You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION 
     The present invention relates generally to a fuel filler door catch for vehicles, and more particularly, to a fuel filler door catch for vehicles, which can be manipulated without applying a great force, thereby improving a durability of parts included in the fuel filler door catch. 
     BACKGROUND OF THE INVENTION 
     The fuel filler door is opened when filling fuel in a fuel tank, and a door catch is used for opening and closing the fuel filler door. The door catch is operated by a release handle, that is, a switch lever disposed within reach of a driver&#39;s seat. 
     FIG. 1 shows a conventional fuel filler door catch as well as a general fuel filler door. The fuel filler door  2  is hinged to a fuel filler housing  1  by means of a hinge  3  and a spring  4 . A hook plate  5  is installed to an opposite side portion of the fuel filler door  2  and locked to the catch mounted to the fuel filler housing  1 . 
     This door catch includes a catch housing  10 , a catch slide  12  and a coil spring  13 . The catch housing  10  is fastened to the fuel filler housing  1  by fastening members, such as bolts. The catch housing  1  accommodates a catch slide  12  and a coil spring  13 . The catch slide  12  is integrated with a cable extending in a straight line. The catch slide  12  moves rectilinearly in accordance with a manipulation by a driver, thus opening the fuel filler door. 
     However, since such a door catch is designed to integrate the catch slide  12  with the cable  7  extending in a straight line, the cable  7  must be bent in a U-shape so as to be connected to a release handle disposed within reach of a driver&#39;s seat. Thus, a conventional fuel filler door catch has a problem in that a great force must be applied to move the catch slide  12  rearward by means of the release handle for opening the door  2 . Furthermore, since the catch slide  12  is integrated with the cable  7 , the conventional fuel filler door catch has another problem in that it is difficult to repair the fuel filler door catch. In addition, since the catch housing  11  has to be fastened to the fuel filler housing  1  by additional fastening members  11 ,  11 ′, the conventional fuel filler door catch has still another problem in that it consumes labor and time during its production. 
     SUMMARY OF THE INVENTION 
     The present invention provides a fuel filler door catch for vehicles, which can be operated without applying great force, in addition to simplifying its assembly and maintenance due to a modular structure. A fuel filler door catch according to the invention includes a catch body mounted to a fuel filler housing, a rotary unit mounted on the catch body and rotating as a driver manipulates a cable, and a catch slide performing a rectilinear sliding movement as the rotary unit is operated, and released from a hook plate provided on a fuel filler door to open the fuel filler door. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a sectional view showing a conventional fuel filler door catch for vehicles; 
     FIG. 2 is an exploded perspective view of a fuel filler door catch according to the present invention; and 
     FIG. 3 is a perspective view of the fuel filler door catch of this invention, where the elements of the door catch is assembled into a single structure. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference is now made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. 
     FIG. 2 is a perspective view of the fuel filler door catch for vehicles according to the present invention. The fuel filler door catch includes a catch body  20 , a rotary unit  30  and a catch slide  40 . The catch body  20  is mounted to a support plate  28  of the fuel filler housing. The rotary unit  30  is mounted on the catch body  20  and rotates by a movement of the cable  7  connected to a release handle manipulated by a driver. The catch slide  40  performs a rectilinear sliding movement as the rotary unit  30  is operated, and is released from a hook plate  5  provided on a fuel filler door  2  to open the fuel filler door  2 . 
     The catch body  20  includes a base  21 , a seat part  21 ′, a support part  22  and a slide reception part  23 . The base  21  has a flat shape in order not to interfere with a movement of the rotary unit  30 . The seat part  21 ′ is formed on the front portion of the base  21  and provided on its end wall with a circular seat opening  21 ″ for receiving the locking tip  7 ′ of the cable  7 . The support part  22  is formed on the side portion of the base  21  and has a hollow interior for receiving and supporting the rotary unit  30  connected to the locking pin  7 ″ of the cable  7 . The slide reception part  23  is formed on the rear portion of the base  21  and receives the catch slide  40  within a channel  23 ′ having a length L. This catch slide  40  moves rectilinearly to be released from the hook plate  5  by a rotation of the rotary unit  30 . 
     The slide reception part  23  is provided on its one end with a locking shaft  26  for connecting the catch body  20  to a support plate  28  of the fuel filler housing. Three rows of helical slots  25  are formed on the outer circumferential surface of the locking shaft  26 . On the other hand, three protrusions  28 ′ are formed on the inner edge of the support plate  28 . The helical slots  25  engage with the protrusions  28 ′ to rotate therewith, thus allowing the locking shaft  26  and the support plate  28  to be easily assembled. An airtight ring  27  is disposed between the catch body  20  and the support plate  28  such that the catch body  20  is connected to the support plate  28 . 
