Patent Publication Number: US-2007119299-A1

Title: Engine for model

Description:
BACKGROUND OF THE INVENTION  
      1) Field of the Invention  
      The present invention relates to an engine for a model using an internal combustion engine for driving a toy.  
      2) Description of the Related Art  
      As a driving source for a remote controlled toy, an engine for model using liquid fuel is conventionally used. An engine for model of this kind has a cylinder mounted on an upper portion of a crankcase in which a piston reciprocates, and a heat sink head for dissipating heat is mounted on an upper portion of the cylinder. Generally, aportion of the cylinder where the piston reciprocates is hard-chrome plated to prevent abrasion. The present assignee discloses a technique concerning an engine for model in which a separate heat sink head portion is mounted on an upper portion in association with a recoil starter used for starting the engine (see Japanese Utility Model Registration No. 3080620 (pages 9 and 10, FIG. 1 for example)).  
      According to the conventional engine for model, the heat sink head for dissipating heat is mounted on the upper portion of the cylinder as a separate member, and the portion of the cylinder where the piston reciprocates is hard-chrome plated and thus, the number of parts is increased, it takes time for assembling operation, and cost is increased as a whole.  
     SUMMARY OF THE INVENTION  
      The present invention has been accomplished in view of the above circumstances, and it is an object of the invention to provide an engine for model in which the number of parts can be reduced, the engine can be manufactured easily, the engine can be assembled for a short time, and the engine can be manufactured inexpensively.  
      To achieve the above object, a first aspect of the invention provides an engine for model in which a crankshaft is rotatably disposed in a crankcase, a piston is fitted in a cylinder body such that the piston can reciprocate, the cylinder body is mounted on an upper portion of the crankcase, the piston is connected to the crankshaft through a con-rod, wherein the cylinder body is integrally formed with a cylinder portion into which the piston is fitted such that the piston can reciprocate, and a heat sink head portion formed in an upper cylinder portion. It is possible to reduce the number of parts, to manufacture the engine easily, and to assemble the engine for a short time, and to produce the engine inexpensively.  
      According to a second aspect of the invention, the cylinder body is formed with a cast of aluminum alloy having much silicon content. A surface of the cylinder body where the piston reciprocates can be prevented from being worn.  
      According to a third aspect of the invention, a surface of the piston is subjected to a surface processing of nickel-mixed plating. It is possible to prevent the surface of the piston from being worn.  
      An engine for model in which a crankshaft is rotatably disposed in a crankcase, a piston is fitted in a cylinder body such that the piston can reciprocate, the cylinder body is mounted on an upper portion of the crankcase, the piston is connected to the crankshaft through a con-rod, wherein the cylinder body is integrally formed with a cylinder portion into which the piston is fitted such that the piston can reciprocate, and a heat sink head portion formed in an upper cylinder portion. It is possible to reduce the number of parts, to manufacture the engine easily, and to assemble the engine for a short time, and to produce the engine inexpensively. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded perspective view of an engine for model according to an embodiment of the invention;  
       FIG. 2  is an exploded perspective view of a starter portion mounted on the engine for model according to the embodiment of the invention; and  
       FIG. 3  is a sectional view according to the engine for model and the starter portion of the embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENS  
      An illustrated embodiment of the present invention will be explained concretely below. FIGS.  1  to  3  are diagrams used for explaining an engine for model according to the embodiment of the invention.  FIG. 1  is an exploded perspective view of an engine for model,  FIG. 2  is an exploded perspective view of a starter portion mounted on the engine for model, and  FIG. 3  is a sectional view of the engine for model and the starter portion.  
      In these drawings, the engine for model  1  of the embodiment includes a crankcase  10 , a crankshaft  20  which is rotatably disposed in the crankcase  10 , a piston  30  connected to the crankshaft  20  through a con-rod  34 , and a cylinder body  40  in which the piston  30  is fitted such that the piston  30  can reciprocate therein and which is mounted on an upper portion of the crankcase  10 . A starter  50  is mounted on the crankcase  10 . The starter  50  rotates the crankshaft  20  when the engine is started.  
      The crankcase  10  is a case of aluminum alloy or the like. A shaft hole is formed in the crankcase  10  so that the crankshaft  20  is rotatably disposed in the shaft hole. The crankcase  10  is formed with flange portions  11  to  13 . An upper portion of the flange portion  11  is opened such that the flange portion  11  is in communication with the shaft hole, and the cylinder body  40  is mounted on the flange portion  11 . The flange portion  12  is opened so that the starter  50  is mounted in such a manner that the starter  50  is connected to an end of the crankshaft  20 . The flange portion  13  has openings, and supply portions of liquid fuel and air are mounted on the openings such that they are in communication with the shaft hole at a location adjacent to the upper flange portion  11 . The crankshaft  20  has one end portion side formed into a slightly thin output shaft portion  21 , and the other end portion side formed into a disk-like crank plate portion  22  having a wide diameter. The crankshaft  20  is formed with a through hole  23  through which a side surface of an intermediate shaft and the crank plate  22  are brought into communication with each other. The through hole  23  is in communication with the openings of the flange portion  13  so that liquid fuel and air are supplied during rotation of the crankshaft  20 . A hole  24  is formed at a location of the crank plate  22  away from its axis. A crankpin  25  is mounted in the hole  24 .  
