JP2017082642A - Lubrication structure for internal combustion engine, and motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify oil passages from a main gallery to bearings for a balancer shaft.SOLUTION: A lubrication structure for an internal combustion engine supplies oil to a bearing (104) for a balancer shaft (54) which is arranged on a crankcase in parallel to a crankshaft (41). In the crankcase, there are provided a main gallery (62) for distributing the oil to each part of the internal combustion engine, oil passages (101a, 101b) for supplying the oil from the main gallery to bearings (102a-102c) for the crankshaft, and oil passages (103a, 103b) for supplying the oil passing through the bearings for the crankshaft to bearings (104a, 104b) for the balancer shaft.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a lubricating structure for an internal combustion engine that supplies oil to each part of the internal combustion engine and a motorcycle.

  In general, in an internal combustion engine lubrication structure, oil is pumped up from an oil pan by an oil pump and supplied to each part of the internal combustion engine through an oil passage branched at a main gallery. As this type of internal combustion engine lubrication structure, there is known a structure in which an oil passage toward the crankshaft and an oil passage toward various speed change shafts are separated (for example, see Patent Document 1). In the internal combustion engine described in Patent Document 1, an oil passage from the main gallery to various transmission shafts is branched in the middle, and oil is supplied to the bearing of the balancer shaft at the upper part of the crankcase through the branched oil passage.

JP-A-2015-090146

  In the lubricating structure of the internal combustion engine of Patent Document 1, the oil passage extends from the main gallery at the lower part of the crankcase toward the bearing of the balancer shaft at the upper part of the crankcase. Since a crankshaft and a transmission shaft are disposed between the main gallery and the balancer shaft, forming the oil passage so as to avoid them complicates the oil passage. For this reason, the oil passage becomes longer, the pressure loss due to the passage resistance increases, and the hydraulic follow-up performance due to crank rotation fluctuations deteriorates. Furthermore, when an oil passage is formed by intersecting a plurality of pipes, the weight of the crankcase increases and burrs are generated at the intersecting portions.

  The present invention has been made in view of this point, and an object of the present invention is to provide a lubricating structure for an internal combustion engine and a motorcycle that can simplify an oil passage from a main gallery to a bearing of a balancer shaft.

  The lubrication structure for an internal combustion engine of the present invention is a lubrication structure for an internal combustion engine that supplies oil to a bearing of a balancer shaft that is disposed in parallel to the crankshaft in the crankcase. A main gallery that distributes oil to the first shaft, a first oil passage that supplies oil from the main gallery to the bearing of the crankshaft, and a second that supplies oil that has passed through the bearing of the crankshaft to the bearing of the balancer shaft. The oil passage is formed.

  According to this configuration, the oil is supplied from the main gallery to the bearing of the crankshaft through the first oil passage, and further, the oil is supplied to the bearing of the balancer shaft through the second oil passage. Oil is sent to the balancer shaft bearing partway through a first oil passage common to the crankshaft bearing. Therefore, the oil passage from the main gallery toward the balancer shaft can be simplified. Since the oil passage can be shortened, pressure loss due to flow path resistance can be reduced, and hydraulic follow-up performance due to crank rotation fluctuation can be improved. Further, since the first and second oil passages are formed in the crankcase, the crankcase can be reduced in weight and a deburring operation is required as compared with a configuration in which a new pipe is provided to form the oil passage. There is nothing.

  In the lubricating structure for an internal combustion engine of the present invention, the second oil passage is formed linearly. According to this configuration, the processing of the second oil passage can be facilitated. Further, the second oil passage can be formed shorter.

  In the internal combustion engine lubrication structure of the present invention, the balancer shaft is disposed below the crankshaft. According to this configuration, the oil can be supplied from the bearing of the crankshaft through the second oil passage to the bearing of the balancer shaft by extending the second oil passage in the vertical direction.

  In the lubricating structure for an internal combustion engine according to the present invention, the crankcase includes an upper case and a lower case, and the first oil passage and the second oil passage are formed in the lower case. According to this configuration, since the first and second oil passages are formed in the same lower case, the oil passage can be further simplified.

