JP2514649Y2 - Valve system rocker arm structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rocker arm structure for a valve train of an engine.

(Prior Art) An example of a valve train will be described with reference to FIG. Rocker arm 1 for intake valve and rocker arm 2 for exhaust valve
Are rotatably supported by rocker arm shafts 3 and 4, respectively. One end of each rocker arm 1, 2 1a, 2a
Are brought into contact with the cam shaft 5. Further, the adjusting screws 6 and 7 are screwed into the other ends 1b and 2b of each rocker arm. The contact surface at the end of the adjust screw 6 contacts the valve stem head 8a of the intake valve 8, and the contact surface at the end of the adjust screw 7 is the valve stem head 9a of the exhaust valve 9.
Is in contact with 1 valve spring for each valve
0 and 11 give the movement habit of closing each port. The rocker arms 1 and 2 sway as the cam shaft 5 rotates, and selectively open and close the valves 8 and 9 via the adjusting screws 6 and 7.

By the way, a four-valve system in which two intake valves and two exhaust valves are provided for each cylinder, and a three-valve system in which one exhaust valve and two intake valves are provided for one cylinder, respectively. The valve system has been put to practical use. An example with two intake valves will be described with reference to FIG. The intake valves are arranged on the same side as the fulcrum of the rocker arm, that is, on the rocker arm shaft 3. From the relationship of the valve layout with the cylinder head (not shown), the valve stems 8A and 8B are When viewed from the arrangement direction of the cylinders, they may be provided so as to be inclined so that the respective lift-direction center lines intersect at a certain point. That is, the valve stem heads 8aA and 8aB are different from each other in distance from the rocker arm shaft 3 which is the rotation center of the rocker arm. Therefore, the valve stem 8A
The same 8B is driven by rocker arms 1 and 1A with different arm lengths. Note that, in FIG. 4, the difference in arm length between the rocker arms 1, 1A (difference in installation position of the adjusting screw) is shown in a slightly exaggerated manner for convenience of explanation.

(Problems to be Solved by the Invention) As shown in FIG. 4, when a plurality of valves are arranged on one side of the rocker arm, these valves are
Since the rocker arm that drives each of them must be opened and closed, there is a problem in that a rocker arm with a different adjustment screw mounting position must be prepared, resulting in a costly valve operating system. Such a problem occurs not only in the center pivot type valve operating system shown in FIG. 4, but also in the end pivot type valve operating system.

Therefore, if the adjust screw is provided at a position where the distance from the rocking fulcrum of the rocker arm is made equal, it is considered that the parts can be shared, but when the rocker arm rocks, the arrow a in FIG. The contact surface of this (adjustment screw end surface) is the valve stem 8 as shown in.
Since A and 8B are pushed in the direction of twisting, there arises a problem that the smooth movement of the valve stem in the lift direction is hindered.

(Means for Solving the Problems) The present invention is intended to provide a rocker arm structure for a valve train that solves the above problems, and is a valve that is opened and closed by a rocker arm that contacts a valve stem head. In a rocker arm of a valve train, which is arranged on one side with respect to the fulcrum of the rocker arm and has a plurality of valves whose center lines in the lift direction intersect with each other when viewed from the cylinder arrangement direction. The substantial contact surface of the rocker arm that comes into contact with the valve stem head is formed by a curved surface whose center is substantially at the intersection with the center axis of each valve stem when the valve is closed.

(Operation) A rocker arm whose contact surface is formed into a curved surface having its intersection in the lift direction of the valve as its center substantially contacts the stem head of one valve. Also, other rocker arms of similar construction contact valve stem heads that differ in distance from the fulcrum of the arm.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.

FIG. 1 shows a center pivot type rocker arm. The rocker arm 20 is swingably supported by a rocker arm shaft 21 serving as a fulcrum, and one end 20a of the rocker arm 20 is in contact with a cam shaft 22.
An adjust screw 23 is screwed onto the other end 20b of the rocker arm 20 and is locked by a lock nut 24 after adjustment. Since it is fixed with the lock nut, the adjust screw 23 is attached to the rocker arm 20.
Is practically integrated with. The end of the adjust screw 23 is a contact surface 23a formed of a curved surface that contacts the stem head 25a of the valve stem 25. On the other hand, the rocker arm shaft 21 supports a rocker arm 20A having the same structure as the rocker arm 20, and the same end as the adjust screw 23 is screwed to the other end. When both rocker arms 20 and 20A are viewed from the cylinder arranging direction (the direction perpendicular to the paper surface), both arms are overlapped, so the adjustment screw provided on this arm is shown only on the front side. . Adjust screw 23
Is in contact with the stem head 25a of the valve stem 25 of one intake valve, and the other adjusting screw is in contact with the stem head 25Aa of the valve stem 25A of another intake valve. The valve stems 25, 25A intersect each other at an intersection X when the lift-direction center lines O1, O2 are viewed from the cylinder arrangement direction. The curved surface of the contact surface 23a of the adjusting screw is a curved surface having a radius R centered on the intersection point X.

