JPH0113762Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a valve operating system for a multi-cylinder internal combustion engine using a rocker arm, and particularly relates to an improvement of the rocker shaft portion that supports the rocker arm.

Figures 1 and 2 show a camshaft 1 connected to a cylinder head 2 as an example of a conventional rocker arm type valve operating system.
This shows an example of a so-called SOHC type valve operating device disposed on the upper part of the engine, in particular, rocker shafts 3, 3 are provided on the intake side and exhaust side, respectively, and the intake and exhaust valves 4, 4 are arranged in a V-shape. The camshaft 1 has a plurality of cam bracket parts 6 which are integrally installed with the cylinder head 2 and installed between the respective cylinders 5, and a journal part 1, respectively.
a is fitted and rotatably supported. Further, the rocker shaft 3 supporting the rocker arm 7 is generally formed into a hollow tube shape in order to use the inside as a lubricating oil passage 8. It is fixedly supported by the support portion 9 with bolts 10 . The main body of the cylinder head 2 is not shown in FIG. 2, and the upper part of the figure shows the intake side valve mechanism, and the lower part shows the exhaust side valve mechanism.

However, in the conventional configuration using the rocker shaft 3 that is continuous over the entire length of the multi-cylinder engine, the rocker shaft 3 vibrates due to the reaction force from the rocker arm 7 that occurs when the intake/exhaust valves 4 are driven. easy. Further, since the rocker shaft support portion 9 that supports the rocker shaft 3 is erected in a simple flat plate shape together with the cam bracket portion 6, the tilting rigidity in the front and rear direction is low. Therefore, it has been found that vibrations from the rocker shaft 3 are propagated to various parts such as the cylinder head 2, and become a major cause of noise generated from the so-called valve system.

This idea was made in view of the above-mentioned drawbacks of the conventional technology, and its purpose is to effectively suppress the vibration of the rocker shaft that supports the rocker arm, and to reduce the valve train noise caused by this vibration. The goal is to reduce the

That is, the valve operating system for an internal combustion engine according to this invention is constructed by dividing the rocker shaft arranged parallel to the camshaft into a plurality of pieces in the longitudinal direction in a multi-cylinder internal combustion engine, while supporting the rocker shaft integrally with the cylinder head. A pair of rocker shaft support parts are connected to one cam bracket part via an arm part which forms a part and a cam bracket part and extends in a bifurcated shape from the side end of the cam bracket part. It is characterized in that both ends of each rock shaft are fixedly supported.

Hereinafter, a specific embodiment of this invention will be described in detail based on the drawings.

FIG. 3 is a top view of a cylinder head showing an embodiment of this invention, in which 11 is a camshaft, 2
Reference numeral 1 designates a cam bracket portion that rotatably supports this camshaft 11. This cam bracket portion 21 is located between the bores of each cylinder 13 and is integrally cast into the cylinder head, and has a cam bracket portion 21 on each side. Each pair of rocker shaft support parts 22, 22 are provided. This rock shaft support part 22
are also integrally cast into the cylinder head, and are located symmetrically around the cam bracket part 21 and diagonally from the side end of the cam bracket part 21, as shown in detail in FIG. It is connected to the cam bracket section 21 via an arm section 23 extending in a bifurcated manner. That is, a pair of rocker shaft support parts 22 are integrally formed with one cam bracket part 21 and a pair of arm parts 23 on the cylinder head. Although the illustrated example has five cam bracket parts 21 #1 to #5, rocker shaft support parts 22 are arranged alternately on the right and left, that is, on the intake side and the exhaust side. The rocker shaft support portions 22 at both front and rear ends of the engine are located on an extension line of the cam bracket portion 21.

The exhaust side rocker shaft 15 disposed parallel to the camshaft 11 includes a first rocker shaft 15A having a length approximately equal to the bore pitch and supporting the exhaust side rocker arms 16a, 16b of the #1 and #2 cylinders; The second rocker shaft 15B, which also has a length approximately equal to a bore pitch, supports the exhaust side rocker arms 16c and 16d of the #4 cylinder, and is divided into two parts in the longitudinal direction. The cam bracket portions #2 and #4 are fixedly supported by bolts 17 to a pair of rocker shaft support portions 22 on the sides of the cam bracket portions 21, respectively.

