CN214741701U

CN214741701U - Internal combustion engine

Info

Publication number: CN214741701U
Application number: CN201990001010.3U
Authority: CN
Inventors: 原田诚
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2018-09-14
Filing date: 2019-09-13
Publication date: 2021-11-16
Anticipated expiration: 2029-09-13
Also published as: JPWO2020054845A1; PH12021550543A1; WO2020054845A1; BR112021003582A2; JP7015936B2

Abstract

The utility model provides an internal-combustion engine, internal-combustion engine (28) have: a crankcase (31) which divides a crank chamber; a cylinder block (32) coupled to the crankcase (31) and guiding the linear reciprocating motion of the piston; a detection sensor (86) which has a detection end facing a detected body rotating around a rotation axis (Rx) and detects the rotation angle of the crankshaft based on the movement of the detected body; and a starter motor (29) which is disposed at a position offset from the cylinder block (32) around the rotation axis (Rx) along the outer surface of the crankcase (31) and drives the crankshaft in response to the supply of electric power. The detection sensor (86) is disposed in a space between the cylinder block (32) and the starter motor (29) along the outer surface of the crankcase (31). Thus, the internal combustion engine is provided, which contributes to the miniaturization of the crankcase and can favorably protect the detection sensor for detecting the rotation angle of the crankshaft.

Description

Internal combustion engine

Technical Field

The utility model relates to an internal-combustion engine, this internal-combustion engine have detected body and detection sensor, detected body is fixed in the bent axle and rotates around the rotation axis with the bent axle together, detection sensor has the sense terminal that faces with detected body, detects the rotation angle of bent axle based on the action of detected body.

Background

Patent document 1 discloses an internal combustion engine including a crank angle detection unit that detects a rotation angle of a crankshaft. The crank angle detection unit includes: a signal rotor fixed to the crankshaft and rotating around a rotation axis together with the crankshaft, the signal rotor having teeth on an outer periphery; and a detection sensor having a detection end facing the teeth of the signal rotor, for detecting a rotation angle of the crankshaft based on the operation of the signal rotor.

Documents of the prior art

Patent document

Patent document 1 Japanese laid-open patent publication No. 2015-129442

The detection sensor is disposed in a space in the crankcase. Therefore, although the detection sensor is protected from external disturbance by the crankcase, the crankcase becomes large. The upsizing of the crankcase results in an increased weight of the internal combustion engine. In addition, in the crankcase, the detection sensor is required to be protected from the engine oil.

SUMMERY OF THE UTILITY MODEL

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an internal combustion engine that can contribute to downsizing of a crankcase and can favorably protect a detection sensor that detects a rotation angle of a crankshaft.

According to the utility model discloses a first aspect has: a crankcase that partitions a crank chamber; a crankshaft supported rotatably about a rotation axis by the crankcase; a cylinder block coupled to the crankcase, and guiding a linear reciprocating motion of a piston connected to the crankshaft; a detected body fixed to the crankshaft and rotating together with the crankshaft around the rotation axis; a detection sensor having a detection end facing the object to be detected and detecting a rotation angle of the crankshaft based on an operation of the object to be detected; a starter motor disposed along an outer surface of the crankcase at a position offset from the cylinder block about the rotation axis, the starter motor driving the crankshaft in accordance with supply of electric power, wherein the detection sensor is disposed in a space sandwiched between the cylinder block and the starter motor along the outer surface of the crankcase,

the crankcase has a first half case body and a second half case body that are joined to each other on a mating surface orthogonal to a rotation axis of the crankshaft and define the crank chamber, and the crankcase is formed with: an oil supply passage disposed in the wall along the mating surface; and a mounting hole that passes through the wall body at a position offset from the oil supply passage in the axial direction of the crankshaft and that houses the detection sensor.

According to a second aspect, in addition to the configuration of the first aspect, the cylinder block and the starter motor are disposed in front and rear along an upper surface of the crankcase, and the detection sensor is disposed on the upper surface of the crankcase.

According to a third aspect, in the structure of the first or second aspect, the oil supply passage extends from a mating surface with the cylinder block around an axis of the crankshaft.

