Abstract:
Air blower apparatus ( 20 ) in which a fan boss ( 41 ) at the rotational center portion of a fan ( 29 ) has a recessed form. Meanwhile, the central part of the body portion ( 21 ) of the air blower apparatus ( 20 ), i.e., a boss portion ( 38 ), has a projecting form to be housed within the recessed fan boss ( 41 ). The central part of the body potion ( 21 ), i.e., the boss portion ( 38 ), is housed within the recessed fan boss ( 41 ) at the rotational center portion of the fan ( 29 ), and the rotary shaft ( 39 ) of the body portion ( 21 ) of the air blower apparatus ( 20 ) is mounted on the fan ( 29 ).

Description:
This application is a divisional of copending application Ser. No. 09/253,019, filed Feb. 19, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an air blower apparatus, and more particularly to an air blower apparatus that takes up less space. 
     2. Description of the Related Art 
     FIG. 8 shows the structure of an air blower apparatus  20  powered by a hydraulic motor  23 . 
     As shown in FIG. 8, a duct  15  is provided in an engine chamber, not shown. A shroud  28  is connected to the duct  15 . The body portion  21  of the air blower apparatus  20  is fixed to the inner walls of the shroud  28 . 
     A rotary shaft  39  is provided on the body portion  21  of the air blower apparatus  20 . The hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20  so as to connect with the rotary shaft  39 . Meanwhile, a fan boss  41 ′ is provided on the rotational center portion of a fan  29 . The fan boss  41 ′ is mounted on the rotary shaft  39  of the body portion  21  of the air blower apparatus  20 . As a result, the fan  29  is contained within the shroud  28 . The air blower apparatus  20  is constituted as above. 
     With the air blower apparatus  20  shown in FIG. 8, when the hydraulic motor  23  runs, the rotary shaft  29  rotates and thereby the fan  29  rotates. When the fan  29  rotates, devices, not shown, disposed within the engine chamber are blasted with air via the duct  15  and thus cooled. 
     The air blower apparatus  20  in FIG. 8 is provided within the engine chamber. Meanwhile, in addition to the air blower apparatus  20 , various devices such as a radiator, engine, and hydraulic pump driven by the engine are also provided within the engine chamber. Consequently, space for the air lower apparatus  20  is limited within the engine chamber. 
     For this reason, there is a demand for an air blower apparatus that occupies as little space as possible. In other words, there is a demand for reducing the width of the air blower apparatus  20  in the direction of the rotary shaft  39 . 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to reduce the space required by air blower apparatus by reducing the width of the air blower apparatus in the direction of its rotary shaft. 
     In order to achieve the abovementioned object, the first invention of the present invention is an air blower apparatus comprising a hydraulic motor and a body portion provided with a rotary shaft, the hydraulic motor being mounted on the rotary shaft, the rotary shaft on which the hydraulic motor is mounted being mounted on a fan, whereby the fan is rotated by driving the hydraulic motor, wherein the fan and the body portion of the air blower apparatus are disposed so as to partially overlap each other in the direction of the rotary shaft, making width of the air blower apparatus in the direction of the rotary shaft less than total of width of the body portion of the air blower apparatus in the direction of the rotary shaft and width of the fan in the direction of the rotary shaft. 
     The first invention is explained with reference to FIG.  2 . 
     With the first invention, the fan  29  and body portion  21  of the air blower apparatus  20  are disposed so as to partially overlap in the direction of the rotary shaft. The width of the air blower apparatus  20  in the direction of the rotary shaft is therefore less than the total of the width of the body portion  21  of the air blower apparatus  20  in the direction of the rotary shaft and the width W of the fan  29  in the direction of the rotary shaft. 
     With the first invention, the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small and the space occupied by the air blower apparatus  20  can be made small, because the fan  29  and body portion  21  of the air blower apparatus  20  are disposed so as to partially overlap in the direction of the rotary shaft. 
