EP4357592A1

EP4357592A1 - Internal combustion engine and straddled vehicle

Info

Publication number: EP4357592A1
Application number: EP23193669.1A
Authority: EP
Inventors: Kenji Aoyagi; Kensuke Yamamoto
Original assignee: Yamaha Motor Co Ltd
Current assignee: Yamaha Motor Co Ltd
Priority date: 2022-10-18
Filing date: 2023-08-28
Publication date: 2024-04-24
Also published as: BR102023021566A2; TW202417736A; JP2024059165A

Abstract

There is disclosed an internal combustion engine (1) including a cylinder body (3); a cylinder head (4) connected with the cylinder body; a cylinder head cover (5) connected with the cylinder head; and a valvetrain provided in the cylinder head and the cylinder head cover; the internal combustion engine further including a nozzle (10) provided in the cylinder head cover and located so as to allow oil to be supplied to the valvetrain; the nozzle including a first nozzle portion (11) extending from a base end (10be) of the nozzle toward a tip end (10te) of the nozzle (10), and a second nozzle portion (12) extending from a tip end of the first nozzle portion (11) to the tip end of the nozzle (10) and having a cutout portion (12c), facing the valvetrain, formed as a result of the second nozzle portion (12) being partially cut out in the circumferential direction.

Description

Technical Field

The present invention relates to an internal combustion engine and a straddled vehicle.

Prior art

A straddled vehicle such as a motorcycle or the like may have an internal combustion engine (engine) mounted thereon such that a cylinder is inclined forward significantly. For example, Japanese Laid-Open Patent Publication No. Hei 4-81525 discloses a scooter-type motorcycle including an engine mounted on a swing unit such that a cylinder is inclined forward significantly.
In the motorcycle disclosed in Japanese Laid-Open Patent Publication No. Hei 4-81525 , a valvetrain chamber in a cylinder head is supplied with oil from an oil pipe extending forward in an area below a cylinder body and connected with a center of a top portion of the cylinder head. In the case where the oil is supplied to the valvetrain chamber in this manner, the oil is sufficiently supplied to a bottom portion of the valvetrain but is not sufficiently supplied to a top portion of the valvetrain.
Under such circumstances, it is conceivable to provide a nozzle above the valvetrain and to supply oil to the valvetrain via the nozzle. Japanese Laid-Open Patent Publication No. 2020-105969 shows a structure in which oil is supplied to the valvetrain via a nozzle provided inside a cylinder head cover.
However, regarding the structure in which the oil is supplied to the valvetrain via the nozzle provided in the cylinder head cover, it has been found out by the studies made by the present inventors that the following occurs in a state where the engine has a low temperature (that is, the oil also has a low temperature) and furthermore, the engine is rotated at a low rotation rate and the oil is injected in a small amount (e.g., in an idling state after cold start). The oil has a high viscosity, and therefore, the oil cannot be injected vigorously from a tip of the nozzle, and the oil may possibly not be supplied to a desired position in the valvetrain.

Description of the invention

An embodiment of the present invention made in light of the above-described problem has an object of providing an internal combustion engine capable of supplying oil in a preferred manner to a desired position in a valvetrain in a cylinder head even in a state where the oil has a relatively high viscosity.
This specification discloses an internal combustion engine and a straddled vehicle described in the following claims.

[Claim 1]

An internal combustion engine, comprising:

a cylinder body;
a cylinder head connected with the cylinder body;
a cylinder head cover connected with the cylinder head; and
a valvetrain provided in the cylinder head and the cylinder head cover,
wherein the internal combustion engine further includes a nozzle provided in the cylinder head cover and located so as to allow oil to be supplied to the valvetrain, and
wherein the nozzle includes a first nozzle portion extending from a base end of the nozzle toward a tip end of the nozzle, and a second nozzle portion extending from a tip end of the first nozzle portion to the tip end of the nozzle and having a cutout portion, facing the valvetrain, formed as a result of the second nozzle portion being partially cut out in the circumferential direction.

