JP6640263B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to a crankcase defining a crankcase, a crankshaft rotatably supported by the crankcase via a pair of bearings and having a crank housed in the crankcase, and a crankshaft housed in the crankcase. The present invention relates to an internal combustion engine including a detection target supported by a shaft, and a detection sensor facing a trajectory of the detection target and detecting a movement of the detection target to generate a pulse signal.

  Patent Document 1 discloses a control device for an internal combustion engine. The internal combustion engine is configured as a single cylinder. The control unit detects misfire due to the over-lean air-fuel ratio in the single-cylinder internal combustion engine. The control device determines whether the amount of change in the angular velocity of the crankshaft between the preceding and following combustion cycles exceeds a predetermined threshold. When the number of times that the amount of change exceeds the threshold reaches a specified number of times during a preset number of cycles, the control device estimates misfire of the internal combustion engine.

  As disclosed in Patent Document 2, an electromagnetic pickup is widely used for detecting an angular velocity of a crankshaft. The crankshaft of the internal combustion engine includes an annular body continuous around the rotation axis of the crankshaft, and a plurality of reluctors (gear teeth) extending radially from the annular body and arranged at equal intervals in a circumferential direction around the rotation axis. Is fixed. The tip of the electromagnetic pickup faces the orbit of the reactor.

JP 2014-199040 A JP-A-2002-371906

  However, when the pulsar ring is attached to the crank web, the pulse signal is easily influenced by the magnetic material of the crank web because the magnetic crank web and the pulsar ring are close to each other. As a result, there has been a demand for a technique for improving the detection accuracy of the ring gear.

  The present invention has been made in view of the above situation, and has as its object to provide an internal combustion engine that can generate a pulse signal with high accuracy while avoiding the influence of magnetism of a crank web.

  According to the first aspect of the present invention, a crank web having an outer peripheral surface partitioned by a cylindrical surface coaxial with a rotation axis, an annular body superimposed on the crank web from an axial direction, and extending radially from the annular body. A plurality of reactors projecting beyond the outer peripheral surface of the crank web and arranged at equal intervals in the circumferential direction around the axis of rotation except for a region where there is no reductor; There is provided an internal combustion engine provided with a relief portion which is depressed radially inward along a mating surface of the crank web and the annular body corresponding to the region.

  According to the second aspect, in addition to the configuration of the first aspect, the outer peripheral surface of the crank web continuously forms a cylindrical surface having a larger diameter than the annular body in the circumferential direction.

  According to the third aspect, in addition to the configuration of the second aspect, the relief portion is formed by a concave portion extending over the entire area between the reactors adjacent to each other across the reactor lacking area.

  According to the fourth aspect, in addition to the configuration of the third aspect, the recess is partitioned along the outer periphery of the annular body.

  According to the fifth aspect, in addition to the configuration of the third or fourth aspect, the length of the teeth of the reactor is smaller than the depth of the concave portion specified in the thickness direction of the crank web.

  According to the sixth aspect, in addition to the configuration of any one of the third to fifth aspects, the amount of protrusion from the outer circumferential surface of the crank web to the tip of the reactor is smaller than the depth of the recess.

  According to the seventh aspect, in addition to the configuration of any one of the third to sixth aspects, the internal combustion engine further includes a second crank web connected to the crank web by a crank pin and housed in a crank chamber; A centrifugal oil filter installed on the second crank web.

  According to the eighth aspect, in addition to the configuration of any one of the third to sixth aspects, the internal combustion engine further includes a second crank web connected to the crank web by a crank pin and housed in a crank chamber; An oil jet that is disposed radially outside the second crank web and injects lubricating oil into the cylinder.

  According to the first aspect, since the reluctor does not exist in the reluctor lacking area and the periodic change such as the unevenness of the reluctor is absent, the pulse signal based on the magnetic material is compared with the area where the reluctor is arranged at equal intervals. The influence of the outer peripheral surface of the crank web is easy to ride. At this time, since the outer peripheral surface of the crank web is away from the pulser sensor in the escape portion, the influence of the magnet web magnetism can be avoided. Thus, a pulse signal can be generated with high accuracy.

  According to the second aspect, since the diameter of the annular body is reduced, the annular body can be reduced in weight and can be applied to a crank web incorporated in a limited space. In addition, since the retractor projects radially from the disc-shaped crank web, a pulse signal can be generated with high accuracy based on the retractor, and there is no need to form a relief portion over the entire circumference of the crank web. An increase in the axial dimension (thickness) of the crank web can be avoided.

  According to the third aspect, the relief portion can be formed with a simple structure.

  According to the fourth aspect, the radial depth of the recess is defined along the outer periphery of the annular body, so that the depth of the recess can be kept to a minimum. Changes in the weight balance of the crank web can be minimized.

  According to the fifth aspect, since the length of the teeth of the reactor is suppressed to be short, it is possible to prevent the reactor from being enlarged in the radial direction.

  According to the sixth aspect, the amount of protrusion of the reactor can be minimized. Therefore, an increase in the size of the internal combustion engine can be avoided.

  According to the seventh aspect, since the concave portion is provided on the crank web different from the crank web that receives the centrifugal oil filter, the arrangement of the concave portion can suppress the complication of the structure of the crank web.

  According to the eighth aspect, since the concave portion is provided on a crank web different from the crank web arranged at a position close to the oil jet, the layout of the concave portion can be suppressed from becoming complicated.

FIG. 1 is a side view schematically showing the entire configuration of a motorcycle. FIG. 1 is an enlarged partial cross-sectional view of a motorcycle schematically illustrating a structure of an internal combustion engine. FIG. 2 is an enlarged partial sectional view of the internal combustion engine schematically showing a structure of a crankshaft. FIG. 3 is an enlarged perspective view of a pulsar ring and a first crank web. FIG. 2 is an enlarged cross-sectional view of a pulsar ring and a first crank web observed on a cut surface including a rotation axis of a crankshaft. FIG. 3 is an enlarged partial cross-sectional view of a motorcycle corresponding to FIG. 2 and schematically illustrating a pulsar sensor according to another layout. FIG. 13 is an enlarged partial cross-sectional view of the motorcycle, corresponding to FIG. 2 and schematically illustrating a pulsar sensor according to still another layout. FIG. 2 is an enlarged partial cross-sectional view schematically illustrating a configuration of a multi-stage transmission. FIG. 9 is a partially enlarged sectional view of FIG. 8. FIG. 3 is an enlarged partial cross-sectional view schematically illustrating a configuration of a shift mechanism. FIG. 3 is an enlarged partial cross-sectional view of the motorcycle, corresponding to FIG. 2 and schematically illustrating a positional relationship between a pulsar ring and a multi-stage transmission. FIG. 4 is an enlarged partial cross-sectional view of the internal combustion engine corresponding to FIG. 3 and schematically showing a locking mechanism according to another specific example. FIG. 5 is an enlarged perspective view of a pulsar ring and a first crank web schematically corresponding to FIG. 4 and showing a locking mechanism according to another specific example. FIG. 9 is an enlarged plan view of a pulsar ring and a first crank web incorporated in an internal combustion engine according to another embodiment. FIG. 5 is an enlarged perspective view of the pulsar ring and the first crank web corresponding to FIG. 4.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Here, it is assumed that the up, down, front, rear, left and right of the vehicle body are defined based on the eyes of the occupant riding the motorcycle.

