JPH02230908A - Apparatus for forcedly opening/closing valve of internal combustion engine - Google Patents

Abstract

PURPOSE:To correctly transmit cam lift to a valve by a method wherein two branches are formed on one of interconnected rocker arms and these two branches are supported freely rockable on a spherical pivot. CONSTITUTION:A rocker arm 14 for closing a valve is formed with cam follower parts 15a, 15b which are brought in contact with two cams 3 for closing a valve respectively on tips of branches 12a, 12b formed in a fork shape. The intermediate portions of the branches 12a, 12b are supported freely rockable with spherical pivots 6a, 6b as supporting points which are provided along the axis of a cam shaft 1 with an interval. The branches can be stably supported without the rocker arm swinging right and left even with respect to a thrust car. Cam lift can thus be correctly transmitted to the valve as well as stability and quietness in a high speed rotation range can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a forced valve opening/closing device that forcibly opens and closes intake and exhaust valves of an internal combustion engine. (Prior technology) Mainly rM of intake and exhaust valves in engine high speed range.
In order to stabilize the leap characteristics, the camshaft is equipped with a valve-opening cam and a valve-closing cam to forcefully open and close the valve without relying on the valve spring. Mick), for example, JP-A-60-34
This method is disclosed in Publication No. 12, Japanese Patent Application Laid-Open No. 60-32910, etc. However, when one valve is driven by two cams, one for opening and one for closing, and two rocker arms that respond to these cams, the valve clearance must be adjusted for the opening and closing cams. Since it is necessary to perform each adjustment separately, there is a problem that the adjustment mechanism becomes complicated and the adjustment work becomes extremely troublesome. Therefore, the applicant proposed a solution to these problems in Japanese Patent Application No. 63-203521. In this system, a valve opening rocker arm and a valve closing rocker arm are swingably connected to each other, and one rocker arm is swingably supported with respect to the cylinder head via a spherical pivot. By adjusting the center of swing up and down, it is possible to simultaneously adjust the valve clearance for the valve-opening cam and the valve-closing cam, resulting in a significant improvement in the adjustment mechanism and FJ adjustment work. (Problem to be Solved by the Invention) However, in a normal valve train, the spherical pivot supporting the valve opening and valve closing rocker arms is single, so when a thrust force is applied to the rocker arm, it causes shaking and tilting. It was easy for this to occur, and the support stability of the rocker arm was lacking. Especially in the high rotation range, even the slightest vibration has a large effect on the overall vibration and noise, and also makes it difficult to accurately transmit cam lift to the valves. The present invention aims to solve such problems. (Means for Solving the Problems) The present invention provides a camshaft that rotates in synchronization with engine rotation with a valve-opening cam and a valve-closing cam, and provides contact response to the valve-opening cam via a cam follower. The valve-opening rocker arm is brought into contact with the valve shaft of the valve in the downward direction, and the valve-closing rocker arm, which comes into contact with each of the valve-closing cams via the cam follower, is also brought into contact with the valve shaft in the upward direction. One rocker arm is swingably supported in the middle of the other rocker arm, and two branch parts separated in the axial direction of the camshaft are formed on one of the rocker arms, and each branch part is connected to the cylinder head. It was supported so that it could swing freely via a pair of spherical pivots installed in the center. (Function) Therefore, the valve (intake/exhaust valve) is driven in the opening direction by the opening rocker arm that responds to the valve opening cam, and is returned to the closing direction by the valve closing rocker arm that responds to the valve closing cam. ．This is because the two branch parts formed on one of the rocker arms that are swingably connected to each other are swingably supported by a pair of spherical pivots that are spaced apart from each other in the axial direction of the camshaft. , it is possible to stably support the thrust force applied to the rocker arm without shaking from side to side, accurately transmit the cam lift to the valve, and suppress the occurrence of vibrations, resulting in stability and quietness in the high-speed rotation range. (Embodiments) The present invention will be explained below based on several embodiments. In the first embodiment shown in Figs. 1 and 2, numeral 1 in the figure is a camshaft; The shaft 1 has one valve opening cam 2 located above each valve (intake or exhaust valve) 4, and two valve opening cams 2 on both sides with the valve cam 2 in between.
The two valve-closing cams 3 are each integrally formed. The valve opening rocker arm 5 that contacts the valve opening cam 2 via the cam flange lower portion 5a has its swinging tip abutting portion 5b in contact with the end of the valve shaft 4a of the valve 4, and Its swinging base end is supported by a rocker arm 15 for valve closing via a support shaft 16, and while responding to the valve opening cam 2, the support shaft 1
Using 6 as a fulcrum, push down valve 4. On the other hand, the valve-closing rocker arm 15 has cam follower parts 15m and 15b that contact the two valve-closing cams 3 at the tips of the bifurcated branch parts 12a and 12b, respectively.
is formed, and the intermediate portions of the branched portions 12a and 12b are swingably supported around spherical pivots 6a and 6b disposed on the cylinder head 9 at intervals in the axial direction of the camshaft 1. A locking portion 15c at the swinging tip is attached to the valve shaft 4a or contacts (locks) the retainer 17 from below, and lifts the valve 4 according to the rotation angle position of the camshaft 1. In this embodiment, the spherical pivots 6a and 6b are constituted by a hydraulic adjuster 7, and are extended by the hydraulic pressure of lubricating oil supplied to a support hole 9a formed in the cylinder head 9, and automatically adjust the valve clearance to zero. do. These spherical pivots 6a, 6b are arranged at a predetermined interval in the axial direction of the camshaft 1, thereby preventing the valve closing rocker arm 15 from tilting. Note that when the valve-opening cam 2 pushes down the valve 4, the valve-closing cam 3 does not prevent this, and when the valve-closing cam 3 pulls up the valve 4, the valve-opening cam 2 does not prevent this. Each cam profile is formed so that
As a result, both the vertical movement of the valve 4 is driven by the cam without the need for a valve spring. By the way, in this embodiment, each valve has an oval shape with two intake valves or two exhaust valves, and therefore,
The abutting portions and locking portions of the rocker arms 5 and 15 with the valves 4 are branched into two corresponding to the two valves 4. Of course, in the case of a single valve 4, the abutting part and the locking part are single. It is constructed as described above, and its operation will be explained next. When the rocker arm 5 corresponding to the valve-opening cam 2 swings about the support shaft 16 as the camshaft 1 rotates, the tip of the valve 4 is pushed down by the abutment portion 5b at the tip to open the valve. Thereafter, the rocker arm 15 corresponding to the valve-closing cam 2 swings around the spherical pivots 6a and 6b, pulls up the valve 4 via the locking portion 15C, and closes the valve. In this way, the opening and closing of valve 4 is done by cams 2 and 3.
Since the conventional valve spring is not required, the valve 4 can be opened and closed stably without surging even in the high rotation range. Since the rocker arm 15 has branching parts 12a and 12b supported by two spherical pivots 6a and 6b arranged at a certain distance in the axial direction of the camshaft 1, even if a thrust force acts on the rocker arms 5 and 15, the rocker arm 15 does not tilt to the left or right and is always supported stably. Therefore, the cam lift characteristics can be accurately transmitted to the valve 4, and generation of vibration and noise can also be prevented. Regarding valve clearance, since the fulcrum of the rocker arm 15 is pushed up by the hydraulic adjuster 7, in the cam base circle, the cam follower portion 5a of the rocker arm 5 for valve opening and the cam follower portion of the rocker arm 15 for valve closing are separated. 15a and 15b are in close contact with the cam surface, respectively, and it is automatically compensated so that no clearance occurs. Next, in the second embodiment shown in FIG.
, 6b is equipped with an end pivot type adjustment screw 8, and by adjusting the height of the adjustment screw 8, the rocking center position of the rocker arm 15 can be adjusted, and the valve clearance can be made zero, 8a.
8b indicates a locking nut, 8b indicates a pivot seat, and 8c indicates a passage for supplying lubricating oil to the seat surface. Furthermore, in the embodiment shown in FIG.
Adjustment screws 8 as spherical pivots 6a and 6b are attached to the arms 13 on the left and right in this way.
By protruding the valve, it is possible to move the adjustment screw 8 closer to the valve 4, thereby making the valve mechanism more compact. (Effects of the Invention) As described above, according to the present invention, two branch parts are formed in one of the rocker arms that are connected to each other, and these two branch parts are arranged at a certain interval in the axial direction of the camshaft. Because the rocker arm is swingably supported by a pair of spherical pivots, the rocker arm can be stably supported without shaking from side to side even when subjected to thrust force, and the cam lift can be accurately transmitted to the valve while also reducing vibration. It is possible to improve stability and quietness in the high-speed rotation range by suppressing the occurrence of

