JPS60122207A - Exhaust section structure for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent occurrence and developing of crack or recess in seat face by employing laminated structure of high and low hardness layers for the seat face of exhaust valve and valve seat while appearing the annular end face of each layer alternatively from the seat face. CONSTITUTION:The exhaust section of internal-combustion engine is comprised of an exhaust valve and valve seat where the seat face of them is formed with such material as having higher hardness than other portion. Then each seat face such as the seat face 2 of exhaust valve 1 is laminated with low hardness layer 11 composed of such material as having relatively low hardness and high tenacity and high hardness layer 12 having relatively high hardness and low tenacity. Said layers are composed of cobalt system metal or alloy or ceramic. Each layer 11, 12 is made annular continuously around the shaft of valve rod to appear the end face of each layer 11, 12 radially and alternatively from the seat face 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an exhaust structure for an internal combustion engine, and more particularly to an exhaust structure for an internal combustion engine in which the seat surface of a valve or a valve seat is improved.

[Prior Art] A reciprocating internal combustion engine such as a diesel engine is usually provided with an exhaust section consisting of an exhaust valve and a valve seat.

The exhaust valves and valve seats of these internal combustion engines are directly exposed to the high heat of combustion gas, so the IIJ material must be a material that can withstand heat well and does not oxidize easily. Nutenless steel, especially austenitic stainless steel, is widely used. It is used.

As shown in Figures 1 and 2, the exhaust valve l
A cobalt-based or nickel-based hardening material 3 is usually built up on the sheet surface 2 of the sheet, and as shown in FIG.
A hardening material 6 is also built up on the seat surface 5 of the valve seat 4 in the same manner.

However, when a material with relatively low hardness is used as the hardening material, cracks are unlikely to occur on the sheet surface, but as shown in FIG. However, when these grow and continue, a gas passage 8 is formed on the sheet surface, making it impossible for the combustion gas to penetrate tightly and causing a phenomenon of gas blow-out. In addition, if a relatively hard material is used as the hardening material,
Although recesses are less likely to occur on the sheet surface, the sheet surface becomes brittle and cracks 9 are more likely to occur as shown in Figure ff15.

[Object of the Invention] An object of the present invention is to provide an exhaust section structure for an internal combustion engine that solves the problems of the prior art described above and prevents the occurrence and expansion of dents and cracks on the seat surface. .

[Structure of the Invention] In order to achieve this object, the exhaust part structure of an internal combustion engine of the present invention has a sheet surface having a laminated structure of a high hardness layer and a low hardness layer, and a layer of high hardness and a low hardness layer on the sheet surface. It is constructed so that the end faces of the hardness layer appear alternately in an annular shape, and it consists of an exhaust valve and a valve seat, and the material of the seat surface of the exhaust valve and valve seat has a higher grade than the parts other than the seat surface. In the exhaust structure of an internal combustion engine, which is made of high quality materials, the seat surface of at least one of the exhaust valve and the valve seat is made of a first layer with relatively low hardness and a second layer with relatively high hardness. The gist of this invention is an exhaust part structure for an internal combustion engine, which has a laminated structure and has end faces of each node 1 layer and a second layer appearing alternately in an annular shape on the sheet surface.

[Embodiments of the Invention] Examples of the present invention will be described below with reference to FIG. 6 and FIG. ff17.

6(a) to 6(C) are cross-sectional views of the seat surface portion of the exhaust valve according to the embodiment of the present invention, and FIG.

2 is a sectional view of the seat surface portion of the valve seat.

In FIGS. 6(a) to (C) and FIG. 7, the seat surfaces 2 and 5 of the exhaust valve 1 and the valve seat 4 are covered with a first layer 11 made of a hardened material with relatively low hardness and a hardened material with relatively low hardness. Second layers 12 of highly hardened material are laminated alternately. The first layer 11 is preferably made of a material with relatively low hardness and high toughness, and the second layer 12 is preferably made of a material with relatively high hardness and low toughness. All of these are preferably cobalt-based or nickel-based metals or alloys, or ceramic acids.

It is sufficient that these layers ti and 12 are continuous in an annular shape centered on the axis of the valve stem or valve seat, and that the end surfaces of each layer appear alternately in the radial direction on the seat surface. ) and as shown in Fig. 7, each layer is laminated so as to extend in the direction perpendicular to the center line of the valve stem, Fig. 6 (b) or (C)
As shown in the figure, any of those laminated so as to extend in a direction forming an acute angle (or obtuse angle) to the center line of the valve stem may be used.

Furthermore, the plurality of first layers 11 and second layers 12 need not all be made of the same material, and may be made of different materials depending on the characteristics of the location where they are used.

That is, in FIG. 6(C), ILa, llb, lie
, llf are the first layers made of the same material, and lie and lid are the first layers made of a different material from lla, and 1
It is also possible to use 2a, 12b, 12d, and 12e as second layers made of the same material, 12c as 12, and &4- as second layers made of different materials.

In the exhaust valve and valve seat configured in this way, the layers 12.12a, 12b, .
Even if cracks occur in layer 11., which has relatively low hardness.
lla, llb...! It stops at ・, and cracks do not develop over the entire sheet surface. Furthermore, even if a dent occurs in the relatively low hardness layers 11, lla, llb..., the relatively high hardness layers 12, 12a, 12b...
・Because of this, the concavities do not continue to form a gas passage as shown in FIG. 8, and the blowhole phenomenon does not occur.

[Effects of the Invention] As detailed above, the exhaust structure of the internal combustion engine of the present invention has the following features:
The hardened material constituting the seat surface of the valve or valve seat is made of a laminated structure consisting of a first layer with relatively low hardness and a second layer with relatively high hardness, which prevents cracking of the seat surface. The occurrence of cracks or the formation of four parts is suppressed, and the cracks and the four parts are prevented from expanding.

The exhaust structure of an internal combustion engine according to the present invention has excellent heat resistance and abrasion resistance, and has a long life, making it extremely useful industrially.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional internal combustion engine valve, Fig. 2 is a sectional view thereof, Fig. 3 is a sectional view of a conventional valve seat, and Figs. 4 and 5 are views of the seat surface of a conventional exhaust valve. FIGS. 6 and 7 are enlarged views of a portion of the seat surface showing a defect, and are respectively enlarged cross-sectional views of an example of a valve and a valve seat related to the exhaust structure of an internal combustion engine according to the present invention, taken close to the small seat surface. ■・・・・・・υ [Kigo', 2.5... Seat surface, 3.6... Hardening material, 4... Valve seat,
7... recess, 8... gas passage, 9...
...Crack, 11...First layer, 12...
...Second layer. Agent Patent Attorney Tsuyoshi Shigeno

Claims (1)

[Claims] (1) In the exhaust part structure of an internal combustion engine, which consists of an exhaust valve and a valve seat, and the material of the seat surface of the exhaust valve and the valve seat is made of a material with a higher grade than the parts other than the seat surface, the exhaust valve The seat surface of at least one of the valve seats has a laminated structure of a first layer with relatively low hardness and a second layer with relatively high hardness, and the seat surface has a layer of each node 1 and a second layer with relatively high hardness.
An exhaust part structure for an internal combustion engine, characterized in that the end faces of the layers appear alternately in an annular shape.