JP2018178743A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine which can utilize a drain plug, and can effectively remove magnetic material refuse contained in lubricating oil.SOLUTION: An engine 11 includes: a crankcase 41 having an oil pan 57 which can store lubricating oil, and a drain port 85 which can deliver the lubricating oil from the oil pan 57; an oil pump 81 for pumping up the lubricating oil from the oil pan 57; a filter upstream side oil passage 83 for guiding the lubricating oil from the oil pan 57 to the oil pump 81; a first oil filter 82 provided in the filter upstream side oil passage 83; a drain plug 87 which closes the drain port 85 and reaches the inside of the filter upstream side oil passage 83 connecting the first oil filter 82 and the oil pan 57; and a magnet 88 which is provided on the drain plug 87 and is arranged in the filter upstream side oil passage 83.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an internal combustion engine.

  An internal combustion engine is known that is provided with a drain bolt that is removably mounted to the lower portion of the oil pan.

  The drain bolt has a concave surface facing the oil pan. The concave is provided with a magnet. In the conventional internal combustion engine, even if dust of magnetic material of a size that can pass through the oil strainer is mixed in the oil pan, these dusts are adsorbed to the magnet (see, for example, Patent Document 1).

JP, 2005-009346, A

  The conventional internal combustion engine is provided with a magnet disposed at a location corresponding to the bottom surface of the oil pan, that is, the concave surface of the drain bolt. That is, the magnet is disposed in the oil pan.

  By the way, a large amount of lubricating oil is stored in the oil pan. For this reason, the lubricating oil in the oil pan does not reach a sufficient flow velocity except in the vicinity of the mouth of the oil strainer. For example, lubricating oil is stagnant at a place such as a concave surface of a drain bolt or at the bottom of an oil pan.

  That is, the magnet disposed in the oil pan can not touch a sufficient amount of lubricating oil. Therefore, the magnet of the conventional engine can not remove the refuse of the magnetic material contained in lubricating oil efficiently.

  Therefore, an object of the present invention is to provide an internal combustion engine that can use a drain plug and can efficiently remove dust of a magnetic material contained in lubricating oil.

  In order to solve the above problems, an internal combustion engine according to the present invention comprises a crankcase having an oil reservoir capable of storing lubricating oil, and a drain port capable of discharging the lubricating oil from the oil reservoir, and the oil An oil pump for sucking up the lubricating oil from a storage unit, an oil passage for guiding the lubricating oil from the oil storage unit to the oil pump, an oil filter provided in the oil passage, and closing the drain port A drain plug reaching the oil passage connecting the filter and the oil storage portion, and a magnet portion provided on the drain plug and disposed in the oil passage are provided.

  According to the present invention, it is possible to provide an internal combustion engine that can use the drain plug and can efficiently remove the dust of the magnetic material contained in the lubricating oil.

FIG. 1 is a left side view showing an example of a motorcycle to which an internal combustion engine according to an embodiment of the present invention is applied. FIG. 1 is a front view showing an internal combustion engine according to an embodiment of the present invention. FIG. 1 is a left side view showing an internal combustion engine according to an embodiment of the present invention. 1 is a schematic diagram of a lubrication system of an internal combustion engine according to an embodiment of the present invention. Sectional drawing of the principal part of the internal combustion engine which concerns on embodiment of this invention in the VV line | wire of FIG. Sectional drawing of the principal part of the internal combustion engine which concerns on embodiment of this invention in the VI-VI line of FIG. FIG. 7 is a perspective view of FIG.

  An embodiment of an internal combustion engine according to the present invention will be described with reference to FIGS. 1 to 7.

  FIG. 1 is a left side view showing an example of a motorcycle to which an internal combustion engine according to an embodiment of the present invention is applied.

  The expressions of front and rear, up and down, and left and right in the present embodiment are based on the occupant of the motorcycle 1.