     In order to achieve the abovementioned object, the second invention of the present invention is an air blower apparatus comprising a hydraulic motor and a body portion provided with a rotary shaft, the hydraulic motor being mounted on a rotary shaft of the body portion, the rotary shaft of the body portion which the hydraulic motor is mounted on being mounted on a fan, and the fan being rotated by driving the hydraulic motor, wherein a rotational center portion of the fan is formed with a recess; and a substantially central portion of the body portion of the air blower apparatus is formed into a projection to be housed in the recess, and the rotary shaft of the body portion of the air blower apparatus is mounted on the fan by housing the projection of the body portion of the air blower apparatus in the recess of the fan. 
     The second invention is explained with reference to FIG.  2 . 
     With the second invention, the fan boss  41  in the rotational center portion of the fan  29  is formed to have a recess. Meanwhile, the substantially central part, that is, a boss  38 , of the body portion  21  of the air blower apparatus  20  is formed to have a projection that is housed in the recessed fan boss  41 . The projecting boss  38  of the body portion  21  of the air blower apparatus  20  is housed within the recessed fan boss  41  in the rotational center portion of the fan  29  and thereby the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29 . The air blower apparatus  20  is constituted in this way. 
     With the second invention, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be reduced because the boss  38  of the body portion  21  of the air blower apparatus  20  is contained within the fan boss  41  of the fan  29 . The space occupied by the air blower apparatus  20  can be made small because of the small width of the air blower apparatus  20  in the direction of the rotary shaft. 
     For the third invention, in the air blowing apparatus according to the second invention, the abovementioned hydraulic motor is mounted substantially in the central part of the body portion of the air blower apparatus. 
     The third invention is explained with reference to FIG.  2 . 
     With the third invention, the hydraulic motor  23  is mounted substantially in the central part of the body portion  21  of the air blower apparatus  20 . 
     Consequently, with the third invention, all or part of the body portion  21  of the air blower apparatus  20 , wherein the hydraulic motor  23  is mounted, is contained within the fan boss  41  of the fan  29 . As a result, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small. Because the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small, the space occupied by the air blower apparatus  20  also can be made small. 
     For the fourth invention, in the air blowing apparatus according to the second invention, the abovementioned hydraulic motor is mounted on the body portion of the air blower apparatus, so as to lie substantially within the total width of the body portion of the air blower apparatus in the direction of the rotary shaft and the width of the abovementioned fan in the direction of the rotary shaft, when the rotary shaft of the body portion of the air blower apparatus is mounted on the abovementioned fan. 
     The fourth invention is explained with reference to FIG.  2 . 
     With the fourth invention, the hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20 , so as to lie substantially within the total width of the width of the body portion  21  of the air blower apparatus  20  in the direction of the rotary shaft and the width W of the fan  29  in the direction of the rotary shaft, when the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29 . 
     With the fourth invention, the necessary space can be further reduced because the hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20  so as to lie substantially within the same. 
     For the fifth invention, in the air blowing apparatus according to the second invention, a power transmission device is provided on the body portion of the air blower apparatus so as to transmit the power of the abovementioned hydraulic motor to the abovementioned rotary shaft. 
     The fifth invention is explained with reference to FIG.  6 . 
     With the fifth invention, a power transmission device  57 A, for transmitting the power of the hydraulic motor  23  to the rotary shaft  39 , is provided on the body portion  21  of the air blower apparatus  20 . 
     With the fifth invention, the necessary space can be made small even with the addition of a power transmission device such as a transmission. 
     For the sixth invention, in the air blowing apparatus according to the second invention, the abovementioned fan is contained within a shroud, while the body portion of the air blower apparatus is fixed to the inner walls of the shroud. 
     The sixth invention is explained with reference to FIG.  2 . 
     With the sixth invention, the fan  29  is contained within the shroud  28  and the body portion  21  of the air blower apparatus  20  is fixed to the inner walls of the shroud  28 . This means that the fan  29  can be caused to rotate within the shroud  28 , and therefore the blowing efficiency of the air blower apparatus  20  can be improved. Further, because the body portion  21  of the air blower apparatus  20  is fixed to the inner walls of the shroud  28 , the air blower apparatus  20  can be securely fixed within the shroud  28 . 
