Patent Publication Number: US-8991370-B2

Title: Intake apparatus of engine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to an intake apparatus of an engine provided with a fuel supplying device for supplying fuel into an intake passage. 
     2. Description of the Related Art 
     Heretofore, examples of an engine mounted on a vehicle such as a two-wheeled motor vehicle include a 2-stroke engine and a 4-stroke engine, and such an engine is provided with an intake apparatus. As the intake apparatus, there is one provided with a fuel supplying device for supplying fuel into an intake passage (Japanese Patent Application Laid-Open No. H07-317613). 
     Such an intake apparatus is supplied with a mixture of air and fuel. To improve the filling efficiency of the air-fuel mixture, there is an intake apparatus in which a straightening plate or the like is arranged in the intake passage. However, just straightening the air-fuel mixture by the straightening plate in this manner does not bring about a sufficient atomization of the air-fuel mixture and reduction in the harmful components in exhaust gas. 
     The present disclosure has been made with the view to such circumstances, and an object of the present disclosure is to provide an intake apparatus of an engine that improves an atomizing rate of an air-fuel mixture, improves combustion efficiency and fuel consumption, and reduces harmful components in exhaust gas. 
     SUMMARY OF THE INVENTION 
     To solve the above problems and to achieve the object, the present disclosure is configured as follows. 
     A first aspect of the present disclosure is an intake apparatus of an engine provided with a fuel supplying device for supplying fuel into an intake passage, the intake apparatus including: a guide body having multiple holes disposed in the intake passage located downstream from the fuel supplying device, wherein the guide body has a stepped portion extending in a direction intersecting with a direction of a flow of intake air. 
     A second aspect of the present disclosure is an intake apparatus of an engine provided with a fuel supplying device for supplying fuel into an intake passage, the intake apparatus including: a guide body having multiple holes disposed in the intake passage located downstream from the fuel supplying device, wherein the guide body has a curved cross-section, and separated passages separated by the guide body are formed in the intake passage. 
     A third aspect of the present disclosure is an intake apparatus of an engine provided with a fuel supplying device for supplying fuel into an intake passage, the intake apparatus including: a guide body having multiple holes disposed in the intake passage located downstream from the fuel supplying device, wherein the guide body has a stepped portion extending in a direction intersecting with a direction of a flow of intake air and has a curved cross-section, and separated passages separated by the guide body are formed in the intake passage. 
     A fourth aspect of the present disclosure is the intake apparatus of an engine according to any one of first to third aspect, wherein a plurality of the stepped portions is arranged in parallel. 
     A fifth aspect of the present disclosure is the intake apparatus of an engine according to any one of first to fourth aspects, wherein the holes are formed at parts displaced from the stepped portion. 
     A sixth aspect of the present disclosure is the intake apparatus of an engine according to any one of first to fifth aspects, wherein the multiple holes located upstream of the flow of the intake air are different from the multiple holes located downstream of the flow of the intake air in size. 
     A seventh aspect of the present disclosure is the intake apparatus of an engine according to any one of first to sixth aspects, wherein the holes located upstream of the flow of the intake air are larger and the holes located downstream of the flow of the intake air are smaller. 
     An eighth aspect of the intake apparatus of an engine according to any one of first to seventh aspects, wherein each of the holes is a choking hole whose passage cross-sectional area is narrowed on one side. 
     A ninth aspect of the present disclosure is the intake apparatus of an engine according to the eighth aspect, wherein the choking hole includes a large-diameter passage portion and a small-diameter passage portion. 
     A tenth aspect of the present disclosure is the intake apparatus of an engine according to the eighth aspect, wherein the choking hole is gradually narrowed from a large-diameter passage to a small-diameter passage. 
     An eleventh aspect of the present disclosure is the intake apparatus of an engine according to the ninth or tenth aspect, wherein the choking holes are arranged so that narrowed sides the respective choking holes are alternately located on opposite sides of the guide body. 
     A twelfth aspect of the present disclosure is the intake apparatus of an engine according to any one of the first to seventh aspects, wherein the holes are through holes where passage cross-sectional areas of the respective holes are equal to one another. 