  In the lubricating structure for an internal combustion engine of the present invention, the balancer shaft is a lower balancer shaft disposed below the crankshaft, and the main gallery is formed in front of the lower balancer shaft in the crankcase. According to this configuration, the front and rear width of the crankcase can be reduced compared to a configuration in which the balancer shaft is disposed before and after the crankshaft in the crankcase. Further, the arrangement of the lower balancer shaft does not interfere with the main gallery.

  In the lubricating structure for an internal combustion engine of the present invention, a drive shaft of a transmission is disposed in the crankcase in parallel with the crankshaft, and the crankcase is branched from the middle of the second oil passage to the driveshaft. A third oil passage for supplying oil is formed. According to this structure, oil can be sent to the drive shaft halfway through the first and second oil passages common to the bearings of the crankshaft and the balancer shaft. Therefore, the oil passage can be simplified as compared with a configuration in which an oil passage that directly connects the main gallery and the drive shaft bearing is formed.

  The motorcycle according to the present invention includes the lubricating structure for the internal combustion engine. According to this configuration, the oil passage from the main gallery of the motorcycle crankcase to the bearing of the balancer shaft can be simplified.

  According to the lubrication structure for an internal combustion engine of the present invention, oil is sent to the balancer shaft bearing partway through the first oil passage common to the crankshaft bearing. Therefore, the oil passage from the main gallery to the bearing of the balancer shaft can be simplified.

It is a perspective view of the internal combustion engine of this Embodiment. It is a right view of the crankcase of this Embodiment. It is a side view which shows the shaft arrangement | positioning which concerns on this Embodiment. It is a block diagram which shows the lubrication path | route of the internal combustion engine of this Embodiment. It is a front view of the crankcase of this Embodiment. It is sectional drawing which cut | disconnected FIG. 5 by the AA line. It is a perspective view of the upper case and lower case which concern on this Embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings. In the following, an example in which the lubricating structure of the internal combustion engine is applied to a motorcycle will be described. FIG. 1 is a perspective view of the internal combustion engine of the present embodiment. FIG. 2 is a right side view of the crankcase of the present embodiment. FIG. 3 is a side view showing the arrangement of the shafts of the present embodiment. In FIG. 2, for convenience of explanation, the countershaft and the clutch are indicated by a two-dot chain line, and the front balancer shaft and the drive shaft in the crankcase are indicated by a broken line.

  As shown in FIG. 1, the internal combustion engine 1 is a parallel two-cylinder engine and is configured by disposing a cylinder 10 in a crankcase 21. The cylinder 10 is configured by attaching a cylinder head 12 and a head cover 13 to a cylinder block 11 disposed on a crankcase 21. An oil pan 22 for storing oil for lubrication and cooling is attached to the lower portion of the crankcase 21. A generator cover 23 that forms a generator chamber is attached to the left side of the crankcase 21. An oil filter 25 and an oil cooler 26 are attached to the front portion of the crankcase 21.

  As shown in FIG. 2, the crankcase 21 has a vertically divided structure including an upper case 27 and a lower case 28, and the right space 31 of the crankcase 21 is opened to the outside by removing a clutch cover (not shown). doing. The right space 31 of the crankcase 21 is partitioned from the crank chamber inside the case, the transmission chamber, and the like by the side walls of the upper case 27 and the lower case 28, and surrounded by the peripheral wall 32 protruding from the side walls of the upper case 27 and the lower case 28. Space. The right space 31 of the crankcase 21 is partially visible from the outside with a mating surface 33 with the clutch cover formed on the peripheral wall 32 as an opening.

  On the side wall (journal wall) of the crankcase 21, three main axes of the crankshaft 41, the countershaft 47, and the drive shaft 49 are arranged in a triangle in parallel. The crankshaft 41 is housed in a crank chamber inside the case and is rotatably supported by the mating surface 34 of the upper case 27 and the lower case 28. The countershaft 47 is accommodated in a mission chamber inside the case, and is rotatably supported on the side wall of the upper case 27 behind the crankshaft 41. The drive shaft 49 is accommodated in a mission chamber inside the case, and is supported by the mating surface 34 of the upper case 27 and the lower case 28 so as to be rotatable behind the counter shaft 47.