  FIG. 1 schematically shows the entire configuration of a motorcycle according to one embodiment of the present invention. The motorcycle 11 includes a body frame 12. A front fork 14 is steerably supported on the head pipe 13 at the front end of the body frame 12. The front fork 14 supports a front wheel WF rotatably around an axle 15. A handlebar 16 is connected to the front fork 14 above the head pipe 13. A swing arm 18 is supported by a pivot frame 17 at the rear side of the body frame 12 so as to be swingable about a support shaft 19 extending horizontally in the vehicle width direction. At the rear end of the swing arm 18, a rear wheel WR is rotatably supported around an axle 21.

  An internal combustion engine 23 is mounted on the body frame 12 between the front wheel WF and the rear wheel WR. The internal combustion engine 23 includes a crankcase 24, a cylinder block 25 connected to the crankcase 24 and extending upward from the crankcase 24, a cylinder head 26 connected to the cylinder block 25, and a head cover 27 connected to the cylinder head 26. And The crankcase 24 supports a crankshaft (described later) rotatably around a rotation axis Rx extending parallel to the axle 21 of the rear wheel WR. The rotational movement of the crankshaft is transmitted to the rear wheel WR via a power transmission device (not shown). Two engine hangers 29 are formed in the crankcase 24 at the front and two at the rear. The engine hangers 29 are vertically arranged at the front and the rear, respectively. The crankcase 24 is connected to and fixed to the body frame 12 by an engine hanger 29.

  A fuel tank 31 is mounted on the body frame 12 above the internal combustion engine 23. An occupant seat 32 is mounted on the body frame 12 behind the fuel tank 31. Fuel is supplied from the fuel tank 31 to the fuel injection device of the internal combustion engine 23. The occupant straddles the occupant seat 32 when driving the motorcycle 11.

  As shown in FIG. 2, the internal combustion engine 23 includes a piston 33 incorporated in the cylinder block 25. The piston 33 is housed in a cylinder 34 having a forwardly inclined cylinder axis and partitioned in the cylinder block 25. Here, a single cylinder 34 that receives a single piston 33 is formed in the cylinder block 25. A combustion chamber 35 is defined between the piston 33 and the cylinder head 26. The cylinder head 26 supports an intake valve, an exhaust valve, and a valve mechanism. The head cover 27 covers the valve mechanism.

  The small end of the connecting rod 36 is connected to the piston 33. A large end of the connecting rod 36 is connected to a crankshaft 37 in the crankcase 24. The linear motion of the piston 33 in the axial direction is converted into a rotational motion of the crankshaft 37 by the action of the connecting rod 36.

  The internal combustion engine 23 is coupled to the crankshaft 37 coaxially with the rotation axis Rx, and includes a pulsar ring 38 having a plurality of reluctors 38a arranged in a line at equal intervals around the rotation axis Rx. A pulser sensor 39 that generates a pulse signal in accordance with the movement of the pulser ring 38 facing the orbit. The pulsar ring 38 is formed from carbon steel or another steel material (magnetic material). The reluctors 38a are arranged, for example, at a central angle of 10 degrees, except for a reluctant area, as described later. The details of the pulsar ring 38 will be described later. The pulsar sensor 39 is configured by a rotation sensor using a magnetoresistive element such as GMR, for example.

  The pulsar sensor 39 is inserted from the outside into a sensor hole 41 formed in the crankcase 24 and attached to the crankcase 24. The pulsar sensor 39 is held in a posture inclined with respect to the vehicle vertical direction orthogonal to the ground. Here, the pulsar sensor 39 is disposed behind the cylinder block 25 and above the crankcase 24.

  The pulsar sensor 39 faces the crank chamber 24a at a tip for detecting a magnetic material. In the pulsar sensor 39, the detection axis 39a having the highest sensitivity is directed to the rotation axis Rx. The pulsar sensor 39 outputs an electric signal according to the presence or absence of a magnetic substance detected on the trajectory of the reactor 38a. The pulser sensor 39 outputs a pulse signal that specifies the angular position of the crankshaft 37.

  As shown in FIG. 3, the crankshaft 37 has a first shaft 45a that defines a journal 44a rotatably connected to a first half 43a of the crankcase 24 by a first bearing 42a. A first crank web 46 having a disc shape coaxial with 45a and a second shaft 45b defining a journal 44b rotatably connected to a second half 43b of the crankcase 24 by a second bearing 42b. The disc-shaped second crank web 47 coaxial with the two shafts 45b and the first crank web 46 and the second crank web 47 are coaxially arranged with the first shaft 45a and the second shaft 45b coaxially on the rotation axis Rx. And a crank pin 48 extending parallel to the rotation axis Rx at a position eccentric from the rotation axis Rx. The large end of the connecting rod 36 is connected to the crank pin 48 so as to be rotatable around a rotation axis parallel to the axis of the first shaft 45a and the second shaft 45b. The first half 43a and the second half 43b cooperate to define a crank chamber 24a for accommodating the first crank web 46 and the second crank web 47.

  The first bearing 42a and the second bearing 42b are each configured by a ball bearing. Therefore, the individual bearings 42a, 42b are connected to the annular outer ring member 51a fixed to the crankcase 24 and the first shaft 45a and the second shaft 45b of the crankshaft 37, and the corresponding outer ring member 51a An inner ring member 51b that rotates relatively and a plurality of balls 51c that are held between the outer ring member 51a and the inner ring member 51b and are in rolling contact with the outer ring member 51a and the inner ring member 51b are provided. The first shaft 45a and the second shaft 45b are fitted into the corresponding inner ring member 51b. What is necessary is just to press-fit. A first metal bush 52 for receiving the outer ring member 51a of the first bearing 42a is embedded in the first half 43a of the crankcase 24. A second metal bush 53 that receives the outer ring member 51a of the second bearing 42b is embedded in the second half 43b of the crankcase 24. The outer race member 51a may be fitted into the corresponding first bush 52 or second bush 53. The outer surface of the outer ring member 51a is covered with a first half 43a and a second half 43b, respectively. The outer surface of the inner ring member 51b is separated from the first half 43a and the second half 43b, respectively. The inner side surface of the outer ring member 51a faces the first crank web 46 and the second crank web 47 at an interval.

