Title of Invention

BALANCER FOR VEHICULAR ENGINE

Abstract

A balancer for a vehicular engine in which a starting clutch (85) allowing transmission of a rotational power of a crank shaft (36) to a drive wheel (WR) is contained in a crank case (33), wherein said starting clutch (85) includes a disk-like clutch plate (86) which is unmovable in the direction along its axial line parallel to that of said crank shaft (36) and which is rotatable around said axial line in synchronization with rotation of said crank shaft (36), a friction plate (87) opposed to said clutch plate (86), a lamp plate (88) which is disposed between said clutch plate (86) and said friction plate (87) and which is capable of pressing said friction plate (87) in the direction of friction-engaging said friction plate (87) with said clutch plate (86) in accordance with an increase in rotational speed of said clutch plate (86), and a clutch outer (89) which is formed into a bowl shape covering said lamp plate (88) and which is meshed with said friction plate (87); and characterized in that a balance weight (103) for adjusting an unbalance amount of said crank shaft (36) is provided on a portion, covered with said clutch outer (89), of said lamp plate (88).

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] PROVISIONAL/COMPLETE SPECIFICATION [See Section 10] "BALANCER FOR VEHICULAR ENGINE" HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, having a place of business at 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan GRANTED 6-6-2005 The following specification particularly describes the nature of the invention and the manner in which it is to be performed :- ORIGINAL 260/MUMNP/2000 [Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improved balancer for adjusting an unbalance amount of a crank shaft, which balancer is provided for a vehicular engine in which a starting clutch allowing transmission of a rotational power of the crank shaft is contained in a crank case. [Prior Art] A balancer for a vehicular engine has been known, for example, from Japanese Utility Model No. Hei 2-40343. [Problem to be Solved by the Invention] The above balancer is configured such that a balance weight rotated around its axial line parallel to that of a crank shaft in synchronization with rotation of the crank shaft is contained in a special small room provided in a crank case separately from a crank chamber for containing the crank shaft in order to avoid the stirring resistance and deterioration of oil accumulated in the crank case caused by stirring of oil by means of the balance weight. Accordingly, there arises a problem that the inner structure of the crank case is complicated and the size of the crank case is enlarged. In view of the foregoing, the present invention has been made, and an object of the present invention is to provide a balancer for a vehicular engine, characterized in that a balance weight is disposed in a crank case in such a manner as to make the stirring resistance of oil as small as possible and make the deterioration of oil as small as possible and also to avoid formation of a special room for the balance weight in the crank case. [Means for Solving the Problem] To achieve the above object, according to the present invention, there is provided a balancer for a vehicular engine in which a starting clutch allowing transmission of a rotational power of a crank shaft to a drive wheel is contained in a crank case, characterized in that the starting clutch includes a disk-like clutch plate which is unmovable in the direction along its axial line parallel to that of the crank shaft and which is rotatable around the axial line in synchronization with rotation of the crank shaft, a friction plate opposed to the clutch plate, a lamp plate which is disposed between the clutch plate and the friction plate and which is capable of pressing the friction plate in the direction of friction-engaging the friction plate with the clutch plate in accordance with an increase in rotational speed of the clutch plate, and a clutch outer which is formed into a bowl shape covering the lamp plate and which is meshed with the friction plate; and a balance weight for adjusting an unbalance amount of the crank shaft is provided on a portion, covered with the clutch outer, of the lamp plate. With this configuration, since the balance weight is provided on the lamp plate which is substantially entirely covered with the clutch plate, friction plate, and clutch outer, the amount of part of oil accumulated in the crank case flowing into and out of the starting clutch becomes very small and thereby the stirring of oil by the balance weight is made as small as possible. As a result, it is possible to dispose the balance weight in the crank case in such a manner as to make the stirring The subject invention relates to a balancer for a vehicular engine in which a starting clutch allowing transmission of a rotational power