  A front balancer shaft 51 is disposed in front of the crankshaft 41, and a lower balancer shaft 54 is disposed below the crankshaft 41. The front balancer shaft 51 is accommodated in a front balancer chamber (not shown) and is rotatably supported by the mating surface 34 of the upper case 27 and the lower case 28. The lower balancer shaft 54 is rotatably supported by a mating surface 35 (see FIG. 6) between the lower case 28 and the balancer housing 29 by attaching the balancer housing 29 to the lower case 28. By attaching / detaching the balancer housing 29 to / from the lower case 28, the lower balancer shaft 54 is removed to enable switching between the 1-axis balancer and the 2-axis balancer.

  In the right space 31 of the crankcase 21, there are a primary drive gear 42 for the crankshaft 41, a primary driven gear 48 for the countershaft 47, a front balancer driven gear 52 for the front balancer shaft 51, and a lower balancer driven gear 55 for the lower balancer shaft 54. Contained. The primary drive gear 42 meshes with a primary driven gear 48, a front balancer driven gear 52, and a lower balancer driven gear 55. Thus, by driving three types of gears with a single gear, it is not necessary to cut gears separately on the crankshaft 41, and the overall length of the crankshaft 41 is shortened.

  Further, the right space 31 of the crankcase 21 is opened to the outside with the mating surface 33 with the clutch cover as an opening as described above. The primary drive gear 42 is exposed to the outside from the crankcase 21 except for a part, and the clutch 57 and the primary driven gear 48 are entirely exposed to the outside. Further, the front balancer driven gear 52 is hidden inside the crankcase 21, and the lower balancer driven gear 55 is exposed to the outside from the crankcase 21 except for a part thereof. Thus, the gears are easily exposed to each other (phase alignment) by exposing the gears to the outside from the right space 31.

  As shown in FIG. 3, the crankshaft 41 is configured by connecting a crank web 43 with a crankpin (not shown) and a crank journal (not shown). A piston 45 is connected to the crank pin via a connecting rod 44, and the reciprocating motion of the piston 45 is converted into the rotational motion of the crank shaft 41. The rotation of the crankshaft 41 is transmitted to the countershaft 47 via the primary drive gear 42 and the primary driven gear 48. The rotation of the counter shaft 47 is transmitted to the drive shaft 49 at a predetermined gear ratio according to a combination of transmission gears (not shown).

  The rotation of the crankshaft 41 is transmitted to the front balancer shaft 51 via the primary drive gear 42 and the front balancer driven gear 52, and is transmitted to the lower balancer shaft 54 via the primary drive gear 42 and the lower balancer driven gear 55. The Periodic vibration generated in the crankshaft 41 is canceled out by the front balancer shaft 51 and the lower balancer shaft 54. With the connecting rod 44 at the top, the lower balancer shaft 54 at the bottom, the front balancer shaft 51 at the front, and the countershaft 47 at the rear, with the crankshaft 41 as the center, a space in the crankcase 21 (see FIG. 2). Is effectively used.

  In the crankcase 21 configured in this way, the lower balancer shaft 54 is disposed below the crankshaft 41, so that the front-rear width of the crankcase 21 can be increased compared to the configuration in which the balancer shaft is disposed before and after the crankcase 21. It can be made smaller and the mass can be concentrated. Further, since the main gallery 62 (see FIG. 2) is formed in front of the lower balancer shaft 54, the arrangement of the lower balancer shaft 54 is prevented from interfering with the main gallery 62. In this case, since the configuration differs from the configuration in which the main gallery is arranged directly below the crankshaft as in a normal crankcase, the lubrication path for each part of the internal combustion engine 1 must be changed.

  In particular, a lubrication path for the crankcase 21 specialized for the biaxial balancer structure in which the balancer shafts 52 and 54 can be disposed in front and below the crankshaft 41 is required. In the present embodiment, an oil passage 103 extending from the bearing 102 of the crankshaft 41 toward the bearing 104 of the lower balancer shaft 54 is formed downstream of the oil passage 101 extending from the main gallery 62 toward the bearing 102 of the crankshaft 41 ( (See FIG. 6). Since oil is sent to the bearing 104 of the lower balancer shaft 54 halfway through an oil passage common to the bearing 102 of the crankshaft 41, the oil passage can be simplified.