     In order to achieve the abovementioned object, the seventh invention of the present invention is an air blower apparatus comprising a hydraulic motor and a body portion provided with a power transmission device for transmitting power of the hydraulic motor to a rotary shaft of the body portion, the hydraulic motor being mounted on the power transmission device; the rotary shaft of the body portion which the hydraulic motor is mounted on being mounted on a fan, whereby the fan is rotated by driving the hydraulic motor, wherein a rotational center portion of the fan is formed with a recess; a part of the body portion of the air blower apparatus, where the power transmission device is provided, is formed into a projection to be housed in the recess, and the rotary shaft of the body portion of the air blower apparatus is mounted on the fan by housing the projection of the body portion of the air blower apparatus within the recess of the fan. 
     The seventh invention is explained with reference to FIG.  6 . 
     With the seventh invention, the fan boss  41  in the rotational center portion of the fan  29  is formed into a recess. Meanwhile, the portion of the body portion  21  of the air blower apparatus  20  where the power transmission device  57 A is provided, in effect the power transmission device  57 A and boss portion  38 , is formed into a projection that is housed in the recessed fan boss  41 . The projecting power transmission device  57 A and boss portion  38  of the body portion  21  of the air blower apparatus  20  are therefore contained within the recessed fan boss  41  in the rotational center portion of the fan  29 , and thereby the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29 . The air blower apparatus  20  is constituted in this way. 
     With the seventh invention, the power transmission device  57 A and boss portion  38  of the body portion  21  of the air blower apparatus  20  are housed within the fan boss  41  of the fan  29 . As a result, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small. In effect, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small because the power transmission device  57 A such as a transmission usually requiring much space can be housed within the fan boss  41 . Since the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small, the space occupied by the air blower apparatus  20  also can be made small. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the entire configuration including an air blower apparatus of the present invention; 
     FIG. 2 shows a cross sectional view of the air blower apparatus according to the first embodiment; 
     FIG. 3 shows the air blower apparatus in FIG. 2 as viewed in the direction of arrow A; 
     FIG. 4 is a perspective view of a shroud shown in FIG. 2; 
     FIG. 5 is a cross sectional view of the air blower apparatus according to the second embodiment; 
     FIG. 6 is a cross sectional view of the air blower apparatus according to the third embodiment; 
     FIG. 7 is a cross sectional view of the air blower apparatus according to the fourth embodiment; and 
     FIG. 8 is a cross sectional view of a conventional air blower apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the air blower apparatus according to the present invention is explained below. 
     FIG. 1 shows a cross sectional view of the entire configuration including the air blower apparatus according to the present invention. The apparatus shown in FIG. 1 would be mounted in construction machinery or industrial vehicles, for example. 
     As shown in FIG. 1, a box-shaped noise proofing chamber  5  is formed of noise proofing walls  1 ,  2 ,  3  and  4 . The noise proofing walls  1 ,  2 ,  3 , and  4  are formed of soundproof materials. Glass wool, vibration proof rubber panels, or Helmholtz resonators, for example, can be used as the soundproof materials. 
     The interior of the noise proofing chamber  5  is divided into a radiator chamber  7  and engine chamber  8  by means of a soundproof partition wall  6 . Accordingly, the radiator chamber  7  and engine chamber  8  are made soundproof by the noise proofing walls  1 ,  2 ,  3 ,  4 , and  5 . 
     A radiator  9  is disposed within the radiator chamber  7 . An air intake opening  10  is formed in the noise proofing wall  3  constituting the radiator chamber  7 . 
     An engine  11 , a hydraulic pump  12  driven by the engine  11 , and a hydraulic pump  13  for the air blower apparatus that is driven by the engine  11  are disposed within the engine chamber  8 . An air exhaust outlet  14  is formed in the noise proofing wall  1  constituting the engine chamber  8 . A generator, compressor, or the like can be used instead of the hydraulic pumps  12 ,  13 . 
     Cooling water for the engine  11  is circulated within the radiator  9  by a cooling pump, not shown. 
     An inlet port for the hydraulic pump  12  and an inlet port for the hydraulic pump  13  of the air blower apparatus are connected to a tank outside of the noise proofing chamber  5  by pipe lines, not shown. 