  In the first crank web 46, a pin hole 55 penetrating from the first surface 54a to the second surface 54b on the back side of the first surface 54a is defined. The pin hole 55 is formed in a cylindrical space having an axis parallel to the axis of the first shaft 45a. The crank pin 48 is fitted into the pin hole 55. The crank pin 48 may be pressed into the pin hole 55. The first crank web 46 is forged from a magnetic material such as carbon steel, for example, and has an outer peripheral surface 46a partitioned by a cylindrical surface coaxial with the rotation axis Rx, as shown in FIG. Here, the outer peripheral surface 46a of the first crank web 46 forms a continuous cylindrical surface continuously in the circumferential direction.

  On the first surface 54a of the first crank web 46, a flat surface 56 is formed which extends in an imaginary plane orthogonal to the axis of the first shaft 45a. The flat surface 56 extends annularly at least along the outer periphery of the first shaft 42. The pulsar ring 38 is overlaid on the flat surface 56. The pulsar ring 38 has an annular body 38b that has a smaller diameter than the outer peripheral surface 46a of the first crank web 46 and overlaps the first crank web 46 from the axial direction. The reactor 38 a of the pulsar ring 38 extends radially from the annular body 38 b and protrudes from the outer peripheral surface 46 a of the first crank web 46.

  As shown in FIG. 4, in the annular body 38 b of the pulsar ring 38, a reluctor lacking area 57 that lacks the reluctor 38 a is set at a predetermined position at an equal interval. In the reactor lacking area 57, the reactors 38a do not exist at regular intervals, and the spacing between the reactors 38a adjacent to each other with the reactor lacking area 57 interposed therebetween is set to an integral multiple of the regular interval. An outer peripheral surface 46a of the first crank web 46 has a relief portion which is depressed inward in the radial direction along the mating surface (flat surface 56) of the first crank web 46 and the annular body 38b corresponding to the reactor lacking area 57. 58 are provided. As shown in FIG. 2, the escape portion 58 is formed by a concave portion extending over the entire area in the circumferential direction between the reactors 38 a adjacent to each other with the reactor lacking area 57 interposed therebetween. The concave portion is partitioned along the outer periphery of the annular body 38b. The protrusion amount P from the outer peripheral surface 46a of the first crank web 46 to the tip of the reactor 38a is smaller than the depth D of the concave portion 58. As shown in FIG. 5, the length H of the teeth of the reactor 38a is smaller than the depth G of the concave portion specified in the thickness direction of the first crank web 46.

  In the second crank web 47, a pin hole 61 penetrating from the first surface 59a to the second surface 59b on the back side of the first surface 59a is defined. The pin hole 61 is formed in a cylindrical space having an axis parallel to the axis of the second shaft 45b. The crank pin 48 is fitted into the pin hole 61. The crank pin 48 may be pressed into the pin hole 61. The second surface 54b of the first crank web 46 and the second surface 59b of the second crank web 47 face each other.

  A centrifugal oil filter 62 is provided on the first surface 59a of the second crank web 47. The centrifugal oil filter 62 is housed in a depression on the first surface 59a. The centrifugal oil filter 62 filters foreign substances in the lubricating oil based on the centrifugal force during rotation of the second crank web 47.

  A crank weight 63a is formed integrally with the second surface 54b of the first crank web 46. The center of gravity of the first crank web 46 is located, for example, at a position shifted by 180 degrees from the axis of the pin hole 55 around the axis of the first shaft 45a. Similarly, a crank weight 63b is integrally formed on the second surface 59b of the second crank web 47. The center of gravity of the second crank web 47 is located, for example, at a position shifted by 180 degrees from the axis of the pin hole 61 around the axis of the second shaft 45b. The rotation unevenness of the rotating crankshaft 37 is suppressed to a minimum by the function of the crank weights 63a and 62.

  An oil jet 64 is arranged on the crankcase 24 on the radial outside of the centrifugal oil filter 62. The oil jet 64 injects lubricating oil in the cylinder 34 toward the piston 33. The lubricating oil can be supplied to the oil jet 64 from, for example, an oil pump (not shown) interlocked with the rotation of the crankshaft 37.

  Referring also to FIG. 4, in the center of the pulsar ring 38, a through-hole 65 that fits into the journal 44 a of the first shaft 45 a is defined, and a cylindrical protrusion 66 that projects in the axial direction of the first shaft 45 a is formed. Is done. The outline of the through hole 65 is formed in a circular shape concentric with the first shaft 45a. The pulsar ring 38 comes into surface contact with the inner ring member 51b of the first bearing 42a at the end surface 66a of the protrusion 66. Thus, the pulsar ring 38 is sandwiched between the inner race member 51b of the first bearing 42a and the flat surface 56 of the first crank web 46. Although the pulsar ring 38 is pressed against the inner ring 51b of the first bearing 42a, the space between the surface of the pulsar ring 38 and the outer ring member 51a of the first bearing 42a is ensured by the protrusion 66.

  A locking mechanism 67 is formed between the pulsar ring 38 and the first crank web 46 to prevent the relative rotation of the pulsar ring 38 and the first crank web 46 around the rotation axis Rx of the crankshaft 37. The engaging mechanism 67 is formed integrally with the pulsar ring 38, and protrudes from a surface overlapping (or facing) the first surface 54 a of the first crank web 46, and a flat surface 56 of the first crank web 46. And a recess 69 formed to receive the projecting piece 68 of the pulsar ring 38. Here, since the pulsar ring 38 is formed by pressing from a metal plate, the protruding piece 68 is cut and raised from the plate. The valley fold line of the protruding piece 68 extends in a tangential direction in contact with the concentric circle of the pulsar ring 38. Therefore, the protruding piece 68 shows a high rigidity against a load from the circumferential direction of the pulsar ring 38 even though it is a plate material.

  The depression 69 has a vertical surface 69 a that contacts the contour of the protruding piece 68. The vertical surface 69a corresponds to a plane parallel to the axis of the first shaft 45a. Preferably, the vertical surface 69a extends in an imaginary plane including the axis of the first axis 45a. If the vertical surface 69 a is orthogonal to the circumferential direction of the first crank web 46 in this way, the load in the circumferential direction of the first crank web 46 can be dispersed and transmitted to the protruding piece 68.

