Patent Publication Number: US-6661107-B2

Title: Engine generator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an engine generator and more particularly to an engine generator which can be used as a utility engine. 
     2. Discussion of Prior Arts 
     In general, many of engine generators have noise insulator cases in which engines and generators driven by the engines are accommodated. This type of engine generators are disclosed in Japanese Utility Model Application Laid-open No. Jitsu-Kai-Sho 61-66631 and Japanese Patent Application Laid-open No. Toku-Kai-Hei 11-200861. The noise insulation case, in general, has a rectangular box like configuration, in which the engine is mounted such that a crankshaft of the engine is directed in a longitudinal direction of the case. 
     Utility engines are used to give a rotation and torque to miscellaneous driven members, such as hydraulic pumps, compressors and the like by connecting the driven members to the crankshaft. Further, when the utility engines are used in rammers for civil engineering works, the rotation motion of the crankshaft is converted into a linear reciprocating motion of vibration mechanisms. 
     In prior arts, generally, an engine for generator differs from a utility engine in their constituting components, although both engines have a similar power, because respective fundamental constructions of engine units are different from each other. That is, in case of a utility engine, both ends of the crankshaft project from the crankcase. Further, a recoil starter is mounted on one end and a driven member such as a hydraulic pump is mounted on the other end. 
     On the other hand, in case of an engine generator having a noise insulation case wherein an engine and a generator are integrally accommodated, since the engine is longitudinally mounted in the noise insulation case in such a manner that a crankshaft of the engine directs in a longitudinal direction of the noise insulation case, generally, a muffler is disposed behind the engine, that is, on an extension line of the crankshaft and an air cleaner is disposed on the frontal side of the engine. The reason why these muffler and air cleaner are disposed on both front and rear sides of the engine is that a width size of the noise insulation case should be prevented from increasing. 
     However, when the muffler is disposed on an extension line of the crankshaft, a space around the extension line of the crankshaft are occupied by the muffler and as a result a driven member can not be connected with the crankshaft. Therefore, an engine unit for an engine generator can not be used as a utility engine. Since there is a difference between an engine generator and utility engine in the fundamental layout of the engine unit, respective engines need dedicated components. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a compact engine generator and it is another object of the present invention to provide an engine unit of the engine generator capable of being employed as a utility engine. 
     To achieve these objects, an engine generator having an engine convertible into a utility engine, comprises a noise insulation case for accommodating the engine generator, a crankshaft of the engine arranged in a widthwise direction of the noise insulation case, a one end of the crankshaft extending from the engine toward one side of the noise insulation case, an other end of the crankshaft extending from the engine toward the other side of the noise insulation case, a recoil starter provided on the one end of the crankshaft, a flywheel including the recoil starter therein and provided on the one end of the crankshaft, a generator provided on the one end of the crankshaft, an air cleaner arranged on the front side of the noise insulation case, and an muffler arranged on the rear side of the noise insulation case. That is, the crankshaft of the engine and other shafts connecting with the crankshaft, the flywheel shaft, a recoil starter shaft and a generator shaft are arranged in a widthwise direction of the noise insulation case and the air cleaner and the muffler are arranged in a longitudinal direction of the noise insulation case. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view showing an engine generator capable of being employed as a utility engine according to an embodiment of the present invention; 
     FIG. 2 is an elevational view of FIG. 1; 
     FIG. 3 is a side view of FIG. 1; 
     FIG. 4 is a rear view of FIG. 1; 
     FIG. 5 is a sectional view taken along a right side portion of FIG. 1; 
     FIG. 6 is a sectional view taken along a rear portion of FIG. 1; 
     FIG. 7 is a partially sectional view taken along a top portion of FIG. 1; 
     FIG. 8 is an enlarged sectional view of FIG. 6; 
     FIG. 9 is a front perspective view of an engine unit in a noise insulation case; 
     FIG. 10 is a front perspective view of the engine unit shown in FIG. 9 when a fuel tank is removed; 
     FIG. 11 is a front perspective view of an engine generator when an engine unit is used as a utility engine; 
     FIG. 12 is a rear perspective view of the engine unit shown in FIG. 11; and 
     FIG. 13 is a sectional view of a recoil starter. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, a noise insulation case  10  includes a front section  11 , a rear section  12 , a left and right side sections  13 ,  14 , a bottom section  15  and a top section  16 , having a rectangular parallelepiped configuration. The front section  11  is a front end of the noise insulation case  10  and the rear section  12  is a rear end thereof. The front section  11  has a recess in which a control panel  17  is provided. An engine switch  18 , an automatic throttle switch  19 , an AC output terminal  20  for outputting generated power and a DC output terminal  21  for charging batteries are provided on the control panel  17 , respectively. 
