Title of Invention	OIL RECOVERY STYSTEM FOR TWO-CYCLE ENGINE
Abstract	An oil recovery system for a two-cycle engine, in which an oil recovery chamber (75) communicated to a bottom of a crank chamber (33) of a two-cycle engine (E) is connected to an intake system (38) of said two-cycle engine (E) via a return pipe line (102), characterized in that i said oil recovery system has a control valve (103) for prohibiting return of oil from said oil recovery chamber (75) to said intake system (38) until the engine state reaches a specific warming state after start-up of said two-cycle engine (E).

Title of Invention

OIL RECOVERY STYSTEM FOR TWO-CYCLE ENGINE

Abstract

An oil recovery system for a two-cycle engine, in which an oil recovery chamber (75) communicated to a bottom of a crank chamber (33) of a two-cycle engine (E) is connected to an intake system (38) of said two-cycle engine (E) via a return pipe line (102), characterized in that i said oil recovery system has a control valve (103) for prohibiting return of oil from said oil recovery chamber (75) to said intake system (38) until the engine state reaches a specific warming state after start-up of said two-cycle engine (E).

Full Text	FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] 'OIL RECOVERY STYSTEM FOR TWO-CYCLE 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 The following specification particularly describes the nature of the invention and the manner in which it is to be performed :- 988/MUM/2000 6 NOV 2000 GRANTED [Detailed Description of the Invention] [0001] [Technical Field to Which the Invention Pertains] The present invention relates to an oil recovery system for a two-cycle engine, in which an oil recovery chamber communicated to a bottom of a crank chamber of a two-cycle engine or a two-cycle engine for a motorcycle is connected to an intake system of the two-cycle engine via a return pipe line. [0002] [Prior Art] It has been known, for example, from Japanese Patent Laid-open No. Hei 5-179920 that in a two-cycle engine, since oil supplied together with air-fuel mixture and oil supplied to a lubrication portion via an oil passage are accumulated on a bottom of a crank chamber, the oil accumulated on the bottom of a crank chamber is recovered by making use of depression at an engine manifold and is returned to an intake system. [0003]. [Problem to be Solved by the Invention] However, in a cold state of a two-cycle engine directly after start-up of the engine, since the engine temperature is low and the heat generation is small, the oil returned to an intake system cannot be perfectly burned, and the unburned oil may be discharged as white smoke together with exhaust gas. To prevent the occurrence of such white smoke, the oil recovery system disclosed in the above-described document is configured such that a return pipe line is connected to a portion, on the upstream side from a throttle valve, of an intake system. In such a system, since the depression at an engine manifold is low directly after start-up of the engine, the return of oil to the intake system can be prevented by provision of a check valve, to thereby prevent the occurrence of white smoke; however, if a snapping operation is performed directly after start-up of the two-cycle engine, oil is returned to the intake system, to cause white smoke. [0004] In view of the foregoing, the present invention has been made> and- a first object of the present invention is to provide an oil recovery system for a two-cycle engine, which is capable of certainly preventing the occurrence -of white smoke even by a snapping operation directly after start-up of the engine. [0005] Further, in the above-described prior art two-cycle engine, a pressure loss may occur in the crank chamber due to the depression at an engine manifold when the oil is returned to the intake system side, which leads to degradation of the engine performance. Also oil may counter-flow from an oil recovery chamber to the crank chamber side due to pressure pulsation of the crank chamber, vibration from a road surface upon running of a motorcycle, and vibration of the engine, which leads to degradation of the engine recovery performance. [0006] In view of the foregoing, the present invention has been made, and a second object of the present invention is to provide an oil recovery system for a two-cycle engine of a motorcycle, which is capable of improving the oil recovery performance while avoiding the degradation of the engine performance due to a pressure loss in a crank chamber. [0007] [Means for Solving the Problem] To achieve the above first object, according an invention described, there is provided an oil recovery system for a two-cycle engine, in which an oil recovery chamber communicated to a bottom of a crank chamber of a two-cycle engine (E) is connected to an intake system of said two-cycle engine (E) via a return pipe line, characterized in that said oil recovery system has a control valve for prohibiting return of oil from said oil recovery chamber to said intake system until the engine state reaches a specific warming state after start-up of the two-cycle engine. With this configuration of the invention as described since the return of oil from the oil recovery chamber to the intake system is prohibited by the control valve until the engine state reaches the specific warming state directly after start-up of the two-cycle engine, oil is not returned to the intake system even by a snapping operation before the engine state reaches the warming state, with a result that it is possible to certainly prevent the occurrence of white smoke. According to the invention described, the control valve is an electromagnetic switching valve operated to alternatively switch the communication state of a first port connected to the oil recovery chamber, a second port connected to the intake system, and a third port, between a state in which the first port is communicated to the second port and a state in which the first port is communicated to the third port; and an open pipe line with its one end connected to the third port is raised upwardly from the control valve, and the other end of the open pipe line is opened to atmospheric air. With this configuration, in the state in which the return of oil to the intake system is prohibited by cutting off the communication between the first and second ports and allowing the communication between the first and third ports and, the oil recover chamber does not become an enclosed state, with a result that the recovery of oil from the crank chamber to the oil recovery chamber can be desirably performed. Further, since the open pipe line communicated to the third port is raised upwardly from the control valve, it is possible to prevent oil from flowing on the open pipe line side. According to an invention, the oil recovery chamber ts connected to a portion, positioned between a throttle valve and a reed valve, of the intake system via the return pipe line. With this configuration, it is possible to prevent oil returned to the intake system from adhering on the throttle valve and hence to improve the workability of the throttle valve, and to promote atomization of return oil supplied to the crank chamber side by action of the reed valve and hence to improve the combustibility of oil and more effectively prevent the occurrence of white smoke. According to an invention , the specific warming state is set at a state in which catalyst in a catalyst device provided in an exhaust system of the two-cycle engine E is activated. With this configuration, it is possible to prevent oil from adhering on the catalyst, and hence to promote the activation of the catalyst and more effectively prevent the occurrence of white smoke. To achieve the above second object, there is provided an oil recovery system for a two-cycle engine of a motorcycle, in which an oil recovery chamber disposed under a crank chamber of a two-cycle engine mounted on a motorcycle and communicated to a bottom of the crank chamber is formed in an oil recovery tank supported by the engine and the oil recovery chamber is connected to an intake system of the engine, characterized in that the oil recovery tank is provided with a partition wall for partitioning the inside of the oil recovery chamber into an upper chamber communicated to the bottom of the crank chamber and a lower chamber connected to the intake system; the partition wall is formed into a funnel shape which allows the flow area of oil to be reduced toward the lower side; and a communication hole for communicating the upper chamber to the lower chamber is provided at the lowermost end of the partition wall. [0013] With this configuration, oil led from the crank chamber into the oil recovery chamber flows from the upper chamber to the lower chamber through the communication hole. In this case, since the partition wall is formed into the funnel shape, the diameter of the communication -hole can be set at a "relatively small" value. As a result, it is possible to enhance the efficiency of recovery of oil from the crank chamber, by setting the flow areas of the connecting pipe and the oil lead pipe, which connect the crank chamber to the oil recovery chamber, at relatively large values while suppressing the pressure loss in the crank chamber accompanied by the return of oil to the intake system side by depression at an engine manifold thereby preventing the reduction in engine performance. Further, since the amount of oil, which counter-flows from the oil recovery chamber to the crank chamber side due to pressure pulsation of the crank chamber, vibration from a running road surface, and vibration of the engine, can be minimized by the partition wall and the communication hole, it is possible to further enhance the efficiency of oil recovery. According to the invention, one end of an oil lead pipe is connected to the bottom of the crank chamber at a position which becomes the lowermost end in the tilting state of the body of the motorcycle when a side stand is kept in the working state and the other end of the oil lead pipe is connected to the upper chamber. With this configuration, it is possible to effectively recover oil from the crank chamber by making use of the tilting of the body of the motorcycle in the state in which the body is tilted when the side stand is kept in the working state. [Mode for Carrying out the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. [Brief Description of the Drawings] [Fig. 1] A side view of a motorcycle. [Fig. 2] A side view of a two-cycle engine, with parts partially broken away. [Fig. 3] An enlarged sectional view taken on line 3-3 of Fig 2, in which a side stand is kept in a working state. [Fig. 4] A vertical side view of an exhaust system, with parts partially broken