Patent Publication Number: US-9428883-B2

Title: Construction machine including air cleaner

Description:
TECHNICAL FIELD 
     The present invention relates to a construction machine including an air cleaner. 
     BACKGROUND ART 
     There is conventionally known a construction machine including an engine and an air cleaner connected to the engine via a pipe. Thus provided air cleaners and pipes thereof for construction machines are disclosed in Japanese Utility Model Application Laid-open No. S63-48965. The air cleaner and the pipe therefor are often interposed between a plurality of obstacles within a limited space in the construction machine, as shown in Japanese Utility Model Application Laid-open No. S63-48965; hence, desired is an art which enables the installation thereof to be efficiently performed. 
     SUMMARY OF INVENTION 
     An object of the present invention is to provide a construction machine including an air cleaner and a pipe therefor, the construction machine allowing the air cleaner and the pipe to be efficiently installed while they are interposed between a plurality of obstacles. 
     Provided by the present invention is a construction machine including: an engine; an air cleaner having an exhaust port and configured to filter air taken in by the engine; a pipe connected to the exhaust port of the air cleaner; a seat plate on which the engine, the air cleaner and the pipe are mounted to form a subassembly; a device including an upper surface on which the subassembly is mounted, the device being configured to form, in cooperation with the installed subassembly, a device-assembly to be installed in a predetermined installation space; a fixing member for fixing the subassembly to the device. One of the seat plate and the surface of the device is provided with an aperture extending in a specific length direction and the other of the seat plate and the surface of the device is provided with a fit-in portion to be fitted into the aperture so as to be capable of relative displacement to the aperture in the length direction. The length direction is such a direction that the relative displacement of the fit-in portion to the aperture in the length direction allows the subassembly to be displaced between a first position and a second position, the first position being farther from a first structure, which is an obstacle to the installation of the subassembly into the installation space, and being closer to a second structure other than the first structure, than the second position. The fixing member has both of a first fixing mode of fixing the subassembly to the device at the first position and a second fixing mode of fixing the subassembly to the device at the second position. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an upper slewing body of an excavator according to an embodiment of the present invention; 
         FIG. 2  is a plan view of the upper slewing body; 
         FIG. 3  is an exploded perspective view of a device-assembly of the excavator; 
         FIG. 4  is a perspective view showing a state of mounting a subassembly included in the device-assembly on an upper surface of a fuel tank at a first position; 
         FIG. 5  is a perspective view showing a state where the subassembly has been displaced to the second position; 
         FIG. 6  is a front view showing the state shown in  FIG. 5 ; 
         FIG. 7  is a plan view showing the state shown in  FIG. 4 ; 
         FIG. 8  is a plan view showing the state shown in  FIG. 5 ; 
         FIG. 9  is an enlarged view of a cross section along the line IX-IX in  FIG. 8 ; 
         FIG. 10A  and  FIG. 10B  are perspective views each showing a pipe constituting the subassembly. 
         FIG. 11  is a schematic side view of an excavator according to a comparison example for explaining the present invention; 
         FIG. 12  is a schematic plan view of the excavator shown in  FIG. 11 ; 
         FIG. 13  is a perspective view of an air cleaner and a pipe of the excavator shown in  FIG. 12 ; and 
         FIG. 14  is a plan view of the air cleaner and the pipe of the excavator shown in  FIG. 12 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention will be described. In advance of the description about the embodiments, explained is an excavator according to a comparative example virtually assumed for describing the embodiments, with reference to  FIGS. 11 to 14 . 
     The excavator includes a crawler-type lower travelling body  1 , an upper slewing body  2  mounted on the lower travelling body  1  slewably about an axis perpendicular to the ground, and a working attachment  9  loaded on a front portion of the upper slewing body  2 . The attachment  9  has a boom  3 , an arm  4 , a bucket  5 , and a plurality of cylinders, namely, a boom cylinder  6 , an arm cylinder  7  and a bucket cylinder  8 , which operate the boom  3 , the arm  4  and the bucket  5 , respectively. 
     The upper slewing body  2  has an upper frame  10  as a base, and various devices and equipment which are mounted on the upper frame  10 . Specifically, on the upper frame  10  are mounted an engine room  12  and a cabin  17 . The engine room  12  is provided on a rear portion of the upper frame  10 , having a bonnet  11  adapted to open and close an opening which faces upward. In the engine room  12 , there are installed an engine  13  as a power source, and related equipment of the engine  13 , namely, a radiator  14 , a cooling fan  15 , a hydraulic pump  16 , etc. The cabin  17  is installed forward of the engine room  12 , and at one of right and left sides (usually, at the left side; hereinafter, the description will be based on this assumption). In the present specification, “front and rear” and “right and left” are directions from the viewpoint of an operator who is seated in the cabin  17 . 