According to a fourth aspect, in the structure of the third aspect, the wall body has: an inner wall connected to the crank chamber and having the oil supply passage; an outer wall disposed apart from the inner wall at an outer side of the inner wall and contacting with outside air; the mounting hole is constituted by a first hole formed in the inner wall and a second hole formed in the outer wall coaxially with the first hole.

According to a fifth aspect, in addition to the structure of the first or second aspect, a first imaginary plane includes a cylinder axis defined in the cylinder block and is parallel to the rotation axis of the crankshaft, a second imaginary plane includes a central axis of the detection sensor and the rotation axis of the crankshaft, and the first imaginary plane and the second imaginary plane intersect at an acute angle.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, a third imaginary plane includes an axial center of the drive shaft of the starter motor and the rotation axis of the crankshaft, the third imaginary plane intersects the first imaginary plane at an acute angle, and the detection sensor is disposed between the first imaginary plane and the third imaginary plane.

According to a seventh aspect of the present invention, in the configuration of the first or second aspect, the detection sensor is disposed below an imaginary horizontal plane that contacts the starter motor from above.

According to an eighth aspect of the present invention, in addition to the configuration of the first or second aspect, a cover wall that is disposed behind the starter motor and that houses a breather chamber is formed in the crankcase.

According to a ninth aspect of the present invention, in the structure of the eighth aspect, an engine hanger connected to a vehicle body frame is formed on the cover wall.

According to the first aspect, the detection sensor is protected from the front by the cylinder block and from the rear by the starter motor around the rotation axis. Auxiliary machines can be arranged in a concentrated manner around the crankcase. Further, since the mounting hole of the detection sensor is disposed so as not to interfere with the oil supply passage formed in the crankcase, an increase in the size of the crankcase can be avoided when the detection sensor is disposed.

According to the second aspect, since the detection sensor is disposed on the upper surface of the crankcase, the detection sensor can be protected from external disturbances such as small stones bouncing off the road surface.

According to the fourth aspect, since the space is formed between the inner wall and the outer wall, the crankcase can be made lightweight.

According to the fifth aspect, since the detection sensor is disposed close to the cylinder block, the space around the crankcase can be effectively utilized.

According to the sixth aspect, the space around the crankcase can be effectively utilized.

According to the seventh aspect, the detection sensor can be protected by the starter motor.

According to the eighth aspect, the detection sensor can be further protected by the cover wall.

According to the ninth aspect, the detection sensor can be protected by the vehicle body frame when mounted on the vehicle.

Drawings

Fig. 1 is a side view schematically showing an appearance of a motorcycle as a saddle-ride type vehicle according to an embodiment of the present invention. (first embodiment)

Fig. 2 is an enlarged side view of the internal combustion engine. (first embodiment)

Fig. 3 is an enlarged plan view of the internal combustion engine as viewed from above. (first embodiment)

Fig. 4 is an enlarged cross-sectional view of the internal combustion engine viewed in a cross-section including the cylinder axis, the rotation axis of the crankshaft, and the axial centers of the main shaft and the counter shaft. (first embodiment)

Fig. 5 is an enlarged view of the dynamic valve mechanism as viewed in a cross section orthogonal to the crankshaft. (first embodiment)

Fig. 6 is an enlarged plan view schematically showing a mating surface of the second half case with the first half case. (first embodiment)

Fig. 7 is an enlarged sectional view of the first case half as viewed in a section parallel to a mating surface with the second case half. (first embodiment)

Description of the reference numerals

12: vehicle body frame

28: internal combustion engine

31: crankcase

32: cylinder block

36 a: engine hanger (first engine hanger)

41: first half case body

41 a: involution surface

42: second half case

42 a: involution surface

46: axial center (of drive shaft)

48: piston

51: crankshaft

78: wall body

78 a: inner wall

78b, and (3 b): outer wall and mantle wall

79: ventilation chamber

81: oil supply path

85: detected body (pulse ring)

86: detecting sensor (pulse sensor)

86 a: detection terminal

87: mounting hole

87 a: first hole

87 b: second hole

88 a: first imaginary plane (containing cylinder axis)

88 b: second imaginary plane (containing the central axis of the pulse sensor)

88 c: third imaginary plane (containing the axis of the drive shaft)

89: imaginary horizontal plane

C: cylinder axis

Cr: crank chamber

Rx: axis of rotation (of crankshaft)

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the front-rear direction, the up-down direction, and the left-right direction are directions viewed from a rider riding a motorcycle.

