JP3526836B2 - Locking device for rocker arm shaft in valve train of internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating device for an internal combustion engine, which rockably supports a rocker arm connecting an intake / exhaust cam and an intake / exhaust valve. And a detent device for two rocker arm shafts. 2. Description of the Related Art In general, in a valve train for an internal combustion engine such as an SOHC type, two rocker arm shafts are juxtaposed at a certain interval to a cylinder head of an engine body, and these rocker arm shafts can swing respectively. The intake / exhaust cam and the intake / exhaust valve are connected by a rocker arm which is supported by the rocker arm, and the intake / exhaust valve is opened / closed at a predetermined timing by the rotation of the intake / exhaust cam. (See, for example, JP-A-2000-329002). In such a valve train, two rocker arm shafts on a valve train camshaft are supported by press-fitting or the like into rocker arm shaft holes formed in a cylinder head. For example, as shown in FIG.
Between the two rocker arm shafts, the central portion of the set plate is screwed to the cylinder head with a tightening bolt, and detents formed symmetrically on the lower surfaces at both ends of the left and right arms are provided on the two rocker arm shafts. The two rocker arm shafts are prevented from rotating by contacting the notches. However, in such a conventional rocker arm shaft detent means, when the set plate is tightened by the tightening bolt, the set plate is rotated in the tightening direction. A slight gap s is required between the notch of one rocker arm shaft located on the rear side in the tightening rotation direction and the detent part of the set plate, and the rocker arm shaft caused by the gap s during operation of the engine. There is a problem that a hitting sound is generated due to the idle rotation. Therefore, as a solution to this problem, 2
Each rocker arm shaft is provided with a separate detent set plate. An O-ring for preventing rotation is provided between each rocker arm shaft and the rocker arm shaft hole. [0007] Means such as
Not only does the number of parts increase and the cost increases, but it also occupies extra space and its layout is difficult.In addition, the above-mentioned method requires not only extra processing on the rocker arm shaft but also an increase in the number of parts and further assembly. There is another problem, such as the work is time-consuming. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel device for preventing rotation of a rocker arm shaft in a valve train for an internal combustion engine, which solves all of the above problems. . In order to achieve the above object, the present invention provides two rocker arm shafts arranged side by side on a cylinder head of an engine main body with a space therebetween. An exhaust cam and rocker arms that connect the intake and exhaust valves are swingably supported, and the intake and exhaust valves are opened and closed at predetermined timings by rotation of the intake and exhaust cams. In a valve operating device for an engine, an intermediate portion of a detent plate in which a first arm portion and a second arm portion are integrally extended is screwed to a cylinder head at an intermediate portion between the two rocker arm shafts. A member is fastened and fixed, and the first and second arms of the detent plate are
Engaging portions are respectively provided on the front side in the tightening rotation direction of the screw member, and these engaging portions are respectively engaged with engaged portions formed on the two rocker arm shafts in opposite directions. It is characterized in that the rocker arm shaft is prevented from rotating, and according to this feature, the two rocker arm shafts are accurately prevented from rotating by tightening and fixing the rotation preventing plate to the cylinder head with a screw member. Accordingly, it is possible to prevent the occurrence of a tapping sound due to idle rotation of the two rocker arm shafts during engine operation. Embodiments of the present invention will be described below based on embodiments of the present invention shown in the accompanying drawings. First, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine provided with a rocker arm shaft detent device in the valve train of the present invention, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIG. FIG. 4 is an enlarged sectional view taken along line 3-3 of FIG. 1, and FIG. 4 is a sectional view taken along line 4-4 of FIG. 1 and 2, an engine body E of an SOHC type air-cooled four-stroke internal combustion engine is fixed to a cylinder block 1 provided with a cylinder bore 2 and a deck surface of the cylinder block 1, and faces the cylinder bore 2. A cylinder head 3 having a combustion chamber 4 and a cylinder block 1
And a crankcase 5 fixed to the lower surface of the
The cylinder head 3 is provided with a valve operating device V, which will be described in detail later. A head cover 6 that covers the valve operating device V is mounted on the cylinder head 3. A piston 8 is slidably fitted to the cylinder bore 2 via a cylinder sleeve 7, and the piston 8 is connected to a crankshaft (not shown) via a connecting rod 10. The internal combustion engine is of a uniflow type, and an intake port 11 opening on one side and an exhaust port 12 opening on the other side are provided in the cylinder head 3 so as to face each other. 11 has an intake system In,
The exhaust system 12 is connected to the exhaust port 12. The intake port 11 is provided with an intake valve 13 that opens and closes an intake valve opening that communicates with the combustion chamber 4, and the exhaust port 12 opens and closes an exhaust valve opening that communicates this with the combustion chamber 4. An exhaust valve 14 is provided. Intake and exhaust valve 1
The valves 3 and 14 are held in the valve closing positions by the valve springs 15 and 16 as usual. An ignition plug 17 is screwed on a wall surface surrounding the combustion chamber 4 of the cylinder head 3, and its electrode faces the inside of the combustion chamber 4. A single valve operating camshaft 19 is provided at the center of the valve operating chamber formed on the cylinder head 3 with bearings 23 and 23.