     A thirteenth aspect of the present disclosure is the intake apparatus of an engine according to any one of the first to twelfth aspects, wherein the guide body having the multiple holes is disposed in the intake passage of a 2-stroke engine. 
     A fourteenth aspect of the present disclosure is the intake apparatus of an engine according to any one of fist to twelfth aspects, wherein the guide body having the multiple holes is disposed in the intake passage of a 4-stroke engine. 
     The present disclosure has the following effects by the above configurations. 
     According to the first aspect of the present disclosure, the guide body having the multiple holes is disposed in the intake passage located downstream from the fuel supplying device and has the stepped portion extending in the direction intersecting with the direction of the flow of the intake air. Consequently, fuel supplied from the fuel supplying device is mixed with air, and the intake air changes in flow rate and is atomized through further generation of turbulence due to the stepped portion of the guide body having the multiple holes. Since the air-fuel mixture atomized in the two stages is supplied, combustion efficiency and fuel consumption are improved. Also, since fuel components in the atomized air-fuel mixture remain in the plural holes as droplets, and the residual air-fuel mixture is supplied in the subsequent intake stroke, the combustion efficiency is further improved, and harmful components in exhaust gas can be reduced. 
     According to the second aspect of the present disclosure, the guide body having the multiple holes is disposed in the intake passage located downstream from the fuel supplying device and has the curved cross-section, and the separated passages separated by the guide body are formed in the intake passage. Consequently, fuel supplied from the fuel supplying device is mixed with air, and the intake air changes in flow rate in the separated passages separated by the curve of the guide body having the curved cross-section and is atomized through further generation of turbulence due to the guide body having the multiple holes. Since the air-fuel mixture atomized in the two stages is supplied, combustion efficiency and fuel consumption are improved. Also, since fuel components in the atomized air-fuel mixture remain in the plural holes as droplets, and the residual air-fuel mixture is supplied in the subsequent intake stroke, the combustion efficiency is further improved, and harmful components in exhaust gas can be reduced. 
     According to the third aspect of the present disclosure, the guide body having the multiple holes is disposed in the intake passage located downstream from the fuel supplying device, has the stepped portion extending in the direction intersecting with the direction of the flow of the intake air, and has the curved cross-section, and the separated passages separated by the guide body are formed in the intake passage. Consequently, fuel supplied from the fuel supplying device is mixed with air, the intake air changes in flow rate due to the stepped portion of the guide body having the multiple holes, and the intake air changes in flow rate in the separated passages separated by the curve of the guide body having the curved cross-section and is atomized through further generation of turbulence. Since the air-fuel mixture atomized in the two stages is supplied, combustion efficiency and fuel consumption are improved. Also, since fuel components in the atomized air-fuel mixture remain in the plural holes as droplets, and the residual air-fuel mixture is supplied in the subsequent intake stroke, the combustion efficiency is further improved, and harmful components in exhaust gas can be reduced. 
     According to the fourth aspect of the present disclosure, the intake air hits against the plural parallel stepped portions and is atomized through further generation of turbulence, and combustion efficiency and fuel consumption are improved. 
     According to the fifth aspect of the present disclosure, by forming the holes at the parts displaced from the stepped portion, the intake air hits against the stepped portion and is atomized through further generation of turbulence by the holes, and combustion efficiency and fuel consumption are improved. 
     According to the sixth aspect of the present disclosure, the multiple holes have different sizes on the upstream side and the downstream side in the direction of the flow of the intake air, and thus the intake air is atomized through further generation of turbulence. 
     According to the seventh aspect of the present disclosure, the holes are larger on the upstream side in the direction of the flow of the intake air and smaller on the downstream side, and thus the intake air is atomized through further generation of turbulence on the upstream side while the blown-back air-fuel mixture can be stopped on the downstream side. 
     According to the eighth aspect of the present disclosure, each of the holes is a choking hole whose passage cross-sectional area is narrowed on one side. Consequently, the intake air changes in flow rate and is atomized through further generation of turbulence. 
