JP2004278435A - Positioning structure of rocker arm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve positioning structure of a rocker arm in a valve system of an internal combustion engine. <P>SOLUTION: In the valve system of the internal combustion engine, the rotation of intake/exhaust cams is respectively transmitted to intake/exhaust valves through the rocker arm 28, and the intake/exhaust valves are respectively opened and closed at predetermined timings. The rocker arm 28 is swingably attached to a rocker arm shaft 26 while providing a space in the axial direction, and a collar 27 is inserted in the space. The collar 27 is C-shaped in cross section having a cutting slit along the rocker arm shaft 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a positioning structure for a rocker arm in a valve train of an internal combustion engine.
[0002]
[Prior art]
Conventionally, as a positioning structure of a rocker arm in a valve train of an internal combustion engine, a cylinder portion is provided on one side of a rocker arm that is swingably supported on a rocker arm shaft inserted through a cylinder head, and an elastic cylinder is inserted into the cylinder portion. In some cases, the elastic cylinder is elastically inserted between the rocker arm and the end face of the cylinder head (for example, see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 54-161412.
[0004]
[Problem to be solved]
In the conventional rocker arm positioning structure, since the rocker arm cannot be moved in the axial direction, when the tappet clearance of the intake / exhaust valve is adjusted by the shim type, the rocker arm shaft must be removed to replace the shim. The rocker arm had to be removed from the cylinder head. Further, since the rocker arm and the elastic cylinder swing together, the inertial mass increases, and the end face of the rocker arm is pressed against the cylinder head, so that the sliding resistance is high.
[0005]
Means and effects for solving the problem
In order to solve the above-mentioned conventional problem, the invention according to claim 1 transmits the rotation of the intake / exhaust cam to the intake / exhaust valve via a rocker arm, and controls the intake / exhaust valve at a predetermined timing. In a valve operating device for an internal combustion engine adapted to open and close, said rocker arm is mounted on a rocker arm shaft so as to be swingable and provided with a space in an axial direction, and a collar is inserted into said space. This is the positioning structure.
[0006]
According to the first aspect of the present invention, the rocker arm is swingably mounted on the rocker arm shaft and provided with a space in the axial direction, and a collar is inserted into the space, thereby increasing the inertial mass of the rocker arm. Therefore, the axial movement of the rocker arm can be prevented without increasing the sliding resistance, so that the friction of the valve train can be reduced and the fuel efficiency can be improved. In addition, by making the collar an elastic body, it is possible to suppress the tapping sound due to the axial movement of the rocker arm.
[0007]
Next, according to a second aspect of the present invention, in the first aspect of the present invention, the collar is made of a resin having a C-shaped cross section having a cutout slit along the rocker arm axis. It is.
[0008]
Therefore, in the second aspect of the invention, the collar can be easily attached to and detached from the rocker arm shaft by opening the opening (notch slit) of the C-shaped cross section of the collar. Therefore, when performing shim type tappet clearance adjustment, the collar is removed from the rocker arm axis without removing the rocker arm or rocker arm axis from the cylinder head, and the rocker arm is moved in the axial direction on the rocker arm axis. Simply by doing so, the shim can be replaced, greatly improving workability.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
1 is a longitudinal sectional view of an internal combustion engine to which an embodiment of the present invention is applied, taken along a plane substantially passing through a crank axis and a cylinder axis. FIG. 2 is also taken along a plane passing substantially through a cylinder axis and perpendicular to the crank axis. FIG. 3 is a vertical cross-sectional view similarly cut along a plane orthogonal to the crank axis near the cam chain, and FIG. 4 is an enlarged view of the upper part of FIG. 5 is a view of the cylinder head viewed from above with the cylinder head cover removed, FIG. 6 is a sectional view taken along the line VI-VI of FIGS. 5 and 7, and FIG. 7 is a view taken along the line VII-VII of FIGS. It is sectional drawing. FIGS. 8A and 8B show the collar 27 in FIGS. 5 to 7, wherein FIG. 8A is a plan view, FIG. 8B is a front view, FIG. 8C is a bottom view, and FIG. It is arrow D sectional drawing.
[0010]
This internal combustion engine 1 is an overhead valve type four-stroke cycle single cylinder internal combustion engine, and its main body is divided into left and right crankcases 2a and 2b, a cylinder block 3, and a cylinder block 3, as shown in FIGS. It comprises a cylinder head 4, a cylinder head cover 5, a left crankcase cover 6a, and a right crankcase cover 6b. The left crankcase 2a and the right crankcase 2b are fitted to each other, and the cylinder block 3, the cylinder head 4, and the cylinder head cover 5 are sequentially stacked above the left crankcase 2a and the right crankcase 2b. A left crankcase cover 6a is fitted on the left side of the left crankcase 2a, and a right crankcase cover 6b is fitted on the right side of the right crankcase 2b. The left and right crankcases 2a and 2b, the cylinder block 3, the cylinder head 4, the cylinder head cover 5, the left crankcase cover 6a, and the right crankcase cover 6b are integrally joined together by bolts or the like.
