JP7504166B2 - Internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine.

Conventionally, a structure has been disclosed in which a crank angle sensor is placed above and in front of the crankshaft and attached to the crankcase (see, for example, Patent Document 1).

International Publication No. 2018/180014

Incidentally, in order to reduce the size and weight of an internal combustion engine mounted on a saddle-type vehicle or the like (particularly to reduce the protrusion around the clutch), the side of the crankcase is sometimes inclined (cut at an angle) relative to the front-rear direction. The side of the crankcase is also a mating surface (joint surface) with a cover member attached to the crankcase. If this joint surface is inclined relative to the front-rear direction, when the cover member is fastened in the vehicle width direction, the cover member may shift along the joint surface, causing a positional shift in the front-rear direction. This results in a structure in which it is difficult to align the relative positions between the detection object supported on the crankcase side and the crank angle sensor supported on the cover member side, and there is a risk of variation in the detection accuracy of the crank angle sensor.
On the other hand, in recent years, research and development has been conducted on weight reduction that contributes to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy. In this technology for weight reduction, the positional deviation of the crank angle sensor supported on the cover member side is an issue.

The present invention provides an internal combustion engine that can reduce size and weight by cutting the side of the crankcase at an angle, while suppressing misalignment of the crank angle sensor supported on the cover member side. The aim is to ultimately contribute to energy efficiency.

As a means for solving the above problem, a first aspect of the present invention is an internal combustion engine including a crankcase (22) that houses a crankshaft (21) whose central axis of rotation (C1) is aligned along the vehicle width direction, a cover member (41) that covers the outside of the crankcase (22) in the vehicle width direction, a detectable body (51) that rotates with the rotation of the crankshaft (21), and a crank angle sensor (55) that is supported by the cover member (41) and detects the rotation of the detectable body (51), in which a joint surface (41a) between the crankcase (22) and the cover member (41) is inclined in the fore-and-aft direction with respect to a plane (S1) perpendicular to the vehicle width direction, and the crank angle sensor (55) is arranged to face the detectable body (51) in the vehicle up-and-down direction.
According to this configuration, the joint surface between the crankcase and the cover member (which is also the outer surface of the crankcase) is inclined in the front-rear direction with respect to a plane perpendicular to the vehicle width direction. This prevents the crankcase from protruding outward in the vehicle width direction on one side of the crankcase in the front or rear of the vehicle width direction (the case member side). This reduces the size of the crankcase when it is molded, making it smaller, lighter, and less expensive. Even when the crankcase is made smaller, the crank angle sensor can be attached to the cover member to reduce the impact on the freedom of placement of the crank angle sensor.
If the joint surface between the crankcase and the cover member is inclined relative to the front-rear direction, when the cover member is attached and fastened in the vehicle width direction, the position of the cover member may shift in the front-rear direction along the inclined joint surface. However, even if the relative positions of the crankcase and the cover member shift in the front-rear direction, the crank angle sensor faces the detected body in the vehicle up-down direction, so changes in the clearance (gap) between the crank angle sensor and the detected body in the opposing direction are suppressed.
That is, if the crank angle sensor faces the object to be detected in the fore-aft direction, a positional deviation of the cover member in the fore-aft direction directly changes the clearance between the crank angle sensor and the object to be detected, which tends to affect the accuracy of crank angle detection. On the other hand, if the crank angle sensor and the object to be detected face each other in the vertical direction of the vehicle, even if a positional deviation of the cover member occurs in the fore-aft direction, a positional deviation occurs between the crank angle sensor and the object to be detected in a direction intersecting the opposing direction, so that the change in the clearance is small and the effect on the accuracy of crank angle detection can be suppressed.
Therefore, the crank angle can be detected with high accuracy while reducing the size of the internal combustion engine.

A second aspect of the present invention is a crankcase (22) according to the first aspect, further comprising a cylinder portion (23) protruding upward and forward from an upper portion of the crankcase (22), and in a side view seen from the vehicle width direction, the crank angle sensor (55) is disposed in a range (H1) between a first angle reference line (L1) passing through a rotation center axis (C1) of the crankshaft (21) and extending parallel to the vehicle up-down direction, and a second angle reference line (L2) passing through the rotation center axis (C1) and extending parallel to a cylinder axis (C2) along the protruding direction of the cylinder portion (23).
According to this configuration, the crank angle sensor is disposed in an angle range extending from above the object to the front, tilted upward and forward like the cylinder section, so that it is easy to connect the wiring routed from above the engine to the crank angle sensor. Also, it is possible to reduce interference between the crank angle sensor and the clutch and transmission disposed at the rear of the crankcase, ensuring a degree of freedom in the placement of the crank angle sensor.