     According to the ninth aspect of the present disclosure, the choking hole includes the large-diameter passage portion and the small-diameter passage portion. Consequently, the intake air changes in flow rate due to a change in passage diameter and is atomized through further generation of turbulence. 
     According to the tenth aspect of the present disclosure, the choking hole is gradually narrowed from the large-diameter passage to the small-diameter passage. Consequently, the intake air changes in flow rate due to a change in passage diameter and is atomized through further generation of turbulence. 
     According to the eleventh aspect of the present disclosure, the choking holes are arranged to alternate the narrowed sides on both sides of the guide body, and thus the intake air is atomized through further generation of turbulence. 
     According to the twelfth aspect of the present disclosure, each of the holes is the through hole having the equal passage cross-sectional area, and thus the intake air is higher in flow rate and is atomized through further generation of turbulence. 
     According to the thirteenth aspect of the present disclosure, the guide body having the multiple holes is disposed in the intake passage of the 2-stroke engine. Consequently, combustion efficiency and fuel consumption are improved in the 2-stroke engine. 
     According to the fourteenth aspect of the present disclosure, the guide body having the multiple holes is disposed in the intake passage of the 4-stroke engine. Consequently, combustion efficiency and fuel consumption are improved in the 4-stroke engine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross-sectional view depicting a 2-stroke engine provided with an intake apparatus; 
         FIG. 2  is a cross-sectional view taken along the line II-II in  FIG. 1 ; 
         FIG. 3  is a vertical cross-sectional view depicting a 4-stroke engine provided with an intake apparatus; 
         FIG. 4  is a cross-sectional view depicting an intake passage in a state of having a guide body of a first embodiment arranged therein; 
         FIGS. 5A to 5D  are plan views each depicting the guide body; 
         FIGS. 6A to 6D  are plan views each depicting the guide body; 
         FIGS. 7A to 7D  are cross-sectional views each depicting the guide body; 
         FIGS. 8A to 8C  are plan views each depicting the guide body; 
         FIGS. 9A to 9C  are cross-sectional views each depicting the hole part of the guide body; 
         FIG. 10  is a perspective view depicting the guide body of a second embodiment; 
         FIG. 11  is a schematic perspective view depicting a state of arranging the guide body in the intake passage; 
         FIG. 12  is a cross-sectional view depicting the intake passage in which the guide body is arranged; 
         FIG. 13  is a perspective view depicting the guide body of a third embodiment; 
         FIG. 14  is a cross-sectional view depicting the intake passage in which the guide body is arranged; and 
         FIGS. 15A to 15D  are cross-sectional views each depicting the intake passages in which the guide bodies of a fourth embodiment are arranged. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of an intake apparatus of an engine according to the present disclosure will be described below with reference to the accompanying drawings, but the present disclosure is not limited to these embodiments. 
     Configuration of Engine 
     (2-Stroke Engine) 
       FIGS. 1 and 2  illustrates an embodiment made by applying the present disclosure to a 2-stroke engine, where  FIG. 1  is a vertical cross-sectional view of the 2-stroke engine provided with an intake apparatus and  FIG. 2  is a cross-sectional view taken along the line II-II in  FIG. 1 . 
     According to the present disclosure, in the intake apparatus of the engine provided with a fuel supplying device for supplying fuel into an intake passage, a guide body  200  having multiple holes  201  is disposed in the intake passage located downstream from the fuel supplying device. 
     The engine of the present embodiment is a 2-stroke engine  1 , and the 2-stroke engine  1  includes a crank case  2  having an upper case  3  and a lower case  4 . A crank shaft  5  is pivotally supported between the upper case  3  and the lower case  4 , and a crank chamber  6  is constructed of the upper case  3  and the lower case  4 . 
