JPS6021447Y2 - engine exhaust valve device - Google Patents

Description

[Detailed description of the invention] This invention consists of integrally casting the intake and exhaust block with the engine body from aluminum alloy, and allowing the valve shaft of the exhaust valve to slide freely into the valve shaft through hole drilled in the intake and exhaust block. Regarding the supporting device, the valve guide is omitted and the structure is simplified, but the engine is prevented from seizing the valve stem on the peripheral wall of the valve stem through hole and preventing exhaust gas from leaking from the valve stem through hole. The purpose is to enable smooth operation of the vehicle.

Conventionally, the valve guide was press-fitted into a valve shaft through hole drilled in the intake/exhaust block, which resulted in high costs for manufacturing and assembling the valve guide.

In order to save such costs, the present inventor devised a method in which the valve guide is omitted and the valve shaft of the exhaust valve is directly inserted into the valve shaft through hole formed in the intake and exhaust block.

However, if the valve shaft is simply directly inserted, the valve shaft will be tightened and seize due to large thermal expansion of the aluminum alloy peripheral wall of the valve shaft through hole, making operation impossible.

It is also possible to increase the diameter of the valve stem through hole to prevent seizure, but this would cause a large amount of exhaust gas to leak from the valve stem through hole, making it useless.

The present invention has been further improved by fixing a lid that prevents exhaust gas from leaking into the valve stem through hole to the valve stem of the exhaust valve, facing one end of the valve stem through hole within the exhaust port. It is characterized by:

The present invention will be explained below based on the drawings.

Figure 1 shows a longitudinal side view of a forced air-cooled side valve type engine.
Reference numeral 1 in the figure is the engine body, which is made by integrally forming a crankcase 2 and a cylinder block 4 into which cylinders 3 are cast by aluminum die-casting, and fixing a head block 6 having a combustion chamber 5 to the upper part. It is.

An intake and exhaust block 7 is integrally formed with the engine body above the front of the cylinder block 6, and the cylinder block 4 is connected to the earthen wall of a tappet chamber 8 formed in the upper part of the crankcase 2 by a valve guide block 9. be.

Reference numeral 10 is an exhaust port provided in the intake/exhaust block 7, and a muffler 11 is fixed to the front end.

Further, the valve guide block 9 is provided with a valve shaft through hole 12.

The exhaust valve 13 is connected to the exhaust valve 1 from the upper end 10a of the exhaust port 10.
The valve shaft 13a of No. 3 passes through the valve shaft through hole 12, and the valve shaft 13a passes through the valve shaft through hole 12.
The lower end 13b of the valve shaft 13a is inserted into the tappet chamber 8, and the coiled valve spring 14 is attached to the lower end 13b of the valve shaft 13a, which is then assembled into the engine.

When the valve shaft 13a of the exhaust valve 13 passes through the valve shaft through hole 12, a gap 18 is created between the valve shaft 13a and the valve shaft 13a.

This gap 18 is large enough to absorb the difference in thermal expansion when the valve stem through hole 12 and the valve stem 13a expand in response to engine heat.

The exhaust valve 13 assembled in this manner is moved up and down via the tappet 16 by rotation of the cam 15 to disconnect and disconnect communication between the combustion chamber 5 and the exhaust port 10.

A disc-shaped i19 that covers the upper end 18a of the gap 18 between the valve shaft 13a and the valve shaft through hole 12 when the exhaust valve 13 is seated on the valve seat 17 provided at the upper end lea of the exhaust port 10 is attached to the valve shaft 13a. The cam 15 is fixed to the cam 15 via the tappet 16.
When the exhaust valve 13 is suddenly pushed up, the lower part of the lid 19 becomes negative pressure, and the blow-by gas containing lubricating oil sent to the tappet chamber 8 is pumped into the gap 1 between the valve shaft 13a and the valve shaft through hole 12.
8 to lubricate the valve shaft 13a, and the lid 19
The upper surface 19 acts as a shielding plate that prevents exhaust gas sent from the combustion chamber 5 to the exhaust port 10 from entering the gap 18.

