle liner  24 . 
   The shroud body  51  is made of a metal material, and the shroud liner  52  is made of a heat-resistant ablative material. Preferably, a silica phenolic heat shield material is used for the shroud liner  52  for insulation. 
   The inner circumference of the front end of the shroud body  51  is installed to overlap with the outer circumference of the rear end of the cylindrical unit  22  of the nozzle body  21 . 
   A hooking jaw  51   a  on which the outer circumference of the front end of the shroud liner  52  is hooked is formed at the front end of the inner circumference of the shroud body  51  in order to precisely maintain the assembling position of the shroud body  51  and the shroud liner  52 . 
   A plurality of support pin through holes  53   a  (eight) are formed on the main wall of the shroud body  51 , and a plurality of support pin fastening grooves  53   b  are formed on the main wall of the shroud liner  52  to correspond to the support pin through holes  53   a . The shroud body  51  and the shroud liner  52  are assembled to each other, by fastening tightening support pins  53   c  passing through the support pin through holes  53   a  to the support pin fastening grooves  53   b  and using an adhesive. 
   A plurality of bosses  54  are formed on the outer circumference of the shroud body  51 . In the drawings, four bosses  54  are formed to support four jet vane assemblies  60 . If three jet vane assemblies  60  are used, three bosses  54  are formed. 
   The front section of the shroud liner  52  is closely adhered to the rear section of the cylindrical unit  22  of the nozzle assembly  20 , and the inner circumference of the front end of the shroud liner  52  is closely adhered to the outer circumference of the rear end of the exit liner  24   a  of the nozzle liner  24  of the nozzle assembly  20 . 
   Each of the bosses  54  is formed in a rectangular shape having a circular bearing housing assembly space  54   a . Bearing housing assembly holes  52   a  and  52   b  engaged with the bearing housing assembly spaces  54   a  of the bosses  54  are formed on the shroud liner  52 , respectively. 
   The bearing housing assembly hole  52   a  of the shroud liner  52  has the same inside diameter as that of the bearing housing assembly space  54   a  of the boss  54 , and the bearing housing assembly hole  52   b  has a larger diameter than the bearing housing assembly space  54   a  and the bearing housing assembly hole  52   a . Therefore, a hooking jaw  52   c  is formed between the bearing housing assembly holes  52   a  and  52   b.    
   A screw fastening hole  55  for fixing the shroud assembly  50  to the skin  30 , and a screw through hole  56  for fixing a bearing housing  71  discussed later to the inside of the boss  54  are formed on the front surface of the boss  54 . 
   As described above, the fixing screws  43   a  passing through the actuator body  41  and the screw through holes  35  of the mounting strip  34  are fastened to the screw fastening holes  55  for fixing the shroud assembly  50  to the skin  30 . 
   The outer circumference of the shroud liner  52  is formed in a conical shape to correspond to the inner circumference of the shroud body  51 . A plane unit  57  being parallel to the center axis of the skin body  31  and contacting the circumference on the basis of the center axis is formed in the position of the inner circumference of the shroud liner  52  corresponding to the boss  54 . 
   Guide pins  58  are fastened to and protruded from the front surfaces of the bosses  54 , and guide pin holes  38  are formed on the mounting strip  34 , thereby precisely assembling the shroud assembly  40  and the jet vane assemblies  60  in regard to the skin  30 . 
   The jet vane assembly  60  includes a plurality of jet vane shafts  61  rotationally supported by each boss  54 , and a plurality of rectangular jet vanes  64  assembled to the inside ends of the jet vane shafts  61 . 
   The jet vane shaft  61  includes a support unit  61   a  supported by the boss  54 , a jet vane assembly unit  61   b  incorporated with the end of the inner circumference of the support unit  61   a , the jet vane  64  being assembled to the jet vane assembly unit  61   b , and an engaged unit  61   c  incorporated with the outside end of the support unit  61   a  and engaged with the crank assembly  80  discussed later. 
   The jet vane assembly unit  61   b  is extended from the end of the inner circumference of the support unit  61   a  to both sides to make a right angle with the axial line of the jet vane shaft  61 . A vane shaft through hole  62  is extended from the center of the inside surface of the jet vane assembly unit  61   b  on the same axis as the jet vane shaft  61 , and fastened to the vane shaft fastening groove  64   a  of the jet vane  64 . 
   A pair of screw through holes  63  are formed on both sides of the jet vane assembly unit  61   b.    