A third aspect of the present invention is a crankcase (22) of the first or second aspect, further comprising a cylinder portion (23) protruding upward and forward from an upper portion of the crankcase (22), and when a first longitudinal reference line (L3) and a second longitudinal reference line (L4) parallel to a cylinder axis (C2) along the protruding direction of the cylinder portion (23) in a side view seen from the vehicle width direction are arranged as tangents respectively touching the front and rear of the outer circumferential edge of the detectable body (51), the crank angle sensor (55) is arranged in a range (H2) sandwiched between the first longitudinal reference line (L3) and the second longitudinal reference line (L4) in a side view.
According to this configuration, the crank angle sensor is arranged so as to be aligned on the outer side of the cylinder portion in the vehicle width direction, so that the crank angle sensor can be made inconspicuous and the influence of external disturbances can be suppressed.

A fourth aspect of the present invention is any one of the first to third aspects, wherein the joint surface (41 a) is inclined so as to be located more inward in the vehicle width direction toward the rear, and the crank angle sensor (55) is disposed forward of the rotational center axis (C1) of the crankshaft (21).
According to this configuration, the joint surface of the cover member is inclined so as to be positioned inward in the vehicle width direction toward the rear, so that when the cover member is fastened, the position of the cover member will be shifted toward the rear. In this case, if the crank angle sensor is disposed forward of the axis of the crankshaft, the crank angle sensor and the detected object will approach each other even if the cover member is shifted. Therefore, the variation in the detection accuracy of the crank angle sensor can be suppressed compared to when the crank angle sensor and the detected object are separated from each other.

A fifth aspect of the present invention is any one of the first to fourth aspects, further comprising a cylinder portion (23) protruding upward and forward from an upper portion of the crankcase (22), and in a side view seen from the vehicle width direction, the crank angle sensor (55) is arranged at an angle closer to vertical than a cylinder axis (C2) along the protruding direction of the cylinder portion (23).
With this configuration, the installation angle of the crank angle sensor is closer to vertical behind the cylinder axis. Therefore, even if the cover member is misaligned in the fore-aft direction, the change in the clearance between the crank angle sensor and the object to be detected is smaller, thereby minimizing the effect on the accuracy of crank angle detection.

In a sixth aspect of the present invention, in any one of the first to fifth aspects, the crank angle sensor (55) is disposed adjacent to the joint surface (41a) in the vehicle width direction.
According to this configuration, the crank angle sensor is disposed near the joint surface, which prevents the area around the crank angle sensor from becoming enlarged in the vehicle width direction, thereby making it possible to downsize the internal combustion engine. "Adjacent to the joint surface" means, for example, that the crank angle sensor is disposed as close to the joint surface as possible without protruding outward in the vehicle width direction from the outermost side of the cover member.

A seventh aspect of the present invention is any one of the first to sixth aspects, wherein the detected body (51) is supported by a transmission member (37) attached to the crankshaft (21).
According to this configuration, since the detected object is supported on the transmission member attached to the crankshaft, it is possible to ensure the diameter dimension of the support part for the detected object based on the size of the transmission member. Also, the transmission member and the detected object can be disposed as close as possible. Therefore, compared to the case where the detected object is directly supported on the crankshaft, the support structure for the detected object can be simplified and the internal combustion engine can be made smaller.

An eighth aspect of the present invention is any one of the first to seventh aspects, wherein the crank angle sensor (55) is arranged in a recess (65) formed on the vehicle width direction outer side of the cover member (41), and a sensor fixing portion (63) for fixing the crank angle sensor (55) to the cover member (41) is arranged in the recess (65), as well as a cover fixing portion (45) for fixing the cover member (41) to the crankcase (22).
According to this configuration, by providing the cover fixing part together with the sensor fixing part in the recess in which the crank angle sensor is disposed, it is possible to reduce the protrusion of each fixing part and thereby to miniaturize the internal combustion engine. In addition, since the cover fixing part is disposed near the crank angle sensor, it is possible to easily ensure the positioning accuracy of the crank angle sensor.

The present invention provides an internal combustion engine that can reduce size and weight by cutting the side of the crankcase at an angle, while minimizing misalignment of the crank angle sensor supported on the cover member side.

FIG. 2 is a right side view of the engine according to the embodiment of the present invention. FIG. 2 is an enlarged view of a main part of FIG. 1 . FIG. 3 is a right side view of FIG. 2 with the right case cover removed. FIG. 2 is a plan view of a main part of the engine. This is a cross-sectional view taken along line VV of Figure 2. 11 is an explanatory diagram showing a positional deviation of a pulser sensor as viewed from the side; FIG.

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the directions of front, rear, left and right are the same as those in a vehicle equipped with an internal combustion engine of the embodiment unless otherwise specified. In addition, in the appropriate places in the drawings used in the following description, an arrow FR indicating the front of the vehicle, an arrow LH indicating the left side of the vehicle, an arrow UP indicating the top of the vehicle, and a line CL indicating the center of the left and right sides of the vehicle body are shown.

The engine (internal combustion engine) E shown in Figures 1 to 5 is mounted on the body of a saddle-type vehicle such as a motorcycle, and outputs a driving force for traveling. The engine E is, for example, a parallel multi-cylinder engine (for example, a parallel four-cylinder engine) with multiple cylinders arranged in the vehicle width direction (vehicle left-right direction). The engine E is configured as a power unit integrated with a clutch and a transmission. The engine E has a rotation center axis (crank axis) C1 of the crankshaft 21 aligned in the left-right direction (vehicle width direction). The engine E has a cylinder section 23 protruding diagonally forward and upward from the front upper part of the crankcase 22. The line C2 in the figure indicates an axis (cylinder axis) along the protruding direction of the cylinder section 23 in a side view. The cylinder axis C2 corresponds to a straight line when the cylinder center axis is viewed from the side. In the embodiment, "side view" means "side view from the vehicle width direction".