  As shown in FIG. 1, the motorcycle 1 according to the present embodiment includes a vehicle body frame 2 extending in the front and rear direction, a front wheel 5 disposed in front of the vehicle body frame 2, and a front wheel 5 disposed at a front end of the vehicle body frame 2. The steering mechanism 6 rotatably supporting the rear wheel 7, the rear wheel 7 disposed to the rear of the vehicle body frame 2, the swing arm 8 disposed at the rear of the vehicle body frame 2 to rotatably support the rear wheel 7, And an internal combustion engine 11 (hereinafter simply referred to as "the engine 11") to be mounted. In addition, the motorcycle 1 is disposed above the front half of the vehicle body frame 2 and stores fuel supplied to the engine 11, and a seat disposed above the rear half of the vehicle body frame 2 for seating an occupant. 13 and a vehicle body cover 15 that covers a part of the vehicle body frame 2.

  The vehicle body frame 2 is a so-called cradle type. The vehicle body frame 2 includes a plurality of steel hollow tubes combined together. That is, the vehicle body frame 2 includes the head pipe 21, the main tube 22, the down tube 23, the pair of left and right seat rails 25, and the pair of left and right seat pillars 26.

  The head pipe 21 is disposed at the upper end of the front end of the vehicle body frame 2. The head pipe 21 supports the steering mechanism 6 so as to steer in the left and right direction of the vehicle.

  The main tube 22 extends obliquely downward and downward from the front end connected to the upper portion of the rear surface of the head pipe 21 and is curved halfway and hangs downward.

  The down tube 23 extends rearward from the front end connected below the rear surface of the head pipe 21 while being inclined further downward than the main tube 22 and is curved halfway toward the rear.

  The pair of left and right seat rails 25 branch from the front end connected to the curved portion of the main tube 22, and extend obliquely backward and gently upward.

  The pair of left and right seat pillars 26 diverges from the front end connected to the lower end of the main tube 22 and extends diagonally upward to the rear, and merges with the middle portion of the length of the seat rail 25 to seat Supporting

  The steering mechanism 6 includes a suspension mechanism (not shown) and has a pair of left and right front forks 27 rotatably supporting the front wheel 5, a front fender 28 covering the front wheel 5 and a top portion of the front fork 27. And a handle 29 to be fixed.

  The front wheel 5 is sandwiched between the left and right front forks 27 and rotates about an axle built over the lower ends of the left and right front forks 27.

  The swing arm 8 is supported by a pivot shaft (not shown) provided on the vehicle body frame 2 and can swing in the vertical direction. An axle for rotatably supporting the rear wheel 7 is provided at the rear end of the swing arm 8. The rear cushion unit 31 is bridged between the vehicle body frame 2 and the swing arm 8. The rear cushion unit 31 buffers the force transmitted from the rear wheel 7 to the vehicle body frame 2.

  The drive chain 32 transmits the output of the engine 11 to the rear wheel 7 to rotate the rear wheel 7.

  The engine 11 is disposed between the main tube 22 and the down tube 23 and fixed to the main tube 22 and the down tube 23.

  An oil cooler 33 for cooling lubricating oil that lubricates and cools each part of the engine 11 is provided diagonally in front of and above the engine 11. The oil cooler 33 is preferably disposed away from the position where the front fender 28 and the front wheel 5 face the front so as to be easily exposed to the traveling wind of the motorcycle 1.

  The fuel tank 12 is supported exclusively by the main tube 22. The fuel tank 12 is expanded from immediately after the head pipe 21 to the vicinity of the front end of the seat rail 25.

  The seat 13 is provided at the rear of the fuel tank 12. The seat 13 straddles the left and right seat rails 25 and reaches the rear end of the seat rail 25.

  The body cover 15 includes a front cover 35 made of synthetic resin, a pair of left and right side covers 36, and a rear cover 37.

  The front cover 35 is provided in front of the head pipe 21. The front cover 35 is fixed to the steering mechanism 6.

  The side cover 36 is connected below the rear of the fuel tank 12 and spreads in an inverted triangle over the main tube 22, the seat rail 25 and the seat pillar 26 and sandwiches them from the left and right.

  The rear cover 37 is connected to the lower ends of the left and right side surfaces of the rear half of the seat 13 to expand rearward, and extends to the rear of the seat 13 to merge.

