JP4252590B2 - Valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a valve operating apparatus for an internal combustion engine in which at least one of the intake and exhaust valves is composed of two or more poppet valves.

In a conventional valve operating system for a 4-stroke cycle internal combustion engine, one of the intake and exhaust valves is driven to open and close from the camshaft via a rocker arm, and the other valve is driven to open and close directly from the camshaft. There is something.
Japanese Patent Laid-Open No. 5-133207

In the valve operating apparatus, three intake poppet valves and two exhaust poppet valves are arranged for each cylinder, and each of these poppet valves has five cam peaks per cylinder corresponding to one-to-one. A camshaft is prepared, and the top ends of one of the three intake poppet valves are brought into contact with the three cam peaks of the camshaft, respectively, and are directly driven to open and close by the cam peaks. Since the exhaust poppet valve is driven to open and close by two cam ridges of the camshaft via two rocker arms, a large number of cam ridges are required, and the rocker arm 2 bypasses the spark plug. This was necessary, the number of parts increased, the structure became complicated, and there were disadvantages in terms of productivity and cost.

Means and effects for solving the problems

The present invention relates to an improvement in a valve operating apparatus for an internal combustion engine that has overcome such difficulties, and the cylinder head is provided with two intake poppet valves and two exhaust poppet valves, and the above-mentioned cylinder head is provided with the above- mentioned In an internal combustion engine in which a camshaft for opening and closing an intake / exhaust valve is disposed , the camshaft includes a single central cam peak and a pair of cam peaks formed on both sides of the central cam peak. And a pair of rolling bearings disposed adjacent to the opposite side of the pair of cam ridges from the central cam ridge, and rotatably supported between the cam shaft and the exhaust poppet valve. , rocker arm shaft for supporting the single rocker arm swingably is disposed, the rocker arm, the action of the central cam lobes supported by the shaft of bracket tip projecting toward the camshaft A roller for receiving the and a branch section for driving the respective exhaust poppet valve from the camshaft side branches towards each of the two exhaust poppet valve, said rocker arm shaft, the axis of the roller The two intake poppet valves are disposed below and below the camshaft, and the two intake poppet valves are driven to open and close through the lifters by the pair of cam ridges, and have a cylindrical portion that slidably supports the lifters. A bottom is provided below the camshaft, the bottom connects the pair of rolling bearings, a wall is formed behind the camshaft, and the wall and the bottom serve as a lubricating oil reservoir. It characterized that you form a corner.

Since the invention described in claim 1 is configured as described above, it is only necessary to provide one cam crest for two or more poppet valves on the side opened and closed by the rocker arm. The book is sufficient, the number of parts and the number of assembly steps are reduced, the weight can be reduced, the structure can be simplified, and the productivity and cost can be greatly reduced.

According to a second aspect of the present invention, in the valve operating apparatus for an internal combustion engine according to the first aspect, a part of the exhaust poppet valve is disposed above a mating surface between the cylinder head and the cylinder head cover, and the cam A drive sprocket is fitted to one end of the shaft closer to the end of the camshaft than the rolling bearing, and a cam chain is stretched across the drive sprocket. The cylinder head cover includes the drive sprocket and the A space for accommodating the Kamchien is formed.

According to a third aspect of the present invention, in the valve operating apparatus for an internal combustion engine according to the first or second aspect, a support portion for supporting the rocker arm shaft is provided on a camshaft holder for holding the camshaft, and the support portion. A support boss extending in the vertical direction is provided at the top.

The embodiment of the present invention illustrated in FIGS. 1 to 4 will be described above.
The water-cooled head valve spark ignition type single-cylinder four-stroke throttle internal combustion engine 1 is mounted on a motorcycle (not shown) so that the crankshaft 6 is directed in the vehicle width direction, and as shown in FIG. The cylinder block 3, the cylinder head 4 and the cylinder head cover 5 are sequentially stacked on top of each other, and the crankcase 2, the cylinder block 3, the cylinder head 4 and the cylinder head cover 5 are integrally coupled to each other with bolts (not shown) passing through them. Has been.