     The radiator  9  communicates with the engine  11 , and hydraulic pumps  12 ,  13  via a duct  15 . 
     Specifically, an opening  15 A at one end of the duct  15  is attached to an air outlet side  9 A of the radiator  9 . The duct  15  passes through a hole  6 A in the soundproof partition wall  6 . An opening  15 B at the other end of the duct  15  opposes to the engine  11  and hydraulic pumps  12 ,  13 . 
     The duct  15  comprises a first duct case  15 - 1  and a second duct case  15 - 2 . The second duct case  15 - 2  has a substantially U-shape. The first duct case  15 - 1  and the second duct case  15 - 2  are connected by a shroud  28  within the interior of the engine chamber  8 . The air blower apparatus  20  is provided at the location where the first duct case  15 - 1  and second duct case  15 - 2  are connected. 
     The air blower apparatus  20  is constituted of a body portion  21 , a fan  29 , and a hydraulic motor  23 . 
     The construction of the air blower apparatus  20  is explained below with reference to FIGS. 2,  3 , and  4 . 
     FIG. 2 is a cross sectional view of the air blower apparatus  20 . 
     As shown in FIG. 2, the cylindrical shroud  28  is connected to the first duct case  15 - 1 . 
     FIG. 4 is a perspective view of the shroud  28  in FIG.  2 . 
     As shown in FIG. 4, a plurality of radial ribs  32  is provided on the inside of the shroud  28 . Furthermore, a mounting plate  31  connected to a plurality of ribs  32  is provided in the shaft center of the shroud  28 . The fan  29  is housed within the shroud  28 . 
     FIG. 3 is a view of FIG. 2 as seen in the direction of arrow A. 
     As shown in FIG. 3, the body portion  21  of the air blower apparatus  20  is constituted with a disk-shaped inside plate  24  and a ring-shaped outside plate  25  connected integrally by a plurality of radial ribs  26 . The second duct case  15 - 2  is connected via a bracket  42  to the outside plate  25  of the body portion  21  of the air blower apparatus  20 . 
     The inside plate  24  of the body portion  21  of the air blower apparatus  20  is fixed by the bolts  40  to a mounting plate  31  of the shroud  28 . As above, the body portion  21  of the air blower apparatus  20  is fixed to the inner walls of the shroud  28 . 
     A fan boss  41  is provided on the rotational center portion of the fan  29 . The fan boss  41  projects in the form of a cylinder toward the first duct case  15 - 1  side while it is recessed towards the second duct case  15 - 2  side. 
     The hydraulic motor  23  is mounted on the central portion of the inside plate  24  of the body portion  21  of the air blower apparatus  20 . The hydraulic motor  23  is mounted on the body portion  21  from the second duct case  15 - 2  side. 
     The hydraulic motor  23  is a geared hydraulic motor having a pair of gears  37 ,  37 ′ provided rotatably within the housing  36 . The discharge pressure oil from the hydraulic pump  13  for the air blower apparatus  20  is supplied via a pipe line  44  to the interlocking portions of the gears  37 ,  37 ′ of the hydraulic motor  23 . The hydraulic motor  23  is rotated thereby. The returning pressure oil of the hydraulic motor  23  is returned to the tank outside the noise proofing chamber  5  via a pipe line  45 . 
     A boss portion  38  is formed on the inside plate  24 . The boss portion  38  is formed to project towards the first duct case  15 - 1  side so as to be housed within the recessed fan boss  41 . The boss portion  38  is formed on the central portion of the body portion  21  of the air blower apparatus  20  where the hydraulic motor  23  is mounted. In other words, the output shaft, or the rotary shaft of the gear  37 ′, of the hydraulic motor  23  is provided in the center of the boss portion  38 . 
     The rotary shaft  39  of the fan  29  is provided rotatably at the center of the boss portion  38 . In effect, the rotary shaft  39  is coaxial to the rotary shaft of one gear  37 ′ of the hydraulic motor  23 . The rotary shaft  39  is connected to the rotary shaft of the gear  37 ′. The bearings, sealant, and so forth for the rotary shaft  39  are provided within the boss portion  38 . 
