Title of Invention

"OIL PUMP APPARATUS OF INTERNAL COMBUSTION ENGINE"

Abstract

[Object] To provide an oil pump apparatus of an internal combustion engine, which is capable of making easy a mounting work for a base plate, reducing steps of machining a mounting surface of the base plate, and improving a cooling efficiency of the internal combustion engine. [Solving Means] An oil pump apparatus of an internal combustion engine of a type in which an oil pump 140 is provided in a crank case opposite to a belt type continuously variable transmission 35 is so configurated that the crank case has, at a portion where side portions of the oil pump 140 and its neighborhood are disposed, an opening having such an area being as small as not to permit penetration of a crank shaft 40, and the opening 130 is covered with a base plate 131 of the oil pump 140 to house the oil pump 140 in the crank case.

Full Text

[Detailed Description of the Invention] [0001] [Technical Field of the Invention] The present invention relates to an oil pump apparatus disposed in a crank case of an internal combustion engine of a type including a belt-type continuously variable transmission. [0002] [Related Art] In an internal combustion engine of a type including a belt-type continuously variable transmission, an oil pump driven by a crank shaft just as the belt-type continuously variable transmission is generally disposed in a crank case opposite to the belt-type continuously variable transmission. [0003] An example of the internal combustion engine having the above configuration, which is described in Japanese Patent Laid-open No. Hei 4-81525, will be described with reference to Fig. 7. Fig. 7 is a right side view showing a four-cycle internal combustion engine 01 in which an AC generator and the like are omitted. In the four-cycle internal combustion engine 01, a cylinder block 03 projects forward from a crank case 02 in a state being largely tilted forward therefrom, and a cylinder head 04 is connected to an end portion of the cylinder block 03. [0004] The crank case 02 has, in a right side surface, a large circular opening 05 permitting penetration of a crank shaft 05 disposed in the horizontal direction (right and left) in the crank case 02. The circular opening 05 is blocked with a large disk shaped base plate 06 having a through-hole permitting penetration of the crank shaft 05 therethrough. An AC generator is provided outside the base plate 06. [0005] An oil pump 08 is housed in the crank case 02 in the state being covered with the base plate 06. A pump shaft 09 is rotatably supported at a position under the crank shaft 05 in such a manner as to be in parallel to the crank shaft 05. The oil pump 08 is driven by meshing of a drive gear 010 fitted around the crank shaft 05 with a driven gear 011 fitted around the pump shaft 09. [0006] The oil pump 08 is driven to supply oil to various necessary portions. For example, oil is supplied to a valve system, by driving of the oil pump 08, through an oil cleaner 012 and an oil pipe 013. The oil pipe 013 extends forward, downward from the cylinder block 03 and is connected at its end portion to the cylinder head 04, to be thus communicated to a valve system chamber 014. [0007] [Problem to be Solved by the Invention] In the related art oil pump apparatus, the crank case 02 has at the right side surface the circular opening 05 having an area being as large as to permit penetration of the crank shaft 05 and the circular opening 05 is blocked with the large sized base plate 06 so as to house the oil pump 08 in the crank case 02. As a result, the maintenance characteristic of the base plate 06 is poor, that is, the base plate 06 is not easy to be mounted/ dismounted because the base plate 06 has a large size and also it allows penetration of the crank shaft 05-therethrough. Moreover, since the large-sized circular opening 05 is blocked with the large-sized base plate 06, the number of steps of machining a mounting surface extending around a peripheral edge of the circular opening 05 becomes large. [0008] Additionally, a rib extending from the crank case and covering the outside of an outer rotor of an AC generator cannot be sufficiently formed around the large-sized base plate 06 by obstruction of the large-sized base plate 06, and consequently there occurs a relatively large loss in cooling wind supplied to the internal combustion engine from a cooling fan provided on the outer rotor of the AC generator, resulting in the reduced cooling efficiency of the internal combustion engine. [0009] In view of the foregoing, the present