   The jet vane  64  is formed in a rectangular shape having inner and outer circumferences parallel to the center axis of the skin body  31  and having a streamlined section. A vane shaft fastening groove  64   a  to which the vane shaft through hole  62  is fastened, and a pair of screw fastening grooves  64   b  to which screws  65  passing through the pair of screw through holes  63  are fastened are formed on the jet vane  64 . 
   The jet vanes  64  must be made of a material having a high melting point and a high heat conduction coefficient that can maintain strength and rigidity at a high temperature to endure an ablation environment by high temperature high speed combustion gas. Also they have good mechanical properties at ultra-high temperature to support the loads by dynamic pressure. 
   Accordingly, the jet vanes  64  are made of a copper infiltrated tungsten (CIT) alloy, and preferably high temperature ceramic coated with ZrO 2  according to a plasma spray treatment after a final process. Here, the jet vanes  64  are coated with ZrO 2  to prevent thermal impacts by the combustion gas at an initial stage of operation by minimizing heat transfer. 
   A heat shield plate  66  is inserted between the jet vane assembly unit  61   b  and the jet vane  64  to minimize heat transfer through the jet vane shaft  61  and improve the fluid dynamics performance of the jet vane  64 . Preferably, the heat shield plate  66  is made of a molybdenum alloy steel, titanium zirconium molybdenum (TZM). 
   Preferably, the heat shield plate  66  is high temperature ceramic coated with ZrO 2  in the same manner as the jet vane  64 . 
   Screw through holes  66   b  corresponding to a pair of screw through holes  63   a  are formed on both sides of the heat shield plate  66 . 
   The screws  65  have excellent thermal-mechanical properties at a high temperature. Preferably, the screws  65  are made of a tantalum (Ta) material resistant to thermal impacts. 
   In order to prevent damages of the screws  65  by flame combustion gas and improve rigidity of the jet vane shafts  61 , an assembly groove  66   a  having the same streamlined section as the section of the jet vane  64  is formed on the assembly part of the inside surface of the heat shield plate  66  with the jet vane  64 , and the root periphery of the jet vane  64  is inserted into the assembly groove  66   a.    
   Preferably, each jet vane shaft  61  is designed to its respective jet vane  64  at the center of pressure of the jet vane  64  during the operation. 
   The jet vane support unit  70  includes a cylindrical bearing housing  71  inserted into the bosses  54  of the shroud assembly  50 , and a bearing  76  inserted between the jet vane shaft  61  and the bearing housing  71 . 
   Screw fastening grooves  71   a  to which fixing screws  72  passing through the screw through holes  56  formed on the bosses  54  are fastened are formed on the bearing housing  71 . In the drawings, four screw fastening grooves  71   a  are formed and four fixing screws  72  are used. 
   An O-ring  73   a  for maintaining airtightness is inserted between the inner circumferences of the bosses  54  and the outer circumference of the bearing housing  71 . An O-ring  73   b  for maintaining airtightness is inserted between the outer circumference of the jet vane shaft  61  and the inner circumference of the bearing housing  71 . 
   The bearing housing  71  is assembled to the shroud assembly  50  through a ring-shaped tightening strip  74  inserted between the inside surface of the bearing housing  71  and the outside surface of the jet vane assembly unit  61   b.    
   As illustrated in  FIGS. 1 ,  14  and  15 , the ring-shaped tightening strip  74  has an outside diameter larger than the bearing housing assembly hole  52   a  of the shroud body  51  and the bearing housing assembly hole  52   a  of the shroud liner  52 , and sufficiently small to be inserted into the bearing housing assembly hole  52   b  of the shroud liner  52 . Here, when the ring-shaped tightening strip  74  is inserted into the bearing housing assembly hole  52   b , the edges of the outer circumference of the ring-shaped tightening strip  74  are hooked on the hooking jaw  52   c.    
   Screw through holes  74   a  are formed on the ring-shaped tightening strip  74 . The ring shaped tightening strip  74  and the bearing housing  71  are tightly assembled to each other, by fastening tightening screws  75  passing through the screw through holes  74   a  into the screw fastening grooves  71   b  formed on the inside surface of the bearing housing  71 . 
   In order to more stably support the jet vane shaft  61 , the outside end of the engaged unit  61   c  of the jet vane shaft  61  is supported by the jet vane shaft support plate  77  assembled to the mounting strip  34  of the skin  30 . 
   The jet vane shaft support plate  77  is assembled to the skin  30  by fastening the screws  43   b  passing through the actuator body  41  and the screw through holes  35  of the mounting strip  34  to screw fastening grooves  77   a  formed at the front end of the jet vane shaft support plate  77 . 