Referring to FIG. 1, the cylinder section 23 includes, in order from the crankcase 22 side, a cylinder body 24, a cylinder head 25, and a head cover 26. The cylinder body 24, the cylinder head 25, and the head cover 26 are stacked in a direction along the cylinder axis C2. An intake port 25a (see FIG. 4) for each cylinder opens at the rear upper part of the cylinder head 25, and an exhaust port 25b for each cylinder opens at the front lower part of the cylinder head 25. In the figure, the reference numeral 25c indicates the joint surface between the cylinder body 24 and the cylinder head 25, and the reference numeral 25d indicates the joint surface between the cylinder head 25 and the head cover 26. Each joint surface 25c, 25d is a plane perpendicular to the cylinder axis C2.

Referring to Figures 2 and 3, the crankcase 22 is divided, for example, in the vertical direction into an upper case 22a and a lower case 22b. A cylinder body 24 is integrally formed with the upper front part of the upper case 22a. An oil pan 27 is attached below the lower case 22b. An oil filter 28 is attached to the front of the lower case 22b.

The crankcase 22 houses the crankshaft 21 in the front and the clutch device 31 and the transmission 34 in the rear. The clutch device 31 is housed in the right rear part of the crankcase 22 and is covered by a right case cover 41 from the outside (right side) in the vehicle width direction. The clutch device 31 is a multi-plate clutch, and its axial direction is aligned with the vehicle width direction. The transmission 34 has a well-known configuration with a group of speed change gears between the main shaft and the countershaft, and the axial directions of the main shaft and the countershaft are aligned with the vehicle width direction. The rotational power of the crankshaft 21 is transmitted to the clutch device 31 via a centrifugal clutch 37 (described later), and is transmitted from the clutch device 31 to the transmission 34 where it is changed in speed, and then transmitted from the left rear part of the crankcase 22 to the drive wheels via, for example, a chain-type transmission mechanism.

Referring also to FIG. 4, a right case cover 41 is removably attached to the right side of the crankcase 22. The joint surface 41a between the right case cover 41 and the crankcase 22 is inclined relative to a plane S1 perpendicular to the vehicle width direction so that the rear side is positioned inward in the vehicle width direction. This prevents the crankcase 22 from protruding to the right at the rear of the crankcase 22. As a result, the size of the crankcase 22 when molded is reduced, and the crankcase 22 and therefore the engine E can be made smaller, lighter, and more cost-effective.

The right case cover 41 is formed so that its thickness in the vehicle width direction increases toward the rear as the right end of the crankcase 22 shifts inward in the vehicle width direction toward the rear. The rear part of the right case cover 41 ensures a thickness (depth) in the vehicle width direction, ensuring space to accommodate the clutch device 31. The dimensions of the crankcase 22 and therefore the engine E in the vehicle width direction are kept to a minimum from the perspective of compactness. For this reason, it is difficult to ensure space in the crankcase 22 to place the pulsar sensor 55, which will be described later, and so in this embodiment, the pulsar sensor 55 is placed in the right case cover 41. In this case, there is concern that a misalignment of the right case cover 41 may affect the detection accuracy of the pulsar sensor 55.

Referring to Figures 2, 3, and 5, the pulsar sensor (crank angle sensor) 55 is attached to the upper front part of the right case cover 41. The pulsar sensor 55 extends linearly along the radial direction of the crankshaft 21, and has a detection part 56 at its tip on the crank axis C1 side. The pulsar sensor 55 is attached at an angle to the vertical direction (the vehicle up-down direction).

A thin, disc-shaped pulsar ring 51 is disposed on the right end of the crankshaft 21. The pulsar ring 51 is attached so as to overlap the outer side in the vehicle width direction of a transmission member (e.g., centrifugal clutch 37) supported on the right end of the crankshaft 21. The member to which the pulsar ring 51 is attached is a member that always rotates integrally with the crankshaft 21. The transmission member to which the pulsar ring 51 is attached is not limited to the centrifugal clutch 37, and may be the primary drive gear 38, etc.

The detection portion 56 of the pulsar sensor 55 is disposed radially opposite to the outside of the pulsar ring 51. The pulsar ring 51 and the pulsar sensor 55 constitute a rotation sensor that detects the rotation of the crankshaft 21.

The centrifugal clutch 37 connects and disconnects the power transmission between the crankshaft 21 and the primary drive gear 38. When the rotation speed of the crankshaft 21 is less than a specified value, the centrifugal clutch 37 is in a disconnected state that blocks the power transmission, and does not transmit the driving force of the crankshaft 21 to the primary drive gear 38. When the rotation speed of the crankshaft 21 is equal to or greater than a specified value, the centrifugal clutch 37 is in a connected state that allows power transmission, and allows the driving force of the crankshaft 21 to be transmitted to the primary drive gear 38. By providing this centrifugal clutch 37, it is possible to start and stop the vehicle without the need to manually operate the clutch device 31.

