Title of Invention

CAM CHAIN TENSIONER FOR VEHICLE ENGINE.

Abstract

To maintain reliable operation of a push rod in such a manner as to reliably replenish an oil sump with oil during engine operation and reduce friction loss of a rotating member in a cam tensioner for a vehicle engine where a rotary member is at least partly immersed in oil housed in an operating chamber defined between a crankcase and a crankcase cover and is fixedly coupled to a crankshaft; an oil sump opens on a bottom of a cam chain chamber which houses a cam chain for transmitting power to a cam shaft from the crankshaft, and is formed in an engine body in order to feed oil to an oil chambwer and maintain a push rod at a predetermined position, with the cam chain being movable in the cam chain chamber. [Resolving Means] An oil sump 137 is capable of collecting oil scattered in accompaniment with the rotation of a rotating member 121 and an engine body is formed so as to be open an the end on the side of an operating chamber 106 at the bottom 124 a of a cam chain chamber 124, with the oil sump 137 communicating via a throttle hole 149 within the operating chamber 106.

Full Text

[Detailed Description ot the invention] (Field of the Invention] This invention relates to a cam tensioner for a vehicle engine where a rotary member is at least partly immersed in oil housed in an operating chamber defined between a crankcase and a crankcase cover and is fixedly coupled to a crankshaft; an oil sump opens on a bottom of a cam chain chamber which houses a cam chain for transmitting power to a cam shaft from the crankshaft, and is formed in an engine body in order to feed oil to an oil chamber and maintain a push rod at a predetermined position, with the cam chain being movable in the cam chain chamber. [Related Art] The foregoing cam chain tensioner for a vehicle is disclosed, for example, in Japanese Patent Laid-open No. Hei 9-49433. [Problems to be Solved by the Invention] In the related art, oil supplied to a cylinder head and its peripheral area is collected and returned to an oil sump. Therefore, the amount of oil returned to the oil sump varies immediately after an engine is started or when an engine body swings, so that the operation of a push rod tends to become unstable due to not enough oil being stored in the oil sump. [0004] This invention has been contemplated in order to overcome the foregoing problems of the related art, and is intended to provide a cam chain tensioner for a vehicle, in which during the operation of an engine, a predetermined amount of oil is supplied to an oil sump in order to guarantee the reliable operation of a push rod. Further, it is possible to reduce friction loss of a rotating member which scatters oil in an operating chamber. [Means to Solve the Problems] In order to achieve the above object, the present invention is characterized by a cam chain tensioner for a vehicle engine, wherein: a crankcase cover is attached to a crankcase of an engine body and defines an operating chamber with the crankcase; a drive sprocket and a rotating member having at least a part thereof immersed in oil housed in the operating chamber for the purpose of scattering oil therein are fixedly attached to a crankshaft rotatably supported by the crankcase, in the operating chamber; a cam chain chamber houses an endless cam chain extending around a driven sprocket fixedly coupled to the drive sprocket and a cam shaft, the cam chain being movable in the cam chain chamber, and the cam chain chamber has a bottom thereof positioned above a bottom of the operating chamber, is formed in the engine body and extends substantially along the length of a vehicle; a push rod having one end thereof connected with a tension member in contact with the cam chain is urged by a spring to operate the tension member which tensions the cam chain; an oil sump capable of feeding oil to an oil chamber where the push rod has the other end thereof housed in order to maintain a position thereof against reactive force from the cam chain is provided in the engine body and opens on a bottom of the cam chain chamber on the side of the operating chamber, is capable of collecting oil scattered in response to the rotation of the rotating member, and communicates with the operating chamber via a throttle hole. According to the foregoing feature, oil scattered by the rotating, member that rotates in response to the rotation of the crankshaft can be collected in the oil sump. During the operation of the engine, a predetermined amount of oil can be reliably