     The rotary unit  30  includes a rotary boss  37 , a cable hook arm  31 , and an actuation arm  35 . The rotary boss  37  is disposed within the support part  22  of the catch body  20  and rotatably hinged to the support part  22  by a hinge pin  38 . The cable hook arm  31  is integrated with the rotary boss  37  and connected to the locking pin  7 ″ of the cable  7 . The actuation arm  35  is mounted to the rotary boss  37  while being spaced at an angle of 90° or more from the cable hook arm  31 , and moves the catch slide  40  received in the channel  23 ′ of the slide reception part  23 . 
     As shown in FIG. 3, the cable hook arm  31  includes a slit  32  for receiving the cable  7 , and a pin slot  33 . This pin slot  33  is formed on the top of the cable hook arm  31  above the slit  32 , and receives the locking pin  7 ″ of the cable  7 . In addition, the cable hook arm  31  is provided on its top surface with a stop slot  34  for holding an end of a biasing unit  39 . The biasing unit  39 , that is a torsion spring, is connected to the rotary boss  37 , and generates an elastic force so as to return the rotary unit  30  to its original position after the rotary unit  30  is rotated by the manipulation of the cable  7 . 
     The actuation arm  35  has a longitudinal slit for reducing its weight. The contact end  36  of the actuation arm  35  is enlarged in size to increase its contact force relative to the catch slide  40 . 
     It is preferable to dispose a bearing (not shown) between the rotary boss  37  and the hinge pin  38  for reducing a rotation resistance. 
     The catch slide  40  includes a movable block  41  and a stop rod  42 . The movable block  41  has an opening for receiving the contact end  36  of the rotary unit  30 . The stop rod  42  is integrated with the movable block  41 , and protruded out the locking shaft  26  of the slide reception part  23  of the catch body  20  such that the stop rod  42  is caught by or released from the hook plate  5 . 
     The operation of the fuel filler door according to this invention will be described in detail. 
     When the driver pulls the release handle disposed within reach of the driver&#39;s seat for opening the fuel filler door, as shown in FIG. 2, the cable  7  connected to the release handle is also pulled, and then the cable hook arm  31  of the rotary unit  30  is moved in the same direction as the moving direction of the cable  7 . 
     Therefore, when the cable hook arm  31  of the rotary unit  30  is rotated, the rotary boss  37  hinged to the support part  22  of the catch body  20  by the hinge pin  38  generates a rotation moment M, and then the actuation arm  35  integrated with the rotary boss  37  makes the catch slide  40  move in the channel  23 ′ having the length L of the slide reception part  23 . 
     At this time, the biasing unit  39  also moves by the movement of the cable hook arm  31  of the rotary unit  30  while generating a torsion stress. The torsion stress of the biasing unit  39  serves as an elastic force for returning the rotary unit  30  to the original position when the manipulation force F of the cable  7  is removed. 
     The movable block  41  of the catch slide  40  is moved from the original position “O” to the open position “O”′ along the channel  23 ′ of the length L by the actuation arm  35  of the rotary unit  30 . The stop rod  42  integrated with the movable block  41  of the catch slide  40  slidably moves in the locking shaft  26  of the slide reception part  23 , so the stop rod  42  is released from the hook plate  5  of the fuel filler door  2 , thus opening the fuel filler door  2 . 
     On the other hand, when the driver removes the force from the release handle, the torsion stress of the biasing unit  39  generated by the rotary unit  30  rotated by the cable  7  is removed. The biasing unit  39  thus supplies a reverse rotation moment to the rotary boss  37  for elastically returning the cable hook arm  31  of the rotary unit  30  to its original position. 
     Therefore, the actuation arm  35  returns to its original position, so the catch slide  40  returns from the opening position O′ to the original position O along the channel  23 ′ of the length L of the slide reception part  23 . As a result, the stop rod  42  is protruded out from the locking shaft  26  of the slide reception part  23 , and simultaneously moves to the hook plate  5  of the fuel filler door  2 , thus maintaining the fuel filler door  2  in a closed state. 
     As described above, the present invention provides a fuel filler door catch, which converts the manipulation force F applied to a cable by a driver into a rotation moment M by means of a rotary unit, and rectilinearly moves a catch slide for opening and closing a fuel filler door, thus rectilinearly moving the catch slide without applying a great force by using both a difference of the length between a cable hook arm and an actuation arm in addition to an angle between the cable hook arm and the actuation arm. The fuel filler door catch of this invention has a modular structure designed to connect the rotary unit to a cable using a locking pin of a cable and a pin slot, and to detachably mount a catch body to the support plate of a fuel filler housing with a simple manipulation, thus facilitating the maintenance thereof. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Summary:
The fuel filler door catch includes a catch body mounted to a fuel filler housing, a rotary unit mounted on the catch body and rotating as a driver manipulates a cable, and a catch slide performing a rectilinear sliding movement as the rotary unit is operated, and released from a hook plate provided on a fuel filler door to open the fuel filler door. The present invention is directed to provide a fuel filler door catch, which is operated without applying a great force, in addition to an improvement of durability and a facilitation of maintenance due to a modular structure.