Abstract:
A system for discharging exhaust air from a radiator in a straddle type vehicle (e.g., a motorcycle) is provided that can discharge heated air from the radiator to the outside of the vehicle in an efficient manner. The system comprises a radiator that can be positioned farther forward than an engine in the straddle type vehicle. A front cowl at least partially covers the front portion of the vehicle, including the radiator and engine. The front cowl comprises at least one vent passage for receiving outside air and directing such air rearward and at least one discharge port for discharging exhaust air from the radiator. Because of a pressure difference occurring due to high-speed air current flowing along the at least one vent passage, the heated exhaust air can be positively discharged from the radiator through the at least one discharge port.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is based on and claims priority under 35 U.S.C. § 119(a)-(d) to Japanese Patent Application No. 2005-029816, filed Feb. 4, 2005, the entire contents of which is hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to straddle type vehicles (e.g., motorcycles) and, in particular, to a straddle type vehicle having a system for discharging exhaust air from a radiator adapted to efficiently discharge such exhaust air to the outside of the vehicle. 
   2. Description of the Related Art 
   Motorcycles typically have an engine disposed in a longitudinally central portion of a vehicle body, a radiator positioned in front of the engine, and a front cowl disposed on a front portion of the vehicle so as to cover a front surface of the vehicle body. The front cowl often includes air discharge ports in its side walls, which are adapted to discharge the exhaust air that has passed through the radiator. Such constructions are taught, for instance, by Japanese Utility Model Publication JP-UM-B-5-9995, Japanese Utility Model JP-UM-B-4-50228 and Japanese Patent Publication No. JP-A-62-283082. 
   Coolant circulates through the radiator and is used to cool various engine components. The radiator receives cool air that flows through the radiator in order to conduct heat away from the radiator and thereby reduce the temperature of the circulating coolant. Outside air (i.e., cool air) is typically delivered to the radiator while the motorcycle is operating via openings positioned in the center portion of a front wall of the front cowl. After such air passes through the radiator, heated exhaust air is sent out of the radiator through air discharge ports. In typical front cowl assemblies, forward movement of the motorcycle forces outside air to travel rearward along the side surfaces of the front cowl. The exhaust air exiting the air discharge ports is drawn out of the radiator by the outside air flowing along the side surfaces of the front cowl. As a result, the discharge of exhaust air from the radiator is dependent on the air flow along the side surfaces of the front cowl and, therefore, is limited. 
   SUMMARY OF THE INVENTION 
   To address the aforementioned limitation, an object of the present invention is to provide a straddle type vehicle (e.g., a motorcycle) that can efficiently discharge the exhaust air that has passed through the radiator to the outside of the vehicle by providing vent passages that force outside air to flow rearward along the side surfaces of the front cowl. 
   One aspect of the present invention involves a straddle type vehicle comprising a frame. The frame is supported by a wheel. The wheel rotates about a generally horizontal axis. An engine is supported by the frame. A radiator is positioned generally forward of the engine. A front cowl encloses at least a portion of the frame. The front cowl extends from a location generally over the front wheel to a location proximate the engine. The front cowl generally defines a chamber in which the radiator is positioned. An air discharge port is defined in a side surface of the front cowl at a location generally rearward of the radiator. The discharge port is capable of receiving air that has passed through the radiator. A vent passage is defined along a longitudinal portion of the side surface of the front cowl. At least a portion of the longitudinal portion is positioned vertically above the air discharge port. The vent passage has a forward facing opening such that air through which the vehicle operates can be directed into the vent passage and at least a portion of the vent passage comprises a generally c-shaped cross-section. 
   An aspect of the present invention also involves a straddle type vehicle comprising at least one wheel that rotates about a generally horizontal axis and a vehicle body supported at least in part by the at least one wheel. The vehicle body supports an engine and a radiator such that the radiator, in one embodiment, is positioned farther forward than the engine. A front cowl having at least one side wall covers the front portion of the vehicle body and includes at least one vent passage and at least one discharge port. The at least one vent passage receives outside air and directs such air rearward along the at least one side wall of the front cowl, while the at least one discharge port discharges heated exhaust air from the radiator to the outside of the vehicle. 
   An additional aspect of the present invention involves a straddle type vehicle having at least one wheel and a vehicle body supported by the at least one wheel. The vehicle body includes a front portion having a front end. The vehicle body supports an engine and a radiator such that the radiator, in one embodiment, is positioned farther forward than the engine. A front cowl is provided which comprises an upper cowl, a middle cowl, and a lower cowl. At least one vent passage and at least one discharge port are disposed on the front cowl. The at least one vent passage includes at least one extension that extends the at least one vent passage in a generally longitudinal direction to a position above and substantially near the at least one discharge port. 
