JP6632734B2 - Lubrication structure of internal combustion engine - Google Patents

Description

  The present invention relates to a lubricating structure in an internal combustion engine, in particular, including a centrifugal oil filter.

  2. Description of the Related Art In a lubricating structure of an internal combustion engine, an example in which a centrifugal oil filter that centrifugally separates and filters oil using the rotation of an engine is provided, particularly during supply of oil to a lubricating portion around a crankshaft (for example, Patent Document 1) 1).

JP 2014-70568 A

  The lubricating structure disclosed in Patent Literature 1 drives an oil pump provided in a crankcase cover to draw oil stored in an oil pan through a drawing channel and discharge the oil into a discharging channel formed in the crankcase cover. Since the discharge passage communicates with the shaft end oil supply chamber that also supports the shaft end of the crank shaft formed on the crankcase cover, the discharged oil reaches the shaft end oil supply chamber.

In the crankshaft, an upstream main flow path and a downstream main flow path drilled from the shaft end are formed in the shaft center of the shaft part apart from each other, and the upstream main flow path and the downstream main flow path of the shaft part are formed. A centrifugal oil filter is provided at a position between the two, and the inside of the disc-shaped centrifugal oil filter communicates with the upstream main flow path and also communicates with the downstream main flow path.
Therefore, when the oil discharged by the driving of the oil pump reaches the shaft end oil supply chamber, it enters the upstream main flow path from the shaft end oil supply chamber, and is further guided into the communicating centrifugal oil filter.

When the centrifugal oil filter rotates integrally with the crankshaft, foreign matter with a high specific gravity mixed in the oil moves to the outer periphery due to centrifugal force and is separated, and the filtered oil communicates downstream from the centrifugal oil filter. Flows out to the side main flow path.
The oil that has entered the downstream main flow path is discharged to the outer peripheral surface of the crankpin and the like by the branched sub flow path, and is supplied to the shaft supporting portion with the large end of the connecting rod.

As described above, in the lubrication structure disclosed in Patent Literature 1, one centrifugal oil filter is provided as an oil filter for filtering oil in the oil passage to the lubrication portion of the crankshaft downstream of the oil pump. Have been.
An oil strainer is generally provided upstream of the oil pump when drawing oil stored in the oil pan.

However, the oil strainer removes relatively large foreign matter, and fine foreign matter having a large specific gravity, such as metal powder that damages a bearing portion to be lubricated, needs to be separately removed by an oil filter. , A centrifugal oil filter removes fine foreign matter.
The centrifugal oil filter has a flat disk shape, and foreign substances such as sludge and metal powder having a high specific gravity mixed in the oil move radially outward by rotation and accumulate on the inner peripheral portion of the disk.

The centrifugal oil filter is installed on the shaft of the crankshaft, so there is not enough space to arrange it because it is necessary to avoid interference with other equipment. I do, but there are limitations.
Therefore, the frequency of maintenance for performing a cleaning operation for removing deposits accumulated inside the centrifugal oil filter increases.

At the time of the maintenance, the centrifugal oil filter is provided on the shaft of the crankshaft, so it is necessary to remove the crankcase cover, which requires a large amount of maintenance and has accumulated inside the centrifugal oil filter. Since a cleaning operation for removing foreign substances and the like must be performed, labor is required.
Performing such maintenance work frequently is extremely troublesome and costly.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to secure a sufficient oil capacity of an oil filter, to reduce the frequency of maintenance, and to perform maintenance of a centrifugal oil filter by simple maintenance work. Another object of the present invention is to provide a lubricating structure for an internal combustion engine that can reduce labor by reducing the frequency of the operation.

In order to achieve the above object, a lubricating structure for an internal combustion engine according to the present invention includes:
An engine case is configured by a crankcase that rotatably supports the crankshaft, and a pair of crankcase covers that respectively cover the crankcase from both sides in a direction in which the crankshaft is directed,
An oil reservoir is provided on the bottom wall of the crankcase,
In a lubricating structure for an internal combustion engine in which a centrifugal oil filter is provided on a shaft portion of the crankshaft protruding laterally from the crankcase,
An oil filter having a built-in filter element is provided in an oil passage extending from an oil pump for pumping oil from the oil reservoir to the centrifugal oil filter.

  According to this configuration, in the lubrication structure of the internal combustion engine in which the centrifugal oil filter is provided on the shaft portion of the crankshaft that protrudes laterally from the crankcase, the centrifugal oil is pumped from the oil reservoir to the centrifugal oil. Since the oil filter including the filter element is provided in the oil passage leading to the filter, the overall oil capacity of the oil filter is significantly increased, and the frequency of maintenance can be suppressed.

  The oil filter with a built-in filter element replaces the filter element rather than the centrifugal oil filter, which is cleaned for maintenance. Maintenance is easier, and simple maintenance of the oil filter is troublesome. Maintenance of such a centrifugal filter is extremely infrequent and labor can be greatly reduced.

In the above configuration,
The oil filter may be provided on an outer wall of the engine case.

  According to this configuration, since the oil filter is provided on the outer wall of the engine case, there is no cover member that covers the oil filter from the outside, and the oil filter is more easily and quickly reduced without having to remove the cover member. Filter maintenance can be performed.

In the above configuration,
The oil filter may be provided at a position where the oil filter does not overlap with the centrifugal oil filter when viewed in the axial direction of the crankshaft.

  According to this configuration, the oil filter is disposed at a position that does not overlap with the centrifugal oil filter when viewed in the axial direction of the crankshaft. The size can be reduced.

In the above configuration,
The oil filter may be provided on an outer peripheral wall extending in the axial direction from a peripheral edge of a side wall of the engine case substantially perpendicular to the axial direction of the crankshaft.

According to this configuration, the engine case includes the side wall that is substantially perpendicular to the axial direction of the crankshaft and the outer peripheral wall that extends in the axial direction from the peripheral edge of the side wall. By providing the oil filter, the oil filter is firmly provided and the strength and rigidity of the outer peripheral wall can be further improved.
Further, the oil filter can be provided without increasing the width of the crankshaft of the internal combustion engine in the axial direction, and the size of the internal combustion engine can be avoided.

In the above configuration,
A part of the oil filter may be provided to protrude outside the outer peripheral wall when viewed in the axial direction of the crankshaft.

  According to this configuration, the oil filter is provided so as to partially protrude outside the outer peripheral wall when viewed in the axial direction of the crankshaft. Intrusion of the filter into the outer peripheral wall can be reduced, and interference with the internal structure can be avoided.

In the above configuration,
The internal combustion engine is provided with a cylinder block protruding from the crankcase so that a cylinder axis is substantially horizontal,
The oil filter may be provided on a corner wall portion of the outer peripheral wall of the engine case from a wall portion where the cylinder block projects to a bottom wall portion.

  According to this configuration, the internal combustion engine is provided with the cylinder block protruding from the crankcase so that the cylinder axis is substantially horizontal, and the outer peripheral wall of the engine case extends from the wall where the cylinder block protrudes to the bottom wall. Since the oil filter is provided on the corner wall portion, the oil filter can be provided by utilizing a dead space near or below the engine case below or near the cylinder block.

In the above configuration,
The oil filter may be positioned above a lower surface of the bottom wall.

  According to this configuration, since the oil filter is located above the lower surface of the bottom wall of the engine case, the oil filter does not protrude below the lower surface of the bottom wall of the engine case, and the oil filter does not protrude from the ground of the internal combustion engine. The required distance can be easily secured.

In the above configuration,
The oil filter may be arranged below the oil pump.

