Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a straddle-type four wheeled all terrain vehicle, and more particularly to an intake structure of a cooling air for a straddle-type four wheeled all terrain vehicle in which a belt converter is mounted to an engine. 
     2. Description of the Related Art 
     In the straddle-type four wheeled all terrain vehicle, a belt converter is sometimes mounted to an engine. The belt converter is mounted between a crank shaft of the engine and a transmission to facilitate a speed change operation of a vehicle. 
     The belt converter is accommodated in a case. Since the belt converter generates heat by an operation thereof, an air is introduced from outside into the case, thereby cooling the belt converter to prevent an increase in temperature in the case. 
     An example of the intake structure of the cooling air into the belt converter is that a box-shaped space opened at a front and closed at a periphery thereof is provided in a lower portion of a tip end portion of a front fender and an air passage reaching the belt converter is opened in this space (see Japanese Patent No. 2963052). 
     However, in this structure, when the vehicle is traveling, foreign substances such as trash, mud, water as well as fresh air from front, sometimes enter the intake port. For this reason, there is a need for an improved intake structure of the cooling air into the belt converter. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the above-described problem, and an object of the present is to provide a straddle-type four wheeled all terrain vehicle having an intake structure of a cooling air into a belt converter that is capable of preventing the entry of foreign substances such as water and mud with a simple constitution. 
     According to the present invention, there is provided a straddle-type four wheeled all terrain vehicle comprising: a vehicle body; a straddle-type seat provided on an upper portion of the vehicle body; a bar-type handle having a steering shaft and provided forward of the seat; a vehicle body cover covering a portion of the vehicle body including the steering shaft from above, the steering shaft penetrating through the vehicle body cover; and a belt converter, wherein an opening of the vehicle body cover through which the steering shaft passes is an intake port of a cooling air into the belt converter. 
     With this constitution, since the intake port through which the cooling air is taken into the belt converter from outside is provided at the middle in the longitudinal direction of the vehicle body and at a high position of the vehicle body, the water, mud or the like hardly enters the intake port. Besides, since the opening of the vehicle body cover through which the steering shaft passes is utilized, the intake port can be structured very simply. Also, the intake port is formed around the steering shaft of the handle and just before the rider, and therefore, if the intake port is clogged with the foreign substances or the like, they can be immediately found and removed. 
     Preferably, in the straddle-type four wheeled all terrain vehicle, a relay chamber may be formed inside of the vehicle body cover such that the relay chamber communicates with the opening, and a cooling air intake port of the belt converter may be opened in the relay chamber. 
     Thereby, the cooling air intake passage from the opening of the vehicle body cover to the belt converter can be easily constituted. 
     Preferably, in the straddle-type four wheeled all terrain vehicle, a portion of the vehicle body cover around the opening may be raised to be formed into a swelled portion, and the relay chamber may be structured to have a chamber wall including one part constituted by a portion of the swelled portion including the opening and the other part through which the steering shaft and a cooling air intake duct having the cooling air inlet port of the belt converter that is opened in the relay chamber penetrate. 
     Thereby, the intake port through which the cooling air is taken into the belt converter can be formed at a high position because of the swelled portion. In addition, since the swelled portion is utilized as part of the chamber wall, the relay chamber can be easily constituted. 
     Preferably, in the straddle-type four wheeled all terrain vehicle, a portion of the other part of the chamber wall through which at least the steering shaft and the cooling air intake duct of the belt converter penetrate may be comprised of a flexible plate member. 
     Since the flexible plate member is flexible, steering shaft, the cooling air intake duct, or the like can be easily made to penetrate through the corresponding through holes even if some positional difference occurs between these members and the through holes. 
     Preferably, in the straddle-type four wheeled all terrain vehicle, the swelled portion may be configured such that front and side portions around the opening is raised and the swelled portion extends rearwardly, the relay chamber may be structured such that a portion of the swelled portion defines one part of the chamber wall of the relay chamber, a front wall member, a pair of side wall members, a flexible plate member, and a seal structure define the other part of the chamber wall, the front wall member and the pair of side wall members are downwardly protruded at a front end portion and side end portions of the swelled portion that is located forward and side of the opening in an inner face of the vehicle body cover such that the front wall member and the side wall members form an enclosure, the flexible plate member substantially defines a bottom and a rear of a space covered by the portion of the swelled portion that is located forward and side of the opening, the seal structure is formed between a front end of the flexible member and a lower end of the front wall member, and the steering shaft and the cooling air intake duct of the belt converter may penetrate through the flexible plate member. 