     A cylinder block  7  is attached to the upper case  3 , and a cylinder head  8  is attached to the cylinder block  7 . A piston  10  is reciprocally disposed in a cylinder  9  formed in the cylinder block  7 . A combustion chamber  11  is a space defined by the cylinder  9 , the head of the piston  10 , and the cylinder head  8 . A spark plug  12  is attached to the cylinder head  8 , while facing the combustion chamber  11 . In the cylinder block  7 , there are three scavenging passages  13  and an exhaust passage  14 . The scavenging passages  13  make the crank chamber  6  communicate with the combustion chamber  11  in the scavenging stroke, and the exhaust passage  14  discharges exhaust gas in the combustion chamber  11  in the exhaust stroke. Two of the three scavenging passages  13  are oppositely arranged to each other in a radial direction of the cylinder  9  while the other scavenging passage  13  is oppositely arranged opposite to the exhaust passage  14  between the two opposed scavenging passages  13 . 
     Two piston rings  15  are disposed on the upper portion of the piston  10 . A small end  21   a  of a connecting rod  21  is rotatably supported by a piston pin  20  through a bearing  22 , where the piston pin  20  is provided at the piston  10 . In addition, a large end  21   b  of the connecting rod  21  is supported by a crank pin  23  of the crank shaft  5  through a bearing  24 . By the connecting rod  21 , the reciprocating motion of the piston  10  is converted into a rotating motion and is transmitted to the crank shaft  5 . 
     An intake pipe  30  is connected to the upper case  3  of the crank case  2  through a reed valve  70 . Furthermore, a carburetor  31  is connected to the intake pipe  30  and serves as a fuel supplying device. In the reed valve  70 , an intake port  72  is formed in a body  71 , and a valve  73  and a valve stopper  74  that open and close the intake port  72  are fastened together with a screw  75 . The valve  73  of the reed valve  70  opens during the intake stroke, in which the crank chamber  6  is under negative pressure, to intake an air-fuel mixture from an intake passage  30   a  of the intake pipe  30 . In this manner, the reed valve  70  allows only a flow of intake air from the intake pipe  30  to the crank chamber  6 . The crank chamber  6  serves as a primary compression chamber for the intake air. 
     In the reed valve  70  arranged at the intake passage  30   a  located downstream from the carburetor  31  as a fuel supplying device, the guide body  200  having the multiple holes  201  is disposed. The guide body  200  is in a plate shape and made of a metal, such as aluminum, stainless steel, or copper; a carbon material; a wood; or a bamboo. 
     As a result of disposing the guide body  200  having the multiple holes  201  in the intake passage of the 2-stroke engine  1 , fuel supplied from the fuel supplying device is mixed with air in the 2-stroke engine  1 , and the intake air changes in flow rate and is atomized through further generation of turbulence due to the guide body  200  having the multiple holes  201 . Since the air-fuel mixture atomized in the two stages is supplied, combustion efficiency and fuel consumption are improved. Also, since fuel components in the atomized air-fuel mixture remain in the plural holes as droplets, and the residual air-fuel mixture is supplied in the subsequent intake stroke, the combustion efficiency is further improved, and harmful components in exhaust gas can be reduced. 
     (4-Stroke Engine) 
     Next, an embodiment made by applying the present disclosure to a 4-stroke engine will be described.  FIG. 3  is a vertical cross-sectional view of the 4-stroke engine provided with an intake apparatus. 
     In the present embodiment, a cylinder head  103  is attached to a cylinder block  102  of a 4-stroke engine  101  having multiple cylinders and is constituted by a head lower portion  104  and a head upper portion  105 . A combustion chamber  107  is a space defined by the head lower portion  104  and a piston  106  fitted in the cylinder block  102 , and a head cover  108  is attached to the head upper portion  105 . An intake passage  109  is formed in the head lower portion  104  and is opened to the combustion chamber  107  by three branching passages  109   a.    
     The branching passages  109   a  of the intake passage  109  are provided with an intake valve  112 , respectively. Thus, the intake valve  112  is opened and closed to supply an air-fuel mixture to the combustion chamber  107 . Also, an exhaust passage  115  is formed in the head lower portion  104 , in which a pair of branching passages  115   a  is opened to the combustion chamber  107 . The branching passages  115   a  are provided with exhaust valves (not shown), respectively. Thus, the exhaust value is opened and closed to discharge exhaust gas from an exhaust pipe (not shown) connected to the exhaust passage  115 . 