  According to this configuration, since the oil filter is disposed below the oil pump, when the internal combustion engine stops operating, the oil filter disposed below the stopped oil pump is filled with oil. In this case, the oil can be circulated without delay at the time of restart.

In the above configuration,
An oil drain hole communicating with the oil storage portion is formed in the bottom wall of the crankcase so as to open downward,
The opening of the oil drain hole is closed by a cap,
An oil strainer held by the cap is arranged in the oil drain hole,
The upstream side of the oil strainer is communicated with the oil reservoir,
The downstream side of the oil strainer may be communicated with a pumping oil passage for pumping oil by the oil pump.

  According to this configuration, the oil drain hole provided in the bottom wall portion of the crankcase is closed by the cap, the oil strainer held by the cap is arranged in the oil drain hole, and the upstream side of the oil strainer communicates with the oil reservoir. Since the downstream side of the oil strainer is communicated with an oil pumping oil passage for pumping oil by an oil pump, relatively large foreign matters are removed by the oil strainer from the oil stored in the oil storage unit, and the oil is pumped up by the oil pump. The oil discharged from the pump passes through an oil filter to remove fine foreign matter, and then flows into a centrifugal oil filter, where finer foreign matter is further removed and supplied to a lubricating portion of a crankshaft.

Since relatively large foreign matter is removed by the oil strainer on the upstream side of the oil filter, the load on the oil filter is reduced and deterioration is suppressed.
In addition, since the oil strainer held by the cap is arranged in the oil drain hole, by removing the cap from the oil drain hole, the oil strainer can be taken out from the inside of the crankcase, and maintenance of the oil strainer can be simplified. .

  The present invention relates to a lubrication structure for an internal combustion engine in which a centrifugal oil filter is provided on a shaft part of a crankshaft of a crankshaft protruding laterally, wherein an oil pump that pumps up oil from an oil reservoir to a centrifugal oil filter. Since an oil filter using a filter element is provided in the oil passage leading to the oil passage, the overall oil capacity of the oil filter is significantly increased, and the frequency of maintenance can be suppressed.

  The maintenance of the oil filter, which has a built-in filter element, is easier than the centrifugal oil filter that requires cleaning, so maintenance is simpler. Maintenance of such a centrifugal filter is extremely infrequent and labor can be greatly reduced.

1 is a side view of a motorcycle equipped with an internal combustion engine including a centrifugal clutch according to a first embodiment of the present invention. FIG. 2 is a side view mainly showing an engine case of the internal combustion engine of the motorcycle. FIG. 2 is a bottom view of the vicinity of the internal combustion engine of the motorcycle. FIG. 10 is a sectional view of the internal combustion engine (a sectional view taken along line IV-IV in FIG. 9). FIG. 5 is a partially enlarged sectional view of FIG. 4. FIG. 10 is a sectional view of the internal combustion engine (a sectional view taken along line VI-VI in FIG. 9). FIG. 3 is a side view of the internal combustion engine with a right crankcase cover removed. FIG. 8 is a side view of the internal combustion engine with the right crankcase cover, the centrifugal clutch, and the like removed from the state of FIG. 7. It is sectional drawing of the same internal combustion engine cut | disconnected perpendicularly to the axial direction of the crankshaft at the right crankcase. It is a perspective view of a right crankcase cover. FIG. 2 is a perspective view of the circulation path of oil in the internal combustion engine. FIG. 8 is a side view of the internal combustion engine according to the second embodiment with the right crankcase cover removed. FIG. 11 is a side view of the internal combustion engine according to a third embodiment with a right crankcase cover removed.

Hereinafter, a first embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view of a motorcycle 1 on which an internal combustion engine E equipped with a centrifugal oil filter 75 is mounted.
In the description of the present specification, the front, rear, left, and right directions are based on a normal reference that the forward direction of the motorcycle 1 according to the present embodiment is forward, and in the drawings, FR indicates forward and RR indicates backward. , LH indicate the left side, and RH indicates the right side.

  One main frame 3 extends obliquely downward and backward from the head pipe 2, and a pair of left and right pivot plates 4, 4 is vertically provided downward at the rear end of the main frame 3. A pair of left and right rear frames 5 and 5 extend diagonally upward and rearward, and sub-frames 6 and 6 are provided between the main frame 3 and the rear frames 5 and 5.

A bar handle 7h is attached to an upper end of a steering shaft 7 pivotally supported by the head pipe 2, a lower portion of the steering shaft 7 is connected to a front fork 7f, and a front wheel 9 is pivotally supported at a tip of the front fork 7f. .
A swing arm 11 is pivotally supported by a pivot shaft 10 at a front end thereof and is vertically swingably connected to the pivot plate 4. A rear wheel 12 is pivotally supported at a rear end of the swing arm 11.
A rear cushion 13 is interposed between the swing arm 11 and the upper rear frame 5.

An internal combustion engine E is suspended by being supported by an engine hanger 3 h and a pivot plate 4 projecting downward from a rear portion of the center of the main frame 3.
The internal combustion engine E is a four-stroke cycle, one cylinder air-cooled internal combustion engine, and is mounted on a vehicle body frame in a horizontal posture in which the crankshaft 40 is directed in the left-right vehicle width direction.

  The internal combustion engine E includes a pair of left and right split crankcases 21L and 21R that rotatably support the crankshaft 40, and a pair of left crankcases that cover the left and right crankcases 21L and 21R from left and right sides. The engine case 20 is composed of the cover 22L and the right crankcase cover 22R.

A cylinder block 23, a cylinder head 24, and a cylinder head cover 25 are sequentially stacked and protruded forward from the left and right crankcases 21L and 21R of the engine case 20.
The cylinder axis Lc, which is the center axis of the cylinder of the cylinder block 23, is tilted forward to near horizontal and the cylinder block 23 projects, and a cylinder head 24 and a cylinder head cover 25 are sequentially stacked in front of the cylinder block 23.

An intake pipe 30 extends upward from the upper surface of the cylinder head 24 which is arranged to project substantially horizontally forward, and the intake pipe 30 is connected to an air cleaner 32 attached to the main frame 3 via a throttle body 31. .
Referring to FIGS. 1 and 3, an exhaust pipe 35 extending downward from the lower surface of the cylinder head 24 is bent to extend rearward along the lower surface of the internal combustion engine E, and to the rear of the engine case 20 and to the right of the vehicle body. It is connected to the arranged muffler 38.

In the middle of the exhaust pipe 35, two catalytic converters, a first catalytic converter 36 and a second catalytic converter 37, are sequentially arranged.
The first catalytic converter 36 on the upstream side near the cylinder head 24 is disposed substantially horizontally and obliquely in the front-rear direction below the cylinder block 23 inclined forward to near the horizontal (see FIGS. 1 and 3). The downstream second catalytic converter 37 is disposed inside the muffler 38 (see FIG. 1).
The first catalytic converter 36 and the second catalytic converter 37 are both three-way catalysts.

By having the catalyst divided into two parts, the first catalytic converter 36 and the second catalytic converter 37, the same capacity as the large catalytic converter is secured and the purification performance is improved. The first catalytic converter 36 is disposed compactly below the cylinder block 23, and the other second catalytic converter 37 can be accommodated in the muffler 38.
Since the first catalytic converter 36 is disposed on the upstream side of the exhaust gas and below the cylinder block 23, the catalyst is quickly heated and activated when the engine is started, so that the exhaust gas can be purified from an early stage of the start.
Referring to FIG. 3, an exhaust pipe 35 downstream of the first catalytic converter 36 passes closely between the right crankcase 21R and the filter housing (121) of the oil filter 120.
Therefore, the first catalytic converter 36 can be arranged close to the crankcase 21.

