JPWO2019049849A1 - Internal combustion engine - Google Patents

Abstract

The internal combustion engine is formed in an annular shape around a crank journal (51), and an annular plate (54) arranged on the outer surface of the crank web (53) and a crank journal continuously from the inner periphery of the annular plate (54). A cover plate (61) which is formed in an annular shape around (51) and forms an oil reservoir connected to an oil passage defined in the crank pin (52) between the outer surface of the crank web (53); , The detected body (55) that continuously projects from the outer circumference of the annular plate (54) and projects radially outward from the outer circumference of the crank web (53), and the detected body is faced to the trajectory of the detected body (55). And a detection sensor (58) that generates a pulse signal according to the movement of (55). This provides an internal combustion engine that can accurately detect the angular velocity of the crankshaft while avoiding an increase in the size of the engine body.

Description

The present invention is an annular plate formed around a crank journal and arranged on the outer surface of the crank web, and an annular plate formed around the crank journal continuously from the inner circumference of the annular plate. A cover plate that forms an oil sump connected to an oil passage that is defined in the crank pin, and an oil sump that is defined on the outer peripheral surface of the crank journal and is formed outside the bearing. The present invention relates to an internal combustion engine including a groove that forms an oil passage to be connected.

Patent Document 1 discloses a control device for an internal combustion engine. The internal combustion engine is composed of a single cylinder. The control device detects a misfire due to an over-lean air-fuel ratio in a single-cylinder internal combustion engine. The control device determines whether or not the amount of change in the angular velocity of the crankshaft during the front and rear combustion cycles exceeds a predetermined threshold value. When the number of times the amount of change exceeds the threshold value reaches a prescribed number of times within a preset number of cycles, the control device estimates a misfire of the internal combustion engine.

Japanese Patent Laid-Open No. 2014-199040 Japanese Unexamined Patent Publication No. 2014-43783

In detecting the angular velocity of the crankshaft, it is possible to detect the pulsar with an ACG (alternating current generator) connected to the end of the crankshaft. With this configuration, the angular velocity of the crankshaft can be detected without changing the design of the engine body. However, in a single-cylinder internal combustion engine, the vibration of the internal combustion engine is large, so that the pulsar cannot be accurately detected by the ACG. On the other hand, it is possible to attach a pulsar rotor to the crankshaft when detecting the angular velocity. However, when the pulsar rotor is attached to the crankshaft, the engine body inevitably becomes large in the axial direction of the crankshaft.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an internal combustion engine that can accurately detect the angular velocity of a crankshaft while avoiding an increase in the size of the engine body.

According to the first aspect of the present invention, a crank journal that is rotatably rotatable about an axis and is connected to a crankcase by a bearing, and an outer surface that is coupled to the crank journal, holds a crankpin, and faces the bearing. A crank web having, an annular plate formed around the crank journal, an annular plate disposed on an outer surface of the crank web, and an annular plate formed continuously around the crank journal from the inner circumference of the annular plate, Between the outer surface of the crank web and a cover plate that forms an oil sump connected to an oil passage defined in the crank pin, and an outer peripheral surface of the crank journal, the outer plate is provided outside the bearing. A groove that forms an oil passage that connects the oil sump to the formed oil chamber, a detected body that continuously extends from the outer circumference of the annular plate and projects radially outward from the outer circumference of the crank web, and the detected body An internal combustion engine is provided that includes a detection sensor that is opposed to the trajectory of the sensor and that generates a pulse signal according to the movement of the detected object.

According to the second aspect, in addition to the configuration of the first aspect, the internal combustion engine includes a cylinder block coupled to the crankcase, and a cylinder that is fitted in a cylinder bore of the cylinder block and guides a slide of a piston. A liner is provided, and a chip forming an escape of the detected object is formed in the cylinder liner.

According to the third aspect, in addition to the configuration of the first or second aspect, the internal combustion engine is screwed into the crank web, passes through an opening formed in the annular plate, and passes through the crank web into the annular shape. A fastening member that fixes the plate, and a restricting member that is fitted into the crank web and the annular plate to restrict the displacement of the annular plate along the surface of the crank web are provided.

According to the fourth side surface, in addition to the configuration of the third side surface, the crank web has an inner side surface on the back side of the outer side surface for projecting a balance weight at a position offset from a pin hole for receiving the crank pin. A fastening hole for receiving the fastening member is formed in the crank web at a position offset from the balance weight.