invention has been made, and an object of the present invention is to provide an oil pump apparatus of an internal combustion engine, which is capable of making easy a mounting work for a base plate, reducing the number of steps of machining a mounting surface of the base plate, and improving a cooling efficiency of the internal combustion engine. [0010] [Means for Solving the Problem] To achieve the above object, according to an invention described in claim 1, there is provided an oil pump apparatus of an internal combustion engine of a type including an oil pump in a crank case opposite to a belt-type continuously variable transmission, characterized in that the crank case has, at a portion where side portions of the oil pump and its neighborhood are positioned, an opening having an area being as small as not to permit penetratibn of a crank shaft therethrough; and the opening is covered with a base plate of the oil pump so as to house the oil pump in the crank case. [0011] With this configuration, the crank case opposite to the belt-type continuously variable transmission has, at a portion where side portions of an oil pump and its neighborhood are positioned, an opening having an area being as small as not to penetration of the crank shaft, and accordingly, the area of the opening is smaller than that of the conventional opening, and the base plate covering the opening becomes smaller and also it does not permit penetration of the crank shaft. As a result, it is possible to significantly easily mount the base plate. [0012] With this configuration, the small area of the opening formed in the crank case is also effective to reduce the number of steps of machining a mounting surface extending around a peripheral edge of the opening. Additionally, since the base plate has a small size, a rib extending from the crank case and covering the outside of an outer rotor of an AC generator can be relatively freely formed around the base plate without obstruction of the base plate. This makes it possible to eliminate a loss in cooling wind supplied to the internal combustion engine from a cooling fan provided on the outer rotor of the AC generator, and hence to improve a cooling efficiency of the internal combustion engine. [0013] According to an invention described in claim 2, in addition to the configuration of the invention described in claim 1, a pulser for detecting an action of a reluctor provided on an outer rotor of an AC generator provided at an end portion of the crank shaft, is projectingly provided on the base plate. With this configuration, the pulser is disposed to fill up a portion of the rib which cannot be formed by obstruction of the base plate, so that it is possible to further reduce the loss in cooling wind by making use of the pulser disposed to fill up the discontinuous portion of the rib, and hence to further improve the cooling efficiency of the internal combustion engine. [0014] [Embodiment of the Invention] Hereinafter, one embodiment of the present invention will be described with reference to Figs. 1 to 6. [Brief Description of the Drawings] [Fig. 1] A side view showing an entire configuration of a scooter type motorcycle according to one embodiment of the present invention. [Fig. 2] A sectional view taken on line II-II of Fig. 1, showing an internal combustion engine of the scooter type motorcycle. [Fig. 3] A sectional view taken on line Ill-Ill of Fig. 2. [Fig. 4] A sectional view taken on line IV-IV of Fig. 3. [Fig. 5] A right side view of the internal combustion engine excluding an AC generator and a base plate. [Fig. 6] A sectional view taken on line VI-VI of Fig. 5. [Fig. 7] A right side view of a related art four-cycle internal combustion engine excluding an AC generator and the like. Fig. 1 is a side view of a scooter type motorcycle including a unit swing type internal combustion engine according to the present invention. A body front portion 2 is connected to a body rear portion 3 through a low floor portion 4, and a body frame forming a skeleton of the body is generally composed of a down tube 6 and main pipes 7. [0015] Specifically, the down tube 6 extends downward from a steering head 5 of the body front portion 2, curving in the horizontal direction at its lower end, and extends rearward along the lower side the floor portion 4. The down tube 6 is connected at its rear end to a pair of the right and left main pipes 7. The main pipes 7 are raised obliquely, rearward from the connection portion, curving in the horizontal direction at a specified height, and extends rearward in the horizontal state. [0016] A fuel