JP4052964B2 - Locker arm shaft detent device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a detent device for a rocker arm shaft in a valve gear for an internal combustion engine.
[0002]
[Prior art]
Conventionally, a stopper for retaining a rocker arm shaft press-fitted into a rocker arm shaft hole has been disclosed (for example, see Patent Document 1). There was also a detent device for the rocker arm shaft as shown in FIG. This is formed symmetrically between the two rocker arm shafts 026, with the center portion of the set plate 040 screwed to the cylinder head 04 with a fastening bolt 023, and symmetrically on the lower surfaces of both end portions of the left and right arm portions of the set plate 040. The anti-rotation portion 040a is brought into contact with the notches 026a of the two rocker arm shafts 026 to prevent the rocker arm shafts 026 from rotating. In FIG. 8, reference numeral 018 denotes a cam shaft, and 019 denotes a cam shaft bearing.
[0003]
[Patent Document 1]
JP 2000-329002 A (paragraph 0041, FIGS. 6 and 7)
[Problems to be solved]
In the conventional anti-rotation device for the rocker arm shaft, when the set plate 040 is tightened by the tightening bolt 023, the set plate 040 rotates in the tightening direction, so that it is located behind the tightening rotation direction (left side in FIG. 8). A slight gap S is formed between the notch 026a of the one rocker arm shaft 026 and the rotation stopper 040a of the set plate 040. Therefore, there has been a problem that, during the operation of the internal combustion engine, a hitting sound is generated due to the rocking of the rocker arm shaft 026 caused by the gap S.
[0004]
[Means for solving the problems and effects]
In order to solve the above-mentioned conventional problems, the invention according to claim 1 is characterized in that a pair of rocker arm shafts are provided in the cylinder head of the internal combustion engine with a space therebetween, and an intake / exhaust cam, an intake / exhaust valve, In the valve operating apparatus for an internal combustion engine in which a pair of rocker arms connected to each other is supported by the rocker arm shaft so as to be swingable, notches that face each other are formed in each part of the pair of rocker arm shafts. and, between them cutout, insert the regulating member of the tapered shape which is tapered toward the direction in which the cross-sectional surface seen from the direction along the cam shaft is positioned in the crankshaft, the crankshaft by a cylinder head cover inner surface of the regulating member It presses toward the direction which is located, It is characterized by the above-mentioned.
[0005]
A first aspect of the present invention is constructed as described above, between the mutually facing notched portion of the rocker arm shaft, the tapered shape of the tapered toward the direction in which the cross section as viewed from the direction along the cam shaft is located in the crankshaft Since the restricting member is inserted and the restricting member is pressed by the inner surface of the cylinder head cover, the rocker arm shaft and the restricting member can be fixed to each other without looseness. Therefore, it is possible to prevent the occurrence of hitting sound and the wear of the bearing due to the rocking of the rocker arm shaft. In addition, since the restriction member is pressed and fixed by the cylinder head cover, the tightening bolt, screw hole machining step, and tightening step of the restriction member, which are necessary for the conventional rocker arm shaft detent device, can be omitted. But it will be advantageous.
[0006]
Next, the invention according to claim 2 is characterized in that, in the invention according to claim 1, the restricting member has a shape sandwiching a convex portion in the cylinder head in the cam shaft direction.
[0007]
Thus, in the invention described in claim 2, since the cam shaft direction position of the restricting member is regulated in a shape that sandwiches the convex portion in the cylinder head, it is possible to prevent wear due to the axial displacement of the rocker arm shaft. Further, since the restricting member is fixed using the existing convex portion, the position can be fixed without requiring any special processing on the cylinder head side.
[0008]
Next, the invention according to claim 3 is the invention according to claim 2, wherein an elastic member is disposed between the restriction member and the inner surface of the cylinder head cover, and between the restriction member and the convex portion. It is characterized by.
[0009]
In this way, in the invention described in claim 3, since the restricting member is fixed with the elastic member interposed therebetween, the restricting member can be reliably fixed. In addition, since the vibration of the cylinder head cover is absorbed by the elastic member, noise due to vibration is reduced.
[0010]
According to a fourth aspect of the present invention, in the invention according to the second or third aspect, the convex portion is a cam shaft holder, and the regulating member is in contact with an outer surface of the cam shaft bearing. It is characterized by this.
[0011]
As described above, according to the fourth aspect of the present invention, the restricting member is fixed at the cam shaft holder position and the position of the cam shaft bearing is also fixed. Durability is improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a longitudinal sectional view of an internal combustion engine to which an embodiment of the present invention is applied, cut along a plane substantially passing through a crank axis and a cylinder axis, and FIG. 2 is also cut along a plane passing substantially through the cylinder axis and perpendicular to the crank axis. FIG. 3 is a longitudinal sectional view taken along a plane perpendicular to the crank axis in the vicinity of the cam chain, and FIG. 4 is an enlarged view of the upper part of FIG.