According to the fifth aspect, in addition to the configuration according to any one of the first to fourth aspects, the detected bodies are arranged in a ring around the rotation axis of the crankshaft, and are read by the detection sensor. A reluctor piece is provided, and the detection sensor is attached to the crankcase while being directed to the rotation axis of the crankshaft and inclined with respect to the vehicle vertical direction orthogonal to the ground when mounted on the vehicle.

According to the sixth aspect, in addition to the configuration of the fifth aspect, a link portion connected to the vehicle body frame in front of the rear wheel of the vehicle projects upward in the crankcase, and the detection sensor includes the link. It is arranged behind the section and in front of the rear wheel.

According to the seventh aspect, in addition to the configuration of the sixth aspect, the detection sensor is arranged offset in the vehicle width direction with respect to the center line of the rear wheel that is orthogonal to the axle of the rear wheel.

According to the first aspect, the lubricating oil introduced into the oil chamber flows along the outer circumference of the crank journal into the oil sump. The lubricating oil in the oil sump is retained in the oil sump by the centrifugal force of the crank web. The lubricating oil flows into the oil passage in the crank pin from the oil sump. From there, the lubricating oil is supplied to the contact area between the crankpin and the connecting rod. Lubrication is thus achieved in the contact area between the crankpin and the connecting rod. Since the object to be detected is provided on the outer periphery of the annular plate arranged on the outer surface of the crank web when forming the oil sump, no new member is added between the crank web and the bearing, and the crankshaft The axial enlargement of the internal combustion engine can be avoided. Moreover, since the existing parts are diverted, the angular velocity of the crankshaft can be detected without increasing the number of parts. The crank journal and the crank web form a crankshaft.

According to the second aspect, since the cylinder liner is chipped to avoid contact with the object to be detected, the crankshaft can be brought closer to the combustion chamber, and the internal combustion engine is prevented from increasing in size. You can

According to the third aspect, the restricting member restricts the circumferential displacement of the annular plate due to the rotation of the crankshaft along the surface of the crank web. As a result, the circumferential deviation between the crank web and the detected object can be avoided. The angular velocity of the crankshaft can be accurately detected.

According to the fourth aspect, when the annular plate is attached to the crank web, the fastening hole is provided at a position offset from the balance weight of the crank web, so that the shape of the balance weight of the crank web is not complicated and the crank web is not complicated. The object to be detected can be connected to the.

According to the fifth aspect, since the detection axis of the detection sensor points the rotation axis of the crankshaft, passage of the reluctor piece can be accurately detected. Further, since the detection sensor is attached to the clan case so as to be inclined from the vertical direction of the vehicle, it is possible to suppress the projection of the detection sensor in the height direction and to arrange the detection sensor without interfering with vehicle parts.

According to the sixth aspect, since the detection sensor is arranged between the link portion of the internal combustion engine and the rear wheel, it is possible to protect the front and the rear with vehicle parts without providing a protection cover for the detection sensor. ..

According to the seventh aspect, it is possible to make it difficult for water droplets splashed up along the center of the rear wheel in the vehicle width direction to hit the detection sensor.

FIG. 1 is a side view schematically showing the overall configuration of a scooter that is a specific example of a saddle-ride type vehicle according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of the internal combustion engine. FIG. 3 is an enlarged plan view of the crankcase observed from above. FIG. 4 is an enlarged sectional view of the crankshaft. 5(a) is an enlarged plan view of an annular plate and a cover plate having a detected object, (b) is an enlarged plan view of a first side of a crank web, and (c) is a second side of the crank web (a back side of the first side). ) Is an enlarged plan view of FIG. FIG. 6 is an enlarged partial sectional view of an annular plate and a cover plate showing a bolt. FIG. 7 is an enlarged partial sectional view of the annular plate and the cover plate showing the knock pin. FIG. 8 is an enlarged sectional view of a crankshaft according to another embodiment.

12... Body frame 33... Rotation axis 34 (of crankshaft) 34... Crank case 34a... Link 35... Cylinder block 45... Piston 46... Cylinder bore 47... Cylinder liner 49... Bearing 51... Crank journal 52... Crank pin 53... Crank Web 54... Annular plate 55... Detected object 55a... Reactor piece 56... Chip 58... Detection sensor (pulsar sensor)
61... Cover plate 62... Oil sump 63... Oil passage 66... Oil chamber 68... Groove 69... Pin hole 71... Balance weight 72... Fastening hole 73... Opening 74... Fastening member (bolt)
75... Restricting member (knock pin)
GD... Ground WR... Rear wheel

An embodiment of the present invention will be described below with reference to the accompanying drawings. In the following description, front and rear, left and right, and top and bottom refer to the directions seen by the occupant of the motorcycle.