     An intake pipe  110  is connected to the intake passage  109  and is provided with an injector  111  as a fuel supplying device. The injector  11  injects fuel at a predetermined timing. Also, a spark plug  150  is attached to the head lower portion  104  while facing the combustion chamber  107 . 
     In the intake passage  109  located downstream from the injector  111  provided as a fuel supplying device, the guide body  200  having the multiple holes  201  is disposed along a direction of a flow of intake air. 
     Fuel supplied from the injector  111  is mixed with air, and the intake air is atomized through further generation of turbulence due to the guide body  200  having the multiple holes  201 . Since the air-fuel mixture atomized in the two stages is supplied, combustion efficiency is improved. As a result, a further improvement in fuel consumption is attained. Also, the combustion efficiency is further improved because fuel components in the atomized air-fuel mixture remain in the plural holes  201  of the guide body  200  as droplets and the residual air-fuel mixture is supplied in the subsequent intake stroke. 
     Also, regardless of an attaching direction of the intake passage  109 , an atomizing rate of the air-fuel mixture can be further improved without decreasing the flow rate of the flow of the intake air, the combustion efficiency and the fuel consumption can be improved, and harmful components in exhaust gas, such as carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx), can be reduced. 
     Configuration of Guide Body 
     First Embodiment 
     Configurations of the guide body in a first embodiment are illustrated in  FIGS. 4 to 9 .  FIG. 4  is a cross-sectional view depicting an intake passage in a state of having the guide body arranged therein,  FIGS. 5A to 5D  and  6 A to  6 D are plan views each depicting the guide body,  FIGS. 7A to 7D  are cross-sectional views depicting the guide body,  FIGS. 8A to 8C  are plan views each depicting the guide body, and  FIGS. 9A to 9C  are cross-sectional views each depicting the hole part of the guide body. In the first embodiment, the guide body  200  having the multiple holes  201  is disposed in an intake passage  300  located downstream from a fuel supplying device and has stepped portions  202  each extending in a direction intersecting with a direction of a flow of intake air, and a plurality of stepped portions  202  are arranged in parallel. The multiple holes  201  are formed by a punching process, a cutting process, or the like, and the stepped portions  202  are formed by a bending process, a cutting process, or the like. Also, the holes  201  are formed at parts displaced from the stepped portions  202 . 
     In the first embodiment, the guide body  200  having the multiple holes  201  is disposed in the intake passage  300  located downstream from the fuel supplying device, is in a plate shape, and has the stepped portions  202  extending in the direction intersecting with the direction of the flow of the intake air. Consequently, fuel supplied from the fuel supplying device is mixed with air due to the multiple holes  201 , and the intake air changes in flow rate as the intake air hits against the stepped portions  202  and is atomized through further generation of turbulence. Since an air-fuel mixture atomized in the two stages is supplied, the combustion efficiency and fuel consumption are improved. 
     In the embodiments in  FIGS. 5A to 5D , although the stepped portions  202  extend approximately at an angle of 45 degrees with respect to the direction intersecting with the direction of the flow of the intake air, the angle is not limited to this but may be any angle as long as it is an angle not perpendicular to the direction, and the intake air can change in flow rate as the intake air hits the stepped portions  202 . In  FIG. 5A , two stepped portions  202  intersect with each other at an angle of approximately 45 degrees and are configured so that the intersection may be located upstream of the flow of the intake air, in  FIG. 5B , two stepped portions  202  are configured so that the intersection may be located downstream of the flow of the intake air, and in  FIGS. 5C and 5D , one stepped portion  202  is configured to extend at an angle of approximately 45 degrees. Also, by arranging plural stepped portions  202  in parallel, the intake air hits against the plural parallel stepped portions  202  and is atomized through further generation of turbulence, and the combustion efficiency and the fuel consumption are improved. 