  The crankshaft 6 is pivotally supported by the crankcase 2, and a piston 8 is fitted in the cylinder hole 7 of the cylinder block 3 so as to be slidable up and down. The piston pin 9 of the piston 8 and the crankshaft 6 Both ends of the connecting rod 11 are pivotally attached to the crank pin 10, and are defined by a substantially stepped triangular concave surface at the center of the lower surface of the cylinder head 4, the cylinder hole 7, and the top surface of the piston 8. In the combustion chamber 12, the piston 8 is pressed downward by the combustion gas ignited by a spark plug 13 (see FIG. 3) near the top dead center of the piston 8, and the crankshaft 6 is pressed by the pressing force. Is driven to rotate.

Further, a pair of left and right intake ports 14 are formed on the rear side of the cylinder head 4 (right side in FIG. 1), and a pair of left and right exhaust ports on the front side of the cylinder head 4 (left side in FIG. 1). 15 is formed, and an intake poppet valve 16 and an exhaust poppet valve 17 that open and close the openings of the intake port 14 and the exhaust port 15, respectively, are slidably fitted to the guide cylinder 18 at a small angle of the valve narrow angle, A valve spring 20 is interposed between a lifter 37 (intake poppet valve 16 side) and a retainer 19 (exhaust poppet valve 17 side) provided at the top ends of the intake poppet valve 16 and exhaust poppet valve 17 and the top surface of the cylinder head 4. The intake poppet valve 16 and the exhaust poppet valve 17 are always closed by the spring force of the valve spring 20.

  Furthermore, as shown in FIG. 2, a die-shaft camshaft holder 25 for pivotally supporting the camshaft 21 via a rolling bearing 39 so that the camshaft 21 is parallel to the crankshaft 6. However, the camshaft holder 25 is integrally attached to the cylinder head 4 with a bolt (not shown), and the planar shape of the camshaft holder 25 is formed in a substantially U shape, and is located at the left end of the camshaft 21 (front side in FIGS. 3 and 4). A drive sprocket 26 is integrally fitted, and a drive sprocket 27 fitted to the left side of the crankshaft 6 and an endless cam chain 28 are bridged between the drive sprocket 26 and the teeth of the drive sprocket 27 and the drive sprocket 26. The number is set to 2: 1, and when the crankshaft 6 rotates, the camshaft 21 is driven to rotate at a rotational speed of 1/2. Going on.

  Thus, one of the mounting holes of the camshaft holder 25 with respect to the cylinder head 4 is used as an oil passage, and the oil passage of the camshaft holder 25 is directed toward the cam peaks 22, 23, 24 of the camshaft 21. Lubricating oil is discharged.

Further, as shown in FIG. 1, the rocker arm shaft 29 is fitted to the camshaft holder 25 so as to be positioned below the front side (left side) of the vehicle body with respect to the camshaft 21, and the rocker armshaft 29 is connected to the camshaft holder 25. The rocker arm 30 is pivotally supported by the rocker arm shaft 29 so that the rocker arm 30 is swingably supported. A roller 33 is pivotally supported by a pair of left and right brackets 31 at one end of the arm 30 (the rear end side of the vehicle body) via a shaft 32, and the other end of the rocker arm 30 branches in a U-shape to the left and right. The both ends of the branching portion are brought into contact with the top ends of the two exhaust poppet valves 17 located at the front of the vehicle body (left end in FIG. 1), and the roller 33 at one end of the rocker arm 30 It is contact with the vehicle body forward position in the center of the cam nose 22 of the cam shaft 21. As shown in FIG. 4, the rocker arm shaft 29 is supported by a support portion 40 that forms a part of the camshaft holder 25, and the support portion 40 is provided with a vertical boss 41.