FIG. 1 schematically shows the overall configuration of a scooter 11 which is a specific example of a saddle-ride type vehicle (motorcycle). The scooter 11 includes a body frame 12. The vehicle body frame 12 is formed of a head pipe 13, a down tube 14 extending downward from the head pipe 13, and a pair of left and right side frames 15 extending rearward from a lower end of the down tube 14. A front fork 16 and a steering handle 17 are rotatably supported by the head pipe 13. A front wheel WF is supported on the front fork 16 so as to be rotatable around an axle 18.

The side frame 15 includes a down frame portion 15a extending downward from the lower end of the down tube 14, a lower frame portion 15b extending from the rear end of the down frame portion 15a parallel to the ground, and a rear rising portion from the rear end of the lower frame portion 15b. The seat rail portion 15c extends and is arranged above the rear wheel WR. The occupant seat 19 is supported on the seat rail portion 15c.

The scooter 11 includes a vehicle body cover 21 that covers the vehicle body frame 12. In the vehicle body cover 21, a floor 22 is defined between the head pipe 13 and the occupant seat 19 on the lower frame portion 15b of the side frame 15. An occupant sitting on the occupant seat 19 can put his/her feet on the floor 22. A fuel tank 23 is supported on the lower frame portion 15b below the floor 22. A storage box 24 is supported by the seat rail portion 15c inside the vehicle body cover 21. The storage box 24 is opened and closed by the passenger seat 19.

A swing type power unit 25 is supported between the side frames 15 on the body frame 12 via a link mechanism 26 so as to be vertically swingable. The power unit 25 is connected to the internal combustion engine 27 that generates power based on the fuel supplied from the fuel tank 23, and transmits the power of the internal combustion engine 27 to the rear wheels WR with a linearly changing gear ratio. And a transmission device 28.

The rear wheel WR is rotatably supported around the axle 29 at the rear end of the power unit 25. A rear cushion unit 31 is attached between the rear end of the power unit 25 and the rear end of the seat rail portion 15c. The power unit 25 has a function of a suspension device that connects the rear wheels WR to the body frame 12 so as to be swingable.

The engine body 32 of the internal combustion engine 27 includes a crankcase 34 that accommodates a crankshaft, which will be described later, rotatably around a rotation axis 33, a cylinder block 35 that is coupled to the crankcase 34, and has a cylinder axis C inclined forward. A cylinder head 36 connected to the cylinder block 35 and a head cover 37 connected to the cylinder head 36 are provided. The cylinder head 36 is connected to an intake system 38 that introduces an air-fuel mixture into the combustion chamber and an exhaust system 39 that discharges the gas after combustion from the combustion chamber. The transmission 28 includes a continuously variable transmission (not shown) housed in a transmission case 41 that is integrated with a crankcase 34 of the engine body 32.

The link mechanism 26 includes a link member 43 connected to a bracket 42 fixed to the seat rail 15c of the side frame 15 above the crankcase 34. The link member 43 is rotatably connected to the bracket 42 about an axis parallel to the axle 29. As shown in FIG. 2, a link portion 34 a that projects upward from the upper portion of the crankcase 34 is similarly rotatably connected to the link member 43 about an axis parallel to the axle 29.

The internal combustion engine 27 includes a piston 45 incorporated in the cylinder block 35. The piston 45 has a cylinder axis C that tilts forward and is housed in a cylinder bore 46 defined in the cylinder block 35. Here, the cylinder block 35 is formed with a single cylinder bore 46 for receiving a single piston 45. A cylinder liner 47 that guides the slide of the piston 45 is fitted into the cylinder bore 46. The end 47 a of the cylinder liner 47 projects into the crank chamber inside the crankcase 34. A combustion chamber is defined between the piston 45 and the cylinder head 36.

The internal combustion engine 27 includes a crankshaft 48. The crankshaft 48 has a crank journal 51 rotatably connected to the crankcase 34 by a bearing 49, and a crank web 53 holding a crankpin 52 so as to be rotatable about its axis. An annular plate 54 formed in an annular shape around the crank journal 51 is coupled to the crankshaft 48 coaxially with the rotation axis 33. The annular plate 54 is superposed on the outer surface of the crank web 53.