stored in the oil sump, thereby assuring reliable operation of the push rod. Since some of the oil is returned to the oil sump, a level of oil in the operating chamber is lowered, which is effective in reducing friction loss of the rotating member. According to the present invention, there is provided a cam chain tensioner for a vehicle engine in which a crankcase cover is attached to a crankcase of an engine body and defines an operating chamber with the crankcase; a drive sprocket and a rotating member having at least a part thereof immersed in oil housed in the operating chamber for the purpose of scattering oil therein are fixedly attached to a crankshaft rotatably supported by the crankcase, in the operating chamber; a cam chain chamber houses an endless cam chain extending around a driven sprocket fixedly coupled to the drive sprocket and a cam shaft, the cam chain being movable in the cam chain chamber, and the cam chain chamber has a bottom thereof positioned above a bottom of the operating chamber, is formed in the engine body and extends substantially along the length of a vehicle (V); a push rod having one end thereof connected with a tension member in contact with the cam chain is urged by a spring to operate the tension member which tensions the cam chain; an oil sump capable of feeding oil to an oil chamber where the push rod has the other end thereof housed in order to maintain a position thereof against reactive force from the cam chain is provided in the engine body and opens on the bottom of the cam chain chamber, characterized in that: said oil sump is capable of collecting oil scattered in response to the rotation of the rotating member and is provided in the engine body and opens on the bottom of the cam chain chamber) on the side of the operating chamber, and communicates with the operating chamber via a throttle hole. [Brief Description Of The Numerals] Fig. 1 is a side view of a motorcycle. Fig. 2 is an enlarged cross section of the motorcycle, taken along line 2-2 in Fig. 1. Fig. 3 is a cross section, taken along line 3-3 in Fig. 2. Fig. 4 is an enlarged cross section, taken along line 4-4 in Fig. 1 . Fig. 5 is a cross section, taken along line 5-5 in Fig. 2. Fig. 6 is an enlarged cross section, taken along line 6-6 in Fig. 5. Fig. 7 is an enlarged cross section of the main part shown in Fig. 5. Fig. 8 is a cross section, take along line 8-8 in Fig. 5. Fig. 9 is a cross section, taken along line 9-9 in Fig. 2. Fig. 10 shows a crankcase cover, observed from an inner side thereof. [Description of the Embodiment] The invention will be described with reference to one embodiment shown in the accompanying drawings. Fig. 1 to Fig. 10 show the embodiment of the invention. Fig. 1 is a side view of a motorcycle to which the invention is applied. Fig. 2 is an enlarged cross section of the motorcycle, taken along line 2-2 in Fig. 1 . Fig. 3 is a cross section, taken along line 3-3 in Fig. 2. Fig. 4 is an enlarged cross section, taken along line 4-4 in Fig. 1. Fig. 5 is a cross section, taken along line 5-5 in Fig. 2. Fig. 6 is an enlarged cross section, taken along line 6-6 in Fig. 5. Fig. 7 is an enlarged cross section of the main part shown in Fig. 5. Fig. 8 is a cross section, take along line 8-8 in Fig. 5. Fig. 9 is a cross section, taken along line 9-9 in Fig. 2. Fig. 10 shows a crankcase cover, observed from an inner side thereof. Referring to Fig. 1 first of all, a vehicle frame F of a motorcycle V taken as a small vehicle is constituted by bending one steel pipe, and comprises: a head tube 15 sloping forward and downward; a down tube 16 extending rearward and downward from a bottom of the head tube 15; a bottom tube 17 extending from the bottom of the down tube 16 substantially horizontally towards the rear; and a rear tube 18 extending upward and rearward from a rear end of the bottom tube 17. A front fork 19 supporting a front wheel WF and a steering bar handle 20 are steerably attached to the head tube 15. A front lamp 21 is attached to the steering bar handle 20. A footrest 22 is provided at the bottom of the down tube 16 and on the bottom tube 17. A support post 23a for a saddle 23 is fitted into an upper part of the rear tube 17, and is clamped by a clamp 24 so that the position of the saddle 23 is adjustable. A support bracket 25 is attached on the rear tube 17, and a rubber holder 26 is fixedly attached above the support bracket 25. A power unit P supporting a rear wheel WR is coupled to the support bracket 25 via a support shaft 27, so that the power unit P can move