The clutch device 31 is, for example, a wet multi-plate clutch and a normally closed clutch. When a specified operational input is made via an operating cable, hydraulic pressure, or the like in response to the occupant's clutch operation, the clutch device 31 enters a disconnected state in which power transmission is interrupted. When the operational input is released, the clutch device 31 returns to a connected state in which power transmission is possible due to the spring force of the built-in clutch spring. The operational input is not limited to only the occupant's clutch operation, but may also include the driving of an actuator such as an electric motor.

The clutch device 31 is fitted with a primary driven gear 39 that meshes with the primary drive gear 38 of the crankshaft 21. The primary drive gear 38 and the primary driven gear 39 constitute the primary reduction mechanism of the engine E. The primary driven gear 39 has an outer diameter equal to the maximum diameter of the clutch device 31, and its front end is overlapped with the rear end of the pulsar ring 51 that is coaxial with the crankshaft 21 in a side view. In other words, the outer dimensions of the pulsar ring 51 can be made as large as possible, so that the change in the clearance between the pulsar sensor 55 and the pulsar ring 51 is small, particularly when the position of the pulsar sensor 55 is shifted in the tangential direction of the pulsar ring 51, and this has an effect on the detection accuracy of the pulsar sensor 55.

Referring to FIG. 3, the pulsar ring 51 includes a disk-shaped annular body 51a and a number of reluctors 51b extending radially from the outer periphery of the annular body 51a. Each reluctor 51b is a protrusion integrally formed on the outer periphery of the annular body 51a, and protrudes radially outward beyond the outer periphery of the centrifugal clutch 37. The pulsar ring 51 is made of carbon steel or other steel material (magnetic material). The pulsar ring 51 is flat and perpendicular to the crank axis C1, and the multiple reluctors 51b are aligned in a row along the circumferential direction of the center of the crank axis C1.

The multiple reluctors 51b are arranged at equal intervals in the circumferential direction on the outer periphery of the pulsar ring 51. A reluctor-free area 52 is provided in a part of the circumferential direction of the outer periphery of the pulsar ring 51, where the reluctors 51b have been removed in a predetermined circumferential range. In other words, the multiple reluctors 51b are arranged at equal intervals in the circumferential direction in the range of the pulsar ring 51 excluding the reluctor-free area 52. The circumferential width of the reluctor-free area 52 (the distance between a pair of reluctors 51b on both sides of the reluctor-free area 52) is set to an integer multiple of the distance between the reluctors 51b arranged at equal intervals in the range excluding the reluctor-free area 52.

The detection part 56 at the tip of the pulsar sensor 55 is arranged facing the radially outer tip surface of each reluctor 51b from the radially outer side. The pulsar sensor 55 periodically changes its magnetism to generate a pulse signal depending on the presence or absence of the reluctor 51b to be detected. That is, the pulsar sensor 55 generates a pulse signal according to the rotation of the crankshaft 21. The detection result (pulse signal) of the pulsar sensor 55 is sent to the ECU (Engine Control Unit), which is the control device of the engine E. For example, if the change in the rotation speed (change in angular velocity) of the crankshaft 21 exceeds a threshold value during a preset number of cycles, the ECU infers a misfire in the engine E. Since the reluctor 51b is not present in the reluctor-absent region 52 of the pulsar ring 51, the period of the pulse signal generated by the pulsar sensor 55 changes. This allows the rotation position of the crankshaft 21 and therefore the stroke of the engine E to be detected.

Referring to Figures 2 to 5, the pulsar sensor 55 is inserted into a sensor insertion hole 61 drilled in the right case cover 41 and attached to the right case cover 41. The pulsar sensor 55 is composed of a rotation sensor that uses a magnetoresistance effect element such as a GMR (Giant Magneto Resistance). The pulsar sensor 55 is held in the right case cover 41 in an attitude that is tilted with respect to the up-down direction (vertical direction) of the vehicle. The pulsar sensor 55 is located in the upper front part of the right case cover 41 in an area that overlaps with the cylinder portion 23 in a side view.

The tip of the pulsar sensor 55, which detects magnetic bodies, faces inside the right case cover 41 (inside the crankcase 22). The pulsar sensor 55 has its most sensitive detection axis 55a (corresponding to the central axis of the main body of the pulsar sensor 55) oriented (intersecting) with the crank axis C1. The pulsar sensor 55 outputs a specified electrical signal depending on the presence or absence of a magnetic body detected on the orbit of the reluctor 51b. The pulsar sensor 55 outputs a pulse signal that identifies the rotational angle position of the crankshaft 21.