  Hereinafter, the lubrication path of the internal combustion engine formed in the crankcase will be described with reference to FIG. FIG. 4 is a block diagram showing a lubrication path of the internal combustion engine of the present embodiment.

  As shown in FIG. 4, oil is stored in an oil pan 22 below the crankcase 21 (see FIG. 1). The oil in the oil pan 22 is sucked from the strainer by the oil pump 61 driven by the counter shaft 47. The oil sucked by the strainer is sent to the oil filter 25 by the oil pump 61. The oil in the oil filter 25 is sent to the oil cooler 26 by the oil pump 61 and then sent to the main gallery 62. At this time, in the oil filter 25, fine foreign matters in the oil are removed by the filter, and the oil is cooled in the oil cooler 26.

  The oil filter 25 and the oil cooler 26 are disposed on the front surface of the crankcase 21 (see FIG. 5). On the installation surface of the oil filter 25, an inlet 64 connected to the oil pump 61 and an outlet 65 connected to the oil cooler 26 are formed (see FIG. 5). The inlet 64 of the oil filter 25 is formed below the center, and the outlet 65 of the oil filter 25 is formed in the center. On the installation surface of the oil cooler 26, an inlet 67 connected to the oil filter 25 and an outlet 68 connected to the main gallery 62 are formed (see FIG. 5). The inlet 67 of the oil cooler 26 is formed at the center, and the outlet 68 of the oil cooler 26 is formed above the center.

  The oil in the main gallery 62 passes through the oil passages 72a-72c in the right, middle, and left journal walls 71a-71c (see FIG. 7) of the lower case 28, and the bearings 73a- of the front balancer shaft 51 respectively. 73c. The oil in the bearing 73a on the right side of the front balancer shaft 51 is supplied to the sub gallery 76 through the oil passage 75a in the journal wall (not shown) on the right side of the upper case 27. The oil in the sub gallery 76 is supplied to the piston jet 77 and used for cooling the piston 45 (see FIG. 2). Further, the oil in the sub gallery 76 is supplied to a bearing 78 of a turboshaft (not shown) of the supercharger.

  The oil in the bearing 73 c of the left front balancer shaft 51 is supplied to the cylinder head 12 through an oil passage 75 c in the left journal wall (not shown) of the upper case 27. The oil in the cylinder head 12 passes through the inside of a camshaft (not shown), lubricates the contact portion between the cam and the tappet, and the oil return passage 85 and the cam chain chamber 93 (see FIG. 5) formed in the upper case 27. ) Etc., it is returned to the oil pan 22. As described above, the crankcase 21 is formed by dividing the lubrication path from the main gallery 62 to the sub gallery 76 and the lubrication path from the main gallery 62 to the cylinder head 12.

  The oil in the main gallery 62 passes through the oil passages 101a-101c in the right, middle, and left journal walls 71a-71c (see FIG. 7) of the lower case 28, and the bearings 102a of the crankshaft 41 respectively. -102c. The oil in the bearings 102a and 102b at the right and middle of the crankshaft 41 is supplied to the bearings 104a and 104b of the lower balancer shaft 54 through the oil passages 103a and 103b in the journal walls 71a and 71b. The oil passage 103 a on the right side branches off in the middle, and oil is supplied to the drive shaft 49 through the oil passage 105. The oil in the bearing 102c on the left side of the crankshaft 41 is supplied to the countershaft 47 through an oil groove on the journal wall 71c.

  As described above, the crankcase 21 is formed by dividing the lubrication path from the main gallery 62 to the bearings 73a to 73c of the front balancer shaft 51 and the lubrication path from the main gallery 62 to the bearings 102a to 102c of the crankshaft 41. Has been. In addition, oil is supplied to the sub gallery 76 and the cylinder head 12 through the lubrication path of the bearings 73 a and 73 c of the front balancer shaft 51. Oil is supplied to the bearings 104a and 104b, the counter shaft 47, and the drive shaft 49 of the lower balancer shaft 54 through the lubrication path of the bearings 102a to 102c of the crankshaft 41.