[0011]
As shown in FIGS. 1 and 2, a piston 8 is slidably fitted in a cylinder hole 7 formed in the cylinder block 3, and a crankshaft 9 is rotatable around left and right crankcases 2a and 2b. Is pivoted to. Both ends of a connecting rod 12 are rotatably connected to the piston 8 and the crankshaft 9 via a piston pin 10 and a crankpin 11, respectively. Thus, when the piston 8 reciprocates due to the combustion of the air-fuel mixture in the combustion chamber 13 at the top of the cylinder hole 7, the crankshaft 9 is driven to rotate.
[0012]
An intake port 14 and an exhaust port 15 communicating with the combustion chamber 13 at the top of the cylinder hole 7 are formed in the cylinder head 4, and the intake port 14 and the exhaust port 15 are respectively provided with an intake valve 16 and an exhaust valve 17. Are provided so as to be openable and closable (see FIG. 2). The tappet clearances of the intake valve 16 and the exhaust valve 17 are adjusted by shims.
[0013]
A camshaft 18 is arranged adjacent to the top ends of the intake valve 16 and the exhaust valve 17. One end (the left end in FIGS. 1 and 4) of the cam shaft 18 is rotatably supported by the cylinder head 4 and the cam shaft holder 20 via a cam shaft bearing 19a so as to be rotatable. The right end in FIGS. 1 and 4 is rotatably supported by the cylinder head 4 via a cam shaft bearing 19b. A driven sprocket 21 and a magnet holder 22 are sequentially superimposed on the one end of the cam shaft 18 and are integrally mounted by bolts 23. On the other hand, a drive sprocket 24 is provided integrally with the crankshaft 9, and an endless cam chain 25 is mounted on the drive sprocket 24 and the driven sprocket 21.
[0014]
As shown in FIGS. 2 and 6, a pair of rocker arm shafts 26 are arranged at the center between the tops of the intake valve 16 and the exhaust valve 17 and above the camshaft 18 with their axes horizontal. Both ends are fitted to the cylinder head 4 and the camshaft holder 20 (see FIGS. 5 and 7). A rocker arm 28 is pivotally supported on each of the pair of rocker arm shafts 26 so as to be swingable. A roller 29 is pivotally attached to one end of the rocker arm 28 and abuts on the cam ridge 18a of the cam shaft 18, and the other end abuts on the top of the intake valve 16 and the exhaust valve 17, respectively. Thus, when the internal combustion engine 1 is operating, the camshaft 18 is driven to rotate at half the rotation speed of the crankshaft 9, and the intake valve 16 and the exhaust valve 17 are opened and closed once each time the crankshaft 9 rotates twice. It is supposed to be.
[0015]
As described above, the rocker arm 28 is pivotally supported on the rocker arm shaft 26 so as to be swingable. As shown in FIGS. 5 and 7, the rocker arm 28 is mounted with a space provided in the axial direction. The collar 27 is inserted in the space. This collar 27 is made of resin and has a C-shaped cross section having a flange 27a at one end and a notch slit 27b parallel to the axis as shown in FIG.
[0016]
Reference numeral 40 in FIGS. 4, 5, 7, and 9 denotes a set plate for preventing the rocker arm shaft 26 from rotating, and reference numeral 42 denotes an elastic member for fixing the set plate 40. .
[0017]
Next, as shown in FIGS. 1 and 4, the magnet holder 22 integrally attached to one end (the left end in the figure) of the camshaft 18 has a small-diameter cylindrical shape at a position located on the inner diameter side of the driven sprocket 21. The outer portion is formed in a large diameter cylindrical shape. A plurality of permanent magnets 35 are integrally mounted on the inner peripheral surface of the large-diameter cylindrical portion at equal intervals in the circumferential direction.
[0018]
Further, a cooling water pump 30 is provided outside the camshaft 18 (to the left in FIGS. 1 and 4). A pump cover 31 of the cooling water pump 30 is fitted in an opening formed in a side wall of the cylinder head 4, and a base end of a pump body 32 is closely fitted in the pump cover 31. The cylindrical portion of the pump body 32 is formed so as to have a certain distance from the large-diameter cylindrical portion of the magnet holder 22. A pump shaft 33 is disposed on the rotation axis of the cam shaft 18, and both ends thereof are rotatably fitted to the pump cover 31 and the pump body 32. A rotor 34 is fitted on the pump shaft 33, and a permanent magnet 36 is integrally mounted on a cylindrical portion of the rotor 34 at a position corresponding to a permanent magnet 35 integrally mounted on the magnet holder 22. Have been. Further, a vane 37 is integrally formed outside (to the left of FIG. 4) of the cylindrical portion of the rotor 34. When the driven sprocket 21 is rotationally driven in this manner, the magnet holder 22 integrated therewith rotates, and the permanent magnet 36 integrally mounted on the rotor 34 of the cooling water pump 30 rotates with the permanent magnet 35 rotating with the magnet holder 22. And the cooling water pump 30 is driven to rotate.