First embodiment

Fig. 1 schematically shows a motorcycle according to an embodiment of a saddle-ride type vehicle. The motorcycle 11 includes a body frame 12 and a body cover 13 attached to the body frame 12. The body frame 12 includes a head pipe 14, a main frame 15 extending rearward and downward from the head pipe 14, a pivot frame 16 coupled to a rear portion of the main frame 15 and extending downward, and a sheet frame 17 coupled to the main frame 15 at a front end and extending rearward and upward. A front fork 18 and a rod-shaped steering handle 19 are rotatably supported by the head pipe 14, and the front fork 18 supports the front wheel WF to be rotatable about the axle. The driver grips the left and right grips of the steering handle 19 when driving the motorcycle 11.

The vehicle body cover 13 includes a front cover 21 covering the head pipe 14 from the front, a leg shield 22 extending continuously downward from the front cover 21, and a main cover 23 covering the main frame 15 and the sheet frame 17. A passenger seat 24 is mounted on the main cover 23 above the sheet frame 17. When the motorcycle 11 is driven, the occupant rides on the occupant seat 24. The leg shield 22 covers the knees of the occupant from the front.

The swing arm 26 is connected to the body frame 12 to be swingable up and down around a pivot shaft 25 at the rear of the vehicle. The rear wheel WR is rotatably supported around the axle at the rear end of the swing arm 26. The rear cushion unit 27 is disposed between the sheet frame 17 and the swing arm 26 at a position away from the pivot shaft 25. The rear cushion unit 27 dampens vibrations transmitted from the rear wheel WR to the body frame 12 when the rear wheel WR moves up and down along with the ground.

An internal combustion engine 28 that generates a driving force transmitted to the rear wheel WR is mounted on the vehicle body frame 12 between the front wheel WF and the rear wheel WR. As shown in fig. 2, the internal combustion engine 28 includes an engine main body 28a that supports accessories such as a starter motor 29. The power of the internal combustion engine 28 is transmitted to the rear wheel WR via the transmission.

The engine main body 28a includes: a crankcase 31 supporting a crankshaft that generates power around a rotation axis Rx; a cylinder block 32 combined with the crankcase 31; and a cylinder head 33 coupled to the cylinder block 32. The starter motor 29 is disposed at a position offset from the cylinder block 32 about the rotation axis Rx along the outer surface of the crankcase 31, and drives the crankshaft in response to the supply of electric power.

In the crankcase 31, a first engine hanger 36a connected to a bracket 34 fixed to the main frame 15 by a bolt 35, and a second engine hanger 36b and a third engine hanger 36c vertically arranged along the rear end of the crankcase 31 and connected to the pivot frame 16 by a bolt 37 are formed at the rear side of the starter motor 29. Each

bolt

35, 37 has an axial center extending parallel to the rotation axis Rx.

An intake device 38 and an exhaust device 39 are connected to the cylinder head 33. The intake device 38 injects fuel from a fuel injection valve to air cleaned by the air cleaner to generate an air-fuel mixture, and supplies the air-fuel mixture to the engine main body 28 a. The exhaust device 39 guides exhaust gas from the engine main body 28a to the rear, purifies the exhaust gas, and exhausts the exhaust gas from the rear of the vehicle while muffling the exhaust gas.

As shown in fig. 3, the crankcase 31 includes: a first half case 41 and a second half case 42 that are coupled to each other by

mating surfaces

41a and 42a orthogonal to a rotation axis Rx of the crankshaft to define a crank chamber for accommodating a crank of the crankshaft; a left cover 43 coupled to the first case half body 41 with an engagement surface orthogonal to the rotation axis Rx of the crankshaft, and defining a generator room between the first case half body 41 and the left cover; and a right cover 44 coupled to the second case half body 42 through a mating surface orthogonal to the rotation axis Rx of the crankshaft, and defining a clutch chamber between the second case half body 42 and the right cover. The first half case 41, the second half case 42, and the right cover 44 are integrally coupled by long bolts inserted from the first half case 41, the second half case 42 being inserted through the bolts, and the bolts being screwed into the right cover 44. The first, second, and

third engine hangers

36a, 36b, and 36c are constituted by the first and

second case members

41 and 42, and bolts are inserted through the first and

second case members

41 and 42.