The internal combustion engine according to an embodiment of the present invention includes the nozzle provided in the cylinder head cover and located so as to allow oil to be supplied to the valvetrain. The nozzle includes the first nozzle portion extending from the base end of the nozzle toward the tip end of the nozzle, and the second nozzle portion extending from the tip end of the first nozzle portion to the tip end of the nozzle and having the cutout portion, facing the valvetrain, formed as a result of the second nozzle portion being partially cut out in the circumferential direction. In the internal combustion engine according to an embodiment of the present invention, when the oil has a relatively high viscosity and the engine is rotated at a relatively low rotation rate, the oil flows along a portion of the second nozzle portion that is not cut out and flows down from the tip end of the nozzle. The second nozzle portion has the cutout portion, facing the valvetrain, formed therein. Therefore, the oil having a high viscosity is guided to a desired position in the valvetrain without the nozzle interfering with a movable component of the valvetrain.

[Claim 2]

The internal combustion engine of Claim 1, wherein the cutout portion is formed to occupy a range of 70 degrees or larger in the circumferential direction at the tip end of the nozzle.
From the point of view of avoiding the interference between the movable component of the valvetrain and the nozzle, it is preferred that the cutout portion of the second nozzle portion is formed to occupy a range of 70 degrees or larger in the circumferential direction at the tip end of the nozzle.

[Claim 3]

The internal combustion engine of Claim 1 or 2, wherein the cutout portion is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end of the nozzle.
From the point of view of allowing the oil to flow down from the tip end of the nozzle in a preferred manner, it is preferred that the cutout portion of the second nozzle portion is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end of the nozzle.

[Claim 4]

The internal combustion engine of any one of Claims 1 to 3, wherein the cutout portion is formed to occupy a range, in the circumferential direction, enlarging from a base end toward a tip end of the second nozzle portion.
The cutout portion of the second nozzle portion may be formed to occupy a range, in the circumferential direction, enlarging from the base end toward the tip end of the second nozzle portion.

[Claim 5]

The internal combustion engine of any one of Claims 1 to 4, wherein the second nozzle portion has an inner circumferential surface of a tapering shape such that an inner diameter of the second nozzle portion increases from a base end toward a tip end of the second nozzle portion.
In the case where the inner circumferential surface of the second nozzle portion has a tapering shape such that the inner diameter of the second nozzle portion increases from the base end toward the tip end of the second nozzle portion, the oil is supplied in a more preferred manner when the oil is injected in a large amount (e.g., in a maximum amount).

{Claim 6]

A straddled vehicle, comprising the internal combustion engine of any one of Claims 1 to 5.

[Claim 7]

The straddled vehicle of Claim 6, wherein the nozzle is located above the valvetrain in a vertical direction.
An embodiment of the present invention provides an internal combustion engine capable of supplying oil in a preferred manner to a desired position in a valvetrain in a cylinder head even in a state where the oil has a relatively high viscosity.

Brief description of the drawings

FIG. 1 is a left side view schematically showing a motorcycle 100 according to an embodiment of the present invention.
FIG. 2 is a side view of an engine 1 included in the motorcycle 100.
FIG. 3 is a plan view of the engine 1.
FIG. 4 is a cross-sectional view of the engine 1 taken along line 4A-4A' in FIG. 3 .
FIG. 5 is a cross-sectional view of the engine 1 taken along line 5A-5A' in FIG. 4 .
FIG. 6 is a cross-sectional view of the engine 1 taken along line 6A-6A' in FIG. 4 .
FIG. 7 is a cross-sectional view of the engine 1 taken along line 7A-7A' in FIG. 4 .
FIG. 8 is a cross-sectional view schematically showing a nozzle 10 (left nozzle 10A) included in the engine 1, and is an enlarged view of the nozzle 10 and the vicinity thereof in FIG. 4 .
FIG. 9 is a cross-sectional view schematically showing the nozzle 10 (left nozzle 10A) included in the engine 1, and is an enlarged view of the nozzle 10 and the vicinity thereof in FIG. 6 .
FIG. 10 is a rear view of the nozzle 10 (left nozzle 10A).
FIG. 11 shows a structure in which a comparative example nozzle 910 is provided in a cylinder head cover 5.
FIG. 12 shows how oil is supplied to an axial end of an intake valve 21 via the nozzle 10.

