JPH02238108A - Compulsory valve opening/closing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make an engagement part thin and shorten the length of a valve by installing a reinforcing rib, free from the interference with a retainer or the oil seal of a valve guide, at the engagement part of a locker arm which is engaged from the undersurface onto the retainer of the valve. CONSTITUTION:A camshaft 1 equipped with one valve opening cam 2 and two valve closing cams 3 integrally is arranged in the upper position of a valve 4, and the contact part 5b at the swing top edge of a valve opening locker arm 5 which contacts the valve opening cam 2 through a cam follower part 5a is attached onto the top edge of the valve shaft 4a of the valve 4. Further, the engagement part 18 at the swing top edge of a valve closing locker arm 15 which contacts each valve closing cam 3 through cam follower parts 15a and 15b is attached from below a retainer 17 installed onto the valve shaft 4a through a ring type collet 17a. In such a compulsory opening/closing device, at the engagement part 18, each reinforcing rib 20 is projectingly installed at the both edges of the retainer 17 so as to surround the retainer 17, and the engagement part 18 can be made thin.

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) In order to stabilize the opening and closing characteristics of the intake and exhaust valves (valve) mainly in the high engine speed range, a valve opening cam and a valve closing cam are provided on the camshaft, and the valve spring is used to open and close the valve. For example, a device (desmodromic) that forcibly opens and closes a valve is disclosed in Japanese Patent Application Laid-Open No. 60-34.
This method is disclosed in JP-A No. 12, JP-A-60-32910, and the like.

However, in order to drive one valve with two cams for opening and closing the valve, and two rocker arms that respond to these cams, two rocker shafts are required, which takes up a large amount of space, making the valve mechanism difficult to operate. Because they were larger and the valve clearance had to be adjusted for each, the adjustment mechanism was complicated and the adjustment work was troublesome. Therefore, the applicant proposed a solution to these problems in Japanese Patent Application No. 63-203521. This allows the valve opening rocker arm and the valve closing rocker arm to be swingably connected to each other, and only one rocker arm is swingably supported relative to the cylinder head via a spherical pivot. By simplifying the design to reduce the space it occupies, and by adjusting the center of swing of the spherical pivot up and down, it is possible to adjust the valve clearance for the valve opening cam and valve closing cam at the same time. (Problems to be Solved by the Invention) In this valve operating system as well, the valve-closing rocker arm is engaged with the valve retainer from its lower surface, so the engagement portion interferes with the oil seal of the valve guard when the valve is lifted. In order to prevent this, a certain distance must be provided between the bottom surface of the rocker arm locking part and the oil seal, but as the thickness of the locking part increases, the distance from the bottom surface of the retainer to the oil seal also increases. Therefore, the valve stem must be lengthened accordingly, which increases the distance from the cam to the cylinder head upper deck, increases the engine height, and reduces sliding due to valve stem deflection. Problems such as deterioration of movement also occur.The present invention aims to solve such problems.

(Means for Solving the Problem) The present invention provides a valve opening cam and a valve closing cam 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. is brought into contact with the valve shaft of the valve in the downward direction, and the distal end locking portion of the valve-closing rocker arm, which is responsive to contact with each of the valve-closing cams, is locked in the upward direction with a retainer also attached to the valve shaft, In addition, reinforcing ribs are provided on both sides of the locking part, one rocker arm is swingably supported in the middle of the other rocker arm, and one of the rocker arms is swingably supported with respect to the cylinder head. .

(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 locking arm that responds to the valve closing cam. ．． The locking part of the rocker arm for closing the valve has reinforcing ribs on the left and right sides, so the wall thickness can be made thinner without compromising rigidity or strength. The distance between the valve guide oil seal and the valve guide oil seal can be shortened, making it possible to shorten the length of the valve stem. (Example) Examples of the present invention will be described below based on the drawings.