of a crank shaft to a drive wheel (WR) is contained in a crank case, wherein 3. said starting clutch includes a disk-like clutch plate which is unmovable in the direction along its axial line parallel to that of said crank shaft and which is rotatable around said axial line in synchronization with rotation of said crank shaft, a friction plate opposed to said clutch plate, a lamp plate which is disposed between said clutch plate and said friction plate and which is capable of pressing said friction plate in the direction of friction-engaging said friction plate with said clutch plate in accordance with an increase in rotational speed of said clutch plate, and a clutch outer which is formed into a bowl shape covering said lamp plate and which is meshed with said friction plate; and characterized in that a balance weight for adjusting an unbalance amount of said crank shaft is provided on a portion, covered with said clutch outer, of said lamp plate . resistance and deterioration of oil as small as possible and also to avoid formation of a special room for the balance weight in the crank case, and hence to eliminate the inconvenience that the inner s£ructure of the crank case is complicated and the size of the crank case is enlarged by disposing the balance weight in the crank case. [Mode for Carrying Out the Invention] Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. [Brief Description of the ACCOMPANYING Drawings] [Fig. 1] A side view of a bicycle with an auxiliary engine. [Fig. 2] A vertical sectional view of the engine, which is equivalent to a sectional view taken on line 2-2 of Fig. 3. [Fig. 3] A sectional view taken on line 3-3 of Fig. 2. [Fig. 4] A sectional view taken on line 4-4 of Fig. 2. [Fig. 5] An enlarged sectional view of a starting clutch. [Fig. 6] A front view, seen along line 6-6 of Fig. 5, showing a lamp plate. Figs. 1 to 6 show one embodiment of the present invention, wherein Fig. 1 is a side view of a bicycle with an auxiliary engine; Fig. 2 is a vertical sectional view of the engine, which is equivalent to a sectional view taken on line 2-2 of Fig. 3; Fig. 3 is a sectional view taken on line 3-3 of Fig. 2; Fig. 4 is a sectional view taken on line 4-4 of Fig. 2; Fig. 5 is an enlarged sectional view of a starting clutch; and Fig. 6 is a front view of a lamp plate seen in the direction shown by line 6-6 of Fig. 5. Referring first to Fig. 1, a body frame 10 of a bicycle (as one example of a small-sized vehicle) with an auxiliary engine includes a head pipe 11 at the front end of the body frame 10; a down frame 12 extending rearward from the head pipe 11; and a seat post 13 provided in parallel to the head pipe 11, the seat post 13 extending upward from the top of the rear end portion of the down frame 12. The head pipe 11, down frame 12, and seat post 13 are integrally formed from an aluminum alloy or the like by casting. The down frame 12 is formed into an approximately U-shape opened downward. A front fork 14 is steerably supported by the head pipe 11. A front wheel Wp is rotatably supported by the branched lower ends of the front fork 14, and a steering handlebar 15 is provided at the upper end of the front fork 14. A pair of right and left rear fork portions 16 extend rearward from the rear end of the down frame 12. A rear wheel WH as a drive wheel is rotatably supported between the rear ends of the rear fork portions 16. A pair of right and left stays 17 are provided between the rear ends of the rear fork portions 16 and an intermediate portion of the seat post 13 in the vertical direction. The seat post 13 is formed into a cylindrical shape. A supporting pipe 18 is inserted from above in the seat post 13 and is fixed thereto. Before the supporting pipe 18 is fixed to the seat post 13, the vertical position of the supporting pipe 18 inserted in the seat post 13 is adjustable. A driver's saddle 20 is mounted on the upper end of the supporting pipe 18. [0012] A fuel tank 21 is contained in a front half of the down frame 12. A cap 22 provided at the upper end of the fuel tank 21 projects upward from the down frame 12. A pedal shaft 23 is rotatably supported by a rear portion of the down frame 12. Two pedals 24 to be depressed by the driver sitting on the saddle 20 are fixed at both ends of the pedal shaft 23 in such a manner as to be disposed on both sides of the down frame 12. A drive sprocket 25 is disposed on the right side of the down frame 12 (as seen along the running direction of the bicycle with an auxiliary engine) in such a manner as to be coaxial with the pedal shaft 23. An endless chain 27 is wound between a driven sprocket 26 provided coaxially with the rear wheel WR and the drive sprocket 25. An engine 28, which generates a power for assisting a depressed force of the pedals 24 depressed by the driver is mounted on a lower portion of the down frame 12 of the body frame 10. In addition, part of a crank case 33 is configured by part of