   An axial hole  77   b  into which the jet vane shaft  61  is inserted is formed on the jet vane shaft support plate  77 , and a bearing  78  is inserted between the axial hole  77   b  and the jet vane shaft  61 . 
   The crank assembly  80  includes a crank arm  81  having its one end fixed to the engaged unit  61   c  of the jet vane shaft  61 , and a connection pin  84  for relatively rotationally connecting the other end of the crank arm  81  to the front end of the piston rod  42  of the actuator assembly  40 . 
   The jet vane shaft  61  and the crank arm  81  are assembled to be rotated together, by inserting the engaged unit  61   c  into an axis coupling hole  81   b  of a connection ring unit  81   a  formed at one end of the crank arm  81 , and passing a assembly pin  82  through the connection ring unit  81   a  and the engaged unit  61   c.    
   A stop ring  83  is inserted onto one side of the assembly pin  82 , for preventing separation of the assembly pin  82 . 
   The connection pin  84  is inserted into the ring-shaped connection unit  42   a  formed at the front end of the piston rod  42  and the other end of the crank arm  81 , so that the other end of the crank arm  81  and the front end of the piston rod  42  can be connected to be relatively rotated. 
   Reference numeral  79  denotes a position sensor installation unit formed at the rear end of the jet vane shaft support plate  77 , for installing a potentiometer (not shown). 
   The assembly process of the JV-TVC system in accordance with the present invention will now be described. 
   1. In a state where the front end of the shroud liner  52  is positioned to correspond to the hooking jaw  51   a  of the shroud body  51  of the shroud assembly  50 , the tightening support pins  53   c  passing through the pin through holes  53   a  of the shroud body  51  are assembled to the pin fastening grooves  53   b  of the shroud liner  52 , thereby forming the shroud assembly  50 . 
   2. When the jet vane  64  is inserted into the assembly groove  66   a  of the heat shield plate  66 , the vane shaft through hole  62  of the jet vane shaft  61  is fastened to the vane shaft fastening groove  64   a  of the jet vane  64 , and the screws  65  are fastened to the screw fastening grooves  64   b  of the jet vane  64  through the screw through holes  63   a  and  66   b  formed on the jet vane assembly unit  61   b  and the heat shield plate  66 , thereby assembling the jet vane assembly  60  in which the jet vane shaft  61 , the jet vane  64  and the heat shield plate  66  are assembled. 
   3. When the bearing housing  71  into which the bearing  76  is inserted is inserted into the bearing housing assembly space  54   a  of the boss  54 , the ring-shaped tightening strip  74  is inserted into the bearing housing assembly holes  52   a  and  52   b  of the shroud liner  52 , and the tightening screws  75  are fastened to the screw fastening grooves  71   b  of the bearing housing  71  through the screw through holes  74   a  of the ring-shaped tightening strip  74 , the ring-shaped tightening strip  74  is hooked on the hooking jaw  52   c  between the bearing housing assembly holes  52   a  and  52   b . Therefore, the shroud assembly  50  and the bearing housing  71  are firmly assembled to each other. 
   The bearing housing  71  is fixedly assembled to the bosses  54 , by fastening the fixing screws  72  passing through the screw through holes  56  of the bosses  54  to the screw fastening grooves  71   a  of the bearing housing  71 . 
   4. The support unit  61   a  of the jet vane shaft  61  to which the jet vane  62  is assembled is inserted into the bearing  76  of the bearing housing  71  assembled to the shroud assembly  50 . 
   Here, the outer circumference of the jet vane  62  and the plane unit  57  of the shroud liner  52  has a small clearance. 
   5. The engaged unit  61   c  of the jet vane shaft  61  is inserted into the shaft assembly hole  81   b  of the crank arm  81  of the crank assembly  80 , the assembly pin  82  is inserted to pass through the shaft assembly hole  81   b  and the engaged unit  61   c , and the stop ring  83  is inserted thereto. 
   6. The jet vane shaft  61  is rotatably supported by the jet vane shaft support plate  77  by positioning the bearing  78 , by inserting the end of the engaged unit  61   c  of the jet vane shaft  61  into the bearing  78  inserted into the axial hole  77   b  of the jet vane shaft support plate  77 . 