away. [Fig. 5] An enlarged sectional view taken on line 5-5 of Fig 3. [Fig. 6] A side view of an oil recovery tank, with parts partially broken away. [Fig. 7] A front view seen along the direction shown by an arrow 7 of Fig. 6, with parts partially broken away. [0016] Figs. 1 to 7 shows one embodiment of the present invention, wherein Fig. 1 is a side view of a motorcycle; Fig. 2 is a side view of a two-cycle engine with parts partially cutaway; Fig. 3 is an enlarged sectional view taken on line 3-3 of Fig. 2, in which a side stand is kept in a working state; Fig. 4 is a vertical side view of an exhaust system, with parts partially cutaway; Fig. 5 is an enlarged sectional view taken on line 5-5 of Fig. 3; Fig. 6 is a side view, with parts partially cutaway, of an oil recovery tank; and fig. 7 is a front view seen along the direction shown by an arrow 7 of Fig. 6, with parts partially broken away. [,0 017] Referring first to Fig. 1, a head pipe 13 for" steerably supporting a front fork 12 is provided on a front end of a main frame 11 of a body frame F of the motorcycle according to the embodiment of the present invention. A front wheel WF is rotatably supported by lower ends of the front fork 12, and a steering handlebar 14 is connected to an upper end of the front fork 12. [0018] Front ends of a pair of right and left seat rails 15 extending rearwardly, upwardly are connected to an intermediate portion of the main frame 11. Front ends of a pair of right and left stays 16 extending rearwardly, upwardly while being located under the seat rails 15 are connected to a rear end portion of the main frame 11. A fuel tank 17 is supported on a front portion of the main frame 11 and front portions of both the seat rails 15, and a seat 18 is provided on both the seat rails 15. [0019] A two-cycle engine E is mounted on the main frame 11 at a position under the fuel tank 17. A front end of a rear fork 19 extending rearwardly is swingably supported by a rear portion of the main frame 11. A rear wheel WR to be rotated by an output from the engine E is rotatably supported by rear ends of the rear fork 19. A cushion unit 20--is provided between the stay's~16 and'the rear-fork 19. [0020] . A side stand 21, which is turnable between a working position and a storage position, is provided at a lower end of a rear portion of the main frame 11. As shown in Fig. 1, when the side stand 21 at the working position is grounded on a road surface, a body of the motorcycle is tilted leftwardly while being directed forwardly in the running direction. [0021] Referring to Figs. 2 and 3, the two-cycle engine E includes a cylinder block 22, a cylinder head 23 connected to the cylinder block 22, and a crank case 24 connected to the cylinder block 22. A piston 26 slidably fitted in a cylinder bore 25 provided in the cylinder block 22 is connected, via a connecting rod 29 and a crank pin 30, to a crank shaft 28 rotatably supported by the crank case 24. [0022] A combustion chamber 31, to which the top of the piston 26 faces, is formed between the cylinder block 22 and the cylinder head 23. An ignition plug 32 is mounted in the cylinder head 23 in such a manner as to face to a central-portion of the combustion chamber 311 Scavenging ports 34, which can Communicate a crank chamber 33 formed in the crank case 24 to the combustion chamber 31 by downward movement of the piston 26, are provided in the cylinder block 22 and the crank case 24. An exhaust port 35, which can be communicated to the combustion chamber 31 by downward movement of the piston 26, is provided in the cylinder block 22. An intake port 36 is provided in the crank case 24 in such a manner as to be opened to the crank chamber 33. [0023] A reed valve 37 is mounted in the crank case 24 in such a manner as to be disposed in the intake port 36. An intake system 38, which is communicated to the inside of the crank chamber 33 when the reed valve 37 is opened, is connected to the intake port 36. The intake system 38 includes an air cleaner 40 in which a cleaner element 39 is housed, a carburetor 42 having a throttle valve 41 and connected to the air cleaner 40, and an intake pipe 43 for connecting the carburetor 42 to the intake port 36. A downstream end of the intake pipe 43 is fastened, together with the reed valve 37, to the crank case 24 by means of a plurality of bolts 44. A lower end of a branch pipe 45 extending upwardly is connected to an intermed-i-ate portion of the intake pipe 43, and a cn'amber 46 for reducing intaRe noise is connected to an upper end of the branch pipe 45. ., [0024] An exhaust system 47 connected to the exhaust port 35 includes an exhaust pipe 48 extending from the exhaust port 35, passing under the two-cycle engine E, and further extending up to the right side of the rear wheel WR; and an exhaust muffler 49 connected to a downstream end of the exhaust pipe 48. [0025] Referring to Fig. 4, a catalyst device 50 is housed at a halfway point in the exhaust pipe 48. The catalyst device 50 is configured such that catalyst is supported on the surface of a punching pipe 51 fixed on the inner surface of the exhaust pipe 48 via a plurality of mounting members 52. [0026] Referring particularly to Fig. 5, one end of the crank shaft 28 projects in a transmission chamber 53 partitioned from the crank chamber 33. The transmission chamber 53 is formed by the crank case 24 and a transmission case 54 connected to the crank case 24. Oil is accumulated in the transmission chamber 53 up to a liquid level L- shown in Fig. 5. [0027] The transmission chamber 53 houses a multi-stage transmission 57 composed of a plurality of stages of gear trains allowed to be alternatively meshed. The transmission 57 is positioned between a main shaft 55 and a counter shaft 56. The main shaft 55 has an axial line parallel to that of the crank shaft 28 and is rotatably supported by the transmission case 54, and the counter shaft 56 has an axial line parallel to that of the main shaft 55 and is rotatably supported by the transmission case 54. A power is transmitted from one end, projecting from the transmission case 54, of the counter shaft 56 to the rear wheel WR via a drive chain 58 (see Fig. 1). A drive gear 59 is fixed to one end of the crank shaft 28, and a power is inputted from the drive gear 59 to the main shaft 55. [0028] The other end of the crank shaft 28 projects in an auxiliary chamber 60 partitioned from the crank chamber 33 and the transmission chamber 53, and a generator is connected to the other end of the crank shaft 2 8 in the auxiliary chamber 60. [0029] At- the boundary between the crank chamber 33 'and the transmission chamber 53, a first oil seal 61 and a first ball bearing 62 offset to the transmission chamber 53 side from the first oil seal 61 are provided between the crank shaft 28 and the crank case 24. At the boundary between the crank chamber 33 and the auxiliary chamber 60, a second oil seal 63, a third oil seal 64 offset to the auxiliary chamber 60 side from the second oil seal 63, and a second ball bearing 65 positioned between the second and third oil seals 63 and 64 are provided between the crank shaft 28 and the crank case 24. [0030] An oil-tight space 66 is formed between the second and third oil seals 63 and 64 in the crank case 24. In the oil-tight space 66, a drive screw gear 67 is provided on the crank shaft 28, and a driven screw gear 68 having an axial line perpendicular to an axial line of the crank shaft 28 is meshed with the drive screw gear 67. The driven screw gear 68 is connected to an oil pump (not shown), and the oil pump is driven by the crank shaft 28. [0031] A mission gear 69, which constitutes part of the transmission 57, is rotated in the direction shown by an arrow in Fig. 5, with its outer periphery being in proximity to a- plane, facing to the'" transmission chamber 53, of the crank case" 24. Oil in the transmission chamber 53 is splashed up by the mission gear ^69. Meanwhile, the-crank case 24 has an oil receiving portion 70 integrally projecting from a portion over the mission gear 69 into the transmission chamber 53. The oil receiving portion 70 is allowed to receive part of oil splashed up by the mission gear 69. [0032] The crank case 24 has an oil supply hole 71 with its one end opened to the transmission chamber 53 and the other end opened to the oil-tight space 66, and an oil discharge hole 72 with its one end opened to the oil-tight space 66 and the other end opened to an inner bottom of the transmission chamber 53. A lower edge of the one end, opened to the transmission chamber 53, of the oil supply hole 71 is formed in such a manner as to be continuous to the upper surface of the oil receiving portion 70. [0033] By the way, the oil supply hole 71 is formed in the crank case 24 in such a manner as to have an axial line parallel to the bolts 44 screwed in the crank case 24 for fastening the reed valve 37 to the crank case 24, and an opening-provided in the crank case 24""at a position" separated from the one end of the oil supply hole 71 is blocked, with a blocking member 73. An^ opening provided i-n the crank case 24 at a position separated from the other end, opened to the bottom of the transmission chamber 53, of the oil discharge hole 72 is also blocked with a blocking member 74. [0034] The other end of the oil supply hole 71 is opened to the oil-tight space 66 at a position between the second oil seal 63 and the second ball bearing 65, and the one end of the oil discharge hole 72 is opened to the oil-tight space 66 at a position between the third oil seal 64 and the second ball bearing 65. That is to say, the other end of the oil supply hole 71 and the one end of the oil discharge hole 72 are opened in the oil-tight space 66 at the positions between which the second ball bearing 65 is put. [0035] Oil supplied together with air-fuel mixture, and oil supplied to a lubrication portion of the engine E are accumulated on the inner bottom of the crank chamber 33, and the oil thus accumulated is recovered from the crank chamber 33 and returned to the intake system 38. To recover -such oil, an oil recovery tank '7 6 including'an oil recover chamber 75 communicated to the bottom of the crank chamber 33 is disposed under the two-cycle engine E [0036] Referring particularly to Fig. 6, the oil recovery tank 76 includes a tank main body 77, and a cover plate 78 fastened to a side surface of the tank main body 77 by means of a plurality of, for example, four bolts 79. The tank main body 77 is integrally provided with two supporting arms 80 and 81 extending upwardly, and upper ends of the supporting arms 80 and 81 are fastened to the crank case 24 of the two-cycle engine E. In this way, the oil recovery tank 76 is supported by the two-cycle engine E in such a manner as to be disposed under the engine