As shown in FIG. 1, a front cover 14 covers the front of the head pipe 2 of the vehicle body frame, and the right and left sides of the main frame 3 from above the main frame 3 are the left and right sides of the cylinder block 23, the cylinder head 24, and the cylinder head cover 25. The leg shield 15 covers the side, and the body cover 16 covers the rear part of the main frame 3 and the left and right sides of the rear frame 5.
A seat 18 and a loading platform 19 are provided on the front and back of the upper part of the body cover 16, and the opening between the seat 18 on the front upper side of the body cover 16 is closed by the center cover 17.

The engine case 20 of the internal combustion engine E is not covered by the leg shield 15 and the body cover 16 and is exposed on the side (see FIG. 1).
On the right side of the front part of the engine case 20, a tip part bent upward above a brake pedal 28 extending forward from below the engine case 20 from below the pivot plate 4 is swingably positioned.
A step 29 is located on the side of the front and rear central portion of the engine case 20.
A kick starter pedal 27 extending obliquely rearward and upward is located on the rear right side of the engine case 20.

FIG. 4 is a cross-sectional development view (cross-sectional view taken along the line IV-IV in FIG. 9) of the internal combustion engine E. Referring to FIG. 4, the crankshaft 40 of the internal combustion engine E is installed in the left and right crankcases 21L and 21R. A left shaft portion 40L and a right shaft portion 40R project coaxially and integrally from a pair of left and right crank webs 40w, 40w to be accommodated, respectively, and a crank pin 40p is connected between the left and right crank webs 40w, 40w to form a crank-shaped integrated structure. belongs to.
The crankshaft 40 is rotatably supported by the left and right crankshafts 40L, 40R of the left shaft portion 40L and the right shaft portion 40R, respectively, being rotatably supported by the left and right crankcases 21L, 21R via a pair of left and right main bearings 41, 41. You.

The piston pin 42p of the piston 42 slidably fitted in the cylinder bore of the cylinder block 23 and the crankpin 40p of the crankshaft 40 are connected by a connecting rod 43, and the reciprocating motion of the piston 42 The rotation is converted into rotation of the shaft 40.
In the combustion chamber 24a formed between the top surface of the piston 42 and the ceiling surface of the cylinder head 24, a spark plug 44 fitted into the ceiling wall of the cylinder head 24 faces the electrode at the tip.

  A drive sprocket 45, a starter driven gear 46, and an AC generator 48 are sequentially provided on the left shaft portion 40L extending leftward from the left main bearing 41 of the crankshaft 40 from the main bearing 41 side to the left.

  Between a driving sprocket 45 integrally connected to the left shaft portion 40L of the crankshaft 40 and a cam sprocket 151 integrally fitted to a valve system cam shaft 150 rotatably supported by the cylinder head 24. Is an intake rocker arm that swings around the timing chain 152, rotates the camshaft 150 at half the rotation speed of the crankshaft 40, and swings in contact with the intake cam 150i and the exhaust cam 150e of the camshaft 150, respectively. The intake and exhaust valves 153i and the exhaust rocker arm 153e open and close an intake valve and an exhaust valve (not shown) at a predetermined timing to perform intake and exhaust of the internal combustion engine E.

In the AC generator 48, the outer rotor 48r is fitted to the left end of the left shaft portion 40L of the crankshaft 40, and the inner stator 48s is fixedly supported by the left crankcase cover 22L.
A starter driven gear 46 rotatably supported on the left shaft portion 40L via a needle bearing 49 is provided with a one-way clutch 47 between the starter driven gear 46 and an outer rotor 48r of an AC generator 48 integrally connected to the crankshaft 40. Only one-way power is transmitted from the starter driven gear 46 to the outer rotor 48r and the crankshaft 40, and the internal combustion engine E can be started.

On the other hand, a centrifugal clutch 70 and a centrifugal oil filter 75 are provided on the right shaft portion 40R extending rightward from the right main bearing 41 of the crankshaft 40.
Referring to FIG. 4, a pump drive gear 51 is fitted to the right shaft portion 40R of the crankshaft 40 in contact with the inner race of the main bearing 41 from the right side. The primary drive gear 53 is further rotatably fitted to the right shaft portion 40R in contact with the thrust bearing 52 from the right side.

Then, the outer cylindrical member 54 is in contact with the cylindrical base portion of the primary drive gear 53 from the right side and is rotatably fitted to the right shaft portion 40R.
As shown in FIG. 5, the outer cylinder member 54 has a flange portion 54 b which is developed in the outer peripheral direction at the right end of a cylindrical portion 54 a having the same diameter which is in contact with the cylindrical base portion of the primary drive gear 53, and is provided on the right side of the flange portion 54 b. A right end cylindrical portion 54c having a larger diameter than the cylindrical portion 54a protrudes from the surface.

Referring to FIG. 5, the right shaft portion 40R of the crankshaft 40 is formed with a spline shaft portion 40Ra in which a spline is formed by reducing the diameter of the right shaft portion 40a of the outer cylinder member 54 to the right through a step portion through a step portion. The shaft end 40Rb is further to the right of the spline shaft 40Ra.
The washer 55 is fitted to the spline shaft portion 40Ra inside the right end cylindrical portion 54c of the outer cylindrical member 54, and the annular member 56 is spline-fitted after coming into contact with the step portion.
A needle bearing 57 is interposed between the outer peripheral surface of the annular member 56 and the inner peripheral surface of the right end cylindrical portion 54c of the outer cylinder member 54.

An annular boss member 61 for supporting the drive plate 60 is further spline-fitted to the spline shaft portion 40Ra of the crankshaft 40.
Then, an annular oil passage forming fitting 62 is fitted to the shaft end 40Rb on the right side of the spline shaft 40Ra to abut against the annular boss member 61, and the nut member 64 is further connected to the shaft end 40Rb via the washer 63. By screwing and tightening, the annular member 56 and the annular boss member 61 are integrally fixed to the right shaft portion 40R of the crankshaft 40.
Therefore, the drive plate 60 supported by the annular boss member 61 rotates integrally with the crankshaft 40.

The drive plate 60 is composed of a bowl-shaped outer peripheral portion 60a fitted to the annular boss member 61 and a flange portion 60b extending outward from the open end of the bowl-shaped outer peripheral portion 60a. , And the flange portion 60b faces the flange portion 54b of the outer tubular member 54.
A centrifugal clutch 70 is formed between the drive plate 60 that rotates integrally with the crankshaft 40 and the bowl-shaped clutch outer 71 that is fixed to the flange portion 54b of the outer cylinder member 54.

  On the three support shafts 72 fixed to the drive plate 60, clutch shoes 73 each composed of three centrifugal weights are supported swingably, and each clutch shoe 73 having a lining made of a friction material on the outer surface is When the crankshaft 40 rotates with the rotation of the crankshaft 40 and swings radially outward against the clutch spring 74 due to centrifugal force, and when a predetermined number of rotations is exceeded, the clutch shoe 73 contacts the clutch outer 71 and the centrifugal clutch 70 is connected, and the rotation of the crankshaft 40 is transmitted to the outer cylinder member 54.

  The drive plate 60 is covered with a cover plate 76 from the right side so as to cover the opening of the bowl-shaped outer peripheral portion 60a that covers the outer periphery of the nut member 64, thereby forming an annular space 75s therein. 75 can be configured.

