Patent Publication Number: US-2007095324-A1

Title: Vehicular air cleaner structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2005-315063 filed on Oct. 28, 2005 the entire contents of which are hereby incorporated by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an improved structure of a vehicular air cleaner.  
      2. Description of Background Art  
      A known example of a vehicular air cleaner structure includes an intake pipe, which draws air into an air cleaner case, and a connection pipe, which connects the air cleaner case to a carburetor with both being connected to the air cleaner case. See, for example, Japanese Patent Laid-open No. 2004-270559.  
      Referring to  FIG. 3  of Japanese Patent Laid-open No. 2004-270559, an air cleaner case  53  has a single side wall that includes an intake pipe connection portion  61  that connects an intake pipe  51  and a connection pipe through hole  63  that supports a connection pipe  54  by letting it pass therethrough.  
      Referring to  FIG. 1 , the intake pipe  51  extends from a point downward of a front end of a seat  35  to the air cleaner case  53  disposed downward of the seat  35  at a center thereof.  
      The intake pipe  51  has a large air flow resistance because of its longer overall length. A filter disposed inside the air cleaner case  53  also has a large air flow resistance. When a throttle valve is suddenly opened during, for example, acceleration of a vehicle or the like, it becomes harder for the air to enter the air cleaner case  53  via the intake pipe  51 . As a result, there is a drop in pressure in the air cleaner case  53 . This impedes a good flow of air from an inside of the air cleaner case  53  toward the side of an engine. There is therefore a need for an improved response to an increase in an engine speed, that is, a throttle response by suppressing a drop in pressure inside the air cleaner case  53 .  
      There is also a need for improving assemblability of the intake pipe  51  and the connection pipe  54  for an improved productivity, when the intake pipe  51  and the connection pipe  54  are connected to the intake pipe connection portion  61  and the connection pipe through hole  63 , respectively, disposed in the side wall of the air cleaner case  53 .  
     SUMMARY AND OBJECTS OF THE INVENTION  
      It is therefore an object of the present invention to improve vehicular throttle response and productivity of air cleaners.  
      According to a first aspect of the present invention, there is provided an air cleaner structure for a vehicle. The structure includes an air cleaner disposed on a vehicle body frame. Further, the air cleaner includes an intake duct for drawing air in the air cleaner and a connecting tube for providing communication between the air cleaner and an engine side. The intake duct and the connecting tube are connected to the air cleaner.  
      The air cleaner structure according to a first embodiment of the present invention provides an air cleaner that includes an elastic body capable of being flexed by a change in pressure in the air cleaner. The elastic body is disposed on at least one of walls of the air cleaner.  
      An example of the effects achieved by a first embodiment of the present invention is, if the pressure inside the air cleaner is dropped when a throttle valve of an intake system is suddenly opened, the elastic body flexes into the air cleaner, thereby suppressing a substantial drop in pressure. Accordingly, air flows smoothly from the air cleaner to the engine side with a substantially little delay after the throttle valve is opened.  
      According to a second embodiment of the present invention, the intake duct and the connecting tube are supported by a single elastic body.  
      As an example of effects, the elastic body can be quickly and easily assembled to the air cleaner, as compared with an arrangement, in which an elastic body is provided separately for each of the intake duct and the connecting tube.  
      According to a third embodiment of the present invention, the vehicle includes a temperature sensor disposed on the air cleaner. The temperature sensor measures a temperature of air drawn into the air cleaner and the temperature sensor is supported by the elastic body.  
      As an example of effects, the elastic body can be quickly and easily assembled to the air cleaner as compared with an arrangement, in which another elastic body supporting the temperature sensor is assembled to the air cleaner.  
      According to a fourth embodiment of the present invention, the elastic body includes an elastic surface other than a support portion supporting the intake duct, the connecting tube, and the temperature sensor.  
      As an example of effects, a drop in pressure in the air cleaner is suppressed by the elastic surface other than the support portion supporting the intake duct, the connecting tube, and the temperature sensor.  