tank and a containing box are supported by the main pipes 7, and a seat 8 is disposed over the main pipes 7. On the other hand, in the body front portion 2, a handlebar 11 is rotatably supported by an upper end portion of the steering head 5, and a front wheel 13 is rotatably supported by a lower end portion of a front fork 12 extending downward from the steering head 5. [0017] Brackets 15 are each projectingly provided at lower ends of rising portions of the main pipes 7, and a swing unit 17 is rockably connected to and supported by the brackets 15 through link members 16. [0018] The swing unit 17 has at its front portion a single cylinder/four-cycle internal combustion engine 30 in such a posture that a cylinder block 32 projects forward while being largely tilted up to an approximately horizontal state, and an end portion of each hanger bracket 18 projecting forward from a lower end of a portion, corresponding to a crank case, of the unit swing case 31 is connected to the link member 16 through a pivot 19. [0019] A belt-type continuously variable transmission 35 is disposed rearward from the internal combustion engine 30, and a rear wheel 21 is rotatably supported by a reduction gear mechanism 38 provided on a rear portion of the belt-type continuously variable transmission 35. A rear cushion 22 is interposed between an upper end of the reduction gear mechanism 38 and an upper bent portion of the main pipe 7. [0020] A carburetor 24 connected to an intake pipe 23 extending from an upper portion of the cylinder block 33 of the internal combustion engine 30 and an air cleaner 25 connected to the carburetor 24 are disposed on the upper portion of the swing unit 17. On the other hand, a main stand 26 is pivotably mounted on the hanger bracket 18 projectingly formed on the lower portion of the unit swing case 31. A base end of a kick arm 28 is fixed on a kick shaft 27 projecting from a transmission case cover 36 of the belt-type continuously variable transmission 35, and a kick pedal 29 is provided on the leading end of the kick arm 28. [0021] With respect to the body front portion 2, front and rear sides thereof are covered with a front cover 9a and a rear cover 9b; right and left sides thereof are covered with a front lower cover 9c; and a central portion of the handlebar 11 is covered with a handlebar cover 9d. The floor portion 4 is covered with a side cover 9e, and right and left sides of the body rear portion 3 are covered with a body cover 10a and a tail side cover 10b. [0022] Fig. 2 is a sectional view substantially taken on line II-II of Fig. 1, showing the swing arm 17. The unit swing case 31 is divided into a left unit case 31L and a right unit case 31R. The right unit case 31R is a half of the crank case portion, and the left unit case 31L is composed of a crank case portion 31a positioned on a front side and extending longer in the longitudinal direction, a transmission case portion 31b positioned at the center, and a reduction gear case portion 31c positioned on a rear side. [0023] The left unit case 31L having a left side opened surface covered with a transmission case cover 36, contains the belt-type continuously variable transmission 35. The rear side reduction gear case portion 31c having a right side opened surface covered with a reduction gear case 37, contains the reduction gear mechanism 38. [0024] In the so-called crank case composed of the crank case portion 31a and the right unit case 31R, the crank shaft 40 is rotatably supported by right and left main bearings 41, 41. The crank shaft 40 has right and left extension portions extending in the horizontal direction (right and left), wherein the right extension portion is provided with an AC generator 60 while the left extension portion is provided with a cam chain drive sprocket 55 and a drive pulley 76 of the belt-type continuously variable transmission 35. [0025] In the internal combustion engine 30, a piston 42 reciprocating in a cylinder liner 44 of the cylinder block 32 is connected to a crank pin 40a of the crank shaft 40 by means of a connecting rod 43. The four-cycle internal combustion engine 30 adopts an OHC type valve system, in which a valve mechanism 50 is provided in a cylinder head cover 34, and a cam chain 51 for transmitting a drive power to the valve mechanism 50 is hung between a cam shaft 53 and the crank shaft 40. A cam chain chamber 52 containing the cam chain 51 is provided in such a manner as to be communicated to the crank case portion 31a, the cylinder block 32, and the cylinder head 33. [0026] Specifically, the cam chain 51 in the cam chain chamber 