It is rotatably supported via 24. An intake cam 20 and an exhaust cam 21 are integrally formed at an axially intermediate portion of the valve cam shaft 19. On one side (left side in FIGS. 2 and 3) of the cylinder block 1 and the cylinder head 3, a timing transmission chamber 25 is formed so as to straddle them. At one end (the left end in FIGS. 2 and 3) of the shaft 19, a timed driven gear 26 is fixed. The gear 26 is connected to a timed drive gear fixed to a crankshaft (not shown) via an endless timed chain 27. Linked and, as usual,
The rotation of the crankshaft is transmitted to the valve gear camshaft with a reduction ratio of 1/2. A bolt 28 that penetrates the side wall of the cylinder head 3 is inserted into the hollow valve camshaft 19, and a cover 29 that covers an opening of the timing transmission chamber 25 on the cylinder head 3 side is inserted into an end of the bolt 28. It is screwed. Two rocker arm shaft holes 30, 31 on the intake side and the exhaust side are formed in the cylinder head 3 on the left and right above the valve camshaft 19 in parallel with the valve camshaft 19. I have. As shown in FIG. 3, the rocker arm shaft holes 30 and 31 are formed as dead ends that open toward the timing transmission chamber 25. In this embodiment, the rocker arm shaft holes 31 on the exhaust side are connected to the intake side. The rocker arm shaft hole 30 is formed longer. The two rocker arm shaft holes 30, 31 have two hollow rocker arm shafts 32, 32 on the intake side and the exhaust side from the opening side.
33 is press-fitted. The two rocker arm shafts 32 and 33 support the intermediate portions of the rocker arms 34 and 35 on the intake side and the exhaust side, respectively, in such a manner that their positions are shifted in the axial direction. The outer end of the intake side rocker arm 34 is connected to the upper end of the intake valve 13 via a tappet 37, and the inner end thereof is a roller 39 which is rotatably supported there.
, And the outer end of the exhaust side rocker arm 35 is connected to the upper end of the exhaust valve 14 via a tappet 38,
The inner end thereof is connected to the cam surface of the exhaust cam 21 of the valve camshaft 19 via a roller 40 which is rotatably supported there. Therefore, according to the rotation of the valve operating camshaft 19, the rocker arms 34, 3 on the intake side and the exhaust side are provided.
5 swings around the rocker arm shafts 32 and 33, respectively, and cooperates with the valve springs 15 and 16 to make the intake valve 13
The exhaust valve 14 is opened and closed at a predetermined timing to operate the internal combustion engine. The two rocker arm shafts 32, 33 on the intake side and the exhaust side are rotated around the rocker arm shafts 30, 31 so as not to idle in the holes of the rocker arm shafts 30, 31 even by the operation of the valve train V. Stop means are provided. In other words, as shown in FIGS.
It is fastened and fixed. The detent plate 42 is formed integrally with a first arm 42a extending toward the intake side rocker arm shaft 32 and a second arm 42b extending toward the exhaust side rocker arm shaft 33. Is the valve operating camshaft 1
9 is formed on an arcuate concave surface substantially concentric. First and second arm portions 42a, 4 of the detent plate 42
2b, on the side surface of the front end of the rotation preventing plate 42 in the tightening rotation direction of the tightening bolt 43, an engaged portion 32 described later on the two rocker arm shafts 32, 33 is provided.