     Further, on the control panel  17 , there are provided an operation indicator  22   a  for indicating an operative generator, an oil indicator  22   b  for warning against a shortage of engine oil, an overload indicator  22   c  for indicating an overload of the engine. On the top section  16 , there is provided a stick like carrying handle  23  to be griped when a worker carries the engine generator. The carrying handle  23  extends in a longitudinal direction of the noise insulation case  10  and is connected at front and rear ends thereof with connecting sections  24 ,  24  integrally formed with the top section  16 . 
     The noise insulation case  10  comprises a first case member  10   a  and a second case member  10   b  molded by synthetic resin. The first case member  10   a  comprises a front section  11 , a part of both side sections  13 ,  14 , a part of the bottom section  15 , a part of the top section  16  and is integrally formed therewith. The second case member  10   b  comprises a rear section  12 , the rest part of both side sections  13 ,  14 , the rest part of the bottom section  15 , the rest part of the top section  16  and is integrally formed therewith. The respective case members  10   a ,  10   b  have connecting end surfaces  10   c ,  10   d  facing longitudinally so as to be longitudinally connected at those connecting end surfaces  10   c ,  10   d  with each other. 
     Referring to FIGS. 5,  6  and  7 , an opening is provided in the left and right side sections  13 ,  14  of the noise insulation case  10 , respectively and the opening extends to a part of the top section  16 . In order to open and close the left and right openings, L-shaped covers  25 ,  26  are provided detachably, respectively. As shown in FIG. 6, the L-shaped covers  25 ,  26  comprise a portion constituting a part of the top section  16  and a portion constituting a part of the side sections  13 ,  14  respectively. The L-shaped covers  25 ,  26  have a L-shaped cross section and a double wall structure constituted by inner plates  25   a ,  26   a  and outer plates  25   b ,  26   b  respectively and providing a noise insulation space between these inner and outer plates. There is provided a hook  28  for engaging with a groove formed in the top section  16  in the upper ends of the L-shaped covers  25 ,  26 . Thus, maintenances of an engine are available by removing the L-shaped covers  25 ,  26 . 
     The case member  10   a ,  10   b  are connected at the bottom section  15  with a base plate  31  fabricated by sheet metal. The base plate  31  has a rectangular shape and has a vertical section bent upward  32  on both sides thereof. Further, the base plate  31  has a fitting end  33  with a slit at front and rear edges thereof, respectively and has a fitting end  34  with a slit on left and right edges thereof, respectively. The case member  10   a ,  10   b  are interleaved at the bottom section  15  between the slits of the fitting ends  33 ,  34  and are connected with the base plate  31 . 
     On the other hand, in order to connect two case members  10   a ,  10   b  at the handle  23 , as shown in FIG. 5, an internal thread member  35  having a taped hole is formed by insert molding in a first handle part  23   b  integrally molded with the case member  10   b . Further, a through hole  36   b  having a larger diameter than the taped hole is formed in the first handle part  23   b  adjacent to and at the front of the internal thread member  35 . On the other hand, a second handle part  23   a  integrally molded with the case member  10   a  has a through hole  36   a  having the same diameter as the through hole  36   b . Further, a large diameter hole  36   c  is formed in the second handle part  23   a  on the frontal side of the through hole  36   a . Accordingly, when an external thread member  37  is inserted into the through hole  36   a  from the large diameter hole  36   c  and is screwed in the internal thread member  35 , the case member  10   a  is connected with the case member  10   b  at the boundary of the first handle part  23   b  and the second handle part  23   a , thus a stick like handle  23  is assembled by the connection of both handle parts  23   a ,  23   b.    
