Patent Publication Number: US-2023140031-A1

Title: Sensor attachment structure for straddle-type vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on Japanese Patent Application No. 2021-180468 filed on Nov. 4, 2021, the contents of which are incorporated herein by way of reference. 
     TECHNICAL FIELD 
     The present invention relates to a sensor attachment structure for a straddle-type vehicle. 
     BACKGROUND 
     In a straddle-type vehicle, good traveling stability is obtained by traveling in a state where tires have high ground contact property with respect, to a road surface. Examples of a condition for improving the ground contact property of a tire include that the tire has an appropriate air pressure and that the tire has an appropriate temperature. Therefore, it is effective to monitor air pressure information and temperature information of the tire while the straddle-type vehicle is traveling. As such a straddle-type vehicle, a vehicle attached with a sensor unit that detects air pressure information and temperature information of a tire of a wheel, and transmits the air pressure information and the temperature information to a control device by wireless communication is known (for example, see Patent Literature 1). 
     Patent Literature 1: JP-A-2009-222458 
     Depending on the vehicle type, weight reduction of a wheel and wired connection of the sensor unit may be required. Since the sensor unit disclosed in Patent Literature 1 is attached to a rim of the wheel, a weight increase of the wheel is increased, and the sensor unit cannot be connected in a wired manner. Although it is conceivable to attach the sensor unit to a portion other than the wheel, depending on the layout, there is also a problem that traveling wind may hit the sensor unit and air resistance increases. 
     The present invention has been made in view of the above, and an object thereof is to provide a sensor attachment structure for a straddle-type vehicle that can reduce an increase in the weight of a wheel and can be compatible with wired connection, and further reduce an increase in air resistance. 
     SUMMARY 
     A sensor attachment structure for a straddle-type vehicle according to an aspect of the present invention includes: a sensor unit including a sensor configured to detect a state of a tire; and a fender formed along an outer surface shape of an upper portion of the tire. The sensor unit is attached to a rear portion of the fender and faces the tire, thereby solving the above-described problem. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a left side view of a front portion of a vehicle according to the present embodiment. 
         FIG.  2    is a left side view of periphery of a front wheel according to the present embodiment. 
         FIG.  3    is a top view of the periphery of the front wheel according to the present embodiment. 
         FIG.  4    is a rear view of the periphery of the front wheel according to the present embodiment. 
         FIG.  5    is a sectional view of the periphery of the front wheel of  FIG.  2    taken along a line A-A. 
         FIG.  6    is a sectional view of the periphery of the front wheel of  FIG.  3    taken along a line B-B. 
         FIG.  7    is a diagram showing a flow of air around the front wheel according to the present embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A sensor attachment structure for a straddle-type vehicle according to an aspect of the present invention is a structure for attaching a sensor unit to a fender. The sensor unit is provided with a sensor for detecting a state of a tire, and the tender is formed along an outer surface shape of an upper portion of the tire. Since the sensor unit is attached to the fender, an increase in the weight of the wheel can be reduced, and the sensor unit can be made compatible with the wired connection. In addition, the sensor unit is attached to a rear portion of the fender where traveling wind hardly hits, so that the traveling wind is less likely to hit the sensor unit, and an increase in air resistance is reduced. 
     [Embodiment] 
     Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings.  FIG.  1    is a left side view of a front portion of a vehicle according to the present embodiment. In the following drawings, an arrow FR indicates a vehicle front side, an arrow RE indicates a vehicle rear side, an arrow L indicates a vehicle left side, and an arrow R indicates a vehicle right side. 
     As shown in  FIG.  1   , a head pipe  11  is formed in a front portion of a vehicle frame  10  of a straddle-type vehicle. A front fork  15  is steerably supported by the head pipe  11  via a steering shaft (not shown). An axle bracket  17  is provided at a lower portion of a pair of fork tubes  16  of the front fork  15 , and a front wheel  21  is rotatably supported by the axle bracket  17  via an axle  18 . The front wheel  21  is formed by attaching a tire  23  to an outer peripheral surface of a wheel  22 . A cast wheel in which a rim, a hub, and a spoke are integrally molded is used for the wheel  22  of the front wheel  21 . 