52 is hung between a driven sprocket 54 fitted around a left end of the cam shaft 53 extending in the horizontal direction (right and left) and a drive sprocket 55 fitted around the crank shaft 40. An ignition plug 45 is inserted in the cylinder head 33 in such a manner as to direct from the opposed side of the cam chain chamber 52 to a combustion chamber. [0027] As shown in Fig. 3, the valve mechanism 50 in the cylinder head cover 34 has an intake valve 56 and an exhaust valve 57 respectively arranged on upper and lower sides of the cam shaft 53 because the cylinder projects forward while being largely tilted up to an approximately horizontal state. Rocker arms 59, 59 are rockably mounted on upper and lower rocker shafts 58, 58 respectively, and are rocked by rotation of a cam of the cam shaft 53 to open and close the intake valve 56 and the exhaust valve 57 at a specified timing. [0028] The AC generator 60 provided on the right side surface of the right unit case 31R has a bowl shaped outer rotor 62 and a stator 64 around which a stator coil 65 is wound. The outer rotor 62 is fixed through an ACG boss 61 onto an end portion of the crank shaft 30 projecting from a central cylinder portion 31d of the right unit case 31R, and the stator 64 is fixed onto the central cylinder portion 31d in a state being positioned inside magnets 63 arranged on the inner peripheral surface of the outer rotor 62 in the circumferential direction. [0029] A forcedly air cooling fan 66 is mounted on a right side surface of the outer rotor 62, and the side portion of the fan 66 is covered with a fan cover 67. A fan shroud 68 is connected to the fan cover 67 in such a manner as to cover the outside of the cylinder block 32 and the cylinder head 33. [0030] On the other hand, the cam chain chamber 52 is formed in the crank case portion 31a of the unit swing case 31 in a state being partitioned from the crank chamber by means of the main bearing 41. A left side wall of the cam chain chamber 52 is a partitioning wall 71 partitioning the cam chain chamber 52 from a belt-type continuously variable transmission chamber 70 positioned leftward from the cam chain chamber 52. The partitioning wall 71 has a circular through-hole 71a shaped in a large diameter flat cylinder for allowing the crank shaft 40 to pass therethrough. An annular seal member 72 is press-fitted in the circular through-hole 71a, and the crank shaft 40 passes through a hollow portion of the annular seal member 72. [0031] The drive sprocket 55 is fitted around a portion of the crank shaft 40 positioned between the seal member 72 and the main bearing 41, and the cam chain 51 is wound around the drive sprocket 55. The belt-type continuously variable transmission chamber 70 is water-tightly partitioned from the cam chain chamber 52 by means of the seal member 72 for preventing leakage of oil into the belt-type continuously variable transmission chamber 70. A drive pulley 76 is provided around the crank shaft 40 extending through the seal member 72 in such a manner as to be rotatable together with the crank shaft 40. [0032] The drive pulley 76 is composed of a fixed side half pulley 77 and a movable side half pulley 78. The fixed side half pulley 77 is fixed on a left end portion of the crank shaft 40 through a boss 79, and the movable side half pulley 78 positioned on the right side of the fixed side half pulley 77 is spline-fitted around the crank shaft 40. The movable side half pulley 78 is rotatable together with the crank shaft 40 and slidable in the axial direction to move close to/apart from the fixed side half pulley 77, and a V-belt 75 is held and wound between both the half pulleys 77, 78. [0033] A cam plate 80 is provided on the right side of the movable side half pulley 78 at a fixed position close to the annular seal member 72, and a slide piece 80a provided at an outer peripheral edge is slidably engaged with a cam plate sliding boss portion 78a axially formed at an outer peripheral edge of the movable side half pulley 78. A side surface of the movable side half pulley 78 on the cam plate 80 side is tapered toward the cam plate 80 side, and a dry weight roller 81 is contained inside the taper surface of the movable side half pulley 78 while being held by the cam plate 80. [0034] Accordingly, as a rotational speed of the crank shaft 40 is increased, the dry weight roller 81 held between the movable side half pulley 78 and the cam plate 80 and rotated together therewith is moved in a centrifugal direction by a centrifugal force, so that the movable side half pulley 78 is pressed leftward by the dry