     In the embodiments in  FIGS. 6A to 6D , the stepped portions  202  are in circular arcs and extend at a predetermined angle with respect to the direction intersecting with the direction of the flow of the intake air. In  FIG. 6A , the stepped portion  202  is configured so that the projecting side of the circular arc-stepped portion  202  may be located at the center of the upstream side in the direction of the flow of the intake air, in  FIG. 6B , the stepped portion  202  is configured so that the projecting side of the circular arc-stepped portion  202  may be located at the center of the downstream side in the direction of the flow of the intake air, in  FIG. 6C , the stepped portion  202  is configured so that the projecting side of the circular arc-stepped portion  202  may be obliquely located upstream of the flow of the intake air, and in  FIG. 6D , the stepped portion  202  is configured so that the projecting side of the circular arc-stepped portion  202  may be obliquely located downstream of the flow of the intake air. 
     In the first embodiment, the stepped portion  202  is formed by a bending process by pressure molding. In  FIG. 7A , the stepped portion  202  has a cross-section of a trapezoidal shape. In  FIG. 7B , the stepped portion  202  has a cross-section of a curved shape. In  FIG. 7C , the stepped portion  202  has a cross-section of a triangular shape. In  FIG. 7D , the stepped portion  202  has a cross-section of a U shape. The cross-sectional shape of the stepped portion  202  is not limited to any of those in the present embodiment. 
     Next, configurations of the hole of the guide body in the first embodiment are illustrated in  FIGS. 8A to 8C  and  9 A to  9 C.  FIGS. 8A to 8C  are plan views each depicting the guide body, and  FIGS. 9A to 9C  are cross-sectional views each depicting the guide body. The multiple holes  201  of the guide body  200  located upstream of the flow of the intake air are different from those located downstream thereof in size. Thus, the holes  201  with different sizes cause the intake air to be atomized through further generation of turbulence. Also, the multiple holes  201  are formed at parts displaced from the stepped portions  202 . Consequently, the intake air hits against the stepped portions  202  and is atomized by the holes  201  through the further generation of turbulence, and the combustion efficiency and the fuel consumption are improved. 
     In  FIG. 8A , the holes  201  located upstream of the flow of the intake air are configured to be larger and those located downstream thereof are configured to be smaller. In  FIG. 8B , the holes  201  are configured to be gradually smaller from upstream to downstream of the flow of the intake air. In  FIG. 8C , the holes  201  are configured to be smaller on the upstream side in the direction of the flow of the intake air, larger at the center, and smaller on the downstream side of the flow. 
     In  FIG. 9A , each of the holes  201  is a through hole having an equal passage cross-sectional area. In  FIG. 9B , each of the holes  201  is a choking hole whose passage cross-sectional area is narrowed on one side and is gradually narrowed from a large-diameter passage  201   a  to a small-diameter passage  201   b . In  FIG. 9C , each of the holes  201  is a choking hole and includes a large-diameter passage portion  201   c  and a small-diameter passage portion  201   d . In a case where the holes  201  are choking holes, they can be arranged to alternate the narrowed sides on both sides of the guide body  200  as depicted in  FIGS. 9B and 9C . When each of the holes  201  is a choking hole whose passage cross-sectional area is narrowed on one side in this manner, the intake air further changes in flow rate by the choking holes and is atomized through the further generation of turbulence. 
     Second Embodiment 
     A configuration of the guide body in a second embodiment is shown in  FIGS. 10 to 12 .  FIG. 10  is a perspective view of the guide body,  FIG. 11  shows a state of arranging the guide body in the intake passage, and  FIG. 12  is a cross-sectional view of the intake passage in which the guide body is arranged. In the second embodiment, the guide body  200  having the multiple holes  201  is disposed in the intake passage located downstream from a fuel supplying device. 
     The guide body  200  has a curved cross-section and forms separated passages  301  and  302  separated by the guide body  200  in the intake passage  300 . The guide body  200  has the multiple holes  201 , and the holes  201  are arranged to have equal sizes in a direction of a flow of intake air in  FIG. 10  and are configured in a similar manner to that of the first embodiment. 