     In order to confirm the ground contact property of the tire  23  of the front wheel  21 , it is desired to detect a temperature of the tire  23  by a sensor unit  30 . A sensor unit of a wireless type is provided on the wheel  22 , but the sensor unit  30  of a wired type is employed for a model in which weight reduction of the front wheel  21  is desired, a model which is not compatible with wireless communication, or the like. The sensor unit  30  of a wired type is attached to a front fender (fender)  25 , but the air resistance increases when traveling wind hits the sensor unit  30 . Therefore, in the straddle-type vehicle of the present embodiment, an attachment structure suitable for the sensor unit  30  of a wired type is adopted. 
     A sensor attachment structure for a straddle-type vehicle will be described with reference to  FIGS.  2  to  6   .  FIG.  2    is a left side view of periphery of a front wheel according to the present embodiment.  FIG.  3    is a top view of the periphery of the front wheel according to the present embodiment.  FIG.  4    is a rear view of the periphery of the front wheel according to the present embodiment.  FIG.  5    is a sectional view of the periphery of the front wheel of  FIG.  2    taken along a line A-A.  FIG.  6    is a sectional view of the periphery of the front wheel of  FIG.  3    taken along a line B-B. 
     As shown in  FIGS.  2  to  4   , the front fender  25  made of resin is provided at a lower portion of the front fork  15 . The front fender  25  is formed along an outer surface shape of an upper portion of the tire  23 , and the front fender  25  suppresses the intrusion of a foreign matter into a mud guard and the front wheel  21 . The front fender  25  includes a fender upper portion  26  that covers the upper portion of the tire  23 , and fender side portions  27  that extend downward from left and right side edges of the fender upper portion  26 . The fender upper portion  26  is formed so as to cover the tire  23  from above, and the fender side portion  27  bulge outward in a vehicle width direction so as to cover a lower portion of the fork tube  16  from a front side. 
     The sensor unit  30  is attached to a rear portion of the fender upper portion  26  so as to face the tire  23 . The sensor unit  30  is provided with a plurality of (three in the present embodiment) temperature sensors  31  (see  FIG.  6   ) as sensors for detecting a state of the tire  23 . A temperature of the tire  23  is detected in a non-contact manner during traveling by the plurality of temperature sensors  31 . A wire  32  extends from the sensor unit  30  toward a control device (not shown), and a detected temperature is transmitted from the plurality of temperature sensors  31  to the control device through the wire  32 . As described above, in the straddle-type vehicle of the present embodiment, the sensor unit  30  of a wired type is attached to the front fender  25 . 
     An upper surface of the fender upper portion  26  is curved in an arch shape in a side view, and a front portion and the rear portion of the fender upper portion  26  are lower than a central portion of the fender upper portion  26 . Although traveling wind from the front side easily hits the front portion and the central portion of the fender upper portion  26 , the traveling wind from the front side is less likely to hit the rear portion of the fender upper portion  26 . At the rear portion of the fender upper portion  26 , the sensor unit  30  is positioned below an upper end of the fender upper portion  26 , that is, below a straight line L 1  extending forward and rearward from the upper end of the fender upper portion  26 . Therefore, the traveling wind from the front side is less likely to hit the sensor unit  30 , and an increase in air resistance is reduced. 
     The tender side portions  27  protrude further outward in the vehicle width direction than the left and right side edges of the fender upper portion  26 , and an upper surface of the fender side portion  27  connected to the fender upper portion  26  is formed stepwise in the vehicle width direction (see particularly  FIG.  3   ). The upper surface of the fender side portion  27  is increased in height rearward, and a wind guide surface  28  for guiding traveling wind obliquely upward toward a rear side is formed by the upper surface of the fender side portion  27 . The sensor unit  30  is located below an extension line L 2  obtained by extending an upper edge of the wind guide surface  28  toward the rear side in a side view. Therefore, the traveling wind guided by the wind guide surface  28  of the fender side portion  27  is less likely to hit the sensor unit  30 , and an increase in the air resistance is reduced. 
     As shown in  FIGS.  5  and  6   , the plurality of temperature sensors  31  of the sensor unit  30  are fixed to an inside of a sensor cover  41  via a sensor bracket  35 . The sensor bracket  35  is formed in a plate shape elongated in the vehicle width direction, and the plurality of temperature sensors  31  are arranged in the vehicle width direction on a lower surface of the sensor bracket  35 . Portions of the fender upper portion  26  that are corresponding to the plurality of temperature sensors  31  are opened, and a detection surface of each temperature sensor  31  is exposed from the corresponding opening of the fender upper portion  26 . For example, an infrared temperature sensor that detects a surface temperature of the tire  23  based on an amount of infrared radiation emitted from the tire  23  is used as the plurality of temperature sensors  31 . 