     The rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29  by housing the boss portion  38  of the body portion  21  of the air blower apparatus  20  inside the fan boss  41  of the fan  29 . 
     The inside plate  24  of the body portion  21  of the air blower apparatus  20  is mounted on the mounting plate  31  of the shroud  28 , so that the rotary shaft  39  is located at the center of bore of the shroud  28 . Thereby, the rotational center of the fan  29  can be located at the center of bore of the shroud  28  when the fan  29  is mounted on the rotary shaft  39  of the body portion  21  of the air blower apparatus  20 . Because the rotational center of the fan  29  can be disposed at the inner diameter center of the shroud  28 , there is no risk of the outer periphery of the fan  29  contacting the inner surface of the shroud  28  even if the space between the inner surface of the shroud  28  and the outer diameter of the fan  29 , in effect the tip clearance t, is small. For this reason, the tip clearance t can be made extremely small. If tip clearance t is large, the air blower apparatus  20  will suffer a high energy loss in the direction of the circumference and reduced blowing efficiency. With the present embodiment, the energy loss in the direction of the circumference becomes small and the blowing efficiency of the air blower apparatus  20  can be improved because tip clearance t can be made small. 
     The operation of the first embodiment is explained next. 
     When the engine  11  is driven, pressure oil is discharged from the hydraulic pump  12  and the hydraulic pump  13  for air blower apparatus. The pressure oil discharged from the hydraulic pump  12  is supplied to the outside of the noise proofing chamber  5  via the pipe line  43 . The pressure oil discharged from the hydraulic pump  13  for the air blower apparatus is supplied to the hydraulic motor  23  via the pipe line  44 . Accordingly, the hydraulic motor  23  rotates. 
     When the hydraulic motor  23  rotates, power is transmitted from the gears  37 ,  37 ′ of the hydraulic motor  23  to the rotary shaft  39  and the rotary shaft  39  rotates. Accordingly, the fan  29  mounted on the rotary shaft  39  rotates. 
     When the fan  29  rotates, air is drawn from the air intake opening  10 , passing through the radiator  9  and first duct case  15 - 1 , to the fan  29 . The air drawn by the fan  29  passes through the second duct case  15 - 2  and blows on the engine  11 , hydraulic pump  12 , and hydraulic pump  13  for air blower apparatus. The air in the engine chamber  8  is exhausted from the air exhaust outlet  14 . The location of the air exhaust outlet  14  is determined such that the air passing through the second duct case  15 - 2  and reaching the engine  11  can be exhausted. The size and number of air exhaust outlets  14  is determined based on the quantity of air discharged from the second duct case  15 - 2 , the sizes of the engine  11 , hydraulic pump  12 , and hydraulic pump  13  for air blower apparatus, and the structure around the noise proofing chamber  5 . 
     With the first embodiment, the fan  29  is mounted on the rotary shaft  29  by housing the central portion of the body portion of the air blower apparatus where the hydraulic motor  23  is mounted, meaning the boss portion  38 , within the fan boss  41  of the fan  29 , as shown in FIG.  2 . Accordingly, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small. The space necessary for the air blower apparatus  20  also can be made small because the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small. 
     Moreover, with the first embodiment, the hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20  as shown in FIG. 2, so as to lie substantially within the total width of the width of the body portion  21  of the air blower apparatus  20  in the direction of the rotary shaft, when the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29 , and the width W of the fan  29  in the direction of the rotary shaft. Because the hydraulic motor  23  is mounted so as to lie within the body portion  21  of the air blower apparatus  20 , the space necessary for the air blower apparatus  20  also can be made small. 
     Also, with the first embodiment, the fan  29  is housed within the shroud  28  and the body portion  21  of the air blower apparatus  20  is fixed to the inner walls of the shroud  28  as shown in FIG.  2 . In other words, the blowing efficiency of the air blower apparatus  20  is improved because the fan  29  can be caused to rotate within the shroud  28 . Because the body portion  21  of the air blower apparatus  20  is fixed to the inner walls of the shroud  28 , the air blower apparatus  20  can be securely fixed inside the shroud  28 . 