     With this constitution, a wide relay chamber can be formed. Besides, since the bottom wall and the rear wall of the relay chamber can be formed by one flexible member, its structure can be simplified. Further, since the seal structure is provided at the front lower portion of the relay chamber that tends to be splashed with mud or water, the entry of the mud, water, or the like into the relay chamber can be prevented. 
     Preferably, in the straddle-type four wheeled all terrain vehicle, the seal structure may be formed such that a support member being a frame member of the vehicle body extends along a lower end of the front wall member as having a clearance between the front wall member and the support member, a cushion member may be provided on the support member to fill the clearance, and a front end of the flexible plate member may be connected to the support member. 
     Thereby, the seal structure can be easily formed. 
    
    
     The above and further objects and features of the invention will be more fully apparent from the following detailed description with accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a left side view showing an entire configuration of a straddle-type four wheeled all terrain vehicle according to an embodiment of the present invention; 
     FIG. 2 is a front view showing the entire configuration of the straddle-type four wheeled all terrain vehicle according to the embodiment; 
     FIG. 3 is a plan view showing the entire configuration of the straddle-type four wheeled all terrain vehicle according to the embodiment; 
     FIG. 4 is a lateral perspective view of a vehicle body main part showing an intake passage of a belt converter and an air cleaner utilizing a relay chamber of FIGS. 1-3 and an engine coolant circulating passage; 
     FIG. 5 is a partially enlarged cross-sectional view showing a detailed structure of the relay chamber of FIGS. 1-3; 
     FIG. 6 is a cross-sectional view taken in the direction of the arrow VI—VI of FIG. 5; 
     FIG. 7 is a view taken from the direction of the arrow A of FIG. 5; and 
     FIG. 8 is a plan view showing a shape of a flexible plate member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to drawings. 
     FIG. 1 is a left side view showing an entire configuration of a straddle-type four wheeled all terrain vehicle according to an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a plan view thereof. 
     Referring now to FIGS. 1-3, a straddle-type four wheeled all terrain vehicle  1  comprises a steering bar handle  4  mounted to a vehicle body frame (partially shown in figures)  2 , right and left front wheels  8 , and right and left rear wheels  9 . The straddle-type four wheeled all terrain vehicle  1  further comprises a straddle-type seat  6  placed rearward of the handle  4  and apart a certain distance therefrom, and foot boards  10  provided on opposite sides forward and downward of the seat  6 , rearward of the handle  4 , and at positions substantially as high as an axle of the front wheels  8  and the rear wheels  9 . The vehicle  1  is provided with a V-type engine  11  between the right and left foot boards  10  such that a lower end of the engine  11  is substantially as high as the foot boards  10 . In the V-type engine  11 , two cylinders are respectively inclined forward and rearward. A carburetor  32  is provided between these inclined cylinders for supplying a fuel-air mixture to the respective cylinders. An air cleaner  21  is provided immediately above the carburetors  32  for cleaning an air used in the engine  11 . The air cleaner  21  is positioned between the handle  4  and the seat  6 . Thus, in this embodiment, a vehicle body structure in which the air cleaner  21  is placed between the handle  4  and the seat  6  is realized by using the V-type engine  11  and by inclining the two cylinders forward and rearward. 
     A front fender  35  is provided as generally covering a portion of the vehicle body that is located forward of the handle  4  from above. An air cleaner cover  5  and a side cover  34  are provided rearward of the front fender  35  such that these covers generally cover a portion of the vehicle body located between the handle  4  and the seat  6  from above. The air cleaner cover  5  covers a portion of the air cleaner  21  of the portion of the vehicle body located between the handle  4  and the seat  6  from above and the side cover  34  covers the other portion. A rear fender  81  is provided rearward of the side cover  34  such that it generally covers a portion of the vehicle body that is located rearward of the seat  6  other than the seat  6 . The front fender  35 , the air cleaner cover  5 , the side cover  34 , and the rear fender  81  compose the vehicle body cover  201 . A front carrier  51  is provided on the front fender  35  and a rear carrier  82  is provided on a rear portion of the rear fender  81 . An intake opening  102  is formed in a middle portion in the lateral direction of the vehicle body at a boundary portion between the front fender  35  and the side cover  34 , for introducing a fresh air into the engine or the like. A steering shaft  14  of the handle  4  passes through the intake opening  102 . A handle cover  16  provided on the handle  4  covers the intake opening  102  from above. 