weight roller 81 to move close to the fixed side half pulley 77. As a result, the V-belt 75 held between both the half pulleys 77, 78 is moved in the centrifugal direction, to thereby increase the winding diameter of the V-belt. [0035] A driven pulley 86 corresponding to the drive pulley 76, which is provided behind the drive pulley 76, has a fixed side half pulley 87 and a movable side half pulley 88. The fixed side half pulley 87 is fitted around an inner sleeve 89 supported by a reduction gear input shaft 92 of the reduction gear mechanism 38 in such a manner as to be rotatable relative to the reduction gear input shaft 92. The movable side half pulley 88 is fitted around an outer sleeve 90 axially slidably supported by the inner sleeve 89 on the left side of the fixed side half pulley 87. The V-belt 75 is held between both the half pulleys 87, 88. [0036] A centrifugal clutch 91 is provided leftward from the reduction gear input shaft 92 and the inner sleeve 89. When a power (rotational speed) transmitted to the inner sleeve 89 through the V-belt 75 is increased, the centrifugal clutch 91 is turned into an engagement state and the power is transmitted to the reduction gear input shaft 92. The reduction gear mechanism 38 transmits" the power transmitted to the reduction gear input shaft 92 to an output shaft 94 through an intermediate shaft 93 while reducing the rotational speed by gear meshing, and the output shaft 94 rotates the rear wheel 21 through an axle of the rear wheel 21. [0037] A drum brake 95 is provided on a hub portion of the rear wheel 21, and a drum brake arm 97 connected to a brake cable is fitted to the drum brake shaft 96. When the brake cable is pulled, the drum brake arm 97 is rocked to turn the drum brake shaft 96, thereby operating the drum brake 95. [0038] The transmission case cover 36 covering the belt-type continuously variable transmission chamber 70 from the left side covers a range from the drive pulley 76 on the front side to the centrifugal clutch 91 on the rear side, and the kick shaft 27 is supported at a portion slightly forward from the center of the transmission case cover 36 in such a manner as to turnably pass through the transmission case cover 36. A drive helical gear 100 is fitted around an inner end portion of the kick shaft 27, and is biased by a return spring 101. [0039] A sliding shaft 102 is supported on the inner surface of a front portion of the transmission case cover 36 in such a manner as to be coaxial with the crank shaft 40 and to be rotatable and axially slidable. A driven helical gear 103, which is formed around the sliding shaft 102, meshes with the drive helical gear 100, and a rachet wheel 104 is fixed at the right end of the sliding shaft 102. These parts, the driven helical gear 103 and the rachet wheel 104, are entirely biased leftward by a friction spring 105. On the other hand, a rachet 79a opposite to the rachet wheel 105 is formed on a boss 79 on the crank shaft 40 side. The rachet wheel 105 and the rachet 79a can be moved close to/apart from each other by sliding of the sliding shaft 102. [0040] Accordingly, when the kick pedal 29 is depressed and the kick shaft 27 is rotated against the return spring 101 through the kick arm 28, the drive helical gear 100 is rotated together with the kick shaft 27 and the driven helical gear 103 meshing with the drive helical gear 100 is slid rightward against the friction spring 105 while being rotated together with the sliding shaft 102, so that the rachet wheel 105 meshes with the rachet 79a of the boss 79 to forcibly rotate the crank shaft 40, thereby starting the internal combustion engine 30. [0041] On the other hand, with respect to the internal combustion engine, a starter motor 110 is disposed over the crank case portion 31a of the left unit case 31L. As shown in Fig. 4, in the starter motor 110, a pinion 113 wound with a coil 112 of an inner rotor surrounded by a magnet 111 of an outer rotor projects leftward, and it has a gear 113a at its left end portion. [0042] A jumping gear mechanism 115 is provided between the starter motor 110 and the drive pulley 76 with its shaft directing in the horizontal direction in a state being held by the crank case portion 31a and the transmission case cover 36. The pinion gear 113a of the starter motor 110 meshes with an input gear 116 provided on a right side of the jumping gear mechanism 115, and a jumping gear 117 provided on a left side of the jumping mechanism 115 meshes with a starter ring gear 77a formed around an outer peripheral edge of the fixed side half pulley 77 when being jumped