Patent Publication Number: US-11022032-B2

Title: Engine

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an engine, including: a cylinder head that forms an intake port continuing to a combustion chamber; a throttle body that is joined to the intake port, and that adjusts a degree of an opening of an intake passage by rotating a throttle vale around a rotation axis of a valve shaft, the throttle vale being fixed to the valve shaft; and a case that stores a drive member and supports a drive motor, the drive member being fixed to the valve shaft, the drive motor generating a drive force that is transmitted to the drive member. 
     Description of the Related Art 
     Japanese Patent Application Laid-open No. 2017-194052 discloses a throttle body supporting a throttle valve that rotates around the axis of a valve shaft according to the drive force of an electric motor. The throttle valve adjusts the opening area of the intake passage. Between the throttle valve and the combustion chamber, a pressure sensor detecting pressure of the intake passage is disposed. 
     In Japanese Patent Application Laid-open No. 2017-194052, although it is suggested that increase of the engine output and improvement of the combustion stability in low load operation are achieved when the volume of the intake passage is reduced between the throttle valve and the combustion chamber, even when reduction of the volume of the intake passage is hard between the throttle valve and the combustion chamber, by adjusting the degree of opening of the throttle valve according to the pressure of the intake passage, both of increase of the engine output and the combustion stability in low load operation are achieved. An art for reducing the volume of the intake passage between the throttle valve and the combustion chamber has not been disclosed in concrete terms. 
     SUMMARY OF THE INVENTION 
     The present invention has been achieved under the circumstance described above, and its object is to provide an engine capable of reducing the volume of the intake passage between the throttle valve and the combustion chamber. 
     In order to achieve the object, according to a first aspect of the present invention, there is provided an engine, comprising: a cylinder head that forms an intake port connected to a combustion chamber; a throttle body that is joined to the intake port and adjusts a degree of an opening of an intake passage by rotating a throttle vale around a rotation axis of a valve shaft, the throttle vale being fixed to the valve shaft; and a case that stores a drive member and supports a drive motor, the drive member being fixed to the valve shaft, the drive motor generating a drive force that is transmitted to the drive member, wherein the case overlaps with the intake port as seen in a side view. 
     With the first aspect, in operation of the throttle valve, the drive member is displaced around the rotation axis of the valve shaft. The case has an extent that does not interfere with the drive member at the time of displacement of the drive member. Meanwhile, since the case overlaps with the intake port as seen in a side view, the throttle valve can approach the intake port as much as possible. Thus, the volume of the intake passage can be reduced from the downstream of the throttle valve to the combustion chamber. As a result, the intake efficiency improves. 
     According to a second aspect of the present invention, in addition to the first aspect, there is provided the engine, further comprising: a first gear that is attached to a first shaft, engages with the drive member, rotates around an axis of the first shaft, and drives the valve shaft; and a second gear that is attached to a second shaft, engages with the first gear and the drive motor, rotates around an axis of the second shaft, and transmits a drive force from the drive motor to the first gear. 
     With the second aspect, the first gear of the first shaft and the second gear of the second shaft configure a deceleration mechanism between the drive member and the drive motor. Since the deceleration mechanism is disposed between the drive member and the drive motor, the drive motor can get away from the intake port. As a result, interference of the drive motor and the intake port can be avoided. 
     According to a third aspect of the present invention, in addition to the second aspect, a drive shaft of the drive motor is positioned on a cylinder head side of an imaginary plane that includes an outer end of the intake port. 
     With the third aspect, since the drive motor is disposed at a position close to the cylinder head, the engine can be formed compact. Also, since the drive motor is disposed in a dead space around the cylinder head, the space around the cylinder head can be utilized efficiently. 
     According to a fourth aspect of the present invention, in addition to the third aspect, the second gear is positioned at least partially on the cylinder head side of the imaginary plane including the outer end. 
     With the fourth aspect, since the second gear of the deceleration mechanism is disposed at a position close to the cylinder head, the drive motor can get access to the cylinder head more closely, and the engine can be formed more compact. 
     According to a fifth aspect of the present invention, in addition to the fourth aspect, the first gear is positioned at least partially on the cylinder head side of the imaginary plane including the outer end. 
     With the fifth aspect, since the first gear of the deceleration mechanism is disposed at a position close to the cylinder head, the drive motor can get access to the cylinder head more closely, and the engine can be formed more compact. 