E. [0037] The oil recovery chamber 75 is formed by closing an opening end of a circular recess provided in the tank main body 77 with the cover plate 78. An annular seal member 82 surrounding the recess is interposed between the tank main body 77 and the cover plate 78. [0038] The oil recovery chamber 75 is partitioned into an upper chamber 75a and a lower chamber 75b by means of a partition wall 83 provided on the tank main body 77. The partition wall- 83 is formed into a funnel shape which allows the flow area "of oil to be reduced toward the lower side. A communication hole 84 for communicating the-upper chamber 75a to the lower chamber 75b is provided at the lowermost end of the partition wall 83. To be more specific, when the motorcycle is parked with the side stand 21 kept in the working state, the body of the motorcycle is, as shown in Fig. 3, tilted sideways from the vertical direction by an angle a , and the communication hole 84 is provided in the partition wall 83 r typicallyr at an end on the cover plate 18 side in such a manner that the communication hole 84 is located at the lowermost end of the partition wall 83 in the above tilting state of the body of the motorcycle. [0039] A connection pipe 85 communicated to the inner bottom of the crank chamber 33 is mounted to the crank case 24 at a position which becomes the lowermost end in the tilting state of the body of the motorcycle when the side stand 21 is kept in the working state. One end of an oil lead pipe 86 is connected to the connection pipe 85, and the other end of the oil lead pipe 86 is connected to the upper chamber 7 5a. . [0040] Referring particularly to Fig 7, a cover 88 is fastened to the tank main body 77 of the oil recovery tank 76. with a partition plate 87 put ./between the cover -88 and the tank main body 77 by means of a plurality of, for example, four bolts 89. An inlet chamber 91, which is communicated to the lower chamber 75b of the oil recovery chamber 75 via a passage 90 provided in the tank main body 77, is formed between the tank main body 77 and the partition plate 87, and an outlet chamber 92 is formed between the partition plate 87 and the cover 88. A seal member 93 surrounding the inlet chamber 91 is interposed between the tank main body 77 and the partition plate 87, and a seal member 94 surrounding the outlet chamber 92 is interposed between the partition plate 87 and the cover 88. [0041] A check valve 95 is disposed in an upper portion of the partition plate 87. The check valve 95 includes a holding cylinder 97 pressed in a mounting hole 96 and a disk-shaped valve body 98 housed in the holding cylinder 97. The mounting hole 96 is formed in the upper portion of the partition plate 87 in such a manner as to communicate the inlet chamber 91 to the outlet chamber 92 [0042] The holding cylinder 97 with its bottom close'd is pressed in the mounting hole 96 with its closed bottom disposed on the inlet chamber 91 side, A valve hole 99 i inwardly therefrom. [0043] The check valve 95 allows the flow of oil from the inlet chamber 91 side to the outlet chamber 92 side, but prohibits the flow of oil from the outlet chamber 92 side to the inlet chamber 91 side. [0044] Referring particularly to Fig. 2, a connection pipe 101 is mounted to a portion, corresponding to the check valve 95, of the cover 88. One end of a return pipe line 102 is connected to the connection pipe 101, and the other end of the return pipe line 102 is connected to the intake system -38. A control valve 103 is provided at a halfway point of the return pipe line 102. [0045] . The control valve 103 is an electromagnetic switching valve having first, second and third ports 104, 105 and 106. The control valve 103 can switch a communication state of the first, second and third ports 104, 105 and 106 from or to a state in which the first port 104 is communicated to the second port 105 and is cutoff from the third port 106 to or from a state in which the first port 1Q4 is communicated to the third port 106 and is cutoff from the second port 105. [0046] The return pipe line 102 includes a first pipe line portion 102a and a second pipe line portion 102b. One end of the first pipe line portion 102a is connected to the connection pipe 101, and the other end of the first pipe line portion 102a is connected to the first port 104 of the control valve 103. One end of the second pipe line portion 102b is connected to the second port 105 of the control valve 103, and the other end of the second pipe line portion 102b is connected to a portion, located between the throttle valve 41 and the reed valve 37 of the intake system 38, that is, the intake pipe 43. [0047] One end of an 'open pipe line 107 raised upwardly from the control valve 103 is connected to the third port 106 of the control valve 103. The other end of the open pipe line 107 is opened to atmospheric air on the upstream side from the cleaner element 39 in the air cleaner 40. [0048] The control valve 103 is controlled by control means (not shown) as follows: namely, in a period until the engine state reaches a specific warming state after start-up of the two-cycle engine E and in the stoppage state of the two-cycle engine E, the control valve 103 switches the communication state of the ports 104, 105 and 106 into the state in which the first port 104 is communicated to the third port 106 and is cutoff from the second port 105 in order to prohibit the return of oil from the oil recovery chamber 75 to the intake system 38; and after the engine state reaches the specific warming state, the control valve 103 switches the communication state of the ports 104, 105 and 106 into the state in which the first port 104 is communicated to the second port 105 and is cutoff from the third port 106. [0049] That is to say, in the period until the engine state reaches the specific warming state after start-up of the two-cycle engine E and in the stoppage state of the two-cycle engine E, the return pipe line 102 is cutoff so that the oil recovery chamber 75 is connected to the inside of the air cleaner 40 via the check valve 95. [0050] The above-described specific warming state is set as a state in which catalyst in the catalyst device 50 provided in the exhaust system 47 of the two-cycle engine E is activated. The activation of catalyst is decided by detecting the temperature in the inside of the catalyst device 50, or decided on the basis of a condition that a state in which the number of revolution of the two-cycle engine E is a setting number of revolution (for example, 3000 rpm) or more is continued for a setting time (for example, one minute) or more. [0051] The function of this embodiment will be described below. At the boundary between the crank chamber 33 and the auxiliary chamber -60, the second and third oil seals 63 and 64 are provided between the crank case 24 and the crank shaft 28 so that the oil-tight space 66 is formed between- the oil seals 63 and 64 in the crank case 24', and the second ball bearing 65 provided between the crank case 24. and the crank shaft 28 is hous-ed in the oil--tight space 66. To lubricate the second ball bearing 65, the oil receiving portion 70 capable of receiving oil in the transmission chamber 53 splashed up by the mission gear 69 is integrally provided on a portion, positioned over the mission gear 70, of the crank case 24. The oil supply hole 71 with its one end opened to the transmission chamber 53 and the other end opened to the oil-tight space 66 is provided in the crank case 24 in such a manner that the lower edge of the one end, opened to the transmission chamber 53, of the oil supply hole 71 is continuous to the upper surface of the oil receiving portion 70. The oil discharge hole 72 with its one end opened to the oil-tight space 66 and the other end opened on the lower bottom of the transmission chamber 53 is also provided in the crank case 24. [0052] Accordingly, oil splashed by the mission gear 69 in the transmission chamber 53 is supplied from the oil receiving portion 70 into the oil-tight space 66 via the oil supply hole 71 to lubricate the second ball bearing 65, and the oil is returned from the oil-tight space 66 into the—transmission chamber 53 via ttie oil discharge hole 72. Such a structure for lubricating the second ball bearing 65 can be obtained only by forming the oil -supply hole 71 and the oil discharge hole 72 in the crank case 24. The simple lubricating structure is advantageous in reducing the number of the machining steps as compared with the conventional lubricating structure in which an oil passage is formed in the crank shaft 28. [0053] Since the other end of the oil supply hole 71 and the one end of the oil discharge hole 7 2 are opened in the oil-tight space 66 at the positions between which the second ball bearing 65 is put, oil flows in the oil-tight space 66 while necessarily passing through the second ball bearing 65. As a result,.the second ball bearing 65 is certainly lubricated with oil flowing in the oil-tight space 66. [0054] Since the oil supply hole 71 is provided in the crank case 24 in such a manner as to have the axial line parallel to the bolts 44 screwed in the crank case 24 for fastening the reed valve 37 to the crank case 24, the oil supply hole 71 and the threaded holes in which the bolts 44 are to be screwed can be formed in the crank case 24 in the same direction. As a result, is possible to form the oil supply hole 71 with good machinability and productivity. J - [0055] To recover oil accumulated on the lower bottom of the crank chamber 3 3 from the crank chamber 3 3 and to return the oil to the intake system 38, the oil recovery tank 76 including the oil recovery chamber 75 communicated to the bottom of the crank chamber 33 is disposed under the two-cycle engine E. The oil recovery tank 76 has the partition wall 83 for partitioning the inside of the oil recovery chamber 75 into the upper chamber 75a communicated to the bottom of the crank chamber 33 and the lower chamber 75b connected to the intake system 38. The partition wall 83 is formed into the funnel shape which allows the flow area of oil to be reduced toward the lower side. The communication hole 84 for communicating the upper chamber 75a to the lower chamber 75b is provided at the lowermost end of the partition wall 83. [0056] Accordingly, oil led from the crank chamber 33 into the oil recovery chamber 75 flows from the upper chamber 75a to the lower chamber 75b through the communication hole 84-. —Further, since the partition wall 83 is formed into the funnel shape, the diameter of the communication hole 84. can be set at a relatively small value. As-a result, it is possible to enhance the efficiency of recovery of oil from the crank chamber 33 by setting the flow areas of the connecting pipe 85 and the oil