JPH0240241Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is an engine valve train, in particular, an engine valve system in which each cylinder is provided with a plurality of at least one of intake and exhaust valves, and these valves are arranged at the upper part of a camshaft. The present invention relates to a valve train that is configured to be driven by provided camshafts via rocker arms.

(Prior art) In a valve train of the type in which a single camshaft installed at the top of the cylinder head drives the intake and exhaust valves of each cylinder, two rocker shafts are installed along both sides of the camshaft. At the same time, an intake valve rocker arm and an exhaust valve rocker arm are respectively supported on the shaft, and the valves are driven via these rocker arms. In that case, the rocker shaft is supported by cap members on the bearings of the camshaft provided at both ends of the upper part of the cylinder head and between each adjacent cylinder, as shown in, for example, Japanese Utility Model Application Publication No. 59-40506. It is customary to do so.

However, when the rocker arm opens the valve against the valve spring due to the rotation of the camshaft, the reaction force acts on this rocker shaft as an upward force, but especially if one or both of the intake and exhaust valves for one cylinder are In an engine equipped with a single rocker shaft, a plurality of rocker arms are supported between adjacent support parts of the rocker shaft, and the above-mentioned reaction forces act simultaneously from these rocker arms, so a large upward force acts on the rocker shaft. Become. As a result, the center portion of the rocker shaft between the adjacent support portions is deformed so as to bend upward, and as a result, an unreasonable load is applied to the attachment portion of the cap member that supports the shaft, noise is generated, etc. This results in the following problems. Since this phenomenon becomes more pronounced as the engine speed increases, it becomes a factor that prevents the engine from increasing its speed.

(Purpose of the invention) This invention deals with the above-mentioned problems in the engine valve system.
A plurality of at least one of the exhaust valves is provided,
Along with this, in a valve train in which a plurality of rocker arms are supported between adjacent support parts of a rocker shaft, by increasing the support rigidity of the rocker shaft, deformation of the shaft and generation of noise accompanying this can be suppressed. In addition, it is an object of the present invention to increase the rotation limit of the valve train to enable high rotation of the engine.

(Structure of the invention) That is, the engine valve train according to the invention has the following features:
In a configuration in which a plurality of at least one of intake and exhaust valves is provided and these valves are each driven via a rocker arm, a rocker shaft supporting each rocker arm is mounted at both ends of the upper part of the cylinder head and between each adjacent cylinder. The cap member is supported on the head using a cap member, and the cap members are connected to each other by a connecting portion passing above the rocker shaft, and a stop portion is provided on the lower surface of the connecting portion opposite to a location between the rocker arms in the rocker shaft. It is characterized by having the following. When the plurality of valves are opened, a large upward reaction force acts on the rocker shaft through the rocker arms, and as a result, the center portion of the shaft between the adjacent support parts deforms upward. When this happens, it comes into contact with the shaft and acts to prevent its deformation.

(Effect of the invention) As described above, according to the invention, the support rigidity of the rocker shaft is improved by providing the stopper portion that prevents upward deformation of the rocker shaft that has one cylinder and supports a plurality of rocker arms. It turns out. This prevents problems such as deformation of the rocker shaft, the generation of noise caused by this, or the application of an unreasonable load to the attachment part of the cap member that supports the rocker shaft, and also limits the rotation of the valve gear. This increases the engine speed and allows the engine to run at higher speeds.

(Example) Hereinafter, an example of the valve train according to the present invention will be described.

As shown in FIG. 1, one camshaft 2 is disposed at the center of the upper part of the cylinder head 1. As shown in FIG.
This camshaft 2 has bearing holes 3a...3a (see Fig. 2) in bearing walls 3...3 provided at both ends of the upper part of the cylinder head 1 and between each adjacent cylinder.
The journal portions 2a...2a are respectively fitted into the
It is rotatably supported by the head 1, and
Two intake cams 2b, 2b and one exhaust cam 2c for one cylinder are provided between adjacent journal parts 2a...2a. Further, one side of the cylinder head 1 is provided with two intake valves 4 for each cylinder, and the other side is provided with one exhaust valve 5 for each cylinder. For each cylinder, two intake valve rocker arms 6, 6 spanning the two intake cams 2b, 2b and the two intake valves 4, 4 in the camshaft 2, and one exhaust cam 2c, 1 one exhaust valve rocker arm 7 that straddles two exhaust valves 5;
These rocker arms 6, 6, and 7 have their center portions swingably supported by first and second rocker shafts 8, 9, respectively, which are disposed along the upper sides of both sides of the camshaft 2. has been done. Here, the rocker shafts 8, 9 have bearing walls 3...3 that support the camshaft 2 between both ends of the cylinder head 1 and each adjacent cylinder,
Bolts 10 and 10 are attached to the upper part of the bearing wall 3...3, respectively.
It is supported by cap members 11 . That is, as shown in FIG. 2, two semicircular recesses 3b and 11a are provided in corresponding positions on both sides of the upper surface of the bearing wall 3 and on both sides of the lower surface of the cap member 11, respectively. A first locking shaft 8 is held between the recesses 3b and 11a, and a second locking shaft 9 is held between the other recesses 3b and 11a. , 9a, so that these rocker shafts 8, 9 are inserted into the cylinder head 1.
is fixed.