Embodiments of the invention

Hereinafter, a straddled vehicle according to an embodiment of the present invention will be described with reference to the drawings. The straddled vehicle is a vehicle on which a rider rides while straddling. In the following description, a motorcycle will be described as an example of straddled vehicle according to an embodiment of the present invention. There is no limitation on the type of the motorcycle, and the motorcycle may be any vehicle of a so-called scooter type, a moped type, an off-road type, an on-road type or the like. The straddled vehicle according to an embodiment of the present invention is not limited to a motorcycle, and may be an ATV (All Terrain Vehicle), a quad bike or the like.
With reference to FIG. 1 , an overall structure of a motorcycle 100 according to this embodiment will be described. FIG. 1 is a left side view schematically showing the motorcycle 100. In the following description, the terms "front", "rear", "left", "right", "up" and "down" respectively refer to front, rear, left, right, up and down as seen from a rider sitting on a seat of the motorcycle 100. The terms "up" and "down" respectively refer to up and down in a vertical direction in a state where the motorcycle 100 is at a stop on a horizontal plane. The above-mentioned directions will also be used to describe components of an engine. Therefore, the terms "front", "rear", "left", "right", "up" and "down" used regarding the engine respectively refer to front, rear, left, right, up and down of the engine mounted on the motorcycle 100.
As shown in FIG. 1 , the motorcycle 100 includes a body frame 102 including a head pipe 101, a seat 103 supported by the body frame 102, an engine (internal combustion engine) 1 supported by the body frame 102, a handle 104 pivotably supported by the head pipe 101, a front wheel 105, and a rear wheel 106 drivable by the engine 1.
With reference to FIG. 2 through FIG. 7 , a structure of the engine 1 will be described. FIG. 2 and FIG. 3 are respectively a side view and a plan view of the engine 1. FIG. 4 is a cross-sectional view taken along line 4A-4A' in FIG. 3 . FIG. 5 , FIG. 6 and FIG. 7 are cross-sectional views respectively taken along lines 5A-5A', 6A-6A' and 7A-7A' in FIG. 4 . The terms "front", "rear", "left", "right", "up" and "down" shown in FIG. 2 through FIG. 7 refer to front, rear, left, right, up and down in a state where the engine 1 is mounted on the motorcycle 100.
The engine 1 is a four-stroke, water-cooled engine. The engine 1 includes a crankcase 2 (only shown in FIG. 2 ) accommodating a crankshaft (not shown), a cylinder body 3 connected with the crankcase 2, a cylinder head 4 connected with the cylinder body 3, a cylinder head cover 5 connected with the cylinder head 4, and a valvetrain (including intake valves 21, exhaust valves 22, and the like described below) provided in the cylinder head 4 and the cylinder head cover 5.
A transmission case 7 accommodating a transmission (e.g., a CVT (Continuously Variable Transmission)) is located to the left of the crankcase 2.
A cylinder 6 is formed in the cylinder body 3. The cylinder 6 extends along a cylinder axial line CA. The cylinder axial line CA is inclined forward significantly with respect to the vertical direction (up-down direction). That is, the cylinder 6 extends forward from the crankcase 2. In this embodiment, the term "forward" is used in a broad sense, and the expression that "the cylinder 6 extends forward" encompasses a case where the cylinder 6 extends forward in a horizontal direction and a case where the cylinder 6 is inclined with respect to the horizontal direction. In this embodiment, the engine 1 is a single-cylinder engine including one cylinder 6. Alternatively, the engine 1 may be a multicylinder engine including a plurality of cylinders.
The cylinder 6 accommodates a piston (not shown). The cylinder 6 demarcates a part of a combustion chamber 8. The piston is coupled with the crankshaft via a conrod (not shown). The cylinder body 3 and the crankcase 2 may be formed separately from each other, or may be formed integrally with each other.
The cylinder head 4 is located to the front of the cylinder body 3, and is connected with a front portion of the cylinder body 3. The cylinder head 4 has two intake ports 31 and two exhaust ports 32 formed therein. The two intake ports 31 each have an intake opening 31A opened toward the combustion chamber 8. Air to be absorbed into the combustion chamber 8 flows through the intake ports 31. The two exhaust ports 32 each have an exhaust opening 32A opened toward the combustion chamber 8. Air discharged from the combustion chamber 8 flows through the exhaust ports 32.
In the cylinder head 4 and the cylinder body 3, a water jacket 9, in which cooling water flows, is formed. The water jacket 9 includes a portion 9A formed in the cylinder head 4 and a portion 9B formed in the cylinder body 3.
The cylinder head cover 5 is located to the front of the cylinder head 4, and is connected with a front portion of the cylinder head 4. The cylinder head 4 and the cylinder head cover 5 may be formed separately from each other as shown in the figures, or may be formed integrally with each other.
The valvetrain of the engine 1 includes two intake valves 21, two exhaust valves 22, a cam shaft 23, and two locker arms 24.
The two intake valves 21 each open or close the corresponding intake opening 31A. The two exhaust valves 22 each open or close the corresponding exhaust opening 32A.