     The plurality of temperature sensors  31  and the sensor bracket  35  are covered by the sensor cover  41  from above. A front portion of the sensor cover  41  is formed along an outer surface of the fender upper portion  26 , and a rear portion of the sensor cover  41  partially bulges away from the outer surface of the fender upper portion  26 . A first bulging portion  42  is formed along the vehicle width direction at the rear portion of the sensor cover  41 , and second bulging portions  43  (in particular, see  FIG.  4   ) are formed on the rear side of the first bulging portion  42  at two locations on the left and right avoiding the center in the vehicle width direction. The second bulging portion  43  bulges more than the first bulging portion  42 . The sensor bracket  35  and the plurality of temperature sensors  31  are accommodated inside the first bulging portion  42 , and the wire  32  and a signal processing unit  33  (see  FIG.  2   ) are accommodated inside the second bulging portion  43 . 
     A front fixing portion  44  that is in contact with the outer surface of the fender upper portion  26  as a whole is formed in the front portion of the sensor cover  41 . A rear fixing portion  45  that is in contact with the outer surface of the fender upper portion  26  is formed at the center in the vehicle width direction at the rear side of the first bulging portion  42 . The front fixing portion  44  at the front side of the plurality of temperature sensors  31  and the rear fixing portion  45  at the rear side of the temperature sensor  31  are fixed to the fender upper portion  26 , so that the sensor unit  30  is stably attached to the front fender  25 . Since the plurality of temperature sensors  31  are fixed to the front fender  25  via the sensor cover  41 , a wide fixing surface between the front fender  25  and the sensor cover  41  is secured. 
     The sensor cover  41  is entirely formed along the outer surface of the fender upper portion  26 . Although the first bulging portion  42  is connected to the rear side of the front fixing portion  44 , a stepped surface  46  between the front fixing portion  44  and the first bulging portion  42  is inclined so as to guide the traveling wind to the rear side in front of the temperature sensor  31 . Although the second bulging portion  43  is connected to the rear side of the first bulging portion  42 , a stepped surface  47  between the first and second bulging portions  42 ,  43  is inclined so as to guide the traveling wind to the rear side behind the temperature sensor  31 . As described above, even if the first and second bulging portions  42 ,  43  are formed in the sensor cover  41 , the traveling wind can flow smoothly to the rear side along the sensor cover  41  by the stepped surfaces  46 ,  47 . 
     A flow of air around the front wheel will be described with reference to  FIG.  7   .  FIG.  7    is a diagram showing the flow of air around the front wheel according to the present embodiment. 
     As shown in  FIG.  7   , traveling wind F 1 , F 2  flows along an outer surface of the front fender  25  during traveling of the straddle-type vehicle in a side view. The traveling wind F 1  flows along the outer surface of the fender upper portion  26  from a front edge to the upper end of the fender upper portion  26 . The traveling wind F 1  partially peels off in the vicinity of the upper end of the fender upper portion  26 , and only a part of the traveling wind F 1  blows against the sensor unit  30  on a rear edge side of the fender upper portion  26 . The sensor cover  41  of the sensor unit  30  has a shape along the outer surface of the fender upper portion  26 , and the stepped surfaces  46  and  47  at bulging portions of the sensor cover  41  are inclined surfaces, so that the traveling wind F 1  flows smoothly to the rear side and an increase in the air resistance is reduced. 
     As described above, the upper surface of the fender side portion  27  serves as the wind guide surface  28  that guides the traveling wind obliquely rearward, and the traveling wind F 2  flows rearward along the wind guide surface  28  of the fender side portion  27 . The fork tube  16  is positioned on the rear side of the wind guide surface  28 , and the traveling wind F 2  which passed through the wind guide surface  2 $ passes through an inside of the fork tube  16 . As a result, the traveling wind F 2  passes above the sensor unit  30 , and the traveling wind flows to the rear side of the front fender  25  Since the sensor unit  30  is out of the flow of the traveling wind F 2 , the traveling wind F 2  is less likely to hit the sensor unit  30 , and an increase in the air resistance is reduced. 
     As described above, according to the present embodiment, the sensor unit  30  is attached to the front fender  25 , so that an increase in the weight of the front wheel  21  can be reduced, and the sensor unit  30  can be made compatible with the wired connection. In addition, the sensor unit  30  is attached to the rear portion of the front fender  25  where traveling wind hardly hits, so that the traveling wind is less likely to hit the sensor unit  30 , and an increase in the air resistance is reduced. 