the down frame 12. Referring particularly to Figs. 2 to 4, a cylinder block 30 of the engine 28 is substantially horizontally disposed in such a manner that the axial line of a cylinder bore 31 of the cylinder block 30 is directed along the longitudinal direction of the bicycle. A cylinder head 32 disposed in front of the cylinder block 30 and the crank case 33 disposed behind the cylinder block 30 are connected to the cylinder block 30. A piston 34 is slidably fitted in the cylinder bore 31 formed in the cylinder block 30. A crank shaft 36 having the axial line extending along the width direction of the bicycle is connected to the piston 34 via a connecting rod 35. The crank case 33, in which the crank shaft 36 is contained, is composed of a lower case 37 connected to the cylinder block 30, and an upper case 38 formed by the rear portion of the down frame 12. The upper case 38 formed by the rear portion of the down frame 12, which is not directly connected to the cylinder block 30, is connected to the lower case 37. A parting plane 39 between the lower case 37 and the upper case 3 8 is set to be in parallel to the axial line of the cylinder bore 31 and the axial line of the crank shaft 36. The crank shaft 36 is contained in the lower case 37 of the crank case 33 which is composed of the lower and upper cases 37 and 38. Two portions, positioned on both sides of a crank pin 36a, of the crank shaft 3 6 are rotatably supported on the lower case 37 side. To be more specific, the crank shaft 36 integrally includes the crank pin 36a to which a connecting rod 35 is connected, crank webs 36b and 36c located on both sides of the crank pin 36a, and crank journals 36d and 36e projecting outwardly from the crank webs 36b and 36c, respectively, and the crank journals 36d and 36e are rotatably supported by holders 40 and 41 fixed in the lower case 37 via ball bearings 42 and 43, respectively. The holders 40 and 41 are held between the cylinder block 3Q and the lower case 37. The cylinder head 32, cylinder block 30, holders 40 and 41, and lower case 37 are co-fastened by means of four stud bolts 44 arranged around the cylinder bore 31 and screwed in the lower case 37 and nuts 45 screwed with the stud bolts 44. To be more specific, the stud bolts 44 with their one-ends planted in the lower case 37 by screwing are inserted in the holders 40 and 41, cylinder block 30 and cylinder head 32, and the nuts 45 are screwed with the other ends, projecting from the cylinder head 32, of the stud bolts 44. The cylinder head 32 is also fastened to the cylinder block 30 by means of one or a plurality of bolts 46 located apart from the arrangement positions of the nuts 45 screwed with the stud bolts 44. A generator 48 is disposed outside one of the holders 40 and 41, which is located on the left side with respect to the bicycle's posture directed forward in the longitudinal direction of the bicycle, that is, outside the left holder 40. A rotor 49 of the generator 48 is fixed to one end, projecting from the holder 40, of the crank shaft 36. A stator 50 of the generator 48 is fixed to a supporting cylinder 40a which integrally projects from the holder 40 in such a manner as to coaxially surround the one end of the crank shaft 36. A combustion chamber 54 facing to part of the top of the piston 34 is formed between the cylinder block 30 and the cylinder head 32 in such a manner as to direct forward in the longitudinal direction of the bicycle with its center offset rightward from the axial line of the cylinder bore 32. An ignition plug 57 with its inner end facing to the combustion chamber 54 is mounted in the cylinder head 32. An intake port 55 communicated to the combustion chamber 54 is provided in an upper portion of the cylinder block 30, and an exhaust port 56 communicated to the combustion chamber 54 is provided in a lower portion of the cylinder block 30. An intake valve 58 for permitting/forbidding the communication between the intake port 55 and the combustion chamber 54, and an exhaust valve 59 for permitting/forbidding the communication between the exhaust port 56 and the combustion chamber 54 are located over the cylinder bore 31 provided in the cylinder block 30. Both the valves 58 and 59 are supported by the cylinder block 30 in such a manner as to be openable/closable in the direction parallel to the axial direction of the cylinder bore 31, and are biased in the valve closing direction by springs. The intake valve 58 and the exhaust valve 59 are opened/closed by a valve system 60. The valve system 60 includes a timing drive gear 61 fixed to the crank shaft 36; a timing driven gear 63 rotatably supported by a supporting shaft 62 fixed to the cylinder block 3 0 and meshed with the timing drive gear 61; a cam 64 integrally formed on the timing driven gear 63; an intake side rocker arm 65 supported by the cylinder block 30 in such a manner as to be rocked along with the action of the cam 64 and linked