lead pipe 86, which connect the crank chamber 33 to the oil recovery chamber 75, at relatively large values while suppressing the pressure loss in the crank chamber 33 accompanied by the return of oil to the intake system 38 side by depression at an engine manifold thereby preventing the reduction in engine performance. Further, since the amount of oil, which counter-flows from the oil recovery chamber 75 to the crank chamber 33 side due to pressure pulsation of the crank chamber 33, vibration from a running road surface, and vibration of the engine E, can be minimized by the partition wall 83 and the communication hole 84, it is possible to further enhance the efficiency of oil recovery. [0057] Since the one end of the oil lead pipe 86 is connected to the lower bottom of the crank chamber 33 at a position which becomes the lowermost end in the tilting state of the body of the motorcycle when the side stand 21 is kept in -the working state and" the other end of' the oil lead pipe 86 is connected to the upper chamber 75a, it is possible to effectively recover .oil from the-crank - • chamber 33 by making use of the tilting of the body of the motorcycle in the state in which the body is tilted when the side stand 21 is kept in the working state. [0058] The control valve 103 for prohibiting the return of oil from the oil recovery chamber 75 to the intake system 38 until the engine state reaches the specific warming state after start-up of the two-cycle engine E is provided at a halfway point of the return pipe line 102 for returning the oil recovered to the oil recovery chamber 75 to the intake system 38. Accordingly, even by performing a snapping operation before the engine state reaches the warming state, the oil is not returned to the intake system 38, with a result that it is possible to certainly prevent the occurrence of while smoke. [0059] The control valve 103 is the electromagnetic switching valve operated to alternatively switch, the communication state of the first port 104 connected to the oil recovery chamber 75 via the check valve 95, the second port 105 connected to the intake system 38, and the third port- 106, between the state"" in which the first port 104 is communicated to the second port 105 and the state in which the first port 104 is communicated to the third port 106. The open pipe line 107 with its one end connected to the third port 106 is raised upwardly from the control valve 103, and the other end of the open pipe line 107 is opened to atmospheric air in the air cleaner 40. [0060] Accordingly, in the state in which the return of oil to the intake system 38 is prohibited by cutting off the communication between the first and second ports 104 and 105 and allowing the communication between the first and third ports 104 and 106, the oil recover chamber 75 does not become an enclosed state, with a result that the recovery of oil from the crank chamber 33 to the oil recovery chamber 75 can be desirably performed. Further, since the open pipe line 107 communicated to the third port 106 is raised upwardly from the control valve 103, it is possible to prevent oil from flowing on the open pipe line 107 side. [0061] Since the oil recovery chamber 75 is connected to a portion, positioned between the throttle valve 39 and the reed valve 37,- of the intake system'" 3B via the return pipe line 102, it is'possible to prevent oil returned to the intake system 3 8 from adhering on the throttle -valve 39 and hence to improve the workability of the throttle valve 39, and to promote atomization of return oil supplied to the crank chamber 33 side by action of the reed valve 37 and hence to improve the combustibility of oil and more effectively prevent the occurrence of white smoke. [0062] Since the specific warming state is set as the state in which catalyst in the catalyst device 50 provided in the exhaust system 47 of the two-cycle engine E is activated, it is possible to prevent oil from adhering on the catalyst, and hence to promote the activation of the catalyst and more effectively prevent the occurrence of white smoke. [0063] 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 present invention described in claims. [0064] For example, although the control valve 103 is provided at a halfway point of the return pipe line 102 in the embodiment, it may. be mounted an the oil recovery tank 76. [0065] [Effect of the Invention] According to the invention since the return of oil from the oil recovery chamber to the intake system is prohibited by the control valve until the engine state reaches the specific warming state directly after start-up of the two-cycle engine, oil is not returned to the intake system even by a snapping operation before the engine state reaches the warming state, with a result that it is possible to certainly prevent the occurrence of white smoke. [0066] According to the invention since the oil recover chamber does not become an enclosed state in the state in which the return of oil to the intake system is prohibit, the recovery of oil from the crank chamber to the oil recovery chamber can be desirably performed. Further, it is possible to prevent oil from flowing on the open pipe line side. [0067] According to the invention described is possible to prevent oil returned to the intake system from adhering on the throttle valve and hence to improve the workability of the throttle valve, and to promote atomization of return oil supplied to the crank chamber side by action of the reed valve and hence to improve the combustibility of oil and more effectively prevent the occurrence of white smoke. [0068] According to the invention described it is possible to prevent oil from adhering on the catalyst, and hence to promote the activation of the catalyst and more effectively prevent the occurrence of white smoke. [0069] According to the invention described it is possible to enhance the efficiency of recovery of oil from the crank chamber by setting the flow areas of the connecting pipe and the oil lead pipe, which connect the crank chamber to the oil recovery chamber, at relatively large values while suppressing the pressure loss in the crank chamber accompanied by the return of oil to the intake system side by depression at an engine manifold thereby preventing the reduction in engine performance. Further, since the amount of oil, which counter - flows from the—oil recovery chamber to the crank chamber side due to pressure pulsation of the crank chamber, vibration from a running road surface, and vibration of the engine, can be minimized by the partition wall and the communication hole, it is possible to further enhance the efficiency of oil recovery. [0070] According to the invention described it is possible to effectively recover oil from the crank chamber by making use of the tilting of the body of the motorcycle in the state in which the body is tilted when the side stand is kept in the working state. [Explanation of Characters] 21: side stand, 33: crank chamber, 37: reed valve, 38: intake system, 41: throttle valve, 47: exhaust system, 50: catalyst device, 75: oil recovery chamber, 75a: upper chamber, 75b: lower chamber, 76: oil recovery tank, 83: partition wall, 84: communication hole, 86: oil lead pipe 102: return pipe line, 103: control valve, 104: first port, 105: second port, 106: third port, 107: open pipe line, E: two-cycle engine WE CLAIM: 1. An oil recovery system for a two-cycle engine, in which an oil recovery chamber (75) communicated to a bottom of a crank chamber (33) of a two-cycle engine (E) is connected to an intake system (38) of said two-cycle engine (E) via a return pipe line (102), characterized in that i said oil recovery system has a control valve (103) for prohibiting return of oil from said oil recovery chamber (75) to said intake system (38) until the engine state reaches a specific warming state after start-up of said two-cycle engine (E). 2. An oil recovery system for a two-cycle engine as claimed in claim 1, wherein said control valve (103) is an electromagnetic switching valve operated to alternatively switch the communication state of a first port (104) connected to said oil recovery chamber (75) , a second port (105) connected to said intake system (38), and a third port (106), between a state in which said first port (104) is communicated to said second port (105) and a state in which said first port (104) is communicated to said third port (106) ; and an open pipe line (107) with its one end connected to said third port (106) is raised upwardly from said control valve (103) , and the other end of said open pipe line (107) is opened to atmospheric air. 3. An oil recovery system for a two-cycle engine as claimed in claim 1, wherein said oil recovery chamber (75) is connected to a portion, positioned between a throttle valve (41) and a reed valve (37) , of said intake system (38) via said return pipe line (102). 4. An oil recovery system for a two-cycle engine as claimed in claim 1, wherein said specific warming state is set at a state in which catalyst in a catalyst device (50) provided in an exhaust system (47) of said two- cycle engine (E) is activated. 5. An oil recovery system for a two-cycle engine of a motorcycle as claimed in claim 1, in which an oil recovery chamber (75) disposed under a crank chamber (33) of a two-cycle engine (E) mounted on a motorcycle and communicated to a bottom of said crank chamber (33) is formed in an oil recovery tank (76) supported by said engine (E) and said oil recovery chamber (75) is connected to an intake system (38) of said engine (E), wherein said oil recovery tank (76) is provided with a partition wall (83) for partitioning the inside of said oil recovery chamber (75) into an upper chamber (75a) communicated to the bottom of said crank chamber (33) and a lower chamber (75b) connected to said intake system (38); said partition wall (83) is formed into a funnel shape which allows the flow area of oil to be reduced toward the lower side; and a communication hole (84) for communicating said upper chamber (75a) to said lower chamber (75b) is provided at the lowermost end of said partition wall (83). 6. An oil recovery system for a two-cycle engine of a motorcycle as claimed in claim 5 wherein one end of an oil lead pipe (86) is connected to the bottom of said crank chamber (33) at a position which, becomes the lowermost end in the tilting state of the body of said motorcycle when a side stand (21) is kept in the working state and the other end of said oil lead pipe (86) is connected to said upper chamber (75a). 7. An oil recovery system for a two-cycle engine substantially as hereinbefore described with reference to the accompanying drawings. Dated this 6th day of November, 2000 [RITUSHKA NEGI] OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Full Text

FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
COMPLETE SPECIFICATION
[See Section 10]
'OIL RECOVERY STYSTEM FOR TWO-CYCLE 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
The following specification particularly describes the nature of the invention and the manner in which it is to be performed :-
988/MUM/2000
6 NOV 2000 GRANTED

[Detailed Description of the Invention] [0001]
[Technical Field to Which the Invention Pertains]
The present invention relates to an oil recovery system for a two-cycle engine, in which an oil recovery

chamber communicated to a bottom of a crank chamber of a two-cycle engine or a two-cycle engine for a motorcycle is connected to an intake system of the two-cycle engine via a return pipe line. [0002]
[Prior Art]
It has been known, for example, from Japanese
Patent Laid-open No. Hei 5-179920 that in a two-cycle
engine, since oil supplied together with air-fuel mixture
and oil supplied to a lubrication portion via an oil
passage are accumulated on a bottom of a crank chamber,
the oil accumulated on the bottom of a crank chamber is
recovered by making use of depression at an engine
manifold and is returned to an intake system.
[0003].
[Problem to be Solved by the Invention]
However, in a cold state of a two-cycle engine directly after start-up of the engine, since the engine temperature is low and the heat generation is small, the oil returned to an intake system cannot be perfectly burned, and the unburned oil may be discharged as white smoke together with exhaust gas. To prevent the occurrence of such white smoke, the oil recovery system disclosed in the above-described document is configured

such that a return pipe line is connected to a portion, on the upstream side from a throttle valve, of an intake system. In such a system, since the depression at an engine manifold is low directly after start-up of the engine, the return of oil to the intake system can be prevented by provision of a check valve, to thereby prevent the occurrence of white smoke; however, if a snapping operation is performed directly after start-up of the two-cycle engine, oil is returned to the intake system, to cause white smoke. [0004]
In view of the foregoing, the present invention has been made> and- a first object of the present invention is to provide an oil recovery system for a two-cycle engine, which is capable of certainly preventing the occurrence -of white smoke even by a snapping operation directly after start-up of the engine. [0005]
Further, in the above-described prior art two-cycle engine, a pressure loss may occur in the crank chamber due to the depression at an engine manifold when the oil is returned to the intake system side, which leads to degradation of the engine performance. Also oil may counter-flow from an oil recovery chamber to the crank

chamber side due to pressure pulsation of the crank chamber, vibration from a road surface upon running of a motorcycle, and vibration of the engine, which leads to degradation of the engine recovery performance. [0006]
In view of the foregoing, the present invention has been made, and a second object of the present invention is to provide an oil recovery system for a two-cycle engine of a motorcycle, which is capable of improving the oil recovery performance while avoiding the degradation of the engine performance due to a pressure loss in a crank chamber. [0007]
[Means for Solving the Problem]
To achieve the above first object, according an invention described, there is provided an oil recovery system for a two-cycle engine, in which an oil recovery chamber communicated to a bottom of a crank chamber of a two-cycle engine (E) is connected to an intake system of said two-cycle engine (E) via a return pipe line, characterized in that
said oil recovery system has a control valve for prohibiting return of oil from said oil recovery chamber to said intake system until the engine state reaches a specific warming state after start-up of

the two-cycle engine.
With this configuration of the invention as described since the return of oil from the oil recovery chamber to the intake system is prohibited by the control valve until the engine state reaches the specific warming state directly after start-up of the two-cycle engine, oil is not returned to the intake system even by a snapping operation before the engine state reaches the warming state, with a result that it is possible to certainly prevent the occurrence of white smoke.
According to the invention described, the control valve is an electromagnetic switching valve operated to alternatively switch the communication state of a first port connected to the oil recovery chamber, a second port connected to the intake system, and a third port, between a state in which the first port is communicated to the second port and a state in which the first port is communicated to the third port; and an open pipe line with its one end connected to the third port is raised upwardly from the control valve, and the other end of the open pipe line is opened to atmospheric air. With this configuration, in the state in which the return of oil to the intake system is prohibited by cutting off the communication between the first and second ports and allowing the communication between the first and third ports and, the oil recover chamber does not become an enclosed state, with a result that the recovery of oil from the crank chamber to the oil recovery chamber can be desirably performed. Further, since the open pipe line communicated to the third port is raised upwardly from the control valve, it is possible to prevent oil from flowing on the open pipe line side.

According to an invention, the oil recovery chamber ts connected to a portion, positioned between a throttle valve and a reed valve, of the intake system via the return pipe line. With this configuration, it is possible to prevent oil returned to the intake system from adhering on the throttle valve and hence to improve the workability of the throttle valve, and to promote atomization of return oil supplied to the crank chamber side by action of the reed valve and hence to improve the combustibility of oil and more effectively prevent the occurrence of white smoke.
According to an invention , the specific warming state is set at a state in which catalyst in a catalyst device provided in an exhaust system of the two-cycle engine E is activated. With this configuration, it is possible to prevent oil from adhering on the catalyst, and hence to promote the activation of the catalyst and more effectively prevent the occurrence of white smoke.
To achieve the above second object, there is provided an oil recovery system for a two-cycle engine of a motorcycle, in which an oil recovery chamber disposed under a crank chamber of a two-cycle engine mounted on a motorcycle and communicated to a bottom of the crank chamber is formed in an oil recovery tank supported by the engine and the oil recovery chamber is connected to an intake system of the engine, characterized in that the oil recovery tank is provided with a partition wall for partitioning the inside of the oil recovery chamber into an upper chamber communicated to the bottom of the crank chamber and a

lower chamber connected to the intake system; the partition wall is formed into a funnel shape which allows the flow area of oil to be reduced toward the lower side; and a communication hole for communicating the upper chamber to the lower chamber is provided at the lowermost end of the partition wall. [0013]
With this configuration, oil led from the crank chamber into the oil recovery chamber flows from the upper chamber to the lower chamber through the communication hole. In this case, since the partition wall is formed into the funnel shape, the diameter of the communication -hole can be set at a "relatively small" value. As a result, it is possible to enhance the efficiency of recovery of oil from the crank chamber, by setting the flow areas of the connecting pipe and the oil lead pipe, which connect the crank chamber to the oil recovery chamber, at relatively large values while suppressing the pressure loss in the crank chamber accompanied by the return of oil to the intake system side by depression at an engine manifold thereby preventing the reduction in engine performance. Further, since the amount of oil, which counter-flows from the oil recovery chamber to the crank chamber side due to pressure pulsation of the crank

chamber, vibration from a running road surface, and vibration of the engine, can be minimized by the partition wall and the communication hole, it is possible to further enhance the efficiency of oil recovery.
According to the invention, one end of an oil lead pipe is connected to the bottom of the crank chamber at a position which becomes the lowermost end in the tilting state of the body of the motorcycle when a side stand is kept in the working state and the other end of the oil lead pipe is connected to the upper chamber. With this configuration, it is possible to effectively recover oil from the crank chamber by making use of the tilting of the body of the motorcycle in the state in which the body is tilted when the side stand is kept in the working state.
[Mode for Carrying out the Invention]
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[Brief Description of the Drawings] [Fig. 1]
A side view of a motorcycle. [Fig. 2]
A side view of a two-cycle engine, with parts partially broken away. [Fig. 3]
An enlarged sectional view taken on line 3-3 of Fig
2, in which a side stand is kept in a working state.
[Fig. 4]
A vertical side view of an exhaust system, with parts partially broken away. [Fig. 5]
An enlarged sectional view taken on line 5-5 of Fig
3. [Fig. 6]
A side view of an oil recovery tank, with parts partially broken away. [Fig. 7]
A front view seen along the direction shown by an arrow 7 of Fig. 6, with parts partially broken away.
[0016]
Figs. 1 to 7 shows one embodiment of the present

invention, wherein Fig. 1 is a side view of a motorcycle; Fig. 2 is a side view of a two-cycle engine with parts partially cutaway; Fig. 3 is an enlarged sectional view taken on line 3-3 of Fig. 2, in which a side stand is kept in a working state; Fig. 4 is a vertical side view of an exhaust system, with parts partially cutaway; Fig. 5 is an enlarged sectional view taken on line 5-5 of Fig. 3; Fig. 6 is a side view, with parts partially cutaway, of an oil recovery tank; and fig. 7 is a front view seen along the direction shown by an arrow 7 of Fig. 6, with parts partially broken away. [,0 017]
Referring first to Fig. 1, a head pipe 13 for" steerably supporting a front fork 12 is provided on a front end of a main frame 11 of a body frame F of the motorcycle according to the embodiment of the present invention. A front wheel WF is rotatably supported by lower ends of the front fork 12, and a steering handlebar
14 is connected to an upper end of the front fork 12.
[0018]
Front ends of a pair of right and left seat rails
15 extending rearwardly, upwardly are connected to an
intermediate portion of the main frame 11. Front ends of
a pair of right and left stays 16 extending rearwardly,

upwardly while being located under the seat rails 15 are connected to a rear end portion of the main frame 11. A fuel tank 17 is supported on a front portion of the main frame 11 and front portions of both the seat rails 15, and a seat 18 is provided on both the seat rails 15. [0019]
A two-cycle engine E is mounted on the main frame 11 at a position under the fuel tank 17. A front end of a rear fork 19 extending rearwardly is swingably supported by a rear portion of the main frame 11. A rear wheel WR to be rotated by an output from the engine E is rotatably supported by rear ends of the rear fork 19. A cushion unit 20--is provided between the stay's~16 and'the rear-fork 19. [0020] .
A side stand 21, which is turnable between a working position and a storage position, is provided at a lower end of a rear portion of the main frame 11. As shown in Fig. 1, when the side stand 21 at the working position is grounded on a road surface, a body of the motorcycle is tilted leftwardly while being directed forwardly in the running direction. [0021]
Referring to Figs. 2 and 3, the two-cycle engine E