     According to a sixth aspect of the present invention, in addition any one of the second aspect to the fifth aspect, the case stores the first gear and the second gear, and at least a part of the case is positioned on the cylinder block side of an imaginary plane that includes a mating surface of the cylinder head and the cylinder block. 
     With the sixth aspect, since the case that stores the drive member of the valve shaft, the first gear, and the second gear is disposed in a dead space around the cylinder head, the space around the cylinder head can be utilized efficiently. 
     The above and other objects, characteristics and advantages of the present invention will be clear from detailed descriptions of the preferred embodiment which will be provided below while referring to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view that schematically shows an overall configuration of a two-wheeled motor vehicle according to an embodiment. 
         FIG. 2  is a side view that schematically shows an overall configuration of the two-wheeled motor vehicle in a state where a body cover is detached. 
         FIG. 3  is a view that schematically shows a configuration of an engine and an air cleaner box observed in a vertical section orthogonal to the rotation axis of the engine. 
         FIG. 4  is an enlarged top view of a throttle body. 
         FIG. 5  is an enlarged side view that schematically shows a configuration of a deceleration mechanism interposed between the valve shaft of a throttle valve and a drive motor. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, an embodiment of the present invention will be explained referring to the attached drawings. Here, directions of up, down, front, rear, left, and right of the vehicle body are to be defined based on the visual line of a rider riding the two-wheeled motor vehicle. 
       FIG. 1  schematically shows an overall image of a two-wheeled motor vehicle  11  that is a saddle riding vehicle according to an embodiment of the present invention. The two-wheeled motor vehicle  11  includes a body frame  12  and a body cover  13  that is mounted on the body frame  12 . The body cover  13  includes a front cowl  14  and a tank cover  17 , the front cowl  14  covering the body frame  12  from the front, the tank cover  17  continuing to the front from the outer surface of a fuel tank  15  and being connected to a riding seat  16  behind the fuel tank  15 . The fuel is stored in the fuel tank  15 . In driving the two-wheeled motor vehicle  11 , the rider straddles the riding seat  16 . 
     The body frame  12  includes a head pipe  18 , a pair of left and right main frames  21 , a down frame  22 , and left and right seat frames  23 , the main frames  21  extending downward to the rear from the head pipe  18  and including a pivot frame  19  at the rear lower end, the down frame  22  extending downward from the head pipe  18  at a position below the main frames  21  and being integrated with the main frames  21 , the seat frames  23  extending upward to the rear from a curved region  21   a  of the main frame  21  and configuring a truss structure. The riding seat  16  is supported by the seat frames  23 . 
     A front fork  24  is steerably supported by the head pipe  18 . A front wheel WF is supported by the front fork  24  so as to be rotatable around an axle  25 . A steering handlebar  26  is joined to the upper end of the front fork  24 . The rider holds grips at the left and right ends of the steering handlebar  26  in driving the two-wheeled motor vehicle  11 . 
     A swing arm  28  is connected to the body frame  12  at a rear part of the vehicle so as to be capable of swinging in the up-down direction around a pivot  27 . A rear wheel WR is supported by the rear end of the swing arm  28  so as to be rotatable around an axle  29 . An engine  31  is mounted on the body frame  12  between the front wheel WF and the rear wheel WR, the engine  31  generating power that is transmitted to the rear wheel WR. The engine  31  is connected to and supported by the down frame  22  and the main frames  21 . The power of the engine  31  is transmitted to the rear wheel WR through a transmission device. 
     As shown in  FIG. 2 , the engine body of the engine  31  includes a crankcase  33 , a cylinder block  34 , a cylinder head  35 , and a head cover  36 , the crankcase  33  including engine hangers  32   a ,  32   b  at the upper end and the lower end of the rear wall and outputting power around a rotation axis Rx, the engine hangers  32   a ,  32   b  being connected to the main frames  21 , the cylinder block  34  being joined to the front portion of the crankcase  33  from above and having a cylinder axis C that is positioned within a vertical plane orthogonal to the rotation axis Rx and stands up with respect to a horizontal plane, the cylinder head  35  being joined to the upper end of the cylinder block  34 , including an engine hanger  32   c  in the front wall, and supporting a valve train, the engine hanger  32   c  being connected to the down frame  22 , the head cover  36  being joined to the upper end of the cylinder head  35  and covering the valve train on the cylinder head  35 . Here, in the cylinder block  34 , four cylinders are disposed in series in the vehicle width direction determined by the rotation axis Rx that is parallel to the axle  29 . 