  Hereinafter, the lubricating structure of the internal combustion engine will be described in detail. The lubrication path of the lower balancer shaft will be described with reference to FIGS. FIG. 5 is a front view of the crankcase of the present embodiment. 6 is a cross-sectional view of FIG. 5 taken along line AA. FIG. 7 is a perspective view of the upper case and the lower case of the present embodiment. In FIG. 6, for convenience of explanation, the tightening bolt and the counter shaft are omitted.

  As shown in FIGS. 5 and 6, the crankcase 21 includes an upper case 27 and a lower case 28 that are vertically divided, and a balancer housing 29 is attached to the lower case 28 below the crankshaft 41. A common fastening bolt (not shown) is inserted into the upper case 27, the lower case 28, and the balancer housing 29, and a mating surface 34 between the upper case 27 and the lower case 28, and a mating surface 35 between the lower case 28 and the balancer housing 29. It is tightened with a tightening bolt. A front balancer shaft 51, a crankshaft 41, and a drive shaft 49 are supported on the mating surface 34 of the upper case 27 and the lower case 28.

  A counter shaft 47 (see FIG. 3) is supported on the side surface of the upper case 27, and a lower balancer shaft 54 is supported on the mating surface 35 of the lower case 28 and the balancer housing 29. That is, in the crankcase 21, the front balancer shaft 51 is disposed in front of the crankshaft 41, and the lower balancer shaft 54 is disposed below the crankshaft 41. Further, a counter shaft 47 and a drive shaft 49 are disposed behind the crankshaft 41. The lower case 28 of the crankcase 21 is formed with a main gallery 62 that distributes oil to each part of the internal combustion engine 1 in front of the lower balancer shaft 54.

  The main gallery 62 is formed at an obliquely lower front of the crankshaft 41 so as to avoid the lower balancer shaft 54 that is positioned directly below the crankshaft 41. The main gallery 62 is linearly formed below the front balancer shaft 51 in the left-right direction of the lower case 28 (direction perpendicular to the paper surface in FIG. 6). The upper case 27 is formed with a sub gallery 76 that supplies oil to each part of the internal combustion engine 1 obliquely in front of the crankshaft 41 (see FIG. 7). The sub gallery 76 is formed in parallel with the main gallery 62 above the front balancer shaft 51.

  As shown in FIGS. 6 and 7, the lower case 28 is formed with oil passages 101a-101c for supplying oil from the main gallery 62 to the bearings 102a-102c of the crankshaft 41 (bearings 102b, 102c, oil (Refer to FIG. 4 for the passages 101b and 101c). The oil passages 101 a to 101 c extend obliquely from the main gallery 62 to the bearing installation surface 106 of the crankshaft 41. At this time, the oil passages 101a to 101c penetrate the bolt holes 95 of the fastening bolts. The bolt hole 95 has a larger diameter than the shaft portion of the fastening bolt, and a gap between the bolt hole 95 and the shaft portion of the fastening bolt is a passage for oil. By extending the oil passages 101a-101c linearly without avoiding the bolt holes 95, the oil passages 101a-101c can be shortened.

  The lower case 28 is formed with oil passages 103a and 103b for supplying oil that has passed through the right bearings 102a and 102b on the right side of the crankshaft 41 to the bearings 104a and 104b of the lower balancer shaft 54. The oil passages 103 a and 103 b extend directly from the bearing installation surface 106 of the crankshaft 41 to the bearing installation surface 111 of the lower balancer shaft 54. Since the oil passages 103a and 103b are linearly formed in the vertical direction, the processing of the oil passages 103a and 103b can be facilitated, and the oil passages 103a and 103b can be shortened.

  Further, since the oil passages 101a to 101c and the oil passages 103a and 103b are formed in the same lower case 28, the oil passage can be simplified. Oil grooves 107a to 107c (see FIG. 7) are formed in the bearing installation surface 106 of the crankshaft 41. The right and middle oil grooves 107a and 107b serve as oil passages connecting the oil passages 101a and 101b and the oil passages 103a and 103b. The left oil groove 107c extends on the upper surface of the journal wall 71c toward the countershaft 47 (see FIG. 3), and serves as oil for supplying oil that has passed through the bearing 102c of the crankshaft 41 to the countershaft 47. It is a road.