     In the present embodiment, the temperature sensor is illustrated as an example of the sensor, but the sensor is not particularly limited as long as it is a sensor capable of detecting a state of the tire. 
     Further, in the present embodiment, the sensor is attached to the front fender, but the sensor may be attached to a rear fender with a similar configuration. 
     Further, in the present embodiment, the front tender has the fender upper portion and the fender side portions, but the front fender may have at least the fender upper portion 
     Further, in the present embodiment, the sensor unit is positioned below the upper end of the front fender, but the attachment position of the sensor unit is not particularly limited as long as the sensor unit is at the rear portion of the front fender. 
     Further, in the present embodiment, the sensor unit includes a plurality of sensors, but the sensor unit may include at least one sensor. 
     Further, in the present embodiment, the plurality of sensors are fixed to the sensor cover via the sensor bracket, but the plurality of sensors may be directly fixed to the sensor cover. 
     Further, in the present embodiment, the sensor cover is formed along the outer surface of the front tender, but the shape of the sensor cover is not particularly limited. 
     In addition, the straddle-type vehicle is not limited to a general vehicle on which a rider rides in a posture of straddling a seat, and also includes a small-sized scooter type vehicle on which a rider rides without straddling a seat. 
     As described above, a sensor attachment structure for a straddle-type vehicle according to the present embodiment includes: a sensor unit ( 30 ) including a sensor (temperature sensor  31 ) configured to detect a state of a tire ( 23 ); and a fender (front fender  25 ) formed along an outer surface shape of an upper portion of the tire. The sensor unit is attached to a rear portion of the fender and faces the tire. According to such a configuration, the sensor unit is attached to the fender, so that an increase in the weight of the wheel can be reduced, and the sensor unit can be made compatible with the wired connection. In addition, the sensor unit is attached to a rear portion of the tender where traveling wind hardly hits, so that the traveling wind is less likely to hit the sensor unit, and an increase in air resistance is reduced. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the sensor unit is located below an upper end of the fender. According to such a configuration, the traveling wind from the front side is less likely to hit the sensor unit, and an increase in the air resistance is reduced. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the fender includes a fender upper portion ( 26 ) covering the upper portion of the tire and fender side portions ( 27 ) extending downward from both side edges of the fender upper portion The fender side portions are each formed with an wind guide surface ( 28 ) that is configured to guide traveling wind obliquely upward toward a rear side, and the sensor unit is located below an extension line (L 2 ) of the wind guide surface in a side view. According to such a configuration, the traveling wind guided by the wind guide surface of the fender side portion is less likely to hit the sensor unit, and an increase in the air resistance is reduced. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the sensor unit includes a sensor cover ( 41 ) that covers the sensor from above, and the sensor cover is formed along an outer surface of the fender. According to such a configuration, the traveling wind smoothly flows to the rear side along the sensor cover, and an increase in the air resistance is reduced. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the sensor cover is formed with a stepped surface ( 46 ) inclined so as to guide traveling wind to a rear side in front of the sensor. According to such a configuration, the traveling wind can flow more smoothly to the rear side along the sensor cover. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the sensor is a plurality of sensors arranged in a vehicle width direction, and the sensor unit includes a sensor bracket ( 35 ) that supports the plurality of sensors. According to such a configuration, the support rigidity of the plurality of sensors can be increased by the sensor bracket. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the sensor cover covers the plurality of sensors and the sensor bracket from above, and the plurality of sensors are fixed to the sensor cover via the sensor bracket. According to such a configuration, the plurality of sensors are fixed to the fender via the sensor cover, so that a wide fixing surface between the fender and the sensor cover can be secured. 
     In the sensor attachment structure for a straddle-type vehicle according to the present embodiment, the sensor cover is fixed to the fender at a front side and a rear side of the sensor. According to such a configuration, the sensor unit can be stably attached to the fender. 
     Although the present embodiment has been described, the above-described embodiment and a modification may be combined in whole or in part as another embodiment. 
     The technique of the present invention is not limited to the above-described embodiment, and various changes, substitutions and modifications may be made without departing from the spirit of the technical concept of the present invention. The present invention may be implemented by other methods as long as the technical concept can be implemented by the methods through advance of the technique or other derivative techniques. Accordingly, the claims cover all embodiments that may be included within the scope of the technical concept.