     To the cylinder head  35 , an intake device  38  and an exhaust device  41  are connected, the intake device  38  spraying fuel to the air that is purified by an air cleaner  37 , generating an air-fuel mixture, and supplying the air-fuel mixture to the combustion chamber that is covered by the cylinder head  35 , the exhaust device  41  purifying exhaust gas after combustion by a catalyst  39  and discharging the exhaust gas to the rear of the vehicle body while lowering the temperature of the exhaust gas, the exhaust gas being discharged from the combustion chamber. The exhaust device  41  includes an exhaust pipe  42  that passes under the crankcase  33 , extends along a lateral side of the rear wheel WR, and supports the catalyst  39  below the crankcase  33 . 
     The air cleaner  37  includes an air cleaner box  47  that is joined to a throttle body  45  and takes in travelling air from an air duct  46  that opens in front of the head pipe  18 . The air cleaner  37  takes in the travelling air into the air cleaner box  47  for purification, and delivers the purified air to the engine  31 . The air cleaner box  47  is covered by the fuel tank  15  from the rear. 
     As shown in  FIG. 3 , a cylinder  52  is defined in the cylinder block  34 , the cylinder  52  guiding a linear reciprocating motion of a piston  51  along the cylinder axis C. A combustion chamber  53  is formed between the piston  51  and the cylinder head  35 . To the combustion chamber  53 , a pair of intake ports  54   a  (only one is illustrated) and a pair of exhaust ports  54   b  (only one is illustrated) are connected, the pair of intake ports  54   a  and the pair of exhaust ports  54   b  opening at the ceiling of the combustion chamber  53 . By the cylinder head  35 , intake valves  55   a  and exhaust valves  55   b  are supported so as to be displaced in the axial direction, the intake valves  55   a  opening/closing an opening of each of the intake ports  54   a , the exhaust valves  55   b  opening/closing an opening of each of the exhaust ports  54   b.    
     The throttle body  45  is joined to the cylinder head  35 . By the throttle body  45 , a valve shaft  56  is supported so as to be rotatable around a rotation axis Vx. A throttle valve  57  is fixed to the valve shaft  56 . The throttle valve  57  adjusts the degree of opening of an intake passage  45   a  inside the throttle body  45  according to the rotation around the rotation axis Vx. Each of the intake passages  45   a  is connected to two pieces of the intake ports  54   a  for each of the cylinders  52 . 
     To the throttle body  45 , a funnel  58  is joined for each of the cylinders  52 . The funnel  58  penetrates the bottom wall of the air cleaner box  47  that is laid over the throttle body  45 , and protrudes to a clean chamber  61  inside the air cleaner box  47 . The space inside the air cleaner box  47  is divided into a dirty chamber  62  on the front side and the clean chamber  61  on the rear side by an air cleaner element  63 , the dirty chamber  62  being connected to the air duct  46  and introducing the travelling air from the air duct  46 . The air inside the dirty chamber  62  is filtered by the air cleaner element  63 , and flows in to the clean chamber  61 . The purified air flows in from the funnel  58  to the intake ports  54   a  of the cylinder head  35  through the intake passage  45   a  inside the throttle body  45 . 
     The intake device  38  includes a fuel supply device  64  that sprays fuel to the air purified by the air cleaner  37 . The fuel supply device  64  includes an upper injector  65 , a first fuel supply pipe  66 , a main injector  67 , and a second fuel supply pipe  68 , the upper injector  65  being incorporated into the upper wall of the air cleaner box  47  for each of the cylinders  52 , the first fuel supply pipe  66  extending linearly in the vehicle width direction above the air cleaner box  47  and supplying the fuel to each of the upper injectors  65  from a branch pipe corresponding to each of the upper injectors  65 , the main injector  67  being incorporated into the throttle body  45  for each of the cylinders  52 , the second fuel supply pipe  68  extending linearly in the vehicle width direction behind the throttle body  45  and supplying the fuel to each of the main injectors  67  from a branch pipe corresponding to each of the main injectors  67 . 
     Each of the upper injectors  65  injects the fuel downward toward the funnel  58 . In a low rotation range of the engine  31 , the fuel is injected from the main injector  67  in the intake passage  45   a  inside the throttle body  45 . In a high rotation range of the engine  31 , the fuel is injected from the upper injector  65  inside the clean chamber  61 , and the mixing ratio is adjusted by the fuel injected from the main injector  67 . 