up and down. The power unit P is coupled to a rubber member 28 held by the rubber holder 26 in order to elastically regulate the upward and downward movement of the power unit P round the axis of the support shaft 27. A rear cover 30 integral with a rear fender 29 is positioned above the rear wheel WR, and is attached to the clamp 24 and the rubber holder 26. A lamp unit 31 including a tail lamp and turn signal lamps is attached at the rear end of the rear cover 30. The rear cover 30 houses a fuel tank 32 therein, and is structured so as to be partially opened at its upper part in order to supply oil to the fuel tank 32. Referring to Figs. 2 and 3, the power unit P is provided with an air-cooled single cylinder four cycle engine E and a transmission M, and is positioned at the left side of the motorcycle V in the moving direction thereof and beside the rear wheel WR. The engine body 34 of the engine E includes: right and left crankcases 36 and 35 for rotatably supporting a crankshaft 40; a cylinder head 38 having a cylinder 37 as an integral part and commonly coupled to the right and left crankcases 36 and 35; and a head cover 39 coupled to the cylinder head 38. A combustion chamber 43 is defined between the cylinder head 38 and a piston 42 slidably fitted in the cylinder 37. The piston 42 is coupled to the crankshaft 40 via a connecting rod 44 and a crank pin 45. Therefore, the engine E is positioned beside the rear wheel WR with the operating axis of the piston 42 inclined forward until it becomes substantially horizontal. A cam shaft 47 is rotatably supported by a cam holder 46 provided on the cylinder head 38, and includes, as integral parts, an intake cam 49 for opening and closing an intake valve 48 and an exhaust cam 51 for opening and closing an exhaust valve 50. With reference to both Figs. 4 and 5, the left crankcase 35 has an upward extending case part 35a as an integral part, while the right crankcase 36 has an upward extending case part 36a as an integral part. The right and left case parts 36a and 35a are coupled to constitute a transmission case 52. A swing arm 53 is provided on the case part 35a of the left crankcase 35, as an integral part, is positioned above the engine body E, and extends forward of the motorcycle V. The swing arm 53 is formed such that its vertical section orthogonal with the length direction of the motorcycle V is substantially in the shape of letter U whose open side faces opposite to the rear wheel WR. Further, the swing arm 53 includes a bulging portion 53a that extends along the front part of the rear wheel WR. A hanger 54 is positioned at the front end of the swing arm 53, as an integral part, and is supported, via rubber bushes 55, 55, by the support shaft 27 supported by the bracket 25 of the body frame F. iQ020] A pair of coupling brackets 56, 56 positioned above the hanger 54 are attached to the front part of the swing arm 53, as an integral part. An air cleaner cover 58 is attached to the swing arm 53 using a plurality of bolts 57••• at a position opposite to the rear wheel WR. A partition 59 that is positioned at the middle of the swing arm 53 extending along the length of the motorcycle V is brought into contact with a partition 60 that is provided in the air cleaner cover 58 in accordance with the partition 59, so that a front air cleaner chamber 61 and a rear carburetor housing chamber 62 are respectively formed between the swing arm 53 and the air cleaner cover 58. A support wall 63 is formed between the front end of the swing arm 53 extending along the length of the motorcycle V and the partition 59, and between upper and lower side walls of the swing arm 53. A continuous recess 64 is formed on the support wall 63 and on an end of the air cleaner cover 58 near the front side wall of the swing arm 53, and is shaped in accordance with the bulging part 53a of the swing arm 53. A peripheral edge of a cleaner element 65 is fitted in the recess 64. Further, the air cleaner cover 58 is provided with a projection 66 for sandwiching the cleaner element 65 together with the support wall 63 and bringing a tip of the cleaner element 65 into contact with the support wall 63. A screw 67 inserted through the invervening wall with a projection 66 from outside the air cleaner cover 58 is screwed into the support wall 63. The air cleaner chamber 61 is partitioned into a pre-purification chamber 6la within the bulging portion 53a and a purification chamber 6 la, with external air being introduced into the pre-purification chamber 6 la. In Fig. 6, an air inlet 68 