JPS59226214A - Intake and exhaust valves of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a valve seat from blow by a structure wherein seat material with higher corrosion resistance than valve base material is equipped over the outer peripheral side of the valve seat and at the same time seat material with higher hardness than valve base material over the inner peripheral side. CONSTITUTION:Corrosion-resisting material 14 containing Ni base material, which is higher corrosion-resistant that valve base material 12, as a base is equipped over the whole outer peripheral surface of a valve. In addition, very hard material 15 containing Co base material, the hardness of which is higher than that of the valve base material 12, as a base is equipped over the whole inner peripheral surface of a valve seat 13 along the periphery of a valve head. Thus, the outer peripheral surface of the valve, which is exposed to high temperature and corrosive gas due to the burning of power quality oil, is made to be hard to the high temperature corrosion. Further, the application of the very hard material at the inner peripheral surface, on which the severe fixing by pressure is applied, makes the formation of indentation difficult. Accordingly, the blow by through the valve seat can be prevented.

Description

[Detailed description of the invention] The present invention relates to intake and exhaust valves for internal combustion engines.

FIG. 1 is a sectional view showing the main parts of a conventional exhaust valve for an internal combustion engine. In the figure, exhaust valve a is at high temperature.

It is exposed to high-pressure combustion gas or exhaust gas, and is in a high-temperature, highly corrosive environment, and its seat portion 3 frequently comes into contact with and separates from the seat portion 7 of the exhaust valve seat, making it susceptible to wear. Therefore, the seat portion 3 of the exhaust valve a is generally required to be made of a material with corrosion resistance and wear resistance.
A sheet member 4 made of a material harder than the material of the valve base material constituting the umbrella portion 2 is welded overlay.

By the way, in the exhaust valve of an internal combustion engine, the sheet member 4 is heated by combustion gas or exhaust gas and becomes high temperature during high load operation of the two engines. In particular, sulfur content, sodium content,
When inferior fuel oil with a high concentration of panadium is burned, corrosion caused by these components at high temperatures may occur and damage the exhaust valve seat.

High-temperature corrosion of the exhaust valve seat gradually progresses in the outer circumferential portion directly exposed to combustion gas and spreads to the inner circumferential surface of the low-temperature section, causing blow-through and impairing the airtightness of the valve.

Therefore, in the conventional exhaust valve a, a material with higher corrosion resistance than the valve base material is used as the seat member 4, and cooling water is passed through the cooling holes 6 provided in the exhaust valve seat. The temperature of the seat member 4 of the exhaust valve a is reduced via the seat portion 7.

This is to prevent the corrosion resistance from deteriorating.

However, the temperature of the seat member 4 increases due to heat conduction from the valve head portion 2, which is affected by the high temperature of the combustion gas over a wide range. In particular, as has been the case recently, when the sulfur, sodium, and vanadium content of fuel oil increases due to the deterioration of fuel oil quality, high-temperature corrosion progresses.

On the seat surface 4' of the sheet member 4, blow-through of the seat portion is likely to occur, and measures to prevent this are required.

Intake valves, which are affected by combustion gases, require the same countermeasures as exhaust valves.

The present invention is intended to solve the above-mentioned problems in conventional intake and exhaust valves for internal combustion engines.

In general, when emphasis is placed on hardness, materials with insufficient corrosion resistance are selected as valve seat materials (e.g., Co-based materials), and when emphasis is placed on corrosion resistance, materials with insufficient hardness (e.g., Ni) are selected.
There is no material that has both excellent properties.

In this case, depending on the nature of each weak point in the sheet material, if the sheet material lacks corrosion resistance, the sheet portion will blow through due to high-temperature corrosion. If the hardness is insufficient, there will be many impressions of combustion residue, and the temperature of the entire valve will rise due to the insufficient seat area, which will also cause blow-through of the valve seat.

The present invention prevents the valve seat portion from blowing through by combining both materials.

The structure of the intake/exhaust valve of the present invention is such that a first seat member having higher corrosion resistance than the valve base material such as Ni-based alloy is attached to the outer circumferential side of the seat part of the valve, and 1st
A second seat member, which is harder than the valve base material such as a Co-based alloy, is attached to the inner circumferential side of the seat member.

Generally, an exhaust valve is assembled so that its inner peripheral surface is seated on the valve seat when the engine is cold. When the engine is running, the valve head becomes hot and the outer circumferential surface of the valve expands.

It will hit the entire sheet.

Therefore, when inferior fuel oil is burned, the outer peripheral surface of the valve is exposed to high-temperature corrosive gas, and high-temperature corrosion is likely to occur. Therefore, if a material with high corrosion resistance is used for this part, durability will be significantly increased. Furthermore, since the inner circumferential surface of the valve is always in a sheet and is less likely to be exposed to high-temperature gas, a highly hard material that is less susceptible to impressions is used.

Embodiments according to the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing the main parts of the exhaust valve of the first embodiment according to the present invention.

In the figure, reference numeral 12 denotes the head portion of the exhaust valve. 13
is a surrounding seat portion, 14 is a corrosion-resistant material based on an N1 base material (for example, Ni-Cr alloy) that has higher corrosion resistance than the valve base material 12, which is attached over the entire outer peripheral surface of the valve;
This is the first sheet member.

Reference numeral 15 indicates a Co base material base (for example, (t
f, made of high hardness material (Cc)-Cr-W alloy), second
This is a sheet member.

The functions and effects of the above configuration will be described.

With the above structure, the exhaust valve, which is exposed to high humidity and corrosive gas due to the combustion of poor quality oil, is exposed to the outer peripheral surface of the exhaust valve.

On the inner surface, which is resistant to high temperature corrosion and has strong pressure bonding,
Since a high hardness material is used, it is difficult to make two impressions.

Therefore, the exhaust valve seat cannot be blown through.

FIG. 3 is a sectional view showing essential parts of an exhaust valve according to a second embodiment of the present invention.

In this case, the corrosion-resistant material 14 is used up to the outer peripheral surface of the valve umbrella.

FIG. 4 is a sectional view showing essential parts of an exhaust valve according to a third embodiment of the present invention.

In this case, the entire valve head contacting surface and the outer circumferential surface of the valve seat are made of a corrosion-resistant material 14.

The functions and effects of both of the above embodiments are the same as those of the first embodiment.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a conventional exhaust valve, FIG. 2 is a sectional view showing the main parts of an exhaust valve according to the first embodiment of the present invention, and FIG. 3 is a sectional view showing the main parts of the exhaust valve according to the first embodiment of the present invention. FIG. 4 is a sectional view showing the main parts of an exhaust valve according to a third embodiment of the present invention. 12... Valve base material, 13... Seat part, 14...
Corrosion resistant material, 15...High hardness material. Fang 1 figure 2 figure 3 square

Claims (1)

[Claims] 1. A first seat member having higher corrosion resistance than the valve base material such as Nt-based alloy is attached to the outer circumferential side of the valve seat portion, and a first seat member having higher corrosion resistance than the first seat member of the valve seat portion is attached to the inner circumferential side of the valve seat portion. An intake/exhaust valve for an internal combustion engine, characterized in that a second seat member having a high hardness is attached to the valve base material such as a Co-based alloy.