     The front fender  35  extends substantially horizontally with a width gradually increased from its front end to its rear end. The front fender  35  is configured such that a front half portion of the intake opening  102  is formed in a middle portion of a rear end portion of the front fender  35  and a portion around the front half portion of the intake opening  102  is raised to be formed into a swelled portion  101  and right and left side portions of the rear end portion other than the swelled portion  101  extends downwardly. A front periphery and a side periphery of the front fender  35  are inwardly bent substantially at a right angle. The side cover  34  and the air cleaner cover  5  are entirely curved in the lateral direction of the vehicle body such that their central portions are ridge-shaped. The central ridge portions are substantially horizontal from the front end to the middle portion and downwardly inclined from the middle portion to the rear end in the longitudinal direction of the vehicle body. The air cleaner cover  5  is located on an opening formed at a top portion of the side cover  34 . A rear half portion of the intake opening  102  is formed in a middle portion of the front end portion of the side cover  34 , which is fitted to a rear end portion of the front fender  35 . A rear end portion of the side cover  34  is covered by the front end portion of the seat  6 , although this is not shown. In a portion of the vehicle body cover  201  that is comprised of the front fender  35 , the air cleaner cover  5 , and the side cover  34 , front and side portions around the intake opening  102  is raised from the upper surface of the front fender  35  to be formed into the swelled portion  101 , which substantially extends rearwardly over a certain length. By thus raising the portion around the intake opening  102 , the intake opening  102  can be made correspondingly higher. 
     A relay chamber  31  is structured such that a portion of the swelled portion  101  that is located forward and side of the intake opening  102  (hereinafter referred to as a swelled front portion)  101   a  defines one part of a chamber wall thereof and a member such as a flexible plate member  33  defines the other part of the chamber wall. The relay chamber  31  serves to relay the fresh air from the intake opening  102  to the engine or the like. By thus utilizing the swelled front portion  101   a  as part of the chamber wall of the relay chamber  31 , the relay chamber  31  can be easily formed. 
     A pair of plate-shaped inner covers  52  are provided in a middle portion of an inner space of the front fender  35  such that they extend in the longitudinal direction of the vehicle body over the whole length of the front fender  35  as being apart from each other and having a certain height. The inner covers  52  are inside covers of the front wheels  8  and constitute part of side walls of the relay chamber  31  as mentioned later. 
     FIG. 4 is a lateral perspective view of a vehicle body main part showing the air intake passage of the belt converter and the air cleaner utilizing the relay chamber of FIGS. 1-3 and an engine coolant circulating passage. 
     Referring to FIG. 4, a belt converter chamber (not shown) is provided on the right side of a crank chamber (not shown) of the engine  11  and covered by a belt converter cover  83 . A belt converter  54  is accommodated in the belt converter chamber. A belt converter air intake duct  55  is connected to a front end portion of the belt converter chamber. An exhaust duct (not shown) is connected to the belt converter chamber. The belt converter air intake duct  55  forwardly and upwardly extends from a portion connected to the belt converter chamber and is opened at a tip end thereof in the relay chamber  31 . An air cleaner intake duct  29  is connected to a lower portion of a front face of the air cleaner  21 . The air cleaner air intake duct  29  extends forwardly and upwardly from a portion connected to the air cleaner  21  and is opened at a tip end thereof in the relay chamber  31 . This constitution enables the belt converter  54  and the air cleaner  21  to take in the fresh air through the intake opening  102  provided at the highest position of the vehicle body through the relay chamber  31 . In this constitution, since the intake opening  102  of the vehicle body cover  201  through which the steering shaft  14  passes is utilized as the intake port through which the fresh air is taken into the belt converter  54  and the air cleaner  21 , the intake port can be simply constituted. Also, since it is not necessary to directly connect the belt converter intake duct  55  and the air cleaner intake duct  29  to the intake opening  102 , the fresh air intake passage from the intake opening  102  to the belt converter  54  and the air cleaner  21  can be easily constituted. 