     In the upper frame  10 , there are further provided a hydraulic tank  18 , a fuel tank  19 , a center foothold  20 , and a climbing step  21 . The hydraulic tank  18  is placed on an opposite side to the cabin  17  with respect to the right and left direction (usually, at the right side) in the upper frame  10 , and located forward of the engine room  12 , and accumulates hydraulic fluid. The fuel tank  19  is arranged with the hydraulic tank  18  in the front and rear direction, and accumulates a fuel. The fuel tank  19  includes an oil feeding portion  19   a  with an oil feeding port. The center foothold  20  is provided on a widthwise intermediate portion of the upper frame  10  immediately forward of the engine room  12 , in order to allow maintenance of devices including the engine  13  in the engine room to be performed. The climbing step  21  is disposed forward of the fuel tank  19  and formed into a stair shape for guiding a maintenance person to the center foothold  20 . Thus formed is a path for maintenance which reaches the center foothold  20  through the climbing step  21  and the upper surface of the fuel tank  19 .  FIG. 12  indicates a thick line surrounding the path and the center foothold  20  to distinguish them from other parts. 
     Over the upper frame  10 , there are arranged an air cleaner  22  and an air intake piping unit  23 . The air cleaner  22  is placed, for example, between the engine room  12  and the cabin  17  at the left side of the upper frame  10 , in order to filter engine intake air. The air intake piping unit  23  interconnects the air cleaner  22  and an air suction port of the engine  13 . 
     The air cleaner  22  has a configuration shown in  FIGS. 13 and 14 . 
     As disclosed in Japanese Patent Application Laid-open No. 2003-184670, the air cleaner  22  includes a main body  24  having a cylindrical outer peripheral surface and accommodating a filter, an air intake portion  25  having an air intake port and protruding upward beyond the outer peripheral surface of the main body  24 , a cylindrical exhaust portion  26  having an exhaust port and provided at one end side of the main body  24 , and an end cover  28  provided on the other end side of the main body  24  and being detachable to allow the filter to be taken in and taken out. An air intake cylinder  27  and the air intake piping unit  23  are connected to the air intake portion  25  and the exhaust portion  26 , respectively. 
     It is desirable to perform the maintenance of the air cleaner  22  (take-in and take-out of the filter) at the center foothold  20  from the aspect of working efficiency and safety; hence, the air cleaner  22  is usually oriented in such a posture that the end cover  28  faces the center-foothold- 20  side while an exhaust port of the exhaust portion  26  faces the opposite side to the center foothold  20 , i.e., to the outside of the machine body. 
     The air intake piping unit  23  includes an air-cleaner-side pipe  29  and an engine-side pipe  30 . The air-cleaner-side pipe  29  is arranged in an air cleaner installation space S 1 , having a basal end portion which is connected to the exhaust port of the air cleaner  22 . The engine-side pipe  30  is arranged in the engine room  12  over substantially the whole length of the engine-side pipe  30 , interconnecting the air-cleaner-side pipe  29  and the air intake port of the engine  13 . Specifically, the engine-side pipe  30  has a distal end portion which is connected to the air intake port of the engine  13 . 
     Since the exhaust port of the exhaust portion  26  of the air cleaner  22  is connected to the air-cleaner-side pipe  29  and faces the side opposite to the engine  13 , the air-cleaner-side pipe  29  includes a returning portion  29   a  which returns in a U-shape as shown in the drawings. Across the returning portion  29   a , an end portion at one side of the air-cleaner-side pipe  29  forms a basal end portion which is connected to the exhaust port of the exhaust portion  26  and an end portion at the other side of the air-cleaner-side pipe  29  forms the distal end portion which is connected to the engine-side pipe  30 . Specifically, the air-cleaner-side pipe  29  includes the returning portion  29   a  and a straight-line portion  29   b  which extends horizontally and linearly from the distal end of the returning portion  29   a  to the engine  13  (the engine-side pipe  30 ) side along the air cleaner  22 , at the side opposite to the basal end portion which is connected to the exhaust portion  26 . The sum of respective front-rear sizes of the air cleaner  22  and the air-cleaner-side pipe  29  corresponds to a substantial air-cleaner width size W 1  as shown in  FIG. 14 . The installation space S 1  is, therefore, required to have a front-rear size no less than the air-cleaner width size W 1 . In here, if the air cleaner  22  was oriented so that the exhaust port of the air cleaner  22  faces the engine side, the width size W 1  of the air cleaner could be reduced because of no need for the returning portion  29   a  of the air-cleaner-side pipe  29 . This case, however, involves making the end cover  28  face the outside of the machine body, which requires the maintenance operation of taking in and taking out of the filter to be performed at a high place at the outside of the machine body: this is not advisable from the aspect of safety and working efficiency. 
     On the other hand, excavator are required to receive installation of additional equipment, such as a liquid reducing-agent tank for accumulating a reducing agent for reducing and purifying the exhaust gas and a large-sized battery following hybridization of machines, within the limited space thereof. 