  Next, the engine 11 according to the present embodiment will be described in detail.

  FIG. 2 is a front view showing an internal combustion engine according to an embodiment of the present invention.

  FIG. 3 is a left side view showing an internal combustion engine according to an embodiment of the present invention.

  As shown in FIGS. 2 and 3, the engine 11 according to the present embodiment has a small displacement of, for example, 50 cc class or 250 cc class. Also, the engine 11 is a four-stroke single cylinder. The engine 11 includes a crankcase 41 disposed in the lower half, a cylinder 42 connected to the upper front of the crankcase 41, a cylinder head 43 closing the top of the cylinder 42, and a head cover closing the top of the cylinder head 43 A transmission case 45 integrated with the crankcase 41 is provided.

  The crankcase 41 is made of aluminum alloy. The crankcase 41 includes a left case half 46 and a right case half 47. That is, the crankcase 41 can be divided into right and left. The left and right case halves 46, 47 are combined at a coupling surface 41a substantially orthogonal to the rotation center line of a crankshaft (not shown).

  The crankcase 41 further includes a left case cover 48 provided on the left side of the left case half 46 and a right case cover 49 provided on the right of the right crankcase half 47. The left case cover 48 is a magneto cover, and the right case cover 49 is a clutch cover.

  The cylinder 42 is coupled to the crankcase 41 in a forwardly inclined posture in which a center line of a cylinder bore (not shown), that is, a moving direction of a piston (not shown) is slightly inclined forward.

  At the front of the cylinder head 43, an outlet flange 43a of an exhaust port (not shown) is provided. An inlet flange 43 b of an intake port (not shown) is provided on the rear surface of the cylinder head 43.

  The transmission case 45 divides the transmission chamber 51.

  An oil cooler 33 is connected to the engine 11 via oil hoses 52 and 53.

  The oil cooler 33 is provided with a fan 55 that generates a cooling air. The oil cooler 33 cools the oil flowing from the oil hose 52 by the wind of the fan 55 and the traveling wind of the motorcycle 1 and returns the oil after the cooling from the oil hose 53 to the engine 11.

  The oil hoses 52, 53 extend from the corners of the front wall and the left side wall of the cylinder 42 to the oil cooler 33. The oil hoses 52, 53 distribute oil between the engine 11 and the oil cooler 33. An oil hose 52 disposed below sends oil from the engine 11 to the oil cooler 33. An oil hose 53 disposed above returns oil from the oil cooler 33 to the engine 11.

  FIG. 4 is a schematic system diagram of a lubrication system of an internal combustion engine according to an embodiment of the present invention.

  As shown in FIG. 4, the engine 11 according to the present embodiment includes an oil passage 56 provided in the crankcase 41, the cylinder 42, and the cylinder head 43.

  Further, the engine 11 is provided with an oil pan 57 as an oil reservoir provided at the bottom of the crankcase 41 for storing lubricating oil.

  The engine 11 supplies lubricating oil from the oil pan 57 to the crankshaft 58, the piston 59, the valve mechanism 61, the countershaft 62, and the drive shaft 63 to lubricate them.

  The crankshaft 58 is rotatably supported in a crank chamber (not shown) of the crankcase 41. The piston 59 is accommodated in a cylinder bore (not shown) of the cylinder 42 so as to be capable of reciprocating. The valve operating mechanism 61 is accommodated in a valve operating chamber (not shown) of the cylinder head 43. The counter shaft 62 and the drive shaft 63 are accommodated in a transmission chamber (not shown) of the transmission case 45.

  The oil cooler 33 is disposed above the highest point of the oil passage 56. The oil cooler 33 cools the lubricating oil (not shown) flowing through the oil passage 56.

  The oil passage 56 b of the cylinder 42 includes a first oil passage 71 directly connected to the cylinder head 43, a second oil passage 72 connected to the oil cooler 33 via the oil hose 52, and an oil cooler 33 via the oil hose 53. And a third oil passage 73 connected to the cylinder head 43.