leftward. [0043] Accordingly, as the starter motor 110 is driven, the rotation of the pinion 113 is transmitted to the input gear 116 of the jumping gear mechanism 115 and the jumping gear 117 is jumped leftward to mesh with the starter ring gear 77a of the fixed side half pulley 77, so that the fixed side half pulley 77 is rotated together with the crank shaft 40 to start the internal combustion engine 30. In addition, when the starter motor 110 is stopped, the jumping gear 117 is drawn to release the meshing with the starter ring gear 77a. [0044] With respect to the fixed side half pulley 77 formed with the starter ring gear 77a to be meshed with the jumping gear 117, it has a rubber made cooling fan 118 attached by rubber burning on a side surface (left side surface) opposite to the side surface holding the V-belt 75. The belt-type continuously variable transmission 35 is cooled by rotation of the cooling fan 118. [0045] Referring to Figs. 1 and 2, the transmission case cover 36 has a cylindrical suction duct 36a projecting from its front portion, and a cylindrical discharge duct 36b formed at an approximately center position in the longitudinal direction in such a manner as to extend obliquely, vertically along its side wall. An accordion hose 14 is connected at its rear end to the suction duct 36a, extending forward, and is connected at its front end to a discharge cylinder 6b projecting from the bent portion of the down tube 6. [0046] A suction cylinder 6a is projectingly formed in the down tube 6 at a position having a height substantially equal to that of the steering head 5. The suction cylinder 6a is communicated to the discharge cylinder 6b by way of the down tube 6. [0047] Accordingly, when the cooling fan 118 is rotated by rotation of the crank shaft 40 in the belt-type continuously variable transmission chamber 70, air is sucked from the suction cylinder 6a of the down tube 6, passing through the down tube 6, and enters the accordion hose 14 from the discharge cylinder 6b. The air further passes through the suction duct 36a, being sucked in the belt-type continuously variable transmission chamber 70 for cooling the belt-type continuously variable transmission chamber 35, and is discharged to the exterior from the discharge duct 36b. [0048] As described above, the right unit case 31R as a crank case opposite to the left unit case 31L containing the belt-type continuously variable transmission chamber 70 has the central cylinder portion 31d allowing the crank shaft 40 to pass therethrough, the central cylinder portion 31d projecting rightward from the right unit case 31R. The right unit case 31R has also a circular opening 130 formed in such a manner as to be adjacent to the central cylinder portion 31d and to extend slightly obliquely, forward, downward from the central cylinder portion 31d. A circular base plate 131 as a lid member blocks the circular opening 130, to house an oil pump 140 in the right unit case 31R. [0049] Fig. 5 is a right side view of the internal combustion engine 30 excluding the AC generator 60 and the base plate 131. The right unit case 31R has in a side wall two openings, that is, the central cylinder portion 31d and the circular opening 130. A cylindrical rib 132 is projectingly formed on the right unit case 31R coaxially with the crank shaft 40, that is, around the same center as that of the central cylinder portion 31d. The rib 132 has an outside diameter slightly larger than that of the outer rotor 62 of the AC generator 60. An outer peripheral wall 133 is provided outward from the cylindrical rib 132. [0050] A lower portion of the cylindrical rib 132 is lost by the circular opening 130, and the outer peripheral wall 133 is slightly swelled downward by the circular opening 130. In this way, the circular opening 130 does not contain the central cylinder portion 31d as a through-hole for the crank shaft 40, and is formed adjacent to the central cylinder portion 31d. The circular opening 130 has an outside diameter substantially equal to a radius of the outer peripheral wall 133, that is, an outside diameter being as small as to only cover the oil pump 140 contained therein and its neighborhood. [0051] As shown in Fig. 6, the circular base plate 131 for blocking the circular opening 130 is inserted in the circular opening 130 through a seal ring 134, and a flange portion 131a is brought in contact with a mounting surface 130a extending around the peripheral edge of the circular opening 130 and is fixed thereto at front and rear female threaded portions 130b by means of bolts 135. A mounting boss 131b is