     As means for space utilization, there can be considered arrangement of the air cleaner  22  in the installation space S 1  in the state in which the air cleaner  22  is installed on the upper surface of other equipment such as the fuel tank  19  (three-dimensional arrangement), for example. Specifically, as a desirable procedure of assembling and installing, it would be possible to take the procedure of installing the air cleaner  22  and the air-cleaner-side pipe  29  on the fuel tank upper surface in advance, and then installing the device-assembly consisting of the three items of the fuel tank, the cleaner  22 , and the air-cleaner-side pipe  29  into the installation space S 1 . 
     In this case, because the oil filling part  19   a  protrudes from the upper surface of the fuel tank  19 , the air cleaner  22  needs to be installed on the fuel tank upper surface by separating the air cleaner  22  from the oil filling part  19   a  so as not to interrupt the oil filling and the like. Practically, the oil filling part  19   a  needs to be provided at a front part of the fuel tank upper surface, and the air cleaner  22  needs to be installed at a rear part of the fuel tank upper surface. 
     However, this arrangement brings the air-cleaner-side pipe  29  into a position close to a structure which is positioned at the rear side thereof. Specifically, when the engine room  12  has a front wall, the air-cleaner-side pipe  29  will be close to the front wall. When the engine room  12  has no front wall, the air-cleaner-side pipe  29  will be close to the equipment in the engine room (i.g., the radiator  14 ). This generates a possibility of interference of the air-cleaner-side pipe  29  with the radiator  14  which can damage the air-cleaner-side pipe during the installation of the device-assembly into the installation space S 1 . Avoiding this interference requires an extremely careful installing operation. This operation is troublesome, further involving a risk of damaging the air-cleaner-side pipe  29 . 
     This problem could be solved by increasing the size in the front-rear direction of the installation space S 1  to a size large enough to involve no risk of the interference; the size-increase, however, causes the loss of the space-utilization effect. Even the arrangement of the air-cleaner-side pipe  29  along a path forward of the air cleaner  22  cannot solve the problem because it allows the air cleaner  22  to interfere with the radiator  14 . 
     The excavator according to the embodiment of the present invention solves the above problems. The embodiment will be described with reference to  FIGS. 1 to 10 . In the embodiment, the present invention is applied to an excavator, which has a common configuration with the excavator according to the comparative example shown in  FIGS. 11 to 14 , in the following points. 
     Specifically, the excavator includes a not-graphically shown crawler-type lower travelling body, an upper slewing body  2  mounted on the lower travelling body  1  slewably about an axis perpendicular to the ground. The upper slewing body  2  has an upper frame  10  as a base, on which various devices and equipment are mounted. The various devices and equipment include an engine room  12 , an engine  13  as a power source, related equipment of the engine  13 , a cabin  17 , a plurality of tanks including a hydraulic oil tank  18  and a fuel tank  19 , a center foothold  20 , and a climbing step  21 . The engine room  12  is provided on a rear portion of the upper frame  10 , designed to be opened and closed by a bonnet  11 . The engine  13  and the related equipment are housed in the engine room  12 . The related equipment includes a radiator  14 , a cooling fan  15 , and a hydraulic pump  16 . The cabin  17  is disposed on a front side and the left side of the engine room  12 . The hydraulic oil tank  18  is a tank which accumulates hydraulic oil. The hydraulic oil tank  18  is provided at a position on the opposite side to the cabin  17  with respect to the left and right direction in the upper frame  10 , i.e., at the right side, and forward of the engine room  12 . The center foothold  20  is used for maintenance of devices including the engine  13  in the engine room  12 , and is provided immediately forward of the engine room  12  and on a widthwise intermediate portion of the upper frame  10 . The climbing step  21  is formed into a stair shape to guide the maintenance person to the center foothold  20 , and is disposed forward of the hydraulic oil tank  18 . 
     The fuel tank  19  is a tank which accumulates the fuel. In the present embodiment, the fuel tank  19  is placed in an installation space S 2  defined between the cabin  17  and the engine room  12  over the upper frame  10 , allowing an air cleaner  22 , which filters the intake air of the engine, to be placed on the fuel tank  19 . In other words, while both of the hydraulic oil tank  18  and the fuel tank  19  in the comparative example shown in  FIGS. 11 and 12  are collected at the right side of the upper frame, the hydraulic oil tank  18  and the fuel tank  19  in the present embodiment are distributed on the right and left sides on the upper frame  10 , respectively, and the air cleaner  22  is superposed on the fuel tank  19 , that is, arranged three-dimensionally. The present arrangement enables an empty space forward of the hydraulic oil tank  18 , that is, below the climbing step  21 , to be produced, thus allowing other equipment (either one of or both of a liquid reducing-agent tank and a battery for hybrid machines, for example) to be installed in the produced space. 
     The fuel tank  19  has an oil feeding portion  19   a  being located at a front part of the fuel tank  19  and having an oil filling port. The air cleaner  22  is placed at a rear portion of the fuel tank  19 , i.e., at a portion near the engine room, at a distance from the oil feeding portion  19   a.    