     The second embodiment is explained next. 
     FIG. 5 is a cross sectional view of the air blower apparatus  20  according to the second embodiment. FIG. 5 corresponds to FIG.  2 . 
     As shown in FIG. 5, the outside plate  25  of the body portion  21  of the air blower apparatus  20  and shroud  28  are formed as one piece. The outer periphery of the outside plate  25  of the body portion  21  of the air blower apparatus  20  is formed as a flange. The flange  15 C of the second duct case  15 - 2  is attached by bolts to the flange-shaped outside plate  25  on the outer periphery of the body portion  21  of the air blower apparatus  20 . As above, the second duct case  15 - 2  is connected to the shroud  28  and the body portion  21  of the air blower apparatus  20  is formed as one piece with the inner walls of the shroud  28 . 
     The fan boss  41  is provided on the rotational center portion of the fan  29 . The fan boss  41  projects in the form of a cylinder towards the first duct case  15 - 1  side and is recessed towards the second duct case  15 - 2  side. 
     The hydraulic motor  23  is mounted on the central portion of the body portion  21  of the air blower apparatus  20 . The hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20  from the second duct case  15 - 2  side. 
     The boss portion  38  is formed on the inside plate  24 . The boss portion  38  is formed to project toward the first duct case  15 - 1  side so as to be contained in the recessed fan boss  41 . The boss portion  38  is formed on the central portion of the body portion  21  of the air blower apparatus  20  where the hydraulic motor  23  is mounted. 
     The rotary shaft  39  of the fan  29  is provided rotatably on the boss portion  38 . The rotary shaft  39  is connected to the output shaft of the hydraulic motor  23 . 
     The rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29  by housing the boss portion  38  of the body portion  21  of the air blower apparatus  20  inside the fan boss  41  of the fan  29 . 
     Consequently, as in the first embodiment, when the engine  11  is driven, pressure oil is discharged from the hydraulic pump  13  for air blower apparatus and the hydraulic motor  23  is rotated thereby. When the hydraulic motor  23  rotates, the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  rotates and the fan  29  mounted on the rotary shaft  39  rotates accordingly. 
     With the second embodiment, as with the first embodiment, the fan  29  is mounted on the rotary shaft  39  by housing the central portion of the body portion  21  of the air blower apparatus  20  where the hydraulic motor  23  is mounted, in effect the fan boss  38 , within the fan boss  41  of the fan  29 . Accordingly, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small. The space necessary for the air blower apparatus  20  also can be made small because the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small. 
     Moreover, with the second embodiment, the hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20  as shown in FIG. 5, so as to lie substantially within the total width of the width of the body portion  21  of the air blower apparatus  20  in the direction of the rotary shaft, when the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29 , and the width W of the fan  29  in the direction of the rotary shaft. The space necessary for the air blower apparatus  20  can be made small because the hydraulic motor  23  is mounted so as to lie substantially within the body portion  21  of the air blower apparatus  20 . 
     Also, with the second embodiment, the fan  29  is housed within the shroud  28  and the body portion  21  of the air blower apparatus  20  is formed as a single piece with the shroud  28 . In other words, the fan  29  can be caused to rotate within the shroud  28  and therefore the blowing efficiency of the air blower apparatus  20  is improved. Further, because the body portion  21  of the air blower apparatus  20  is formed as one piece with the inner walls of the shroud  28 , the air blower apparatus  20  can be securely fixed inside the shroud  28 . 
     The third embodiment is explained next. 
     FIG. 6 is a cross sectional view of the air blower apparatus  20  according to the third embodiment. FIG. 6 corresponds to FIG.  2 . 
     As shown in FIG. 6, the outside plate  25  of the body portion  21  of the air blower apparatus  20  and shroud  28  are formed as one piece. The outer periphery of the outside plate  25  of the body portion  21  of the air blower apparatus  20  is formed as a flange. The flange  15 C of the second duct case  15 - 2  is attached by bolts to the flange-shaped outside plate  25  on the outer periphery of the body portion  21  of the air blower apparatus  20 . As above, the second duct case  15 - 2  is connected to the shroud  28  and the body portion  21  of the air blower apparatus  20  is formed as one piece with the inner walls of the shroud  28 . 