[0013]
The internal combustion engine 1 is an overhead valve type four-stroke cycle single cylinder internal combustion engine, and its main body includes a left crankcase 2a, a right crankcase 2b, a cylinder block 3, a cylinder head 4, and 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 combined with each other, and the cylinder block 3, the cylinder head 4, and the cylinder head cover 5 are sequentially stacked thereon. Further, the left crankcase cover 6a is fitted to the left side surface of the left crankcase 2a, and the right crankcase cover 6b is fitted to the right side surface 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 coupled to each other with bolts or the like.
[0014]
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 in the left and right crankcases 2a and 2b. It is pivotally supported by. Then, both ends of a connecting rod 12 are pivotally attached 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 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.
[0015]
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. The intake port 16 and the exhaust port 15 are respectively connected to the intake valve 16 and the exhaust valve 17. Is provided so as to be freely opened and closed (see FIG. 2).
[0016]
A cam shaft 18 is disposed adjacent to the top ends of the intake valve 16 and the exhaust valve 17. One end portion (left end portion in FIGS. 1 and 4) of the cam shaft 18 is rotatably supported by being sandwiched between the cylinder head 4 and the cam shaft holder 20 via a cam shaft bearing 19a. (The right end in FIGS. 1 and 4) is pivotally supported by the cylinder head 4 via a camshaft bearing 19b. A driven sprocket 21 and a magnet holder 22 are sequentially stacked on one end of the camshaft 18 and are integrally mounted with bolts 23. On the other hand, a drive sprocket 24 is integrally provided on the crankshaft 9, and an endless cam chain 25 is mounted on the drive sprocket 24 and the driven sprocket 21.
[0017]
Further, as shown in FIG. 2, a pair of rocker arm shafts 26 are arranged with their axes in the middle between the tops of the intake valve 16 and the exhaust valve 17 and the upper portion of the camshaft 18, both of which have both ends. The cylinder head 4 and the camshaft holder 20 are fitted. A rocker arm 28 is pivotally supported by 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 is in contact with the cam crest 18a of the cam shaft 18, and the other ends are in contact with the tops of the intake valve 16 and the exhaust valve 17, respectively. Thus, during operation of the internal combustion engine 1, the camshaft 18 is rotationally driven at half the rotational speed of the crankshaft 9, and the intake valve 16 and the exhaust valve 17 are each opened and closed once each time the crankshaft 9 rotates twice. It has come to be.
[0018]
As shown in FIGS. 1 and 4, the magnet holder 22 that is integrally attached to one end (the left end in the figure) of the camshaft 18 is formed in a small-diameter cylindrical shape at a position located on the inner diameter side of the driven sprocket 21. Further, it is formed into a large-diameter cylindrical shape at the outer portion. A plurality of permanent magnets 35 are integrally mounted on the inner peripheral surface of the large-diameter cylindrical portion at equal intervals over the circumferential direction.
[0019]
Further, a cooling water pump 30 is disposed outside the cam shaft 18 (left side in FIGS. 1 and 4). A pump cover 31 of the cooling water pump 30 is fitted into an opening formed in the side wall of the cylinder head 4, and a base end of a pump body 32 is closely fitted to the pump cover 31. The cylindrical part of the pump body 32 is formed so as to have a certain distance from the large-diameter cylindrical part of the magnet holder 22. A pump shaft 33 is disposed on the rotation axis of the cam shaft 18, and both ends of the pump shaft 33 are rotatably fitted to the pump cover 31 and the pump body 32. A rotor 34 is fitted to the pump shaft 33, and a permanent magnet 36 is integrally attached to a cylindrical portion of the rotor 34 at a position opposite to the permanent magnet 35 integrally attached to the magnet holder 22. Has been. Further, a vane 37 is integrally formed so as to be located outward (leftward in FIG. 4) from the cylindrical portion of the rotor 34. Thus, when the driven sprocket 21 is driven to rotate, the magnet holder 22 integrated therewith rotates, and the permanent magnet 36 integrally attached to the rotor 34 of the cooling water pump 30 rotates with the magnet holder 22. Thus, the cooling water pump 30 is driven to rotate.
[0020]
5 is a view of the cylinder head 4 as viewed from above with the cylinder head cover 5 removed, FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5, and FIG. 7 is a sectional view taken along the line VII-VII in FIG. FIG.
[0021]
In the present embodiment, a notch 26a is formed at one end of the pair of rocker arm shafts 26 (left end in FIG. 5, lower end in FIG. 7) facing each other. And between them notches 26a, as shown in FIG. 6, the set plate 40 of tapered shape which is tapered toward the direction in which the cross-sectional surface viewed from the camshaft 18 direction is the position of the crankshaft, the regulating member Is inserted from above. As shown in FIGS. 4 and 6, the lower end of the set plate 40 is in contact with the outer ring outer surface of the camshaft bearing 19 a, and the upper part is a convex portion in the cylinder head 4 that is bent horizontally. The camshaft holder 20 extends upward and then bends downward to sandwich the camshaft holder 20. An elastic member 42 such as rubber is disposed between the set plate 40 and the cam shaft holder 20 and between the set plate 40 and the inner surface of the cylinder head cover 5 and is pressed by the cylinder head cover 5.