A support 45 for supporting the starter motor 29 is integrally formed with the first case half body 41. The starter motor 29 includes a case 29a that houses cylindrical bodies of the stator and the rotor, and a mounting piece 29b that protrudes from the case 29a and is coupled to the support body 45 of the first case half body 41 with a bolt. A driving force is generated between the rotor and the stator based on a magnetic force generated at the coil in response to the supply of electric power. The rotor is fixed to the drive shaft. The drive shaft has a shaft center 46 extending parallel to the rotational axis Rx of the crankshaft. The cylinder block 32 and the starter motor 29 are disposed forward and rearward along the upper surface of the crankcase 31.

As shown in fig. 4, the cylinder block 32 defines cylinder bores 47. A piston 47 is slidably fitted into the cylinder bore 47 along a cylinder axis C (a center axis of the cylinder bore). The cylinder axis C is inclined slightly forward and upward. The cylinder block 32 guides the linear reciprocating motion of the piston 48.

The cylinder head 33 defines a combustion chamber 49. The piston 48 is opposed to the cylinder head 33 and partitions a combustion chamber 49 between the piston and the cylinder head 33. The air-fuel mixture is introduced from the intake device 38 into the combustion chamber 49 in accordance with the opening and closing operation of the intake valve. The exhaust gas in the combustion chamber 49 is discharged through the exhaust device 39 in accordance with the opening/closing operation of the exhaust valve.

The crankshaft 51 has: a first crank arm 51a journalled to a bearing 52a assembled into the first case half 41; a second crank arm 51b journaled to a bearing 52b assembled into the second case half 42; a crank pin 53 extending parallel to the rotation axis Rx and joining the first crank arm 51a and the second crank arm 51b to each other. The crank pin 53 cooperates with the first and second crank arms 51a, 51b to form a crank between the bearings 52a, 52 b. The crank is housed in the crank chamber Cr. A large end of a connecting rod 54 extending from the piston 48 is rotatably connected to the crank pin 53. The connecting rod 54 converts the linear reciprocating motion of the piston 48 into a rotational motion of the crankshaft 51.

A valve operating mechanism 55 for transmitting power of the crankshaft 51 to the intake valve and the exhaust valve is coupled to the crankshaft 51 outside the bearing 52 a. The valve operating mechanism 55 includes: a camshaft 56 supported rotatably by the cylinder head 33 around an axis parallel to the rotation axis Rx of the crankshaft 51; a drive sprocket 57 fixed coaxially with the crankshaft 51; a driven sprocket 58 coaxially fixed to the camshaft 56; and a timing chain 59 wound around the drive sprocket 57 and the driven sprocket 58, moving along the endless path, and transmitting the rotational force of the crankshaft 51 from the drive sprocket 57 to the driven sprocket 58. When the crankshaft 51 rotates, the camshaft 56 rotates at a predetermined reduction gear ratio, and controls the opening and closing operations of the intake valve and the exhaust valve.

As shown in fig. 5, the dynamic valve mechanism 55 is assembled with: an idler pulley 61 supported rotatably about a rotation axis parallel to the rotation axis Rx of the crankshaft 51 in the cylinder block 32 and inscribed in the timing chain 59 between the drive sprocket 57 and the driven sprocket 58; a tensioner 62 that circumscribes the timing chain 59 so as to be freely displaceable along a virtual plane orthogonal to the rotation axis Rx of the crankshaft 51 between the idler pulley 61 and the drive sprocket 57, and adjusts the tension of the timing chain 59; a tensioner tappet 63 that applies a load to the tensioner 62 along an imaginary plane orthogonal to the rotation axis Rx.

