Title of Invention

"AN APPARATUS FOR LUBRICATING A CAM DRIVE MEMBER IN A FOUR CYCLE INTERNAL COMBUSTION ENGINE"

Abstract

[Object] To provide a system for lubricating a drive member for driving a cam shaft integrated with a valve gear cam for opening/closing intake and exhaust valves of a four-cycle internal combustion engine. [Construction] Chain chambers 22, 24 and 25 are formed in a left crank case 4, a cylinder block 6, and a cylinder head 7, respectively. A chain tensioner 31 and a chain guide 35 are respectively disposed in the upper and lower portions of the chain chambers 22, 24 and 25. A guide rib 3 9 and a tilting portion 40 are formed in a partitioning lid 3 8 removably fitted in a circular opening 37 formed in the left crank case 4, and a communicating hole 23a is provided substantially over the tilting portion 40.

Full Text

The present invention relates to an apparatus for lubricating a cam drive member in a four cycle internal combustion engine. Specifically, the present invention relates to an apparatus for lubricating a drive member for driving a cam shaft integrated with a valve gear cam for opening/closing intake and exhaust valves in a four-cycle internal combustion engine. [0002] [Prior Art] In a conventional foui'-cycle internal combustion engine, sprockets are integrally fitted on a crank shaft and a cam shaft respectively to rotate a cam shaft integrated with a valve gear cam for opening/closing intake and exhaust valves, and to prevent the elongation of an endless chain due to wear and a change in the length thereof due to thermal expansion, the endless chain is hung between these sprockets, and a chain tensioner for stretching the endless chain is provided on the loosened side of the endless chain while a chain guide is provided on the stretched side of the endless chain. [0003] [Problem to be Solved by the Invention] Even in the valve gear of such a chain drive system, the endless chain is possibly slipped off the sprockets under some operational condition of the internal combustion engine, and to prevent the slip-off of the endless chain, a chain slip-off preventive member must be provided. [0004] However, in the case where the chain slip-off preventive member is provided near the sprockets in a narrow chain chamber, upon exchange of the endless chain, the chain slip-off preventive member obstructs the exchange of the chain, and thereby the chain slip-off preventive member must be removed before the exchange of the chain. This presents a disadvantage in requiring a complex structure for removing the chain slip-off preventive member. [0005] On the other hand, the endless chain and sprockets are required to be sufficiently lubricated. However, in an internal combustion engine where a generator and a dry type belt transmission easier to be damaged by the presence of oil are disposed outwardly from the chain drive sprocket integrated with the crank shaft, it is difficult to provide the structure of removing the chain slip-off preventive member because of the presence of the generator and the dry type belt transmission. [0006] [Means for Solving the Problem and Functional Effect] To solve the above problem, according to the present invention, there is provided an improved system for lubricating a cam drive member in a four-cycle internal combustion engine, characterized in that a cam shaft drive member and a power take-out member are disposed in parallel on shafts outwardly from a bearing portion of a crank shaft rotatably supported in a crank case; a partitioning portion for liquid-tightly partitioning the cam shaft drive member in an oil-saturated atmosphere is interposed between the cam shaft drive member and the power take-out member; a guide rib is projectingly provided on the inner wall of a cam shaft drive member-containing case partitioned by the partitioning portion in such a manner as to be adjacent to the outer periphery of the cam shaft drive member; and an oil discharge port opened from the crank chamber to the guide rib in the oil-saturated atmosphere is provided on the inner wall of the case partitioning the crank chamber from the oil-saturated atmosphere. [0007] With the above construction of the present invention, a space surrounding a cam shaft drive member disposed on a crank shaft and a power take-out member is liguid-tightly partitioned by a partitioning portion, so that a generator and dry type belt motor easier to be damaged by the presence