A sensor mounting seat 62 for mounting the pulser sensor 55 is formed on the upper front part of the right case cover 41. The sensor mounting seat 62 is a flat surface parallel to the left-right direction, inclined downward toward the front in a side view, and faces upward toward the front in the direction perpendicular to the surface. The sensor mounting seat 62 has a rectangular shape that includes the periphery of the opening of the circular sensor insertion hole 61. The cylindrical main body of the pulser sensor 55 is inserted into the sensor insertion hole 61 along its depth direction (the normal direction of the mounting seat 62).

The pulsar sensor 55 is provided with a fixing flange 57 on the base end side of the main body, and a coupler 58 for connecting an external harness. The fixing flange 57 is in the form of a plate perpendicular to the central axis 55a of the main body. The fixing flange 57 has, for example, a part in the circumferential direction protruding outward to form a fastening portion 57a. The fixing flange 57 abuts against the sensor mounting seat 62 when the main body is inserted into the sensor insertion hole 61 (sensor mounting state). In this state, the fastening portion 57a is fastened by a bolt 57b to a screw hole portion formed in the sensor mounting seat 62, thereby fixing the pulsar sensor 55 to the case right cover 41. The screw hole portion has a screw hole parallel to the sensor insertion hole 61, and is formed, for example, rearward and outward of the sensor insertion hole 61 in the vehicle width direction. The sensor fixing portion 63 for fixing the pulsar sensor 55 to the case right cover 41 is configured by including the fastening portion 57a, the bolt 57b, and the screw hole portion.

The sensor mounting seat 62 is formed above and in front of the crank axis C1. A recess 65 is formed in the upper front part of the case right cover 41 by cutting out the outer surface in a rectangular shape in side view. The recess 65 has a sensor mounting seat 62 that slopes downward toward the front in side view, front and rear walls 66, 67 that rise from the front and rear ends of the sensor mounting seat 62 at right angles to the sensor mounting seat 62, and an inner wall 68 that rises from the inner end of the sensor mounting seat 62 in the vehicle width direction at right angles to the sensor mounting seat 62. The protruding portion of the pulsar sensor 55 attached to the sensor mounting seat 62 toward the outside of the crankcase 22 (e.g., coupler 58) is arranged so as to overlap the edge 42 of the upper front part of the case right cover 41 in side view.

The case right cover 41 is fixed to the right side of the crankcase 22 by a plurality of fastening parts 43 arranged on the periphery in a side view. The bolt tightening direction (bolt axial direction) of each fastening part 43 is parallel to the vehicle width direction. Of the plurality of fastening parts 43, one fastening part 44 (and the bolt 44a used for the fastening part 44) located at the front upper part of the case right cover 41 is located generally inside the recess 65. The fastening part 44 inside the recess 65 is arranged so as to overlap in a side view with the working space (a virtual space extending the bolt 57b toward the head side) K1 (see FIG. 2) when attaching and detaching the bolt 57b for fixing the sensor. The cover fixing part 45 that fixes the case right cover 41 to the crankcase 22 is configured inside the recess 65, including the fastening part 44, the bolt 44a, and the corresponding screw hole part on the crankcase 22 side.

Whereas the joint surface 41a of the case right cover 41 is inclined relative to the front-to-rear direction in a plan view, the fastening bolts 43a of the case right cover 41 are parallel to the vehicle width direction. For this reason, when the bolts 43a are tightened, the case right cover 41 may shift along the joint surface 41a within the range of the tolerance of the case positioning structure such as the positioning pin. In other words, when the case right cover 41 is tightened toward the inside in the vehicle width direction, the case right cover 41 may shift in position to one side in the front-to-rear direction (the rear side in this embodiment) along the inclination of the joint surface 41a.

When the position of the right case cover 41 shifts in the front-rear direction, the relative position of the pulsar sensor 55 with respect to the pulsar ring 51 also shifts in the front-rear direction. At this time, if the pulsar sensor 55 faces the pulsar ring 51 in the front-rear direction, the positional shift of the right case cover 41 directly affects the clearance between the pulsar sensor 55 and the pulsar ring 51. As a result, if the clearance between the pulsar sensor 55 and the pulsar ring 51 exceeds the appropriate range, it affects the accuracy of crank angle detection.

If the pulsar sensor 55 is located directly above or below the pulsar ring 51, even if the right case cover 41 moves in the front-to-rear direction (in this case, the tangential direction), the clearance between the pulsar sensor 55 and the pulsar ring 51 will hardly change. The detection section 56 at the tip of the pulsar sensor 55 is sufficiently larger than the tip surface of each reluctor 51b, so even if the pulsar sensor 55 moves in the tangential direction within the tolerance range, the relative position of the pulsar sensor 55 to the pulsar ring 51 will hardly change. Therefore, a misalignment of the pulsar sensor 55 in the tangential direction has little effect on the detection accuracy of the crank angle. Furthermore, if the pulsar sensor 55 is located above the pulsar ring 51, the wiring required to connect to the vehicle's control device, etc., can be short.

From the above, the best position for the pulsar sensor 55 is directly above the pulsar ring 51, but to avoid the fastening portion 44 and bolt 44a near the pulsar sensor 55, the pulsar sensor 55 is positioned in this embodiment with a slight forward tilt. Note that at the rear of the right case cover 41, the cup-shaped clutch cover portion that covers the clutch device 31 from the outside in the vehicle width direction protrudes outward in the vehicle width direction, so positioning the pulsar sensor 55 with a rearward tilt poses the problem of interference with the clutch cover portion.