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a sectional view of the second embodiment, and FIG. 4 is a plan view of a third embodiment. It is. 1... Camshaft, 2... Valve opening cam, 3... Valve closing cam, 4...
Valve (intake, exhaust valve), 5... Rocker arm, 5a.
...Cam 7 oror part, 6m, 6b...spherical pivot,
7... Hydraulic adjuster, 8... Adjustment screw 9... Schilling head, 12m, 12b... Branch, 13... Arm, 15... Rocker arm, 15a
...Cam 7 year old lower club. 1st Fig. 1 1 cam ift 2 1 to valve opening force 3 1 question valve cam 4 --- valve valve, exhaust valve) 5-11 rocker arm 5a = l muff opening? Anko 6a-One-sphere pivot 7--La music king a decision star 9--Ichigo somata 'a, Il' 12a One branch evil 15-11 Rocker arm 15a-1 Muforoana

Claims (1)

[Claims] A valve-opening cam and a valve-closing cam are provided on a camshaft that rotates in synchronization with engine rotation, and a valve-opening rocker arm that contacts and responds to the valve-opening cam via a cam follower is attached to the valve shaft of the valve. A valve-closing rocker arm that is brought into contact with the valve-closing cam in the pushing-down direction and responds to the valve-closing cam through the cam follower portion is also locked against the valve shaft from the pulling-up direction, and one rocker arm is placed in the middle of the other rocker arm. The camshaft is swingably supported, and one of the rocker arms is formed with two branch parts separated in the axial direction of the camshaft.
A valve forced opening/closing device for an internal combustion engine, characterized in that each branch portion is swingably supported via a pair of spherical pivots respectively disposed on a cylinder head.