with the intake valve 58; and an exhaust side rocker arm 66 supported by the cylinder block 30 in such a manner as to be rocked along with the action of the cam 64 and linked with the exhaust valve 59. The timing drive gear 61 is provided the other end, of the crank shaft 36, positioned outside the holder 41 located on the right side with respect to the bicycle's posture directed forward in the longitudinal direction of the bicycle. The timing drive gear 61 reduces the rotational power of the crank shaft 36 to half, and transmits the rotational power thus reduced to the timing driven gear 63 and the cam 64. In other words, the cam 64 is rotated at a rotational speed which is one half the rotational speed of the crank shaft 36. The downstream end of an intake pipe 72 communicated to the intake port 55 is connected to an upper portion of the cylinder block 30, and the upstream end of the intake pipe 72 is connected to the downstream end of a carburetor 73. The carburetor 73, positioned behind the fuel tank 21, is disposed such that part thereof is contained in the down frame 12 of the body frame 10. The upstream end of the exhaust pipe 74 communicated to the exhaust port 56 is connected to a lower portion of the cylinder block 30. The exhaust pipe 74 extends rearward while passing under the engine 28, and is connected to an exhaust muffler 75 (see Fig. 1) disposed between the engine 28 and the rear wheel WR. Referring again to Fig. 2, both ends of a main shaft 94 having an axial line parallel to that of the crank shaft 36 are rotatably supported by the lower case 37 of the crank case 33. One end of the pedal shaft 23 having an axial line parallel to that of the main shaft 94 is rotatably supported, via a ball bearing 95, by a left side wall (as seen along the running direction of the bicycle) of the upper case 38 of the crank case 33. The outer end of a rotating cylinder shaft 96, which coaxially surrounds the other end side of the pedal shaft 23, is rotatably supported, via a ball bearing 97, by a right side wall (as seen along the running direction of the bicycle) of the upper case 38. The inner end of the rotating cylinder shaft 96 is relatively rotatably supported by the pedal shaft 23. A roller bearing 98 is interposed between the outer end of the rotating cylinder shaft 96 and the pedal shaft 23. That is to say, the pedal shaft 23 and the rotating cylinder shaft 96, which are coaxial with each other, are relatively rotatably supported by the upper case 38 of the crank case 33. The drive sprocket 25 is fixed to the outer end of the rotating cylinder shaft 96. A primary drive gear 99 is fixed to the one crank web 36c of the pair of the crank webs 36b and 36c of the crank shaft 36. A primary driven gear 100 meshed with the primary drive gear 99 is relatively rotatably supported by the main shaft 94. Referring particularly to Fig. 5, a starting clutch 85 is mounted to the main shaft 94. The starting clutch 85 includes a disk-like clutch plate 86, a friction plate 87, a lamp plate 88, and a clutch outer 89. The clutch plate 86 is unmovable in the direction along the axial direction of the main shaft 94 having the axial line parallel to that of the crank shaft 36 and is rotatable around the axial line of the main shaft 94. The friction plate 87 is disposed opposite to the clutch plate 86. The lamp plate 88 is disposed with the friction plate 87 put between the clutch plate 86 and the same and is used for pressing the friction plate 87 in the direction of friction-engaging the friction plate 87 with the clutch plate 86. The clutch outer 89 is formed in a bowl shape covering the lamp plate 88 and is meshed with the friction plate 87. A cylindrical boss 90 is spline-connected to the main shaft 94 at a specific axial position, and the primary driven gear 100 is relatively rotatably supported by the boss 90. The inner periphery of the clutch plate 86 is spline-connected to the outer periphery of the boss 90. The primary driven gear 100 is connected to the clutch plate 86 via a damper 101. The lamp plate 88 is spline-connected to the boss 90 in such a manner as to be relatively movable in the axial direction. A spring 91, which generates a spring force acting to extend a gap between the clutch plate 86 and the lamp plate 88, is provided between the clutch plate 86 and the lamp plate 88. Referring particularly to Fig. 6, a surface portion, opposed to the clutch plate 86, of the lamp plate 88 has grooves 102 for containing weight rollers 92 allowed to be rolled in the radial direction of the main shaft 94. A back plate 93 being in contact with the weight rollers 92 on the side opposed to the lamp plate 88 is mounted to the boss 90. The outer end side of each of the containing grooves 102 in the radial direction of the main shaft 94 has a tilt surface 102a tilted such that a point in closer proximity to the outer end of the tilt surface 102a is nearer to the back plate 93. The clutch