     A radiator  56  is mounted substantially at the middle of the front end portion of the vehicle body in the vertical direction. A thermostat  85  is provided in the vicinity of a lower portion of the relay chamber  31 . A coolant hose  84  connects the radiator  56 , the thermostat  85 , and the engine  11 , thereby forming a circulating passage  202  of the engine coolant (hereinafter simply referred to as a coolant). A water pump  57  is provided on a left side portion of the lower portion of the engine  11 . An internal circulating passage (not shown) of the coolant is formed in the engine  11  such that it extends from a discharge port of the water pump  57  to an upper end portion of each cylinder of the engine  11 . Two branch hoses  84   a ,  84   b  of a discharge-side coolant hose  84   c  of the water pump  57  (hereinafter referred to as a discharge-side coolant hose) respectively extend forwardly and upwardly from an end of the internal circulating passage of the upper end portion of each cylinder to the thermostat  85 , where these hoses meet to be formed into the discharge-side coolant hose  84   c , which substantially horizontally extends to a position above and rearward of the radiator  56  and further forwardly and downwardly extends so as to be connected to an upper end of the radiator  56 . A suction-side coolant hose  84   d  rearwardly and downwardly extends from a lower end portion of the radiator  56  and is connected to a suction port of the water pump  57 . A coolant filler neck  58  is provided integrally with and adjacently to the thermostat  85  so as to communicate with the thermostat  85 , for filling the coolant into the coolant circulating passage  202 . The coolant filler neck  58  extends upwardly from the thermostat  58  and is opened at a tip end thereof in the relay chamber  31 . A cap  58   a  is attached to the coolant filler neck  58 . Thereby, the filling port of the coolant is positioned at the highest position of the coolant circulating passage  202  without lessening visual appearance. Also, with this constitution, since the discharge-side coolant hose  84   c  is put through the upper end of the radiator  56  obliquely from above, the air in the coolant circulating passage  202  can be easily released. It should be noted that the coolant filler neck  58  is provided with a coolant overflow pipe  59  mounted vertically downwardly from a side portion of the coolant filler neck  58 , for discharging the coolant overflowed from the coolant circulating passage  202 . 
     FIG. 5 is a partially enlarged cross-sectional view showing a detailed structure of the relay chamber of FIGS. 1-3. FIG. 6 is a cross-sectional view taken in the direction of the arrows substantially along line VI—VI of FIG.  5 . FIG. 7 is a view taken from the direction of the arrow A of FIG.  5 . FIG. 8 is a plan view showing a shape of a flexible plate member. In FIG. 5, a side wall portion of the relay chamber  31  is shown as being cut out. In FIG. 5, side wall ribs  65  and the inner covers  52  thus constituting the cut-out side wall portion are indicated by imaginary lines. 
     As shown in FIGS. 5-7, a plate-shaped front wall rib  64  is provided at a front end portion of the swelled front portion  101   a  in an inner face of the front fender  35  such that it extends downwardly to a predetermined vertical position and in the lateral direction of the vehicle body over substantially the entire width of the swelled front portion  101   a . A semi-circular cut-out portion  64   a  is formed at a portion located slightly leftward from the center of the lower end of the front wall rib  64 . A cross member  2   a  (support member) extends along the lower end of the front wall rib  64  as having a predetermined clearance below the front wall rib  64 . The cross member  2   a  constitutes part of the vehicle body frame  2  and an upper face thereof is flat. The discharge-side coolant hose  84   c  penetrates through the front wall rib  64  in the cut-out portion  64   a  in the longitudinal direction of the vehicle body. A cushion member  63  is provided to fill the clearance between the upper face of the cross member  2   a  and the front wall rib  64 , and the discharge-side coolant hose  84   c , and the clearance between the discharge-side coolant hose  84   c  and the front wall rib  64 . The cushion member  63  is, for example, made of sponge and comprised of a portion  63   a  provided on the cross member  2   a  and a portion  63   b  wound around the discharge-side coolant hose  84   c.    
     A pair of side wall ribs  65  are protruded at right and left side end portions of the swelled front portion  101   a  in the inner face of the front fender  35  such that these ribs extend in the longitudinal direction of the vehicle body. The inner covers  52  are respectively mounted to outer faces of the side wall ribs  65  to extend downwardly. 