     The air cleaner  22  has a configuration similar to that of the air cleaner  22  shown in  FIGS. 12 to 14 . As specifically shown in  FIGS. 3 to 9 , the air cleaner  22  includes: a main body  24  accommodating a not-graphically-shown filter and having a cylindrical outer peripheral surface; an air intake portion  25  protruding upward beyond the outer peripheral surface of the main body  24  and having an air intake port; an exhaust portion  26  provided at one axial-end side of the main body  24  and having an exhaust port; an air intake cylinder  27  connected to the air intake port; an air intake piping unit  31  connected to the exhaust port; and an end cover  28 . 
     It is desirable that the maintenance of the air cleaner  22 , that is, take-in and take-out of the filter, is performed at the center foothold  20  for the sake of working efficiency and safety; hence, the air cleaner  22  is oriented so that the end cover  28  faces the center foothold  20  side while the exhaust port of the exhaust portion  26  faces the opposite side, that is, the outside of the machine body. 
     The end cover  28  is configured to be attached and detached with respect to the other end side of the main body  24  for taking in and taking out the not-graphically-shown filter. The end cover  28  is attached with an evacuator  28   a  for discharging dusts from the air cleaner  22 , so as to make the evacuator  28   a  protrude downward beyond an under surface of the end cover  28 . 
     The air intake piping unit  31  includes an air-cleaner-side pipe  32  and an engine-side pipe  33 . The air-cleaner-side pipe  32  is arranged in the installation space S 2 , having a basal end portion which is connected to the exhaust port of the exhaust portion  26  of the air cleaner  22 . The engine-side pipe  33  is arranged so as to locate a portion of substantially the whole length thereof in the engine room  12 . The engine-side pipe  33  has a distal end portion which is connected to the air intake port of the engine  13 . The engine-side pipe  33 , thus, interconnects the air-cleaner-side pipe  32  and the air intake port of the engine  13 . 
     The exhaust port of the air cleaner  22 , to which the distal end portion of the air-cleaner-side pipe  32  is connected, faces a side opposite to the engine  13 : hence, the air-cleaner-side pipe  32  has a portion returning in a U-shape as shown in the drawings, wherein the basal end portion as one end portion out of the end portions at both sides of the returning portion is connected to the exhaust port of the exhaust portion  26  while the distal end portion as the other end portion out of the end portions is connected to the engine-side pipe  33 . In detail, the air-cleaner-side pipe  32  includes: the basal end portion which is connected to the exhaust port of the exhaust portion  26 ; a returning portion  32   a  having a shape of returning so as to extend from the basal end portion to the outer-periphery side of the air cleaner  22  toward the engine  13  side; and a straight-line portion  32   b  as a downstream-side portion which extends from a distal end of the returning portion  32   a  along the air cleaner  22  linearly and horizontally to the engine- 13  side and the engine-side-pipe- 30  side. 
     The excavator further includes a seat plate  34 . The seat plate  34  includes an upper surface on which the air cleaner  22  and the air-cleaner-side pipe  32  are mounted. Thus formed are a subassembly A 1  including the air cleaner  22 , air-cleaner-side pipe  32  and the seat plate  34 , namely, an air-cleaner assembly. The subassembly A 1  including the seat plate  34  can be mounted on the upper surface of the fuel tank  19 , thus forming a device-assembly A 2  including the subassembly A 1  and the fuel tank  19 . The entire device-assembly A 2  is installed in the installation space S 2 . 
     Next will be specifically described the subassembly A 1  and the device-assembly A 2 . 
     The seat plate  34  is a plate body formed of a metal or plastic and has a shape and an area which are necessary and sufficient for mounting the air cleaner  22  and the air-cleaner-side pipe  32  on the plate body. The air cleaner  22  and the air-cleaner-side pipe  32  connected to the air cleaner  22  are mounted and fastened on the seat plate  34 , for example, with a bolt. 
     The air-cleaner-side pipe  32  includes a fitting seat  32   c  shown in  FIGS. 7, 8, and 10B . The fitting seat  32   c  protrudes beyond the side surface of the straight line portion  32   b  integrally with the straight line portion  32   b  of the air-cleaner-side pipe  32 . By fastening the fitting seat  32   c  to the seat plate  34  with the bolt, the air-cleaner-side pipe  32  is mounted to the seat plate  34 . It may be permitted to similarly mount a plurality of portions of the air-cleaner-side pipe  32  on the seat plate  34 . 
     The air cleaner  22  is fastened to the seat plate  34  at a plurality of positions with respective bolts, while the structure for mounting the air cleaner  22  is not graphically shown, for simplification of the drawings. 