  Further, the lower case 28 is formed with an oil passage 105 that branches from the middle of the right oil passage 103 a and supplies the oil that has passed through the right bearing 102 a of the crankshaft 41 to the drive shaft 49. The oil passage 105 extends obliquely from the middle of the oil passage 103 a to the mating surface 34 of the upper case 27 and the lower case 28. At this time, the oil passage 105 penetrates the bolt hole 95 of the fastening bolt, and the gap between the bolt hole 95 and the shaft portion of the fastening bolt is a passage for oil as described above. By extending the oil passage 105 linearly without avoiding the bolt holes 95, the oil passage 105 can be shortened.

  Since the oil passage 105 extends obliquely, the oil passage 105 toward the drive shaft 49 can be shortened. An oil groove 108 (see FIG. 7) extending from the outlet of the oil passage 105 toward the drive shaft 49 is formed on the upper surface (matching surface 34) of the journal wall 71a. Since the oil passages 101a, 103a, 105 and the oil groove 108 are formed in the journal wall 71a that supports the right end of the crankshaft 41, they are linearly arranged from the main gallery 62 toward the right end of the drive shaft 49 in a top view. Has been. Therefore, the oil passage from the main gallery 62 toward the drive shaft 49 can be simplified.

  In addition, the oil passage 101a and the oil passage 105 have the same inclination angle with respect to the mating surface 34 of the upper case 27 and the lower case 28, and the oil passage 101a and the oil passage 105 have the same passage diameter. Thus, the oil passages 101a and 105 can be formed by processing the crankcase 21 from the same direction with a processing tool having the same diameter, and the processing cost can be reduced. The outlet of the oil passage 105 is an orifice installation portion 109 in which an orifice (not shown) can be installed. By installing the orifice in the orifice installing portion 109, the oil flow rate from the oil passage 105 toward the drive shaft 49 can be suppressed even if the oil passage 105 is formed to have the same diameter as the oil passage 101a.

  In this manner, oil is sent from the main gallery 62 to the bearings 102a to 102c of the crankshaft 41, and the oil of the bearings 102a and 102b is supplied to the bearings 104a and 104b of the lower balancer shaft 54 through the oil passages 103a and 103b. . The oil in the bearing 102a is supplied to the drive shaft 49 through the oil passage 105 branched in the middle of the oil passage 103a. The crankshaft 41 and the lower balancer shaft 54 serve as part of the oil passages 101a and 101b, and the lower balancer shaft 54 and the drive shaft 49 serve as part of the oil passage 103a. Therefore, it is possible to simplify the lubrication path in the crankcase 21 and shorten the overall length of the oil passage.

  As described above, according to the present embodiment, oil is supplied from the main gallery 62 to the bearings 102a to 102c of the crankshaft 41 through the oil passages 101a to 101c, and is further passed through the oil passages 103a and 103b to the lower balancer. Oil is supplied to the bearings 104a and 104b of the shaft 54. Oil is sent to the bearings 104a and 104b of the lower balancer shaft 54 halfway through oil passages 101a and 101b common to the bearings 102a and 102b of the crankshaft 41. Therefore, the oil passage from the main gallery 62 toward the lower balancer shaft 54 can be simplified. Since the oil passage can be shortened, pressure loss due to flow path resistance can be reduced, and hydraulic follow-up performance due to crank rotation fluctuation can be improved. Furthermore, since the oil passage is formed in the crankcase 21, the crankcase 21 can be reduced in weight and deburring work does not occur as compared with a configuration in which a new pipe is provided to form the oil passage.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above-described embodiment, the oil passage 103 is formed in the right and middle journal walls 71a and 71b. However, the present invention is not limited to this configuration. The oil passage 103 may be formed in the journal wall 71 on which the lower balancer shaft 54 is supported. For example, when the lower balancer shaft 54 is supported by the middle and left journal walls 71b and 71c, the oil passage 103 is formed in the journal walls 71b and 71c.

  Further, in the above-described embodiment, the configuration is such that the two front balancer shafts 51 and the lower balancer shaft 54 are disposed in the crankcase 21, but the present invention is not limited to this configuration. The crankcase 21 may be provided with at least one balancer shaft.