communicating with the pre-purification chamber 6 la is provided at the bulging portion 53a of the swing arm 53 on the opposite side from the air cleaner cover 58, with a cover part 69 covering the air inlet from above being formed integrally with the bulging portion 53a. A plurality of mutually crossing ribs 70 ... are integrally provided at the inner surface of the swing arm 53 at the air cleaner chamber 61, with each of the ribs 70 ... within the pre-purification chamber 61a coming into contact with the cleaner element 65. As the pre-purification chamber 6la is not partitioned into a plurality of chambers by these ribs 70 ..., an approximately U-shaped notch 71 is provided at the end on the side of the cleaner element 65 for the ribs 70 ... within the pre-purification chamber 6 la. Air entering the pre-purification chamber 6la from the air inlet 68 then flows through so as to be scattered by substantially the whole surface of the cleaner element 65 and air purified by the cleaner element 65 then passes into the purification chamber 61 b. A carburetor 74 is housed within a carburetor housing chamber 62, i.e. the swing arm 53 is positioned up from the cylinder head 38 of the engine body 34 and the carburetor 74 is housed within the carburetor housing chamber 62 formed between the swing arm 53 and the air cleaner cover 58. The swing arm 53 is therefore positioned between the cylinder head 38 and the carburetor 74 and is coupled to the support bracket 25 of the vehicle frame F in such a manner as to be capable of rocking. A rubber inlet side connecting tube 75 fits into the inlet of the carburetor 74, with the inlet side connecting tube 75 being interposed between partitions 59 and 60 so as to communicate with the purification chamber 61b. One end of an outlet side connecting tube 76 that curves in an approximate L-shape is fastened to the outlet of the carburetor 74 and a flange 77 is provided at the other end of the outlet side connecting tube 76. A through hole 78 is provided at the swing arm 53 and attachment bearing surfaces 79 and 80 surrounding the through hole 78 are formed at the outer surface thereof within the swing arm 53. A thermal insulator 81 is interposed between the flange 77 of the outlet side connecting tube 76 and the attachment bearing surface 79. One end of an intake pipe 82 is inserted to the outlet side connecting tube 77 after passing through the through hole 78 and the thermal insulator 81 and the other end of the intake pipe 82 is connected to the cylinder head 38. A flange 83 coming into contact with the attachment bearing surface 80 is fixed to the enter of the intake pipe 82 and the flanges 77 and 82 interposed between the thermal insulator 81 and the swing arm 53 are fastened with a plurality of bolts such as a pair of bolts 84, 84, As a result, the carburetor 74 is fixed to the swing arm 53 and the intake pipe 82 fixed to the swing arm 53 so as to communicate with the cylinder head 38 passes through the swing arm 53 so as to be connected to the carburetor 74. A throttle wire 85 for driving a throttle valve (not shown) of the carburetor 74 passes through the upper part of the swing arm 53 and extends to the side of the steering handle 20. A fuel cock 87 attached at the carburetor 74 for changing over of supplying and interrupting of fuel from a fuel inlet pipe 86 connected to the fuel tank 32 (refer to Fig. 1) extends to the outer side of the air cleaner cover 58 in order to enable operation from the outer side of the air cleaner cover 58. A plurality of air ventilation holes 88 that cause air to flow between the inside and outside of the carburetor housing chamber 62 in order to prevent overheating of the carburetor housing chamber 62 are provided at the portion corresponding to the carburetor housing chamber 62 of the air cleaner cover 58. The exhaust pipe 89 through which exhaust gas from the cylinder head 38 flows is provided so as to extend through the lower and front side of the power unit P to the top of both of the case parts 35a and 36a and is connected to the silencer 90 supported at the upper part of the case parts 35a and 36a. An input gear 94 engaging with an output gear 93 fixed to one end of the crankshaft 40, a transmission M and a start clutch 95 lying between the input gear 94 and the transmission M are housed within the transmission case 52 comprised of the case parts 35a and 36a. The input gear 94 and the start clutch 95 have the same parallel axis as the crankshaft 40 and are attached to the main axis 96 supportedly fixed at both ends in the axial