swelled from an outer surface of the base plate 131, and a pulser 137 is fixed on the mounting boss 131b. [0052] The pulser 137 is an induction coil type pick up sensor, which projects rightward to face to the outer peripheral surface of the outer rotor 62 of the AC generator 60. The pulser 137 detects an action of a reluctor 138 provided on the outer rotor 62 so as to obtain information on crank position and rotational speed. As shown by a two-dot chain line in Fig. 5, the pulser 137 is projectingly provided at the portion of the cylindrical rib 132 lost by the circular opening 130, so that the pulser 137 compensates for the lost portion of the cylindrical rib 132 to form a wall. [0053] Accordingly, air sucked from the center of the fan cover 67 by rotation of the forcedly air cooling fan 66 provided on the right side surface of the outer rotor 62 of the AC generator 60 is introduced in the center substantially without leakage by the wall composed of the cylindrical rib 132 and the pulser 137, and is then guided on the cylinder block 32 side of the internal combustion engine 30 by the fan shroud 68, to thus enhance a cooling efficiency. [0054] On the other hand, the base plate 131 has at the center of the inner surface a cylindrical projection 131c for pressing a driven gear 141 of the oil pump 140 contained in the right unit case 31R. A pump shaft 142 is formed integrally with the driven gear 141, and a drive gear 143 fitted around the crank shaft 40 along the main bearing 41 meshes with the driven gear 141, to transmit the rotation of the crank shaft 40 to the pump shaft 142, thereby driving the oil pump 140. [0055] As shown in Fig. 6, oil remaining in a bottom portion of the crank case portion 31a is sucked in a suction port 14a of the oil pump 140 by way of an oil filter 147, a horizontal oil passage tl, and an approximately vertical oil passage t2, and is discharged from a discharge port 140b, to be thus supplied to each lubricating apparatus. [0056] As described above, the oil pump 140 of the internal combustion engine 30 is disposed in the right unit case 31R opposite to the belt-type continuously variable transmission 35, and the right unit case 31R has the circular opening 130 at a portion where only the oil pump 140 and its neighborhood are disposed, wherein the circular opening 130 has an area being smaller in diameter than the conventional one, that is, being small as not to permit penetration of the crank shaft 40, and also the base plate 131 for blocking the circular opening 130 is smaller in diameter than the conventional one. [0057] Accordingly, the base plate 131 can be significantly easily mounted/dismounted upon maintenance, to thereby improve the maintenance characteristic of the base plate 131. Moreover, since the inside diameter of the circular opening 130 is small, it is possible to reduce steps of machining the mounting surface 130a of the base plate 131 at the peripheral edge of the circular opening 130, and to make easy the machining work. [0058] Additionally, since the circular opening 130 is small in diameter and thereby in area, the lost portion of the cylindrical rib 132 of the circular opening 130 is made small, so that it is possible to reduce a loss in cooling wind supplied to the internal combustion engine from the forcedly air cooling fan 66. Also, in the internal combustion engine 30, the pulser 137 compensates for the lost portion, so that it is possible to further improve the cooling efficiency. [0059] [Effect of the Invention] According to the present invention, a crank case opposite to a belt-type continuously variable transmission has, at a portion where side portions of an oil pump and its neighborhood are positioned, an opening having an area being as small as not to penetration of the crank shaft, and accordingly, the area of the opening is smaller than that of the conventional opening, and the base plate covering the opening becomes smaller and also it does not receive penetration of the crank shaft. As a result, it is possible to significantly easily mount/dismount the base plate, and hence to improve the maintenance characteristic of the base plate. [0060] The small area of the opening formed in the crank case is also effective to reduce the number of steps of machining a mounting surface extending around a peripheral edge of the opening and to make easy the machining work. Additionally, since the base plate has a small size, a rib extending from the crank case and covering the outside of an outer rotor of an AC generator can be relatively freely formed without obstruction of the base plate. This