includes a cylinder block 22, a cylinder head 23 connected to the cylinder block 22, and a crank case 24 connected to the cylinder block 22. A piston 26 slidably fitted in a cylinder bore 25 provided in the cylinder block 22 is connected, via a connecting rod 29 and a crank pin 30, to a crank shaft 28 rotatably supported by the crank case 24. [0022]
A combustion chamber 31, to which the top of the piston 26 faces, is formed between the cylinder block 22 and the cylinder head 23. An ignition plug 32 is mounted in the cylinder head 23 in such a manner as to face to a central-portion of the combustion chamber 311 Scavenging ports 34, which can Communicate a crank chamber 33 formed in the crank case 24 to the combustion chamber 31 by downward movement of the piston 26, are provided in the cylinder block 22 and the crank case 24. An exhaust port 35, which can be communicated to the combustion chamber 31 by downward movement of the piston 26, is provided in the cylinder block 22. An intake port 36 is provided in the crank case 24 in such a manner as to be opened to the crank chamber 33. [0023]
A reed valve 37 is mounted in the crank case 24 in

such a manner as to be disposed in the intake port 36. An
intake system 38, which is communicated to the inside of
the crank chamber 33 when the reed valve 37 is opened, is
connected to the intake port 36. The intake system 38
includes an air cleaner 40 in which a cleaner element 39
is housed, a carburetor 42 having a throttle valve 41 and
connected to the air cleaner 40, and an intake pipe 43
for connecting the carburetor 42 to the intake port 36. A
downstream end of the intake pipe 43 is fastened,
together with the reed valve 37, to the crank case 24 by
means of a plurality of bolts 44. A lower end of a branch
pipe 45 extending upwardly is connected to an
intermed-i-ate portion of the intake pipe 43, and a cn'amber
46 for reducing intaRe noise is connected to an upper end
of the branch pipe 45. .,
[0024]
An exhaust system 47 connected to the exhaust port 35 includes an exhaust pipe 48 extending from the exhaust port 35, passing under the two-cycle engine E, and further extending up to the right side of the rear wheel WR; and an exhaust muffler 49 connected to a downstream end of the exhaust pipe 48. [0025]
Referring to Fig. 4, a catalyst device 50 is housed

at a halfway point in the exhaust pipe 48. The catalyst device 50 is configured such that catalyst is supported on the surface of a punching pipe 51 fixed on the inner surface of the exhaust pipe 48 via a plurality of mounting members 52.
[0026]
Referring particularly to Fig. 5, one end of the crank shaft 28 projects in a transmission chamber 53 partitioned from the crank chamber 33. The transmission chamber 53 is formed by the crank case 24 and a transmission case 54 connected to the crank case 24. Oil is accumulated in the transmission chamber 53 up to a liquid level L- shown in Fig. 5.
[0027]
The transmission chamber 53 houses a multi-stage transmission 57 composed of a plurality of stages of gear trains allowed to be alternatively meshed. The transmission 57 is positioned between a main shaft 55 and a counter shaft 56. The main shaft 55 has an axial line parallel to that of the crank shaft 28 and is rotatably supported by the transmission case 54, and the counter shaft 56 has an axial line parallel to that of the main shaft 55 and is rotatably supported by the transmission case 54. A power is transmitted from one end, projecting

from the transmission case 54, of the counter shaft 56 to the rear wheel WR via a drive chain 58 (see Fig. 1). A drive gear 59 is fixed to one end of the crank shaft 28, and a power is inputted from the drive gear 59 to the main shaft 55. [0028]
The other end of the crank shaft 28 projects in an auxiliary chamber 60 partitioned from the crank chamber 33 and the transmission chamber 53, and a generator is connected to the other end of the crank shaft 2 8 in the auxiliary chamber 60. [0029]
At- the boundary between the crank chamber 33 'and the transmission chamber 53, a first oil seal 61 and a first ball bearing 62 offset to the transmission chamber 53 side from the first oil seal 61 are provided between the crank shaft 28 and the crank case 24. At the boundary between the crank chamber 33 and the auxiliary chamber 60, a second oil seal 63, a third oil seal 64 offset to the auxiliary chamber 60 side from the second oil seal 63, and a second ball bearing 65 positioned between the second and third oil seals 63 and 64 are provided between the crank shaft 28 and the crank case 24. [0030]

An oil-tight space 66 is formed between the second and third oil seals 63 and 64 in the crank case 24. In the oil-tight space 66, a drive screw gear 67 is provided on the crank shaft 28, and a driven screw gear 68 having an axial line perpendicular to an axial line of the crank shaft 28 is meshed with the drive screw gear 67. The driven screw gear 68 is connected to an oil pump (not shown), and the oil pump is driven by the crank shaft 28. [0031]
A mission gear 69, which constitutes part of the transmission 57, is rotated in the direction shown by an arrow in Fig. 5, with its outer periphery being in proximity to a- plane, facing to the'" transmission chamber 53, of the crank case" 24. Oil in the transmission chamber 53 is splashed up by the mission gear ^69. Meanwhile, the-crank case 24 has an oil receiving portion 70 integrally projecting from a portion over the mission gear 69 into the transmission chamber 53. The oil receiving portion 70 is allowed to receive part of oil splashed up by the mission gear 69. [0032]
The crank case 24 has an oil supply hole 71 with its one end opened to the transmission chamber 53 and the other end opened to the oil-tight space 66, and an oil

discharge hole 72 with its one end opened to the oil-tight space 66 and the other end opened to an inner bottom of the transmission chamber 53. A lower edge of the one end, opened to the transmission chamber 53, of the oil supply hole 71 is formed in such a manner as to be continuous to the upper surface of the oil receiving portion 70. [0033]
By the way, the oil supply hole 71 is formed in the crank case 24 in such a manner as to have an axial line parallel to the bolts 44 screwed in the crank case 24 for fastening the reed valve 37 to the crank case 24, and an opening-provided in the crank case 24""at a position" separated from the one end of the oil supply hole 71 is blocked, with a blocking member 73. An^ opening provided i-n the crank case 24 at a position separated from the other end, opened to the bottom of the transmission chamber 53, of the oil discharge hole 72 is also blocked with a blocking member 74. [0034]
The other end of the oil supply hole 71 is opened to the oil-tight space 66 at a position between the second oil seal 63 and the second ball bearing 65, and the one end of the oil discharge hole 72 is opened to the

oil-tight space 66 at a position between the third oil seal 64 and the second ball bearing 65. That is to say, the other end of the oil supply hole 71 and the one end of the oil discharge hole 72 are opened in the oil-tight space 66 at the positions between which the second ball bearing 65 is put.
[0035]
Oil supplied together with air-fuel mixture, and oil supplied to a lubrication portion of the engine E are accumulated on the inner bottom of the crank chamber 33, and the oil thus accumulated is recovered from the crank chamber 33 and returned to the intake system 38. To recover -such oil, an oil recovery tank '7 6 including'an oil recover chamber 75 communicated to the bottom of the crank chamber 33 is disposed under the two-cycle engine E
[0036]
Referring particularly to Fig. 6, the oil recovery tank 76 includes a tank main body 77, and a cover plate 78 fastened to a side surface of the tank main body 77 by means of a plurality of, for example, four bolts 79. The tank main body 77 is integrally provided with two supporting arms 80 and 81 extending upwardly, and upper ends of the supporting arms 80 and 81 are fastened to the crank case 24 of the two-cycle engine E. In this way, the

oil recovery tank 76 is supported by the two-cycle engine E in such a manner as to be disposed under the engine E. [0037]
The oil recovery chamber 75 is formed by closing an opening end of a circular recess provided in the tank main body 77 with the cover plate 78. An annular seal member 82 surrounding the recess is interposed between the tank main body 77 and the cover plate 78. [0038]
The oil recovery chamber 75 is partitioned into an upper chamber 75a and a lower chamber 75b by means of a partition wall 83 provided on the tank main body 77. The partition wall- 83 is formed into a funnel shape which allows the flow area "of oil to be reduced toward the lower side. A communication hole 84 for communicating the-upper chamber 75a to the lower chamber 75b is provided at the lowermost end of the partition wall 83. To be more specific, when the motorcycle is parked with the side stand 21 kept in the working state, the body of the motorcycle is, as shown in Fig. 3, tilted sideways from the vertical direction by an angle a , and the communication hole 84 is provided in the partition wall 83 r typicallyr at an end on the cover plate 18 side in such a manner that the communication hole 84 is located

at the lowermost end of the partition wall 83 in the above tilting state of the body of the motorcycle.
[0039]
A connection pipe 85 communicated to the inner bottom of the crank chamber 33 is mounted to the crank case 24 at a position which becomes the lowermost end in the tilting state of the body of the motorcycle when the side stand 21 is kept in the working state. One end of an oil lead pipe 86 is connected to the connection pipe 85, and the other end of the oil lead pipe 86 is connected to the upper chamber 7 5a. .
[0040]
Referring particularly to Fig 7, a cover 88 is fastened to the tank main body 77 of the oil recovery tank 76. with a partition plate 87 put ./between the cover -88 and the tank main body 77 by means of a plurality of, for example, four bolts 89. An inlet chamber 91, which is communicated to the lower chamber 75b of the oil recovery chamber 75 via a passage 90 provided in the tank main body 77, is formed between the tank main body 77 and the partition plate 87, and an outlet chamber 92 is formed between the partition plate 87 and the cover 88. A seal member 93 surrounding the inlet chamber 91 is interposed between the tank main body 77 and the partition plate 87,