If the pulsar sensor 55 and the pulsar ring 51 face each other in the vertical direction, there is little change in the clearance between the pulsar sensor 55 and the pulsar ring 51 even if the position of the right case cover 41 shifts in the front-rear direction. Even if the pulsar sensor 55 is positioned at an angle to the vertical direction, the change in the clearance between the pulsar sensor 55 and the pulsar ring 51 when the pulsar sensor 55 moves in the front-rear direction is suppressed compared to when the pulsar sensor 55 is positioned facing the inclination direction of the joint surface 41a in side view (the direction in which the inclination of the joint surface 41a is greatest relative to a plane perpendicular to the vehicle width direction; in this embodiment, the front-rear direction).

Referring to FIG. 6, for example, if the pulser sensor 55 is positioned at an angle relative to the up-down and front-rear directions, the front-rear misalignment Y1 of the pulser sensor 55 is broken down into a misalignment R1 in the radial direction of the pulser ring 51 (the direction in which the pulser sensor 55 faces the pulser ring 51) and a misalignment R2 in the tangential direction. In this case, the change in the radial clearance is not zero, but compared to when the pulser sensor 55 faces the front-rear direction, the change in the radial clearance is smaller.

Referring to FIG. 3, the pulser sensor 55 is disposed at a position overlapping the cylinder section 23 in a side view. In the figure, line L1 indicates a first reference line that passes through the crank axis C1 and extends in the vertical direction in a side view, and line L2 indicates a second reference line that passes through the crank axis C1 and extends parallel to the cylinder axis C2 in a side view. The pulser sensor 55 is disposed in an angle range H1 between the first reference line L1 and the second reference line L2 in a side view.

In addition, line L3 in the figure indicates a third reference line that is parallel to the cylinder axis C2 and touches the outer periphery of the pulsar ring 51 (the circumference connecting the tips of the retractors) from the front side in a side view, and line L4 indicates a fourth reference line that is parallel to the cylinder axis C2 and touches the outer periphery of the pulsar ring 51 from the rear side in a side view. The pulsar sensor 55 is disposed in the fore-and-aft range H2 between the third reference line L3 and the fourth reference line L4 in a side view.

The pulsar sensor 55 is positioned forward of the crank axis C1 in a side view, and above and rearward of the cylinder axis C2. The pulsar sensor 55 is tilted forward so that the upper side is located forward in the vertical direction in a side view. The forward tilt angle of the pulsar sensor 55 is an angle that is closer to vertical than the cylinder axis C2 in a side view, and the pulsar sensor 55 is positioned facing as far up and down as possible. The pulsar sensor 55 is positioned with a slight forward tilt so that it does not overlap with the cover fastening bolt 44a in a side view.

As described above, the engine E in the above embodiment is an internal combustion engine that includes a crankcase 22 that houses a crankshaft 21 whose crank axis C1 is aligned in the vehicle width direction, a right case cover 41 that covers the outside of the crankcase 22 in the vehicle width direction, a pulsar ring 51 that rotates with the rotation of the crankshaft 21, and a pulsar sensor 55 that is supported by the right case cover 41 and detects the rotation of the pulsar ring 51. The joint surface 41a between the crankcase 22 and the right case cover 41 is inclined in the front-rear direction with respect to a plane S1 perpendicular to the vehicle width direction, and the pulsar sensor 55 is positioned to face the pulsar ring 51 in the vehicle up-down direction.

According to this configuration, the joint surface 41a between the crankcase 22 and the right case cover 41 (which is also the outer surface of the crankcase 22) is inclined in the front-rear direction with respect to a plane S1 perpendicular to the vehicle width direction. This prevents the crankcase 22 from protruding outward in the vehicle width direction on one side (the right case cover 41 side) of the crankcase 22 in the front or rear vehicle width direction. This reduces the size of the crankcase 22 when it is molded, making it possible to reduce the size and weight and reduce costs. Even when the crankcase 22 is made smaller, the pulsar sensor 55 can be attached to the right case cover 41 to reduce the impact on the freedom of arrangement of the pulsar sensor 55.
If the joint surface 41a between the crankcase 22 and the right case cover 41 is inclined relative to the front-rear direction, when the right case cover 41 is attached and fastened in the vehicle width direction, the position of the right case cover 41 may shift in the front-rear direction along the inclined joint surface 41a. However, even if the relative positions of the crankcase 22 and the right case cover 41 shift in the front-rear direction, the pulsar sensor 55 faces the pulsar ring 51 in the vehicle up-down direction, so changes in the clearance between the pulsar sensor 55 and the pulsar ring 51 in the opposing direction are suppressed.
That is, if the pulsar sensor 55 faces the pulsar ring 51 in the front-rear direction, any misalignment of the case right cover 41 in the front-rear direction will directly result in a change in the clearance between the pulsar sensor 55 and the pulsar ring 51, which is likely to affect the accuracy of crank angle detection. On the other hand, if the pulsar sensor 55 and the pulsar ring 51 face each other in the vertical direction of the vehicle, even if the case right cover 41 is misaligned in the front-rear direction, a misalignment occurs between the pulsar sensor 55 and the pulsar ring 51 in a direction intersecting the opposing direction, so the change in clearance is small and the effect on the accuracy of crank angle detection can be suppressed.
Therefore, the crank angle can be detected with high accuracy while reducing the size of the internal combustion engine.