  Next, the operation of the internal combustion engine 23 according to the present embodiment will be described. In the internal combustion engine 23, the crankshaft 37 rotates according to the combustion. During rotation of the crankshaft 37, the pulsar ring 38 rotates integrally with the crankshaft 37. During combustion, vibration and bending occur in the crankshaft 37. Since the vibration and the bending are supported by the first bearing 42a and the second bearing 42b, the vibration and the bending of the crankshaft 37 are minimized by the journal 44a connected to the first bearing 42a. Thus, the crank angle can be detected in a state where the vibration and the bending generated from the crankshaft 37 are suppressed.

  In detecting the crank angle, the reactors 38a are arranged at equal intervals in the circumferential direction except for the reactor lacking area 57. Therefore, the outer peripheral surface 46a of the first crank web 46 has a larger diameter than the annular body 38b of the pulsar ring 38. Despite being formed by the surface, the magnetism periodically changes according to the distance from the pulsar sensor 39 between the outer peripheral surface 46a of the first crank web 46 and the reluctor 38a, so that the pulse is accurately generated by the pulsar sensor 39. A signal is generated. On the other hand, in the reluctor lacking area 57, since the reluctor 38a does not exist and there is no periodic change such as unevenness of the reluctor 38a, the pulse signal based on magnetism is smaller than the area where the reluctor 38a is arranged at equal intervals. The influence of the outer peripheral surface 46a of the first crank web 46 is easy to ride. At this time, since the outer peripheral surface 46a of the first crank web 46 moves away from the pulser sensor 39 in the escape portion 58, the influence of the magnetism of the first crank web 46 is avoided. Thus, a pulse signal is generated with high accuracy.

  In the present embodiment, the outer peripheral surface 46a of the first crank web 46 continuously forms a cylindrical surface having a larger diameter than the annular body 38b in the circumferential direction. Since the diameter of the annular body 38b is reduced, the weight of the annular body 38b is reduced, and the crank webs 46 and 47 installed in a limited space can be easily applied. Further, since the reactor 38a protrudes radially from the disc-shaped first crank web 46, a pulse signal is accurately generated based on the reluctor 38a, and the relief portion 57 is formed over the entire circumference of the first crank web 46. It is not necessary to increase the axial dimension (thickness) of the first crank web 46.

  In the present embodiment, the escape portion 58 is formed by a concave portion extending over the entire area between the reactors 38a adjacent to each other with the reactor lacking area 57 interposed therebetween. Therefore, the escape portion 57 is formed with a simple structure. The concave portion is partitioned along the outer periphery of the annular body 38b. Thus, the radial depth D of the concave portion is defined along the outer periphery of the annular body 38b, so that the concave portion depth D is kept to a minimum. Changes in the weight balance of the first crank web 46 are kept to a minimum. In addition, since the projection amount P from the outer peripheral surface 46a of the first crank web 46 to the tip of the reactor 38b is smaller than the depth D of the concave portion, the projection amount P of the reactor 38a is minimized, and the large size of the internal combustion engine is reduced. Is avoided. In addition, since the length H of the teeth of the reactor 38a is smaller than the depth G of the concave portion specified in the thickness direction of the first crank web 46, the length H of the teeth of the reactor 38a is suppressed to be short. Is suppressed from increasing in the radial direction.

  The pulsar ring 38 is disposed between the inner race member 51b of the first bearing 42a and the first crank web 46. The movement of the pulsar ring 38 in the axial direction of the crankshaft 37 is restricted by the inner ring member 51b of the first bearing 42a and the first crank web 46 of the crankshaft 37. In mounting the pulsar ring 38, there is no need for a regulating component specific to the pulsar ring 38 again. Reduction of the number of parts and simplification of the assembly work process are realized.

  A locking mechanism 67 is formed between the pulsar ring 38 and the first crank web 46 to prevent the relative rotation of the pulsar ring 38 and the crankshaft 37 around the rotation axis Rx of the crankshaft 37. The locking mechanism 67 prevents the relative rotation of the pulsar ring 38 and the crankshaft 37 during the rotation of the crankshaft 37. Therefore, the pulsar ring 38 is reliably synchronized with the rotation of the crankshaft 37. The movement of the pulsar ring 38 reliably reflects the rotation of the crankshaft 37.

  In the present embodiment, the crank of the crankshaft 37 has a first shaft 45a and a crank weight 63a rotatably supported on a first bearing 42a around a rotation axis Rx, and a first crank web supporting the pulsar ring 38. 46, a second shaft 45b rotatably supported by a second bearing 42b around a rotation axis Rx and a crank weight 63b, and a second crank web 47 supporting a centrifugal oil filter 62, and rotation of the crank shaft 37. A crank pin 48 is disposed at a position displaced from the axis Rx, connects the first crank web 46 and the second crank web 47 to each other, and is connected to the connecting rod 36. The pulsar ring 38 is attached to the first crank web 46 while the centrifugal oil filter 62 is attached to the second crank web 47, so that the pulsar ring 38 is connected to the first crank web 46 without complicating the member layout. can do. In addition, since the concave portion of the relief portion 58 is provided on the first crank web 46 different from the second crank web 47 that receives the centrifugal oil filter 62, the arrangement of the concave portion suppresses complication of the structure of the crank webs 46 and 47. Is done.

  In the internal combustion engine 23 according to the present embodiment, the oil jet 64 is disposed radially outside the second crank web 47 and injects lubricating oil into the cylinder 34. Since the concave portion of the relief portion 58 is provided on the first crank web 46 different from the second crank web 47 disposed at a position close to the oil jet 64, complication of the member layout is suppressed in arranging the concave portion.

  In the internal combustion engine 23, the pulsar sensor 39 is mounted on the upper side of the crankcase 24 behind the cylinder block 25. Since the pulsar sensor 39 is disposed behind the cylinder block 25 extending upward from the crankcase 24, it is possible to protect the front of the pulsar sensor 39 without providing a protective cover on the pulsar sensor 39.

  As described above, the pulsar sensor 39 is disposed between the engine hangers 29 formed on the crankcase 24. Since the crankcase 24 is fixed to the body frame 12 by the engine hanger 29, the front and rear of the pulsar sensor 39 can be protected without providing a protective cover on the pulsar sensor 39.