      The cylinder body  40  is a cast of aluminum alloy having much silicon content to enhance the abrasion resistance. The cylinder body  40  is integrally formed with the upper heat sink head portion  41  and the lower cylinder portion  42 . The piston  30  is fitted into the cylinder portion  42  such that the piston  30  can reciprocate. The heat sink head portion  41  is formed at its central portion with a hole in which a glow plug  46  for ignition is provided. A plurality of disks for dissipating heat are arranged on the heat sink head portion  41  in the vertical direction. The cylinder portion  42  is formed with a hole  49  in which the piston  30  is fitted such that the piston  30  can reciprocate therein. A lower end portion of the cylinder portion  42  is formed with a flange portion  44  and a flange portion  45 . The flange portion  44  has an opening which is in communication with the hole  49  into which the upper flange portion  11  of the crankcase  10  is provided. The flange portion  45  is provided at its side surface with an opening which is in communication with the hole  49 . A discharging portion for discharging exhaust gas in the side face is provided in the opening. The cylinder body  40  fixed in such a manner that the flange portion  44  abuts against the flange portion  11  of the crankcase  10  through the crankcase gasket  37 , and a bolt  47  is inserted into a hole from the side face formed in the cylinder body  40  from above. A bolt  48  is inserted into a hole formed in the same manner in the flange portion  45  of the side surface of the cylinder body  40  and a discharging portion is mounted.  
      The piston  30  is formed into a cylindrical shape whose lower side is opened. A hole  31  is formed in the piston  30  in a direction perpendicular to the axis of the piston  30 . The piston pin  32  is inserted into the hole  31  and is fixed by a piston pin pad  33 . The piston pin  32  is inserted into a mounting hole  35  formed in an upper end portion of the con-rod  34 , and the crankpin  25  is inserted into a mounting hole  36  formed in the other end portion of the con-rod  34 . That is, the piston  30  is connected to the crankshaft  20  through the con-rod  34 , and the reciprocating motion of the piston  30  is associated with rotation of the crankshaft  20 . The surface of the piston  30  is subjected to surface processing using nickel mixture plating for preventing abrasion between the surface of the piston  30  and the surface of the hole  49  of the cylinder body  40 . A normally used piston ring is not used.  
      The starter  50  rotates the crankshaft  20  when the engine is started. A starter shaft  51  is rotatably mounted on a back plate  53 . A starter shaft adapter  54  is mounted on the starter shaft  51 . The starter shaft  51  is disposed such that its one end portion side is opposed to the crank plate  22  of the crankshaft  20 , and the starter shaft  51  is connected to the crank plate  22  through the crankpin  25 . The other end portion side of the starter shaft  51  is formed in the thin shaft portion. A shaft of the crankshaft  20  rotatably mounted on the back plate  53 , and the back plate  53  is mounted on a starter mounting flange portion  12  of the crankcase  10  by a bolt  56  through an O-ring  52 . The starter shaft adapter  54  is formed into a cylindrical shape having a retaining portion which gives a rotation force from outside when the engine is started. The starter shaft adapter  54  is mounted on an shaft end side of the starter shaft  51  by a set shaft  55 .  
      According to the engine for model  1  having the above structure, like a normal engine, if a rotation force is given from outside by the starter shaft  51  of the starter  50  when the engine is started, the crankshaft  20  rotates and with this, the piston  30  reciprocates in the cylinder portion  42  of the cylinder body  40  through the con-rod  34 , a mixture gas of liquid fuel and air supplied from the fuel supply portion side into the cylinder portion  42  is compressed, the mixture gas is ignited by the glow plug  46  and the engine is started. In this embodiment, the cylinder body  40  is integrally formed with the upper heat sink head portion  41  and the lower cylinder portion  42  by casting. With this, the number of parts is reduced, the engine can be manufactured inexpensively, and it is possible to assembly the engine easily. The cylinder body  40  is a cast of aluminum alloy having much silicon content. The surface of the piston  30  is subjected to surface processing using nickel mixture plating. Therefore, it is possible to enhance the abrasion resistance, it is unnecessary to provide a separate cylinder made of different material unlike the conventional technique, and a piston ring can be omitted. Further, the hard-chrome plating of the inner surface of the cylinder can be omitted unlike the conventional technique.  
      The present invention can be utilized for an engine for model by an internal combustion engine for driving a toy.