On the outer periphery of the annular plate 54, a detected body 55 that projects radially outward is continuous. The detected body 55 is provided with a plurality of reluctor pieces (gear teeth) 53a arranged annularly around the rotation axis 33 of the crankshaft 48 at equal intervals. The reluctor pieces 55a are arranged, for example, at every central angle of 10 degrees. The reluctor piece 55a is made of, for example, a magnetic material. At the end 47a of the cylinder liner 47, a notch 56 that forms a relief for the detection object 55 is formed.

The internal combustion engine 27 includes a connecting rod 57. The connecting rod 57 is connected to the piston 45 at one end and is connected to the crankshaft 48 at the other end. The other end of the connecting rod 57 is rotatably connected to the crank pin 52 about the axis of the crank pin 52. The axial linear movement of the piston 45 is converted into the rotational movement of the crankshaft 48 by the action of the connecting rod 57.

The internal combustion engine 27 includes a pulsar sensor (detection sensor) 58 that faces the annular orbit of the detected body 55 and generates a pulse signal according to the movement of the detected body 55. The pulsar sensor 58 is attached to the crankcase 34 by being inserted from the outside into a sensor hole formed in the crankcase 34. The pulsar sensor 58 is held in a posture inclined with respect to the vehicle up-down direction orthogonal to the ground GD. The pulsar sensor 58 is arranged behind the link portion 34a and in front of the rear wheel WR in a side view of the vehicle.

The pulsar sensor 58 faces the crank chamber at its tip for detecting a magnetic substance. In the pulsar sensor 58, the detection axis 58a having the highest sensitivity is directed to the rotation axis 33. The pulsar sensor 58 outputs an electric signal according to the presence or absence of a magnetic substance detected on the track of the detected body 55. The pulsar sensor 58 outputs a pulse signal that specifies the angular position of the crankshaft 48. As shown in FIG. 3, the pulsar sensor 58 is arranged offset in the vehicle width direction with respect to the center plane 59 of the rear wheel WR orthogonal to the axle of the rear wheel WR. The central surface 59 constitutes a symmetrical surface that is symmetrical with respect to the rear wheel WR (particularly the tire).

As shown in FIG. 4, the crankshaft 48 includes a pair of left and right crank webs 53. The individual crank webs 53 face the corresponding bearings 49 on the outer side. A cover plate 61 formed in an annular shape around the crank journal 51 coaxially with the rotation axis 33 is continuous with the inner periphery of the annular plate 54. The cover plate 61 forms an oil sump 62 between itself and the outer surface of the crank web 53. The oil sump 62 is connected to an oil passage 63 defined in the crank pin 52 along the axis of the crank pin 52. The inner periphery of the cover plate 61 forms an annular gap around the crank journal 51, that is, a lubricating oil inlet. The inner circumference of the cover plate 61 may be in contact with the inner ring of the bearing 49. The cover plate 61 cooperates with the annular plate 54 to form a centrifugal oil filter. The centrifugal oil filter filters foreign matter in the lubricating oil based on the centrifugal force during rotation of the crank web 53.

A supply passage 64 extending from the oil passage 63 in the radial direction (direction orthogonal to the axis) is defined in the crank pin 52. The outer end of the supply path 64 opens into the bearing of the connecting rod 57. The lubricating oil in the oil sump 62 is supplied to the bearing of the connecting rod 57 via the oil passage 63 and the supply passage 64.

An oil seal 65 is arranged outside the bearing 49 between the crankshaft 48 and the crankcase 34. The crankcase 34 forms an oil chamber 66 around the crankshaft 48 between the oil seal 65 and the bearing 49. The tip of an oil passage 67 that extends from an oil pump (not shown) opens into the oil chamber 66. Lubricating oil is supplied to the oil chamber 66 by the function of an oil pump.

A groove 68 extending in the axial direction is defined on the outer peripheral surface of the crank journal 51. The groove 68 crosses at least the inner ring of the bearing 49 in the axial direction. The groove 68 forms an oil passage for connecting the oil sump 62 to an oil chamber 66 formed outside the bearing 49, between the groove 68 and the inner ring of the bearing 49. The lubricating oil supplied from the oil pump to the oil chamber 66 is introduced into the oil sump 62 through the groove 68.