The tensioner 62 has: an arm member 62a supported by the first half case 41 so as to be swingable about a swing axis Sx parallel to the rotation axis Rx of the crankshaft 51, and extending forward and rearward from the swing axis Sx; and a tension roller 62b supported by the tip end of the arm member 62a so as to be rotatable about a rotation axis parallel to the swing shaft Sx, and coming into contact with the timing chain 59 so as to be displaceable along a virtual plane orthogonal to the rotation axis Rx of the crankshaft 51. An acting point 62c at which a load of the tensioner tappet 63 acts from the tangential direction around the swing axis Sx is formed at the rear end of the arm member 62 a. The load of the tensioner tappet 63 acts on the tension roller 62b by the oscillation of the arm member 62 a. The tension of the timing chain 59 is adjusted according to the load of the tensioner lifter 63.

As shown in fig. 4, an Alternator (ACG)65 that generates electric power in accordance with rotation of the crankshaft 51 is coupled to the crankshaft 51 outside the bearing 52 a. The ACG65 includes: an outer rotor 66 fixed to the crankshaft 51 that penetrates the first half case 41 of the crankcase 31 and protrudes from the first half case 41; and an inner stator 67 surrounded by the outer rotor 66 and disposed around the crankshaft 51. The inner stator 67 is fixed to the left cover 43. An electromagnetic coil 67a is wound around the inner stator 67. The magnet 66a is fixed to the outer rotor 66. When the outer rotor 66 rotates relative to the inner stator 67, electric power is generated by the electromagnetic coil 67 a.

A starter gear 68 is fixed to the crankshaft 51 between the outer rotor 66 of the ACG65 and the bearing 52 a. The starter gear 68 has teeth 68a arranged in a ring shape coaxially with the rotation axis Rx of the crankshaft 51. As shown in fig. 2, the rotational power generated by the drive shaft of the starter motor 29 is transmitted to the starter gear 68 via the intermediate gear. Thus, rotation of the crankshaft 51 is caused at the time of starting the internal combustion engine 28.

As shown in fig. 4, a centrifugal clutch 69 that controls connection and disconnection with a multi-stage transmission (hereinafter, referred to as a "transmission") Mt is coupled to the crankshaft 51 outside the bearing 52 b. The centrifugal clutch 69 includes: a cylinder 69a which is coaxially attached to the crankshaft 51 and relatively rotatably supported by the crankshaft 51; a clutch outer 69b formed coaxially with the crankshaft 51 and coupled to the cylinder 69a so as to be relatively non-rotatable; and a clutch inner 69c that is disposed coaxially with the crankshaft 51 on the inner side of the clutch outer 69b and is coupled to the crankshaft 51 so as to be relatively non-rotatable. When a centrifugal force acts on the clutch inner 69c based on a predetermined rotation speed, the friction members come into contact between the clutch inner 69c and the clutch outer 69b, and the rotation of the clutch inner 69c is transmitted to the clutch outer 69b, that is, the cylindrical body 69 a. The drive gear 71 coupled to the cylinder 69a rotates about the rotation axis Rx in synchronization with the crankshaft 51.

An oil passage 73 extending from the tip along the rotation axis Rx (axial center) and connected to the discharge passage 72 in the crank pin 53 is formed in the second crank arm 51b of the crankshaft 51. The engine oil is introduced from the right cover 44 to the front end of the crankshaft 51, and is supplied to the contact area between the crank pin 53 and the connecting rod 54 via the oil passage 73.

The transmission Mt is housed in a transmission chamber Tr that is continuous with the crank chamber Cr and is partitioned by the crankcase 31. The transmission Mt includes a main shaft 74 and a counter shaft 75 having an axial center parallel to the axial center of the crankshaft 51. The main shaft 74 and the sub shaft 75 are rotatably supported by the first half case 41 and the second half case 42 via rolling bearings. The transmission Mt is configured as a so-called multi-stage clutch type multi-stage transmission.

