Abstract:
A fuel system for a work vehicle including a fuel tank comprising a main tank body and an auxiliary tank body, a canister, and a fuel-gas introducing passage for connecting a top portion of the auxiliary tank body to the canister. The top portion of the auxiliary tank body is located higher than the main tank body when the fuel tank is installed on the work vehicle. A fuel filling pipe extends through the top portion of the auxiliary tank body and has a first end arranged outside the auxiliary tank body and a second end arranged within the auxiliary tank body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application is a U.S. continuation of U.S. patent application Ser. No. 13/423,551 filed Mar. 19, 2012, the disclosure of U.S. patent application Ser. No. 13/423,551 is hereby expressly incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]    The present invention relates to a work vehicle including an engine and a fuel system mounted in a rear area of a vehicle frame extending between a right and left rear wheels rearwardly of a driver&#39;s seat. 
       BACKGROUND ART  
       [0003]    U.S. Patent Application Publication No. US 2010/0242924 discloses a lawn mower including a rear frame formed of a right and left pair of side members made of sheet metal and a mounting surface supported rearwardly of the right and left side members, for example. An air-cooled engine is mounted on the mounting surface with an output shaft thereof projecting forward of a vehicle body. A muffler is disposed in a transverse position rearwardly of the engine. Fuel tanks are provided above the right and left rear wheels, respectively, to act as a fuel system. Evaporated gas separator tanks and canisters are disposed between the fuel tanks and the engine to allow fuel gas evaporated within the fuel tanks to combust in the engine. Each of the evaporated gas separator tanks is configured to recover fuel gas having evaporated within the fuel tank and direct it to the canister, and is disposed in a gas passageway between each fuel tank and each canister. The canisters are provided under the right and left fuel tanks in association with the right and left fuel tanks, respectively, to be distributed in the right and left sides of a rear portion of an oil cooler in a cooling air passageway at positions that are spaced from each other substantially equidistantly from a lateral center line of a traveling vehicle body. In such a conventional fuel system, it is required to provide long hoses for connecting between the fuel tanks, canisters and engine, which results in a complicated hose arrangement. 
         [0004]    Further, U.S. Pat. No. 7,849,837 B2 discloses a lawn mower provided with a fuel system for performing evaporated fuel processing. Type of lawn mower includes a fuel tank disposed on a side of an engine mounted rearwardly of a vehicle frame, and a battery unit fixed to the vehicle frame rearwardly of the engine. On the fuel tank is mounted a canister communicating with an upper inner space of the fuel tank. The canister has a purge conduit extending from the opposite side of a port communicating with the fuel tank and fixed to a purge joint at a lower end thereof. In this arrangement, the canister is provided above the fuel tank, which inevitably limits a space for accommodating the canister. As a result, restrictions may be imposed in the size as well as the maintenance and inspection of the canister. 
       SUMMARY OF INVENTION  
       [0005]    The object of the present invention is to provide a work vehicle in which an engine and a fuel system are properly arranged for improving effective use of space and achieving simplification of the maintenance and inspection. 
         [0006]    In order to achieve the above-noted object, a work vehicle according to the present invention comprises a vehicle frame extending between a right and left pair of rear wheels; a horizontal mounting surface defined in the vehicle frame in a peripheral area of the rear wheels; an engine arranged on the mounting surface at a central portion thereof in a transverse direction of the vehicle; a fuel tank including a main tank body mounted under a driver&#39;s seat and an auxiliary tank body mounted on one lateral side of the engine in the transverse direction of the vehicle; and a canister mounted on the mounting surface adjacent to the engine on one lateral side of the engine and rearwardly of and adjacent to the auxiliary fuel tank. 