     The fan boss  41  is provided on the rotational center portion of the fan  29 . The fan boss  41  projects towards the first duct case  15 - 1  side and is recessed towards the second duct case  15 - 2  side. 
     Moreover, the fan boss  41  is formed to function as a spinner. By forming the fan boss  41  as a spinner, the resistance to the suction air drawn through the first duct case  15 - 1  by the fan  29  can be made lower. 
     The hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20 . The hydraulic motor  23  is mounted on the body portion  21  of the air blower apparatus  20  from the second duct case  15 - 2  side. 
     The power transmission device  57 A for transmitting power from the output shaft  39 A of the hydraulic motor  23  to the rotary shaft  39  is provided on the body portion  21  of the air blower apparatus  20 . The power transmission device  57 A is provided on the first duct case  15 - 1  side of the body portion  21  of the air blower apparatus  20 . The power transmission device  57 A is a geared transmission, for example, and can be either a speed increasing or decreasing device with changes to the diameters of the master gears and slave gears. Moreover, power may be transmitted with belts instead of gears. 
     The boss portion  38  is formed on the inside plate  24 . The boss portion  38  is formed on the central portion of the body portion  21  of the air blower apparatus  20  so as to project towards the first duct case  15 - 1  side. The rotary shaft  39  of the fan  29  is provided rotatably on the boss portion  38 . The power transmission device  57 A is connected to the rotary shaft  39 . The power transmission device  57 A and the boss portion  38  are formed to project towards the first duct case  15 - 1  side so as to be housed within the recessed fan boss  41 . 
     The rotary shaft  39  of the body portion  21  of the air blower apparatus  20  is mounted on the fan  29  by housing the power transmission device  57 A and the boss portion  38  of the body portion  21  of the air blower apparatus  20  inside the fan boss  41  of the fan  29 . 
     Consequently, as in the first embodiment, when the engine  11  is driven, pressure oil is discharged from the hydraulic pump  13  for air blower apparatus and the hydraulic motor  23  is rotated thereby. When the hydraulic motor  23  rotates, the rotary shaft  39  of the body portion  21  of the air blower apparatus  20  rotates and the fan  29  mounted on the rotary shaft  39  rotates accordingly. 
     With this third embodiment, the fan  29  is mounted on the rotary shaft  39  by housing the power transmission device  57 A and boss portion  38  of the body portion  21  of the air blower apparatus  20  within the fan boss  41  of the fan  29 . Accordingly, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small. In effect, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small because the power transmission device  57   a,  such as a transmission, that usually requires some space can be housed within the fan boss  41 . The space necessary for the air blower apparatus  20  can therefore be made small because the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small. 
     Also, with the third embodiment, the fan  29  is contained within the shroud  28  and the body portion  21  of the air blower apparatus  20  is formed as a single piece with the shroud  28 , as shown in FIG.  6 . In other words, the fan  29  can be caused to rotate within the shroud  28  and therefore the blowing efficiency of the air blower apparatus  20  is improved. Also, the air blower apparatus  20  can be securely fixed within the shroud  28  because the body portion  21  of the air blower apparatus  20  and the inner walls of the shroud  28  are formed as a single piece. 
     The fourth embodiment is explained next. 
     FIG. 7 is a cross sectional view of the air blower apparatus  20  according to the fourth embodiment. FIG. 7 corresponds to FIG.  2 . 
     In the first through third embodiments, the body portion  21  of the air blower apparatus  20  is formed as a single piece. In the fourth embodiment shown in FIG. 7, however, the body portion is divided into the body portion  21  and body portion  64 . 
     The body portion  21  is constituted with the disk-shaped inside plate  24  and ring-shaped outside plate  25  connected integrally by a plurality of radial ribs  26 , like in FIG.  3 . The inside plate  24  of the body portion  21  is fixed by bolts  40  to the mounting plate  31  of the shroud  28 . 