direction by the case parts 35a and 36a. The transmission M is provided with, for example, a four-stage gear train 98, 99, 100 and 101, selectively switched between a plurality of stages, provided between the main axis 96 and a final axis 97 having an axis parallel to the main axis 96 and being supported so as to be freely rotatable by the case parts 35a and 36a in such a manner that one end projects from the case part 36a. A wheel 103 comprising a tire 102 and a rear wheel WR is then attached to the end projecting from the transmission case 52 of the final axis 97. A crankcase cover 105 is connected to the left crankcase 35 including the case part 35a from the opposite side to that of the right crankcase 36 and a operating chamber 106 is formed between the left crankcase 35 and the crankcase cover 105. A generator 111 comprising a rotor 109 with a magnet 108 fixed to the inner surface of a bowl-shaped outer tube 107 fixed to the crankshaft 40 and a stator 110 fixed to the crankcase cover 105 is housed within the operating chamber 106. A kick spindle 112 having an axis parallel to the crankshaft 40 is supported so as to be freely rotatable at the crankcase cover 1 05 and a kick pedal is fixed to the end of the kick spindle 112 projecting to the outer side from the crankcase cover 105. A kick spindle gear 114 is fixed to the kick spindle 112 and a gear train 115 including this kick spindle gear 114 is coupled to the crankshaft 40 via a start clutch 116. A coiled spring 117 is provided between the crankcase cover 105 and the kick spindle gear 114. When the operation of stepping on the kick pedal 1 1 3 is complete, the coiled spring 117 urges the kick pedal 113, i.e. the kick spindle 112 to return to it' s original position. A starter motor 1 1 8 is housed and fixed within the case part 35a of the left crankcase 35. An output gear 119 provided at the output axis of this starter motor 1 1 8 can then be coupled to a ring gear 121 taken as a rotating member rotating integrally with the crankshaft 40 via an over-running clutch 120. The ring gear 121 is formed as a single body at the outer tube 107 of the rotor 1 09 of the generator 1 1 1 by carrying out a burring process and a filing process etc. to the open end of the bowl-shaped outer tube 107. By providing the ring gear 121 integrally with the outer tube 107 of the generator 1 1 1 , as well as the number of parts being reduced and the number of assembly processes being reduced, an increase in the strength of the outer tube 107 is also brought about. With the engine body 34, a cam chain chamber 124 extending in an approximately horizontal direction through the operating chamber 106 is formed at the cylinder head 38 and the head cover 39. An endless cam chain 127 wound onto a drive sprocket 125 fixed to the crankshaft 40 between the generator 111 within the operating chamber 106 and the left crankcase 35 and a driven sprocket 126 fixed to the cam shaft 47 within the cam chain chamber 124 is housed so as to be capable of being transported at the operating chamber 106 and the cam chain chamber 124. A cylindrical boss 128 is provided at the left crankcase 35 in the vicinity of the connector for the operating chamber 106 and the cam chain chamber 124 in such a manner as to have an axis parallel with the crankshaft 40 and a tension arm 130 is supported at the boss 128 by a screw-in support shaft 129 so as to be capable of rocking. A tension sprocket 131 taken as a tension member is axially supported at one end of this tension arm 130 and engages with the cam chain 127. The upper end of a push rod 132 is connected to the other end of the tension arm 130. •[0040] The cam chain chamber 124 is formed at the engine body 34 so that the bottom 1 24a thereof is arranged above the bottom of the operating chamber 106 and an oil separator 133 arranged at the end on the side of the operating chamber 106 of the bottom 124a of the cam chain chamber 124 is fastened to the left crankcase 35. Referring to Fig. 7 and Fig. 8, a concave part 134 open to the side of the crankcase cover 105 is present at the end of the side of the operating chamber 106 of the bottom 124a and an arc-shaped wall 135 is provided so as to be interposed with the operating chamber in the vicinity of and facing the ring gear 121. An oil separator 133 is fastened using a bolt 136 to the left crankcase 35 so that the open side of the crankcase cover 105 of the concave part 134 is closed. An oil sump 137 open to the bottom 124a of the cam chain chamber 124 is formed from the concave part 134 and the oil