      According to the first embodiment of the present invention, the elastic body that is capable of being flexed by a change in pressure inside the air cleaner is disposed on at least one of the walls of the air cleaner. As a result, the elastic body suppresses an instantaneous pressure drop in the air cleaner when the throttle valve is suddenly opened. Air can thereby be drawn into the engine quickly and throttle response can be improved.  
      According to the second embodiment of the present invention, the intake duct and the connecting tube are supported by a single elastic body. The elastic body supporting the intake duct and the connecting tube can therefore be mounted at the same time. Assemblability can therefore be improved and productivity enhanced.  
      According to the third embodiment of the present invention, the vehicle includes the temperature sensor that measures the intake air temperature of the air cleaner and the temperature sensor is supported by the elastic body. This improves assemblability of the temperature sensor relative to the air cleaner and prevents vibration from being transmitted to the temperature sensor. Further, the elastic body can serve also as a sealing member for a mounting portion of the temperature sensor.  
      According to the fourth embodiment of the present invention, the elastic body includes the elastic surface other than the support portion supporting the intake duct, the connecting tube, and the temperature sensor. Thus, a drop in pressure in the air cleaner can be reliably suppressed by the elastic surface other than the support portion.  
      Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:  
       FIG. 1  is a side elevational view showing a vehicle that adopts an air cleaner structure according to an embodiment of the present invention;  
       FIG. 2  is a plan view showing the vehicle according to the embodiment of the present invention;  
       FIG. 3  is a principal plan view illustrating an intake system according to the embodiment of the present invention;  
       FIG. 4  is a perspective view showing an air cleaner and an intake duct according to the embodiment of the present invention;  
       FIG. 5  is a front view illustrating a connection rubber of the air cleaner according to the embodiment of the present invention;  
       FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5 ;  
       FIG. 7  is a principal cross-sectional view showing the connection rubber according to the embodiment of the present invention;  
       FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 5 ;  
       FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 5 ; and  
       FIG. 10  is a view illustrating operation of the air cleaner structure according to the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference symbols.  
       FIG. 1  is a side elevational view showing a vehicle that adopts an air cleaner structure according to an embodiment of the present invention. A vehicle  10  is a four-wheel-drive, all terrain vehicle (ATV). The vehicle  10  includes a power unit  14  disposed substantially at a center of a vehicle body frame  11 . The power unit  14  includes a longitudinal engine  12  and a transmission  13 . A front propeller shaft  17  connects a front final assembly  16  disposed forward of the power unit  14  to the transmission  13 . A rear propeller shaft  21  connects a rear final assembly  18  disposed rearward of the power unit  14  to the transmission  13 .  
      The vehicle body frame  11  includes a pair of left and right lower frames  31 ,  32  (only reference numeral  31  representing the lower frame on a proximal side is shown), a pair of left and right upper frames  33 ,  34  (only reference numeral  33  representing the upper frame on the proximal side is shown), a pair of left and right front frames  36 ,  37  (only reference numeral  36  representing the front frame on a proximal side is shown), a pair of left and right front connection frames  41 ,  42  (only reference numeral  41  representing the front connection frame on the proximal side is shown), and a pair of left and right rear upper frames  43 ,  44  (only reference numeral  43  representing the rear upper frame on the proximal side is shown). More specifically, the lower frames  31 ,  32  support a lower portion of the power unit  14 . The upper frames  33 ,  34  are substantially C-shaped, and are disposed at an upper portion of the lower frames  31 ,  32  so as to enclose the power unit  14  in a side view. The front frames  36 ,  37  connect upper portions at a front of the upper frames  33 ,  34  and front end portions of the lower frames  31 ,  32 , respectively. The front connection frames  41 ,  42  connect the front frames  36 ,  37  and the upper frames  33 ,  34 , respectively. The rear upper frames  43 ,  44  extend rearwardly from upper rear portions of the upper frames  33 ,  34 . The rear upper frames  43 ,  44  have intermediate portions connected to rear ends of the lower frames  31 ,  32 .  
      The engine  12  includes a cylinder portion  51 , to which an intake system  53  and an exhaust system  54  are connected. The intake system  53  includes an air cleaner  56  and a throttle body  57 . The exhaust system  54  includes an exhaust pipe  61  and a muffler  62 .  