A plurality of ratio gears 76 are supported on the main shaft 74 and the counter shaft 75. The transmission gear 76 is housed in the transmission chamber Tr. The speed change gear 76 has: a rotary gear 76a which is relatively rotatably and coaxially supported by the main shaft 74 or the auxiliary shaft 75; a fixed gear 76b fixed to the main shaft 74 so as to be non-rotatable relative thereto, and meshing with the corresponding rotary gear 76 a; the transmission gear 76c is supported by the main shaft 74 or the counter shaft 75 so as to be relatively non-rotatable and axially displaceable, and meshes with the corresponding rotary gear 76 a. The axial displacement of the rotating gear 76a and the fixed gear 76b is restricted. When the speed change gear 76c is linked to the rotary gear 76a by axial displacement, the relative rotation of the rotary gear 76a and the main shaft 74 or the counter shaft 75 is restricted. When the change gear 76c is engaged with the fixed gear 76b of the other shaft, rotational power is transmitted between the main shaft 74 and the counter shaft 75. When the change gear 76c is linked to the rotary gear 76a that meshes with the fixed gear 76b of the other shaft, rotary power is transmitted between the main shaft 74 and the counter shaft 75. In this way, by engaging a specific speed change gear 76 between the main shaft 74 and the counter shaft 75, the rotational power is transmitted from the main shaft 74 to the counter shaft 75 at a predetermined speed reduction ratio.

A drive sprocket 77a of a transmission device disposed outside the crankcase 31 is coupled to the counter shaft 75. The drive chain 77b is wound around the drive sprocket 77 a. The drive chain 77b transmits the rotational power of the drive sprocket 77a to the rear wheel WR.

As shown in fig. 6, the crankcase 31 has a wall 78 forming an upper wall of the crankcase 31 below the starter motor 29. Wall 78 includes an inner wall 78a in contact with crank chamber Cr and an outer wall 78b disposed outside inner wall 78a and apart from inner wall 78a and in contact with the outside air. Behind the starter motor 29, a ventilation chamber 79 is divided between the inner wall 78a and the outer wall 78 b. The breather chamber 79 is connected to the crank chamber Cr via small holes 79a formed by joining grooves formed in the

mating surfaces

41a, 42a of the first case half 41 and the second case half 42. A partition nozzle 79b is formed on the outer wall 78b at the upper end of the breather chamber 79, and the nozzle 79b partitions an outflow port connected to a breather pipe connected to the air cleaner. In the breather chamber 79, a labyrinth structure is established from the small hole 79a toward the outflow port of the nozzle 79 b. The outer wall 78b is continuous with the first engine pylon 36 a.

The inner wall 78a forms an oil supply passage 81 extending from the mating surface 31a of the cylinder block 32 around the rotation axis Rx of the crankshaft 51 along the mating surfaces of the first case half 41 and the second case half 42. The oil supply passage 81 includes a passage 81a formed by aligning grooves formed in the mating surfaces 41a and 42a of the first half case 41 and the second half case 42, respectively. As shown in fig. 3, the front end of the passage 81a is connected to a lateral passage 81c, and the lateral passage 81c is formed in the second case half body 42 in the vertical direction from the mating surface 42a and is connected to a front-rear passage 81b passing through the mating surface 31a of the cylinder block 32 and the crankcase 31. The front and rear passages 81b are connected to an oil pump (not shown) via a passage 82a extending along the mating surface 31a of the cylinder block 32 and the crankcase 31 and a passage 82b formed in the second case half 42 and leading to the oil strainer. A branch passage formed in the right housing 44 and leading to the oil passage 73 in the crankshaft 51 is connected to the passage 82 b. The rear end of the oil supply passage 81 penetrates the first half case 41, and is connected to a lateral passage 83 that opens to the outside of the first half case 41, as shown in fig. 5. Engine oil is supplied from the oil supply passage 81 to the dynamic valve mechanism 55.

As shown in fig. 4, a pulser ring 85 is attached to the crankshaft 51, and the pulser ring 85 includes a reluctance rotor 84(リラクター) arranged coaxially with the crankshaft 51 in a ring shape between the first crank arm 41a and the bearing 52 a. The impulse ring 85 is fixed to, for example, an outer surface of the first crank arm 51 a. The reluctance rotor 84 protrudes radially outward beyond the outer periphery of the first crank arm 51 a. The pulse ring 85 is formed of, for example, a magnetic body.