     The seat plate  34  is provided with an aperture, specifically, a long-hole  35  which is long in the front-rear direction as shown in  FIGS. 3, 7, and 8 . The fuel tank  19  is provided with a cylindrical boss  36  having a screwed hole, on an upper surface of the fuel tank  19 , the boss  36  protruding vertically beyond the upper surface. For fixing the seat plate  34 , used is a bolt  37  which constitutes a fixing member and serves as a fit-in portion. The bolt  37  is screwed into the boss  36  through the long-hole  35  to thereby constrain the entire subassembly A 1  including the seat plate  34  to the upper surface of the fuel tank  19  while permitting a relative displacement of the subassembly A 1  to the fuel tank  19  in the front-rear direction within the range in the longitudinal direction of the long-hole  35 . The bolt  37 , thus, can permit the subassembly A 1  to be displaced between: a first position apart from the radiator  14  as a first structure which becomes an obstacle to the installation of the device-assembly A 2  into the installation space S 2  as shown in  FIGS. 4 and 7  and close to the oil filling portion  19   a  as a second structure; and a second position apart from the oil filling part  19   a  by a distance which prevents the subassembly A 1  from hindering the use of the oil filling part  19   a  as shown in  FIGS. 5 and 8  and close to the radiator  14 . The bolt  37  is able to fix the subassembly A 1  at each of the first and second positions. Specifically, the bolt  37  has a first fixing mode of fixing the subassembly A 1  to the fuel tank  19  at the first position, and a second fixing mode of fixing the subassembly A 1  to the fuel tank  19  at the second position, wherein, the subassembly A 1  is farther from the radiator  14  and closer to the oil feeding portion  19   a  when located at the first position than when located at the second position. 
     The front end portion of the seat plate  34  forms an air-cleaner guard portion  34   a  which protrudes upward beyond the other portion. The air-cleaner guard portion  34   a  and the oil filling part  19   a  restrict a forward position of the seat plate  34  and prevent the air cleaner  22  and the oil filling part  19   a  from collision to each other. 
     The subassembly A 1  is mounted at such a position that the evacuator  28   a  protrudes from the upper surface of the fuel tank  19  to the right side as shown in  FIG. 6  so as to prevent dusts dropped from the evacuator  28   a  of the air cleaner  22  from falling onto the upper surface of the fuel tank  19 . Corresponding to this, a side bracket  38  is mounted on the lower surface of the right side end part of the seat plate  34 , the part protruding from the upper surface of the fuel tank  19 . The side bracket  38  includes a horizontal wall and a vertical wall extending downward from one end of the horizontal wall, mounted to the seat plate  34  by welding or the like so as to extend along the displacement direction of the subassembly A 1 , i.e., the front-rear direction. Specifically, the horizontal wall of the side bracket  38  is mounted to the seat plate  34 , while the vertical wall is provided with through-holes  39 ,  39  shown in  FIG. 3 , for example, at respective front and rear sides of the vertical wall. 
     On the other hand, as shown in  FIG. 3  and the like, the upper part of the right side surface of the fuel tank  19  is provided with two spaced cylindrical first bosses  40  and two spaced cylindrical second bosses  41  in correspondence to the bolt through-holes  39 . As shown in  FIG. 4 , when the subassembly A 1  is at the first position, respective fixing bolts  42  can be screwed into the first bosses  40 ; as shown in  FIG. 5 , when the subassembly A 1  is at the second position, the respective fixing bolts  42  can be screwed into the second bosses  41 . Thus, the subassembly A 1  can be fixed to the fuel tank  19  at any one of the first and second positions. 
     In this structure, the side bracket  38  can support the part of the subassembly A 1  (particularly, the seat plate  34 ) which part protrudes to the right side from the upper surface of the fuel tank  19 , at the lower side thereof. Furthermore, the use of the bolt  37  and the fixing bolts  42  allows the subassembly A 1  to be more securely fixed. 
     The mounting of the subassembly A 1  and the installation of the device-assembly A 2  are performed, for example, in the following procedure. 
     (i) The air cleaner  22  and the air-cleaner-side pipe  32  are mounted on the seat plate  34 , thereby forming the subassembly A 1 . 
     (ii) The subassembly A 1  is mounted the upper surface of the fuel tank  19 , thereby forming the device-assembly A 2 . At the stage of (i), the subassembly A 1  is placed at the first position in  FIGS. 4 and 7  and, if necessary, fixed by the bolt  37 . At the stage of (ii), the subassembly A 1  is fixed or provisionally fixed by at least one of the bolt  37  and the fixing bolts  42 ,  42 . 
     (iii) The device-assembly A 2  is lifted, for example, by the crane and to be installed into the installation space S 2 , and the air-cleaner-side pipe  32  is connected to the engine side pipe  33 . During this installation, the device-assembly A 2  can be reliably prevented from interference with the radiator  14  by respective sizes predetermined so as to locate the seat plate  34  and the air-cleaner-side pipe  32  of the subassembly A 1  apart from the radiator  14  with a sufficient distance as shown in  FIG. 7 . The mounting of the air cleaner  22  and the air-cleaner-side pipe  32  to the seat plate  34  may be performed following the finish of mounting of the seat plate  34  onto the upper surface of the fuel tank  19 . 
     Next will be described a configuration of the air-cleaner-side pipe  32  and a structure for arrangement thereof. 