The above-mentioned engine E is provided with a cylinder portion 23 that protrudes upward and forward from the upper part of the crankcase 22, and in a side view from the vehicle width direction, the pulser sensor 55 is disposed in a range H1 sandwiched between a first reference line L1 that passes through the crank axis C1 and extends parallel to the vehicle vertical direction, and a second reference line L2 that passes through the crank axis C1 and extends parallel to the cylinder axis C2 along the protruding direction of the cylinder portion 23.
According to this configuration, the pulsar sensor 55 is disposed at an angle ranging from above to the front of the pulsar ring 51, tilted upward and forward like the cylinder section 23, making it easier to connect wiring routed from above the engine to the pulsar sensor 55. Also, interference between the pulsar sensor 55 and the clutch and transmission disposed at the rear of the crankcase 22 is suppressed, ensuring freedom in the placement of the pulsar sensor 55.

In the above-mentioned engine E, which has a cylinder portion 23 that protrudes upward and forward from the upper part of the crankcase 22, when viewed from the side in the vehicle width direction, a third reference line L3 and a fourth reference line L4 that are parallel to the cylinder axis C2 along the protruding direction of the cylinder portion 23 are positioned as tangents that respectively contact the front and rear of the outer peripheral edge of the pulsar ring 51, the pulsar sensor 55 is positioned in the range H2 sandwiched between the third reference line L3 and the fourth reference line L4 in the side view.
According to this configuration, the pulsar sensor 55 is arranged so as to be aligned on the outer side of the cylinder portion 23 in the vehicle width direction, so that the pulsar sensor 55 can be made inconspicuous and the influence of external disturbances can be suppressed.

In the engine E, the joint surface 41a is inclined so as to be positioned inward in the vehicle width direction toward the rear, and the pulsar sensor 55 is disposed forward of the crank axis C1.
According to this configuration, the joint surface 41a of the right case cover 41 is inclined so as to be positioned inward in the vehicle width direction toward the rear, so that when the right case cover 41 is fastened, the position of the right case cover 41 will shift rearward. In this case, if the pulsar sensor 55 is disposed forward of the axis of the crankshaft 21, the pulsar sensor 55 and the pulsar ring 51 will move closer to each other even if the right case cover 41 shifts in position. Therefore, the variation in the detection accuracy of the pulsar sensor 55 can be suppressed compared to when the pulsar sensor 55 and the pulsar ring 51 are separated from each other.

The engine E is provided with a cylinder portion 23 that protrudes upward and forward from the upper part of the crankcase 22, and when viewed from the side in the vehicle width direction, the pulser sensor 55 is positioned at an angle closer to vertical than the cylinder axis C2 that runs along the protruding direction of the cylinder portion 23.
With this configuration, the installation angle of the pulser sensor 55 becomes closer to vertical behind the cylinder axis C2, so that even if the right case cover 41 is misaligned in the fore-and-aft direction, the change in the clearance between the pulser sensor 55 and the pulser ring 51 is smaller, thereby minimizing the impact on the accuracy of crank angle detection.

In the engine E, the pulsar sensor 55 is disposed adjacent to the joint surface 41a in the vehicle width direction.
According to this configuration, the pulsar sensor 55 is disposed near the joint surface 41a, which prevents the periphery of the pulsar sensor 55 from becoming enlarged in the vehicle width direction, thereby making it possible to miniaturize the internal combustion engine. "Adjacent to the joint surface 41a" means, for example, that the pulsar sensor 55 is disposed as close to the joint surface 41a as possible without protruding outward in the vehicle width direction from the outermost side of the right case cover 41.

In the engine E, the pulsar ring 51 is supported by a transmission member (centrifugal clutch 37 ) attached to the crankshaft 21 .
According to this configuration, the pulsar ring 51 is supported on the transmission member attached to the crankshaft 21, so that the diameter dimension of the support portion of the pulsar ring 51 can be ensured based on the size of the transmission member. Also, the transmission member and the pulsar ring 51 can be disposed as close as possible to each other. Therefore, compared to the case where the pulsar ring 51 is directly supported on the crankshaft 21, the support structure of the pulsar ring 51 can be simplified, and the internal combustion engine can be made more compact.