  In the above-described embodiment, the front balancer shaft 51 is arranged on the mating surface 34 of the upper case 27 and the lower case 28. However, the present invention is not limited to this configuration. The front balancer shaft 51 may be disposed in either the upper case 27 or the lower case 28.

  In the above-described embodiment, the crankcase 21 is configured by the upper case 27 and the lower case 28 having a vertically split structure. However, the present invention is not limited to this configuration. The crankcase 21 may be composed of a left case and a right case having a left-right split structure.

  In the above-described embodiment, the oil passage 103 is formed in a linear shape, but is not limited to this configuration. The oil passage 103 only needs to be formed so that oil that has passed through the bearing 102 of the crankshaft 41 can be supplied to the lower balancer shaft 54, and may be formed in an arc shape, for example.

  In the above-described embodiment, the lower balancer shaft 54 is disposed on the mating surface 35 of the lower case 28 and the balancer housing 29. However, the present invention is not limited to this configuration. The lower balancer shaft 54 may be disposed in the lower case 28. In this case, the balancer housing 29 may not be provided.

  In the above-described embodiment, the lower balancer shaft 54 is disposed below the crankshaft 41. However, the present invention is not limited to this configuration. Instead of the lower balancer shaft 54, a rear balancer shaft may be arranged behind the crankshaft 41.

  In the above-described embodiment, the oil passages 101 and 103 are formed in the same lower case 28. However, the present invention is not limited to this configuration. For example, the oil passages 101 and 103 may be formed across the upper case 27 and the lower case 28.

  In the above-described embodiment, the oil is supplied to the drive shaft 49 through the oil passage 105 branched from the middle of the oil passage 103a. However, the present invention is not limited to this configuration. Oil may be supplied to the drive shaft 49 through another lubrication path.

  In the above-described embodiment, the oil groove 107 is formed on the bearing installation surface 106 of the journal wall 71 so that the bearing 102 of the crankshaft 41 passes through the oil. However, the present invention is not limited to this configuration. Any structure may be used as long as oil can pass through the bearing 102 of the crankshaft 41. For example, an oil groove may be formed in the bearing 102, or an oil groove may be formed in the crankshaft 41.

  As described above, the present invention has an effect that the oil passage from the main gallery to the bearing of the balancer shaft can be simplified, and is particularly useful for a lubricating structure of an internal combustion engine of a motorcycle.

1 Internal combustion engine 21 Crank case 27 Upper case 28 Lower case 41 Crankshaft 49 Drive shaft 51 Front balancer shaft 54 Lower balancer shaft (balancer shaft)
62 Main gallery 73 Front balancer shaft bearing 101 Oil passage (first oil passage)
102 Crankshaft bearing 103 Oil passage (second oil passage)
104 Lower balancer shaft bearing 105 Oil passage (third oil passage)
109 Orifice installation section

Claims (7)

A lubricating structure for an internal combustion engine that supplies oil to a bearing of a balancer shaft arranged in parallel to the crankshaft in a crankcase,
A main gallery that distributes oil to each part of the internal combustion engine, a first oil passage that supplies oil from the main gallery to the bearing of the crankshaft, and oil that has passed through the bearing of the crankshaft A lubricating structure for an internal combustion engine, characterized in that a second oil passage for supplying to the bearing of the balancer shaft is formed.   2. The lubricating structure for an internal combustion engine according to claim 1, wherein the second oil passage is formed linearly.   The lubricating structure for an internal combustion engine according to claim 1, wherein the balancer shaft is disposed below the crankshaft. The crankcase consists of an upper case and a lower case that are vertically divided,
The internal combustion engine lubrication structure according to any one of claims 1 to 3, wherein the first oil passage and the second oil passage are formed in the lower case. The balancer shaft is a lower balancer shaft disposed below the crankshaft;
The internal combustion engine lubrication structure according to any one of claims 1 to 4, wherein the main gallery is formed in front of the lower balancer shaft in the crankcase. A drive shaft of a transmission is arranged in the crankcase in parallel with the crankshaft,
The third oil passage is formed in the crankcase so as to branch from the middle of the second oil passage and supply oil to the drive shaft. The internal combustion engine lubricating structure described.   A motorcycle comprising the lubricating structure for an internal combustion engine according to any one of claims 1 to 6.

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