         [0007]    With the above-noted arrangement, the fuel tank is divided into the main tank body and the auxiliary tank body that are provided spacious areas, respectively, such as under the driver&#39;s seat and the side of the engine, as a result of which good efficiency of spatial use can be achieved. Further, the fuel tank, vertical engine and canister are adjacently provided so that they do not substantially overlap each other as viewed from the top. Since the particularly heavy engine is provided vertically in the central portion in the transverse direction of the vehicle, the stability of the work vehicle is secured. Further, the engine, fuel tank and canister are adjacently disposed, which can diminish a piping layout extending between those devices. In addition, the fuel tank is divided into the main tank body mounted under the driver&#39;s seat and the auxiliary tank body mounted adjacent to the fuel tank and the canister to effectively use the space, which provides a large capacity for the fuel tank. 
         [0008]    In a preferred embodiment, at least a large part of the main tank body is covered by the driver&#39;s seat, thereby to protect the main tank portion. Further, the auxiliary tank portion is allowed to extend upwardly from a side of the driver&#39;s seat, which improves the oil-feeding performance. 
         [0009]    When a battery unit is provided rearwardly of the canister in view of the size of the canister smaller than the engine, the canister and the battery unit are longitudinally arranged, which further miniaturizes the construction. 
         [0010]    In addition, a muffler is mounted on the other lateral side of the engine, that is a side of the vehicle, which enhances thermal isolation and cooling properties of the muffler. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
         [0011]    In the drawings, there is illustrated the following. 
           [0012]      FIG. 1  is a perspective view from an upper diagonal direction of a work vehicle according to the present invention showing a basic arrangement of an engine and a fuel system mounted in a rear area of the vehicle; 
           [0013]      FIG. 2  is a top plan view of the basic arrangement of the engine and the fuel system mounted in the rear area of the vehicle; 
           [0014]      FIG. 3  is a perspective of a lawn mower exemplifying the work vehicle according to the present invention; 
           [0015]      FIG. 4  is a side view of the lawn mower in  FIG. 3 ; 
           [0016]      FIG. 5  is a top plan view of the lawn mower in  FIG. 3 ; 
           [0017]      FIG. 6  is a perspective view of the fuel tank; 
           [0018]      FIG. 7  is a sectional view of an auxiliary tank body of the fuel tank; 
           [0019]      FIG. 8  is a top plan view showing a mounting structure of the fuel tank; 
           [0020]      FIG. 9  is a schematic view showing a power transmission system. 
           [0021]      FIG. 10  is a perspective view of a lawn mower according to a modified embodiment of the present invention; 
           [0022]      FIG. 11  is a perspective view showing a mounting structure of the fuel tank according to a further modified embodiment of the present invention; 
           [0023]      FIG. 12  is a perspective view of the fuel tank according to the further modified embodiment of the present invention; and 
           [0024]      FIG. 13  is a perspective view of the auxiliary tank body of the fuel tank according to the further modified embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS  
       [0025]    Prior to describing specific embodiments of a work vehicle according to the present invention, a basic arrangement of an engine and a fuel system mounted in a rear area of the vehicle will be described first in reference to schematic views shown in  FIGS. 1 and 2 . 
         [0026]    In the rear area of the vehicle are included a right and left pair of rear wheels  3   b  and a rear frame  11  acting as a vehicle frame extending between the rear wheels  3   b.  A driver&#39;s seat  50  is arranged slightly forwardly of a center of an axle of the rear wheels, which is only partially depicted in two-dot chain line to provide good visibility for other devices. 
         [0027]    A substantially horizontal mounting surface  12  is defined in the rear frame  11  in a peripheral area of the rear wheels  3   b,  which is formed of a floor material mounted on the rear frame  11  in this example. The engine  20  is mounted in a vertical position, with an output shaft thereof being directed downward, on the mounting surface  12  in a central portion of a transverse direction of the vehicle, rearwardly of the center of the axle of the rear wheels  3   b.  A fuel tank  40  is arranged forwardly of and adjacent to the engine  20 . 