Referring also to FIG. 5, the crank web 53 has an inner side surface on the back side of the outer side surface for projecting the balance weight 71 at a position offset from the pin hole 69 for receiving the crank pin 52. A fastening hole 72 is formed in the crank web 53 at a position offset from the balance weight 71. A thread groove is formed on the inner peripheral surface of the fastening hole 72. As shown in FIG. 6, in the fastening hole 72 of the crank web 53, a bolt (fastening member) 74 for fixing the annular plate 54 to the crank web 53 by passing through a circular opening 73 formed in the annular plate 54. The shaft is screwed in. The opening 73 of the annular plate 54 has a cross section with a diameter larger than the shaft diameter of the bolt 74.

As shown in FIG. 7, a knock pin (regulating member) 75 is fitted into the crank web 53 and the annular plate 54. The knock pin 75 has an axis parallel to the axis of the crankshaft 48. The pin holes 76 a and 76 b of the knock pin 75 are defined by the crank web 53 and the annular plate 54, respectively, on the mating surfaces that contact each other. The knock pin 75 restricts the displacement of the annular plate 54 along the surface of the crank web 53. As shown in FIG. 5, one or two knock pins 75 (pin holes 76a) may be arranged for each fastening hole 72.

An oil jet 77 is arranged in the crankcase 34 radially outside the crank web 53. The oil jet 77 injects lubricating oil toward the piston 45 in the cylinder 46. Lubricating oil can be supplied to the oil jet 77 from, for example, an oil pump (not shown) that is interlocked with the rotation of the crankshaft 48.

Next, the operation of the internal combustion engine 27 according to this embodiment will be described. When the internal combustion engine 27 operates and the crankshaft 48 rotates, the oil pump serves to introduce the lubricating oil into the oil chamber 66. The lubricating oil flows along the outer circumference of the crank journal 51 and flows into the oil sump 62. The lubricating oil in the oil sump 62 is retained in the oil sump 62 by the centrifugal force of the crankshaft 48. The lubricating oil flows from the oil sump 62 into the oil passage 63 in the crank pin 52. Lubricating oil is supplied from the oil passage 63 to the contact area between the crankpin 52 and the connecting rod 57 via the supply passage 64. In this way, lubrication is realized in the contact area between the crank pin 52 and the connecting rod 57.

The detected body 55 rotates integrally with the crankshaft 48. The reluctor piece 55a of the detection object 55 moves around the rotation axis 33 along an annular orbit coaxial with the rotation axis 33. The pulsar sensor 58 alternately faces the reluctor piece 55a and the space, detects the magnetic material of the reluctor piece 55a, and generates a pulse signal. Since the reluctor pieces 55a are arranged at equal intervals, the time interval of the pulse varies depending on the angular velocity. Since the detected body 55 is joined to the outer periphery of the annular plate 54 which is overlapped with the outer surface of the crank web 53 in forming the oil sump 62, a new member may be added between the crank web 53 and the bearing 49. Instead, the internal combustion engine 27 is prevented from increasing in size in the axial direction of the crankshaft 48. Moreover, since the existing parts are used, the angular velocity of the crankshaft 48 can be detected without increasing the number of parts.

In the internal combustion engine 27 according to the present embodiment, the notch 56 is formed in the cylinder liner 47. The chip 56 constitutes an escape of the detected body 55. Since the contact between the cylinder liner 47 and the detected body 55 is avoided in this way, the crankshaft 48 can be brought closer to the combustion chamber defined between the cylinder head 36 and the piston 45, and the internal combustion engine 27 Upsizing can be suppressed.

In the internal combustion engine 27, the bolt 74 serves to fix the annular plate 54 and the cover plate 61 (=centrifugal oil filter) to the crank web 53. An opening 73 is formed in the annular plate 54 for fixing. The knock pin 75 restricts the displacement of the annular plate 54 along the surface of the crank web 53. As a result, the deviation between the crank web 53 and the detected body 55 is avoided. The angular velocity of the crankshaft 48 is accurately detected.

In the crank web 53, the fastening hole 72 is arranged at a position offset from the balance weight 71. When the annular plate 54 is attached to the crank web 53, the fastening hole 72 is provided at a position offset from the balance weight 71 of the crank web 53, so that the shape of the balance weight 71 of the crank web 53 is not complicated and the crank web 53 is not formed. The detected body 55 can be coupled to 53.

The reluctor piece 55a of the detected body 55 projects from the main body of the detected body 55 in the centrifugal direction. The pulsar sensor 58 is directed to the rotation axis 33 of the crankshaft 48. In this way, the detection axis 58a is directed to the rotation axis 33 of the crankshaft 48, so that passage of the reluctor piece 55a can be accurately detected. Moreover, since the pulsar sensor 58 is attached to the crankcase 34 while being inclined with respect to the vehicle vertical direction orthogonal to the ground GD when mounted on the scooter 11, the protrusion of the pulsar sensor 58 in the height direction is suppressed. The pulsar sensor 58 can be arranged without interfering with vehicle parts.