The cap members 11 . . . 11 that support the first and second rocker shafts 8 and 9 at both ends of the cylinder head 1 and between each adjacent cylinder have connecting portions 12 that pass above the rocker shafts 8 and 9, respectively. Adjacent ones are connected by 13, and all the cap members 11...11 are integrated. As shown in FIG. 3, a stopper portion 12a projecting downward is provided on the lower surface of the center of the connecting portion 12 through which it passes. And this stopper part 12a
is opposed from above to the center between the adjacent support parts X, X of the first rocker shaft 8 located below, that is, to the location 8b between the two intake valve rocker arms 6, 6 supported on the shaft 8. There is.

The second rocker shaft 9 that supports one exhaust valve rocker arm 7 for one cylinder is equipped with a spacer 14 and a spring 15 on both sides of the rocker arm 7, so that the position of the rocker arm 7 is regulated by these. It's summery.

Next, the operation of the above embodiment will be explained.

When the camshaft 2 is rotated in synchronization with a crankshaft (not shown) during engine operation, two intake cams 2 provided on the camshaft 2
The intake valve rocker arms 6, 6 and the exhaust valve rocker arms 7, whose ends are in contact with b, 2b and one exhaust cam 2c, respectively, are swung around the first and second rocker shafts 8, 9, respectively. The intake valves 4, 4 and the exhaust valve 5, the upper ends of which are in contact with the other ends of these rocker arms 6, 6, 7, are opened at predetermined timings, respectively, against valve springs (not shown). At this time, the above cam 2
The force of pushing up one end of the rocker arms 6, 6, 7 by the rocker arms 6, 6, 7 and the reaction force of the valve spring act as upward forces on the first and second rocker shafts 8, 9, respectively, via the rocker arms 6, 6, 7. However, especially on the first rocker shaft 8 which supports two rocker arms 6, 6 between the adjacent support parts X, the above force is applied to both rocker arms 6, 6.
Since both act simultaneously, a larger force acts as a resultant force. Therefore, the first
The center portion 8b between the adjacent support portions X, X in the rocker shaft 8 tends to deform upward. but,
Above the central portion 8b of the rocker shaft 8, there is a connecting portion 12 that connects each cap member 11...11.
Since the stopper part 12a protruding from the lower surface of the rocker shaft is in contact with the stopper part 12a, when the rocker shaft center part 8b tries to deform upward, it is caught by the stopper part 12a. In other words, the rocker shaft 8 is also supported by the stopper portion 12a, and its support rigidity is increased.This prevents the deformation and the cap member 11 supporting the shaft 8. This prevents excessive loads from being applied to the attachment portion between the bearing wall 3 and the bearing wall 3, and from generating noise. In addition, by increasing the support rigidity of the rock shaft 8, the rotation limit of the valve train is improved,
This allows the engine to rotate at higher speeds.

The above embodiments relate to an engine in which one cylinder has two intake valves and one exhaust valve, but the present invention has only one intake valve.
The present invention can be similarly applied to an engine equipped with two exhaust valves, an engine equipped with two exhaust valves, an engine equipped with three or more exhaust valves, and an engine equipped with three or more exhaust valves.

Further, in the above embodiment, the entire bearing hole 3a into which the journal portion 2a of the camshaft 2 is fitted is formed in each bearing wall 3 provided at both ends of the cylinder head 1 and between adjacent cylinders. In other embodiments shown in FIGS. 4 and 5, only the lower half 3a' of the bearing hole is formed in the bearing wall 3', and bolts 10', 1
An upper half portion 11a' of a bearing hole is formed in a cap member 11' fixed by a screw 0'. In this embodiment, the rocker shaft 8',
9' is fitted and inserted, and each cap member 1
A hole 12b' is also formed in a stopper part 12a' protruding from the lower surface of one connecting part 12' that connects the connecting parts 1'...11', and the adjacent support part X', The central part 8b' between X', i.e. 1
The two rocker arms 6', 6' for the cylinder are fitted into the positions 8b'. Therefore, in this embodiment as well, the support rigidity of the rocker shaft 8' is improved, the upward deformation of the shaft center portion 8b' and the problems associated with this are prevented, and the rotation limit is increased. .

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, and FIG. 1 is a plan view of a valve train according to the embodiment;
2 and 3 are a longitudinal sectional front view and a side view of the main parts taken along the lines - and -, respectively, in FIG. 1. Also,
Figures 4 and 5 show the second embodiment, in which Figure 4 is a longitudinal sectional front view of the main part of the valve train, and Figure 5 is the figure 4-
FIG. 3 is a vertical sectional side view of the main part taken along a line. 1...Cylinder head, 4...Intake valve, 5
...Exhaust valve, 6,7,6'...Rotsuka arm,
8,9,8',9'...Lotsukashaft, 11,1
1'...Cap member, 12, 13, 12'...Connection part, 12a, 12a'...Stopper part.

Claims (1)

[Scope of utility model registration request] A valve operating system for an engine in which a cylinder is provided with a plurality of at least one of intake and exhaust valves and each of these valves is driven via a rocker arm, in which a rocker shaft that supports the rocker arm is located at both ends of the upper part of the cylinder head. and each adjacent cylinder is supported by the cylinder head using a cap member, and each of the cap members is connected by a connecting portion passing above the rocker shaft, and a rocker arm in the rocker shaft is connected to the lower surface of the connecting portion. 1. A valve operating device for an engine, characterized in that a stopper portion is provided in a protruding manner to prevent upward deformation of the shaft by coming into contact with a portion between the shafts.