Flat engagement portions 42c and 42d capable of engaging with the first and second arm portions 33a and 33a are formed. As shown in FIG. On the other hand, the engaging portion 42d of the second arm portion 42b is
It is formed upward on the side surface of the end. Further, at one end of the two rocker arm shafts 32 and 33 corresponding to the detent plate 42, engaged portions 32a and 33a cut out in a semicircular shape are formed, respectively, as shown in FIG. Then, when the rotation preventing plate 42 is rotated in the tightening direction (the direction of the arrow a in FIG. 4) to tighten and fix the rotation preventing plate 42 to the cylinder head 3 with the tightening bolt 43, the rotation preventing plate 42 also moves in the same direction (the direction of the arrow b in FIG. 4). )
The engaging portions 42c, 4 at both ends of the rotation preventing plate 42
2d is engaged with the engaged portions 32a, 33a of the two rocker arm shafts 32, 32 without any gap. As described above, the two rocker arm shafts 32 and 33 are reliably prevented from rotating by the rotation of the screw member of the rotation preventing plate 42, that is, the tightening bolt 43, and the two rocker arm shafts are operated during operation of the engine. 3
It is possible to prevent occurrence of a tapping sound due to idle rotation of 2, 33. Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various embodiments are possible within the scope of the present invention. For example, in the above embodiment, the case where the rocker arm shaft detent device according to the present invention is applied to an SOHC type internal combustion engine has been described. However, this may be applied to another internal combustion engine having two rocker arm shafts. Of course. As described above, according to the present invention, in a valve train for an internal combustion engine having two rocker arm shafts in a cylinder head, the rotation of the two rocker arm shafts is stopped by the cylinder. The rotation can be reliably performed by the rotation preventing plate that is fastened and fixed to the head by the screw member, and it is possible to prevent the occurrence of a hitting sound due to the idle rotation of the two rocker arm shafts during the operation of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine having a rocker arm shaft detent device in a valve train of the present invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 1 FIG. 4 is a sectional view taken along line 4-4 in FIG. 1 FIG. 5 is a sectional view of a conventional valve train, which is the same as FIG. Explanation 3 Cylinder head 13 Intake valve 14 .... Exhaust valve 20 ... Intake cam 21 ... Exhaust cam 32 ... ... Rocker arm shaft 32a ... Engaged part 33 ... Rocker arm shaft 33a ... .... Engaged part 3 ... Rocker arm 35 Rocker arm 42 Detent plate 42a ... First arm 42b Second arm 42c -Engaging part 42d-Engaging part 43-Screw member (tightening bolt) E-・ ・ ・ ・ ・ ・ ・ ・ ・ Main body of engine

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2000-329002 (JP, A) JP-A-8-109810 (JP, A) JP-A 52-123215 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01L 1/18 F16B 1/02 F02F 1/24

Claims (1)

(57) [Claims] [Claim 1] Cylinder head (3) of engine body (E)
And two rocker arm shafts (32, 33) are juxtaposed at an interval.
33), rocker arms (34, 3) connecting the intake and exhaust cams (21, 22) and the intake and exhaust valves (13, 14).
5) are swingably supported, and the suction and exhaust cams (2) are supported.
The rocker arms (34, 35) are rotated by the rotation of (1, 22).
A valve operating device for an internal combustion engine in which the intake and exhaust valves (13, 14) are opened and closed at predetermined timings via a valve, wherein a cylinder is provided at an intermediate portion between the two rocker arm shafts (32, 33). The head (3) is fastened and fixed with a screw member (43) to an intermediate portion of a detent plate (42) in which a first arm (42a) and a second arm (42b) are integrally extended. The first and second arm portions (42a, 4a) of the detent plate (42)
2b), engaging portions (42c, 42d) are provided on the front side in the tightening rotation direction of the screw member (43), respectively.
These engaging portions (42c, 42d) are respectively engaged with engaged portions (32a, 32b) formed on the two rocker arm shafts (32, 33) in opposite directions.
A detent device for a rocker arm shaft in a valve train of an internal combustion engine, wherein detent of the rocker arm shafts (32, 33) is performed.