   7. The screw fastening grooves  77   a  of the jet vane shaft support plate  77  are positioned to correspond to the screw through holes  35  of the mounting strip  34  and the screw fastening holes  55  of the boss  54  are positioned to correspond to the screw through holes  36  of the mounting strip  34 , by inserting the guide pins  58  protruded from the boss  54  of the shroud assembly  50  into the guide pin holes  38  formed on the mounting strip  34  of the skin  30 . The jet vane shaft support plate  77  is assembled to the mounting strip  34  of the skin  30  by fastening the fixing screws  43   b  passing through the screw through holes  35  to the screw fastening grooves  77   a , and the shroud assembly  50  is assembled to the mounting strip  34  of the skin  30  by fastening the fixing screws  43  passing through the screw through holes  36  to the screw fastening grooves  55  of the boss  54 . 
   Here, the fixing screws  43   a  and  43   b  can be fastened to the screw fastening grooves  77   a  and  55  through the screw through holes  35  and  36  after passing through the actuator body  41  disposed at the front side of the mounting strip  34 , for assembling the actuator assembly  40  at the same time. 
   8. The ring-shaped connection unit  42   a  formed at the front end of the piston rod  42  is positioned to correspond to the connection ring unit  81   a  of the crank arm  81 , and the connection pin  84  is inserted thereto, thereby relatively rotatably connecting the crank arm  81  and the piston rod  42 . 
   Therefore, the assembly process of the JV-TVC system module M is finished. 
   9. As described above, in order to assemble the JV-TVC system module M and the rocket motor  10 , the front end of the skin  30  is inserted into the outer circumference of the case flange unit  12  of the rocket motor  10  and the flange unit  23  of the nozzle assembly  20 , and the screws  33  passing through the screw through holes  32  of the skin body  31  are fastened to the bolt fastening grooves  12   a  of the case flange unit  12 . Accordingly, the JV-TVC system module M is assembled to the rocket motor  10  and the nozzle assembly  20 . 
   The inner circumference of the front end of the shroud body  51  of the shroud assembly  50  is closely adhered to the outer circumference of the cylindrical unit  22  of the nozzle assembly  20 , and the front section of the shroud liner  52  is closely adhered to the rear section of the cylindrical unit  22  of the nozzle assembly  20 . 
   In the assembly process, in a state where the jet vane support unit  70  is assembled to the shroud assembly  50  and the jet vane assemblies  60  are assembled to the jet vane support unit  70 , in order to assemble the resulting structure and the skin  30 , the guide pins  58  protruded from the bosses  54  of the shroud assembly  50  are inserted into the guide pin holes  38  formed on the mounting strip  34  of the skin  30 , and the fixing screws  43   a  and  43   b  are fastened thereto. As a result, the shroud assembly  50  and the jet vane assemblies  60  are precisely assembled in regard to the skin  30 . 
   To easily assemble the skin  30  assembled with the shroud assembly  50  and the jet vane assemblies  60  to the rocket motor  10 , the plurality of screws  33  are fastened to the screw fastening grooves  14  of the case flange unit  12  of the rocket motor  10  through the screw through holes  32  formed on the skin body  31 . 
   After the assembly process is finished, when the actuator assembly  40  is operated, the piston rod  42  is linearly moved in the forward/backward direction, the jet vane shafts  61  connected to the front end of the piston rod  42  through the crank arm  81  are rotated in the right/left direction, and the jet vanes  64  assembled to the jet vane shafts  61  are rotated in the right/left direction, thereby controlling the thrust vector. 
   Since the root circumferences of the jet vanes  64  and the plane unit  57  of the shroud liner  52  of the shroud assembly  50  has a small clearance, the rotational angles of the jet vanes  64  are not restricted to operate thrust vector control and high angle of attack maneuvering performance of the missile. 
   In addition, the front section and the front inner circumference of the shroud liner  52  are assembled to the rear section and the rear outer circumference of the cylindrical unit  22 , respectively, forming complicated paths. Therefore, when flame gas is ejected from the rocket motor  10 , the flame gas and heat are rarely transmitted to the jet vane support unit  70  supporting the jet vane assemblies  60  and the crank assembly  80 . As a result, the thrust vector of the missile can be precisely controlled by preventing damages of the components for the designated flight time of the missile. 
   As discussed earlier, in accordance with the present invention, the JV-TVC system improves thrust vector control and high maneuvering performance of the missile by allowing the rotational angles of the jet vanes to maximum ±30°, precisely controls the thrust vector of the missile by preventing damages of the components for the designated flight time of the missile, and improves precision and reliability in the assembly process by modularization. 
   As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.