  The oil passage 56c of the cylinder head 43 has a fourth oil passage 74 for guiding the lubricating oil flowing from the first oil passage 71 of the cylinder 42 to the valve mechanism 61, and the lubricating oil flowing from the third oil passage 73 for the cylinder 42 And a fifth oil passage 75 for cooling the circumference of the space 65.

  The oil passage 56 b of the cylinder 42 includes a sixth oil passage 76 for circulating the lubricating oil flowing from the fifth oil passage 75 of the cylinder head 43 around the combustion chamber 66, and the lubricating oil from the sixth oil passage 76 into the crankcase 41. And return oil passage 77.

  Further, the engine 11 is discharged from an oil pump 81 that sucks in lubricating oil from an oil pan 57, a first oil filter 82 that removes foreign substances from lubricating oil passing through the oil passage 56a of the crankcase 41, and oil pump 81 And a second oil filter 84 for removing foreign matter from the lubricating oil.

  The oil pump 81 is disposed below the crankshaft 58. The oil pump 81 is driven by an accessory drive gear (not shown) integral with the crankshaft 58. The output of the oil pump 81 depends on the rotational speed of the crankshaft 58, that is, the rotational speed of the engine 11, and as the rotational speed increases, more oil is discharged. By driving the oil pump 81, the oil in the oil pan 57 is sucked into the oil passage 56 a of the crankcase 41 and reaches the first oil filter 82. Here, in the oil passage 56 a of the crankcase 41, the portion connecting the oil pan 57 and the first oil filter 82 is referred to as a filter upstream oil passage 83. The filter upstream side oil passage 83 leads the lubricating oil from the oil pan 57 to the first oil filter 82.

  The lubricating oil which has passed the first oil filter 82 and the foreign matter has been removed is sucked into the oil pump 81. The lubricating oil sucked into the oil pump 81 is pressurized by the oil pump 81 and discharged from the oil pump 81. The lubricating oil discharged from the oil pump 81 reaches the second oil filter 84. The second oil filter 84 is a finer filter than the first oil filter 82.

  The lubricating oil which has passed the second oil filter 84 and from which the foreign matter has been removed flows from the oil passage 56 a of the crankcase 41 into the oil passage 56 b of the cylinder 42. The lubricating oil flowing into the oil passage 56 b of the cylinder 42 branches into a first oil passage 71 and a second oil passage 72. The lubricating oil branched in the cylinder 42 and flowing into the second oil passage 72 is cooled by the oil cooler 33 through the second oil passage 72 of the cylinder 42 and the oil hose 52. The lubricating oil cooled by the oil cooler 33 passes through the oil hose 53 and the third oil passage 73 to the fifth oil passage 75 of the cylinder head 43. The lubricating oil that has passed through the fifth oil passage 75 and has cooled the exhaust port 65 flows into the sixth oil passage 76 and cools the combustion chamber 66. The lubricating oil that has passed through the sixth oil passage 76 and has cooled the combustion chamber 66 is discharged from the return oil passage 77 into the crankcase 41 and returned to the oil pan 57.

  The lubricating oil branched into the cylinder 42 and flowing into the first oil passage 71 ascends the cylinder 42 upward and reaches the fourth oil passage 74 of the cylinder head 43 to lubricate the valve mechanism 61.

  FIG. 5 is a cross-sectional view of the main part of the internal combustion engine according to the embodiment of the present invention taken along the line V-V in FIG.

6 is a cross-sectional view of the main part of the internal combustion engine according to the embodiment of the present invention taken along the line VI-VI in FIG.
FIG. 7 is a perspective view of FIG.

  As shown in FIGS. 5 to 7, the crankcase 41 of the engine 11 according to the present embodiment has a drain port 85 capable of discharging the lubricating oil from the oil pan 57.

  The drain port 85 is provided on a wall 86 that divides the oil pan 57, that is, on the bottom wall of the crankcase 41. The drain port 85 is provided in the left case half body 46. The drain port 85 is preferably disposed at the lowest position of the crankcase 41.