What is shown in FIG. 3 shows another embodiment of the lid 19 provided on the valve shaft 13a.
2b is made into a tapered shape, and the peripheral edge 19b of the lid 19 is folded down into a tapered shape so as to fit onto the tapered shape.

In this case, when the exhaust valve is pushed up and the lid is raised, the suction force of the blow-by gas generated in the gap increases.

The engine shown in FIG. 4 is one in which the present invention is applied to an overhead valve type engine in which an intake and exhaust block 7 is mounted and fixed on the upper part of a cylinder block 6.

As mentioned above, in this invention, the diameter of the valve stem through hole is made thicker to form a gap that absorbs the difference in thermal expansion.It is only necessary to fix the lid to the valve stem of the waist exhaust valve, and the valve guide block is omitted. In addition, since the assembly of the valve guide can save time and effort, the engine can be manufactured at low cost.

Moreover, since the lid reliably prevents exhaust gas from leaking through the gap for absorbing thermal expansion difference, the engine can be operated smoothly.

Also, when the exhaust valve opens, the negative pressure generated at the bottom of the lid
Since lubricating oil is sucked into the valve stem through hole, wear of the valve stem and the valve stem through hole is prevented, resulting in excellent durability.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; Fig. 1 is a longitudinal side view of a forced air-cooled side valve type engine; Fig. 2 is an enlarged view of the main parts; Fig. 3;
FIG. 4 is a diagram corresponding to FIG. 2 showing different embodiments. 1...Engine body, 4...Cylinder block, 7...Intake and exhaust block, 10...
...exhaust port, 10a... end of 10, 1
2...Valve shaft through hole, 12a...Outer peripheral wall of 12, 12b...Outer peripheral surface of 12a, 13...
...exhaust valve, 13a...13 valve stem, 17
...Valve seat, 1t...Gap for absorbing thermal expansion difference, 18a...End face of 18, 19...
Lid, 19a...periphery of 19.

Claims (1)

[Claims for Utility Model Registration] 1. The engine body 1 and the intake/exhaust block 7 are integrally cast from aluminum alloy, and a valve dust catcher 17 is formed on the circumferential surface of the starting end 10a of the exhaust port 10 of the intake/exhaust block 7. With,
A valve shaft through hole 12 is formed in the wall of the base, and the valve shaft through hole 1
2, insert the valve shaft 13a of the exhaust valve 13 from the port starting end 10a side, leave a sufficiently large gap 18 for absorbing thermal expansion difference between the valve shaft 13a and the valve shaft through hole 12, and insert the valve shaft 13a in the exhaust port 10. A lid 19 having a larger diameter than the valve shaft through hole 12 is fixed to the shaft 13a, and when the exhaust valve 13 is in contact with the valve dust catcher 17 and closed, the lid 19 connects the valve shaft through hole 12 to the exhaust port side. An exhaust valve device for an engine, characterized in that it is configured to be covered from above. 2. The exhaust valve device for an engine according to claim 1, wherein the engine body 1 is a cylinder block 4 of a side valve type engine. 3. The exhaust valve device for an engine according to claim 1, wherein the engine body 1 is a cylinder block 4 of an overhead valve type engine. 4. The exhaust valve device for an engine as set forth in claim 1, 2, or 3 of the utility model registration claim, in which the lid 19 is formed into a flat brim shape. 5 Form the outer peripheral surface 12b of the upper peripheral wall 12a of the valve shaft through hole 12 into a tapered shape, and fold down the peripheral edge 1sb of the lid 19 into a tapered shape to form the tapered outer peripheral surface 1 of the valve shaft through hole 12.
Claims 1 and 2 for utility model registration that are incorporated into 2b.
Exhaust valve device for the engine described in item 3 or item 3.