separator 133. On the other hand, oil is gathered within the operating chamber 106 and oil scattered by the ring gear 121 rotating in the direction shown by the arrow 138 of Fig. 7 within the operating chamber 106 is received by the oil sump 137. At the oil separator 133, a bottom guide tube 139 is integrally provided with the upper end at a position below the bottom 124a of the cam chain chamber 124 extending vertically within the oil sump 137 with the upper end thereof open, the cylindrical push rod 132 fitting into the guide tube 139 so as to be slidable. An oil chamber 140 is formed between the lower end of the push rod 132 and the closed end of the guide tube 139, with the oil chamber 140 housing a spring 141 that urges the push rod 132 upwards. A rubber member 142 attached to the upper end of the push rod 132 comes into contact with the other end of the tension arm 130. The spring 141 then urges the tension arm 130 around via the push rod 132 by tensioning the cam chain 127 using the tension sprocket 131. A check valve 143 is provided at the lower part of the push rod 132 and a through-hole 144 is provided at the upper part of the push rod 132 so that oil within the oil sump 137 can pass through the push rod 132. The check valve 143 permits the flow of oil into the oil chamber 140 when the push rod 132 moves upwards due to the spring force of the spring 141 and becomes locked when the push rod 132 is pushed downwards, i.e. the position of the push rod 132 is maintained when a reactive force is received from the rubber chain 127 urged in the direction of tensioning so that the oil chamber 140 is locked. Referring to Fig. 9, a through hole 145 is provided at the left crankcase 35 so that the oil sump 137 is made to communicate with the lower parts within the left and right crankcases 35 and 36. Ribs 147 and 148 are provided at so as to be mutually in contact at the left and right crankcases 35 and 36 and form an oil sump 146 communicating with the through hole 145 between the bottoms of the crankcases 35 and 36. Each rib 147 and 148 is formed in an arc shape so as to come into contact with and be opposite t he outer periphery of the crankshaft 40 and the output gear 93. The upper end of each rib 147 and 148 is arranged at a position substantially corresponding to the bottom wall 142a of the cam chain chamber 142. Also, a throttle hole 149 for causing a bottom part of the oil sump 146 to be connected to the lower part of the operating chamber 106 is provided in the crankcase 35, and a throttle hole 150 for returning oil that has flowed to the crankshaft 40 and the output gear 93 side to a lower part within the operating chamber 106. When the engine E is stopped, oil collects inside the operating chamber 106 up to the Ls shown in Fig. 7, but with operation of the engine E, oil that has scattered as a result of rotation of a rotor 109 becomes collected in the sumps 137 and 146, and return of oil from the sump 146 to the operating chamber 106 is squeezed though the throttle hole 149 which means that when the engine E is operating the oil level changes to a fixed level in the sumps 1 37 and 147 shown by the line Lo, and a portion b of the ring gear 121 that is soaked in the oil becomes small. Referring to Fig. 10, an oil collecting chamber 153 having an inlet 153 for taking in oil that has been scattered by the ring gear 121 inside the operating chamber 106 is formed at an upper part between the crankcase 35 including the case portion 35a and the crankcase cover 105 by bringing ribs 154 and 155 respectively provided in the left crankcase 35 and the crankcase cover 105 into contact with each other. The oil collecting chamber 153 is formed between the left crankcase 35 and the crankcase cover 105 with the inlet 152 arranged so as to receive oil that has been scattered by rotation of the ring gear 121 an moved along the inner surfaces of the left crankcase 35 and the crankcase cover 105. Guide walls 156 and 157 are provided in the left crankcase 35 and the crankcase cover 105 for guiding oil that has moved along these inner surfaces into the inlet 152. Further, the oil collecting chamber 153 is formed so as to be apart from the inlet 152 and slightly lower. Pairs of contacting control walls 161, 162 and 163, 164 are formed in the left crankcase 35 and the crankcase cover 105 so as to rise from the bottom 153a of the oil collecting chamber 153. Using these control walls, the inside of the oil collecting chamber 153 is divided up into a plurality, for example 3, collecting sections 158, 159 and 1 60 that