  The cover plate 76 is a disk-shaped member having a circular hole into which the shaft end portion 40Rb of the crankshaft 40 is fitted at the center, and the outer peripheral portion of the cover plate 76 fitted to the shaft end portion 40Rb is a flange portion of the drive plate 60. 60b is applied with an annular seal member 77 interposed therebetween, and a plurality of bolts 78 are threaded circumferentially through the outer peripheral portion of the cover plate 76 and the annular seal member 77 into the flange portion 60b of the drive plate 60. By tightening, the cover plate 76 is attached to the drive plate 60 to form a centrifugal oil filter 75 having an annular space 75s inside.

Referring to FIGS. 4 and 5, a short first shaft oil passage 40 </ b> A is formed in the right shaft portion 40 </ b> R of the crankshaft 40 at the shaft end portion 40 </ b> Rb from the shaft end surface to the center of the shaft. A long second shaft oil passage 40B is formed from the center of the shaft to a position short of the first shaft oil passage 40A.
The opening of the second axial oil passage 40B is closed by a plug member 79.

Referring to FIG. 5, a nut member 64 is screwed into a portion of shaft end 40Rb that separates first oil passage 40A and second oil passage 40B.
A branch oil passage 40Aa radially branched from the first axial oil passage 40A is formed between the nut member 64 and the cover plate 76, and the branch oil passage 40Aa opens to the annular space 75s.

On the other hand, in the annular boss member 61 that supports the drive plate 60, a lead-out oil passage 61a cut out to the outer peripheral surface of the spline shaft portion 40Ra is formed between the annular boss member 61 and the oil passage forming bracket 62.
The second in-shaft oil passage 40B is formed so that a branch oil passage 40Ba radially branched at the right end thereof communicates with the lead-out oil passage 61a (see FIG. 5).

Therefore, the first shaft oil passage 40A communicates with the second shaft oil passage 40B through the branch oil passage 40Aa, the annular space 75s of the centrifugal oil filter 75, the lead-out oil passage 61a, and the branch oil passage 40Ba in this order. I have.
When the centrifugal oil filter 75 rotates with the rotation of the crankshaft 40, the oil entering the annular space 75s from the first shaft oil passage 40A moves to the outer periphery due to the centrifugal force of the foreign matter having a high specific gravity mixed in the oil. The separated and filtered oil enters the second axial oil passage 40B from the outlet oil passage 61a.

Referring to FIG. 4, a second oil passage 40 </ b> B in the right shaft portion 40 </ b> R of the crankshaft 40 has a branch oil passage 40 </ b> Bb branching radially toward the inner peripheral surface of the outer cylinder member 54. The oil filtered by the centrifugal oil filter 75 is supplied to the lubricating portion where the branch oil passage 40Bc branches toward the inner peripheral surface of the primary drive gear 53 and rotates relatively.
Further, in the second in-shaft oil passage 40B, a branch oil passage 40Bd is branched from around the crank web 40w toward the crankpin 40p, and the branch oil passage 40Bd communicates with the oil passage 40pa in the crankpin 40p. The filtered oil is supplied from the passage 40pa to a lubricating portion such as a shaft support portion between the crankpin 40p and the connecting rod 43.

As shown in FIG. 9, the internal combustion engine E includes a continuously variable gear-type multi-stage transmission 80 at the rear of the crankshaft 40, and a main shaft 81 and a counter shaft 82 of the multi-stage transmission 80 are arranged side by side. It is rotatably supported by the crankcases 21L and 21R.
In the left and right crankcases 21L and 21R, a main gear group 81G on the main shaft 81 and a counter gear group 82G on the counter shaft 82 mesh with each other corresponding gears.

Referring to FIG. 4, main shaft 81 of multi-stage transmission 80 is provided with transmission clutch 85 at a portion protruding rightward through right crankcase 21R and projecting therefrom.
A primary driven gear 84 rotatably supported by the main shaft 81 supports a clutch outer 86 of a transmission clutch 85 via a damper. A primary driven gear 84 supporting the clutch outer 86 is supported by the crankshaft 40. The primary drive gear 53 is engaged with the primary drive gear 53.

  The speed change clutch 85 is a friction type multi-plate clutch having a number of clutch plates that are frictionally joined or released by a release mechanism operated by a driver. When the torque of the outer 86 is transmitted to the clutch inner 87 that is integrally connected to the main shaft 81, the transmission clutch 85 is connected, and when the frictional joining of many clutch plates is released, the clutch inner 86 Transmission of torque to 87 is interrupted, and shift clutch 85 is disengaged.

The countershaft 82 of the multi-stage transmission 80 is an output shaft, and a drive sprocket 88 is fitted to the left end that penetrates the left crankcase 21L to the left.
The drive chain 89 wound around the drive sprocket 88 is wound around the other driven sprocket (not shown) on the rear wheel 12 side, and the driving force of the internal combustion engine E is transmitted to the rear wheel 12 via the drive chain 89. The motorcycle 1 runs.

  A shift drum 90 is rotatably supported by the left and right crankcases 21L and 21R, obliquely above the front and rear main shafts 81 and the counter shaft 82, which are supported by the left and right crankcases 21L and 21R in parallel with each other. 9 and 6).

  As shown in FIG. 6, the shift drum 90 has circumferentially formed lead grooves 90Aa and 90Ab for moving the shift forks 91 and 92 in the axial direction on the outer peripheral surface of the cylindrical main body 90A. A left end shaft portion 90L, which has a reduced outer diameter to the left from 90A and protrudes, is rotatably fitted into a bearing hole of the left crankcase 21L and is journalled, while a flange portion is provided at the right end of the cylindrical main body portion 90A. A right end shaft portion 90R, which has an outer diameter reduced to the right from the flange portion 90f and protrudes, is rotatably supported via a needle bearing 93 in a bearing hole of the right crankcase 21R. I have.

The bearing hole of the left crankcase 21L, which supports the left end shaft portion 90L of the shift drum 90, substantially bears the lower half, and the upper half becomes hollow so that oil can be stored.
Therefore, the right end shaft portion 90R of the shift drum 90 is supported by the needle bearing 93 interposed while securing the width of the bearing hole of the right crankcase 21R, thereby preventing the shift drum 90 from tilting and shifting. The drum 90 rotates smoothly without resistance.

As described above, the crankshaft 40, the main shaft 81, the counter shaft 82, and the shift drum 90 are rotatably supported by the left and right crankcases 21L and 21R. The centrifugal clutch 70 and the centrifugal oil filter 75 provided on the right shaft 40R projecting right from the right crankcase 21R of 40, and the right shaft protruding right from the right crankcase 21R of the main shaft 81 are provided. The transmission clutch 85 is provided (see FIG. 4).
As shown in FIG. 4, the centrifugal clutch 70, the centrifugal separation type oil filter 75, and the speed change clutch 85 are covered by a right crankcase cover 22R that covers the right crankcase 21R from the right side.

FIG. 2 is a side view mainly showing the engine case 20 of the internal combustion engine E, FIG. 7 is a side view of the internal combustion engine E with the right crankcase cover 22R removed from the right crankcase 21R, and FIG. 8 is a side view showing a state in which the centrifugal clutch 70, the centrifugal separation type oil filter 75, and the transmission clutch 85 have been removed from the state of FIG.
Referring to FIGS. 7 and 8, right crankcase 21R has a side wall 21Rv perpendicular to the axial direction that supports crankshaft 40, main shaft 81, and the like, and an outer periphery extending in the axial direction from the outer peripheral edge of the side wall 21Rv. The surface 21Rsf (the dotted pattern portion in FIGS. 7 and 8) formed by the right crankcase cover 22R, which is the right open end surface of the outer peripheral wall 21Rs of the right crankcase 21R, is formed in an annular shape. .