  The engine 11 closes the drain port 85 and is provided in the drain plug 87 which reaches the inside of the filter upstream oil passage 83 connecting the first oil filter 82 and the oil pan 57, and provided on the drain plug 87 and on the filter upstream side. And a magnet portion 88 disposed in the oil passage 83.

  The first oil filter 82 is provided on the left case half 46. The first oil filter 82 is disposed in a filter accommodating portion 89 opened to the left of the left case half 46. The filter housing 89 is closed by the left case cover 48, that is, the magneto cover.

  The filter upstream oil passage 83 is separated from the bottom wall of the crankcase 41. In other words, the wall 91 defining the filter upstream side oil passage 83 and the wall 86 defining the oil pan 57 are separated from each other. The gap between the wall 91 defining the filter upstream side oil passage 83 and the wall 86 defining the oil pan 57 is part of the oil pan 57 storing lubricating oil. This gap is usually filled with the lubricating oil stored in the oil pan 57.

  The filter upstream oil passage 83 substantially extends over the entire width of the crankcase 41. The suction port 83 a of the filter upstream side oil passage 83 is provided at the center in the width direction of the crankcase 41. That is, the suction port 83a straddles the joint surface 41a of the left case half 46 and the right case half 47. The suction port 83 a faces the bottom surface of the oil pan 57, that is, the inner surface of the wall 86 that divides the oil pan 57.

  The discharge port 83 b of the filter upstream side oil passage 83 is connected to the filter accommodating portion 89.

  The drain plug 87 is made of an iron-based alloy. The drain plug 87 extends from the wall 86 partitioning the oil pan 57 to the wall 91 partitioning the upstream filter oil passage 83. The drain plug 87 has a so-called bolt-like male screw 95. Therefore, the engine 11 is provided with a wall 91 defining the filter upstream side oil passage 83, and a female screw 96 provided on the wall 86 defining the oil pan 57 and capable of fastening the drain plug 87. In other words, the wall 91 defining the filter upstream side oil passage 83 and the wall 86 defining the oil pan 57 have an internal thread portion 96 to which the drain plug 87 can be fastened. That is, while the drain plug 87 is screwed into the female screw portion 96a of the wall 86 partitioning the oil pan 57 to prevent the lubricating oil from leaking out from the drain port 85, the female screw of the wall 91 partitioning the filter upstream side oil passage 83 It is screwed into the portion 96 b to prevent the lubricating oil in the oil pan 57 from being sucked into the upstream oil passage 83 from the female screw portion 96 b. The female screw 96a and the female screw 96b are disposed on the same line.

  As shown in FIGS. 6 and 7, the internal thread portion 96 passes through the discharge port 83b of the filter upstream side oil passage 83 and extends on the surface extending in the front-rear direction of the engine 11 (the cross section shown in FIGS. 6 and 7). Is located in That is, the drain plug 87 is disposed on the surface extending in the front-rear direction of the engine 11 through the discharge port 83 b of the filter upstream side oil passage 83.

  The engine 11 is provided with a boss portion 97 provided between a wall 91 that defines the filter upstream side oil passage 83 and a wall 86 that defines the oil pan 57. The boss portion 97 has an internal thread portion 96 and a relay hole 98 connecting the internal thread portion 96 and the oil pan 57. When the drain plug 87 is removed from the engine 11, the lubricating oil stored in the oil pan 57 passes from the relay hole 98 to the drain port 85, that is, the female screw 96 a of the wall 86 defining the oil pan 57 to the outside of the engine 11. Discarded.

  The suction port 83a of the filter upstream side oil passage 83 is closer to the end of the externally threaded portion 95 of the drain plug 87, that is, the wall 86 defining the oil pan 57 than the portion farthest from the wall 86 defining the oil pan 57.

  The magnet portion 88 is provided at the non-threaded portion of the drain plug 87, specifically at the tip of the male screw portion 95. For example, in the case of the drain plug 87 having a cylindrical portion on the tip end side of the male screw portion 95, the magnet portion 88 is provided on the cylindrical portion on the tip side of the male screw portion 95. The magnet unit 88 is exposed to the filter upstream side oil passage 83. The magnet portion 88 is also disposed on a surface extending in the front-rear direction of the engine 11 through the discharge port 83 b of the filter upstream side oil passage 83.