and a seal member 94 surrounding the outlet chamber 92 is interposed between the partition plate 87 and the cover 88. [0041]
A check valve 95 is disposed in an upper portion of the partition plate 87. The check valve 95 includes a holding cylinder 97 pressed in a mounting hole 96 and a disk-shaped valve body 98 housed in the holding cylinder 97. The mounting hole 96 is formed in the upper portion of the partition plate 87 in such a manner as to communicate the inlet chamber 91 to the outlet chamber 92 [0042]
The holding cylinder 97 with its bottom close'd is pressed in the mounting hole 96 with its closed bottom disposed on the inlet chamber 91 side, A valve hole 99 i
inwardly therefrom. [0043]
The check valve 95 allows the flow of oil from the inlet chamber 91 side to the outlet chamber 92 side, but prohibits the flow of oil from the outlet chamber 92 side to the inlet chamber 91 side. [0044]
Referring particularly to Fig. 2, a connection pipe
101 is mounted to a portion, corresponding to the check valve 95, of the cover 88. One end of a return pipe line
102 is connected to the connection pipe 101, and the other end of the return pipe line 102 is connected to the intake system -38. A control valve 103 is provided at a halfway point of the return pipe line 102.
[0045] .
The control valve 103 is an electromagnetic switching valve having first, second and third ports 104, 105 and 106. The control valve 103 can switch a communication state of the first, second and third ports 104, 105 and 106 from or to a state in which the first port 104 is communicated to the second port 105 and is cutoff from the third port 106 to or from a state in which the first port 1Q4 is communicated to the third port 106 and is cutoff from the second port 105.

[0046]
The return pipe line 102 includes a first pipe line portion 102a and a second pipe line portion 102b. One end of the first pipe line portion 102a is connected to the connection pipe 101, and the other end of the first pipe line portion 102a is connected to the first port 104 of the control valve 103. One end of the second pipe line portion 102b is connected to the second port 105 of the control valve 103, and the other end of the second pipe line portion 102b is connected to a portion, located between the throttle valve 41 and the reed valve 37 of the intake system 38, that is, the intake pipe 43. [0047]
One end of an 'open pipe line 107 raised upwardly from the control valve 103 is connected to the third port 106 of the control valve 103. The other end of the open pipe line 107 is opened to atmospheric air on the upstream side from the cleaner element 39 in the air cleaner 40. [0048]
The control valve 103 is controlled by control means (not shown) as follows: namely, in a period until the engine state reaches a specific warming state after start-up of the two-cycle engine E and in the stoppage

state of the two-cycle engine E, the control valve 103 switches the communication state of the ports 104, 105 and 106 into the state in which the first port 104 is communicated to the third port 106 and is cutoff from the second port 105 in order to prohibit the return of oil from the oil recovery chamber 75 to the intake system 38; and after the engine state reaches the specific warming state, the control valve 103 switches the communication state of the ports 104, 105 and 106 into the state in which the first port 104 is communicated to the second port 105 and is cutoff from the third port 106.
[0049]
That is to say, in the period until the engine state reaches the specific warming state after start-up of the two-cycle engine E and in the stoppage state of the two-cycle engine E, the return pipe line 102 is cutoff so that the oil recovery chamber 75 is connected to the inside of the air cleaner 40 via the check valve 95.
[0050]
The above-described specific warming state is set as a state in which catalyst in the catalyst device 50 provided in the exhaust system 47 of the two-cycle engine E is activated. The activation of catalyst is decided by

detecting the temperature in the inside of the catalyst device 50, or decided on the basis of a condition that a state in which the number of revolution of the two-cycle engine E is a setting number of revolution (for example, 3000 rpm) or more is continued for a setting time (for example, one minute) or more. [0051]
The function of this embodiment will be described below. At the boundary between the crank chamber 33 and the auxiliary chamber -60, the second and third oil seals 63 and 64 are provided between the crank case 24 and the crank shaft 28 so that the oil-tight space 66 is formed between- the oil seals 63 and 64 in the crank case 24', and the second ball bearing 65 provided between the crank case 24. and the crank shaft 28 is hous-ed in the oil--tight space 66. To lubricate the second ball bearing 65, the oil receiving portion 70 capable of receiving oil in the transmission chamber 53 splashed up by the mission gear 69 is integrally provided on a portion, positioned over the mission gear 70, of the crank case 24. The oil supply hole 71 with its one end opened to the transmission chamber 53 and the other end opened to the oil-tight space 66 is provided in the crank case 24 in such a manner that the lower edge of the one end, opened to the

transmission chamber 53, of the oil supply hole 71 is continuous to the upper surface of the oil receiving portion 70. The oil discharge hole 72 with its one end opened to the oil-tight space 66 and the other end opened on the lower bottom of the transmission chamber 53 is also provided in the crank case 24. [0052]
Accordingly, oil splashed by the mission gear 69 in the transmission chamber 53 is supplied from the oil receiving portion 70 into the oil-tight space 66 via the oil supply hole 71 to lubricate the second ball bearing 65, and the oil is returned from the oil-tight space 66 into the—transmission chamber 53 via ttie oil discharge hole 72. Such a structure for lubricating the second ball bearing 65 can be obtained only by forming the oil -supply hole 71 and the oil discharge hole 72 in the crank case 24. The simple lubricating structure is advantageous in reducing the number of the machining steps as compared with the conventional lubricating structure in which an oil passage is formed in the crank shaft 28. [0053]
Since the other end of the oil supply hole 71 and the one end of the oil discharge hole 7 2 are opened in the oil-tight space 66 at the positions between which the

second ball bearing 65 is put, oil flows in the oil-tight space 66 while necessarily passing through the second ball bearing 65. As a result,.the second ball bearing 65 is certainly lubricated with oil flowing in the oil-tight space 66.
[0054]
Since the oil supply hole 71 is provided in the
crank case 24 in such a manner as to have the axial line
parallel to the bolts 44 screwed in the crank case 24 for
fastening the reed valve 37 to the crank case 24, the oil
supply hole 71 and the threaded holes in which the bolts
44 are to be screwed can be formed in the crank case 24
in the same direction. As a result, is possible to
form the oil supply hole 71 with good machinability and
productivity. J -
[0055]
To recover oil accumulated on the lower bottom of the crank chamber 3 3 from the crank chamber 3 3 and to return the oil to the intake system 38, the oil recovery tank 76 including the oil recovery chamber 75 communicated to the bottom of the crank chamber 33 is disposed under the two-cycle engine E. The oil recovery tank 76 has the partition wall 83 for partitioning the inside of the oil recovery chamber 75 into the upper

chamber 75a communicated to the bottom of the crank chamber 33 and the lower chamber 75b connected to the intake system 38. The partition wall 83 is formed into the funnel shape which allows the flow area of oil to be reduced toward the lower side. The communication hole 84 for communicating the upper chamber 75a to the lower chamber 75b is provided at the lowermost end of the partition wall 83. [0056]
Accordingly, oil led from the crank chamber 33 into the oil recovery chamber 75 flows from the upper chamber 75a to the lower chamber 75b through the communication hole 84-. —Further, since the partition wall 83 is formed into the funnel shape, the diameter of the communication hole 84. can be set at a relatively small value. As-a result, it is possible to enhance the efficiency of recovery of oil from the crank chamber 33 by setting the flow areas of the connecting pipe 85 and the oil lead pipe 86, which connect the crank chamber 33 to the oil recovery chamber 75, at relatively large values while suppressing the pressure loss in the crank chamber 33 accompanied by the return of oil to the intake system 38 side by depression at an engine manifold thereby preventing the reduction in engine performance. Further,

since the amount of oil, which counter-flows from the oil recovery chamber 75 to the crank chamber 33 side due to pressure pulsation of the crank chamber 33, vibration from a running road surface, and vibration of the engine E, can be minimized by the partition wall 83 and the communication hole 84, it is possible to further enhance the efficiency of oil recovery.
[0057]
Since the one end of the oil lead pipe 86 is connected to the lower bottom of the crank chamber 33 at a position which becomes the lowermost end in the tilting state of the body of the motorcycle when the side stand 21 is kept in -the working state and" the other end of' the oil lead pipe 86 is connected to the upper chamber 75a, it is possible to effectively recover .oil from the-crank - • chamber 33 by making use of the tilting of the body of the motorcycle in the state in which the body is tilted when the side stand 21 is kept in the working state.
[0058]
The control valve 103 for prohibiting the return of oil from the oil recovery chamber 75 to the intake system 38 until the engine state reaches the specific warming state after start-up of the two-cycle engine E is provided at a halfway point of the return pipe line 102