of oil can be disposed in such a manner as to be adjacent to the space surrounding the cam shaft drive member in an oil-saturated atmosphere. [0008] In the present invention, a guide rib is projectingly provided on the partitioning member in such a manner as to be adjacent to the outer periphery of the cam shaft drive member, and an oil discharge port opened from the crank chamber to the guide rib in the oil-saturated atmosphere is provided on the inner wall of the case for partitioning the crank chamber from the oil-saturated atmosphere. With this construction, oil dipped up along with the operation of the internal combustion engine within the crank chamber is discharged from the oil discharge port of the inner wall of the case to the guide rib in the oil-saturated atmosphere, thus lubricating the cam shaft drive member adjacent to the guide rib. [0009] In the present Invention, as described in claim 2, the partitioning portion comprises a partitioning iid removably mounted on a main body of the internal combustion engine, and. thereby the maintenance axt*± checking of the cam shaft drive member can be easily performed. [0010] Xn the present invention, as described in claim 3, the guide rib is positioned on the side of the cam shaft drive member; the upper portion of the guide rib is tilted in the direction being separated from the cam shaft drive member; and the oil discharge port provided on the case inner wall is disposed over the guide rib, so that oil discharged from the oil discharge port can be certainly introduced between the guide rib and the cam shaft drive member, thus sufficiently lubricating the cam shaft drive member. Accordingly, this aspect of the invention provides that the guide rib be positioned radially outwardly of said cam shaft drive member; the upper portion of said guide rib is tilted in the direction of being separated from the said cam shaft drive member; and said oil discharge port provided on said inner wall of said case is disposed over said guide rib. In the present invention, as described in claim 4, in the case where the cam shaft drive member is composed of a drive sprocket and an endless chain wound around the drive sprocket, the endless chain can be easily exchanged by removing the partitioning lid, thus effectively and easily performing the maintenance and the checking. In the present invention, as described in claim 5, by integrating the guide rib with the partitioning portion, the structure can be simplified, resulting in the reduced cost. Thus according to this aspect of the invention the guide rib is projectingly provided on said partitioning portion. Therefore, the present invention provides for an n apparatus for lubricating a cam drive member in a four-cycle internal combustion engine, characterized in that a cam shaft drive member and a power take-out member are disposed in parallel on shafts outwardly from a bearing portion of a crank shaft rotatably supported in a crank case; a partitioning portion for liquid-tightly partitioning the cam shaft drive member in an oil-saturated atmosphere is interposed between the cam shaft drive member and the power take-out member; a guide rib is projectingly provided on the inner wall of a cam shaft drive member-containing case partitioned by the partitioning portion, said guide rib being provided to be adjacent to the outer periphery of the cam shaft drive member; and an oil discharge port opened from the crank chamber to the guide rib in the oil-saturated atmosphere is provided on the inner wall of the case partitioning the crank chamber from the oil-saturated atmosphere. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS [Fig. 1] A vertical sectional side view taken along lie I-I of Fig. 1, which shows one embodiment of a system for lubricating a cam shaft drive member in a four-cycle internal combustion engine according to the present invention. [Fig. 2] A vertical sectional view taken along line II-II of Fig. 1. [0013] [Embodiment] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. A swing power unit 1 mounted on a scooter type motor-bicycle (not shown) has an air-cooled four-cycle internal combustion engine 2 in which a cylinder block 6 and a cylinder head 7 are directed slightly upwardly from the front side; and a dry type V-belt non-stage transmission 3 integrated with the engine 2 and directed rearwardly from the left side thereof. [0014] The swing power unit 1 is divided into members: a left