  A centrifugal clutch 70 provided on the right shaft portion 40R of the crankshaft 40 projecting rightward from the side wall 21Rv of the right crankcase 21R inside the annular inner surface of the mating surface 21Rsf of the outer peripheral wall 21Rs of the right crankcase 21R. A transmission clutch 85 provided on the right-side shaft portion of the main filter 81 and the oil filter 75 is located (see FIG. 7).

As shown in FIG. 8, an oil pump cover 111 in which an oil pump 110 is formed is attached to the side wall 21Rv of the right crankcase 21R diagonally below and forward of the crankshaft 40 by fastening bolts 113.
A pump driven gear 112 fitted to the pump drive shaft 110a of the oil pump 110 meshes with a pump drive gear 51 fitted to the right shaft portion 40R of the crankshaft 40.
Therefore, the rotation of the crankshaft 40 is transmitted through the mesh between the pump drive gear 51 and the pump driven gear 112, and the oil pump 110 is driven.

Referring to FIG. 9, which is a cross-sectional view cut perpendicularly in the left-right direction at the outer peripheral wall 21Rs of the right crankcase 21R, the oil pump 110 is attached to the bottom wall 21Rsb of the outer peripheral wall 21Rs of the right crankcase 21R. An oil drain hole 101 is formed in the lower part of the figure.
The opening opened below the oil drain hole 101 is closed by the cap 103.
A wire mesh-shaped oil strainer 102 is inserted into the oil drain hole 101 while being held by a cap 103 via a spring.

  The oil drain hole 101 communicates with an oil reservoir 100 formed in the bottom walls 21Lsb, 21Rsb of the left and right crankcases 21L, 21R, and is provided in the oil drain hole 101 with an oil strainer held by a cap 103. The outside (upstream side) of 102 communicates with oil reservoir 100, and the inside (downstream side) of oil strainer 102 communicates with pumping oil passage 105P (see FIG. 8) extending to the suction port of oil pump 110. ing.

A discharge oil passage 115P extends from a discharge port of the oil pump 110.
The discharge oil passage 115P penetrates the oil pump cover 111 to the right, and forms a connection opening end face 115a on the right side of the oil pump cover 111 (see FIG. 8).

FIG. 10 is a perspective view of the right crankcase cover 22R obliquely viewed from the rear side, and the surface of the right crankcase cover 22R is shown in FIG.
As shown in FIG. 10, the right crankcase cover 22R that covers the right crankcase 21R from the right side extends rightward in the axial direction from the side wall 22Rv substantially perpendicular to the axial direction of the crankshaft 40 and the periphery of the side wall 22Rv. The outer peripheral wall 22Rs forms a rectangular bowl shape.

  In the right crankcase cover 22R, the left open end surface of the outer peripheral wall 22Rs is a mating surface 22Rsf, and is mated with the mating surface 21Rsf of the right crankcase 21R, so that the centrifugal clutch 70, the centrifugal oil filter 75, and the shift clutch 85 To cover the right side of the right crankcase 21R.

The side wall 22Rv that closes the right opening of the outer peripheral wall 22Rs of the right crankcase cover 22R forms a circular side wall 22Rva in which a portion facing the centrifugal clutch 70 and the centrifugal separation type oil filter 75 bulges further to the right. A cylindrically protruding bearing portion 143 is formed in the center of the circular side wall portion 22Rva, and the shaft end portion 40Rb of the right shaft portion 40R of the crankshaft 40 is rotatable in a bearing hole 143A inside the bearing portion 143. It is fitted (see FIG. 5).
Accordingly, as shown in FIG. 5, the shaft end opening of the first shaft oil passage 40A formed at the shaft end 40Rb of the right shaft portion 40R of the crankshaft 40 fitted into the bearing hole 143A is inserted into the bearing hole 143A. The first shaft internal oil passage 40A communicates with the bearing hole 143A.

As shown in FIG. 10, a plurality of ribs extend radially from the bearing portion 143 on the inner surface of the circular side wall portion 22Rva, of which a relatively wide rib 142 extending forward has an oil passage 142P formed therein. (See FIG. 5).
Further, a cylindrical rib 141 is formed on the inner surface of the front wall of the outer peripheral wall 22Rs of the right crankcase cover 22R so as to be oriented in the left-right direction which is the axial direction of the crankshaft 40, and is formed on the cylindrical rib 141. The right end of the oil passage 141P communicates with the front end of the oil passage 142P of the rib 142, and the left end of the cylindrical rib 141 is a connection opening end surface 141a.

An oil filter 120 with a built-in filter element is provided at the lower part on the front side of the outer peripheral wall 22Rs of the right crankcase cover 22R (see FIGS. 2 and 10).
Referring to FIGS. 2 and 3, cylindrical filter housing 121 of oil filter 120 is provided at corner wall portion 22Rsc between front wall portion 22Rsa and bottom wall portion 22Rsb of outer peripheral wall 22Rs of right crankcase cover 22R. Are formed so as to partially project outward.
The cylinder block 23 projects forward from the front wall of the right crankcase 21R, which constitutes the front wall of the engine case 20, together with the front wall 22Rsa of the right crankcase cover 22R.

The filter housing 121 having a cylindrical shape is opened to the right. The filter element 123 is inserted into the inside, and the opening is closed by the cover member 122.
The cover member 122 is fixed to the filter housing 121 by bolts 124.

The oil filter 120 is provided at a corner wall 22Rsc of the outer peripheral wall 22Rs of the right crankcase cover 22R so as to partially project obliquely downward and forward (see FIG. 2).
As shown in FIG. 2, the upper end of the oil filter 120 is substantially at the same height as the lower surface of the cylinder block 23, and is located above the lower surface of the bottom wall 22Rsb of the outer peripheral wall 22Rs of the right crankcase cover 22R. ing.

However, the oil filter 120 is disposed at a position lower than the oil pump 110, as shown by a virtual line in FIG.
As shown in FIG. 3, the lid member 122 at the right end of the oil filter 120 is retracted leftward from the right outer side surface of the circular side wall portion 22Rva projecting rightmost of the side wall 22Rv of the right crankcase cover 22R. It is in a position.

Referring to FIGS. 10 and 11, an inflow cylindrical portion 125 is formed in which a part of an upper wall of a cylindrical filter housing 121 of oil filter 120 bulges upward and extends to the left.
The left end of the inflow cylindrical portion 125 is a connection opening end surface 125a, and the right end of the inflow oil passage 125P inside the inflow cylindrical portion 125 communicates with the inside of the filter housing 121.

  The outflow oil passage 126P extending leftward from the center of the left side wall, which is the bottom wall of the filter housing 121, is bent upward and then further leftward, passes through the inside of the outflow cylindrical portion 126, and flows out of the outflow cylinder 126. The portion 126 has an opening at the left end of the connection opening end surface 126a.

  Here, the connection opening end surface 125a of the inflow cylindrical portion 125, the connection opening end surface 126a of the outflow cylindrical portion 126, and the connection opening end surface 141a of the cylindrical rib 141 formed near and above the inflow cylindrical portion 125 are the right crankcase cover. It is on the same plane as the mating surface 22Rsf of 22R.

  Referring to FIG. 8, the right crankcase 21R covered with the right crankcase cover 22R has a connection opening end face opened on the right side of a discharge oil passage 115P formed in an oil pump cover 111 constituting the oil pump 110. 115a is located at a position facing the connection opening end surface 125a of the inflow cylindrical portion 125 of the right crankcase cover 22R.