     The outer periphery of the outside plate  25  of the body portion  21  is in the form of a flange. The flange  15 C of the second duct case  15 - 2  is attached by bolts to the flange-shaped outside plate  25  on the outer periphery of the body portion  21 . 
     One end of the rotary shaft  39  of the fan  29  is supported rotatably in the central portion of the body portion  21  of the air blower apparatus  20 . 
     The body portion  64  of the air blower apparatus  20  is formed in the same way as the body portion  21  of the air blower apparatus  20 . Specifically, like in FIG. 3, the body portion  64  is constituted with the disk-shaped inside plate  62  and ring-shaped outside plate  65  being connected with a plurality of radial ribs  63 . The outside of the outside plate  65  of the body portion  64  is in the form of a flange. The flange  15 D of the first duct case  15 - 1  is fixed by bolts to the flange-shaped outside plate  65  on the outer periphery of the body portion  64  of the air blower apparatus  20 . 
     The other end of the rotary shaft  39  of the fan  29  is supported rotatably in the central portion of the inside plate  62  of the body portion  21 . 
     As above, the first duct case  15 - 1  and second duct case  15 - 2  are connected to the shroud  28 , and the body portions  21  and  64  of the air blower apparatus  20  are fixed to the inside walls of the shroud  28 . 
     The fan boss  41  is provided on the rotational center portion of the fan  29 . The fan boss  41  projects in the form of a cylinder toward the second duct case  15 - 2  and is recessed towards the first duct case  15 - 1 . 
     The hydraulic motor  23  is mounted on the central portion of the inside plate  62  of the body portion  64 . The hydraulic motor  23  is mounted on the body portion  64  of the air blower apparatus  20  from the first duct case  15 - 1  side. A spinner  55  is provided on the inside plate of the body portion  64  so as to cover the hydraulic motor  23 . The spinner  55  is provided on the body portion  64  so as to project towards the first duct case  15 - 1  side. The spinner  55  functions to reduce the resistance to the suction drawn through the first duct case  15 - 1  by the fan  29 . 
     The boss portion  38  is formed on the inside plate  62  of the body portion  64 . The boss portion  38  is formed to project towards the second duct case  15 - 2  side so as to be contained within the recessed fan boss  41 . The boss portion  38  is formed in the central portion of the body portion  64  of the air blower apparatus  20  where the hydraulic motor  23  is mounted. 
     The rotary shaft  39  of the fan  29  is provided on the center of the boss portion  38 . The output shaft  39 A of the hydraulic motor  23  is disposed at the center of the boss portion  38 . In effect, the rotary shaft  39  is coaxial with the output shaft  39 A of the hydraulic motor  23  and the rotary shaft  39  is connected to the output shaft  39 A. 
     The rotary shaft  39  is mounted on the fan  29  by housing the boss portion  38  of the body portion  64  within the fan boss  41  of the fan  29 . 
     Consequently, as in the first embodiment, when the engine  11  runs, pressure oil is discharged from the hydraulic pump  13  for the air blower apparatus and the hydraulic motor  23  is rotated thereby. When the hydraulic motor  23  rotates, the rotary shaft  39  of the body portion  21  rotates and the fan  29  mounted on the rotary shaft  39  rotates accordingly. 
     With the fourth embodiment, like the first embodiment, the fan  29  is mounted on the rotary shaft  39  by housing the central portion of the body portion  64  where the hydraulic motor  23  is mounted, in effect the boss portion  38 , within the fan boss  41  of the fan  29 . Accordingly, the width of the air blower apparatus  20  in the direction of the rotary shaft  39  can be made small. The space necessary for the air blower apparatus  20  can be made small because the width of the air blower apparatus  20  in the direction of the rotary shaft becomes small. 
     Also, with the fourth embodiment, the fan  29  is contained within the shroud  28  and the body portions  21  and  64  are formed in the shroud  28 , as shown in FIG.  7 . In other words, the blowing efficiency of the air blower apparatus  20  is improved because the fan  29  can be caused to rotate within the shroud  28 . Also, the air blower apparatus  20  can be securely attached within the shroud  28  because the body portions  21  and  64  of the air blower apparatus  20  are fixed to the shroud  28 .