     In the second embodiment, the guide body  200  having the multiple holes  201  is disposed in the intake passage  300  located downstream from the fuel supplying device, has the curved cross-section, and forms the separated passages  301  and  302  separated by the guide body  200  in the intake passage  300 . Consequently, fuel supplied from the fuel supplying device is mixed with air, and the intake air changes in flow rate in the separated passages  301  and  302  separated by the curve of the guide body  200  having the curved cross-section. That is, the flow rate in the separated passage  301  formed by the side of a projecting surface  200   a  of the curve of the guide body  200  is higher than the flow rate in the separated passage  302  formed by the side of a recessed surface  200   b  of the curve of the guide body  200 . Also, the intake air is atomized through further generation of turbulence due to the multiple holes  201  of the guide body  200 . Since an air-fuel mixture atomized in the two stages is supplied, combustion efficiency and fuel consumption are improved. 
     Third Embodiment 
     A configuration of the guide body in a third embodiment is illustrated in  FIGS. 13 and 14 .  FIG. 13  is a perspective view of the guide body, and  FIG. 14  is a cross-sectional view of the intake passage in which the guide body is arranged. In the third embodiment, the guide body  200  having the multiple holes  201  is disposed in the intake passage located downstream from a fuel supplying device. 
     The guide body  200  has a curved cross-section in a similar manner to that of the second embodiment and forms the separated passages  301  and  302  separated by the guide body  200  in the intake passage  300 . The guide body  200  of the third embodiment has the stepped portions  202  each extending in a direction intersecting with a direction of a flow of intake air, and the stepped portions  202  are configured in a similar manner to that in the first embodiment. 
     In the third embodiment, the guide body  200  having the multiple holes  201  is disposed in the intake passage  300  located downstream from the fuel supplying device, has the stepped portions  202  each extending in the direction intersecting with the direction of the flow of the intake air, has the curved cross-section, and forms the separated passages  301  and  302  separated by the guide body  200  in the intake passage  300 . Consequently, fuel supplied from the fuel supplying device is mixed with air, and the intake air changes in flow rate due to the stepped portions  202  of the guide body  200  having the multiple holes  201 . 
     The intake air further changes in flow rate in the separated passages  301  and  302  separated by the curve of the guide body  200  having the curved cross-section. That is, the flow rate in the separated passage  301  formed by the side of the projecting surface  200   a  of the curve of the guide body  200  is higher than the flow rate in the separated passage  302  formed by the side of the recessed surface  200   b  of the curve. Also, the intake air is atomized through further generation of turbulence due to the multiple holes  201  of the guide body  200 . Since an air-fuel mixture atomized in the two stages is supplied, combustion efficiency and fuel consumption are improved. 
     Fourth Embodiment 
     Configurations of the guide body in a fourth embodiment are illustrated in  FIGS. 15A to 15D .  FIGS. 15A to 15D  are cross-sectional views of the intake passages in which the guide bodies are arranged. In the fourth embodiment, the guide body  200  having the multiple holes  201  is disposed in the intake passage located downstream from a fuel supplying device. Although the guide body  200  of the present embodiment differs from those of the first to third embodiments in terms of a tubular shape, it is configured in a similar manner in other respects. Thus, the description is omitted. 
       FIG. 15A  illustrates an example of the embodiment in which the guide body  200  has a circular cross-section.  FIG. 15B  illustrates another example of the embodiment in which the guide body  200  has a triangular cross-section in an embodiment.  FIG. 15C  illustrates another example of the embodiment in which the guide body  200  has an octagonal cross-section in an embodiment.  FIG. 15D  illustrates another example of the embodiment in which the guide body  200  has a hexagonal cross-section in an embodiment. Each of them is arranged in the intake passage  300  by a pair of ribs  210 . The pair of ribs  210  may be fixed in the intake passage  300  by press fitting or by engagement with recesses. Also, the pair of ribs  210  may be provided with holes. In the present embodiment, the surface area of the guide body  200  is secured to enable further generation of turbulence. 
     The present disclosure is an engine mounted in a vehicle such as a two-wheeled motor vehicle, is applied to an intake apparatus of a 2-stroke engine or a 4-stroke engine, improves an atomizing rate of an air-fuel mixture, improves combustion efficiency and fuel consumption, and reduces harmful components in exhaust gas.