     Thus, since two case members  10   a ,  10   b  are longitudinally connected at the bottom section  31  with each other and also connected at the boundary of two handle parts  23   a ,  23   b  by the external thread member  37 , no screw heads can be observed from the outside of the noise insulation case  10 , this structure providing an aethetically good appearance. In case where the noise insulation case  10  is divided into two left and right parts, a larger number of screw members for tightening these parts is needed than the number of screw members in case of this method of dividing the noise insulation case  10  in the longitudinal direction. 
     As shown in FIG. 6, an engine unit  40  has an engine  43  incorporating a crankcase  41  and a cylinder  42  covered with a head cover  42   a . The engine  43  is mounted in the noise insulation case  10  in such a manner that a crankshaft  44  incorporated in the crankcase  41  directs in a widthwise direction of the noise insulation case  10 . The crankshaft  44  extends laterally approximately under the longitudinally middle portion of the handle  23 . As shown in FIG. 6, the engine  43  is mounted being biased toward the side section  13 . The crankshaft  44  is rotatably supported at one end section  44   a  thereof by a bearing  45  on a magneto side of the crankcase  41  and is rotatably supported at the other end section  44   b  thereof by a bearing  46  on the opposite side of the bearing  45 . The one end section  44   a  projects outside of the crankcase  41  and the other end section  44   b  is covered with a detachable shaft cover  47 . The engine unit  40  is mounted on the base plate  31  through a plurality of vibration isolating rubbers  48  and the base plate  31  has rubber mounts  49  underneath. 
     Referring to FIG. 8, a recoil starter  51  is mounted on the magneto side of the engine  43 . The recoil starter  51  has a recoil holder  52  integrally formed with a disc section  52   a  and a cylinder section  52   b . The disc section  52   a  is secured to the engine  43  by a plurality of bolts going through a plurality of installation holes  52   c . The one end section  44   a  of the crankshaft  44  penetrates the inside of the cylinder section  52   b  through a gap. A recoil pulley  54  is rotatably mounted on the outside of the cylinder section  52   b  and a recoil rope  53  is wound around the recoil pulley  54 . Also, a return spring  55  is provided on a recoil holder  52  to apply the spring force in a winding direction of the recoil rope  53 . Further, a rotary pin  56   a  having an engagement hook  56  is provided is rotatably mounted on the recoil pulley  54 . When the recoil pulley  54  is rotated by the recoil rope  53 , the rotary pin  56   a  rotates such that the engagement hook  56  is lifted up in an outward, radial direction by centrifugal force. 
     A flywheel  57  is mounted on a projection of the crankshaft  44 . The flywheel  57  includes a boss section  57   a  fixed to the crankshaft  44  through a key and a disc section  57   b  provided around the boss section  57   a . Further, an engagement ring section  57   c  is provided around the disc section  57   b . A protrusion section is formed on the inner periphery surface of the engagement ring section  57   c  in a radial inner direction so as to be engaged with the engagement hook  56 . Accordingly, when the recoil rope  53  is drawn out to rotate the crankshaft  44 , the engagement hook  56  is engaged with the protrusion section by centrifugal force and the crankshaft  44  is started to rotate through the flywheel  57 . A part of the recoil pulley  54  is accommodated inside of the engagement ring  57   a  of the flywheel  57  and therefore the flywheel  57  constitutes a part of the recoil starter  51 . As a result, a total width of the flywheel  57  and the recoil starter  51  can be reduced. Since the recoil starter  51  is mounted on the root of the projection section of the crankshaft  44 , the pulling force of the rope can be converted into a rotation force without giving a large bending force to the crankshaft  44 . 
     There are provided a plurality of connecting sections  59  projecting in an opposite direction to the engagement ring section  57   c  in the flywheel  57  and an outer rotor  61  of a generator  60  is mounted on the connecting sections  59  through bolts  62 . The outer rotor  61  comprises a disc section  61   a  which is connected with the connecting section  59  and a cylinder section  61   b  integrally formed with the disc section  61   a . A plurality of magnets  63  are fixed to the inner periphery surface of the cylinder section  61   b  at a specified interval in a circumferential direction. 