  As shown in FIG. 1, a bottom portion 35 is formed from the lower end of the wall portion 34 at the rear of the vehicle body of the camshaft holder 25 toward the front obliquely upward, and a lifter 37 of the intake poppet valve 16 is formed on the bottom portion 35. A cylindrical portion 36 that can be loosely fitted is formed.

  Further, the tops of the two intake poppet valves 16 located on the rear side of the vehicle body (on the right side in FIG. 1) are connected to cam peaks 23 positioned on both the left and right sides of the central cam mountain 22 via the lifter 37. The cam peaks 22, 23, 24 of the camshaft 21 have intake characteristics and exhaust characteristics suitable for the required operating conditions of the water-cooled overhead valve spark ignition type single-cylinder four-cycle throttle internal combustion engine 1. Each of the intake poppet valve 16 and the exhaust poppet valve 17 is formed in a predetermined shape.

  Furthermore, as shown in FIG. 1, the ignition plug guide cylinder 38 is formed integrally with the cylinder head 4 in a state of being slightly forwardly tilted and positioned approximately at the center between the intake poppet valve 16 and the exhaust poppet valve 17 in a side view. The spark plug 13 is detachably fitted to the lower end of the spark plug guide cylinder 38. The spark plug guide cylinder 38 may be press-fitted integrally with the cylinder head 4 or may be cast integrally with the cylinder head 4.

  In the embodiment shown in FIGS. 1 to 4, as described above, the intake poppet valve 16 having a large valve diameter and a large valve weight is directly opened and closed by the cam peaks 23 and 24 of the camshaft 21 to reduce the valve weight. Since the exhaust poppet valve 17 is indirectly opened / closed by the cam crest 22 via the rocker arm 30, the equivalent weight of the intake system and the exhaust system is equalized, and the valve opening / closing follow-up characteristics in the high-speed rotation range are excellent.

  Also, since the camshaft 21 is one and the rocker arm 30 is branched into a U-shape so as to straddle the wall 34 containing the spark plug 13, the intake poppet valve 16 and the exhaust poppet valve The narrow valve angle of 17 is set small. As a result, a combustion chamber having a high compression ratio and high combustion efficiency is easily configured, and a high-performance water-cooled overhead valve spark ignition type single-cylinder four-stroke throttle engine 1 is obtained. It is done.

Furthermore, only one camshaft 21 is sufficient, the camshaft 21 and the rocker arm shaft 29 are pivotally supported by one camshaft holder 25, and the two exhaust poppet valves 17 are driven to open and close by one rocker arm 30. Therefore, the number of parts is remarkably reduced, the structure is simplified, and a great reduction in cost and weight can be achieved.

  Furthermore, as shown in FIG. 1, the camshaft holder 25 has a wall portion 34 formed at the rear portion thereof, and a bottom portion 35 slightly inclined upward toward the front at the lower edge of the wall portion 34. Therefore, the corner portions of the wall portion 34 and the bottom portion 35 serve as a lubricating oil reservoir, and the contact portion between the cam crest 22 and the lifter 37 is sufficiently lubricated.

  In addition, the position where the lifter 37 of the intake poppet valve 16 contacts the cam peaks 23 and 24 and the position where the roller 33 of the rocker arm 30 of the exhaust poppet valve 17 contacts the cam peaks 22 are the center axis of the camshaft 21. The opening timing of the intake poppet valve 16 and the exhaust poppet valve 17 is 180 ° at the rotation angle of the crankshaft 6 and 90 ° at the rotation angle of the camshaft 21. The cam peaks of the cam peak 22 and the cam peaks 23 and 24 have substantially the same phase angle.

  In addition, since the direction of the valve opening reaction force of the intake poppet valve 16 and the direction of the valve opening reaction force of the exhaust poppet valve 17 are approximately 90 degrees different from each other, a large valve opening reaction force acts on the camshaft 21. Therefore, it is not necessary to increase the rigidity of the camshaft 21, so that the weight can be reduced and the speed can be increased.