         [0028]    The fuel tank  40  includes a main tank body  41  mounted under the driver&#39;s seat  50 , and an auxiliary tank body  42  mounted on one lateral side, on the right side in the illustrated example, of the engine  20  in the transverse direction of the vehicle. The main tank body  41  has a rectangular shape with substantially the same width as the driver&#39;s seat  50  and a length greater than that of the driver&#39;s seat  50  to provide a large capacity in spite of its small depth to effectively use a space under the driver&#39;s seat  50  limited vertically. The auxiliary tank body  42  communicates with the main fuel tank  41 , extending vertically on a lateral side area of the engine  20  rearwardly of the driver&#39;s seat  50 . A cylindrical oil-feeding unit  44  is provided in a top portion of the auxiliary tank body  42  with a fuel cap. 
         [0029]    A canister  45  is mounted on the mounting surface  12  adjacent to the engine  20  on one lateral side (the right side in this example) of the engine  20  and rearwardly of and adjacent to the auxiliary fuel tank  43 . A canister connecting port  42   b  is provided in the top portion of the auxiliary tank body  42  to be connected to the canister  45  through a tube or hose. Although not shown, the canister  45  is also connected to an air intake system of the engine  20  through a tube or hose. Since the engine  20 , auxiliary tank body  42  and canister  45  are adjacently arranged so that they do not overlap as viewed from the top, the tubes or hoses for connecting those devices may be shortened, which results in a compact piping layout. 
         [0030]    Apart from the above-noted engine  20 , auxiliary tank body  42  and canister  45 , on the mounting surface  12  are mounted a muffler  21  on the other lateral side, the left side in this example, of the engine  20 , and a battery unit  91  directly rearwardly of the canister  45 . A bent, outer pipe frame  14  having a C-shape as viewed from the top is mounted to surround those devices above the mounting surface  12 . The outer pipe frame  14  is connected at opposite ends thereof to right and left vertical frames  13  extending upwardly from the rear frame  11  rearwardly of the driver&#39;s seat  50 . Control cables are housed in an inner space of the outer pipe frame  14 . The control cables include a cable for adjusting rotational speed of the engine  20 , for example. 
         [0031]    A partition  16  is preferably provided to separate between an engine area and a driver&#39;s area in a longitudinal direction of the vehicle in order to prevent heated air from blowing directly into the driver&#39;s seat  50 . Since the fuel tank  40  divided into the main tank body  41  and auxiliary tank body  42  extends over a boundary between the engine area and driver&#39;s area, it is preferable to allow the partition  16  to act as a retaining member to hold down the fuel tank  40  from above. 
         [0032]    The specific embodiments of the present invention will be described hereinafter in reference to the accompanying drawings. As shown in  FIGS. 3 and 5 , the work vehicle according to the present invention is represented by a ride-on lawn mower including a vehicle body  1  supported to a right and left pair of front wheels  3   a  and a right and left pair of rear wheels  3   b.  This type of ride-on lawn mower is also referred to as a zero-radius-turning mower, in which the right and left rear wheels  2   b  are independently controlled in forward/reverse drive speed.  FIG. 3  is a diagonal rear perspective view of the ride-on lawn mower,  FIG. 4  is an overall side view thereof, and  FIG. 5  is an overall top plan view thereof. 
         [0033]    The vehicle body  1  includes a front frame  10  and a rear frame  11  made of square pipe material, for example, as main components. A mower unit  8  is suspended from the front frame  10  between the right and left pair of front wheels  3   a  and the right and left pair of rear wheels  3   b  to be vertically movable through an unillustrated link mechanism. The link mechanism functions to vertically move the mower unit  8  in a horizontal position through pedal control and lever control. 