In the right crankcase 21R, at a position facing the connection opening end surface 126a of the outflow cylindrical portion 126 of the right crankcase cover 22R, a cylindrical rib 131 having a connection opening end surface 131a at the right end and extending in the left-right direction is provided on the outer peripheral wall 21Rs. (See FIG. 8).
8 and 11, an oil passage 132P extends upward intersecting the oil passage 131P inside the cylindrical rib 131, and intersects at the upper end of the oil passage 132P to form an oil passage 133P obliquely in the front-rear direction. Extending.

  The oil passage 133P extends obliquely forward to the mating surface of the cylinder block 23 and the right crankcase 21R. A cylindrical rib 134 forming an oil passage 134P branched rightward in the middle of the oil passage 133P extends along the outer peripheral wall 21Rs. It extends rightward (see FIG. 11), and has a connection opening end face 134a formed on the mating surface 21Rsf (see FIG. 8).

  When the oil passage 133P reaches the mating surface of the cylinder block 23 and the right crankcase 21R, the oil passage 133P bends and communicates with the oil passage 135P extending upward in a circular arc around the cylinder along the mating surface. Communicates with an oil passage 136P extending toward the cylinder head 24 in parallel with the cylinder axis Lc, and oil is supplied to the valve train through the oil passages 135P and 136P.

  When the mating surface 22Rsf of the right crankcase cover 22R is fitted to the mating surface 21Rsf of the right crankcase 21R, and the right crankcase cover 22R is put on the right crankcase 21R, the connection opening of the discharge oil passage 115P on the right crankcase 21R side is formed. The end surface 115a, the connection opening end surface 131a of the oil passage 131P, and the connection opening end surface 134a of the oil passage 134P are respectively corresponding to the connection opening end surface 125a of the inflow oil passage 125P and the connection opening end surface of the outflow oil passage 126P on the right crankcase cover 22R side. The oil passage 126a and the connection opening end surface 141a of the oil passage 141P are liquid-tightly matched, and the corresponding oil passages communicate with each other.

FIG. 11 is a perspective view in which an oil circulation path (portion indicated by a dotted pattern in FIG. 11) in the internal combustion engine E is seen through.
Referring to FIG. 11, oil accumulated in oil reservoirs 100 of left and right crankcases 21L, 21R is driven by oil pump 110 to remove relatively large foreign matter through oil strainer 102 in oil drain hole 101. Then, it is pumped through the pumping oil passage 105P.

  The oil discharged from the oil pump 110 passes through the discharge oil passage 115P, enters the inflow oil passage 125P on the right crankcase cover 22R side, flows into the oil filter 120, and fine foreign substances such as sludge and metal powder are removed by the filter element 123. It is removed and flows out through the outflow oil passage 126P.

The oil that has flowed out through the outflow oil passage 126P enters the oil passage 131P on the right crankcase 21R side, then passes through the oil passage 132P extending vertically, and enters the oil passage 133P that bends and extends in the front-rear direction.
The oil diverted to the oil passage 134P branched from the oil passage 133P enters the oil passage 141P on the right crankcase cover 22R side, and then bends and passes through the oil passage 142P of the rib 142 directed in the radial direction of the circular side wall 22Rva. Into the bearing hole 143A inside the bearing portion 143.

  Referring to FIG. 5, the oil that has entered bearing hole 143A flows into first axial oil passage 40A of right shaft portion 40R of crankshaft 40, and further flows from branch oil passage 40Aa to a centrifugal oil filter 75 in the annular shape. After entering the space 75 s, the rotation of the centrifugal oil filter 75 separates the foreign matter having a high specific gravity, such as metal powder, still mixed in the oil by centrifugal force, and the filtered oil flows out of the lead-out oil passage 61 a into the second shaft. Enter oilway 40B.

  Oil is supplied from the second shaft inner oil passage 40B to the inner peripheral surface of the outer cylinder member 54 through the branch oil passage 40Bb and to the inner peripheral surface of the primary drive gear 53 through the branch oil passage 40Bc to form a shaft support. While lubricating, oil is supplied from the second shaft oil passage 40B to the crankpin 40p through the branch oil passage 40Bd, and lubricates the shaft support portion with the connecting rod 43.

  In the case of the centrifugal oil filter 75 as a filtration device, it is necessary to first remove the right crankcase cover 22R from the right crankcase 21R because it is inside the right crankcase cover 22R during maintenance. The cover plate 76 of the 75 is removed to clean and remove the foreign substances accumulated on the inside, which is a rather troublesome maintenance work.

  On the other hand, since the oil filter 120 is provided so as to protrude from the right crankcase cover 22R, at the time of maintenance, the bolt 124 is removed, the lid member 122 is removed, and the filter element 123 in the filter housing 121 is pulled out. It is only necessary to replace the filter element with a new filter element and close the lid member 122, and the maintenance work is extremely simple.

The first embodiment of the lubrication structure for an internal combustion engine according to the present invention described in detail above has the following effects.
In the lubrication structure of the internal combustion engine E in which the right-side shaft portion 40R of the crankshaft 40 protruding laterally from the right crankcase 21R is provided with a centrifugal oil filter 75, as shown in FIG. An oil filter 120 having a built-in filter element 123 is provided in an oil passage extending from the oil pump 110 for pumping oil to the centrifugal oil filter 75, so that the entire oil capacity of the oil filter is significantly increased, and the frequency of maintenance is increased. Can be suppressed.

  The oil filter 120 replaces the filter element compared to the centrifugal oil filter 75, which is cleaned by maintenance. Maintenance is simpler. Maintenance of the separation type oil filter 75 can be performed extremely infrequently, and labor can be greatly reduced.

  As shown in FIGS. 2 and 3, the oil filter 120 is provided on the outer peripheral wall 22Rs, which is the outer wall of the right crankcase cover 22R. Therefore, there is no cover member that covers the oil filter 120 from outside, and the cover member is removed. The maintenance of the oil filter 120 can be performed more easily and in a shorter time without any work.

  As shown in FIG. 7, the oil filter 120 is provided on an outer peripheral wall 22Rs, which is the outer wall of the right crankcase cover 22R, and the centrifugal oil filter 75 attached to the right shaft portion 40R of the crankshaft 40 is different from the crankshaft. Since the shaft 40 is disposed at a position where it does not overlap when viewed in the axial direction, the width of the internal combustion engine E in the axial direction of the crankshaft 40 can be suppressed, and the size of the internal combustion engine can be reduced.

As shown in FIGS. 2 and 3, the oil filter 120 is provided on the relatively strong outer peripheral wall 22Rs of the right crankcase cover 22R, so that the oil filter 120 is securely provided and the outer peripheral wall 22Rs Can be further improved in strength and rigidity.
Further, the oil filter can be provided without increasing the width of the internal combustion engine E in the vehicle body width direction (the axial direction of the crankshaft), and it is possible to avoid an increase in the size of the internal combustion engine.

  As shown in FIGS. 2 and 7, the oil filter 120 is provided so as to partly protrude outside the outer peripheral wall 22Rs when viewed in the axial direction of the crankshaft 40, so that the oil filter 120 projects from the outer peripheral wall 22Rs. Is reduced as much as possible, and the penetration of the oil filter 120 into the outer peripheral wall 22Rs is also reduced, so that interference with the internal structure can be avoided.

In the internal combustion engine E, a cylinder block 23 is provided so as to protrude from the left and right crankcases 21L and 21R so that a cylinder axis Lc is substantially horizontal. As shown in FIG. Since it is provided on the corner wall portion 22Rsc between the front wall portion 22Rsa and the bottom wall portion 22Rsb of the outer peripheral wall 22Rs of the cover 22R, it constitutes the front wall portion of the engine case 20 together with the front wall portion 22Rsa of the right crankcase cover 22R. The oil filter 120 can be disposed in a dead space near the right crankcase cover 22R near the lower part of the cylinder block 23 that projects forward from the front wall of the right crankcase 21R (see FIGS. 2 and 3).
That is, it is possible to suppress the oil filter 120 from projecting vertically when viewed in the crankshaft direction.