are progressively lower the further they are away from the inlet 152. Each control wall 161, 162, and 163, 164, is formed so as to cause oil to progressively overflow from an uppermost collecting section 158, through a middle collecting section 159 to a lowermost collecting section 160. Also, each of the collecting sections 158, 159 and 160 can supply oil to respectively different sections to be lubricated. A lubricating oilway 165 for supplying oil to parts of the gear trains 98 - 101 and to a start clutch 95 is provided coaxially with a main shaft 96 of a transmission M so as to pass through the collecting section 158, a lubricating oilway 166 for supplying oil to other parts of the gear trains 98 - 101 is provided coaxially with a final shaft 97 of a transmission M so as to pass through the collecting section 159, and a lubricating oilway 167 for supplying oil to the cam shaft 47 is provided in the left crankcase 35 and the crankcase cover 105 so as to pass through the collecting section 160. [0054]- Oil also becomes stirred up between left and right crankcases 35 and 36 by the crankshaft 40 and the output gear 93. As shown by arrow 168 in Fig. 3, the oil is scattered in an upward direction by the crankshaft 40 and the output gear 93, but guide walls 169... for introducing oil that has been scattered upwards as shown by the arrow 168 in between parts of the crankshaft 40 and crankshaft 45 that are to be lubricated are provided in the left and right crankcases 35 and 36, being formed in an annular shape corresponding to the input gear 94, start clutch 95 and each of the gear trains 98 - 101. Oil dropping from the lubricating oilway 165 inside the main shaft 96 via the lubrication sections of the gear trains 98 - 101 is also guided towards the crankshaft 40 and the crankshaft 45 by the guide walls 169... [0055}- Next, the operation of this embodiment will be described. A power unit P is swingable supported on a vehicle frame F via a swing arm 53 connected to the engine body 34 of the engine E. However, the swing arm 53 is swingably connected to the vehicle frame F so as to maintain a gap between the cylinder head 38 of the engine E and a carburetor 74. Because of this, it is possible to extremely effectively prevent detrimental effects due to heat from the cylinder head 38 affecting the carburetor 74 due to the fact that the swing arm 53 exists between the cylinder head 38 and the carburetor 74, and also to extremely effectively prevent lowering of the efficiency of the carburetor 74 due to heat from the cylinder head 38. Further, the swing arm 53 is for swingably supporting the power unit P on the vehicle frame F, there is no need to provide a member specially for preventing the carburetor 74 being adversely affected by heat from the cylinder head 38 and it is possible to avoid increasing the number of components. Also, the carburetor 74 is fixed to the swing arm 53, an intake pipe 82 fixed to the swing arm 53 and linking to the cylinder head 38 passes through the swing arm 53 and is connected the carburetor 74, which means that high strength is not required to support the carburetor 74 on the intake pipe 82 and the intake pipe 82 can be made small in size and light in weight. By supporting the carburetor 74 rigidly with the swing arm 53 it is possible to avoid vibrations of the engine body 34 adversely affecting the carburetor 74 and to prevent the efficiency of the carburetor 74 being lowered due to vibrations. As a result of rotation of the ring gear 121 inside the operating chamber 106, oil inside the operating chamber 106 is stirred and scattered by the ring gear 121 but an oil sump 137 for collecting this scattered oil is formed in the bottom 124a of a cam chain chamber 124 inside of which a cam chain 127 wound around a drive sprocket 125 and a driven sprocket 126 moves, so as to open into an end part of the side of the operating chamber 106. Since the oil sump 137 is linked to the operating chamber 106 through the throttle hole 149, the surface of the oil inside the operating chamber 106 becomes lowered due to some of the oil draining into the oil sump 137 when the engine E is operating, and accordingly it is possible to reduce friction loss due to rotation of the ring gear 121. [0058] - The oil sump 137 can supply oil to an oil chamber 140 caused to face one end of a pushrod 132 having the other end connected to a tension sprocket 131 contacting the cam chain 127, and enables reliable operation of the push rod 132 by gathering oil accumulating in the oil sump 137 when the engine E is