In the first embodiment shown in FIGS. 1 and 2, reference numeral 1 in the figures is a camshaft, and this camshaft 1 has a camshaft 1 located above each valve (intake or exhaust valve) 4. Two valve-opening cams 2 and two valve-opening cams on both sides sandwiching the valve-opening force 2.
The two valve-closing cams 3 are each integrally formed. The valve-opening rocker arm 5, which contacts the valve-opening cam 2 via the cam follower portion 5a, brings the abutment portion 5b at its swinging tip into contact with the end of the valve shaft 4a of the valve 4, and its swinging The moving base end is connected to a hydraulic adjuster 7 via a spherical pivot 6.
The valve 4 is pushed down using the spherical pivot 6 as a fulcrum while responding to the valve opening force 2. On the other hand, the valve-closing rocker arm 15 has cam follower parts 15a and 15b formed at its bifurcated ends to contact the two valve-closing force arms 3, respectively, and a cam It is swingably supported by a valve opening rocker arm 5 via a support shaft 16 parallel to the shaft 1. The locking portion 18 at the swinging tip of the rocker arm 15 is
It is attached to the valve shaft 4a via a ring-type collet 17a, or contacts (locks) the retainer 17 from the lower surface, and lifts up the valve 4 according to the rotation angle position of the valve-closing cam 3. As shown in FIGS. 3 and 4, reinforcing ribs 20 are provided on both sides of the retainer 17 so as to surround the retainer 17. As shown in FIGS. As a result, even if the wall thickness of the locking portion 18 is reduced, the rigidity and strength of the rocker arm 15 necessary for pulling up the valve 4 can be ensured, and the retainer 1
7 to the oil seal 14 attached to the valve guide 13 of the cylinder head 9. The hydraulic adjuster 7 is expanded by the hydraulic pressure of lubricating oil supplied to the support hole 9a formed in the cylinder head 9, and automatically adjusts the valve clearance to zero. 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. The ellipse is formed as described above, and the action will be explained next. When the rocker arm 5, which responds to the valve opening cam 2 as the camshaft 1 rotates, swings about the spherical pivot 6, the tip of the valve 4 is pushed down by the abutting portion 5b at the tip, opening the valve. Thereafter, the rocker arm 15 that responds to the valve-closing cam 2 swings about the support shaft 16, pulls up the valve 4 via the locking part 18, and closes the valve. In this way, all opening and closing of the valve 4 is performed by the cams 2 and 3, eliminating the need for conventional valve springs, so that surging does not occur even in the high rotation range.
Valve 4 can be opened and closed stably. The valve-closing rocker arm 15 that pulls up the valve 4 has a thin locking portion 18, and its rigidity and strength are provided by reinforcing ribs 20 on both sides, thereby preventing interference with the oil seal 14. It is possible to shorten the length of the valve shaft 4a of the valve 4 necessary for Can be done. In addition, by shortening the valve shaft 4a of the valve 4, the deflection of the valve shaft 4a during lift can be reduced and good sliding properties can be ensured. Regarding the valve clearance, since the fulcrum of the rocker arm 15 is pushed up by the hydraulic adjuster, in the cam base circle, the cam follower part 5a of the rocker arm 5 for valve opening, the cam follower part 15a of the rocker arm 15 for valve closing, 15b are in close contact with the cam surfaces, and the clearance is automatically compensated for.

Next, the embodiment shown in FIGS. 5 and 6 will be described. In this example, the reinforcing rib 20a formed on the locking portion 18 is
It protrudes downward so as to wrap around 4. In this case as well, the distance from the lower surface of the retainer 17 to the oil seal 514 can be shortened without causing interference with the oil seal 14. The embodiment shown in FIG. 7 is an example in which a guide block 23 is formed between the branched rocker arms 15 to prevent the rocker arms 15 from swinging from side to side when two valves 4 are driven simultaneously. When each intake valve (or exhaust valve) is provided with two intake valves (or two exhaust valves), the rocker arms 5 and 15 that drive the valve 4 have their tips branched into two, and there is an abutting part 5a and a locking part, respectively. 18 to open and close the two valves 4 at the same time. (Effects of the Invention) As described above, according to the present invention, a reinforcing rib is provided at the locking portion of the rocker arm that locks onto the valve retainer from below so as not to interfere with the retainer or the oil seal of the valve guide. As a result, the wall thickness of the locking part can be made thinner while ensuring the rigidity and strength of the rocker arm, and the required distance from the bottom surface of the retainer to the oil seal can be shortened.
The length of the valve can be shortened, which reduces the height from the cylinder head upper deck to the camshaft, making it possible to lower the overall height of the engine, and also prevents valve deflection and improves sliding performance. It is also possible to ensure gender.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the first embodiment of the present invention, FIG. 2 is a plan view, FIG. 3 is an enlarged sectional view of the rocker arm locking part, FIG. 4 is a perspective view, and FIG. An enlarged sectional view of a rocker arm locking portion of another embodiment, FIG. 6 is a perspective view as well,
FIG. 7 is an enlarged sectional view of yet another embodiment. 1...Camshaft, 2...Valve opening cam, 3...
Valve closing cam, 4... Valve (intake, exhaust valve), 5...
Rocker arm, 6... Spherical pivot, 7... Hydraulic adjuster, 15... Rotcalm, 17... Retainer, 18... Locking portion, 20... Reinforcement rib. 2nd cause Fig. 1 1--Item shaft 2-14 yen + mechanical i lift 3-1 closing valve 4-゛valve is also pre-prepared) 5.15-11 rocker arm 6-1 k-plane pivot 7--Yue Asiyasuta 17-11 Retire 18--One arc also L section 20-11 L button jf

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 comes into contact with the valve shaft of the valve in a downward direction. The end locking portion of the valve-closing rocker arm that contacts and responds to each of the valve-closing cams is locked from the lifting direction to a retainer also attached to the valve shaft, and reinforcing ribs are positioned on both sides of the locking portion. A valve forced opening/closing device for an internal combustion engine, characterized in that one rocker arm is swingably supported in the middle of the other rocker arm, and either one of the rocker arms is swingably supported with respect to a cylinder head.