     The straight-line portion  32   b  of the air-cleaner-side pipe  32  has a cross section shaped into an approximately right-angled triangular, as shown in  FIG. 9 , including a horizontal bottom side portion X, a vertical side portion Z extending vertically upward from one end of the opposite ends of the horizontal bottom side portion X, the one end being opposite to the air cleaner  22 , a hypotenuse portion Y interconnecting the upper end of the vertical side portion Z and the other end of the opposite ends of the horizontal bottom side portion X, i.e., the end being closer to the air cleaner  22 , and respective corner portions which connect mutually adjacent side parts, each corner portion being rounded. The straight-line portion  32   b  is arranged so as to locate at least a part of the hypotenuse portion Y in a space T vertically sandwiched between a cylindrical outer peripheral surface  24   a  of the air cleaner main body  24  and the upper surface of the setting plate  34 , as shown in  FIG. 9 . 
     The exhaust port of the exhaust portion  26  of the air cleaner  22  has a circular cross section, and a basal end portion  32   e  ( FIG. 10 ) of the returning portion  32   a , the basal end portion  32   e  adapted to be connected to the exhaust port, has a circular cross section corresponding to the cross section of the exhaust port; meanwhile, the distal end portion of the returning portion  32   a , joined to the straight-line portion  32   b , is required to have a cross section which matches the cross section of the straight-line portion  32   b , that is, the right-angled triangular cross section, shown in  FIG. 7 . However, sudden change in the shape of the cross section of the returning portion  32   a , which has an original large airflow resistance due to the returning of the pipe line, from a circle to a right-angled triangle with an extreme reduction in the cross-sectional area involves a problem of excessively increasing the airflow resistance of the returning portion  32   a  to lower the aeration performance. 
     For the reason, the returning portion  32   a  according to the present embodiment is given a shape of the cross section which gradually changes from a circle to an approximately right-angled triangle by keeping a substantially constant area from the basal end portion  32   e  to the distal end portion of the returning portion  32   a . Furthermore, the returning portion  32   a  does not have a simple arc curved shape, but has a shape in which the basal end portion  32   e  opens toward the exhaust port of the exhaust portion  26  and the returning portion  32   a  linearly extends from the basal end portion  32   e  to the air-cleaner-outer-periphery side to reach the straight-line portion  32   b , as shown in the drawings. 
     The thus shaped air-cleaner-side pipe  32  can be manufactured as a molded product involving the integration of the returning portion  32   a  and the straight-line portion  32   b  with each other, by injection molding and the like using plastics and rubber as raw materials. Alternatively, the air-cleaner-side pipe  32  can be manufactured by casting using a metal material. 
     The straight-line portion  32   b  has a distal end portion  32   f , which is the opposite end portion to the returning portion  32   a  and adapted to be connected to the engine-side pipe  33 . The distal end portion  32   f  has a circular cross section corresponding to the circular cross section of the engine-side pipe  33 , as shown in  FIGS. 10A and 10B . The distal end side of the straight-line portion  32   b , originally having little bending and has small airflow resistance, is permitted to have a direct change in the shape of the cross section from an approximate triangle to a circle. 
     The present configuration enables the following effects to be obtained. 
     (1) The air cleaner  22 , the air-cleaner-side pipe  32  and the fuel tank  19  can be efficiently assembled and installed by mounting the air cleaner  22  and the air-cleaner-side pipe  32  on the seat plate  34  to form the subassembly A 1 , mounting the subassembly A 1  on the upper surface of the fuel tank  19  to form the device-assembly A 2  and installing the device-assembly A 2  into the installation space S 2 . 
     (2) Setting the subassembly A 1  at the first position apart from the radiator  14  allows the installation of the device-assembly A 2  into the installation space S 2  to be easily performed while surely avoiding the interference of the device-assembly A 2  with the radiator  14 . Furthermore, thereafter displacing the subassembly A 1  to the second position apart from the oil feeding portion  19   a  prevents the subassembly A 1  from hindering fuel feeding. The device-assembly A 2  can be thus installed efficiently and easily while involving no enlargement of the installation space S 2  and avoiding the interference of the air-cleaner-side-pipe  32  and the seat plate  34  of the subassembly A 1  with the radiator  14 . 
     (3) According to the embodiment, the side bracket  38  protrudes downward beyond the lower surface of one end of the seat plate  34  while extending in the direction of the displacement of the subassembly A 1 ; the subassembly A 1  is mounted on the upper surface of the fuel tank  19  in the state where the side bracket  38  and the one end of the seat plate  34  protrude outside the upper surface of the fuel tank  19 ; and the side bracket  38  is allowed to be fixed to the right side surface of the fuel tank  19  either of the first and second positions: these enable the side bracket  38  to support the protruding part of the mounted subassembly A 1  outside the upper surface of the fuel tank  19  and make the fixing of the subassembly A 1  at each of the first and second positions be reliable. 