outer 89 is formed in a bowl shape covering the lamp plate 88, weight rollers 92 and back plate 93, and is relatively rotatably supported by the main shaft 94. The outer periphery of the friction plate 87 is meshed with the opening end of the clutch outer 89, and an output gear 104 is fixed to the clutch outer 89. The operation of the starting clutch 85 will be described below. The clutch plate 86 is driven by the crank shaft 3 6 via the primary drive gear 99, primary driven gear 100, and damper 101. When the rotational speed of the clutch plate 86 exceeds a specific value, the weight rollers 92 ascend the tilt surfaces 102a by the centrifugal forces applied thereto, and thereby the lamp plate 88 presses the friction plate 87 in the direction of friction-engaging the friction plate 87 with the clutch plate 86. As a result, the clutch plate 86 is connected to the clutch outer 89 via the friction plate 87, so that the rotational power of the crank shaft 36 in the direction of forward movement is transmitted to the output gear 104. A balance weight 103 for adjusting the unbalance amount of the crank shaft 36 is integrally provided on a portion covered with the clutch outer 89 of the lamp plate 88 of the starting clutch 86, for example, provided on an approximately semi-periphery of the lamp plate 88. The output gear 104 of the starting clutch 85 is connected to the rotating cylinder shaft 96 via a first planetary gear type speed reducer 105. A carrier 106 of the first planetary gear type speed reducer 105 is mounted to the rotating cylinder shaft 96 in such a manner as to be forbidden in its rotation relative to the rotating cylinder shaft 96. A sun gear 107 is meshed with the output gear 104. A ring gear 108 is engaged with the main shaft 94 in such a manner as to be forbidden in its rotation around the axial line of the rotating cylinder shaft 96. A second planetary gear type speed reducer 111 is mounted to the pedal shaft 23 in such a manner as to be opposed to the first planetary type speed reducer 105 with a gap put therebetween. A carrier 112 of the second planetary gear type speed reducer 111 is engaged with the upper case 38 in such a manner as to be forbidden in its rotation around the axial line of the pedal shaft 23. A ring gear 113 is supported by the pedal shaft 23 in such a manner as to be rotatable around the axial line of the pedal shaft 23, and a sun gear 114 is supported by the ring gear 113 in such a manner as to be rotatable around the axial line of the ring gear 113. A shifter 115 coaxial with the pedal shaft 23 is mounted, via a helical gear, on the pedal shaft 23 at a position between the first and second planetary gear type speed reducers 105 and 111. A spring 116, which is forbidden in its rotation around the axial line of the pedal shaft 23 by engagement with the upper case 38, is friction-engaged with the outer periphery of the shifter 115. When the pedal shaft 23 is rotated in the direction of forward movement of the bicycle, the shifter 115 being in the state in which the rotation thereof is forbidden by the friction engagement with the spring 116 is moved onto the first planetary gear type speed reducer 105 side. Meanwhile, when the pedal shaft 23 is rotated in the direction of backward movement of the bicycle, the shifter 115 being in the state in which the rotation thereof is forbidden by the friction engagement with the spring 116 is moved onto the second planetary gear type speed reducer 111 side. The shifter 115 can be ratchet-engaged with the carrier 106 of the first planetary gear type speed reducer 105. With this ratchet-engagement, the power transmission from the shifter 115 to the carrier 106 is permitted but the power transmission from the carrier 106 to the shifter 115 is forbidden. Further, the shifter 115 can be ratchet-engaged with the ring gear 113 of the second planetary gear type speed reducer 111. With this ratchet-engagement, the power transmission from the shifter 115 to the ring gear 113 is permitted but the power transmission from the ring gear 113 to the shifter 115 is forbidden. Accordingly, when the pedal shaft 23 is rotated in the direction of forward movement of the bicycle by depressing the pedals 24, the shifter 115 is moved until it is ratchet-engaged with the carrier 106 of the first planetary gear type speed reducer 105. In such a state, by applying a rotational power over the rotational resistance applied to the shifter 115 by friction engagement with the spring 116 to the pedal shaft 23, the rotational power can be transmitted from the pedal shaft 23 to the rotating cylinder shaft 96 via the shifter 115 and carrier 106. On the other hand, a helical gear 117 meshed with the outer periphery of the sun gear 114 of the second planetary gear type speed reducer 111 is rotatably supported by the main shaft 94, and a spring 118 forbidden in its rotation around the axial line of the main shaft 94 by engagement with the