  In addition, as shown in FIG. 6, the pulsar sensor 39 may be attached to the front wall of the crankcase 24. The pulsar sensor 39 may be held in a posture inclined with respect to the vehicle vertical direction orthogonal to the ground. As described above, the detection axis 39a of the pulsar sensor 39 may be directed to the rotation axis Rx of the crankshaft 37. Since other components hardly exist in front of the crankcase 24 and an open space is secured, the influence on the layout of other components when the pulsar sensor 39 is mounted can be suppressed. As shown in FIG. 7, the pulsar sensor 39 may be attached to the front wall of the crankcase 24 between the pair of upper and lower engine hangers 29. Since the body frame 12 (down frame extending downward from the head pipe 13) is coupled to the engine hanger 29 from the front, the front and rear of the pulsar sensor 39 are protected without providing a dedicated protective cover for the pulsar sensor 39. can do.

  As shown in FIG. 8, a dog clutch type multi-stage transmission (power transmission device) 71 is incorporated in the internal combustion engine 23. The multi-stage transmission 71 includes a main shaft 72 and a counter shaft 73 having an axis parallel to the axis of the crankshaft 37 (rotation axis Rx). The main shaft 72 and the counter shaft 73 are rotatably supported by the first half 43a and the second half 43b by bearings 75 and 76 respectively fitted in the first half 43a and the second half 43b of the crankcase 24. You. The main shaft 72 is connected to the crankshaft 37 through a primary reduction mechanism 77. The primary reduction mechanism 77 includes a drive gear 77a fixed to the crankshaft 37 and a driven gear 77b supported on the main shaft 72 so as to be relatively rotatable. The driven gear 77b meshes with the driving gear 77a. A drive sprocket 78 is connected to the counter shaft 73.

  Five drive gears are arranged on the main shaft 72. The drive gears include a low drive gear 79, a fourth speed drive gear 81, a third speed drive gear 82, a fifth speed drive gear 83, and a second speed drive gear 84 in order between the bearings 75. Similarly, five driven gears are arranged on the counter shaft 73 between the bearings 76 in order. The driven gears include a low driven gear 85, a fourth speed driven gear 86, a third speed driven gear 87, a fifth speed driven gear 88, and a second speed driven gear 89. In the multi-stage transmission 71, the coupling state can be selectively switched among a neutral state, a first-speed coupling state, a second-speed coupling state, a third-speed coupling state, a fourth-speed coupling state, and a fifth-speed coupling state. Details of the multi-stage transmission 71 will be described later.

  A friction clutch 91 is incorporated in the internal combustion engine 23. The friction clutch 91 includes a clutch outer 91a and a clutch hub 91b. The driven gear 77b of the primary reduction mechanism 77 is connected to the clutch outer 91a. In the friction clutch 91, connection and disconnection are switched between the clutch outer 91a and the clutch hub 91b in accordance with the operation of the clutch lever.

  As shown in FIG. 9, in the multi-stage transmission 71, the low drive gear 79 is carved on the main shaft 72. The fourth speed drive gear 81 is supported by the main shaft 72 so as to be rotatable relative to the main shaft 72 and non-displaceable in the axial direction. The third speed drive gear 82 is integrated with the first shifter 92. The first shifter 92 is fitted to a spline 72a engraved on the main shaft 72, and is supported on the spline 72a so as to be relatively nonrotatable and axially displaceable. The fifth speed drive gear 83 is supported by the main shaft 72 so as to be rotatable relative to the main shaft 72 and not to be displaceable in the axial direction. The second speed drive gear 84 is supported by the main shaft 72 so as not to rotate relative to the main shaft 72 and to be displaceable in the axial direction.

  A first fitting mechanism 93 is configured between the fourth speed drive gear 81 and the third speed drive gear 82. The first fitting mechanism 93 includes a plurality of driving protrusions 93 a formed on the first shifter 92 and a plurality of driven protrusions 93 b formed on the fourth speed drive gear 81. When the first shifter 92 is located at the axial reference position on the spline 72a, the trajectory of the driving projection 93a is separated from the trajectory of the driven projection 93b. At this time, relative rotation between the fourth speed drive gear 81 and the first shifter 92 around the axis of the main shaft 72 is allowed. When the first shifter 92 is displaced from the axial reference position toward the fourth speed drive gear 81 by the first distance and moves to the first operating position, the drive protrusion 93 a is circumferentially adjacent to the fourth speed drive gear 81. It enters between the driven projections 93b. The driven projection 93b and the driving projection 93a mesh with each other around the axis of the main shaft 72. At the time of meshing, the fourth speed drive gear 81 is non-rotatably coupled to the main shaft 72 via the first shifter 92.

  A second fitting mechanism 94 is configured between the third speed drive gear 82 and the fifth speed drive gear 83. The second fitting mechanism 94 includes a plurality of driving protrusions 94a formed on the first shifter 92 and a plurality of driven protrusions 94b formed on the fifth speed drive gear 83. When the first shifter 92 is located at the axial reference position on the spline 72a, the trajectory of the driving projection 94a is separated from the trajectory of the driven projection 94b. At this time, relative rotation around the axis of the main shaft 72 is allowed between the first shifter 92 and the fifth speed drive gear 83. When the first shifter 92 is displaced from the axial reference position toward the fifth speed drive gear 84 by the second distance and moves to the second operating position, the drive protrusion 94a is adjacent to the fifth speed drive gear 83 in the circumferential direction. It enters between the driven projections 94b. The driving projection 94a and the driven projection 94b mesh with each other around the axis of the main shaft 72. At the time of meshing, the fifth speed drive gear 83 is non-rotatably coupled to the main shaft 72 via the first shifter 92.

  The low driven gear 85 is supported by the counter shaft 73 so as to be relatively rotatable and axially displaceable. The low driven gear 85 meshes with the low drive gear 79 on the main shaft 72. The fourth speed driven gear 86 is integrated with the second shifter 95. The second shifter 95 is fitted to a first spline 73a carved on the counter shaft 73, and is supported on the first spline 73a so as to be relatively non-rotatable and axially displaceable. The third-speed driven gear 87 is supported by the counter shaft 73 so as to be rotatable relative to the counter shaft 73 and non-displaceable in the axial direction. The fifth speed driven gear 88 is integrated with the third shifter 96. The third shifter 96 is fitted to a second spline 73b carved on the counter shaft 73, and is supported on the second spline 73b so as to be relatively non-rotatable and axially displaceable. The second-speed driven gear 89 is supported by the counter shaft 73 so as to be relatively rotatable and axially displaceable. The second speed driven gear 89 meshes with the second speed drive gear 84 on the main shaft 72.