  As shown in FIGS. 2 and 7, the oil filter 120 is located above the lower surface of the bottom wall 21Rsb of the left and right crankcases 21L and 21R in the engine case 20, so that the oil filter 120 is located below the lower surface of the bottom wall 21Rsb. The oil filter 120 does not protrude, and the required distance of the internal combustion engine E from the ground can be easily secured.

  As shown in FIGS. 8 and 11, the oil filter 120 is disposed below the oil pump 110, and therefore, when the internal combustion engine E stops operating, it is disposed below the stopped oil pump 110. Since the oil filter 120 is kept filled with oil, the oil can be circulated without delay at the time of restart.

As shown in FIG. 11, a relatively large foreign matter is removed by the oil strainer 102 in the oil drain hole 101 on the upstream side of the oil filter 120, so that the load on the oil filter 120 is reduced and deterioration is suppressed.
Also, as shown in FIG. 9, the oil strainer 102 inserted into the oil drain hole 101 is disposed while being held by the cap 103. By removing the cap 103 from the oil drain hole 101, the oil strainer 102 is cranked. The oil strainer 102 can be easily taken out of the case, and the maintenance of the oil strainer 102 can be easily performed.

  In the above-described first embodiment of the present invention, the oil filter 120 is provided on the crankcase cover (the right crankcase cover 22R) in the engine case 20, but the oil filter is provided on the crankcase. A second embodiment will be described with reference to FIG.

The internal combustion engine E according to the second embodiment is almost the same as the internal combustion engine E according to the first embodiment except for a structure in which an oil filter is provided in the right crankcase. Members other than 220 are denoted by the same reference numerals.
Although not shown, the oil passages flowing into and out of the oil filter 220 containing the filter element are different.

  The right crankcase 201 is composed of a side wall 201v perpendicular to the axial direction that supports the crankshaft 40, the main shaft 81 and the like, and an outer peripheral wall 201s extending in the axial direction from the outer peripheral edge of the side wall 201v. 12, a mating surface 201sf (a dotted pattern portion in FIG. 12) of the right opening end surface of the outer peripheral wall 201s of the right crankcase 201 with the right crankcase cover is shown in an annular shape.

  A centrifugal clutch 70 and a centrifugal oil filter provided on the right shaft of the crankshaft 40 projecting rightward from the side wall 201v of the right crankcase 201 inside the mating surface 201sf of the outer peripheral wall 201s of the right crankcase 201. 75 and a speed change clutch 85 provided on the right shaft portion of the main shaft 81 (see FIG. 7).

An oil filter 220 is provided at a lower portion on the front side of the outer peripheral wall 201s of the right crankcase 201.
A cylindrical filter housing 221 is formed on a corner wall 201sc of the outer peripheral wall 201s of the right crankcase 201 between the front wall 201sa and the bottom wall 201sb where the cylinder block 23 protrudes, and a part of the filter housing 221 projects outward. The filter housing 221 is opened rightward, the filter element 223 is inserted therein, and the opening is closed by the cover member 222.
The cover member 122 is fixed to the filter housing 221 by bolts 224.

As shown in FIG. 12, the mating surface 201sfa of the corner wall 201sc of the mating surface 201sf of the outer peripheral wall 201s of the right crankcase 201 has a filter housing 221 formed by projecting a part of the corner wall 201sc outward. It is formed so as to be depressed inward along the outer peripheral surface on the inside (crankshaft 40 side).
Therefore, the right crankcase cover (not shown) has a mating surface facing the mating surface 201sf of the right crankcase 201, and covers the right side of the right crankcase 201 avoiding the oil filter 220 outside.

  As described above, since the oil filter 220 is provided on the corner wall portion 201sc of the outer peripheral wall 201s of the right crankcase 201, the maintenance of the oil filter 220 can be performed without removing the right crankcase cover, without removing the cover member 122 exposed to the outside. By removing, the internal filter element 223 can be replaced, and a simple operation is completed.

Therefore, the oil filter 220 is provided in the oil passage from the oil pump to the centrifugal oil filter 75, so that the overall oil capacity of the oil filter is significantly increased, and the frequency of maintenance can be suppressed.
By performing simple maintenance of the oil filter 220, troublesome maintenance of the centrifugal oil filter 75 can be performed very infrequently and labor can be greatly reduced.

Since the oil filter 220 is provided on the outer peripheral wall 201s of the right crankcase 201, the maintenance of the oil filter 220 can be performed more easily and in a shorter time without performing the operation of removing the cover member.
Since the oil filter 220 is disposed at a position where the oil filter 220 and the centrifugal oil filter 75 do not overlap when viewed in the axial direction of the crankshaft 40, the width of the internal combustion engine E in the axial direction of the crankshaft 40 is suppressed to reduce the size of the internal combustion engine. Can be achieved.

The oil filter 220 is provided on the relatively strong outer peripheral wall 201s of the right crankcase 201, so that the oil filter 220 is firmly provided and the strength and rigidity of the outer peripheral wall 201s can be further improved.
The oil filter 220 is provided so as to partially protrude outside the outer peripheral wall 201s, so that the oil filter 220 protrudes from the outer peripheral wall 201s as small as possible, and the oil filter 220 inwardly projects from the outer peripheral wall 201s. Penetration can be reduced to avoid interference with the internal structure.

The oil filter 220 is provided on a corner wall 201sc of the outer peripheral wall 201s of the right crankcase 201 between the front wall 201sa where the cylinder block 23 projects forward and the bottom wall 201sb. The oil filter 120 can be arranged in a dead space near the right crankcase 201 of the vehicle.
That is, it is possible to suppress the oil filter 220 from projecting vertically when viewed in the crankshaft direction.
The oil filter 220 is located above the lower surface of the bottom wall portion 201sb of the right crankcase 201 in the engine case 20, so that the necessary distance of the internal combustion engine E from the ground can be easily secured.
The oil filter 220 can be arranged below the oil pump, and can circulate oil without delay at the time of restart.

Next, a third embodiment in which an oil filter is provided on the outer peripheral wall of the right crankcase will be described with reference to FIG.
The internal combustion engine E according to the third embodiment is substantially the same as the internal combustion engine E according to the first embodiment except for a structure in which an oil filter is provided in the right crankcase. Members other than 320 are indicated using the same reference numerals.

In the third embodiment, similarly to the second embodiment, the right crankcase 301 includes a side wall 301v and an outer peripheral wall 301s, and the right crankcase 301 extends from a front wall portion 301sa on which the cylinder block 23 protrudes. An oil filter 320 having a built-in filter element is provided in a corner wall portion 301sc extending to the bottom wall portion 301sb. Unlike the second embodiment, an oil filter 320 having an oil filter 320 is provided on the outer surface of the corner wall portion 301sc. A filter mounting seat 302 to which the case 321 is mounted is formed.
The filter case 321 having a cylindrical shape with a bottom has a filter element 323 accommodated therein, and a flange portion 321 f at an open end is fastened to the filter mounting seat 302 by bolts 324.

  The filter mounting seat 302 is provided on the outer surface of the outer peripheral wall 301s (corner wall portion 301sc) of the right crankcase 301, and is provided with a mating surface 301sf (see FIG. 13) with the right crankcase cover, which is the right opening end surface of the outer peripheral wall 301s. Dot).

