JPS5910322Y2 - Tappet noise reduction device for internal combustion engines - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an internal combustion engine in which intake and exhaust valves are opened and closed via tappets by rotation of a camshaft.
This invention relates to a device for reducing tappet noise when an exhaust valve comes into contact with a valve stem.

Conventionally, a four-cycle side valve type internal combustion engine as described above has a tappet chamber that communicates with the crank chamber through a gas vent passage, as seen in, for example, Japanese Utility Model Application Publication No. 51-144630. It is known that the tappet chamber is connected to the downstream side of the filter element of the air cleaner through a blow-by gas discharge path.

However, this internal combustion engine has a problem in that impact noise is loud when the tappet comes into contact with the valve stems of the intake and exhaust valves.

In order to improve this, efforts have been made to reduce the clearance between the tappet and the valve stems of the intake and exhaust valves, and to weaken the impact by changing the shape of the intake and exhaust cams installed on the camshaft. It has been difficult to sufficiently reduce impact noise.

The present invention was developed in view of the above-mentioned circumstances, focusing on the fact that lubricating oil is separated from blow-by gas in the tappet chamber of the internal combustion engine described above. It is an object of the present invention to provide a tappet noise reduction device that can effectively reduce impact noise between a tappet and a valve stem of an intake or exhaust valve.

In order to achieve this purpose, the tappet sound reduction device of the present invention provides an auxiliary tappet chamber below the main tappet chamber, which communicates with the crank chamber side through a gas vent passage, in the internal combustion engine as described above. Alternatively, the contact part between the tappet and the valve stem of the intake/exhaust valve is accommodated in the sub-tapppet chamber, the main tappet chamber is communicated with the blow-by gas discharge passage, and the sub-tappet chamber is separated from the blow-by gas within the main tappet chamber. It is designed to store lubricating oil.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In the figure, reference numeral 1 denotes a crankcase that is integrally formed with the cylinder block. A crank chamber 2 is formed in the lower part of the crankcase 1, and a cylinder liner 3 fitted to the upper part of the crankcase 1 has a Slidably piston 4
are fitted.

A camshaft 5 is installed in the crank chamber 2, and this camshaft 5
The lower end of a tappet 7 is supported by an intake cam 6 provided at the intake cam 6, and the tappet 7 is slidably supported by an upper wall 8 of the crank chamber 2.

A lower end of a valve stem 10 of an intake valve 9 is supported on the tappet 7, and the intake valve 9 is urged downward by a valve spring 11.

The above structure is the same as that of a normal four-cycle side valve type internal combustion engine.

A main tappet chamber 12 is formed above the crank chamber 2, and this main tappet chamber 12 is communicated with the crank chamber 2 side through a gas vent passage 13.

An auxiliary tappet chamber 15 is formed below the main tappet chamber 12 and above the crank chamber 2, which is partitioned from the main tappet chamber 12 by a partition wall 14. It communicates with the main tappet chamber 12 by a connecting passage 16.

A contact portion between the tappet 7 and the valve stem 10 of the intake valve 9 is housed in the sub-tappet chamber 15, and the main tappet chamber 12
The valve spring 11 is housed inside the valve spring 11, and both ends of the spring 11 are supported by an upper wall 18 of the main tappet chamber 12 and a spring retainer 19 provided on the valve stem 10. It is supported by 20 people.

In addition, the main and sub-tappet chambers 12. A breather plate 21 and a substantially dish-shaped tappet chamber cover 22 provided on the outside of the breather plate 21 are fastened together with bolts 23 to the open outer surface of the breather plate 15. A reed valve 25 is provided to open and close this, and one end of the reed valve 25 is fixed to a breather plate 21, and an oil barrier is provided on the inner surface of the breather plate 21 to prevent a short path between the discharge port 24 and the gas vent passage 13. A plate 26 is fixed.

The inside of the tappet chamber cover 22 communicates with a blow-by gas discharge passage 27, and this discharge passage 27 communicates with a downstream portion of a filter element of an air cleaner (not shown).