In the above-mentioned engine E, the pulsar sensor 55 is arranged in a recess 65 formed on the vehicle widthwise outer side of the right case cover 41, and a sensor fixing portion 63 for fixing the pulsar sensor 55 to the right case cover 41 is arranged in the recess 65, as well as a cover fixing portion 45 for fixing the right case cover 41 to the crankcase 22.
According to this configuration, by providing the cover fixing part 45 together with the sensor fixing part 63 in the recess 65 in which the pulsar sensor 55 is disposed, it is possible to reduce the size of the internal combustion engine by suppressing the protrusion of each fixing part 63, 45. In addition, since the cover fixing part 45 is disposed near the pulsar sensor 55, it is possible to easily ensure the positioning accuracy of the pulsar sensor 55.

The present invention is not limited to the above embodiment, and for example, the internal combustion engine of the present embodiment may be applied to a saddle-ride type vehicle other than a motorcycle. The saddle-ride type vehicle includes all vehicles on which a driver straddles the vehicle body, and includes not only motorcycles (including motorized bicycles and scooter-type vehicles), but also three-wheeled vehicles (including vehicles with one front wheel and two rear wheels, as well as vehicles with two front wheels and one rear wheel) or four-wheeled vehicles (such as four-wheeled buggies). The internal combustion engine may also be applied to a vehicle including an electric motor as a prime mover. The engine type is not limited to an in-line four-cylinder engine, and may be a multi-cylinder engine with three or less cylinders or five or more cylinders, a V-type engine, or a single-cylinder engine.
The configurations in the above-described embodiments are merely examples of the present invention, and various modifications are possible without departing from the gist of the present invention, such as replacing the components of the embodiments with well-known components.

E. Engine (internal combustion engine)
21 crankshaft 22 crankcase 23 cylinder portion 31 clutch device 34 transmission 37 centrifugal clutch (transmission member)
41 Case right cover (cover member)
41a: Joint surface 45: Cover fixing portion 51: Pulsar ring (detection object)
55 Pulsar sensor (crank angle sensor)
63 Sensor fixing portion 65 Recess C1 Crank axis (rotation center axis)
C2 Cylinder axis H1, H2 Range L1 First reference line (First angle reference line)
L2 Second reference line (second angle reference line)
L3 Third reference line (first front-rear reference line)
L4 Fourth reference line (second front-rear reference line)
S1 Plane perpendicular to the vehicle width direction

Claims (8)

A crankcase (22) that houses a crankshaft (21) whose rotational center axis (C1) is aligned along the vehicle width direction;
A cover member (41) that covers the outer side of the crankcase (22) in the vehicle width direction;
a detection object (51) that rotates in association with the rotation of the crankshaft (21);
a crank angle sensor (55) supported by the cover member (41) and configured to detect rotation of the detection object (51);
In an internal combustion engine comprising:
A joint surface (41 a) between the crankcase (22) and the cover member (41) is inclined in the front-rear direction with respect to a plane (S1) perpendicular to the vehicle width direction,
The crank angle sensor (55) is disposed so as to face the object to be detected (51) in the vertical direction of the vehicle. A cylinder portion (23) protruding forward and upward from an upper portion of the crankcase (22),
2. The internal combustion engine according to claim 1, wherein, in a side view seen from a vehicle width direction, the crank angle sensor (55) is disposed in a range (H1) sandwiched between a first angle reference line (L1) that passes through a rotation central axis (C1) of the crankshaft (21) and extends parallel to a vehicle up-down direction, and a second angle reference line (L2) that passes through the rotation central axis (C1) and extends parallel to a cylinder axis (C2) along a protruding direction of the cylinder portion (23). A cylinder portion (23) protruding forward and upward from an upper portion of the crankcase (22),
When a first longitudinal reference line (L3) and a second longitudinal reference line (L4) parallel to a cylinder axis (C2) along the protruding direction of the cylinder portion (23) in a side view seen from the vehicle width direction are disposed as tangents that respectively contact the front and rear of the outer circumferential edge of the detection object (51),
3. The internal combustion engine according to claim 1, wherein the crank angle sensor (55) is disposed in a range (H2) between the first longitudinal reference line (L3) and the second longitudinal reference line (L4) in a side view. The joint surface (41a) is inclined so as to be positioned inward in the vehicle width direction toward the rear side,
2. The internal combustion engine according to claim 1, wherein the crank angle sensor (55) is disposed forward of a rotational center axis (C1) of the crankshaft (21). A cylinder portion (23) protruding forward and upward from an upper portion of the crankcase (22),
2. The internal combustion engine according to claim 1, wherein, in a side view seen in a vehicle width direction, the crank angle sensor (55) is disposed at an angle closer to vertical than a cylinder axis (C2) along a protruding direction of the cylinder portion (23). The internal combustion engine according to claim 1, wherein the crank angle sensor (55) is disposed adjacent to the joint surface (41a) in the vehicle width direction. The internal combustion engine according to claim 1, wherein the object to be detected (51) is supported by a transmission member (37) attached to the crankshaft (21). The crank angle sensor (55) is disposed in a recess (65) formed on the outer side of the cover member (41) in the vehicle width direction,
2. The internal combustion engine according to claim 1, wherein a sensor fixing portion (63) that fixes the crank angle sensor (55) to the cover member (41) is arranged in the recess (65), and a cover fixing portion (45) that fixes the cover member (41) to the crankcase (22) is arranged in the recess (65).

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