   In accordance with an additional aspect of the present invention, a straddle type vehicle comprises at least one wheel that rotates about a generally horizontal axis, a vehicle body supported at least in part by the at least one wheel, and a radiator supported at least in part by the vehicle body. The vehicle also includes a front cowl that at least partially covers a front portion of the vehicle body. In this embodiment, the front cowl comprises at least one vent passage for receiving air from outside of the vehicle and directing such air rearward and at least one discharge port for discharging exhaust air from the radiator to the outside of the vehicle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects, and advantages of the present invention will now be described in connection with a preferred embodiment of the invention shown in the accompanying drawings. The illustrated embodiment, however, is merely an example and is not intended to limit the invention. The drawings include thirteen figures. 
       FIG. 1  is a left side elevational view of a straddle type vehicle including a system for discharging exhaust air from a radiator of the vehicle, which system is arranged and configured in accordance with a preferred embodiment of the present invention. The straddle type vehicle is shown in a condition where no riders are seated on the vehicle, the front and rear wheels are both on the ground, and the vehicle is not leaning to a side or supported by a main stand. 
       FIG. 2  is a right side elevational view of the straddle type vehicle of  FIG. 1 . 
       FIG. 3  is an enlarged front view of an upper portion of the straddle type vehicle of  FIG. 1 . 
       FIG. 4  is a perspective view taken from the front of the vehicle showing a right side portion of the straddle type vehicle of  FIG. 1 . 
       FIG. 5  is a perspective view taken from the rear of the vehicle showing a front right side portion of the straddle type vehicle of  FIG. 1 . The straddle type vehicle is shown having a rider seated on the vehicle. 
       FIG. 6  is a front view of a front cowl of the straddle type vehicle of  FIG. 1 . 
       FIG. 7  is a side elevational view of the front cowl shown in  FIG. 6 . 
       FIG. 8  is an enlarged side view of an upper portion of the front cowl shown in  FIG. 6 . 
       FIG. 9  is a cross-sectional view of the upper portion of the front cowl taken along line IX-IX of  FIG. 8 . 
       FIG. 10  is a front view of a lower cowl disposed on the front cowl shown in  FIG. 6 . 
       FIG. 11  is a side elevational view of the lower cowl shown in  FIG. 10 . 
       FIG. 12  is a side elevational view of an upper cowl disposed on the front cowl shown in  FIG. 6 . 
       FIG. 13  is a side elevational view of a middle cowl disposed on the front cowl shown in  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A system for discharging exhaust air from a radiator is illustrated in the drawings and is described below in the context of a straddle type vehicle. However, the system can be used with other types of vehicles. Preferably, the system can be used with vehicles which have a wheel that rotates about a generally horizontal axis, a steering column, a steering mechanism coupled to the top of the steering column, and a straddle type seat located substantially near the steering column. For example, such vehicles in which the system described herein can be employed include, but are not limited to, a motorcycle, a motorized scooter, and a multi-terrain vehicle. Accordingly, the following description and the drawings describe a motorcycle; however, the present system for discharging exhaust air from a radiator can be used on other types of straddle type vehicles as well. 
   Embodiments of the present invention will now be described with reference to the accompanying drawings. As shown in  FIGS. 1 and 2 , a straddle type vehicle (e.g., a motorcycle) is provided that has the following components: a body frame  20 ; a front wheel  1 ; a rear wheel  2 ; an engine  3 ; a radiator  4 ; a front fork  5 ; a handlebar  6 ; a fuel tank  7 ; an air cleaner  8 ; a fuel injection system  9 ; a pivot  10 ; a rear frame  11 ; a swing arm  12  (as shown in  FIG. 1  only); a power transmission  13  (as shown in  FIG. 1  only); a seat  14 ; a rear suspension  15 ; an exhaust pipe  16 ; a muffler  17  (as shown in  FIG. 2  only); and a front cowl  50 . 
   With reference to  FIGS. 1 and 2 , the illustrated body frame  20  (see  FIG. 2 ) comprises left and right main frames that extend diagonally downward and rearward from a head pipe  21 . The head pipe  21  is positioned at a front end of the vehicle. Rear frames  11  are connected to the main frames  22 . In the illustrated construction, the rear frames  11  extend rearward of a rearward portion of the main frames  22 . Swing arms  12  are connected to a lower portion of the main frames  22 . The swing arms  12  are connected so that the swing arms  12  can be pivoted vertically about an axis defined by a pivot  10 . A rear wheel  2  is supported by the swing arms  12 . Preferably, the rear wheel  2  rotates about a generally horizontal axis A1. A suitable rear suspension  15  is provided between the swing arms  12  and the rear frames  11 . Other frame and suspension constructions also can be used. 