  A third fitting mechanism 97 is configured between the low driven gear 85 and the fourth speed driven gear 86. The third fitting mechanism 97 includes a plurality of driving projections 97a formed on the second shifter 95 and a plurality of driven projections 97b formed on the low driven gear 85. When the second shifter 95 is located at the axial reference position on the first spline 73a, the trajectory of the driving projection 97a is separated from the trajectory of the driven projection 97b. At this time, relative rotation between the second shifter 95 and the low driven gear 85 around the axis of the counter shaft 73 is allowed. When the second shifter 95 is displaced by a third distance from the axial reference position toward the row driven gear 85 and moves to the third operating position, the driving projection 97a is circumferentially adjacent on the row driven gear 85. It enters between the driven projections 97b. The driving projection 97a and the driven projection 97b mesh with each other around the axis of the counter shaft 73. When engaged, the low driven gear 85 is non-rotatably coupled to the counter shaft 73 via the second shifter 95.

  A fourth fitting mechanism 98 is configured between the fourth speed driven gear 86 and the third speed driven gear 87. The fourth fitting mechanism 98 includes a plurality of driving projections 98a formed on the second shifter 95 and a plurality of driven projections 98b formed on the third-speed driven gear 87. When the second shifter 95 is located at the axial reference position on the first spline 73a, the trajectory of the driving projection 98a is separated from the trajectory of the driven projection 98b. At this time, relative rotation between the second shifter 95 and the third-speed driven gear 87 around the axis of the counter shaft 73 is allowed. When the second shifter 95 is displaced by a fourth distance from the axial reference position toward the third-speed driven gear 87 and moves to the fourth operating position, the driving projection 98a is circumferentially moved on the third-speed driven gear 87. It enters between adjacent driven projections 98b. The driving projection 98a and the driven projection 98b mesh with each other around the axis of the counter shaft 73. When engaged, the third-speed driven gear 87 is non-rotatably coupled to the counter shaft 73 via the second shifter 95.

  A fifth fitting mechanism 99 is provided between the fifth driven gear 88 and the second driven gear 89. The fifth fitting mechanism 99 includes a plurality of driving protrusions 99a formed on the third shifter 96 and a plurality of driven protrusions 99b formed on the second-speed driven gear 89. When the third shifter 96 is located at the axial reference position on the second spline 73b, the trajectory of the driving projection 99a moves away from the trajectory of the driven projection 99b. At this time, relative rotation between the third shifter 96 and the second speed driven gear 89 around the axis of the counter shaft 73 is allowed. When the third shifter 96 is displaced by a fifth distance from the axial reference position toward the second speed driven gear 89 and moves to the fifth operating position, the driving projection 99a is circumferentially moved on the second speed driven gear 89. It enters between adjacent driven projections 99b. The driving projection 99a and the driven projection 99b mesh with each other around the axis of the counter shaft 73. When engaged, the second speed driven gear 89 is non-rotatably coupled to the counter shaft 73 via the third shifter 96.

  In the present embodiment, the driving protrusions 94a, 97a, 98a, 99a and the driven protrusion 93b are protrusions extending in the axial direction of the main shaft 72 and the counter shaft 73, and the driven protrusions 94b respectively corresponding to them. 97b, 98b, 99b and the drive projection 93a are formed by an engaging hole or a peripheral wall of a depression for receiving the projection. The protrusion comes into surface contact with the peripheral wall of the engagement hole or depression in the rotation direction of the main shaft 72 or the counter shaft 73. The protrusion and the engagement hole (or the depression) may define a contact surface that spreads in an imaginary plane including the axis of the main shaft 72 or the counter shaft 73, respectively.

  On the main shaft 72, the first shifter 92, that is, the third speed drive gear 82 is located at the axial reference position, and on the counter shaft 73, the second shifter 95 and the third shifter 96 (that is, the fourth speed driven gear 86 and the fifth speed driven gear 86). When the drive gear 88) is located at the axial reference position, the fourth speed drive gear 81 on the main shaft 72 meshes with the fourth speed driven gear 86 on the counter shaft 73, and the third speed drive gear 82 on the main shaft 72 is The fifth-speed driven gear 87 on the main shaft 72 meshes with the third-speed driven gear 87 on the shaft 73. The fourth speed drive gear 81 and the fifth speed drive gear 83 rotate relative to the main shaft 72. The low driven gear 85, the third-speed driven gear 87 and the second-speed driven gear 89 rotate relative to the counter shaft 73. In this state, no rotational force is transmitted from the main shaft 72 to the counter shaft 73. In the multi-stage transmission 71, a neutral state is established.

  When the second shifter 95, that is, the fourth speed driven gear 86 moves from the neutral position to the third operating position on the counter shaft 73 from the axial reference position, the driving projection 97a of the second shifter 95 is moved by the third fitting mechanism 97. It engages with the driven projection 97b of the low driven gear 85. The low driven gear 85 is connected to the counter shaft 73. The rotational force of the main shaft 72 transmitted to the low driven gear 85 drives the counter shaft 73. Thus, in the multi-stage transmission 71, the first speed is established.

  When the third shifter 96, that is, the fifth speed driven gear 88 moves from the axial reference position to the fifth operating position on the counter shaft 73 from the neutral state, the driving projection 99a of the third shifter 96 is moved by the fifth fitting mechanism 99. The driven projection 99b of the second-speed driven gear 89 meshes with the driven projection 99b. The second speed driven gear 89 is connected to the counter shaft 73. The rotational force of the main shaft 72 transmitted to the second speed driven gear 89 drives the counter shaft 73. Thus, the second speed is established in the multi-stage transmission 71.

  When the second shifter 95, that is, the fourth speed driven gear 86 moves from the axial reference position to the fourth operating position on the counter shaft 73 from the neutral state, the driving projection 98a of the second shifter 95 is moved by the fourth fitting mechanism 98. The driven projection 98b of the third-speed driven gear 87 meshes with the driven projection 98b. The third speed driven gear 87 is connected to the counter shaft 73. The rotational force of the main shaft 72 transmitted to the third speed driven gear 87 drives the counter shaft 73. Thus, in the multi-stage transmission 71, the third speed is established.

  When the first shifter 92, that is, the third speed drive gear 82 moves from the axial reference position to the first operating position on the main shaft 72 from the neutral state, the first fitting mechanism 93 causes the drive projection 93a of the first shifter 92 to move to the fourth position. It meshes with the driven projection 93b of the high-speed drive gear 81. Fourth speed drive gear 81 is coupled to main shaft 72. The torque of the main shaft 72 is transmitted to the fourth speed drive gear 81. Since the fourth speed drive gear 81 of the main shaft 72 meshes with the fourth speed driven gear 86 of the counter shaft 73, the rotational force of the main shaft 72 drives the counter shaft 73. Thus, the fourth speed is established in the multi-stage transmission 71.