     As shown in  FIG. 4 , in a space between the two center intake passages  45   a , a case  71  is disposed, the case  71  supporting a drive motor  69  below the second fuel supply pipe  68 , the drive motor  69  generating drive power that is transmitted to the valve shaft  56 . The case  71  includes a first body  71   a  and a second body  71   b , the first body  71   a  being formed integrally with the throttle body  45  and being joined to the casing of the drive motor  69 , the second body  71   b  being fastened to the first body  71   a  through a mating surface by fastening members, the mating surface being orthogonal to the rotation axis Vx of the valve shaft  56 . The fastening members may be bolts screwed into female screw holes that are bored in a boss of the first body  71   a  for example. A storage space is defined in the inside of both of the first body  71   a  and the second body  71   b.    
     As shown in  FIG. 5 , in the case  71 , a sector gear (drive member)  72 , a first gear  74 , a second gear  76 , a third gear  77 , and a drive gear  78  are stored, the sector gear  72  being fixed to the valve shaft  56 , the first gear  74  being attached to a first shaft  73  and engaging with the sector gear  72 , the first shaft  73  having an axis Gx that is parallel to the rotation axis Vx of the valve shaft  56 , the second gear  76  being attached to a second shaft  75  and engaging with the first gear  74 , the second shaft  75  having an axis Jx that is parallel to the rotation axis Vx of the valve shaft  56 , the third gear  77  being integrated with the second gear  76  so as to be coaxial with the second gear  76  and having a larger diameter compared to the second gear  76 , the drive gear  78  being fixed to a drive shaft  69   a  of the drive motor  69  and engaging with the third gear  77 . When the drive shaft  69   a  of the drive motor  69  rotates, the rotational force of the drive shaft  69   a  is transmitted from the drive gear  78  to the third gear  77 . Since the third gear  77  is integrated with the second gear  76 , the rotational force of the third gear  77  causes rotation of the second gear  76  around the axis Jx of the second shaft  75 . The second gear  76  rotates around the axis Jx of the second shaft  75 , and transmits a drive force to the first gear  74 . Thus, the drive force is transmitted from the drive motor  69  to the first gear  74 . The first gear  74  rotates around the axis Gx of the first shaft  73 , rotates the sector gear  72 , and drives the valve shaft  56 . The case  71  defines a space having a circular plate shape extending to the outside of the sector gear  72  so as to be coaxial with the rotation axis of the sector gear  72 . 
     The case  71  includes a first outer wall  79   a  and a second outer wall  79   b , the first outer wall  79   a  having a cylindrical shape surrounding the moving route of the sector gear  72  that rotates around the rotation axis Vx, the second outer wall  79   b  continuing from the first outer wall  79   a  and having a squarish shape that surrounds the third gear  77 . The second outer wall  79   b  is disposed along the cylinder block  34  and the cylinder head  35 . The first gear  74  protrudes from a space surrounded by the second outer wall  79   b  toward a space surrounded by the first outer wall  79   a , and engages with the sector gear  72 . The first outer wall  79   a  is narrowed toward the second outer wall  79   b  while leaving the occupying spaces of the first gear  74  and the third gear  77 . The cylindrical shape of the first outer wall  79   a  is cut at the occupying space of the first gear  74 . 
     Here, the first outer wall  79   a  overlaps with the intake port  54   a  at least partially as seen in a side view of the vehicle body. In other words, the first outer wall  79   a  is positioned on the cylinder head side of an imaginary plane PL that includes the outer end of the intake port  54   a . Preferably, the drive shaft  69   a  of the drive motor  69  is positioned on the cylinder head side of the imaginary plane PL that includes the outer end of the intake port  54   a . In addition, the second gear  76  is positioned on the cylinder head side of the imaginary plane PL at least partially, the imaginary plane PL including the outer end of the intake port  54   a . To the extent possible, the first gear  74  is positioned on the cylinder head side of the imaginary plane PL at least partially, the imaginary plane PL including the outer end of the intake port  54   a . The second outer wall  79   b  is positioned on the cylinder block  34  side of an imaginary plane PQ that includes the mating surface of the cylinder head  35  and the cylinder block  34 . 
     Next, the operation of an internal combustion engine according to the present embodiment will be explained. When an accelerator is operated, the throttle valve  57  rotates according to the operation amount. The degree of opening of the intake passage  45   a  (intake path) is set according to the rotation of the throttle valve  57 . The air inside the clean chamber  61  flows in from the funnel  58  to the intake passage  45   a  and the intake port  54   a . The air-fuel mixture flows in to the combustion chamber  53  in response to an opening/closing operation of the intake valve  55   a . Linear reciprocating motion of the piston  51  is achieved in response to combustion of the air-fuel mixture inside the combustion chamber  53 . 