The cam shaft 22 rotates and the rocker arm 20,20A
Is swung in the direction of the solid line arrow, the contact surface of the arm
23a (only one shown) for each valve stem head 25a, 2
The valve stems 25, 25A are brought into contact with 5Aa and pushed down in the direction of the solid line arrow to open the intake valve (not shown). When one end 20a of the rocker arm comes into contact with the base circle of the cam shaft 22, the rocker arm is swung in the direction of the broken arrow by the elastic force of a valve spring (not shown). In addition, in FIG.
The contact surface 23a of the adjust screw 23 is
The stems of the stems 25 and 25A are in contact with each other almost evenly, but the contact position without lift is taken into consideration in consideration of the change in the relative contact position between the contact surface and the stem head during valve lift. May be selected.

Next, referring to FIG. 2, another embodiment of the present invention will be described. This embodiment is an end pivot type valve train, in which the rocker arm 30 has one end 30a fitted to the auto lash adjuster 31 and the other end contact surface 30b formed on the valve stem. It is in contact with the head 32a.
A roller 33 is rotatably provided at a substantially central portion of the rocker arm 30, and is in contact with a cam shaft 34. The roller 33 is rotatably supported by the shaft 35. Another valve stem 32A that moves along the lift-direction center line O2 that intersects with the lift-direction center line O1 of the valve stem 32 is provided. When viewed from the axial direction of the cam shaft 34, another rocker arm for opening and closing the valve provided in the same cylinder is arranged on the opposite side of the rocker arm 30. The contact surface of is contacted with the valve stem head 32Aa. Contact surface 30b of these rocker arms
(Only one is shown) is formed on a curved surface having a radius R1 with the intersection X of the lift-direction center lines O1 and O2 of both valve stems 32 and 32A being substantially the center.

In the valve operating system of the type using the auto lash adjuster, the contact surface 30b can be made large, so that the contact surface with the valve stem heads 32a, 32Aa becomes large, and a stable valve lift action can be expected. Then, when the cam shaft 34 rotates, the rocker arm 30 (only one shown) swings with one end 30a as a swing fulcrum, and the contact surface 30b (only one shown) causes the valve stem head 32 to move.
The valve stem 32, 32A is pushed down by contacting a, 32Aa to open the valve (not shown).

If the substantial contact surface 30b of the rocker arm is formed into a curved surface with the intersection X in the lift direction of the valve stem as the approximate center, the distance from the rocking center of the rocker arm (see reference numeral 31) is different. Valve stem head 32a and 32Aa
Since the difference in contact friction with respect to can be made extremely small, it is possible to open and close a plurality of valves with one type of rocker arm. This also applies to the embodiment shown in FIG.

(Effects of the Invention) As described above, according to the present invention, the rocker arm for opening and closing the plurality of valves arranged on one side of the rocker arm swinging fulcrum can be made into a common component, so The cost of the valve system can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a front view of a rocker / car arm structure showing one embodiment of the present invention, and FIG. 2 is a front view showing another embodiment of the present invention,
FIG. 3 is a partially sectional front view showing an example of a valve train, and FIG. 4 is a front view showing an example of a conventional rocker arm structure. 8,9 …… Valve, 20,20A, 30 …… Rocker arm, 25a, 25
Aa, 32a, 32Aa ...... Valve stem head, 23a, 30b ......
Contact surface, X ... intersection.

Claims (1)

(57) [Scope of utility model registration request] 1. A valve that is opened and closed by a rocker arm that contacts a valve stem head, the valve being arranged on one side of a fulcrum of the rocker arm and viewed from the cylinder arrangement direction. In a rocker arm of a valve train having a plurality of valves whose center lines in the lift direction intersect with each other, the substantial contact surface of the rocker arm that contacts the valve stem head is centered when the valve is closed. -A rocker arm structure for a valve train, which is formed by a curved surface that is located at substantially the same position as the intersection of the central axis of the stem.