lower case 37 is friction-engaged with the helical gear 117. A rotating member 119 opposed to the helical gear 117 with a gap put therebetween is mounted on the main shaft 94 in such a manner as to be forbidden in its rotation relative to the main shaft 94. When the pedal shaft 23 is rotated in the direction of backward movement of the bicycle by depressing the pedals 24, the shifter 115 is moved until it is ratchet-engaged with the ring gear 113 of the second planetary gear type speed reducer 111. In such a state, by applying a rotational power over the rotational resistance applied to the shifter 115 by friction engagement with the spring 116 to the pedal shaft 23, the rotational power is transmitted from the pedal shaft 23 to the helical gear 117 via the shifter 115 and the second planetary gear type speed reducer 111. As a result, the helical gear 117 being in the state in which the rotation thereof is forbidden by friction engagement with the spring 118 is moved to the rotating member 119 side. Further, the helical gear 117 can be ratchet-engaged with the rotating member 119. With this ratchet-engagement, the power transmission from the helical gear 117 to the member 119 is permitted but the power transmission from the rotating member 119 to the helical gear 117 is forbidden. Accordingly, by rotating the pedal shaft 23 in the direction of backward movement of the bicycle to move the helical gear 117 until the helical gear 117 is ratchet-engaged with the rotating member 119, and applying a rotational power over the rotational resistance applied to the helical gear 117 by friction engagement with the spring 118 to the pedal shaft 23, the rotational power can be transmitted from the pedal shaft 23 to the main shaft 94 via the shifter 115, second planetary gear type speed reducer 111, helical gear 117, and rotating member 119. Further, the rotational power of the main shaft 94 is transmitted to the crank shaft 36 via the clutch plate 86 of the starting clutch 85, damper 101, primary driven gear 100, and primary drive gear 99, with a result that the engine 28 is started. In this way, in accordance with the rotation of the pedal shaft 23 in the direction of forward movement or backward movement of the bicycle, the shifter 115 is selectively connected to the first planetary gear type speed reducer 105 for transmitting the rotational power of the pedal shaft 23 in the direction of forward movement to the rotating cylinder shaft 96 or connected to the second planetary gear type speed reducer 111 for transmitting the rotational power of the pedal shaft 23 in the direction of backward movement to the helical gear 117, and the power having been transmitted from the second planetary gear type speed reducer 111 to the helical gear 117 is further transmitted to the main shaft 94. Accordingly, it is possible to facilitate the start¬up of the engine 28 by rotation of the pedal shaft 23 in the direction of backward movement, with a simple structure without use of a complicated one-way clutch. Referring again Figs. 2 and 3, the lower end opening, connected to the down frame 12, of the seat post 13 is blocked with a breather cap 77 having a breather pipe 76. The breather cap 77 is held between the upper case 38 and a pressing plate 78 fastened to the upper case 38. A labyrinth 79 with one end communicated to the crank case 3 3 and the other end communicated to the breather pipe 76 is formed between the breather cap 77 and the pressing plate 78. A breather gas generated in the crank case 33 flows into the breather pipe 76, and during a period of time in which the breather gas passes through the labyrinth 79, an oil component is separated from the breather gas. The breather pipe 76 is connected to an air cleaner (not shown) disposed in the down frame 12, so that the breather gas is mixed in an intake air sucked from the air cleaner into the engine 28 via the carburetor 73. The function of this embodiment will be described below. The crank case 33 of the engine 28 is formed by connecting the lower and upper cases 37 and 38 dividable along the parting plane 39 extending in parallel to the axial line of the crank shaft 36, and only the lower case 38 is connected to the cylinder block 30. Accordingly, it is possible to simplify the seal structure of the connection plane between the cylinder block 30 and the crank case 33 and hence to improve the sealing performance. Since the two portions, on both sides of the crank pin 36a, of the crank shaft 36 are rotatably supported by the lower case 37, it is possible to enhance the supporting rigidity of the crank shaft 36 and hence to improve the durability of the crank shaft 36. Since the parting plane 39 is in parallel to the axial line of the cylinder bore 31 of the cylinder block 30, the lower case 37 can be formed into a bowl-like shape with its upper side opened. This makes it possible to simplify the shape of the lower case 37. Since the crank shaft 