crank case 4 serving as both a left crank case of the internal combustion engine 2 and a transmission case of the non-stage transmission 3; a right crank case 5 of the engine 2; the cylinder block 6 integrally connected to the left crank case 4 and the right crank case 5; the cylinder head 7 connected to the top end of the cylinder block 6; a transmission cover 8 removably mounted on the left side of the left crank case 4; and a right cover 9 connected to the right side of the right crank case 5. [0015] A large diameter end portion 15 of a connecting rod 14 is rotatably fitted by way of a needle bearing 13 on a crank pin 12 of a crank shaft 11 which is pivotably supported in the left crank case 4 and the right crank case 5 by way of bearings 10. A small diameter end portion 16 of the connecting rod 14 is connected to a piston 17 by way of a piston pin 18. With this construction, as the piston 17 is reciprocated within a cylinder hole 19, the crank shaft 11 is rotated. [0016] On the left side of a crank chamber 2 0 surrounded by the left crank case 4 and the right crank case 5, a chain chamber 22 is partitioned by a bulkhead 21 for supporting the left side bearing 10. The chain chamber 22 is communicated to the crank chamber 20 by way of a communicating hole 23. [0017] Chain chambers 24, 25 are respectively formed in the cylinder block 6 and the cylinder head 7 along the center line of the cylinder hole 19. In the chain chamber 22, a drive sprocket 26 is integrally fitted on the crank shaft 11; a cam shaft 28 integrally formed with a cam 27 for opening/closing intake/exhaust valves (not shown) is pivotably supported on the cylinder head 7,- and a driven sprocket 29 having the number of teeth being twice that of the drive sprocket 26 is integrally fitted at the left end of the can shaft 28. An endless chain 3 0 is hung between the drive sprocket 26 and the driven sprocket 29. With this construction, as the crank shaft 11 is rotated, the cam 27 and the cam shaft 28 are rotated at a rotational speed being half that of the crank shaft 11. [0018] A chain tensioner 31 is disposed over the chain chambers 22, 24, and 25. The base portion of the tensioner 31 is pivotably supported on a supporting piece 32 of the left crank case 4 in such a manner as to be freely rocked in the vertical direction. A tension adjusting device 3 3 is disposed on the cylinder block 6 in such a manner as to be positioned over the intermediate portion of the chain tensioner 31. The endless chain 30 is applied with a specified tension by a method of pushing down a plunger 34 of the tension adjusting device 33 by the spring force of a coil spring (not shown) in the tension adjusting device 33, and rocking down the chain tensioner 31 around the supporting piece 32. [0019] A chain guide 35 is disposed under the chain chambers 22, 24, and 25 so that the endless chain 30 is stably driven within the chain chambers 22, 24 and 25. [0020] A large diameter circular opening 37 concentric with the crank shaft 11 is formed in the left crank case 4 in such a manner as to be communicated to a transmission space 3 6 within the transmission cover 8. A bolt (not shown) passes through a partitioning lid 3 8 removably fitted in the circular opening 37, and is screwed with a female screw portion 41 of the left crank case 4. An oil seal 42 is interposed between the partitioning lid 3 8 and the crank shaft 11. [0021] Thus, on the right side surface of the partitioning lid 38, an arcuate guide rib 39 is formed behind the drive sprocket 26 and along the outer periphery of the drive sprocket 26. A tilting portion 40 tilted rearwardly and upwardly is formed on the upper portion of the guide rib 39. [0022] In Fig. 1, oil in the crank chamber 20, which is dipped up by a crank weight 45 integrated with the crank shaft 11 rotated counterclockwise, is intended to be discharged along a counterclockwise pitch circle 44 of a drive gear 43 of the kick-scooter from a communicating hole 23a which is one of four communicating holes 23. [0023] According to the above construction of the embodiment shown in the figures, when the air-cooled four-cycle internal combustion engine 2 is operated, in Fig. 1, the crank shaft 11 is rotated counterclockwise, and oil dipped up by the crank weight 45 integrated with the crank shaft 11 in the crank chamber 20 is discharged from the communicating hole 23a into the chain chamber 22 along with the counterclockwise rotation of the