  In addition, the filter upstream side oil passage 83 has a recess 99 in which the magnet portion 88 can be disposed. The recess 99 is provided at a position facing the female screw 96 b in the wall 91 that divides the filter upstream side oil passage 83. The magnet portion 88 may enter into the recess 99 (the magnet portion 88 shown by a two-dot chain line in FIG. 6) or may not enter into the recess 99. The recess 99 bulges from the wall 91 defining the filter upstream oil passage 83 toward the transmission chamber 51. In other words, a part of the wall 91 which partitions the filter upstream side oil passage 83 reaches the inside of the transmission chamber 51. A recess 99 is provided in this portion. That is, the filter upstream side oil passage 83 is sunk in the lubricating oil stored in the oil pan 57 and reaches below the transmission chamber 51.

  When the oil pump 81 is driven, the oil in the oil pan 57 is sucked into the filter upstream oil passage 83 from the suction port 83 a of the filter upstream oil passage 83. At this time, in the filter upstream side oil passage 83, a flow of lubricating oil toward the discharge port 83b is generated. The flow of lubricating oil is sent to various parts of the engine 11 through the first oil filter 82. The magnet portion 88 is exposed to the flow in the filter upstream side oil passage 83. That is, the magnet unit 88 is disposed at the location where the lubricating oil circulating in the engine 11 most frequently passes.

  The engine 11 according to the present embodiment is provided in the drain plug 87 that reaches the inside of the filter upstream side oil passage 83 that closes the drain port 85 and connects the first oil filter 82 and the oil pan 57, and provided in the drain plug 87 And a magnet portion 88 disposed in the filter upstream side oil passage 83. Therefore, in the engine 11, the magnet portion 88 is disposed at a position where the lubricating oil circulating in the engine 11 passes most frequently, and the magnet portion 88 is brought into contact with a large amount of lubricating oil to efficiently remove dust of magnetic material. Do.

  Further, the engine 11 according to the present embodiment is provided with a wall 91 which is separated from the wall 86 which divides the oil pan 57 and which divides the filter upstream side oil passage 83. Therefore, the engine 11 can easily ensure the length of the female screw portion 96 for tightening the drain plug 87.

  Furthermore, the engine 11 according to the present embodiment is provided with a wall 91 that divides the filter upstream side oil passage 83, and a female screw 96 that is provided on the wall 86 that divides the oil pan 57 and can fasten the drain plug 87. . Therefore, the engine 11 can reduce the risk of breakage of the internal thread portion 96 due to the fastening of the drain plug 87.

  Furthermore, in the engine 11 according to the present embodiment, the filter upstream side oil closer to the wall 86 that divides the oil pan 57 than the tip of the externally threaded portion 95 of the drain plug 87, that is, the part farthest from the wall 86 that divides the oil pan 57 most. The suction port 83a of the passage 83 is provided. Therefore, the engine 11 prevents the suction port 83a from deviating from the lubricating oil stored in the oil pan 57, ensures the suction performance of the oil pump 81, and facilitates the length of the female screw portion 96 for tightening the drain plug 87. Can be secured.

  Furthermore, the engine 11 according to the present embodiment includes the filter upstream oil passage 83 having the recess 99 in which the magnet unit 88 can be disposed. Therefore, in the engine 11, the magnet portion 88 can be disposed to cross the filter upstream side oil passage 83 up and down, and the contact area between the lubricating oil and the magnet portion 88 is ensured to be large.

  Further, the engine 11 according to the present embodiment is provided with a recessed portion 99 which is bulging into the transmission chamber 51. Therefore, the engine 11 can arrange the filter upstream side oil passage 83 on the transmission chamber 51 side while avoiding the crank chamber having a small space in the space.

  Furthermore, the engine 11 according to the present embodiment includes a boss 97 having a relay hole 98. Therefore, while the drain plug 87 can be made to reach the filter upstream side oil passage 83 on the extension of the drain port 85, the engine 11 can surely discard the lubricating oil of the oil pan 57, and maintainability is not impaired.