     The side wall ribs  65  and the inner covers  52  cover a side of a space located below the space covered by the swelled front portion  101   a  over the entire height from the inner face of the front fender  35  to the upper face of the cross member  2   a . Therefore, the front wall rib  64 , and the side wall ribs  65  and the inner covers  52  form an enclosure at the front end portion and the opposite side end portions of the swelled front portion  101   a.    
     A flexible plate member  33  substantially defines the bottom and rear of the space covered by the swelled front portion  101   a , the front wall rib  64 , the side wall ribs  65  and the inner covers  52 . The flexible plate member  33  is, for example, comprised of a rubber plate. As shown in FIG. 8, the flexible plate member  33  is comprised of a rectangular bottom wall portion  33   a  and a substantially trapezoid rear wall portion  33   b  formed at the rear end thereof as having a width smaller than that of the bottom wall portion  33   a . The bottom wall portion  33   a  conforms in shape to the bottom of the space covered by the front wall rib  64 , the side wall ribs  65  and the inner covers  52 . A steering shaft through hole  72 , an intake duct through hole  73  for air cleaner, an intake duct through hole  74  for belt converter, and a coolant filler neck through hole  75  are formed in the bottom wall portion  33   a . Cuts  72   a  and cuts  74   a  are respectively formed in the steering shaft through hole  72  and the intake duct through hole  74 . These cuts make it easy that the corresponding members are inserted into the respective holes. A slit  76  is formed in the bottom wall portion  33   a  from the front end to the steering shaft through hole  72 . The slit  76  allows the steering shaft mounted to the vehicle to be put through the steering shaft through hole  72  when the flexible plate member  33  is mounted to the vehicle body. Elongated holes  77  are formed on opposite sides with respect to the slit  77 . The elongated holes  77  are used in such a manner that bands are put therethrough to allow the slit  76  to be tightened to prevent it from being widened after the steering shaft is put through the steering shaft hole  72 . A wide cut-out portion  33   c  is formed at a middle portion of a rear end of the rear wall portion  33   b . Small holes  71  are formed on opposite sides of the rear end portion of the rear wall portion  33   b.    
     As shown in FIG. 5, a front end portion of the bottom wall portion  33   a  of the flexible plate member  33  is placed on the upper face of the cross member  2   a  adjacently to the rear end of the cushion member  63 . The bottom wall portion  33   a  horizontally extends rearwardly from the portion fixed to the cross member  2   a  to the rear end of the front fender  35 , from where the rear wall potion  33   b  upwardly and inwardly extends. FIG. 8 illustrates a boundary  33   d  between the bottom wall portion  33   a  and the rear wall portion  33   b , at which the flexible plate member  33  is bent. As shown in FIG. 7, rear peripheral portions of the front fender  35  are inwardly bent at a right angle to be formed into rear peripheral ribs  35   b  and resin rivets  66  are formed at predetermined portions of outer faces of the rear peripheral ribs  35   b . As shown in FIGS. 5,  7 , the rear wall portion  33   b  of the flexible plate member  33  passes through between the right and left rear peripheral ribs  35   b  to the outer face side thereof, from where the rear wall portion  33   b  upwardly and forwardly extends along the outer face of the rear peripheral ribs  35   b  to a vicinity of the intake opening  102 . In the vicinity of the opening  102 , the resin rivets  66  are inserted through the small holes  71  and with these rivets, the rear wall portion  33   b  can be secured to the rear peripheral ribs  35   b . The cut-out portion  33   c  of the rear wall portion  33   b  serves to prevent interference with the rearwadly inclined steering shaft  14 . 
     As shown in FIGS. 5,  6 ,  8 , in this embodiment, the coolant hoses  84   a ,  84   b ,  84   c , the thermostat  85 , and the coolant overflow pipe  59  are placed in part of the space surrounded by the front wall rib  64  and the side wall ribs  65 , and the inner covers  52 . The bottom wall portion  33   a  of the flexible plate member  33  cover these members such that these members are located outside of the relay chamber  31 . Therefore, the bottom wall portion  33   a  is configured to have a swelled portion  33   e  located at substantially the center in the lateral direction thereof that is slightly leftward when seen in a front view and substantially at a front half thereof when seen in a side view. 