      The front final assembly  16  connects to left and right front wheels  68 ,  69  via a pair of left and right drive shafts  66 ,  67  (only reference numeral  66  representing the drive shaft on the proximal side is shown).  
      The rear final assembly  18  connects to left and right rear wheels  74 ,  75  via a pair of left and right drive shafts  72 ,  73  (only reference numeral  72  representing the drive shaft on the proximal side is shown).  
      A handlebar  77  steering the front wheels  68 ,  69  is supported by a steering shaft  78 . The steering shaft  78  has a front portion rotatably mounted on a cross pipe (not shown) disposed across front portions of the upper frames  33 ,  34 . Further, the steering shaft  78  includes a lower portion rotatably mounted onto a cross plate  79  disposed across the front connection frames  41 ,  42 .  
      In  FIG. 1 , a radiator  81  is provided together with a pair of left and right front shock absorber units  82 ,  83  (only reference numeral  82  representing the front shock absorber on the proximal side is shown). A fuel tank  84  is provided together with a fuel pump  86 . A front carrier  91  is provided together with a front fender  92 . A body cover  93  is provided together with a  94  represents a seat  94 . A rear carrier  96  is mounted adjacent to a swing arm  97  that swingably supports the rear final assembly  18 . A rear shock absorber unit  98  is disposed across the side of the rear upper frames  43 ,  44  and the side of the rear final assembly  18 . A rear fender  101  is mounted adjacent to a step floor  102 .  
       FIG. 2  is a plan view showing the vehicle according to the embodiment of the present invention. The vehicle  10  is a four-wheeled vehicle including an intake duct  111 , which forms part of the intake system  53 , disposed downwardly of the fuel tank  84  and the seat  94 . The intake duct  111  has a rear end connected to the air cleaner  56 .  
      In  FIG. 2 , occupant steps  115 ,  115  are provided together with a gearshift pedal  116 . A brake pedal  117  is provided together with a clutch lever  118  and a brake lever  121 .  
       FIG. 3  is a principal plan view illustrating the intake system according to an embodiment of the present invention (the arrow (FRONT) shown in  FIG. 3  indicates a forward direction of the vehicle; the same also applies hereunder). As illustrated in  FIG. 3  the air cleaner  56  is mounted to the left and right upper frames  33 ,  34  via brackets  125 ,  126 . A rear end of the intake duct  111  and a rear end of a connecting tube  127  are connected to a front portion of the air cleaner  56 . The throttle body  57  is connected to a front end of the connecting tube  127 . An intake pipe  131  is connected to a front end of the throttle body  57 . Further, a front end of the intake pipe  131  is connected to the cylinder portion  51  of the engine  12 . In  FIG. 3 , reference numeral  133  represents a filler cap of the fuel tank  84 .  
       FIG. 4  is a perspective view showing the air cleaner  56  and the intake duct  111  according to an embodiment of the present invention. The air cleaner  56  includes an air cleaner case  141  and an air cleaner element (not shown) disposed inside the air cleaner case  141 . The air cleaner case  141  includes a case main body  143 , a connection rubber  146 , and a case cover  147 . The connection rubber  146  is fitted to a side wall  143 a of the case main body  143  for connecting the intake duct  111  and the connecting tube  127  to the case main body  143 . The case cover  147  closes an opening in an upper portion of the case main body  143 . In  FIG. 4 , fixing brackets  151  are provided for fixing the case cover  147  to the case main body  143 . A tube portion  152  is integrated with the connection rubber  146 . An extension pipe  153  is connected to the tube portion  152  via a joint tube  154 . A plug  156  plugs an end portion of the extension pipe  153 .  
      The intake duct  111  includes an intake chamber  162 , a duct portion  163 , and a resonator  164 . The intake chamber  162  includes an intake port  161 , through which air is drawn in from the outside. The duct portion  163  has a first end integrally connected to the intake chamber  162  and a second end connected to a lower portion of the connection rubber  146 . The resonator  164  is connected to the duct portion  163 .  