A link portion 34a connected to the vehicle body frame 12 in front of the rear wheel WR of the scooter 11 projects upward in the crankcase 34, and a pulsar sensor 58 is arranged behind the link portion 34a and in front of the rear wheel WR. To be done. Since the pulsar sensor 49 is arranged between the link portion 34a of the internal combustion engine 27 and the rear wheel WR, the front and rear can be protected by vehicle parts without providing a protective cover on the pulsar sensor 58.

The pulsar sensor 58 is arranged offset in the vehicle width direction with respect to the center plane 59 of the rear wheel WR orthogonal to the axle 29 of the rear wheel WR. It is possible to make it difficult for water droplets splashed up along the center of the rear wheel WR in the vehicle width direction to splash on the pulsar sensor 58.

In the present embodiment, as shown in FIG. 4, not only the annular plate 54 and the detected body 55 are provided on the left crank web 53 on the opposite side of the cam chain 78, but as shown in FIG. The annular plate 54 and the detected body 55 may be provided on the crank web 53 on the right side of the chain 78 side.

Claims (7)

A crank journal (51) rotatably about an axis and connected to a crankcase (34) by a bearing (49);
A crank web (53) coupled to the crank journal (51) for holding a crank pin (52) and having an outer surface facing the bearing (49);
An annular plate (54) formed in an annular shape around the crank journal (51) and arranged on an outer surface of the crank web (53);
It is formed in an annular shape around the crank journal (51) continuously from the inner circumference of the annular plate (54) and is partitioned in the crank pin (52) between the outer surface of the crank web (53). A cover plate (61) forming an oil sump (62) connected to an oil passage (63)
A groove (68) which is defined on the outer peripheral surface of the crank journal (51) and which forms an oil passage connecting the oil sump (62) to an oil chamber (66) formed outside the bearing (49); ,
A detected body (55) continuously protruding from the outer circumference of the annular plate (54) and protruding radially outward from the outer circumference of the crank web (53);
An internal combustion engine, comprising: a detection sensor (58) facing a trajectory of the detected body (55) and generating a pulse signal according to the movement of the detected body (55). The internal combustion engine according to claim 1,
A cylinder block (35) coupled to the crankcase (34),
A cylinder liner (47) fitted to the cylinder bore (46) of the cylinder block (35) to guide the slide of the piston (45),
An internal combustion engine, characterized in that the cylinder liner (47) is provided with a notch (56) forming an escape of the object (55) to be detected. The internal combustion engine according to claim 1 or 2,
A fastening member (74) screwed to the crank web (53) and passed through an opening (73) formed in the annular plate (54) to fix the annular plate (54) to the crank web (53). )When,
And a regulation member (75) fitted into the crank web (53) and the annular plate (54) to regulate the displacement of the annular plate (54) along the surface of the crank web (53). Characterized internal combustion engine. The internal combustion engine according to claim 3,
The crank web (53) has an inner side surface on the back side of the outer side surface for projecting a balance weight (71) at a position offset from a pin hole (69) for receiving the crank pin (52). The internal combustion engine characterized in that a fastening hole (72) for receiving the fastening member (74) is formed in the (53) at a position offset from the balance weight (71). The internal combustion engine according to any one of claims 1 to 4,
The detected body (55) includes a plurality of reluctor pieces (55a) arranged in a ring around the rotation axis (33) of the crank journal (51) and read by the detection sensor (58).
The detection sensor (58) is oriented toward the rotation axis (33) of the crank journal (51) and is inclined with respect to the vehicle vertical direction orthogonal to the ground (GD) when mounted on a vehicle, so that the crank. Internal combustion engine characterized by being attached to a case (34). The internal combustion engine according to claim 5,
A link portion (34a) connected to the vehicle body frame (12) in front of the rear wheel (WR) of the vehicle is projected upward in the crankcase (34), and the detection sensor (58) is connected to the link portion. An internal combustion engine arranged behind the (34a) and in front of the rear wheel (WR). The internal combustion engine according to claim 6,
The internal combustion engine, wherein the detection sensor (58) is arranged offset in the vehicle width direction with respect to the center line of the rear wheel (WR) orthogonal to the axle of the rear wheel (WR).

Images