   On the head pipe  21 , which is disposed at the front end of the body frame  20 , a handlebar  6  is pivotably supported. Below the handlebar  6 , front forks  5  are connected to the handlebar  6  such that the front forks  5  can be maneuvered by the handlebar  6 . The front wheel  1  is connected to lower portions of the front forks  5 . Preferably, the front wheel  1  rotates about a generally horizontal axis A 2 . 
   In one embodiment of the straddle type vehicle (e.g., motorcycle), an engine  3  is provided in a substantially longitudinally central portion and suspended from an engine suspension frame  23  provided on the lower side of and made integral with the main frame  22  of the body frame  20 . Other constructions also can be used. In one embodiment, the engine  3  is a parallel 4-cylinder engine that is transversely mounted. In this configuration, the engine  3  has a cylinder  3 A that is positioned generally above a crank case and that is slightly inclined. Because the engine  3  is mounted in this manner, the engine  3  is positioned generally below and between the left and right main frames  22 . 
   Multiple exhaust pipes  16  are joined to an exhaust port that is positioned on a front side of the cylinder  3 A. From the exhaust ports, the exhaust pipes  16  extend rearward along an underside of the illustrated engine  3 . The exhaust pipes  16  merge and are connected to a muffler  17 . 
   In one embodiment, a radiator  4  is positioned at substantially the same vertical height as the cylinder  3 A. The radiator  4  also preferably is positioned generally forward of the engine  3  with an air passing surface facing in the forward direction. In other words, the surface through which air is introduced into the radiator  4  extends in a plane that is generally normal to a longitudinal direction of the vehicle. 
   A fan  4 A can be provided rearward of the radiator  4 . An air cleaner  8  and a fuel injection system  9  can be provided above the engine  3 . A fuel tank  7  can be provided rearward of the engine at a location generally above the main frame  22 . A seat  14  on which a rider can sit is placed on the rear frame  11  at a location generally rearward of the fuel tank  7 . Generally below the seat  14 , electrical equipment, such as a battery  18 A, a relay  18 B, and an ECU (engine control unit)  18 C can be positioned on the rear frame  11 . A power transmission system  13  can be positioned to the left of the rear portion of the vehicle body and the muffler  17  can be positioned to the right of the rear portion of the vehicle body. 
   With reference now to  FIGS. 6 through 13 , a front cowl  50  preferably extends from a location proximate an instrument panel (which is provided forward of the handlebar  6 ) to a location that is proximate the left and right sides of the engine  3 . In one embodiment, the left and right sides of the engine as well as the exhaust pipe  16  are substantially covered by the front cowl  50 . The front cowl  50  can be formed by a combination of an upper portion  51  and a lower portion  52 , both of which, in one embodiment, can be formed from a reinforced plastic material. The front cowl upper portion  51  and the front cowl lower portion  52  can be composed of other suitable materials as well. 
   With reference to  FIG. 7 , the front cowl upper portion  51  preferably is sized and configured to cover components that are positioned ahead of the handlebar  6 . The front cowl lower portion  52  preferably is sized and configured to cover the range from a lower edge portion of the front cowl upper portion  51  to the side portions of the engine  3 . As shown in  FIG. 6 , the front cowl  50  advantageously comprises a central port  66 . The central port  66  can be positioned at a central portion of a front wall of the front cowl  50 . In one configuration, the central port  66  is formed in the lower portion  52  of the front cowl. As shown in the illustrated embodiment, the central port  66  can be positioned in proximity to the front wheel  1 . Air traveling toward the radiator  4  is received from the central port  66  and the radiator  4  can be positioned rearward of the central port  66 . Thus, air traveling through the central port  66  can be directed toward the radiator  4 . 
   In one embodiment of the straddle type vehicle (e.g., motorcycle), left and right headlights  54  are positioned in the front cowl upper portion  51 . Preferably, the headlights  54  are mounted such that the front cowl upper portion  51  is generally streamlined as a whole. With reference to  FIG. 6 , an air intake port  55  through which air is drawn into the air cleaner  8  can be positioned generally between the left and right headlights  54 . A windscreen  56  preferably extends diagonally upward and rearward direction from the central upper portion of the front cowl upper portion  51 . The windscreen  56 , in one embodiment, covers the instrument panel from the front side. The windscreen  56  preferably is formed of a transparent resin. Recesses  57  preferably extend from the front side to the rear side of the front cowl upper portion  51  and can be provided along the longitudinal curves of the two side surfaces. The recesses  57  desirably are positioned lower than the headlamps  54  and higher than the radiator  4 . 