Therefore, the maintenance of the oil filter 320 can be performed with a simple operation by removing the filter case 321 exposed to the outside without removing the right crankcase cover, so that the internal filter element 323 can be replaced.
In addition, in the third embodiment, the same effects as those in the second embodiment can be obtained.

  As described above, the lubrication structure for the internal combustion engine according to the three embodiments of the present invention has been described. However, aspects of the present invention are not limited to the above-described embodiments, but may be variously modified within the scope of the present invention. Includes what is implemented.

E: internal combustion engine, 1: motorcycle, 20: engine case, 21L: left crankcase, 22L: left crankcase cover,
21R: right crankcase, 21Rv: side wall, 21Rs: outer peripheral wall, 21Rsb: bottom wall, 21Rsf: mating surface,
22R: right crankcase cover, 22Rv: side wall, 22Rva: circular side wall, 22Rs: outer peripheral wall, 22Rsa: front wall, 22Rsb: bottom wall, 22Rsc: corner wall, 22Rsf: mating surface,
23 ... cylinder block, 24 ... cylinder head,
40 ... Crankshaft, 40L ... Left shaft, 40R ... Right shaft, 40Ra ... Spline shaft, 40Rb ... Shaft end, 40A ... First shaft oil passage, 40B ... Second shaft oil passage, 41 ... Main Bearing, 54: outer cylinder member, 60: drive plate, 61: annular boss member, 70: centrifugal clutch,
75: Centrifugal oil filter, 76: Cover plate, 77: Annular seal member, 78: Bolt, 100: Oil reservoir, 101: Oil drain hole, 102: Oil strainer, 103: Cap, 105P: Pumping oil passage ,
110: oil pump, 111: oil pump cover, 115P: discharge oil passage,
120 ... oil filter, 121 ... filter housing, 122 ... lid member, 123 ... filter element, 124 ... bolt, 125 ... inflow cylinder, 125 P ... inflow oil passage, 126 ... outflow cylinder, 126 P ... outflow oil passage, 131 ... Cylindrical ribs, 131P, 132P, 133P: oil passage, 134: cylindrical rib, 134P: oil passage, 135P, 136P: oil passage, 141: cylindrical rib, 141P, 142P: oil passage, 142: rib, 143 ... Bearing part, 143A ... bearing hole,
201 ... right crankcase, 201s ... outer peripheral wall, 201sa ... front wall, 201sb ... bottom wall, 201sc ... corner wall, 201sf ... mating surface, 220 ... oil filter, 221 ... filter housing, 222 ... lid member, 223 ... filter element, 224 ... bolt,
301 ... right crankcase, 301s ... outer peripheral wall, 301sa ... front wall, 301sb ... bottom wall, 301sc ... corner wall, 301sf ... mating surface, 302 ... filter mounting seat, 320 ... oil filter, 321 ... filter case, 323 ... filter element, 324 ... bolt.

Claims (12)

A crankcase (21L, 21R) that rotatably supports the crankshaft (40); and a pair of crankcases that cover the crankcase (21L, 21R) from both sides in the direction in which the crankshaft (40) is directed. The cover (22L, 22R) forms an engine case (20),
An oil reservoir (100) on the bottom wall of the crankcase (21L, 21R);
In a lubricating structure for an internal combustion engine, a centrifugal oil filter (75) is provided on a shaft portion of the crankshaft (40) protruding laterally from the crankcase (21L, 21R).
An oil passage is provided from the oil pump (110) for pumping oil from the oil reservoir (100) to the centrifugal oil filter (75), and the oil passage is provided in a cylindrical filter housing (121). A filtration oil filter (120) incorporating an element (123) is provided;
The oil pump (110) is mounted inside the crankcase (21L, 21R),
A cylindrical filter housing (121) of the filtration type oil filter (120) is formed on an outer peripheral wall (22Rs) of one (22R) of the crankcase covers (22L, 22R) so as to extend along the crankshaft (40). And
On the peripheral wall of the cylindrical filter housing (121) of the filtration type oil filter (120), an oil inflow cylinder portion (125) having an inflow oil passage (125P) from the oil pump (110) is provided. Formed along the longitudinal direction of the filter housing (121),
An oil outflow cylindrical portion (126) forming an oil outflow passage (126P) extends from an end wall of the cylindrical filter housing (121) of the filtration type oil filter (120),
An oil passage (141P) for connecting the oil outflow passage (126P) of the filtration oil filter (120) to the centrifugal oil filter (75) is provided in one (22R) of the crankcase covers (22L, 22R). ) Is formed,
A lubrication structure for an internal combustion engine, wherein the inflow oil passage (125P), the oil outflow passage (126P), and the oil passage (141P) to the centrifugal oil filter (75) are parallel to each other. .   The lubrication structure for an internal combustion engine according to claim 1, wherein the oil filter (120) is provided on an outer wall of the engine case (20).   The internal combustion engine according to claim 2, wherein the oil filter (120) is disposed at a position that does not overlap the centrifugal oil filter (75) when viewed in the axial direction of the crankshaft (40). Lubrication structure.   The oil filter (120) is provided on an outer peripheral wall (22Rs) extending in the axial direction from a peripheral edge of a side wall substantially perpendicular to the axial direction of the crankshaft (40) in the engine case (20). The lubricating structure for an internal combustion engine according to claim 3, wherein:   The lubrication of an internal combustion engine according to claim 4, wherein a part of the oil filter (120) is provided to protrude outside the outer peripheral wall (22Rs) when viewed in an axial direction of the crankshaft (40). Construction. The internal combustion engine is provided with a cylinder block (23) projecting from the crankcase (21L, 21R) such that a cylinder axis (Lc) is substantially horizontal.
The oil filter is provided on a corner wall (22Rsc) of the outer peripheral wall (22Rs) of the engine case (20) between a wall (22Rsa) from which the cylinder block (23) projects and a bottom wall (22Rsb). The lubricating structure for an internal combustion engine according to claim 4 or 5, wherein (120) is provided.   The lubrication structure for an internal combustion engine according to claim 6, wherein the oil filter (120) is located above a lower surface of the bottom wall (22Rsb).   The lubricating structure for an internal combustion engine according to any one of claims 1 to 7, wherein the oil filter (120) is disposed below the oil pump (110). An oil drain hole (101) communicating with the oil reservoir (100) is formed in a bottom wall (22Rsb) of the crankcase (21L, 21R) so as to open downward,
The opening of the oil drain hole (101) is closed by a cap (103),
An oil strainer (102) held by the cap is disposed in the oil drain hole (101),
An upstream side of the oil strainer (102) is communicated with the oil reservoir (100),
9. The oil pump according to claim 1, wherein a downstream side of the oil strainer is communicated with a pumping oil passage of oil pumped by the oil pump. 10. Lubrication structure of internal combustion engine.   An end surface (126a) of the oil outflow cylindrical portion (126) and an end surface (141a) of the oil passage (141P) connected to the centrifugal oil filter (75) are coplanar. The lubricating structure for an internal combustion engine according to claim 1.   The discharge port of the oil pump (110) and the opening end surface (125a) of the oil inflow cylindrical portion (125) of the filtration type oil filter (120) are located at substantially the same height. The lubricating structure for an internal combustion engine according to claim 1 or 2.   The inflow oil passage (125P) of the filtration type oil filter (120) and the connection oil passage (141P) to the centrifugal separation type oil filter (75) are, as viewed from the side, the centrifugal separation type oil filter (75). 3. The lubrication structure for an internal combustion engine according to claim 1, wherein the lubrication structure overlaps with an oil passage in a crankcase that is connected to the connection oil passage.

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