The cam shaft 23 is rotatably supported by the cylinder head 4. The cam shaft 23 crosses the cylinder axial line CA. The cam shaft 23 is located in a cam chamber 34 and a cam chain chamber 35. The cam chamber 34 is a space defined by the cylinder head 4 and the cylinder head cover 5. The cam chain chamber 35 is a space defined by the crankcase 2, the cylinder body 3, the cylinder head 4 and the cylinder head cover 5. In the example shown in the figures, the cam chain chamber 35 is located to the left of the cylinder 6. The cam chain chamber 35 may be located to the right of the cylinder 6. The cam chain chamber 35 and the cam chamber 34 are in communication with each other.
Each of the intake valves 21 and the corresponding exhaust valve 22 are in engagement with the cam shaft 23 via the corresponding locker arm 24. The intake valve 21 and the exhaust valve 22 are opened or closed in accordance with a rotation of the cam shaft 23. The number of the intake valve(s) 21 and the number of the exhaust valve(s) 22 are not limited to two as described as an example in this embodiment. For example, in the case where the number of the intake port(s) 31 is one and the number of the exhaust port(s) 32 is one, the number of the intake valve(s) 21 may also be one and the number of the exhaust valve(s) 22 may also be one.
The cam shaft 23 extends in a left-right direction. A driven sprocket (cam chain sprocket) 23S is attached to a left end of the cam shaft 23. The driven sprocket 23S is located in the cam chain chamber 35, and is rotatable integrally with the cam shaft 23. A cam chain (not shown) is wound around the driven sprocket 23S and a driving sprocket (not shown) attached to the crankshaft. The driving sprocket is located in the cam chain chamber 35, and is rotatable integrally with the crankshaft. The cam chain is associated with the crankshaft and the cam shaft 23.
The engine 1 further includes a plurality of (two in this embodiment) nozzles 10 provided in the cylinder head cover 5. The nozzles 10 are located so as to allow oil to be supplied to the valvetrain. As shown in FIG. 4 , the nozzles 10 are located above the valvetrain in the vertical direction. Hereinafter, among the two nozzles 10, a nozzle located to the left of the other nozzle may be referred to as a "left nozzle 10A", and a nozzle located to the right of the other nozzle may be referred to as a "right nozzle 10B", for the sake of convenience.
The left nozzle 10A is located to the front of, and above, the left intake valve 21. The position of the left nozzle 10A in the left-right direction is substantially the same as the position of the left intake valve 21 in the left-right direction. The right nozzle 10B is located to the front of, and above, the right intake valve 21. The position of the right nozzle 10B in the left-right direction is substantially the same as the position of the right intake valve 21 in the left-right direction.
With reference to FIG. 8, FIG. 9 and FIG. 10 , a structure of the nozzle 10 will be described. FIG. 8 and FIG. 9 are each a cross-sectional view schematically showing the nozzle 10 (left nozzle 10A). FIG. 8 is an enlarged view of the nozzle 10 and the vicinity thereof shown in FIG. 4 . FIG. 9 is an enlarged view of the nozzle 10 and the vicinity thereof shown in FIG. 6 . FIG. 10 is a rear view of the nozzle 10 (left nozzle 10A).
The nozzle 10 includes a first nozzle portion 11 and a second nozzle portion 12. A nozzle hole (hollow portion) 10a, through which oil flows, is formed in the entirety of the nozzle 10, that is, through both of the first nozzle portion 11 and the second nozzle portion 12. The nozzle hole 10a is in communication with an oil supply path 15 at a base end 10be of the nozzle 10. An axial line NA of the nozzle 10 extends rearward and slightly downward from the side of the base end 10be of the nozzle 10.
The first nozzle portion 11 extends from the base end 10be of the nozzle 10 toward a tip end late of the nozzle 10. The second nozzle portion 12 extends from a tip end of the first nozzle portion 11 to the tip end late of the nozzle 10. The second nozzle portion 12 is partially cut out in a circumferential direction. That is, the second nozzle portion 12 has a cutout portion 12c formed therein. The cutout portion 12c faces the valvetrain. In other words, the cutout portion 12c is formed at least below the second nozzle portion 12.
In this specification, the range of the second nozzle portion 12 occupied by the cutout portion 12c will be represented with angle θ (see FIG. 10 ) in the circumferential direction. In the example shown in the figures, the cutout portion 12c is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end 10te of the nozzle 10. As shown in FIG. 9 and FIG. 10 , the cutout portion 12c is formed to occupy a range, in the circumferential direction, enlarging from a base end toward a tip end of the second nozzle portion 12.
As shown in FIG. 8 , the first nozzle portion 11 has an inner diameter substantially the same in the entirety thereof. By contrast, the second nozzle portion 12 has a tapering shape such that an inner diameter of the second nozzle portion 12 increases from the base end toward the tip end of thereof.
As described above, with the structure in which oil is supplied to the valvetrain via a nozzle provided in the cylinder head cover, the following occurs in a state where the engine has a low temperature (that is, the oil also has a low temperature) and furthermore, the engine is rotated at a low rotation rate and the oil is injected in a small amount (e.g., in an idling state after cold start). The oil has a high viscosity, and therefore, the oil cannot be injected vigorously from a tip of the nozzle, and the oil may possibly not be supplied to a desired position in the valvetrain. It is conceivable to make the nozzle longer to guide the oil to a desired position. However, there are restrictions caused by the layout in the engine. For example, there may be an undesirable possibility that the longer nozzle and a movable component of the valvetrain interfere with each other. For this reason, the structure in which the nozzle is made longer may be unusable.
By contrast, the nozzle 10 included in the engine 1 according to this embodiment includes the first nozzle portion 11 extending from the base end 10be of the nozzle 10 toward the tip end 10te of the nozzle 10, and the second nozzle portion 12 extending from the tip end of the first nozzle portion 11 to the tip end late of the nozzle 10 having the cutout portion 12c, facing valvetrain, formed as a result of the second nozzle portion 12 being partially cut out in the circumferential direction. Therefore, with the engine 1 according to this embodiment, the oil flows as follows when the viscosity of the oil is relatively high and the rotation rate of the engine 1 is relatively low. As represented by the arrows in FIG. 10 , the oil flows along a portion of the second nozzle portion 12 that is not cut out and flows down from the tip end late of the nozzle 10. The second nozzle portion 12 has the cutout portion 12c facing the valvetrain. Therefore, the oil having a high viscosity is guided to a desired position in the valvetrain without the nozzle 10 interfering with the movable component of the valvetrain.
FIG. 11 shows a structure in which a comparative example nozzle 910 is provided in the cylinder head cover 5. The comparative example nozzle 910 has a nozzle hole 910 formed in the entirety thereof. The comparative example nozzle 910 does not have a cutout portion facing the valvetrain. That is, the comparative example nozzle 910 dose not have a portion corresponding to the second nozzle portion 12 in the nozzle 10 of the engine 1 according to this embodiment.
In the case where the comparative example nozzle 910 is provided, oil is injected vigorously from a tip of the nozzle 910 as represented with the arrow with the dotted line, after sufficient warm-up driving or when the rotation rate of the engine 1 is relatively high. Therefore, the oil is supplied in a sufficient amount to the axial end of the intake valve 21. However, when the viscosity of the oil is high and the rotation rate of the engine 1 is low, the oil cannot be injected vigorously from the tip of the nozzle 910 as represented by the arrow with the solid line. Therefore, the oil cannot be supplied in a sufficient amount to the axial end of the intake valve 21.
By contrast, referring to FIG. 12 , with the engine 1 according to this embodiment, when the viscosity of the oil is high and the rotation rate of the engine 1 is low, the oil flows along a portion of the second nozzle portion 12 that is not cut out and flows down from the tip end late of the nozzle 10. Therefore, the oil is supplied in a sufficient amount to the axial end of the intake valve 21. With the engine 1 according to this embodiment, while the oil is injected vigorously from the tip end late of the nozzle 10 (after sufficient warm-up driving or when the rotation rate of the engine 1 is relatively high), the oil may also be supplied to an area to the rear of the axial end of the intake valve 21. The oil supplied to the area to the rear of the intake valve 21, for example, reaches the cam shaft 23 and is splashed in the cylinder head 4 as droplets by the rotation of the cam shaft 23 to lubricate the inside of the cylinder head 4.
There is no specific limitation on the range (angle θ shown in FIG. 10 ) of the second nozzle 12 occupied by the cutout portion 12. From the point of view of avoiding the interference between the movable component of the valvetrain and the nozzle 10, it is preferred that the range occupied by the cutout portion 12c is of a certain size or larger. Specifically, from the above-described point of view, it is preferred that the cutout portion 12c is formed to occupy a range of 70 degrees or larger in the circumferential direction at the tip end late of the nozzle 10.
However, from the point of view of allowing the oil to flow down from the tip end late of the nozzle 10 in a preferred manner, it is preferred that the cutout portion 12c of the second nozzle portion 12 is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end late of the nozzle 10. In other words, it is preferred that the second nozzle 12 is formed such that the portion thereof other than the cutout portion 12c extends to be present in an area below a part of a lower half of the nozzle hole 10a.
The cutout portion 12c of the second nozzle portion 12 may be formed to occupy a range, in the circumferential direction, enlarging from the base end toward the tip end of the second nozzle portion 12 as described above as an example.
In the case where the second nozzle portion 12 has an inner circumferential surface of a tapering shape such that an inner diameter of the second nozzle portion 12 increases from the base end toward the tip end thereof, the oil is supplied in a more preferred manner when the oil is injected in a large amount (e.g., in a maximum amount).
The second nozzle portion 12 has a length Ls (see FIG. 9 ) that is not specifically limited. The length Ls is, for example, 200 or more of the entire length L (see FIG. 9 ) of the nozzle 10.
In this embodiment, the structure in which the engine 1 has two nozzles 10 is described as an example. The number of the nozzle (s) 10 is not limited to two. One, or three or more, nozzles 10 may be provided in the cylinder head cover 5 in accordance with the specifications of the valvetrain (the number of the valves, etc.).
There is no specific limitation on the method for producing the cylinder head cover 5 including the nozzles 10. The cylinder head cover 5 may be produced by, for example, casting. That is, the cylinder head cover 5 may be a cast product.
As described above, the internal combustion engine 1 according to an embodiment of the present invention includes the cylinder body 3; the cylinder head 4 connected with the cylinder body 3; the cylinder head cover 5 connected with the cylinder head 4; and the valvetrain provided in the cylinder head 4 and the cylinder head cover 5. The internal combustion engine 1 further includes the nozzle 10 provided in the cylinder head cover 5 and located so as to allow oil to be supplied to the valvetrain. The nozzle 10 includes the first nozzle portion 11 extending from the base end 10be of the nozzle 10 toward the tip end 10te of the nozzle 10, and the second nozzle portion 12 extending from the tip end of the first nozzle portion 11 to the tip end late of the nozzle 10 and having the cutout portion 12c, facing the valvetrain, formed as a result of the second nozzle portion 12 being partially cut out in the circumferential direction.
The internal combustion engine 1 according to an embodiment of the present invention includes the nozzle 10 provided in the cylinder head cover 5 and located so as to allow oil to be supplied to the valvetrain. The nozzle 10 includes the first nozzle portion 11 extending from the base end 10be of the nozzle 10 toward the tip end late of the nozzle 10, and the second nozzle portion 12 extending from the tip end of the first nozzle portion 11 to the tip end 10te of the nozzle 10 and having the cutout portion 12c, facing the valvetrain, formed as a result of the second nozzle portion 12 being partially cut out in the circumferential direction. In the internal combustion engine 1 according to an embodiment of the present invention, when the viscosity of the oil is relatively high and the rotation rate of the engine 1 is relatively low, the oil flows along the portion of the second nozzle portion 12 that is not cut out and flows down from the tip end late of the nozzle 10. The second nozzle portion 12 has the cutout portion 12c, facing the valvetrain, formed therein. Therefore, the oil having a high viscosity is guided to a desired position in the valvetrain without the nozzle 10 interfering with the movable component of the valvetrain.
In one embodiment, the cutout portion 12c is formed to occupy a range of 70 degrees or larger in the circumferential direction at the tip end 10te of the nozzle 10.
From the point of view of avoiding the interference between the movable component of the valvetrain and the nozzle 10, it is preferred that the cutout portion 12c of the second nozzle portion 12 is formed to occupy a range of 70 degrees or larger in the circumferential direction at the tip end 10te of the nozzle 10.
In one embodiment, the cutout portion 12c is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end late of the nozzle 10.
From the point of view of allowing the oil to flow down from the tip end 10te of the nozzle 10 in a preferred manner, it is preferred that the cutout portion 12c of the second nozzle portion 12 is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end late of the nozzle 10.
In one embodiment, the cutout portion 12c is formed to occupy a range, in the circumferential direction, enlarging from the base end toward the tip end of the second nozzle portion 12.
The cutout portion 12c of the second nozzle portion 12 may be formed to occupy a range, in the circumferential direction, enlarging from the base end toward the tip end of the second nozzle portion 12.
In one embodiment, the second nozzle portion 12 has an inner circumferential surface of a tapering shape such that an inner diameter of the second nozzle portion 12 increases from the base end toward the tip end of the second nozzle portion 12.
In the case where the inner circumferential surface of the second nozzle portion 12 has a tapering shape such that the inner diameter of the second nozzle portion 12 increases from the base end toward the tip end of the second nozzle portion 12, the oil is supplied in a more preferred manner when the oil is injected in a large amount (e.g., in a maximum amount).
A straddled vehicle according to an embodiment of the present invention includes the internal combustion engine 1 having any one of the above-described structures.
In one embodiment, the nozzle 10 is located above the valvetrain in the vertical direction.
An embodiment of the present invention provides an internal combustion engine capable of supplying oil in a preferred manner to a desired position in a valvetrain in a cylinder head even in a state where the oil has a relatively high viscosity. The internal combustion engine according to an embodiment of the present invention is preferably usable in any of various straddled vehicles.