operating. An oil collecting chamber 153 having an inlet 152 for receiving oil that has been scattered by rotation of the ring gear 121 within the operating chamber 106 is formed between the left crankcase 35 and the crankcase cover 105, the inside of the oil collecting chamber 153 is divided up into a plurality of collecting sections 158, 159 and 160 that are progressively lower the further they are away from the inlet 152 and are respectively connected to different sections that are to be lubricated. Also, each of control walls 161, 162, and 163, 164, is formed so as to cause oil to progressively overflow from an uppermost collecting section 158, through a middle collecting section 159 to a lowermost collecting section 160. Accordingly, oil that has accumulated inside the oil collecting chamber 153 overflows through the control walls 161 and 162, 163 and 164 inside the oil collecting chamber 153 to progressively drain to the collecting sections 158 - 159 and oil that has drained into the respective oil collecting sections 158 - 159 is supplied to respectively supplied to corresponding sections to be lubricated, which means that it is possible to supply an appropriate amount of oil to each of the sections to be lubricated. An embodiment of the present invention has been described in detail above, but the present invention is not limited to the above described embodiments and various modifications are possible without departing from the scope of the invention as disclosed in the appended claims. For example, the present invention can also be applied to a scooter type motorcycle. [Fv fleets of the Invention] According to the invention as disclosed above, it is possible to reliably operate a push rod by reliably collecting oil that has been scattered by rotation of a rotating member in a sump, and it is possible to reduce friction loss due to rotation of a rotating member. [Description Of The Numerals] 34 engine body 35 crankcase 45 crankshaft 47 cam shaft 105 crankcase cover 106 operating chamber 121 ring gear as a rotating member 124 cam chain chamber 124a bottom 125 drive sprocket 126 driven sprocket 127 cam chain 131 tension sprocket as a tension member 132 push rod 137 oil sump 140 oil chamber 149 throttle hole V motor cycle as a vehicle WE CLAIM: 1. A cam chain tensioner for a vehicle engine in which a crankcase cover (105) is attached to a crankcase (35) of an engine body (34) and defines an operating chamber (106) with the crankcase (35); a drive sprocket (125) and a rotating member (121) having at least a part thereof immersed in oil housed in the operating chamber (106) for the purpose of scattering oil therein are fixedly attached to a crankshaft (40) rotatably supported by the crankcase (35), in the operating chamber (106); a cam chain chamber (124) houses an endless cam chain (127) extending around a driven sprocket (126) fixedly coupled to the drive sprocket (125) and a cam shaft (47), the cam chain (127) being movable in the cam chain chamber (124), and the cam chain chamber (124) has a bottom (124a) thereof positioned above a bottom of the operating chamber (106), is formed in the engine body (34) and extends substantially along the length of a vehicle (V); a push rod (132) having one end thereof connected with a tension member (131) in contact with the cam chain (127) is urged by a spring to operate the tension member (131) which tensions the cam chain (127); an oil sump (137) capable of feeding oil to an oil chamber (140) where the push rod (132) has the other end thereof housed in order to maintain a position thereof against reactive force from the cam chain (127) is provided in the engine body 34 and opens on the bottom (124a) of the cam chain chamber (124), characterized in that: said oil sump (137) is capable of collecting oil scattered in response to the rotation of the rotating member (121) and is provided in the engine body (34) and opens on the bottom (124a) of the cam chain chamber (124) on the side of the operating chamber (106), and communicates with the operating chamber (106) via a throttle hole (149). 2. A cam chain tensioner for a vehicle engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

35-del-1999-claims.pdf

35-del-1999-correspondence-others.pdf

35-del-1999-correspondence-po.pdf

35-del-1999-description (complete).pdf

35-del-1999-drawings.pdf

35-del-1999-form-1.pdf

35-del-1999-form-13.pdf

35-del-1999-form-19.pdf

35-del-1999-form-2.pdf

35-del-1999-form-3.pdf

35-del-1999-form-4.pdf

35-del-1999-form-6.pdf

35-del-1999-gpa.pdf

35-del-1999-petition-138.pdf