drive gear 43. The oil thus discharged is collected between the guide rib 3 9 and the drive sprocket 2 6 by the tilting portion 40, thus lubricating the drive sprocket 26 and the endless chain 30. [0024] The chain chamber 22 in an oil-saturated atmosphere is liquid-tightly shielded from the transmission space 36 by means of the partitioning lid 38 and an oil seal 42, so that the transmission space 3 6 is kept in an oil non-saturated atmosphere, thus enabling smooth movement of the dry type non-stage transmission 3 easier to be damaged by the presence of the oil. [0025] The partitioning lid 3 8 is removably mounted in the circular opening 37, and the guide rib 39 and the tilting portion 40 are integrally formed in the circular opening 37, so that upon exchange of the endless chain 30, only by removal of the circular opening 37, the endless chain 3 0 is extremely easily exchanged. This makes it possible to effectively perform the maintenance and checking. [0026] In the embodiment shown in the figures, a sprocket is used as the cam shaft drive member; however, a drive gear may be used in the form to be connected to a driven gear integrated with the cam shaft. [Explanation of Symbols] 1: swing power unit, 2: air-cooled four-cycle internal combustion engine, 3: V-belt type non-stage transmission, 4: left crank case, 5: right crank case, 6: cylinder block, 7: cylinder head, 8: transmission cover, 9: right cover, 10: bearing, 11: crank shaft, 12: crank pin, 13: needle bearing, 14: connecting rod, 15: large diameter end portion, 16: small diameter end portion, 17: piston, 18: piston pin, 19: cylinder hole, 20': crank chamber, 21: bulkhead, 22: chain chamber, 23: communicating hole, 24, 25: chain chamber, 26: drive sprocket, 27: cam, 28: cam shaft, 29: driven sprocket, 30: endless chain, 31: chain tensioner, 32: supporting piece, 33: tension adjusting device, 34: plunger, 35: chain guide, 36: transmission space, 37: circular opening, 38: partitioning lid, 39: guide rib, 40: tilting portion, 41: female portion, 42: oil seal, 43: drive gear, 44: pitch circle, 45: crank weight CLAIM: 1. An apparatus for lubricating a cam drive member in a four-cycle internal combustion engine, characterized in that a cam shaft drive member and a power take-out member are disposed in parallel on shafts outwardly from a bearing portion of a crank shaft rotatably supported in a crank case; a partitioning portion for liquid-tightly partitioning the cam shaft drive member in an oil-saturated atmosphere is interposed between the cam shaft drive member and the power take-out member; a guide rib is projectingly provided on the inner wall of a cam shaft drive member-containing case partitioned by the partitioning portion, said guide rib being provided to be adjacent to the outer periphery of the cam shaft drive member; and an oil discharge port opened from the crank chamber to the guide rib in the oil-saturated atmosphere is provided on the inner wall of the case partitioning the crank chamber from the oil-saturated atmosphere. 2. An apparatus as claimed in claim 1, wherein said partitioning portion comprises a partitioning lid removably mounted on a main body of said internal combustion engine. 3 An apparatus as claimed in claim 1, wherein said guide rib is positioned radially outwardly of said cam shaft drive member; the upper portion of said guide rib being tilted to separate said guide rib from the said cam shaft drive member; and said oil discharge port provided on said inner wall of said case is disposed over said guide rib. 4. An apparatus as claimed in claim 1, wherein said cam shaft drive member comprises a drive sprocket and an endless chain wound around said drive sprocket. 5. An apparatus as claimed in ckdm 1, wherein said guide rib is projectmgly provided on said partitioning portion. 6. An apparatus for lubricating a cam drive member in a four-cycle internal combustion engine substantially as herein described and with reference to and as illustrated in the accompanying drawings.

Documents:

378-del-1995-abstract.pdf

378-del-1995-claims.pdf

378-del-1995-correspondence-others.pdf

378-del-1995-correspondence-po.pdf

378-del-1995-description (complete).pdf

378-del-1995-drawings.pdf

378-del-1995-form-1.pdf

378-del-1995-form-13.pdf

378-del-1995-form-2.pdf

378-del-1995-form-4.pdf

378-del-1995-form-9.pdf

378-del-1995-gpa.pdf

378-del-1995-petition-others.pdf

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