  When the first shifter 92, that is, the third-speed drive gear 82 moves from the axial reference position to the second operating position on the main shaft 72 from the neutral state, the driving projection 94a of the first shifter 92 becomes 5 by the second fitting mechanism 94. It meshes with the driven projection 94b of the high speed drive gear 83. The fifth speed drive gear 83 is connected to the main shaft 72. The rotational force of the main shaft 72 is transmitted to the fifth speed drive gear 83. Since the fifth speed drive gear 83 of the main shaft 72 meshes with the fifth speed driven gear 88 of the counter shaft 73, the rotational force of the main shaft 72 drives the counter shaft 73. Thus, in the multi-stage transmission 71, the fifth speed is established.

  As shown in FIG. 10, the shift mechanism 101 is incorporated in the multi-stage transmission 71. The shift mechanism 101 includes a guide shaft 102 extending parallel to the axis of the main shaft 72. A shift fork 103 is supported on the guide shaft 102 so as to be displaceable in the axial direction. The shift fork 103 extends in a direction perpendicular to the axis of the guide shaft 102 and is connected to the first shifter 92 on the main shaft 72.

  The shift mechanism 101 includes a shift drum 104. The shift drum 104 is rotatably supported around a rotation axis Rx extending parallel to the axis of the guide shaft 102. A cam groove 105 is formed on the outer peripheral surface of the shift drum 104. The cam groove 105 is displaced in the axial direction of the shift drum 104 according to the rotation angle. A pin 106 protruding from the shift fork 103 in a direction perpendicular to the axis of the guide shaft 102 is inserted into the cam groove 105. Thus, the shift fork 103 moves along the guide shaft 102 according to the rotation of the shift drum 104. Movement of the shift fork 103 causes movement of the first shifter 92 on the main shaft 72.

  As shown in FIG. 11, a similar shift mechanism is associated with the second shifter 95 and the third shifter 96 on the counter shaft 73. The shift mechanism 101 is supported by the guide shaft 107 extending parallel to the axis of the counter shaft 73 and the guide shaft 107 so as to be displaceable in the axial direction, and is provided on the second shifter 95 and the third shifter 96 on the counter shaft 73, respectively. And two shift forks 108 and 109 that are individually connected. The two shift forks 108 and 109 each have a pin inserted into the cam groove 105 of the shift drum 104, and move along the guide shaft 107 according to the rotation of the shift drum 104.

  In the present embodiment, the pulsar ring 38 includes the fourth-speed drive gear 81 and the fifth-speed drive gear 51 on the main shaft 72 of the multi-stage transmission 71 in a side view observed from a viewpoint located at infinity of the rotation axis Rx of the crankshaft 37. It interferes with the drive gear 83. In other words, the fifth-speed drive gear 83 and the fourth-speed drive gear 81 enter the inside of a virtual cylindrical surface 111 having a central axis on the rotation axis Rx of the crankshaft 37 and partitioning the outermost edge of the pulsar ring 38. In addition, the interference area between the pulsar ring 38 and the drive gears 81 and 83, and the pulsar sensor 39 include a virtual plane 112 including the rotation axis Rx of the crankshaft 37 and the rotation axis of the counter shaft 73, and a rotation axis of the crankshaft 37. It is disposed in a space partitioned behind the cylinder block 25 by a virtual plane 113 parallel to Rx and including the cylinder axis C. Therefore, in a perspective view in a side view, the pulsar ring 38 and the drive gears 81 and 83 are located in a region partitioned by the straight line including the center of the crankshaft 37 and the center of the countershaft 73 and the cylinder axis C behind the cylinder block 25. And the pulsar sensor 39 are located.

  The interference area between the pulsar ring 38 and the drive gears 81 and 83 is arranged in one space divided by a virtual plane 112 including the rotation axis Rx of the crankshaft 37 and the axis of the counter shaft 73, and is divided by the virtual plane 112. The shift drum 104 of the multi-stage transmission 71 is disposed in the other space. In other words, in the side view perspective view, the interference area between the pulsar ring 38 and the drive gears 81 and 83 is located above a straight line connecting the center of the crankshaft 37 and the center of the counter shaft 73, and the shift drum 104 It is located below a straight line connecting the center of the crankshaft 37 and the center of the counter shaft 73. The pulsar sensor 39 is arranged in one space divided by a virtual plane 114 including the rotation axis Rx of the crankshaft 37 and the axis of the main shaft 72, and shifts the multi-stage transmission 71 to the other space divided by the virtual plane. The drum 104 is arranged. In other words, in a perspective view in a side view, the pulsar sensor 39 is positioned above a straight line connecting the center of the crankshaft 37 and the center of the main shaft 72, and the shift drum 104 is connected to the center of the crankshaft 37 and the main shaft 72. It is located below the straight line connecting the centers. Further, the interference area between the pulsar ring 38 and the driving gears 81 and 83 and the pulsar sensor 39 are parallel to the direction of gravity and behind the virtual vertical plane 115 including the rotation axis Rx of the crankshaft 37, and It is arranged in front of a virtual vertical plane 116 that is parallel to the direction and that includes the axis of the shift drum 104. In other words, in the side view perspective view, the interference area between the pulsar ring 38 and the drive gears 81 and 83 and the pulsar sensor 39 are behind a straight line that passes through the rotation axis Rx of the crankshaft 37 in the direction of gravity. , And is located in front of a straight line passing through the axis of the shift drum 104 in the direction of gravity.

  The main shaft 72 of the transmission 71 includes a virtual plane 112 including the rotation axis Rx of the crankshaft 37 and the axis of the counter shaft 73, and a virtual plane 117 including the rotation axis Rx of the crankshaft 37 and the detection axis 39 a of the pulsar sensor 39. It is arranged in the space sandwiched by. That is, in a perspective view in a side view, the main shaft 72 is located in a region sandwiched between a straight line connecting the center of the crankshaft 37 and the center of the counter shaft 73 and the detection axis 39a of the pulsar sensor 39. Similarly, the interference area between the pulsar ring 38 and the drive gears 81 and 83 is located in a region between the straight line connecting the center of the crankshaft 37 and the center of the counter shaft 73 and the axis of the pulsar sensor 39.

  In assembling the internal combustion engine 23, the crankshaft 37, the main shaft 72 of the transmission 71, and the counter shaft 73 are assembled to the second half 43b of the crankcase 24. At this time, if the crankshaft 37 is press-fitted into the bearing 42b prior to the main shaft 72, the pulsar ring 38 is not attached to the crankshaft 37. The fourth drive gear 81 and the third drive gear (first shifter 92) are attached to the main shaft 72, while the fifth drive gear 83 and the second drive gear 84 are not attached. All driven gears 85 to 89 are mounted on the counter shaft 73. Subsequently, the pulsar ring 38 is fixed to the crankshaft 37. Thereafter, the fifth speed drive gear 83 and the second speed drive gear 84 are mounted on the main shaft 72.