  Further, since the roller 33 is pivotally supported at one end of the rocker arm 30, the rotational frictional force of the camshaft 21 is reduced and the friction of the cam crest 22 is small.

  Furthermore, since the camshaft 21 is fitted to the camshaft holder 25 via a rolling bearing 39 having a larger diameter than the cam ridges 22, 23, 24 of the camshaft 21, the camshaft 21 is attached to the camshaft holder 25. Since it can be fitted from the side, the assemblability is greatly improved.

It is a vertical side view of the internal combustion engine provided with the valve gear of the present invention. FIG. 2 is a longitudinal front view of the internal combustion engine shown in FIG. 1. FIG. 3 is a top view of the internal combustion engine with a cylinder head cover removed. It is a principal part expansion perspective view of the said valve operating apparatus.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Water-cooled head valve spark ignition type single cylinder 4 cycle throttle internal combustion engine, 2 ... Crank case, 3 ... Cylinder block, 4 ... Cylinder head, 5 ... Cylinder head cover, 6 ... Crankshaft, 7 ... Cylinder hole, 8 ... Piston , 9 ... Piston pin, 10 ... Crank pin, 11 ... Connecting rod, 12 ... Combustion chamber, 13 ... Spark plug, 14 ... Intake port, 15 ... Exhaust port, 16 ... Intake poppet valve, 17 ... Exhaust poppet valve, 18 ... Guide cylinder, 19 ... Retainer, 20 ... Valve spring, 21 ... Camshaft, 22 ... Cam crest, 23 ... Cam crest, 24 ... Cam crest, 25 ... Camshaft holder, 26 ... Drive sprocket, 27 ... Drive sprocket, 28 ... Cam Chain, 29 ... Rocker Arm Shaft, 30 ... Rocker Arm, 31 ... Bracket, 32 ... Shaft, 33 ... Roller, 34 ... Wall, 35 ... Bottom, 36 ... Tube, 37 ... Lifter, 38 ... Spark plug guide tube, 39 ... rolling bearing.

Claims (3)

In the internal combustion engine in which the cylinder head is provided with two intake poppet valves and two exhaust poppet valves, and a camshaft that opens and closes the intake and exhaust valves is arranged on the upper part of the cylinder head .
The camshaft includes a single central cam peak and a pair of cam peaks formed on both sides of the central cam peak, and is opposite to the central cam peak of the pair of cam peaks. Are rotatably supported by a pair of rolling bearings arranged adjacent to
A rocker arm shaft that swingably supports a single rocker arm is disposed between the camshaft and the exhaust poppet valve, and the rocker arm is attached to an axis of a bracket tip that protrudes toward the camshaft. A roller that is supported and receives the action of the central cam crest, and a branch portion that branches from the camshaft side toward each of the two exhaust poppet valves to drive each of the exhaust poppet valves. ,
The rocker arm shaft is disposed below the axis of the roller and below the camshaft;
The two intake poppet valves are driven to open and close through the lifter by the pair of cam peaks ,
A bottom portion having a cylindrical portion that slidably supports the lifter is provided below the camshaft, and the bottom portion connects the pair of rolling bearings,
Wherein the rear of the cam shaft wall portion is formed, the bottom portion and the wall portion is a valve gear of an internal combustion engine, it characterized that you form a corner portion serving as a reservoir lubricant. A portion of the exhaust poppet valve is disposed above the mating surface of the cylinder head and the cylinder head cover;
At one end of the camshaft, a drive sprocket is fitted on the end side of the camshaft with respect to the rolling bearing, and a cam chain is bridged endlessly on the drive sprocket,
The valve operating apparatus for an internal combustion engine according to claim 1, wherein a space for accommodating the drive sprocket and the cam chain is formed in the cylinder head cover. 3. A camshaft holder for holding the camshaft is provided with a support portion for supporting the rocker arm shaft, and a support boss extending in the vertical direction is provided on the support portion. The valve operating apparatus for an internal combustion engine according to 1. "

Images