     (4) According to the embodiment, the air cleaner  22  is oriented so that the exhaust port thereof faces a side opposite to the engine  13 ; the air-cleaner-side pipe  32  includes the end portion connected to the exhaust port, the returning portion  32   a  extending from the end portion to the outer-peripheral-surface-side of the air cleaner  22  toward the engine- 13 -side along the air cleaner  22 , and the straight-line portion  32   b  from the distal end of the returning portion  32   a  to the engine- 13 -side along the air cleaner  22 ; and the air-cleaner-pipe  32  is mounted on the seat plate  34  in the state where at least a part of the straight-line portion  32   b  of the air-cleaner-side pipe  32  is located in the space S between the cylindrical outer peripheral surface  24   a  of the main body  24  of the air cleaner  22  and the upper surface of the seat plate  34 : these allows the total width size W 2  of the pipe  32  and the air cleaner  22  to be small in spite that the air-cleaner-side pipe  32  includes the returning portion  22   b . This enables the subassembly A 1  and hence the device-assembly A 2  to be compact and enables the installation thereof into the installation to be facilitated. Besides, utilizing the space T, which is originally a dead space, as a space for piping the straight-line  32   b  results in a high space-utilization efficiency. 
     (5) The shape of the cross section of the straight-line portion  32   b , being substantially right-angled triangle shape including the vertical side portion Z and the hypotenuse portion Y at least a part of which is inserted into the space S, allows the straight-line portion  32   b  to wedge into the space S in a great depth, thus allowing the protrusion dimension α shown in  FIG. 9  when the air cleaner  22  is viewed from above to be small. This allows the total width size W 2  of the assembly of the air cleaner  22  and the air-cleaner-side pipe  32  to be further reduced, thus making the small-sizing of the subassembly A 1  and the device-assembly A 2  and the facilitation in the installation thereof be more effective. 
     (6) The air-cleaner-side pipe  32 , being an integrated molded product with the continuous integration of the air-cleaner-side pipe  32  and the straight-line portion  32   b  with each other, allows the above width size to be possibly reduced without difficulty, as compared with an air-cleaner-side pipe formed of a flexible hose and bent in a U-shape. Furthermore, the protrusion size of the returning portion  32   a  in the length direction of air cleaner  22  also can be reduced, which is particularly advantageous when the space is limited also in the length direction of the air cleaner  22 . 
     The present invention is, however, not limited to the above-described embodiment but permitted include, for example, the following embodiments. 
     (a) The shape of the cross section of the straight-line portion  32   b  in the air-cleaner-side pipe is not limited to one including respective side portions X, Y and Z. For example, the vertical side portion Z and the bottom side portion X may be changed into an arc-shaped portion. This configuration also permits the total width size of the pipe and the air cleaner to be reduced by the arrangement of the straight-line portion  32   b  with the insertion of at least a part of the hypotenuse portion Y into the space T. The air-cleaner-side pipe, alternatively, may have a circular cross section over a whole length of the air-cleaner-side pipe. Thus shaped air-cleaner-side pipe also can have a reduced width size with the insertion of at least a part of the straight-line portion of the air-cleaner-side pipe into the space. In this case, the air-cleaner-side pipe may be a flexible hose bent in a U-shape, instead of a plastic molded product and the like. 
     (b) The means for permitting the displacement of the subassembly between the first and second positions is not limited to the combination of the long-aperture  35  provided in the seat plate  34  and the bolt  37  screwed into the boss  36  on the upper surface of the fuel tank  19  through the long-aperture  35  in the above embodiment. The displacement is also permitted, for example, by the combination of a bracket having a long-aperture and provided at an upper-surface-side of the fuel tank, a screwed hole provided in the seat plate, and a bolt screwed into the screwed hole with engagement with the long-aperture. In this case, fixing the seat plate at the first and second positions can be performed by another fixing member, for example, means for fixing in the side bracket  38  in the embodiment or at a plurality of positions including one in the side bracket  38 . 
     (c) In the invention, the first and second structures as obstacles to the installation of the device-assembly are not limited to the radiator  14  and the oil feeding portion  19   a , respectively. The first and second structures may be variably defined in accordance with a lay-out of circumstance equipment thereof and the like, and the subassembly A 1  can be modified according to the structures. 
     (d) While the device-assembly A 2  in the embodiment is formed of the subassembly A 1  and the fuel tank  19 , the assembly according to the invention may be mounted on an upper surface of a device other than a fuel tank, such as a hydraulic fluid tank, to form a device-assembly. 
     (e) The present invention can be applied to not only an excavator but also various construction machines configured by utilization of the excavator, similarly to the above embodiments. 
     As described above, the present invention provides a construction machine including an air cleaner and a pipe therefor, the construction machine allowing the air cleaner and the pipe to be efficiently installed while they are interposed between a plurality of obstacles while surely avoiding the interference the air cleaner or the pipe with the obstacles. The provided construction machine includes: an engine; an air cleaner having an exhaust port and configured to filter air taken in by the engine; a pipe connected to the exhaust port of the air cleaner; a seat plate on which the engine, the air cleaner and the pipe are mounted to form a subassembly; a device including an upper surface on which the subassembly is mounted and configured to form, in cooperation with the installed subassembly, a device-assembly to be installed in a predetermined installation space; a fixing member for fixing the subassembly to the device. One of the seat plate and the surface of the device is provided with an aperture extending in a specific length direction and the other of the seat plate and the surface of the device is provided with a fit-in portion to be fitted into the aperture so as to be capable of relative displacement to the aperture in the length direction. The length direction is such a direction that the relative displacement of the fit-in portion to the aperture in the length direction allows the subassembly to be displaced between a first position and a second position, the first position being farther from a first structure (e.g., a radiator), which is an obstacle to the installation of the subassembly into the installation space, and being closer to a second structure other than the first structure, than the second position. The fixing member has both of a first fixing mode of fixing the subassembly to the device at the first position and a second fixing mode of fixing the subassembly to the device at the second position. 