       FIG. 5  is a front view illustrating the connection rubber  146  of the air cleaner  56  according to an embodiment of the present invention. The connection rubber  146  includes a sheet-like portion  171 , a duct connection portion  172 , a tube connection portion  173 , and a sensor mounting portion  174 . The sheet-like portion  171  is fitted in a mounting hole  143 b made in the side wall  143 a of the case main body  143 . The duct connection portion  172  is integrally formed with the sheet-like portion  171  for connecting the intake duct  111  (see  FIG. 4 ) at a lower portion of the sheet-like portion  171 . The tube connection portion  173  is integrally formed with the sheet-like portion  171  for connecting the connecting tube  127  (see  FIG. 3 ) at an upper portion of the sheet-like portion  171 . The sensor mounting portion  174  is integrally formed with the sheet-like portion  171  for mounting a temperature sensor at an edge portion of the sheet-like portion  171  on a side close to the duct connection portion  172 .  
      The sheet-like portion  171  includes a flat portion  171   a  disposed inside the mounting hole  143   b  and surrounded by the duct connection portion  172 , the tube connection portion  173 , and the sensor mounting portion  174 . The flat portion  171   a  is elastically deformed to a greater extent than other portions such that the sheet-like portion  171  can make a small change in pressure, or in particular, a pressure drop. The sheet-like portion  171  is provided with a large area so as to be easily deformed elastically.  
       FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5 . As illustrated in  FIG. 6 , the connection rubber  146  is fitted in the mounting hole  143   b  in the case main body  143 . An air cleaner element  178  is supported by an inner pipe portion  176  disposed inside the sheet-like portion  171  of the connection rubber  146  and the air cleaner case  141 . As illustrated in  FIG. 6 , an annular groove portion  171   b  is disposed in a peripheral edge of the sheet-like portion  171 . An outer surface  171 A of the flat portion  171   a  of the sheet-like portion  171  is provided together with an inner surface  171 B of the flat portion  171   a  of the sheet-like portion  171 .  
      The air cleaner element  178  includes a frame  181  and a filter assembly  182 . More specifically, the frame  181  includes a plurality of metal plate members. The filter assembly  182  is fitted to the frame  181 . The filter assembly  182  includes a filter  183 .  
      The air cleaner element  178  is secured in position as described below. More specifically, the frame  181  includes an inner tube portion  185 . The filter assembly  182  includes an outer tube portion  186 . The inner tube portion  176  of the connection rubber  146  is then fitted into an annular groove  187  formed between the inner tube portion  185  and the outer tube portion  186 . The case main body  143  includes a step portion  191 . The case cover  147  includes a rising wall  192  having an L-shaped cross section. The step portion  191  and the rising wall  192  clamp an end portion of the filter assembly  182  of the air cleaner element  178 . The air cleaner element  178  is thereby supported by the inner tube portion  176  of the connection rubber  146  and the air cleaner case  141 . In  FIG. 6 , a hose band  194  is provided that tightens the outer tube portion  186 , the inner pipe portion  176 , and the inner tube portion  185 . A drain pipe  195  is disposed on a bottom portion of the case main body  143  with a rubber cap  196  that plugs an opening at a lower portion of the drain pipe  195 .  
       FIG. 7  is a principal cross-sectional view showing the connection rubber  146  according to the embodiment of the present invention. More specifically,  FIG. 7  is a cross-sectional view showing the tube connection portion  173 .  
      The tube connection portion  173  includes an upper portion pipe portion  201  and an upper portion connection main body portion  202 . The upper portion pipe portion  201  projects integrally from the sheet-like portion  171 . The upper portion connection main body portion  202  is disposed integrally at a leading end of the upper portion pipe portion  201 .  
      The upper portion pipe portion  201  includes a connection hole  204 , an inner annular groove  207 , and an annular band groove  209 . The connection hole  204  receives the connecting tube  127  inserted therein. The inner annular groove  207  is disposed in a back side of the connection hole  204 . A flange  206  formed at a leading end of the connecting tube  127  is fitted into this inner annular groove  207 . The band groove  209  includes a portion tightened by a hose band  208 . The upper portion pipe portion  201  communicates the connection hole  204  and the inner annular groove  207  with a hollow portion  211  of the upper portion pipe portion  201 , a hollow portion  212  of the inner pipe portion  176 , and the air cleaner case  141  (see  FIG. 6 ), more specifically, an inside of the case main body  143 . In  FIG. 7 , an annular projection  214  is formed in the hollow portion  212 . The annular projection  214  provides sealing with respect to the inner tube portion  185  of the air cleaner element  178 .  
       FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 5 . The duct connection portion  172  includes a lower portion pipe portion  221  and a lower portion connection main body portion  222 . The lower portion pipe portion  221  projects integrally from the sheet-like portion  171 . The lower portion connection main body portion  222  is integrally formed with the lower portion pipe portion  221  at a leading end portion of the lower portion pipe portion  221 . Further, the lower portion connection main body portion  222  includes a connection hole  224  and an annular band groove  227 . The connection hole  224  receives the intake duct  111  inserted therein. The band groove  227  is tightened by a hose band  226 . The connection hole  224  includes two annular projections  228 ,  228  for improving the sealing performance relative to the intake duct  111 . The duct connection portion  172  communicates the connection hole  224  with a hollow portion of the lower portion pipe portion  221  and the air cleaner case  141  (see  FIG. 6 ), more specifically, the inside of the case main body  143 .  
       FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 5 . The sensor mounting portion  174  includes an outer bulged portion  241 , an inner bulged portion  242 , and a hole portion  243 . The outer bulged portion  241  is bulged from the outer surface  171 A of the sheet-like portion  171 . The inner bulged portion  242  is bulged from the inner surface  171 B of the sheet-like portion  171 . The hole portion  243  penetrates through an area from the outer bulged portion  241  to the inner bulged portion  242 .  
      The hole portion  243  includes fitting holes  246 ,  247 , a large diameter hole  248 , an annular peak portion  251 , and an inner hole portion  252 . A temperature sensor  245  is inserted and fitted in the fitting holes  246 ,  247 . The large diameter hole  248  is disposed between the fitting holes  246 ,  247  and has a diameter larger than those of the fitting holes  246 ,  247 . The annular peak portion  251  is formed to project inwardly from the large diameter hole  248 . The inner hole portion  252  is disposed adjacent a first fitting hole  247 , formed in the inner bulged portion  242 .  
      The temperature sensor  245  is mounted to the sensor mounting portion  174  as detailed below. More specifically, the temperature sensor  245  is inserted into the hole portion  243  and a nut  254  is screwed onto an external thread portion  245   a  formed on the temperature sensor  245 .  
      The annular peak portion  251  in the hole portion  243  is smaller in inner diameter than the fitting holes  246 ,  247 . Accordingly, when the temperature sensor  245  is inserted into the hole portion  243 , the annular peak portion  251  is compressed so as to provide sealing between the hole portion  243  and the temperature sensor  245 . As illustrated in  FIG. 9 , a detector portion  245   b  of the temperature sensor  245  is provided.  
      Effects of the air cleaner structure described heretofore will be described below.  
       FIG. 10  is a view illustrating the operation of the air cleaner structure according to the embodiment of the present invention.  
      If, for example, a throttle grip is suddenly operated in an attempt to accelerate the vehicle, air flows in the air cleaner case  141 , that is, a dirty side  257 , from the intake duct  111  via the duct connection portion  172  of the air cleaner  56  as shown by an arrow A. The air is then purified by the filter  183  and flows in the air cleaner element  178 , that is, a clean side  258  as shown by an arrow B. The air further flows in the connecting tube  127  via the tube connection portion  173  as shown by an arrow C. Referring back to  FIG. 3 , the air flows through the throttle body  57  and the intake pipe  131  to reach the cylinder portion  51  of the engine  12 .  
      Referring to  FIG. 10 , suction from the side of the engine  12  and air flow resistance of the intake duct  111 , the duct connection portion  172 , and the air cleaner element  178  act, at this time, to drop a pressure on the dirty side  257  and the clean side  258 . The drop in pressure flexes the flat portion  171   a  of the connection rubber  146  inwardly and, as a result, the drop in pressure on the dirty side  257  and the clean side  258  is minimized. Consequently, the air on the dirty side  257  and the clean side  258  is not prevented from flowing toward the side of the engine  12 .  