     A cooling fan  64  is disposed between the flywheel  57  and the outer rotor  61 . The cooling fan  64  has a disc section  64   a  including a ventilation guide hole at the center thereof and a plurality of fan blades  64   b  integrally provided on the surface of the disc section  64   a . The disc section  64   a  is interleaved between the disc section  61   a  of the outer rotor  61  and the connecting section  59  of the flywheel  57 . The disc section  64   a  is secured to the outer rotor  61  by fitting an engagement projection  65  to an engagement hole formed on the disc section  61   a.    
     The cooling fan  64  is enclosed by a fan cover  66  fixed to the engine  43 . This fan cover  66  functions as a duct for guiding air and cooling air discharged from the cooling fan  64  is guided toward the engine  43 . A generator cover  67  is secured to the fan cover  66  and has a disc section  67   b  including a lot of ventilation holes  67   a  and a cylinder section  67   c  integrally formed with the disc section  67   b . The generator cover  67  is secured to the fan cover at the cylinder section  67   c  thereof. 
     A stator  68  is disposed in the outer rotor  61  and is fixed to the generator cover  67  through a plurality of bolts  69  penetrating installation holes  68   a  of the generator cover  67 . The stator  68  is formed by piling up a lot of steel plates and a lot of slits  68   b  extending in a radial direction are formed around the outer periphery of the stator  68 . A coil  71  is wound around two adjacent slits  68   b , respectively. Further, the stator  68  has a ventilation hole  68   c  in the center thereof and also has a plurality of ventilation holes  68   d  extending in the radial direction. 
     Thus, the generator  60  is an outer rotor type multi-pole generator characterized in a small axial length. Further, since the flywheel  57  is one of components of the recoil starter  51 , the lengthwise size of the engine unit  40 , that is, the widthwise size of the engine generator can be shortened. As shown in FIG. 5, an inverter unit  70  is mounted on the bottom surface of the noise insulation case  10 . The inverter unit  70  is for controlling output of the generator  60  and for converting into alternating current having specified frequency. 
     The recoil starter  51  is located in the center of the engine generator when viewed from the front and the crankshaft  44  directs in the widthwise direction of the noise insulation case  10 . Therefore, a recoil knob  53   a  can be disposed in the center of the front section  11  of the noise insulation case  10 , as shown in FIG.  1  and FIG.  2 . Since the recoil knob  53   a  is disposed at the lower part of the control panel  17 , an operator can perform all operations, starting, stopping and the like from the front side. 
     Referring to FIG. 9, a fuel tank  72  is disposed in the noise insulation case  10 . Further, a filler inlet  72   a  of the fuel tank  72  is provided on the top section  16  and a tank cap  73  is screwed on the filler inlet  72   a . The fuel tank  72  is located at the front side of the noise insulation case  10  on the opposite side of the engine  43 . 
     An air cleaner  74  for cleaning air to be supplied to the engine  43  is disposed on the frontal side of the noise insulation case  10 . As shown in FIG. 12, the air cleaner  74  is attached to the engine  43  through an intake pipe  75  extending straight backward and a carburetor  76  is mounted on the intake pipe  75 . On the other hand, a muffler  77  is disposed on the rear side of the noise insulation case  10  and is connected with the engine  43  through an exhaust pipe  78 . An exhaust outlet  79  formed on the back side of the muffler  77  communicates with an exhaust outlet  79   a  formed on the back section  12  of the noise insulation case  10  and exhaust gas of the engine  43  is discharged from the back side of the noise insulation case  10 . Thus, since the air cleaner  74  is disposed on the frontal side of the noise insulation case  10  and the muffler  77  is disposed on the rear side, the widthwise length of the noise insulation case  10  can be reduced. 
     An ignition coil  80  built in a plug cap is attached to the cylinder  42 . When maintenance is performed on the plug cap, the air cleaner  74  and the like, the L-shaped cover  25  is displaced. Then, if it is not necessary to displace the L-shaped cover  26  on the opposite side, the L-shaped cover  26  may be a fixed type. 