6 indicates the free shape of the elastic member 42 and is pressed when the cylinder head cover 5 is attached to the shape shown in FIG. Further, reference numeral 27 in FIGS. 5 and 7 denotes a collar arranged so that the axial position of the rocker arm 28 is not shifted.
[0022]
In such an internal combustion engine 1, when the fuel / air mixture supplied to the combustion chamber 13 is ignited, the fuel is combusted, the pressure in the combustion chamber 13 is increased, and the piston 8 is pushed down. The piston 8 reciprocates by operating the intake valve 16 and the exhaust valve 17 and repeating supply / exhaust and ignition in a predetermined sequence and timing. This movement of the piston 8 is rotated by the crankshaft 9 through the connecting rod 12 and further transmitted to a wheel or the like (not shown). The rotation of the crankshaft 9 is also transmitted to the camshaft 18 via the drive sprocket 24, the cam chain 25, and the driven sprocket 21, and further, the intake valve 16 and the exhaust valve 17 are passed through the cam crest 18a and the rocker arm 28. It opens and closes in the order and timing.
[0023]
In this embodiment, the direction of forming the notches 26a facing each other at one end of a pair of rocker arm shaft 26, the cross-sectional surface viewed from the camshaft 18 direction therebetween notch 26a is positioned in the crankshaft The taper-shaped set plate 40 tapering toward the center is inserted toward the crankshaft and the set plate 40 is pressed by the inner surface of the cylinder head cover 5, so that the rocker arm shaft 26 and the set plate 40 Can be fixed to each other without looseness.
Therefore, it is possible to prevent the occurrence of hitting sound and wear of the bearing due to the rocking of the rocker arm shaft 26. Further, since the set plate 40 is pressed and fixed by the cylinder head cover 5, the set plate tightening bolt, screw hole machining step, and tightening step, which are necessary for the conventional locking device for the rocker arm shaft, can be omitted. This is also advantageous in terms of cost.
[0024]
In this embodiment, the set plate 40 has a shape sandwiching the cam shaft holder 20 and restricts the position of the set plate 40 in the cam shaft 18 direction, so that wear due to the axial displacement of the rocker arm shaft 26 is also prevented. The Further, since the set plate 40 is fixed using the existing camshaft holder 20, the position can be fixed without special processing on the cylinder head 4 side.
[0025]
In this embodiment, the elastic member 42 such as rubber is disposed between the set plate 40 and the camshaft holder 20 and between the set plate 40 and the inner surface of the cylinder head cover 5. It can be fixed securely. Further, since vibration of the cylinder head cover 5 is absorbed by the elastic member 42, noise due to vibration is reduced.
[0026]
Further, in this embodiment, the lower end of the set plate 40 is in contact with the outer surface of the outer ring of the camshaft bearing 19a, so that the camshaft bearing 19a is free from rattling and the durability is improved.
[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, cut along a plane substantially passing through a crank axis and a cylinder axis.
FIG. 2 is a longitudinal sectional view taken along a plane which passes through the cylinder axis and is orthogonal to the crank axis.
FIG. 3 is a longitudinal sectional view taken along a plane perpendicular to the crank axis near the cam chain.
FIG. 4 is an enlarged view showing an upper part of FIG. 1;
FIG. 5 is a view of the cylinder head as viewed from above with the cylinder head cover removed.
6 is a cross-sectional view taken along arrow VI-VI in FIG. 5;
7 is a sectional view taken along arrows VII-VII in FIGS. 4 and 6. FIG.
FIG. 8 is a view showing an example of a conventional locking device for a rocker arm shaft.
[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 8 ... piston, 9 ... crankshaft, 10 ... piston pin, 11 ... crankpin, 12 ... connecting rod, 13 ... combustion chamber, 14 ... intake port, 15 ... exhaust port, 16 ... intake valve, 17 ... exhaust valve, 18 ... cam shaft, 18a ... cam crest, 19a, 19b ... 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, 26a ... notch, 28 ... rocker 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 ... elastic member.

Claims (4)

A pair of rocker arm shafts are provided in the cylinder head of the internal combustion engine at a distance from each other, and the pair of rocker arms that connect the suction / exhaust cam and the suction / exhaust valve are respectively swung by the rocker arm shaft. In a valve system of an internal combustion engine supported in a possible manner,
Each part of the rocker arm shaft of the pair, to form a cutout portion facing each other, between which cutout portion, tapered towards the direction in which the cross-sectional surface seen from the direction along the cam shaft is located in the crankshaft bets An anti-rotation device for a rocker arm shaft, wherein a taper-shaped restriction member is inserted, and the restriction member is pressed toward the crankshaft by the inner surface of the cylinder head cover.   2. The rocker arm shaft detent device according to claim 1, wherein the regulating member has a shape that sandwiches a convex portion in the cylinder head in the cam shaft direction.   The rocker arm shaft detent device according to claim 2, wherein an elastic member is disposed between the regulating member and the inner surface of the cylinder head cover and between the regulating member and the convex portion.   4. The rocker arm shaft detent device according to claim 2, wherein the convex portion is a cam shaft holder, and the restricting member is in contact with an outer surface of the cam shaft bearing.

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