      If, for example, the pressure drop on the dirty side  257  and the clean side  258  is large, the decreased low pressure makes the flow of air to the engine side less smooth. In accordance with an embodiment of the present invention, however, the small drop in pressure ensures a smooth flow of air to the engine side. As a result, a large volume of air can be supplied to the engine  12  instantaneously, allowing an output of the engine  12  to be increased instantaneously. Thus, the response of the engine  12  to increase the engine speed when a throttle valve is suddenly opened, that is, the throttle response can therefore be improved.  
      As described heretofore with reference to  FIGS. 1 and 6 , according to the first embodiment of the present invention, the air cleaner structure for the vehicle  10  is provided, in which the air cleaner  56  is mounted to the vehicle body frame  11  and the air cleaner includes the intake duct  111  for drawing air in the air cleaner  56  and the connecting tube  127  (see  FIG. 3 ) for providing communication between the air cleaner  56  and the side of the engine  12 . The intake duct  111  and the connecting tube  56  are connected to the air cleaner  56 . The air cleaner structure according to the first aspect of the present invention is characterized in that the air cleaner  56  includes the connection rubber  146  as the elastic body capable of being flexed by a change in pressure in the air cleaner  56 . The connection rubber  146  is disposed on the side wall  143   a  as at least one of the walls of the air cleaner  56 .  
      As a result, if, for example, the throttle valve is suddenly opened, the connection rubber  146 , or more specifically, the flat portion  171   a  of the sheet-like portion  171  suppresses an instantaneous drop in pressure in the air cleaner  56 . This allows air to be quickly drawn into the engine  12 , thus improving throttle response.  
      The air cleaner structure according to the second embodiment of the present invention is characterized in that the intake duct  111  and the connecting tube  127  are supported by the single connection rubber  146 .  
      As a result, the connection rubber  146  supporting the intake duct  111  and the connecting tube  127  can be mounted to the air cleaner  56  at one time, as compared with an arrangement, in which an intake duct connection rubber and a connecting tube connection rubber are separately provided. Thus, the assemblability can therefore be improved and productivity enhanced.  
      Referring to  FIGS. 4 and 9 , the air cleaner structure according to the third embodiment of the present invention is characterized in that the vehicle  10  (see  FIG. 1 ) includes the temperature sensor  245  that measures the intake air temperature of the air cleaner  56  and the temperature sensor  245  is supported by the connection rubber  146 .  
      This improves assemblability of the temperature sensor  245  relative to the air cleaner  56  and prevents vibration from being transmitted to the temperature sensor  245 , as compared with an arrangement, in which a temperature sensor connection rubber is separately provided. Further, the connection rubber  146  can serve also as a sealing member for the sensor mounting portion  174 .  
      Referring to  FIGS. 5 and 6 , the air cleaner structure according to the fourth embodiment of the present invention is characterized in that the connection rubber  146  includes the outer surface  171 A and the inner surface  171 B of the flat portion  171   a  as an elastic surface other than the duct connection portion  172  and the tube connection portion  173 . The sensor mounting portion  174  serves as the support portion supporting the intake duct  111 , the connecting tube  127 , and the temperature sensor  245  (see  FIG. 9 ).  
      As a result, the outer surface  171 A and the inner surface  171 B other than the support portions  172  to  174  flex to reliably suppress a drop in pressure in the air cleaner  56 .  
      In addition, the connection rubber  146  includes the flat portion  171   a . This helps decrease the number of parts used and the cost, as compared with an arrangement, in which the flat portion is provided as a separate body from the connection rubber.  
      In accordance with the embodiment of the present invention, the sheet-like portion  171  includes the flat portion  171   a  disposed in an area of the connection rubber  146  surrounded by the duct connection portion  172 , the tube connection portion  173 , and the sensor mounting portion  174 . The arrangement is not limited to this; rather, the flat portion may be disposed inside the mounting hole  143   b  and outside the duct connection portion  172 , the tube connection portion  173 , or the sensor mounting portion  174 .  
      The air cleaner structure according to the embodiment of the present invention is preferably applicable to a two-wheeled vehicle of a four-wheeled vehicle.  
      The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.