     When the throttle valve  57  rotates, the operation amount of the accelerator is detected. A detection signal determining the operation amount is fed to an ECU (electronic control unit). The ECU determines the rotation amount of the throttle valve  57  according to a predetermined correspondence relation. A control signal determining the rotation amount is fed to the drive motor  69 . The drive motor  69  rotates the drive shaft  69   a  by the rotation amount designated by the control signal. Rotation of the drive shaft  69   a  is transmitted from the drive gear  78  to the third gear  77 . Rotation of the third gear  77  causes rotation of the second gear  76  around the axis Jx of the second shaft  75 . The second gear  76  rotates around the axis Jx of the second shaft  75 , and transmits a drive force to the first gear  74 . Thus, the drive force is transmitted from the drive motor  69  to the first gear  74 . The first gear  74  rotates around the axis Gx of the first shaft  73 , rotates the sector gear  72 , and drives the valve shaft  56 . 
     In the engine  31  according to the present embodiment, when the throttle valve  57  is operated, the sector gear  72  is displaced around the rotation axis Vx of the valve shaft  56 . The case  71  has an extent that does not interfere with the sector gear  72  when the sector gear  72  is displaced. Meanwhile, the case  71  overlaps with the intake port  54   a  as seen in the side view. In other words, the outer wall of the case  71  surrounding the moving route of the sector gear  72  is positioned on the cylinder head  35  side of the imaginary plane PL that includes the outer end of the intake port  54   a . Therefore, the throttle valve  57  can approach the intake port  54   a  as much as possible. Thus, the volume of the intake passage can be reduced from the downstream of the throttle valve  57  to the combustion chamber  53 . As a result, the intake efficiency improves. 
     In the present embodiment, the engine  31  includes the first gear  74  and the second gear  76 , the first gear  74  being attached to the first shaft  73 , engaging with the sector gear  72 , rotating around the axis Gx of the first shaft  73 , and driving the valve shaft  56 , the second gear  76  being attached to the second shaft  75 , engaging with the first gear  74  and the drive gear  78  (through the third gear  77  that is integrated with the second gear  76 ), rotating around the axis Jx of the second shaft  75 , and transmitting the drive force from the drive motor  69  to the first gear  74 . The first gear  74  of the first shaft  73  and the second gear  76  (and the third gear) of the second shaft  75  configure a deceleration mechanism between the sector gear  72  and the drive motor  69 . Since the deceleration mechanism is disposed between the sector gear  72  and the drive motor  69 , the drive motor  69  gets away from the intake port  54   a . As a result, interference of the drive motor  69  and the intake port  54   a  can be avoided. 
     At this time, the drive shaft  69   a  of the drive motor  69  is positioned on the cylinder head  35  side of the imaginary plane PL that includes the outer end of the intake port  54   a . Therefore, since the drive motor  69  is disposed at a position close to the cylinder head  35 , the engine  31  can be formed compact. Also, since the drive motor  69  is disposed in a dead space around the cylinder head  35 , a space around the cylinder head  35  can be utilized efficiently. 
     In addition, the second gear  76  is positioned on the cylinder head  35  side of the imaginary plane PL at least partially, the imaginary plane PL including the outer end of the intake port  54   a . Since the second gear  76  of the deceleration mechanism is disposed at a position close to the cylinder head  35 , the drive motor  69  can get access to the cylinder head  35  more closely, and the engine  31  can be formed more compact. 
     Also, the first gear  74  is positioned on the cylinder head  35  side of the imaginary plane PL at least partially, the imaginary plane PL including the outer end of the intake port  54   a . Since the first gear  74  of the deceleration mechanism is disposed at a position close to the cylinder head  35 , the drive motor  69  can get access to the cylinder head  35  more closely, and the engine  31  can be formed more compact. 
     In the engine  31  according to the present embodiment, at least a part of the case  71  is positioned on the cylinder block  34  side of the imaginary plane PQ that includes the mating surface of the cylinder head  35  and the cylinder block  34 . Since the case  71  that stores the sector gear  72 , the first gear  74 , and the second gear  76  is disposed in a dead space around the cylinder head  35 , a space around the cylinder head  35  can be utilized efficiently.