   As shown in  FIG. 6 , the front cowl lower portion  52  can include a lower cowl  61  (as described below in connection with  FIGS. 10 and 11 ) sized and configured to cover both sides of the radiator  4  and the exhaust pipe  16 . The illustrated front cowl lower portion  52  also comprises a hooked upper cowl  62  (as described below in connection with  FIG. 12 ) that is spaced from the lower cowl  61  and that extends along the main frame  22 . The hooked upper cowl  62  preferably is connected at a front end to the front cowl upper portion  51 . In some configurations, the front cowl upper portion  51  and the upper cowl  62  can be integrally formed. Knife-shaped panel type middle cowls  63  (as described below in connection with  FIG. 13 ) can be provided between the lower cowl  61  and the upper cowl  62 . Preferably, spaces are defined between the lower cowl  61  and the upper cowl  62  when the middle cowls  63  are removed. The spaces can be sized and configured to expose large portions of the side surfaces of the engine  3  and a portion of each of the side surfaces of the radiator  4 . 
   The middle cowls  63  preferably are sized to be not large enough to cover the open portion as a whole between the lower cowl  61  and upper cowl  62 . The middle cowls  63  extend generally longitudinally such that they vertically divide the air discharge ports for air being exhausted from the radiator. In one embodiment, between the middle cowls  63  and the lower cowl  61 , a lower air discharge port  71  is defined. The lower discharge port  71  discharges air exhausted from the radiator  4 . In addition, between the middle cowls  63  and the upper cowl  62 , an upper air discharge port  72  is defined. The upper air discharge port  72  discharges air exhausted from the radiator  4 . The upper air discharge port  72  is a discharge port mainly for the exhausted air that has passed through an upper portion  4 U of the radiator  4  while the lower air discharge port  71  is a discharge port mainly for the exhausted air that has passed through a lower portion  4 D of the radiator  4 . 
   As shown in  FIGS. 5 and 12 , the upper cowl  62  preferably is formed in the shape of a hook, as seen from a side elevational view, and is generally mountain-shaped in cross-section. The mountain-shaped cross-section comprises a ridge portion  62   a  and an inner inclined surface  62   b . Preferably, the inner inclined surface  62   b  extends at an angle relative to the ridge portion  62   a . At least a portion of the inner inclined surface  62   b  is positioned opposite to the middle cowls  63  and generally parallel with an upper edge of the middle cowl  63 . In this manner, the upper air discharge port  72  is seen with a larger opening in a side elevation view than the same port when viewed from a location diagonally above the discharge port  72 . Therefore, radiator exhaust air that travels diagonally upward passes through the upper air discharge port  72 . 
   The ridge portion  62   a  preferably is curved with the inner inclined surface  62   b  being on the inside of the curve defined by the ridge portion  62   a . Therefore, the bent portion of the inclined surface  62   b , which has an apex at the ridge portion  62   a , defines a valley-shaped terminal wall  62   c . The terminal wall  62   c  preferably is positioned along a rearward portion of the upper cowl  62 . More preferably, the terminal wall  62   c  is positioned ahead of the foot of a driver sitting on the seat (as shown in  FIG. 5 ). Since the inner inclined surface  62   b  comprises a hooked configuration, the upper cowl  62 , and the inclined surface  62   b  of the illustrated embodiment, defines a recess  62   d  recessed inward in the widthwise direction of the vehicle body relative to the balance of the upper cowl  62 . 
   With reference to  FIGS. 4 and 5 , the recess  57  defined in the lateral sides of the front cowl upper portion  51  are substantially connected to the inclined surface  62   b  and recess  62   d  of the upper cowl  62 . The recess  57 , together with the region defined between the inclined surface  62   b  and the middle cowls  63  define a vent passage  73 . More particularly, the region can be defined as the space formed by the inclined surfaces  62   b , the recess  62   d  and the middle cowls  63 . The region can be called an extension  73 E. The extension  73 E preferably is positioned above the upper air discharge port  72 . The extension  73 E elongates the vent passage  73  to define a longer air travel path than just the recess  57  alone. Thus, the vent passage  73  is positioned above the upper air discharge port  72  and the vent passage  73  is adapted to receive traveling outside air and pass such air rearward therethrough. At a rear end of the extension  73 E, diverter passages  73 F can be positioned to redirect the outside air flowing rearward in the vent passages  73  to an outward flow. 