Similarly, the intake side rock shaft 18 is
An extremely short first rocker shaft 18A that supports only the intake side rocker arm 19a of the #1 cylinder;
#2, #3 cylinder intake side rocker arm 19b, 1
The second rocker shaft 18B is approximately the same length as a bore pitch and supports the rocker shaft 9c, and the third rocker shaft 18c is extremely short and supports only the intake rocker arm 19d of the #4 cylinder. and each rock shaft 18
A, 18B, 18C have both ends #1,
The #3 and #5 cam brackets 21 are fixedly supported by bolts 17 to a pair of rocker shaft support portions 22 on the sides of the cam bracket portions 21, respectively.

In other words, one cam bracket part 21 has one
It is arranged to support book lock shafts 15A to 18C. In addition, in Figure 4, 24
indicates a blind plug.

In the valve train configured as above,
Since the rocker shafts 15 and 18 are divided into a plurality of pieces and each shortened individually as described above, the rigidity against bending vibration is higher than that of a conventional continuous rocker shaft, and the rocker arms 16 and 19 are prevented from moving when the intake and exhaust valves are driven. Rotsukashaft 1 due to the reaction force of
5 and 18 are significantly suppressed. Also, the fourth
As shown in the figure, since the rocker shaft support part 22 is connected to the cam bracket part 21 via the arm part 23 that extends diagonally into two branches, the rigidity of the rocker shaft support part 22 in the front and back direction is dramatically improved. , it becomes difficult to vibrate back and forth even when receiving the excitation force from the rock shafts 15 and 18. Therefore, Rotsukashaft 1
Coupled with the fact that 5 and 18 are divided, it is possible to suppress the vibrations transmitted to each part of the cylinder head, and the valve train noise generated due to this can be significantly reduced.

The lubrication between each rocker shaft 15, 18 and each rocker arm 16, 19 can be achieved by forming a lubricating oil passage in the cam bracket portion 21 and the rocker shaft support portion 22, for example.
It may be configured to supply lubricating oil to the sliding portion from inside, or lubrication may be performed by dispersing oil mist.

Furthermore, in both of the above embodiments, an example was shown in which the present invention was applied to a SOHC type valve train having rocker shafts on the intake side and the exhaust side, but it goes without saying that the present invention is not limited to this. be.

As is clear from the above explanation, in the valve train for an internal combustion engine according to this invention, the rocker shaft that supports the rocker arm is divided into a plurality of parts in the longitudinal direction and shortened individually, thereby replacing the conventional continuous rocker shaft. Compared to the case where the rock shaft is used, the vibration of the rock shaft can be suppressed, and the longitudinal tilting rigidity of the rock shaft support part that supports each rock shaft can be greatly increased. Valve system noise can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a cylinder head showing a conventional valve train, Fig. 2 is a top view thereof, Fig. 3 is a top view of a cylinder head showing an embodiment of this invention, and Fig. 4 is its main parts. FIG. 11...Camshaft, 15...Exhaust side rock shaft, 18...Intake side rock shaft, 21
...Cam bracket part, 22...Rock shaft support part, 23...Arm part.

Claims (1)

[Scope of utility model registration request] In a multi-cylinder internal combustion engine, the rocker shaft arranged parallel to the camshaft is divided into a plurality of parts in the longitudinal direction, while the rocker shaft support part and the cam bracket part are integrally formed in the cylinder head, and the rocker shaft part is formed on the cam bracket part side. A pair of rocker shaft support parts are connected to one cam bracket part via an arm part extending in a bifurcated shape from the end,
A valve operating system for an internal combustion engine, characterized in that both ends of each rock shaft are fixedly supported by the pair of rock shaft support parts.