In addition, the reference numeral 17 in FIG. 2 indicates the valve stem of the exhaust valve, and although most parts are omitted from the illustration, the exhaust valve side is constructed in substantially the same way as the intake valve side described above, and the tappet and valve stem are A contact portion is installed in the sub-tappet chamber 15.

The tappet sound reduction device constructed as described above has the camshaft 5.
As the intake cam 6 rotates, the tappet 7 is pushed up, and the tappet 7 compresses the valve spring 11 and pushes up the valve stem 10, opening the intake valve 9. Then, the valve spring 11 expands and the intake valve opens. 9 is closed, its valve stem 10 descends to push down the tappet 7, and this operation is repeated.

Further, when the piston 4 descends, the internal pressure of the crank chamber 2 becomes positive, and the blow-by gas containing lubricating oil enters the main tappet chamber 12 from the crank chamber 2 side through the gas vent passage 13.

The blow-by gas that has entered the main tappet chamber 12 is depressurized to separate the lubricating oil, and the separated lubricating oil passes through the communication path 16.
People are stored in the sub-tappet chamber 15.

On the other hand, the blow-by gas from which the lubricating oil has been separated is transferred to the reed valve 2.
5 is opened, the air passes through the tappet chamber cover 22 from the discharge port 24, and is guided into the air cleaner via the discharge passage 27.

As described above, when the lubricating oil is stored in the sub-tapppet chamber 15, the contact portion between the tappet 7 and the valve stem 10 of the intake valve 9 is immersed in the lubricating oil, and the lubricating oil enters the clearance between them, causing the tappet 7 to It acts as a damper when the valve stem 10 and the valve stem 10 come into contact, and the shock at the time of contact is alleviated, thereby reducing impact noise.

In the same manner as on the intake valve side described above, on the exhaust valve side, the impact noise between the valve stem and the tappet is reduced by the lubricating oil.

Although the present invention has been described in the above-described embodiments in which the crankcase and cylinder block are integrally formed, the present invention can also be applied to systems in which these are separate bodies.

Further, when lubricating oil overflows from the sub-tappet chamber, the lubricating oil may be returned to the oil pan provided at the lower part of the crankcase by other appropriate means without using the gas vent passage.

As explained above, the tappet sound reduction device of the present invention is
The lubricating oil separated from the blow-by gas in the main tappet chamber is stored in the sub-tapppet chamber, and this lubricating oil is introduced into the clearance between the tappet housed in the sub-tappet chamber and the valve stems of the intake and exhaust valves to provide lubrication. The damper effect of oil can sufficiently reduce the impact noise between the tappet and the valve stem of the intake and exhaust valves.
Since the accuracy of the clearance with the exhaust valve may be low to some extent, there is an effect that manufacturing and assembling these parts is facilitated.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II--II in FIG. 1... Crank case, 2... Crank chamber, 3...
・Cylinder liner, 4... Piston, 5... Camshaft, 6... Intake cam, 7... Tappet, 8... Upper wall, 9... Intake valve, 10... Valve stem , 11・
... Valve spring, 12 ... Main tappet chamber, 13
... Gas vent passage, 14 ... Partition wall, 15 ... Sub tappet chamber, 16 ... Communication path, 17 ... Valve stem of exhaust valve, 18 ... Upper wall of main tappet room, 19 ...
Subling retainer, 20... Retainer lock, 21
... Breather plate, 22 ... Tappet chamber cover, 23
... Bolt, 24 ... Discharge port, 25 ... Reed valve, 26 ... Oil shield plate, 27 ... Blowby gas discharge passage.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine that opens and closes intake and exhaust valves via tappets by rotation of a camshaft, a sub-tappet chamber is formed below the main tappet chamber, which communicates with the crank chamber side through a gas vent passage. The contact portion between the tappet and the valve stem of the intake and exhaust valve is housed in the tappet chamber, the main tappet chamber is communicated with the blow-by gas discharge passage, and the lubricating oil separated in the main tappet chamber from the blow-by gas is stored in the sub-tappet chamber. A tappet noise reduction device for an internal combustion engine, characterized in that tappet noise is stored.