   This diverted passage  73 F can be formed by the downwardly sloping inclined surface  62   b  and ridge portion  62   a  of the upper cowl  62 . The diverter passage  73 F also can extend in a horizontal section divergently in the rearward direction with the width of the diverter passages increasing in the lateral direction of the vehicle. In other words, the diverter passages  73 F become wider in a direction away from the center of the vehicle. Because the air enters the recesses  57  forcibly, the air flows along the vent passage  73  substantially linearly from the front side to the rear side. Therefore, the traveling air necessarily spreads outward in the transverse direction (i.e., the width) of the vehicle and flows rearward as the air is directed laterally outward by the diverter passage  73 F formed by the inclined surfaces  62   b  of the upper cowl  62 . In one preferred configuration, the diverter passages  73 F direct the airflow downward and outward to direct the air away from the legs of a rider. 
   The upper edges  63   a  of the side covers  63  preferably are fixed to upper side of the recesses  57  such that they project laterally outward. In this manner, the cross-section of the corresponding portions of the vent passage  73  is generally C-shaped. Therefore, the air flow can be focused and directed rearward without significant airflow bleed-off (i.e., significant air flow escaping from the passage  73 ). In one embodiment, the middle cowls  63  are fixed to the lower cowl  61  by screws. Any other suitable technique can be used. Because the vent passages  73  can be formed by combining the middle cowls  63  with the upper cowl  62  from the outer side so as to cover the lower portion of the upper cowl  62  (see  FIG. 9 ), forming of the vent passage  73  can be done with ease. 
   As shown in  FIGS. 1 ,  2 , and  7 , the outside air induction ducts  80  are provided inside of the lower cowl  61  and middle cowls  63  such that a forward facing intake port  67  opens toward the direction in which traveling air is introduced and such an outlet port is opened toward a space surrounded by the main frame  22 , the engine  3 , and the fuel tank  7 . At the rear of this space, air discharge passages for moving the air flow toward the rear are secured. These air discharge passages preferably are secured between the rear frames  11  and the swing arms  12  in a position that is lower than the pivot  10  such that the swing arms  12  can be freely swung in the vertical direction. 
   The intake ports  67  preferably are formed in side walls of the lower cowl  61  of the front cowl lower portion  52 . The intake ports  67  preferably communicate with the front end of the outside air induction ducts  80 . The intake ports  67  advantageously are positioned lower than the lower end of the radiator  4 . In one preferred configuration, the intake ports  67  are positioned in the side walls of the front cowl lower portion  52  at a location vertically below the lower side air discharge ports  71 . 
   The operation of the straddle type vehicle (e.g., motorcycle) will now be described. Some of the air passed through the radiator  4  during movement of the vehicle flows out upward or rearward from the upper air discharge ports  72  provided in side walls of the front cowl  50 . As the outside air flows relative to the straddle type vehicle, shown by arrows F in  FIGS. 1 through 5 , the traveling air F flows from front to rear at a high speed along in the vent passage  73 , which is positioned above the air discharge port  72 . The air flow F creates a pressure differential with the air flow having a lower pressure than the chamber in which the radiator is positioned. Because of the pressure difference, the heated exhaust air that passed through the radiator will be sucked through the upper air discharge port  72  to the outside of the vehicle. As a result, the heat in the front cowl  50  can be discharged efficiently to the outside of the vehicle. 
   Moreover, since the vent passage  73  extends in the longitudinal direction of the vehicle up to a position just above the upper air discharge port  72 , heated air that is passed through the radiator  4  can flow smoothly in the rearward direction. Because the diverter passages  73 F for inducing the air flowing rearward in the vent passages  73  outward are positioned at the rearward portions of the extensions  73 E of the vent passages  73 , the heated exhaust air from the radiator  4  can be diverted outward in positions in front of the legs of the driver. Therefore, the heated exhaust air is less likely to contact the legs of the driver, which results in a more comfortable riding experience. 
   In this straddle type vehicle (e.g., motorcycle), two vertically spaced ports (i.e., the lower air discharge port  71  and the upper air discharge port  72 ) for discharging the radiator-passed exhaust air are provided. As a result, even when a cooling operation is carried out solely by operation of the radiator fan  14 A, the hot air can be discharged smoothly. In addition, because the vent passages  73  mentioned above are formed in regions not occupied by the headlight  54  and the radiator  4 , a typically vacant space in the vehicle between the headlight  54  and the radiator  4  can be effectively utilized. 
   Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. For instance, it is possible to form any or all of the cowlings either integrally or to further segment the cowlings in to sub-cowlings that perform in the manners discussed herein. In other words, the upper cowling can be formed in multiple pieces in some embodiments relative to the constructions shown and described above. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims.