JP2024025032A - Oil passage arrangement structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration capable of cooling a knocking sensor while enhancing a knocking detection function by arranging the knocking sensor close to a combustion chamber, make combustion appropriate through highly accurate knocking detection, and contribute to alleviation or reduction of an effect of a climate change by reducing discharge amount of harmful substances.

SOLUTION: An internal combustion engine 4 includes: a crank case 40; a cylinder block 42 connected to the crank case and forming a cylinder part 42a; a cylinder head 43 that is connected to the cylinder block and in which an intake port 45 and a discharge port 46 are formed; and a knocking sensor 80 provided in the cylinder block and detecting knocking. In an oil passage arrangement structure for the internal combustion engine, the cylinder block includes a cylinder block inner oil supply passage 91 to which oil is supplied from the crank case side, and the cylinder block includes a support part 81 for mounting at least part of the knocking sensor to face the cylinder block inner oil supply passage.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an oil passage arrangement structure for an internal combustion engine, and more particularly to an oil passage arrangement structure that contributes to cooling a knock sensor.

Efforts aimed at mitigating or reducing the effects of climate change have been ongoing, and research on reducing emissions of harmful substances is being conducted to achieve this goal.
Even in internal combustion engines, efforts are being made to reduce emissions of harmful substances by reducing NOx, SOx, etc. by optimizing combustion in the combustion chamber by controlling ignition timing, but when installing a knock sensor in a water-cooled internal combustion engine, For example, Patent Document 1 below discloses a system in which a knock sensor is disposed through a cooling water passage to contribute to cooling of the knock sensor.
However, when installing a knock sensor in an air-cooled internal combustion engine equipped with air-cooling fins, the knock sensor is cooled by air cooling from the surface of the internal combustion engine, so in order to improve cooling performance, it is necessary to place the knock sensor in a position far from the combustion chamber, which is the heat source. It is conceivable to arrange a knock sensor. However, as the distance from the combustion chamber increases, knocking in the combustion chamber cannot be detected with high accuracy.
Therefore, it is desired to cool the knock sensor in a manner that allows the knock sensor to be placed closer to the combustion chamber and to enable highly accurate detection of knocking in the combustion chamber.

Patent No. 406226 (Figures 2 to 6)

By the way, in order to reduce emissions of harmful substances and optimize combustion in internal combustion engines, it is a challenge to optimize combustion in the combustion chamber by controlling ignition timing through highly accurate knocking detection. .
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to arrange a knock sensor close to a combustion chamber so that the knock sensor can be cooled while improving the knock detection function. Furthermore, by reducing emissions of harmful substances, it contributes to mitigating or reducing the effects of climate change.

In order to solve the above problems, the oil passage arrangement structure for an internal combustion engine of the present invention is as follows:
a crankcase in which a crankshaft is rotatably supported;
a cylinder block connected to the crankcase and forming a cylinder portion;
a cylinder head connected to the cylinder block and having an intake port and an exhaust port;
An internal combustion engine including a knock sensor that is provided in the cylinder block and detects knocking,
The cylinder block is provided with an internal cylinder block supply oil passage through which oil is supplied from the crankcase side,
The oil passage arrangement structure for an internal combustion engine is characterized in that the cylinder block is provided with a support portion on which at least a part of the knock sensor (80) is attached facing the supply oil passage in the cylinder block.

According to the above configuration,
Since the knock sensor is mounted on the support part facing the cylinder block internal supply oil passage provided in the cylinder block, the knock sensor is cooled by the oil before the oil cools the surroundings of the combustion chamber and the camshaft. You can reduce the heat. As a result, the knock sensor can be disposed close to the combustion chamber and the knock sensor can be cooled while improving the knock detection function.
By controlling the ignition timing through highly accurate knocking detection, it is possible to optimize combustion in the combustion chamber, which in turn contributes to mitigating or reducing the effects of climate change by reducing emissions of harmful substances.

According to a preferred embodiment of the invention:
An oil inlet in the support portion through which oil is supplied to the cylinder block internal supply oil passage is located below an oil outlet in the support portion through which oil is discharged from the cylinder block internal supply oil passage.
In this way, since the oil outlet is located at a higher position than the oil inlet, it is possible to create a structure in which oil bubbles in the supply oil passage in the cylinder block at the support part can be easily discharged. Since oil bubbles are prevented from remaining in the oil supply path, the knock sensor can be effectively cooled.

According to a preferred embodiment of the invention:
The oil outlet is connected to a mating surface supply oil path formed on a mating surface of the cylinder block and the cylinder head, and the oil discharged from the oil outlet passes through the mating surface supply oil path. Since oil passes between the combustion chamber and the knock sensor, it is possible to create a structure in which heat is less likely to be transferred to the knock sensor, thereby improving the cooling performance of the knock sensor.

According to a preferred embodiment of the invention:
A gasket having a lower thermal conductivity than the cylinder block is interposed between the supply oil passage in the cylinder block and the knock sensor in the support part, and the knock sensor has a thermal conductivity lower than that of the cylinder block. Since the knock sensor is insulated by a gasket with a low temperature, it is possible to create a structure in which the temperature of the knock sensor is difficult to rise.As a result, the knock sensor is easily cooled by wind from outside the internal combustion engine, and the cooling performance of the knock sensor is improved.

According to the oil passage arrangement structure for an internal combustion engine of the present invention,
Since the knock sensor is mounted on the support part facing the cylinder block internal supply oil passage provided in the cylinder block, the knock sensor is cooled by the oil before the oil cools the surroundings of the combustion chamber and the camshaft. You can reduce the heat. As a result, the knock sensor can be disposed close to the combustion chamber and the knock sensor can be cooled while improving the knock detection function.
Controlling ignition timing through highly accurate knocking detection makes it possible to optimize combustion in the combustion chamber, which in turn contributes to mitigating or reducing the effects of climate change by reducing emissions of harmful substances.

FIG. 1 is a schematic right side view of a motorcycle equipped with a power unit having an oil passage arrangement structure for an internal combustion engine according to the present embodiment. FIG. 3 is a right side view of the internal combustion engine of the power unit from the crankcase to the head cover. FIG. 3 is a right side view taken out of the cylinder block of the internal combustion engine shown in FIG. 2; FIG. 4 is a right side view of the cylinder block shown in FIG. 3 with the knock sensor removed. FIG. 4 is a schematic cross-sectional view taken along the line VV in FIGS. 3 and 4, showing the state in which the knock sensor is installed. FIG. 4 is a front view of the cylinder block taken along the line VI-VI in FIGS. 2, 3, and 4. FIG. 4 is a rear view of the cylinder block taken along arrow VII-VII in FIGS. 3 and 4. FIG. FIG. 7 is a right side cross-sectional view of the internal combustion engine taken along arrows VIII-VIII in FIG. 6 and passing through the connecting portion between the first oil passage and the cylinder head mating surface supply oil passage.

An oil passage arrangement structure for an internal combustion engine according to an embodiment of the present invention will be described based on FIGS. 1 to 8.
Note that the directions such as front, back, left, right, top, and bottom in the description of this specification and the claims are based on the direction of a vehicle equipped with a power unit including an internal combustion engine according to this embodiment. In this embodiment, the vehicle is specifically a scooter-type motorcycle (hereinafter simply referred to as a "two-wheeled motorcycle").
Further, in the figure, arrow FR indicates the front of the vehicle, LH indicates the left side of the vehicle, and UP indicates the upper side of the vehicle.

FIG. 1 shows a schematic right side view of a motorcycle 1 equipped with a power unit 3 having an oil passage arrangement structure for an internal combustion engine according to the present embodiment.
In the motorcycle 1, a front body portion 1F and a rear body portion 1R are connected via a low floor portion 1C, and a body frame 2, which forms the skeleton of the vehicle body, is generally composed of a down tube 21 and a main pipe 22.
That is, the down tube 21 extends downward from the head pipe 20 on the front part 1F of the vehicle body, and the down tube 21 is bent horizontally at the lower end and extends rearward under the floor part 1C, and at the rear end, a pair of left and right main pipes 22 are formed. The main pipe 22 is bent approximately horizontally at a predetermined height and extends rearward through a rising portion 22a that rises diagonally rearward from the connecting portion.

A fuel tank and a storage box (not shown) are supported by the main pipe 22, and the passenger seat 11 is arranged above it.
On the other hand, in the front part 1F of the vehicle body, a handle 12 is provided above and supported pivotally by a head pipe 20, and a front fork 13 extends downward, and a front wheel 14 is supported pivotally at the lower end of the front fork 13.

A bracket 23 is protruded from the rising portion 22a of the main pipe 22, and a power unit side bracket 33 is attached to the bracket 23 via a link member 24, so that the swing type power unit (hereinafter simply referred to as "power unit") 3 is attached to the rear wheel. It is connected and supported with 15 so that it can swing up and down.
That is, the motorcycle 1 of this embodiment employs an upper link support structure for the power unit 3.

The power unit 3 is provided with a forced air-cooled, single-cylinder, four-stroke cycle internal combustion engine 4 at the front of a unit case 30, and the front of the unit case 30 constitutes a crankcase 40 of the internal combustion engine 4. The internal combustion engine 4 has a crankcase 40 rotatably supporting a crankshaft 41 having an axis in the vehicle width direction.
The internal combustion engine 4 also includes a cylinder block 42 connected to the crankcase 40 and forming a cylinder portion 42a, a cylinder head 43 connected to the cylinder block 42 and having an intake port 45 and an exhaust port 46 formed therein, and the cylinder head 43. The cylinder block 42, the cylinder head 43, and the head cover 44 are installed in the power unit 3 in an attached position with the cylinder block 42, the cylinder head 43, and the head cover 44 tilted forward greatly to a nearly horizontal state.

The unit case 30 of the power unit 3 extends from the internal combustion engine 4 to the rear left side and constitutes a transmission case part 31 that houses a belt-type continuously variable transmission. It is pivoted. As shown in FIG. 1, a rear cushion 16 is interposed between the rear end of the unit case 30 and the rear part of the main pipe 22.

A throttle body 52 connected to an intake pipe 51 extending from the entrance of an intake port 45 at the upper part of the cylinder head 42 of the internal combustion engine 4, and an air cleaner 53 connected to the throttle body 52 are disposed at the top of the power unit 3. has been done.
An exhaust pipe 55 connected to the outlet of the exhaust port 46 at the bottom of the cylinder head 42 is bent rearward, extends rearward along the right side of the vehicle, and is connected to a muffler 56 on the right side of the rear wheel 15. The muffler 56 is attached to the unit case 30 via a muffler stay 56a.

The front part 1F of the vehicle body is covered at the front and rear by a front cover 17a and a rear cover 17b, and the center part of the handle 12 is covered by a handle cover 17c.
A step plate 17d is stretched over the floor portion 1C, and lower side covers 17e extend downwardly along the left and right side edges of the step plate 17d.

The rear part 1R of the vehicle body is connected to the upper part of the rear part of the step plate 17d, and a body cover 17f is placed over the main pipe 22 from the front to the left and right sides, and the seat 11 covers the upper end opening of the body cover 17f so as to be openable and closable. It looks like this. The rear fender 18 extends obliquely downward from the rear portion of the body cover 17f that tapers upwardly and backwardly when viewed from the side, and covers the rear wheel 15 from above.

FIG. 2 is a right side view of the internal combustion engine 4 of the power unit 3 from the crankcase 40 to the head cover 44.
The internal combustion engine 4 of this embodiment is a forced air cooling type, and the right side of the crankcase 40 is covered with a fan cover 70, and the fan cover 70 has an opening for cooling air intake window 71 around the axis of the crankshaft 41. However, inside the cooling air intake window 71, a rotating fan (not shown) is provided concentrically with the crankshaft 41.
The cylinder block 42 and the cylinder head 43 are covered with a shroud 72 shown by a two-dot chain line, and the shroud 72 communicates with a fan cover 70. Cooling outside air is taken in from the cooling air intake window 71 by a rotating fan that rotates together with the crankshaft 41, and is forcibly fed into the shroud 72 via the fan cover 70, after cooling the cylinder block 42 and cylinder head 43. , is ejected.

Further, the internal combustion engine 4 of this embodiment employs an SOHC type valve system, and the driven sprocket 61a of the camshaft 61 of the valve train 60 provided in the cylinder head 43 and the driving sprocket 41a of the crankshaft 41 are connected to each other. A cam chain 62 as a transmission member that rotates the camshaft 61 by the rotation of the crankshaft 41 is installed between them, and a cam chain chamber 63 for this purpose is located inside the crankcase 40, cylinder block 42, and cylinder head 43. In this embodiment, it is provided in communication with the left part (see FIGS. 6 and 7).

The crankshaft 41 is driven to rotate clockwise in FIG. 2 by the back-and-forth movement of a piston (not shown) that slides inside a cylinder portion 42a (see FIG. 6) provided in the cylinder block 42 and oriented approximately in the front-back direction. It has become.
A camshaft 61 is rotatably supported in parallel to the crankshaft 41 at the front end of the cylinder head 43 and between the head cover 44 and the cylinder head 43 .

A combustion chamber 65 is formed between the cylinder head 43 and the front of a piston that moves back and forth (not shown) of the cylinder part 42a, and the part of the cylinder head 43 facing the cylinder part 42a constitutes a combustion chamber ceiling surface 65a. (See Figure 6).
The cylinder head 43 is provided with an intake valve and an exhaust valve (not shown) for controlling intake and exhaust air in the combustion chamber 65, and the intake valve and the exhaust valve are respectively provided on the camshaft 61 of the valve mechanism 60. The lift amount and opening/closing timing are respectively controlled by the cam surface as the camshaft 61 rotates.

That is, the valve mechanism 60 is interlocked with the crankshaft 41 by the transmission member 62, and due to the vertical movement of the piston, the rotational torque of the crankshaft 41, which is rotated clockwise in the illustration of FIG. 2, is applied to the cam chain. 62 to the camshaft 61, and the intake valve and the exhaust valve open at the combustion chamber ceiling surface 65a at a predetermined timing with respect to the combustion stroke of the internal combustion engine 4. , and an exhaust valve port 67 (see FIG. 6) of the exhaust port 46.

In order to properly open and close the intake valve and exhaust valve at predetermined timings, the tension of the cam chain 62 must be maintained at an appropriate level at all times.
However, vibrations may occur in the cam chain 62 due to sudden changes in the rotational speed of the crankshaft 41 due to sudden acceleration/deceleration by the driver or changes in running resistance from the road surface.

In this embodiment, as seen from the right side view shown in FIG. 2, the cam chain 62 travels while meshing with the driving sprocket 41a and the driven sprocket 61a due to the clockwise rotation of the driving sprocket 41a. The upper cam chain 62a on the side that is sent out to 61a is on the slack side, and the lower cam chain 62b on the side that is pulled by the drive sprocket 41a is on the tension side.

In order to prevent the above-mentioned vibration of the cam chain 62 and provide a constant tension, the internal combustion engine 4 is equipped with a mechanism that applies a predetermined pressure to the loose side of the cam chain 62, that is, the upper cam chain 62a, in order to maintain the tension of the cam chain 62. A cam chain tensioner mechanism 35 for pressing is provided, and the cylinder block 42 is provided with a tensioner slipper 36 for pressing and slidingly guiding the cam chain 62, and a screw tensioner 37 for pressing the tensioner slipper 36.

On the other hand, an oil pan 47 (see FIG. 8) is provided at the bottom of the crankcase 40.
Furthermore, an oil pump (not shown) that is driven by the power of the crankshaft 41 is provided inside the crankcase 40. When the oil pump is driven by the crankshaft 41, engine oil stored in the oil pan 47 is pumped. Oil (hereinafter simply referred to as "oil" in the claims) is sucked in through a strainer (not shown) and sent from the oil pump to various parts of the internal combustion engine 4 through a plurality of oil passages.
Note that the reference numeral 57 in FIG. 2 is an O2 sensor for exhaust gas.
Further, reference numeral 33 is a power unit side bracket for the upper link support structure of the power unit 3 described above.

Oil is supplied to the aforementioned valve mechanism 60 around the camshaft 61 in order to lubricate the bearings of the camshaft 61, the cams, and the like.
The present embodiment also includes a knock sensor 80 that senses knocking in the internal combustion engine 4 and outputs a detection signal thereof.
That is, when the knock sensor 80 detects vibrations caused by knocking occurring in the combustion chamber 65 of the internal combustion engine 4, the control unit (not shown) adjusts the ignition timing so that the ignition timing is delayed. The occurrence of knocking can be avoided.

Such control requires the knock sensor 80 to output an accurate detection signal in order to avoid the occurrence of knocking, and it is important to select a suitable mounting position for the knock sensor 80.
First, in order to detect knocking occurring in the combustion chamber 65, a position as close to the combustion chamber 65 as possible is preferable. However, there are overheating and positional restrictions around the combustion chamber ceiling surface 65a of the cylinder head 43, so it is conceivable to attach it to a wall surface surrounding the combustion chamber 65 near the cylinder head 43 of the cylinder block 42, for example.

Further, the knock sensor 80 itself needs to be prevented from increasing in temperature due to heat from the combustion chamber 65, and is required to be cooled as much as possible.
When the knock sensor 80 is arranged in an air-cooled internal combustion engine provided with the air-cooled fins 73 of this embodiment, the knock sensor 80 will be air-cooled on the surface of the internal combustion engine 4, and the knock sensor 80 will be placed far from the combustion chamber 65. However, the farther from the combustion chamber 65 the more difficult it becomes to detect knocking with high accuracy.
Therefore, in this embodiment, as will be described later, an oil cooling structure is provided for the knock sensor 80, and it is possible to provide the knock sensor 80 at a position closer to the combustion chamber 65.

Further, in the internal combustion engine 4 in which the cylinder block 42 and cylinder head 43 are installed with the cylinder block 42 and the cylinder head 43 tilted forward to a nearly horizontal state, the knock sensor 80 is usually installed at the lower side. If the exhaust side of the cylinder block 42 is selected, the knock sensor 80 may come into contact with the ground, and a guard or the like is required for this purpose.
If the intake side of the cylinder block 42, which is normally located on the upper side, is selected as the mounting location for the knock sensor 80, there will be restrictions on the degree of freedom in mounting the intake pipe 51, throttle body 52, air cleaner 53, etc. of the intake system and on the ease of assembly. There is a possibility that this may occur.

Further, when the side surface of the cylinder body 42 on the side where the cam chain chamber 63 is provided is selected as the mounting location of the knock sensor 80, the influence of vibration from the cam chain 62 and the like is taken into consideration.
Therefore, in this embodiment, as shown in FIGS. 1 and 2, a knock sensor 80 is attached to the side surface of the cylinder body 42 opposite to the side where the cam chain chamber 63 is provided, that is, the right side surface.
A harness 87 extends from the knock sensor 80 and is connected to a control unit (not shown) (see FIG. 2).

FIG. 3 is a right side view showing the cylinder block 42 of the internal combustion engine 4 shown in FIG. 2 taken out.
As shown in FIG. 3, a knock sensor 80 is attached to the right side wall 42d of the cylinder block 42 at a position that substantially overlaps the cylinder axis X when viewed from the right side.
FIG. 4 is a right side view of the cylinder block 42 shown in FIG. 3 with the knock sensor 80 removed.
In FIGS. 3 and 4, small black arrows schematically represent the flow of oil.
As shown in FIG. 4, a support part 81 is formed on the right side wall 42d of the cylinder block 42, and has a flat surface without air cooling fins 73 in order to attach the knock sensor 80. A sensor mounting hole 82 is drilled that does not penetrate through 42d, and a female thread 82a is formed at the back of the sensor mounting hole 82.

FIG. 5 is a schematic cross-sectional view of the attached state of the knock sensor 80 taken along the line VV in FIGS. 3 and 4. FIG.
The knock sensor 80 has a hollow hole 80a for mounting in the center, and a male thread 83a on the tip side of a mounting bolt 83 inserted through the hollow hole 80a is screwed into a female thread 82a of a sensor mounting hole 82 of the support part 81. Then, the knock sensor 80 is fastened and fixed to the cylinder block 42.

As shown in FIGS. 3 and 4, the mating surface 42c of the cylinder block 42 with respect to the crankcase 40 is provided with a crankcase mating surface supply oil passage 91C through which oil is supplied from an unillustrated oil pump in the crankcase 40. (See Figure 7).
The crankcase mating surface supply oil passage 91C is connected to an in-cylinder block supply oil passage 91 provided approximately in the cylinder axis X direction toward the cylinder head 43 at approximately the center of the right side wall 42d.

The cylinder block supply oil passage 91 includes a straight portion 91a (“cylinder block supply oil passage” in the present invention) approximately in the direction of the cylinder axis X, and a rear portion of the sensor mounting hole 82 (on the crankcase 40 side) in the support portion 81. It is provided with a semi-annular part ("cylinder block internal supply oil passage" in the present invention) 91b that goes around, and a straight part 91a is connected to the semi-annular part 91b at an oil inlet 91c at the lower part of the semi-annular part 91b.
Above, on the opposite side of the oil inlet 91c, the semi-annular portion 91b is an oil outlet 91d, and the cylinder head mating surface supply oil passage (in the present invention) provided on the mating surfaces 42b and 43b of the cylinder block 42 and the cylinder head 43. "Matching surface supply oil path") Connect to 91D.

Since the oil outlet 91d that discharges oil from the semi-annular part 91b is located at a higher position than the oil inlet 91c that supplies oil to the semi-annular part 91b, the cylinder block internal supply oil passage 91 in the support part 81 The structure allows oil bubbles to be easily discharged within the semi-annular portion 91b, thereby preventing oil bubbles from remaining in the semi-annular portion 91b, thereby effectively cooling the knock sensor 80. can do.

Most of the semi-annular part 91b of the cylinder block internal supply oil passage 91 in the support part 81 is shaped like a groove and is open to the surface of the support part 81. The knock sensor 80 is supported by the screwed mounting bolt 83, and the open surface is closed.
A gasket 84 made of paper, Bakelite, or the like having a lower thermal conductivity than the material of the cylinder block 42 and a gasket 84 made of stainless steel or the like are placed between the semi-annular portion 91b of the cylinder block supply oil passage 91 in the support portion 81 and the knock sensor 80. A washer 85 is inserted to close the open surface of the groove-shaped semi-annular portion 91b to form an oil passage.

As a result, the knock sensor 80 is attached to the supporting portion 81 facing the semi-annular portion 91b of the supply oil passage 91 in the cylinder block, and is attached to the semi-circular portion via the gasket 84 and washer 85 that close the open surface of the semi-annular portion 91b. Since it also comes into contact with the oil in the annular portion 91b, it contributes to cooling the knock sensor 80.
In addition, the gasket 84 and washer 85 suppress heat transfer from the metal surface of the support portion 81, which is the right side wall 42d of the cylinder block 42, to the knock sensor 80. 80 has a structure that makes it difficult for the temperature to rise.
Furthermore, after the oil passes through the semi-annular portion 91b, but before cooling the area around the combustion chamber 65 and the camshaft 61 as described later, the oil cools the knock sensor 80, making it possible to suppress the temperature rise. Therefore, the knock sensor 80 can be disposed close to the combustion chamber 65 to improve detection accuracy and cool the knock sensor 80.

Additionally, a washer 86 with low thermal conductivity is interposed between the knock sensor 80 and the head of the mounting bolt 83 to prevent direct contact between the knock sensor 80 and the mounting bolt 83. Transfer of heat from the cylinder block 42 to the knock sensor 80 via the mounting bolt 83 is suppressed.
Further, the cooling fins 73 on the right side wall 42d of the cylinder block 42 are not provided on the support portion 81, and are configured so that the heat of the cylinder block 42 is not transferred due to the cooling fins 73 coming into contact with the knock sensor 80. There is.

The semi-annular part 91b of the supply oil passage 91 in the cylinder block is connected at an oil outlet 91d to a cylinder head mating surface supply oil passage 91D provided on the right side of the mating surfaces 42b and 43b of the cylinder block 42 and the cylinder head 43. .
FIG. 6 is a front view of the cylinder block 42 taken along the line VI--VI in FIGS. 2, 3, and 4. The small black arrows in FIG. 6 schematically indicate the flow of oil.
As shown in FIG. 6, the cylinder head mating surface supply oil passage 91D reaches a connecting portion 92 located on the upper right side of the cylinder portion 42a of the mating surfaces 42b and 43b.

In this way, the oil discharged from the oil outlet 91d of the semi-annular portion 91b of the cylinder block internal supply oil passage 91 flows through the cylinder head mating surface supply oil passage 91D formed on the mating surface of the cylinder block 42 and the cylinder head 43. Since the oil passes between the combustion chamber 65 and the knock sensor 80, the structure cools the area around the combustion chamber 65 and prevents the heat of the combustion chamber 65 from being transmitted to the knock sensor 80. The cooling performance of the sensor 80 is improved.

The connecting portion 92 connects the inside of the cylinder head 43 to a first oil passage 91A (see FIG. 8) inside the cylinder head 43 that extends around the camshaft 61.
Note that the oil discharged from the oil outlet 91d is connected to the first oil passage 91A that supplies oil around the camshaft 61 in the upper part of the cylinder head 43 at the connection part 92, so that the oil in the oil is Air bubbles are discharged from the first oil passage 91A side.

Also, the reason why the connecting part 92 is located at the upper right of the cylinder part 42a is because the oil supply destination by the first oil passage 91A connected by the connecting part 92 is located at the upper part because the oil drips onto the camshaft 61 etc. This is to do so.

In this embodiment, the cylinder head mating surface supply oil passage 91D is shown in FIGS. It may be provided on the side mating surface 43b, or it may be provided on both mating surfaces 42b and 43b so as to be aligned so as to form a hole-shaped oil passage.

As shown in FIG. 6, a cylinder portion 42a is opened approximately in the center of a mating surface 42b of the cylinder block 42 with respect to the cylinder head 43, and a cylinder portion 42a is opened approximately in the center, and is arranged parallel to the cylinder axis X on a concentric circle Y around the cylinder axis X. Four through holes 48 are formed.
The cylinder head 43 connected to the mating surface 42b is also provided with four through holes 48 in parallel to the cylinder axis X at the same position, and the tips of stud bolts 49 inserted from the front of the cylinder head 43 are connected to the cylinder head. 43 and the through hole 48 of the cylinder block 42, and is screwed into the crankcase 40, and the cylinder head 43 and the cylinder block 42 are fastened and fixed to the crankcase 40.

The aforementioned cam chain chamber 63 opens on the left side of the cylinder portion 42a, and the screw tensioner 37 of the cam chain tensioner mechanism 35 is attached to the upper part of the cylinder block 42, facing the upper side of the cam chain chamber 63.
In FIG. 6, inside the cylinder part 42a, the position of the intake valve port 66 of the intake port 45 that opens to the combustion chamber ceiling part 65a of the cylinder head 43 attached to the cylinder block 42, and the position of the exhaust valve port 67 of the exhaust port 46 are shown. The position is indicated by an imaginary line (double-dashed line).

As shown in FIG. 6, the cylinder block internal supply oil passage 91 that opens to the mating surface 42b of the cylinder block 42 opens the oil outlet 91d of the semi-annular portion 91b to the right side of the cylinder portion 42a. The oil outlet 91d is connected to the cylinder head mating surface supply oil passage 91D of the mating surface 42b, and the cylinder head mating surface supply oil passage 91D extends upward on the mating surface 42b, and the cylinder head mating surface supply oil passage 91D is connected to the stud bolt 49 on the upper right side of the cylinder part 42a. It is connected to a connecting portion 92 provided on the mating surface 42b on the outside of the through hole 48.
In this way, the oil discharged from the oil outlet 91d passes through the cylinder head mating surface supply oil passage 91D formed on the mating surfaces 42b and 43b of the cylinder block 42 and the cylinder head 43, so that the oil discharged from the combustion chamber 65 and the knock Oil passes between the combustion chamber 65 and the sensor 80, which cools the surroundings of the combustion chamber 65 while making it difficult for heat to be transmitted to the knock sensor 80, improving the cooling performance of the knock sensor 80.

FIG. 7 is a rear view of the cylinder block 42 taken along arrow VII-VII in FIGS. 3 and 4. FIG. The small black arrows in FIG. 7 schematically indicate the flow of oil.
As shown in FIG. 7, the rear end of the straight portion 91a of the cylinder block supply oil passage 91, that is, the upstream end 91e, is connected to the crankcase provided on the right side of the mating surface 42c of the cylinder block 42 with the crankcase 40. Connect to mating surface supply oil path 91C.

The crankcase mating surface supply oil passage 91C has an oil supply part 93 at its lower end that connects to an oil passage 90 (see FIG. 8) from an oil pump (not shown) provided in the crankcase 40, and supplies oil from the oil pump. be supplied with.
Since the oil passage 90 that supplies oil by the oil pump from the oil pan 47 at the bottom of the crankcase 40 is located at the bottom, the oil supply part 93 is located at the bottom, and the oil supply part 93 is located at the bottom, and the oil supply part 93 is connected to the supply oil passage 91 in the cylinder block to supply oil to the crank mating surface. Oil line 91C is connected.
Although the crankcase mating surface supply oil passage 91C is shown as a groove-shaped one provided on the cylinder block 42 side, it may also be a groove-shaped one provided on the crankcase 40 side, and the two are formed together. It can be anything.

FIG. 8 is a right side sectional view of the internal combustion engine 4, taken along arrows VIII-VIII in FIG. The small black arrows in FIG. 8 schematically indicate the flow of oil.
Oil from the oil pan 47 is supplied to the crankcase mating surface supply oil passage 91C from an oil passage 90 from an oil pump (not shown) in the crankcase 40.
The oil in the crankcase mating surface supply oil passage 91C flows into the straight section 91a of the supply oil passage 91 in the cylinder block from its upstream end 91e, cools the knock sensor 80 in the semi-annular part 91b, and then is supplied to the cylinder head mating surface. It is connected to the first oil passage 91A at a connecting portion 92 via the oil passage 91D (see FIG. 6).
It is shown that the first oil passage 91A is disposed toward the front of the cylinder head 43 and toward the camshaft 61 of the valve mechanism 60.

Since the oil passage arrangement structure of the internal combustion engine of this embodiment is configured as described above, it has the following characteristics.
That is, a crankshaft 41 is rotatably supported by a crankcase 40, a cylinder block 42, a cylinder head 43, and a head cover 44 are connected to each other in an overlapping manner to the crankcase 40, and the cylinder block 42 is equipped with a knock sensor 80 that detects knocking. In the internal combustion engine 4,
The cylinder block 42 is provided with an internal cylinder block supply oil passage 91 (91a, 91b) through which oil is supplied from the crankcase 40 side.
The cylinder block 42 includes a support portion 81 on which the knock sensor 80 is attached facing the semi-annular portion 91b of the supply oil passage 91 in the cylinder block.

In this way, the knock sensor 80 is attached to the support part 81 facing the semi-annular part 91b of the cylinder block internal supply oil passage 91 provided in the cylinder block 42, so that the oil flows around the combustion chamber 65 and the camshaft 61. Before cooling the knock sensor 80, the oil cools the knock sensor 80, thereby suppressing the temperature rise. As a result, the knock sensor 80 can be disposed close to the combustion chamber 65 and the knock sensor 80 can be cooled while improving the knock detection function.
By controlling the ignition timing through highly accurate knocking detection, it is possible to optimize combustion in the combustion chamber 65, which in turn contributes to mitigating or reducing the impact of climate change by reducing emissions of harmful substances.

The cylinder block supply oil passage 91 in the support part 81, that is, the oil inlet 91c through which oil is supplied to the semi-annular part 91b is located below the oil outlet 91d through which oil is discharged from the semi-annular part 91b in the support part 81. Since the oil outlet 91d is located at a higher position than the oil inlet 91c, it is possible to create a structure in which oil bubbles in the semi-annular part 91b of the support part 81 can be easily discharged. Since oil bubbles are prevented from remaining in the annular portion 91b, the knock sensor 80 can be effectively cooled.

The oil outlet 91d is connected to a cylinder head mating surface supply oil passage 91D formed on the mating surfaces 42b and 43b of the cylinder block 42 and the cylinder head 43, and the oil discharged from the oil outlet 91d is connected to the cylinder head mating surface 42b, 43b. Since the oil passes through the surface supply oil passage 91D, the oil passes between the combustion chamber 65 and the knock sensor 80, and the structure is such that heat is not easily transmitted to the knock sensor 80 while cooling the area around the combustion chamber 65. Therefore, the cooling performance of the knock sensor 80 is improved.

A gasket 84 having a lower thermal conductivity than the cylinder block 42 is interposed between the semi-annular portion 91b of the cylinder block supply oil passage 91 in the support portion 81 and the knock sensor 80.
Therefore, the knock sensor 80 is insulated from the cylinder block 42 by the gasket 84, which has low thermal conductivity, so the knock sensor 80 has a structure in which the temperature does not easily rise, and the knock sensor 80 is cooled by the wind from outside the internal combustion engine 4. This improves the cooling performance of the knock sensor 80.

Although one embodiment of the present invention has been described above, the aspects of the present invention are not limited thereto, and may include various aspects within the gist of each claim. For example, the mounted vehicle is not limited to the scooter-type motorcycle shown in the embodiment, and the internal combustion engine is not limited to the one provided in the swing-type power unit of the embodiment, but is an internal combustion engine fixed on the body frame. For convenience of explanation, the left and right front and rear directions have been described according to what is shown in the drawings, but for example, the left and right positions may be reversed.

DESCRIPTION OF SYMBOLS 1...Motorcycle, 2...Body frame, 3...Power unit (swing type power unit), 4...Internal combustion engine, 30...Unit case, 31...Transmission case part, 32...Reduction mechanism, 35...Cam chain tensioner mechanism, 36...Tensioner Slipper, 37...Screw tensioner, 40...Crank case, 41...Crankshaft, 41a...Drive sprocket, 42...Cylinder block, 42a...Cylinder part, 42b...Matching surface, 42c...Matching surface, 42d...Right side wall, 43... Cylinder head, 43b...mating surface, 45...intake port, 46...exhaust port, 47...oil pan, 48...through hole, 49...stud bolt, 60...valve mechanism, 61...camshaft, 61a...driven sprocket, 62 ...Cam chain ("transmission member" in the present invention), 63...Cam chain chamber, 65...Combustion chamber, 65a...Ceiling surface of combustion chamber, 66...Intake valve port, 67...Exhaust valve port, 73...Air cooling fin, 80... Knock sensor, 80a...Hollow hole, 81...Support, 82...Sensor mounting hole, 82a...Female thread, 83...Mounting bolt, 83a...Male thread, 84...Gasket, 85...Washer, 86...Washer, 87...Harness, 90... Oil passage, 91... Cylinder block supply oil passage, 91a... Straight section ("cylinder block supply oil passage" in the present invention), 91b... Semi-annular part ("cylinder block supply oil passage" in the present invention), 91c ...Oil inlet, 91d...Oil outlet, 91e...Upstream end, 91A...First oil passage, 91C...Crankcase mating surface supply oil passage, 91D...Cylinder head mating surface supply oil passage ("mating surface supply oil passage in the present invention") ), 92...Connection part, 93...Oil supply part, X...Cylinder axis, Y...Concentric circle

Claims (4)

a crankcase (40) in which a crankshaft (41) is rotatably supported;
a cylinder block (42) connected to the crankcase (40) and forming a cylinder portion (42a);
a cylinder head (43) connected to the cylinder block (42) and having an intake port (45) and an exhaust port (46);
An internal combustion engine (4) including a knock sensor (80) provided in the cylinder block (42) to detect knocking,
The cylinder block (42) is provided with an internal cylinder block supply oil passage (91, 91a, 91b) through which oil is supplied from the crankcase (40) side,
An internal combustion engine characterized in that the cylinder block (42) is provided with a support part (81) on which at least a part of the knock sensor (80) is attached facing the supply oil passage (91b) in the cylinder block. Oil passage arrangement structure. An oil inlet (91c) through which oil is supplied to the cylinder block internal supply oil passage (91b) in the support part (81) is an oil inlet (91c) through which oil is supplied from the cylinder block internal supply oil passage (91b) in the support part (81). The oil passage arrangement structure for an internal combustion engine according to claim 1, wherein the oil passage arrangement structure for an internal combustion engine is located below an oil outlet (91d) from which the oil is discharged. The oil outlet (91d) is connected to a mating surface supply oil passage (91D) formed on the mating surfaces (42b, 43b) of the cylinder block (42) and the cylinder head (43), and The oil passage arrangement structure for an internal combustion engine according to claim 2, wherein the oil discharged from the mating surface supply oil passage (91D) passes through the mating surface supply oil passage (91D). A gasket (84) having a lower thermal conductivity than the cylinder block (42) is interposed between the cylinder block internal supply oil passage (91b) and the knock sensor (80) in the support portion (81). The oil passage arrangement structure for an internal combustion engine according to claim 1, characterized in that:

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