for returning the oil recovered to the oil recovery chamber 75 to the intake system 38. Accordingly, even by performing a snapping operation before the engine state reaches the warming state, the oil is not returned to the intake system 38, with a result that it is possible to certainly prevent the occurrence of while smoke. [0059]
The control valve 103 is the electromagnetic switching valve operated to alternatively switch, the communication state of the first port 104 connected to the oil recovery chamber 75 via the check valve 95, the second port 105 connected to the intake system 38, and the third port- 106, between the state"" in which the first port 104 is communicated to the second port 105 and the state in which the first port 104 is communicated to the third port 106. The open pipe line 107 with its one end connected to the third port 106 is raised upwardly from the control valve 103, and the other end of the open pipe line 107 is opened to atmospheric air in the air cleaner 40. [0060]
Accordingly, in the state in which the return of oil to the intake system 38 is prohibited by cutting off the communication between the first and second ports 104

and 105 and allowing the communication between the first and third ports 104 and 106, the oil recover chamber 75 does not become an enclosed state, with a result that the recovery of oil from the crank chamber 33 to the oil recovery chamber 75 can be desirably performed. Further, since the open pipe line 107 communicated to the third port 106 is raised upwardly from the control valve 103, it is possible to prevent oil from flowing on the open pipe line 107 side. [0061]
Since the oil recovery chamber 75 is connected to a portion, positioned between the throttle valve 39 and the reed valve 37,- of the intake system'" 3B via the return pipe line 102, it is'possible to prevent oil returned to the intake system 3 8 from adhering on the throttle -valve 39 and hence to improve the workability of the throttle valve 39, and to promote atomization of return oil supplied to the crank chamber 33 side by action of the reed valve 37 and hence to improve the combustibility of oil and more effectively prevent the occurrence of white smoke. [0062]
Since the specific warming state is set as the state in which catalyst in the catalyst device 50

provided in the exhaust system 47 of the two-cycle engine E is activated, it is possible to prevent oil from adhering on the catalyst, and hence to promote the activation of the catalyst and more effectively prevent the occurrence of white smoke. [0063]
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 present invention described in claims. [0064]
For example, although the control valve 103 is provided at a halfway point of the return pipe line 102 in the embodiment, it may. be mounted an the oil recovery tank 76. [0065]
[Effect of the Invention]
According to the invention since the return of oil from the oil recovery chamber to the intake system is prohibited by the control valve until the engine state reaches the specific warming state directly after start-up of the two-cycle engine, oil is not returned to the intake system even by a snapping

operation before the engine state reaches the warming state, with a result that it is possible to certainly prevent the occurrence of white smoke. [0066]
According to the invention since the oil recover chamber does not become an enclosed state in the state in which the return of oil to the intake system is prohibit, the recovery of oil from the crank chamber to the oil recovery chamber can be desirably performed. Further, it is possible to prevent oil from flowing on the open pipe line side.
[0067]
According to the invention described
is possible to prevent oil returned to the intake system
from adhering on the throttle valve and hence to improve
the workability of the throttle valve, and to promote
atomization of return oil supplied to the crank chamber
side by action of the reed valve and hence to improve the
combustibility of oil and more effectively prevent the
occurrence of white smoke.
[0068]
According to the invention described it
is possible to prevent oil from adhering on the catalyst,
and hence to promote the activation of the catalyst and

more effectively prevent the occurrence of white smoke.
[0069]
According to the invention described it
is possible to enhance the efficiency of recovery of oil
from the crank chamber by setting the flow areas of the
connecting pipe and the oil lead pipe, which connect the
crank chamber to the oil recovery chamber, at relatively
large values while suppressing the pressure loss in the
crank chamber accompanied by the return of oil to the
intake system side by depression at an engine manifold
thereby preventing the reduction in engine performance.
Further, since the amount of oil, which counter - flows
from the—oil recovery chamber to the crank chamber side
due to pressure pulsation of the crank chamber, vibration
from a running road surface, and vibration of the engine,
can be minimized by the partition wall and the
communication hole, it is possible to further enhance the
efficiency of oil recovery.
[0070]

According to the invention described it is possible to effectively recover oil from the crank chamber by making use of the tilting of the body of the motorcycle in the state in which the body is tilted when the side stand is kept in the working state.

[Explanation of Characters]
21: side stand, 33: crank chamber, 37: reed valve, 38: intake system, 41: throttle valve, 47: exhaust system,
50: catalyst device, 75: oil recovery chamber, 75a: upper chamber, 75b: lower chamber, 76: oil recovery tank, 83: partition wall, 84: communication hole, 86: oil lead pipe 102: return pipe line, 103: control valve, 104: first port, 105: second port, 106: third port, 107: open pipe line, E: two-cycle engine

WE CLAIM:
1. An oil recovery system for a two-cycle engine, in which an oil
recovery chamber (75) communicated to a bottom of a crank chamber
(33) of a two-cycle engine (E) is connected to an intake system (38) of said
two-cycle engine (E) via a return pipe line (102), characterized in that
i
said oil recovery system has a control valve (103) for prohibiting return of oil from said oil recovery chamber (75) to said intake system (38) until the engine state reaches a specific warming state after start-up of said two-cycle engine (E).
2. An oil recovery system for a two-cycle engine as claimed in claim 1,
wherein said control valve (103) is an electromagnetic switching valve
operated to alternatively switch the communication state of a first port
(104) connected to said oil recovery chamber (75) , a second port (105) connected to said intake system (38), and a third port (106), between a state in which said first port (104) is communicated to said second port
(105) and a state in which said first port (104) is communicated to said third port (106) ; and
an open pipe line (107) with its one end connected to said third port
(106) is raised upwardly from said control valve (103) , and the other end
of said open pipe line (107) is opened to atmospheric air.
3. An oil recovery system for a two-cycle engine as claimed in claim
1, wherein said oil recovery chamber (75) is connected to a portion,

positioned between a throttle valve (41) and a reed valve (37) , of said intake system (38) via said return pipe line (102).
4. An oil recovery system for a two-cycle engine as claimed in claim
1, wherein said specific warming state is set at a state in which catalyst
in a catalyst device (50) provided in an exhaust system (47) of said two-
cycle engine (E) is activated.
5. An oil recovery system for a two-cycle engine of a motorcycle as
claimed in claim 1, in which an oil recovery chamber (75) disposed under
a crank chamber (33) of a two-cycle engine (E) mounted on a motorcycle
and communicated to a bottom of said crank chamber (33) is formed in
an oil recovery tank (76) supported by said engine (E) and said oil
recovery chamber (75) is connected to an intake system (38) of said
engine (E), wherein
said oil recovery tank (76) is provided with a partition wall (83) for partitioning the inside of said oil recovery chamber (75) into an upper chamber (75a) communicated to the bottom of said crank chamber (33) and a lower chamber (75b) connected to said intake system (38);
said partition wall (83) is formed into a funnel shape which allows the flow area of oil to be reduced toward the lower side; and
a communication hole (84) for communicating said upper chamber (75a) to said lower chamber (75b) is provided at the lowermost end of said partition wall (83).
6. An oil recovery system for a two-cycle engine of a motorcycle as
claimed in claim 5 wherein one end of an oil lead pipe (86) is connected

to the bottom of said crank chamber (33) at a position which, becomes the lowermost end in the tilting state of the body of said motorcycle when a side stand (21) is kept in the working state and the other end of said oil lead pipe (86) is connected to said upper chamber (75a).
7. An oil recovery system for a two-cycle engine substantially as hereinbefore described with reference to the accompanying drawings.
Dated this 6th day of November, 2000

[RITUSHKA NEGI]
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANTS

Documents:

988-mum-2000-cancelled page(20-7-2005).pdf

988-mum-2000-claim (granted)-(20-7-2005).pdf

988-mum-2000-claim(granted)-(20-7-2005).doc

988-mum-2000-correspondence(14-3-2006).pdf

988-mum-2000-correspondence(ipo)-(18-7-2005).pdf

988-mum-2000-drawing(18-5-2001).pdf

988-mum-2000-form 1(6-11-2000).pdf

988-mum-2000-form 13(20-7-2005).pdf

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

988-mum-2000-form 2(granted)-(20-7-2005).doc

988-mum-2000-form 2(granted)-(20-7-2005).pdf

988-mum-2000-form 3(12-3-2001).pdf

988-mum-2000-form 3(6-11-2000).pdf

988-mum-2000-form 5(6-11-2000).pdf

988-mum-2000-petition under rule138(20-27-2005).pdf

988-mum-2000-power of aouthority(16-4-2003).pdf

988-mum-2000-power of aouthority(8-3-2001).pdf

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Patent Number

204335

Indian Patent Application Number

988/MUM/2000

PG Journal Number

43/2008

Publication Date

24-Oct-2008

Grant Date

15-Feb-2007

Date of Filing

06-Nov-2000

Name of Patentee

HONDA GIKEN KOGYO KABUSHIKI KAISHA

Applicant Address

1-1, MINAMIAOYAMA 2-CHOME, MINATO-KU, TOKYO, JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	JUNJI ANDO	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
2	HIROSHI YOKOTA	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
3	KAZUO FUJIHARA	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
4	AKIRA SANEMATSU	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
5	JUNICHI ISHIHARA	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.

PCT International Classification Number

N/A

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	HEI-11-329659	1999-11-19	Japan
2	HEI-11-329658	1999-11-19	Japan