36 is supported by the holders 40 and 41 fixed to the lower case 37 via the ball bearings 42 and 43 respectively, it is possible to accurately support the crank shaft 36 while avoiding the increase number of steps. To be more specific, in the case of adopting a structure in which the crank shaft 36 is supported by bearings mounted in supporting holes formed in a pair of members arranged on both end sides of the crank shaft 36, the supporting accuracy of the crank shaft 36 must be ensured by simultaneously machining the supporting holes of both the members in a state in which the members are assembled. According to the present invention, however, since the ball bearings 42 and 43 are mounted in the holders 40 and 41, it is possible to eliminate the above-described simultaneous machining and hence to accurately support the crank shaft 36 by the holders 40 and 41. The balance weight 103 for adjusting an unbalance amount of the crank shaft 36 is provided on a portion, covered with the clutch outer 89, of the lamp plate 88 of the starting clutch 85. Accordingly, the amount of part of oil accumulated in the crank case 33 flowing into and out of the starting clutch 85 becomes very small, and thereby the stirring resistance of oil by the balance weight 103 is made as small as possible. As a result, it is possible to dispose the balance weight 103 in the crank case 33 in such a manner as to make the stirring resistance and deterioration of oil as small as possible and also to avoid formation of a special room for the balance weight 103 in the crank case 33, and hence to eliminate the inconvenience that the inner structure of the crank case 33 is complicated and the size of the crank case 3 3 is enlarged by disposing the balance weight 103 in the crank case 33. While the embodiment of the present invention has been described in detail, the present invention is not limited thereto, and it is to be understood that various changes in design may be made without departing from the scope of the claim. [Effect of the Invention] As described above, according to the present invention, it is possible to dispose a balance weight in a crank case in such a manner as to make the stirring resistance and deterioration of oil as small as possible and also to avoid formation of a special room for the balance weight in the crank case, and hence to eliminate the inconvenience that the inner structure of the crank case is complicated and the size of the crank case is enlarged by disposing the balance weight in the crank case. [Explanation of Characters] 28: engine, 33: crank case, 36: crank shaft, 85: starting clutch, 86: clutch plate, 87: friction plate, 88: lamp plate, 89: clutch outer, 103: balance weight, WR: rear wheel (drive wheel) We claim: 1. A balancer for a vehicular engine in which a starting clutch (85) allowing transmission of a rotational power of a crank shaft (36) to a drive wheel (WR) is contained in a crank case (33), wherein said starting clutch (85) includes a disk-like clutch plate (86) which is unmovable in the direction along its axial line parallel to that of said crank shaft (36) and which is rotatable around said axial line in synchronization with rotation of said crank shaft (36), a friction plate (87) opposed to said clutch plate (86), a lamp plate (88) which is disposed between said clutch plate (86) and said friction plate (87) and which is capable of pressing said friction plate (87) in the direction of friction-engaging said friction plate (87) with said clutch plate (86) in accordance with an increase in rotational speed of said clutch plate (86), and a clutch outer (89) which is formed into a bowl shape covering said lamp plate (88) and which is meshed with said friction plate (87); and characterized in that a balance weight (103) for adjusting an unbalance amount of said crank shaft (36) is provided on a portion, covered with said clutch outer (89), of said lamp plate (88). 2. A balancer for a vehicular engine substantially as hereinbefore described with reference to the accompanying drawings. Dated this 23rd day of March, 2000. [RANJNA MEHTA DUTT] OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Documents:

260-mum-2000-cancelled pages(6-6-2005).pdf

260-mum-2000-claims(granted)-(6-6-2005).doc

260-mum-2000-claims(granted)-(6-6-2005).pdf

260-mum-2000-correspondence(22-3-2006).pdf

260-mum-2000-correspondence(ipo)-(6-6-2007).pdf

260-mum-2000-drawing(16-3-2001).pdf

260-mum-2000-form 1(23-3-2000).pdf

260-mum-2000-form 19(15-4-2004).pdf

260-mum-2000-form 2(granted)-(6-6-2005).doc

260-mum-2000-form 2(granted)-(6-6-2005).pdf

260-mum-2000-form 3(23-3-2000).pdf

260-mum-2000-form 3(23-3-2001).pdf

260-mum-2000-form 3(6-6-2005).pdf

260-mum-2000-form 5(23-3-2000).pdf

260-mum-2000-petition under rule 138(9-6-2005).pdf

260-mum-2000-power of authority(10-8-2000).pdf

260-mum-2000-power of authority(6-6-2005).pdf

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