  When the main shaft 72 is fitted into the bearing 75 prior to the crankshaft 37, the fourth drive gear 81 and the third drive gear (first shifter 92) are mounted on the main shaft, while the fifth drive gear is mounted. 83 and the second drive gear 84 are not attached. In the subsequent assembling of the crankshaft 37, the pulsar ring 38 may be fixed to the crankshaft 37 in advance. After assembling the crankshaft 37, the fifth speed drive gear 83 and the second speed drive gear 84 are mounted on the main shaft 72.

  In the internal combustion engine 23, as shown in FIGS. 12 and 13, a knock pin 121 protruding from the first crank web 46, as shown in FIGS. An engaging mechanism 123 formed in the pulsar ring 38 and having a through hole 122 for receiving the knock pin 121 when the pulsar ring 38 is overlaid on the first crank web 46 may be used. The knock pin 121 is formed on the first crank web 46 and has a large-diameter portion 121a that is press-fitted into a fitting hole 124 of a cylindrical space having a central axis parallel to the rotation axis Rx of the crankshaft 37, and a surface of the first crank web 46. And a small-diameter portion 124b that protrudes from the sensor ring 38 and that is pressed into the through hole 122 of the sensor ring 38. The knock pin 121 prevents relative rotation of the pulsar ring 38 and the first crank web 46 around the rotation axis Rx of the crankshaft 37.

  As shown in FIGS. 14 and 15, the internal combustion engine 23 has a disk-shaped first crank web 46 coaxial with the first shaft 45a and a disk-shaped second crank coaxial with the second shaft 45b. A first crank web 131 having a first shaft 45a in place of the web 47 and supporting the crankpin 48 in a narrow area cut off from a cylindrical surface coaxial with the rotation axis Rx toward the rotation axis Rx; and , The second crank web 132 having the second shaft 45b and supporting the crankpin 48 in a narrow region cut off from the cylindrical surface coaxial with the rotation axis Rx toward the rotation axis Rx may be used. The first crank web 131 includes, for example, a crank weight 133 having an outer peripheral surface 133a partitioned by a cylindrical surface coaxial with the rotation axis Rx at a position shifted by 180 degrees from the crank pin 48 around the rotation axis Rx. The outer peripheral surface 133a of the crank weight 133 is formed to have a larger diameter than the annular body 38b, and the reactor 38a of the pulsar ring 38 extends radially from the annular body 38b and protrudes from the outer peripheral surface 133a of the crank weight 133. Similarly, the second crank web 132 may include a crank weight 134 having an outer peripheral surface 134a partitioned by a cylindrical surface coaxial with the rotation axis Rx at a position deviated by 180 degrees from the crank pin 48 around the rotation axis Rx. .

  In the crank weight 133 of the first crank web 131, a relief portion 58 which is depressed radially inward along the mating surface of the first crank web 131 and the annular body 38b is provided corresponding to the reluctant region 57. The escape portion 58 is formed by a concave portion extending over the entire area in the circumferential direction between the reactors 38 a adjacent to each other with the reactor lacking area 57 interposed therebetween. The concave portion is partitioned along the outer periphery of the annular body 38b. The projection amount P from the outer peripheral surface 133a of the crank weight 133 to the tip of the reactor 38a is smaller than the depth D of the recess 58. In addition, the configuration of the first crank web 131 may be the same as that of the first crank web 46 described above.

23: Internal combustion engine, 24a: Crank chamber, 34: Cylinder, 38a: Reactor, 38b: Annular body, 46: Crank web (first crank web), 46a: Outer peripheral surface, 47: Second crank web (Second crank) Web), 48 ... Crank pin, 57 ... Reactor lacking area, 58 ... Escape part, 62 ... Centrifugal oil filter, 64 ... Oil jet, 131 ... First crank web, 133a ... Outer peripheral surface, D ... (recess) depth , P ... The amount of protrusion (of the reactor), Rx ... The axis of rotation (of the crankshaft).

Claims (8)

A crank web (46; 131) having an outer peripheral surface (46a; 133a) partitioned by a cylindrical surface coaxial with the rotation axis (Rx);
An annular body (38b) superimposed on the crank web (46; 131) from an axial direction;
It extends radially from the annular body (38b), protrudes from the outer peripheral surface (46a; 133a) of the crank web (46; 131), and except for a region lacking a reluctor (57) in the circumferential direction around the rotation axis (Rx). An internal combustion engine (23) including a plurality of reactors (38a) arranged at equal intervals,
The outer peripheral surface (46a; 133a) of the crank web (46; 131) is provided on the mating surface of the crank web (46; 131) and the annular body (38b) in correspondence with the reluctor lacking area (57). An internal combustion engine characterized in that a relief portion (58) is provided which is depressed radially inward along the same.   The internal combustion engine according to claim 1, wherein an outer peripheral surface (46a) of the crank web (46) continuously forms a cylindrical surface having a larger diameter than the annular body (38b) in a circumferential direction. Internal combustion engine.   3. The internal combustion engine according to claim 2, wherein the relief portion (58) is formed as a concave portion extending over the entire area between the reactors (38 a) adjacent to each other with the reactor lacking area (57) interposed therebetween. Internal combustion engine.   The internal combustion engine according to claim 3, wherein the recess is partitioned along an outer periphery of the annular body (38b).   The internal combustion engine according to claim 3 or 4, wherein the length of the teeth of the reactor (38a) is smaller than the depth of the concave portion specified in the thickness direction of the crank web (46). organ.   The internal combustion engine according to any one of claims 3 to 5, wherein a projection amount (P) from an outer peripheral surface (46a) of the crank web (46) to a tip of the reluctor (38a) is a depth of the concave portion. An internal combustion engine characterized by being smaller than (D).   The internal combustion engine according to any one of claims 3 to 6, wherein a second crank web (47) connected to the crank web (46) by a crank pin (48) and housed in a crank chamber (24a). An internal combustion engine further comprising: a centrifugal oil filter (62) installed on the second crank web (47).   The internal combustion engine according to any one of claims 3 to 6, wherein a second crank web (47) connected to the crank web (46) by a crank pin (48) and housed in a crank chamber (24a). And an oil jet (64) disposed radially outside the second crank web (47) to inject lubricating oil into the cylinder (34).

Images