As shown in fig. 7, a pulse sensor (detection sensor) 86 having a detection end 86a facing the reluctance rotor 84 is attached to the crankcase 31, and detects the rotation angle of the crankshaft 51 based on the operation of the reluctance rotor 84. As shown in fig. 3, the first case half body 41 is formed with a mounting hole 87 into which the pulse sensor 86 is inserted through the wall body 78 at a position apart from the

mating surfaces

41a, 42 a. The mounting hole 87 includes a first hole 87a and a second hole 87b, the first hole 87a being formed in the inner wall 78a and divided by a cylindrical surface, the second hole 87b being formed in the outer wall 78b and divided by a cylindrical surface coaxial with the first hole 87 a.

As shown in fig. 2 and 3, the pulse sensor 86 is disposed along the outer surface of the crankcase 31 in a space sandwiched between the cylinder block 32 and the starter motor 29. A first imaginary plane 88a including the cylinder axis C defined in the cylinder block 32 and parallel to the rotation axis Rx of the crankshaft 51 and a second imaginary plane 88b including the center axis of the pulse sensor 86 and the rotation axis Rx of the crankshaft 51 intersect at an acute angle. The pulse sensor 86 is disposed between a first virtual plane 88a and a third virtual plane 88c, the third virtual plane 88c including the axial center of the drive shaft of the starter motor 29 and the rotation axis Rx of the crankshaft 51 and intersecting the first virtual plane 88a at an acute angle. The pulse sensor 86 is disposed below an imaginary horizontal plane 89 that contacts the starter motor 29 from above. The cylinder axis C and the center axis of the pulse sensor 86 are tilted forward with respect to a vertical plane orthogonal to the ground.

Next, the operation of the present embodiment will be described. The internal combustion engine 28 of the present embodiment is disposed at a position offset from the cylinder block 32 around the rotation axis Rx along the outer surface of the crankcase 51, and includes a starter motor 29 that drives the crankshaft 51 in response to the supply of electric power. The pulse sensor 86 is disposed along the outer surface of the crankcase 31 in a space sandwiched between the cylinder block 32 and the starter motor 29. Therefore, the pulse sensor 86 is protected from the front by the cylinder block 32 and from the rear by the starter motor 29 around the rotation axis Rx. The auxiliary machines are disposed around the crankcase 31.

In the internal combustion engine 28, a cylinder block 32 and a starter motor 29 are arranged in front and rear along the upper surface of a crankcase 31. Since the pulse sensor 86 is disposed between the cylinder block 32 and the starter motor 29 along the upper surface of the crankcase 31, the pulse sensor 86 can be protected from external disturbances such as stones bouncing off the road surface.

In the present embodiment, a mounting hole 87 is formed in crankcase 31, and this mounting hole 87 is inserted into pulse sensor 86 through wall body 78 at a position offset from oil supply passage 81 in the axial direction of crankshaft 51. Since the mounting hole 87 of the pulse sensor 86 is disposed so as not to interfere with the oil supply passage 81 formed in the crankcase 31, the size of the crankcase 31 is not increased in the disposition of the pulse sensor 86.

Wall 78 has: an inner wall 78a which is in contact with the crank chamber Cr and has an oil supply passage 81; and an outer wall 78b which is disposed outside the inner wall 78a so as to be spaced apart from the inner wall 78a and is in contact with the outside air. The mounting hole 87 is constituted by a first hole 87a formed in the inner wall 78a and a second hole 87b formed in the outer wall 78b coaxially with the first hole 87 a. Thus, a space is formed between the inner wall 78a and the outer wall 78b, and therefore the crankcase 31 is light in weight.

In the present embodiment, a first imaginary plane 88a and a second imaginary plane 88b intersect at an acute angle, the first imaginary plane 88a including the cylinder axis C defined by the cylinder block 32 and being parallel to the rotation axis Rx of the crankshaft 51, and the second imaginary plane 88b including the center axis of the pulse sensor 86 and the rotation axis Rx of the crankshaft 51. Since the pulse sensor 86 is disposed close to the cylinder block 32, the space around the crankcase 31 is effectively used.

The pulse sensor 86 of the present embodiment is disposed between the first virtual plane 88a and the third virtual plane 88c, and the third virtual plane 88c includes the axial center of the drive shaft of the starter motor 29 and the rotation axis Rx of the crankshaft 51 and intersects the first virtual plane 88a at an acute angle, so that the space around the crankcase 31 is effectively used.