  Therefore, according to the engine 11 according to the present embodiment, the drain plug 87 can be used, and the dust of the magnetic material contained in the lubricating oil can be efficiently removed.

  DESCRIPTION OF SYMBOLS 1 motorcycle motorcycle 2 vehicle body frame 5 front wheel 6 steering mechanism 7 rear wheel 8 swing arm 11 internal combustion engine (engine) 12 fuel tank 13 seat 15 vehicle body cover , 21 ... head pipe, 22 ... main tube, 23 ... down tube, 25 ... seat rail, 26 ... seat pillar, 27 ... front fork, 28 ... front fender, 29 ... handle, 31 ... rear cushion unit, 32 ... drive chain 33: Oil cooler, 35: Front cover, 36: Side cover, 37: Rear cover, 41: Crankcase, 41a: Coupling surface, 42: Cylinder, 43: Cylinder head, 43a: Outlet flange, 43b: Inlet flange, 44 ... head cover, 45 ... transmission case, 46 ... left side case half body, 7 right side case half body 48 left side case cover 49 right side case cover 51 transmission room 52, 53 oil hose 55 fan 56 oil passage 56a crankcase oil passage 56b ... Oil passage of cylinder, 56c ... Oil passage of cylinder head, 57 ... Oil pan, 58 ... Crankshaft, 59 ... Piston, 61 ... Valve mechanism, 62 ... Counter shaft, 63 ... Drive shaft, 65 ... Exhaust port, 66 ... combustion chamber, 71 ... first oil passage, 72 ... second oil passage, 73 ... third oil passage, 74 ... fourth oil passage, 75 ... fifth oil passage, 76 ... sixth oil passage, 77 ... return oil Passage, 81 ... oil pump, 82 ... first oil filter, 83 ... filter upstream oil passage, 83 a ... suction port, 83 b ... discharge Reference numeral 84: second oil filter 85: drain port 86: wall partitioning oil pan 87: drain plug 88: magnet portion 89: filter housing portion 91: wall partitioning filter upstream oil passage , 95: Male thread portion 96: Female thread portion 96a: Female thread portion of wall defining oil pan 96b: Female thread portion of wall defining oil passage upstream of filter 97: Boss portion 98: Relay hole 99: Recessed part.

Claims (8)

A crankcase having an oil storage portion capable of storing lubricating oil, and a drain port capable of discharging the lubricating oil from the oil storage portion;
An oil pump for sucking the lubricating oil from the oil reservoir;
An oil passage for guiding the lubricating oil from the oil reservoir to the oil pump;
An oil filter provided in the oil passage;
A drain plug that blocks the drain port and reaches the inside of the oil passage that connects the oil filter and the oil reservoir;
And a magnet portion provided in the drain plug and disposed in the oil passage. The internal combustion engine according to claim 1, wherein a wall partitioning the oil passage is separated from a wall partitioning the oil reservoir. The internal combustion engine according to claim 1 or 2, further comprising: a wall partitioning the oil passage, and an internal thread portion provided on the wall partitioning the oil storage portion and capable of fastening the drain plug. The inlet according to any one of claims 1 to 3, wherein the oil passage sucks in the lubricating oil from the oil reservoir and is closer to a wall partitioning the oil reservoir than a tip end of an external thread of the drain bolt. Internal combustion engine. The internal combustion engine according to any one of claims 1 to 4, wherein the oil passage has a recess in which the magnet unit can be disposed. A transmission case integrated with the crankcase to define a transmission chamber;
6. The internal combustion engine according to claim 5, wherein the recess bulges from the wall defining the oil passage into the transmission chamber. The crankcase is made of an aluminum alloy,
The internal combustion engine according to any one of claims 1 to 6, wherein the drain plug is made of an iron-based alloy. A boss is provided between a wall defining the oil passage and a wall defining the oil storage portion, the female screw portion and a relay hole connecting the female thread and the oil storage portion. The internal combustion engine according to any one of claims 1 to 7.

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