         [0034]    A boarding platform  51  made of sheet metal is provided to substantially cover the entire front frame  10  from above. The boarding platform  51  has a forwardly inclined surface formed by bending a front portion of the platform, and a horizontal surface continued from the inclined surface. A rubber mat  51   a  is laid over the horizontal surface, and a brake pedal  52  urged to return to a non-braking position is arranged in a central portion of the inclined surface. A driver&#39;s seat  50  is positioned one level higher rearwardly of the boarding platform  51 . Fenders  53  and handle units  6  having shift levers  60  are provided in lateral opposite sides of the driver&#39;s seat  50 , respectively. Various control levers and control buttons are arranged on a top surface of each fender  53 . A gate-shaped ROPS frame  15  vertically extends rearwardly of the driver&#39;s seat  50 . The ROPS frame  15  is made of square pipe material and is longitudinally bendable about a transverse axis at intermediate portions of right and left ROPS struts  15   a.  More particularly, the ROPS frame  15  is switchable between an upright standing position and a rearward lying position. In this type of ride-on lawn mower, a front area forwardly of the ROPS frame  15  of the vehicle body  1  is defined as a driver&#39;s section  5 , while a rear area rearwardly of the ROPS frame  15  of the vehicle body  1  is defined as a drive section  2 . 
         [0035]    The rear frame  11  has an arched shape as viewed from the top with a right and left pair of straight frame portions  11   a  extending longitudinally in the vicinity of the rear wheels  3   b  and a curved frame portion  11   b  projecting rearward for connecting the right and left straight frame portions  11   a  to each other. A substantially horizontal mounting surface  12  for receiving various devices constituting the drive section  2  is defined on the arched rear frame  11  rearwardly of the driver&#39;s seat  50 , which is formed as a top surface of a floor material mounted on the rear frame  11  in the current embodiment. Vertical frames  13  extend from an upper portion of the rear frame  11  to be spaced from each other by a predetermined interval. An outer pipe frame  14  having a similar shape to the contour of the rear frame  11  is attached to upper portions of the vertical frames  13 . 
         [0036]    In the central part of the mounting surface  12  is mounted a gas engine  20  with an output shaft thereof projecting downward. A fuel tank  40  is mounted over a region from a front area to a right-side area of the engine  20 . As shown in  FIGS. 6 to 8 , the fuel tank  40  consists of a main tank body  41  mounted under the driver&#39;s seat  50  forwardly of the engine  20 , an auxiliary tank body  42  extending vertically on the right side of the engine  20  rearwardly of the driver&#39;s seat  50 , and a neck-like transitional portion  43  connecting the main tank body  41  to the auxiliary tank body  42 . The main tank body  41  has a flat top surface and thus can be arranged efficiently along a lower surface of the driver&#39;s seat  50 . The auxiliary tank body  42  has a rectangular section elongated transversely of the vehicle body as viewed from the top and extends higher than the main tank body  41  with a top portion  42   a  thereof positioned at a level beyond the outer pipe frame  14 . An oil-feeding unit  44  is provided in a portion of the top portion  42   a  transversely outward of the vehicle body, while a canister connecting port  42   b  is provided in a portion of the top portion  42   a  transversely inward of the vehicle body (on the side adjacent to the engine). The oil-feeding unit  44  consists of an oil-feeding pipe  44   b  inserted into a hole formed in a top surface of the top portion  42   a,  and a fuel cap  44   a  attached to a distal end of the oil-feeding pipe  44   b.  As understood from  FIG. 7  representing a sectional view taken on line H-H of  FIG. 6 , the oil-feeding pipe  44   b  has a lower end positioned above a maximum height of the main tank body  41 . Since the canister connecting port  42   b  is provided substantially the highest position of the top surface of the top portion  42   a,  an upper space of the auxiliary tank body  42  including the oil-feeding pipe  44   b  is an air layer. Pressure in the air layer is maintained in a predetermined range by a two-way valve  48  disposed in a fuel gas conduit (hose)  46  extending from the canister connecting port  42   b.  Thus, the air layer is maintained regardless of regular change of the position of the vehicle body, which prevents a fuel from entering the canister connecting port  42   b.    
         [0037]    A canister  45  is placed on the mounting surface  12  adjacent to a rear side of the auxiliary tank body  42 . The canister  45  is connected to an air intake system of the engine  20  through a purge conduit (hose)  47 , and is connected to the canister connecting port  42   b  through a fuel gas conduit (hose)  46 . As the two-way valve  48  is disposed in the fuel gas conduit  46 , an air layer is secured above the auxiliary tank body  42  when a fuel is supplied, and pressure regulation is performed through the canister  45  when internal pressure of the tank is increased, or decreased with use of the fuel. 