Claims

An internal combustion engine (1), comprising:
a cylinder body (3);

a cylinder head (4) connected with the cylinder body (3) ;

a cylinder head cover (5) connected with the cylinder head (4); and

a valvetrain provided in the cylinder head (4) and the cylinder head cover (5),

wherein the internal combustion engine (1) further includes a nozzle (10) provided in the cylinder head cover (5) and located so as to allow oil to be supplied to the valvetrain, and

wherein the nozzle (10) includes a first nozzle portion (11) extending from a base end (lObe) of the nozzle (10) toward a tip end (10te) of the nozzle (10), and a second nozzle portion (12) extending from a tip end of the first nozzle portion (11) to the tip end of the nozzle (10) and having a cutout portion (12c), facing the valvetrain, formed as a result of the second nozzle portion (12) being partially cut out in the circumferential direction.
The internal combustion engine of claim 1, wherein the cutout portion (12c) is formed to occupy a range of 70 degrees or larger in the circumferential direction at the tip end (10te) of the nozzle (10).
The internal combustion engine of claim 1 or 2, wherein the cutout portion (12c) is formed to occupy a range smaller than 180 degrees in the circumferential direction at the tip end (10te) of the nozzle (10).
The internal combustion engine of any one of claims 1 to 3, wherein the cutout portion (12c) is formed to occupy a range, in the circumferential direction, enlarging from a base end toward a tip end of the second nozzle portion (12).
The internal combustion engine of any one of claims 1 to 4, wherein the second nozzle portion (12) has an inner circumferential surface of a tapering shape such that an inner diameter of the second nozzle portion (12) increases from a base end toward a tip end of the second nozzle portion (12).
A straddled vehicle, comprising the internal combustion engine (10) of any one of claims 1 to 5.
The straddled vehicle of claim 6, wherein the nozzle (10) is located above the valvetrain in a vertical direction.