[0019]
In such an internal combustion engine 1, when the fuel-air mixture supplied to the combustion chamber 13 is ignited, the fuel explosively burns and pushes down the piston 8. By operating the intake valve 16 and the exhaust valve 17 and repeating supply and exhaust and ignition in a predetermined order and timing, the piston 8 reciprocates. This movement of the piston 8 rotates the crankshaft 9 via the connecting rod 12, and is further transmitted to wheels (not shown). The rotation of the crankshaft 9 is transmitted to the camshaft 18 via a drive sprocket 24, a cam chain 25, and a driven sprocket 21, and further, via the cam ridge 18a and the rocker arm 28, the intake valve 16 and the exhaust valve 17 are set to a predetermined position. Opening and closing in the order and timing.
[0020]
When the shim is replaced to adjust the tappet clearance of the intake valve 16 or the exhaust valve 17, the collar 27 is removed from the rocker arm shaft 26 as shown in FIG. The collar 27 is provided with a notch slit 27b parallel to the axis. Therefore, by opening the notch slit 27b, the collar 27 can be easily attached to and detached from the rocker arm shaft 26. Then, as shown, the rocker arm 28 is moved in the axial direction on the rocker arm shaft 26, and the shim at the top 16a of the intake valve 16 or the exhaust valve 17 (for example, the intake valve) is replaced.
[0021]
As described above, in this embodiment, when the shim type tappet clearance adjustment is performed, the collar 27 is removed from the rocker arm shaft 26 without removing the rocker arm 28 or the rocker arm shaft 26 from the cylinder head 4 and the rocker arm 28 is removed. The shim can be replaced only by moving the shaft on the rocker arm shaft 26 in the axial direction, so that the workability is greatly improved.
[0022]
In the present embodiment, the axial movement of the rocker arm 28 can be prevented without increasing the inertial mass of the rocker arm 28 and without increasing the sliding resistance. Can be improved. Further, by making the collar 27 an elastic body, it is possible to suppress the tapping sound due to the axial movement of the rocker arm 28.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an internal combustion engine to which an embodiment of the present invention is applied, which is cut along a plane substantially passing through a crank axis and a cylinder axis.
FIG. 2 is a longitudinal sectional view similarly cut along a plane passing substantially through the cylinder axis and perpendicular to the crank axis.
FIG. 3 is a longitudinal sectional view similarly cut along a plane orthogonal to a crank axis near a cam chain.
FIG. 4 is an enlarged view showing an upper part of FIG. 1;
FIG. 5 is a view of the cylinder head viewed from above with a cylinder head cover removed.
FIG. 6 is a sectional view taken along the line VI-VI in FIGS. 5 and 7;
FIG. 7 is a sectional view taken along the line VII-VII in FIGS. 4 and 6;
8 is a view showing a collar 27 in FIGS. 5 to 7, in which (a) is a plan view, (b) is a front view, (c) is a bottom view, and (d) is (b) FIG.
9 is a view showing a state in which the collar 27 is removed from the state shown in FIG. 7 and the position of the rocker arm 28 is shifted.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2a ... Left crankcase, 2b ... Right crankcase, 3 ... Cylinder block, 4 ... Cylinder head, 5 ... Cylinder head cover, 6a ... Left crankcase cover, 6b ... Right crankcase cover, 7 ... Cylinder hole Reference numeral 8 piston, 9 crankshaft, 10 piston pin, 11 crank pin, 12 connecting rod, 13 combustion chamber, 14 intake port, 15 exhaust port, 16 intake valve, 17 exhaust valve, 18 ... cam shaft, 18 a ... cam ridge, 19 a, 19 b ... cam shaft bearing, 20 ... cam shaft holder, 21 ... driven sprocket, 22 ... magnet holder, 23 ... bolt, 24 ... drive sprocket, 25 ... cam chain, 26 ... Rocker arm shaft, 27 ... Collar, 27a ... Flange, 27b ... Notch slit, 28 ... Lock -Arm, 29 ... Roller, 30 ... Cooling water pump, 31 ... Pump cover, 32 ... Pump body, 33 ... Pump shaft, 34 ... Rotor, 35, 36 ... Permanent magnet, 37 ... Vane, 40 ... Set plate, 42 ... Elasticity Element.

Claims (2)

In a valve operating device for an internal combustion engine, the rotation of the intake / exhaust cam is transmitted to the intake / exhaust valve via a rocker arm, and the intake / exhaust valve is opened / closed at a predetermined timing.
A rocker arm positioning structure, wherein the rocker arm is swingably mounted on a rocker arm shaft and provided with a space in an axial direction, and a collar is inserted into the space. The rocker arm positioning structure according to claim 1, wherein the collar is made of a resin having a C-shaped cross section having a notch slit along the rocker arm axis.

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