         [0038]    In addition, a battery unit  91  is placed on the mounting surface  12  adjacent to a rear side of the canister  45  (see  FIG. 2 ). Further, a muffler  21  is placed on the mounting surface  12  on the opposite side of the battery unit  91  across the engine  20 , that is, on the left side of the engine  20 . A side portion of the muffler  21  faces an opening formed between the vertical frames  13 , and thus can be effectively cooled. An air cleaner  22  is mounted in a position higher than the engine  20  on the left side of the engine  20 . An engine cooling fan is provided above the engine  20  to be rotatable in unison with the output shaft  20   a  of the engine  20 , which is hidden in the drawings by an air-introducing housing for covering the engine cooling fan from above. 
         [0039]    In association with each of the right and left rear wheels  3   b,  an HST (hydrostatic transmission)  30  and a gear transmission mechanism  31  for transmitting drive power to the rear wheel  3   b  are provided as shown in  FIG. 9 . A propelling-line belt transmission mechanism  32  includes pulleys mounted between the output shaft  20   a  of the engine and the respective HSTs  30  so that output from the engine is transmitted to each HST. A shift control shaft for each HST (not shown) is linked to an associated shift lever  60  through a control link mechanism so that shifting operation is performed in response to longitudinal oscillating movement of each of the shift levers  60  mounted directly forwardly and laterally of the driver&#39;s seat  50  (see  FIG. 5 ). 
         [0040]    With the above arrangement, either of the right and left shift levers  60  is oscillated longitudinally to shift the HST  30  associated with the oscillated shift lever  60 , which allows the right and left rear wheels  3   b  to be independently speed changed. More particularly, in this type of ride-on lawn mower, the right and left front wheels  3   a  are followably steered while the right and left rear wheels  3   b  are independently driven for speed change, thereby to desirably produce a stop state for stopping the right and left rear wheels  3   b,  a straight-forward traveling state for driving the right and left rear wheels  3   b  forwardly or reversely at the same speed, a gentle-turn state for driving the right and left wheels  3   b  forwardly or reversely at different speeds, a pivot-turn state for stopping one of the right and left rear wheels  3   b  while driving the other of them forwardly or reversely, and a spin-turn state for driving one of the right and left rear wheels  3   b  forwardly while driving the other of them reversely. 
         [0041]    The mower unit  8  is suspended from the front frame  10  between the right and left pair of front wheels  3   a  and the right and left pair of rear wheels  3   b  to be vertically movable through the link mechanism  80 . The mower unit  8  includes three blades  83  arranged in the transverse direction of the vehicle body within a mower deck  81 . Each of the blades  83  is fixed to a drive shaft  83   a  supported to the mower deck  81 . A mower-unit belt transmission mechanism  82  is provided to include pulleys mounted on the output shaft  20   a  of the engine  20  and each drive shaft  83   a,  in which output from the engine  20  is transmitted to the mower unit  8 . As understood well from  FIG. 9 , the propelling-line belt transmission mechanism  32  and the mower-unit belt transmission mechanism  82  use the output shaft  20   a  of the engine  20  as an input shaft, and arranged at different levels independently of each other planarly. This arrangement allows constant-speed drive power to be transmitted to the mower unit  8  regardless of a traveling speed or traveling state. 