     A plurality of cooling air inlets  81  is formed at the front end of the noise insulation case  10  and a plurality of cooling air outlets  82  are formed at the rear section  12 . As shown in FIG. 5, the cooling air outlets  82  is constituted by louvers slanted downward. When operated, as shown in FIG. 7, cooling air introduced from the front end of the noise insulation case  10  and an inverter unit  70  is efficiently cooled by the cooling air. A part of the cooling air is sucked into the engine  43  through the air cleaner  74 . On the other hand, the cooling air generated by the cooling fan  64  is introduced from either of the side sections  13 ,  14  of the noise insulation case  10  into a plurality of the ventilation holes  68   c ,  68   d  of the stator  68  through the ventilation holes  67   a  formed on the generator cover  67 . 
     Next, the cooling air is guided by the fan cover  66 , blowing the surrounding of the engine  43 . Further, after blowing the engine  43 , the cooling air turns its stream in the longitudinal direction towards a cooling air outlet  82  provided in the rear section  12  and cools the muffler  77 . In order to make a stable stream of the cooling air toward the muffler  77 , there is provided a partition for discriminating low temperature air from high temperature air in the noise insulation case  10 . 
     As shown in FIG. 6, since the engine  43  is mounted on the right side of the noise insulation case  10  when viewed from the front side and the generator  60 , the recoil starter  51  and the cooling fan  64  are disposed on the left side, a lateral center of gravity comes around the lateral center of the noise insulation case  10 . On the other hand, since the air cleaner  74  is disposed on the front side of the noise insulation case  10 , the muffler  77  is disposed on the rear side and the engine  43 , the generator  60  are situated in the center, a longitudinal center of gravity comes around the longitudinal center of the noise insulation case  10 . That is, the handle  23  is positioned approximately on the center of gravity of the engine generator. As a result, thus constituted engine generator has a good portability. 
     FIG. 11 is a perspective view of a utility engine modified from the engine unit  40  for the engine generator described before when viewed from the front side, FIG. 12 is a perspective view of the utility engine of FIG. 11 when viewed from the rear side, and FIG. 13 is a sectional view showing a recoil starter of the utility engine of FIG.  11 . 
     As shown in FIG. 13, the crankshaft  44  of the utility engine is longer than that of the engine generator. Both ends  44   a ,  44   b  of the crankshaft  44  project from the crankcase  41 , respectively. An engine cover  85  having similar configuration to the fan cover  66  is fixed to the engine unit  40  and a holder  87  is secured to a starter cover  86  attached to the engine cover  85 . Further, a recoil pulley  88  around which a recoil rope  53  is wound is rotatably mounted on the holder  87  and the recoil pulley  88  is connected with one end  44   a  of the crankshaft  44  through a coupling  89 . Further, a flywheel  57  is mounted on the recoil pulley  88 . 
     In case where the engine unit  40  is used as a utility engine, the noise insulation case  10  is removed. The other end  44   b  of the crankshaft  44  projects from the crankcase  41  and miscellaneous driven members such as a hydraulic pump, a compressor, a rammer and the like are connected with this projection. As shown in FIG. 13, the configuration of the recoil starter  51  differs from that of the engine generator but other major components of the engine unit  40  such as the engine  43 , air cleaner  74 , muffler  77  and the like, are identical in either case of a utility engine or an engine generator. 
     The air cleaner  74  and the muffler  77  are identical to those used in the engine generator. The air cleaner  74  is disposed on the front side and the muffler  77  is disposed on the rear side in the same manner as in case of the engine generator. Accordingly, the muffler  77  or the air cleaner  74  are not interfered with on an extension line of both ends  44   a ,  44   b  of the crankshaft  44  and the other end  44   b  of the crankshaft  44  can be connected with miscellaneous driven members. 
     In case of the engine generator according to the present invention, since the air cleaner  74  and the muffler  77  are arranged with the engine  43  between and the engine unit  40  is mounted in such a manner the crankshaft  44  is oriented in a widthwise direction of the noise insulation case  10 , the width of the engine generator can be shortened and as a result a compact engine generator can be realized. Further, the engine unit  40  can be converted into a utility engine without making a large modification. 
     While the present invention has been disclosed in terms of the preferred embodiment in order to facilitate better understanding of the invention, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments which can be embodied without departing from the principle of the invention set out in the appended claims.