The pulse sensor 86 is disposed below an imaginary horizontal plane 89 that contacts the starter motor 29 from above. Thus, the pulse sensor 86 is protected by the starter motor 29.

The outer wall 78b of the crankcase 31 is disposed rearward of the starter motor 29 and houses the breather chamber 79. The pulse sensor 86 is further protected by an outer wall 78b (hood wall) that expands along the vertical plane behind the starter motor 29.

The first engine hanger 36a connected to the body frame 12 is formed on the outer wall 78b (hood wall). The pulse sensor 86 is protected by the body frame 12.

Claims

1. An internal combustion engine having:

a crankcase (31) which defines a crank chamber (Cr);

a crankshaft (51) rotatably supported by the crankcase (31) about a rotation axis (Rx);

a cylinder block (32) coupled to the crankcase (31) and guiding a linear reciprocating motion of a piston (48) connected to the crankshaft (51);

a detected body (85) fixed to the crankshaft (51) and rotating together with the crankshaft (51) around the rotation axis (Rx);

a detection sensor (86) that has a detection end (86a) facing the detected body (85) and detects the rotation angle of the crankshaft (51) based on the operation of the detected body (85);

a starter motor (29) that is disposed at a position offset from the cylinder block (32) about the rotation axis (Rx) along the outer surface of the crankcase (31) and that drives the crankshaft (51) in accordance with the supply of electric power; it is characterized in that the preparation method is characterized in that,

the detection sensor (86) is disposed in a space sandwiched between the cylinder block (32) and the starter motor (29) along an outer surface of the crankcase (31),

the crankcase (31) has a first half case body (41) and a second half case body (42) that are joined to each other on mating surfaces (41a, 42a) orthogonal to a rotation axis (Rx) of the crankshaft (51) and that define the crank chamber (Cr), and the crankcase (31) has formed thereon: an oil supply passage (81) disposed in the wall body (78) along the mating surfaces (41a, 42 a); and a mounting hole (87) that penetrates the wall body (78) at a position that is offset from the oil supply passage (81) in the axial direction of the crankshaft (51), and that houses the detection sensor (86).

2. The internal combustion engine of claim 1,

the cylinder block (32) and the starter motor (29) are disposed in front and rear along the upper surface of the crankcase (32), and the detection sensor (86) is disposed on the upper surface of the crankcase (31).

3. An internal combustion engine according to claim 1 or 2,

the oil supply passage (81) extends from a mating surface of the cylinder block (32) around the axis of the crankshaft (51).

4. An internal combustion engine according to claim 3,

the wall (78) has: an inner wall (78a) that is in contact with the crank chamber (Cr) and that has the oil supply path (81); an outer wall (78b) which is disposed apart from the inner wall (78a) outside the inner wall (78a) and is in contact with outside air; the mounting hole (87) is configured by a first hole (87a) formed in the inner wall (78a) and a second hole (87b) formed in the outer wall (78b) coaxially with the first hole (87 a).

5. An internal combustion engine according to claim 1 or 2,

a first imaginary plane (88a) includes a cylinder axis (C) defined in the cylinder block (32) and is parallel to a rotation axis (Rx) of the crankshaft (51), a second imaginary plane (88b) includes a central axis of the detection sensor (86) and the rotation axis (Rx) of the crankshaft (51), and the first imaginary plane (88a) and the second imaginary plane (88b) intersect at an acute angle.

6. The internal combustion engine of claim 5,

a third imaginary plane (88c) includes an axial center (46) of a drive shaft of the starter motor (29) and a rotation axis (Rx) of the crankshaft (51), the third imaginary plane (88c) intersects the first imaginary plane (88a) at an acute angle, and the detection sensor (86) is disposed between the first imaginary plane (88a) and the third imaginary plane (88 c).

7. An internal combustion engine according to claim 1 or 2,

the detection sensor (86) is disposed below an imaginary horizontal plane (89) that is in contact with the starter motor (29) from above.

8. An internal combustion engine according to claim 1 or 2,

a cover wall (78b) that is disposed behind the starter motor (29) and that houses a breather chamber (79) is formed in the crankcase (31).

9. The internal combustion engine of claim 8,

an engine hanger (36a) connected to a vehicle body frame (12) is formed on the cover wall (78 b).