         [0042]    The fuel tank  40  is positioned under the driver&#39;s seat  50  without any mounting bracket to be fixed to the vehicle body. As shown in  FIG. 8 , the fuel tank  40  is mounted on a cross plate mounted on the rear frame  11  through an elastic member such as rubber and laterally positioned through a projecting elastic member attached to the rear frame  11 . The main tank body  41  has a forward portion held down by a coupling plate for connecting the right and left fenders  53  to each other, and a rearward portion, more particularly, a region around the transitional area  43 , held down by a plate-like retaining member  16  from above. The retaining member  16  is configured to section between an engine area and a driver&#39;s area in the longitudinal direction of the vehicle body to also act as a partition in order to prevent heated air from the engine  20  from blowing into directly to the driver&#39;s seat  50 . Thus, the retaining member (partition)  16  has a transverse dimension and a vertical dimension (height) over the entire width of the vehicle body and is fixed at opposite ends thereof to proximal end portions of the ROPS struts  15   a.  A tongue-like piece  16   a  bent horizontally is provided in a central lower end of the retaining member  16  to fit into a recess formed in the transitional portion  43  between the main tank body  41  and the auxiliary tank body  42 , thereby to hold down the fuel tank  40 . 
         [0043]    Various levers and switches are provided in the top surfaces of the fenders  53  positioned laterally of the driver&#39;s seat  50 . As apparent from  FIGS. 3 to 5  showing an external appearance of the vehicle, this type of ride-on mower does not include a hood for covering the engine area. Naturally, such a hood may be provided. 
       Modified Embodiments  
       [0044]    (1) In the first embodiment, the muffler  21  is placed on the side of the engine  20  along the longitudinal direction of the vehicle body. Instead, as shown in a modification of the ride-on lawn mower in  FIG. 10 , the muffler  21  may be placed rearwardly of the engine  20  along the transverse direction of the vehicle body. 
         [0045]    (2) In the first embodiment, the fuel tank  40  is held down from above by the retaining member  16  acting also as the partition extending transversely of the vehicle body. Instead, the partition and retaining member  16  may be separately provided. As shown in  FIG. 10 , for example, the main tank body  41  may be held down from above by a rod-like retaining member  16 A extending between cross members mounted forwardly and rearwardly of the main tank body  41 . In that case, the cross member mounted rearwardly of the main tank body  41  may act as a partition  16 B. 
         [0046]    (3) The fuel tank  40  shown as being mounted on the vehicle body in  FIG. 11  while shown solely in  FIG. 12  has a slightly different construction than that in the first embodiment. While the fuel tank  40  consists of the main tank body  41 , auxiliary tank body  42  and transitional portion  43  in the same way as the first embodiment, the transitional portion  43  extends upward to incline outwardly in the transverse direction of the vehicle body in order to position the auxiliary tank body  42  farther outwardly in the transverse direction of the vehicle body. In this modified mode as well, the oil-feeding unit  44  and canister connecting port  42   b  are provided in the top portion  42   a  of the auxiliary tank body  42  that is positioned at a level far higher than the main tank body  41 . The oil-feeding unit  44  according to the modified embodiment also consists of the oil-feeding pipe  44   b  inserted into the hole formed in the top surface of the top portion  42   a,  and the fuel cap  44   a  attached to the distal end of the oil-feeding pipe  44   b.  As understood from  FIG. 13 , the oil-feeding pipe  44   b  has the lower end positioned above a maximum height of the transitional portion  43  extending upwardly further from the main tank body  41 . In addition, since the canister connecting port  42   b  is provided substantially the highest position of the top surface of the top portion  42   a,  an upper space of the auxiliary tank body  42  including the oil-feeding pipe  44   b  is an air layer. In this modified embodiment as well, pressure in the air layer is maintained in a predetermined range by the two-way valve  48  disposed in the fuel gas conduit (hose)  46  extending from the canister connecting port  42   b.  Thus, the air layer is maintained regardless of regular change of the position of the vehicle body, which prevents the fuel from entering the canister connecting port  42   b.  As a result, the fuel enters the canister  45  less easily even in the sloping ground. 
         [0047]    (4) In the first embodiment, the present invention is applied to a mid-mount lawn mower. Instead, the present invention is also applicable to a front-mount lawn mower or work vehicles other than the lawn mower. 
       INDUSTRIAL USABILITY  
       [0048]    The present invention is applicable to a work vehicle with an engine and a fuel system mounted rearwardly.