makes it possible to eliminate a loss in cooling wind supplied to the internal combustion engine from a cooling fan provided on the outer rotor of the AC generator, and hence to improve a cooling efficiency of the internal combustion engine. [0061] According to the present invention, a pulser for detecting an action of a reluctor provided on an outer rotor of an AC generator provided at an end portion of the crank shaft is projectingly provided on the base plate, and accordingly the pulser is disposed to fill up a portion of the rib which cannot be formed by obstruction of the base plate. As a result, it is possible to further reduce the loss in cooling wind by making use of the pulser disposed to fill up the discontinuous portion of the rib, and hence to further improve the cooling efficiency of the internal Combustion enoina. [Explanation of Characters] 1: scooter type motorcycle, 2: body front portion, 3: body rear portion, 4: floor portion, 5: steering head, 6: down tube, 7: main pipe, 8: seat, 9a: front cover, 9b: rear cover, 9c: front lower cover, 9d: handlebar cover, 9e: side cover, 10a: body cover, 10b: tail side cover, 11: handlebar, 12: front fork, 13: front wheel, 14: accordion hose, 15: bracket, 16: link member, 17: swing unit, 18: hanger bracket, 19: pivot, 21: rear wheel, 22: rear cushion, 23: intake pipe, 24: carburetor, 25: air cleaner, 26: main stand, 27: kick shaft, 28: kick arm, 29: kick pedal, 30: internal combustion engine, 31: unit swing case, 32: cylinder block, 33: cylinder head, 34: cylinder head cover, 35: belt-type continuously variable transmission, 36: transmission case cover , 37: reduction gear case, 38: reduction gear mechanism, 40: crank shaft, 41: main bearing, 42: piston, 43: connecting rod, 44: cylinder liner, 45: ignition plug, 50: valve system, 51: cam chain, 52: cam chain chamber, 53: cam shaft, 54: driven sprocket, 55: drive sprocket, 56: intake valve, 57: exhaust valve, 58: rocker shaft, 59: rocker arm, 60: AC generator, 61: ACG boss, 62: outer rotor, 63: magnet, 64: stator, 65: stator coil, 66: fan, 67: fan cover, 68: fan shroud, 70: belt-type continuously variable transmission chamber, 71: partitioning wall, 72: seal member, 73: rubber member, 74a: steel plate, 74b: pressing ring, 75: V-belt, 76: drive pulley, 77: fixed side half pulley, 78: movable side half pulley, 79: boss, 80: cam plate, 81: dry weight roller, 86: driven pulley, 87: fixed side half pulley, 88: movable side half pulley, 89: inner sleeve, 90: outer sleeve, 91: centrifugal clutch, 92: reduction gear input shaft, 93: intermediate shaft, 94: output shaft, 95: drum brake, 96: drum brake shaft, 97: drum brake arm, 100: drive helical gear, 101: return spring, 102: sliding shaft, 103: driven helical gear, 104: rachet wheel, 105: friction spring, 110: starter motor, 111: magnet, 112: coil, 113: pinion, 115: jumping gear mechanism. 116: input gear, 117: jumping gear, 118: cooling fan, 130: circular opening, 131: base plate, 132: cylindrical rib, 133: outer peripheral wall, 134: seal ring, 135: bolt, 137: pulser, 138: reluctor, 140: oil pump, 141: driven gear, 142: pump shaft, 143: drive gear, 147: oil filter WE CLAIM: 1. An oil pump apparatus of an internal combustion engine of a type including an oil pump (140) in a crank case opposite to a belt-type continuously variable (70) transmission, characterized in that said crank case has, at a portion where side portions of said oil pump and its neighborhood are positioned, an opening (130) having an area being as small as not to permit penetration of a crank shaft (40) therethrough; and said opening is covered with a base plate of said oil pump so as to house said oil pump (140) in said crank case. 1. An oil pump apparatus of an internal combustion engine as claimed in claim 1, wherein said apparatus having a pulser (137) for detecting an action of a reluctor (138) provided on an outer rotor of an AC generator (60) provided at an end portion of said crank shaft, is projectingly provided on said base plate (131). 2. An oil pump apparatus of an internal combustion engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

2995-del-1996-abstract.pdf

2995-del-1996-claims.pdf

2995-del-1996-correspondence-others.pdf

2995-del-1996-correspondence-po.pdf

2995-del-1996-descraption (complete).pdf

2995-del-1996-drawings.pdf

2995-del-1996-form-1.pdf

2995-del-1996-form-13.pdf

2995-del-1996-form-19.pdf

2995-del-1996-form-2.pdf

2995-del-1996-form-3.pdf

2995-del-1996-form-4.pdf

2995-del-1996-form-6.pdf

2995-del-1996-gpa.pdf

2995-del-1996-petition-137.pdf

2995-del-1996-petition-138.pdf

abstract.jpg