     The steering shaft  14 , the air cleaner intake duct  29 , the intake duct  55  for belt converter, and the coolant injecting tube  58  respectively penetrate through the bottom wall portion  33   a  in the holes  72 ,  73 ,  74 ,  75 . By using the flexible plate member  33  as the portions of the chamber wall of the relay chamber  31  through which the members  14 ,  29 ,  55 ,  58  such as the steering shaft or the like penetrates, these members can be easily made to penetrate through the through holes even if some positional difference occurs between the members  14 ,  29 ,  55 ,  58  and the through holes  72 ,  73 ,  74 ,  75 . 
     A coolant supply opening  61  is formed in a portion of the swelled front portion  101   a  of the front fender  35  that is located above the filler neck  58 , and a lid member  62  is removably fitted to the coolant supply port  61  (see FIGS. 2,  3 ). 
     Thus, the swelled front portion  101   a , the front wall rib  64 , the cushion member  63 , the cross member  2   a , the side wall ribs  65 , the inner covers  52 , and the flexible plate member  33  constitute the chamber wall of the relay chamber  31 . This constitution provides the wide relay chamber  31 . Besides, since the bottom wall and the rear wall of the relay camber  31  are constituted by one flexible plate member  33 , the structure can be simplified. 
     Subsequently, how so constituted straddle-type four wheeled all terrain vehicle operates and is used will be explained. 
     Referring to FIGS. 1-5, when the rider starts the straddle-type four wheeled all terrain vehicle  1  and the engine  11  operates, the belt converter  54  is activated, thereby causing the fresh air to be taken into the belt converter chamber through the clearance between the intake opening  102  and the steering shaft  14 , the relay chamber  31 , and the belt converter intake duct  55 . The belt converter  54  is cooled by the fresh air. Meanwhile, the fresh air to be used in the engine  11  is taken into the air cleaner  21  through the clearance between the intake opening  102  and the steering shaft  14 , the relay chamber  31 , and the air cleaner intake duct  29  and purified therein to be supplied to the engine  11  through the carburetor  32 . While the straddle-type four wheeled all terrain vehicle  1  is traveling, foreign substances such as water or mud sometimes might fly from front of the vehicle. However, since the front portion of the relay chamber  31  is closed and the intake opening  102  as the intake port of the fresh air is provided at the central portion in the longitudinal direction of the vehicle body and at a high position of the vehicle body, the foreign substances such as water or mud hardly enters the intake opening  102 . In addition, since the intake opening is formed around the steering shaft  14  of the handle  4  and located just before the rider. Therefore, if the intake opening  102  is clogged with the foreign substances, they can be found immediately and removed. In some cases, the water, mud or the like splashes up from below of the vehicle body. In such cases, the mud or water tends to splash up to the front lower corner portion of the relay chamber  31 , but since a seal structure comprised of the cushion member  63  and the cross member  2   a  is formed in this portion, the entry of the water or mud into the relay chamber  31  can be prevented. 
     Meanwhile, when the engine  11  starts, the coolant circulates through the circulating passage  202  to cool the engine  11 . By opening/closing the control valve of the thermostat  85 , the circulation of the coolant is released or stopped. When the temperature of the coolant is increased to a certain value or more and an internal pressure is increased to cause the coolant to be overflowed, the overflowed coolant is discharged from the coolant overflow pipe  59  to a reserve tank (not shown). When the coolant is changed or the amount of the coolant is checked, the rider opens the lid member  62  of the front fender  35  and detaches the cap  58   a  to fill the coolant from the upper end of the coolant filler neck  58 . In this case, since the coolant filler neck is located at the highest point of the coolant circulating path  202 , the coolant can be injected while easily releasing the air. 
     Alternatively, the relay chamber  31  of this embodiment may be omitted. 
     Also, the swelled portion  101  formed around the intake opening  102  may be dispensed with. 
     While the swelled portion  101  substantially extends to a position rearward of the opening, this may be formed only around the portion of the intake opening  102 . 
     While the relay chamber  31  extends to the below of the swelled front portion  101   a , this may be formed in one part of the swelled front portion  101   a.    
     While most of the bottom wall and the rear wall of the relay chamber  31  may be constituted by the flexible plate member  33 , only the portion of the chamber wall through which the other members penetrate may be constituted by the flexible plate member  33 . For example, only the bottom wall portion of the chamber wall may be constituted by the flexible plate member  33 . 
     Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, the description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and/or function may be varied substantially without departing from the spirit of the invention and all modifications which come within the scope of the appended claims are reserved.

Technology Category: 4