     In the above construction machine, the air cleaner, the pipe and the device can be efficiently assembled and installed by mounting the air cleaner and the pipe on the common seat plate to form the subassembly, mounting the subassembly on the upper surface of the fuel tank to form the device-assembly and installing the device-assembly into the installation space. In addition, setting the subassembly at the first position apart from the first structure (e.g., a radiator  14 ) allows the installation of the device-assembly into the installation space to be easily performed while surely avoiding the interference of the device-assembly with the first structure. Thereafter, displacing the subassembly to the second position apart from the second structure (e.g., an oil feeding portion of a fuel tank) enables the subassembly to be prevented from hindering the use of the first structure. 
     The construction machine according to the invention, in a preferable embodiment thereof, further includes: a lower travelling body; an upper slewing body mounted on the lower travelling body so as to be slewable and including an upper frame as a base; an engine room provided on a rear portion of the upper frame to accommodate the engine as a power source and related equipment to the engine; a cabin provided on one of a right front portion and a left front portion of the upper frame, wherein: the device is a fuel tank; the device-assembly is installed in the installed space between the engine room and the cabin; the first structure is a structure located in the engine room so as to be close to and opposed to the subassembly installed in the installation space; and the second structure is an oil feeding portion protruding beyond the upper surface of the fuel tank. 
     According to the above preferable embodiment, the device-assembly, which is formed by mounting the air cleaner on the fuel tank, is allowed to be installed between the engine room and the cabin easily while involving no interference of the device-assembly with a structure, for example, a radiator. After the installation, the subassembly can be prevented from hindering fuel feeding by the displacement thereof to locate the subassembly far from the oil feeding portion of the fuel tank. 
     It is preferable that: the fixing member includes a side bracket extending in a direction of the displacement of the subassembly and protruding beyond a lower surface of one end of the seat plate; the subassembly is configured to be mounted on the upper surface of the device in a state where the one end of the seat plate and the side bracket protrude outside the upper surface of the device; and the side bracket is configured to be fixed onto a side surface of the device at each of the first and second positions. The side bracket, in the state where the subassembly is mounted so as to make the one end of the subassembly protrude outside the upper surface of the device, for example, so as to deviate an evacuator of the air cleaner from the upper surface of the device, can support the protruding part and ensure the fixing of the subassembly at each of the first and second positions. 
     It is preferable that: the air cleaner has a cylindrical outer peripheral surface and is oriented so that the exhaust port of the air cleaner faces an opposite side to the engine; the pipe includes an end portion connected to the exhaust port, a return portion extending from the end portion toward an engine-side, and a downstream-side portion extending from a distal end of the returning portion to the engine side along the air cleaner; and the air cleaner is mounted on the seat plate so as to locate at least a part of the downstream-side portion in a space between the cylindrical outer peripheral surface of the air cleaner and the upper surface of the seat plate. The pipe, though including the returning portion, allows the pipe and the air cleaner to have a small width size, thereby enabling the subassembly and hence the device-assembly to be compact and enabling the installation of the device-assembly into the installation space to be facilitated. Moreover, utilizing the space, which is originally a dead space, as a part of a space for piping the downstream-side portion enhances a space-utilization efficiency. 
     For the configuration, the downstream-side portion of the pipe preferably has a substantially-triangle-shaped cross section including a hypotenuse portion at least a part of which is located in the space. The shape of the cross section allows the subassembly to have a further reduced size to make the size-reduction and the facilitation in the installation be more effective. 
     Specifically, the cross section of the downstream-side portion of the pipe is preferably shaped as a substantial right-angled triangle further including a vertical side portion to be opposed to the first structure. The shape of the cross section allows the total width size of the pipe and the air cleaner to be more reduced and thereby enables the downstream-side portion to be compactly arranged with no difficulty. 
     The pipe is, preferably, a molded product involving an integration of the returning portion and the straight-line portion with each other. The pipe thus formed as an integrally molded product (for example, a plastic injection molded product) allows the total width size of the pipe and the air cleaner to be small without difficulty, for example, as compared with a width size of a flexible hose bent in a U-shape. Furthermore, it is also possible to reduce a protrusion size of the returning portion in the air cleaner length direction, which is particularly advantageous when a space is also limited in the length direction of the air cleaner. 
     This application is based on Japanese Patent application No. 2013-239424 filed in Japan Patent Office on Nov. 20, 2013, the contents of which are hereby incorporated by reference. 
     Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention hereinafter defined, they should be construed as being included therein.