JP3381214B2 - Valve seat for internal combustion engine and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat with which a valve face of an engine valve in an internal combustion engine abuts, and more particularly to a valve seat having excellent wear resistance and a manufacturing method thereof.

[0002]

2. Description of the Related Art As shown in FIG. 6, a valve seat (01)
Is attached to the open end of the port (03) formed in the cylinder head (02). The valve seat (01) has an annular shape with a substantially rectangular cross section, and the engine valve (0
The conical seat surface (0) where the valve face (05) of 4) closely contacts
6) has been formed.

The valve face (05) of the engine valve (04), which vertically moves in the axial direction during engine operation, repeatedly abuts the seat surface (06) of the valve seat (01) to seal the cylinder. Therefore, high adhesion and wear resistance are required.

In order to meet this requirement, the conventional valve seat has a raw material powder and hard particles (or solid lubricant) as a material.
Are mixed by stirring in advance, and then a green compact is formed by compression molding, and this is sintered so that the material of the dough and the hard particles are uniformly dispersed in the structure. .

[0005]

In the above-mentioned prior art, since the specific gravity and particle size differ depending on the type of powder particles to be blended, it is possible to obtain a completely uniform dispersion state even if stirring and mixing are sufficiently carried out. Is difficult, and some segregation is unavoidable.

Therefore, the distribution of the fabric material and the hard material in the structure of the valve seat after molding becomes non-uniform, and a region having a high ratio of hard particles or a region having a low ratio of hard particles is generated, and the valve seat (01) seat is formed. The surface (06) is unevenly worn, the wear resistance is reduced, and the life is shortened.

If a hard material such as stellite is adhered to the entire surface of the sheet (06) by overlaying in order to improve wear resistance, the layer of the hard material is relatively brittle, so that peeling or cracking is likely to occur. On the contrary, the durability may decrease.

The present invention has been made in order to solve the above problems, and the sheet surface has a structure in which soft regions and hard regions are uniformly arranged, so that the adhesion and wear resistance are remarkably improved. An object of the present invention is to provide a valve seat that can be improved and a manufacturing method thereof.

[0009]

According to the present invention, the above problems can be solved as follows. (1) In a valve seat mounted on a cylinder head of an internal combustion engine and having a seat surface with which a valve face of an engine valve abuts on an inner peripheral edge, the seat surface is
A large number of regions of the soft layer and regions of the hard layer are alternately arranged in the circumferential direction, with the areas of both regions being the required ratios.

(2) In the above item (1), each soft layer region and each hard layer region are formed radially.

The valve seat is formed by compressing powder of a soft metal material to form a green compact made of an annular soft layer having a seat surface at an inner peripheral edge thereof, and a large number of slits are formed on the seat surface. Consisting of the soft layer, a step of radially opening the uniform through holes at substantially equal intervals, a step of filling each of the slit through holes with a powder of a hard metal material and compressing it to form a hard layer, and the soft layer. It is manufactured by a sintering process in which a green compact and a hard layer filled in each slit-shaped through hole are sintered and integrally bonded.

[0012]

In the seat surface of the valve seat with which the valve face of the engine valve abuts, the areas of the soft layer and the areas of the hard layer are alternately arranged in the circumferential direction at a required surface contact ratio, so that the conventional structure is achieved. Segregation of various structures can be prevented, and adhesion and wear resistance to the valve face of the engine valve can be improved.

[0013]

1 is a partially cutaway perspective view showing a valve seat according to an embodiment of the present invention.

The valve seat (10) is a ring of soft material.
(Hereinafter, referred to as a soft torus) (11) and an annular body of a hard material (hereinafter referred to as a hard torus) (12) form a two-layer structure by stacking in the axial direction, and as a whole, desired Is formed in the shape of the valve seat. The soft material is, for example, Fe-Ni-Cr-Mo-C-based Fe-based material, and the hard material is Co-Mo-Cr-Si-based Co-based material, that is, stellite or triballoy. Are suitable.

At the inner periphery of the upper edge of the soft torus (11) is a conical seat surface that is aligned with the valve face of the engine valve.
(13) is formed. Further, the soft annular body (11) has a large number of slit-shaped through holes (1
4) is bored in the axial direction. The through holes (14) are arranged radially with respect to the center of the valve seat (10) and at substantially equal angles and intervals in the circumferential direction.

On the upper surface of the lower hard annular body (12), a large number of protrusions (15) aligned with the through holes (14) of the soft annular body (11) are provided so as to project upward, and (15) is tightly fitted in the through hole (14). The upper end of each protrusion (15) is attached to the seat surface (1
It is formed as a tapered surface that is flush with 3).

With this structure, the seat surface (13) has a region of the soft layer (11a) made of the soft material of the soft torus (11) and a hard torus (12). The regions of the hard layer (12a) formed of the hard material are alternately arranged radially.

Therefore, the segregation of the structure as in the conventional valve seat formed by mixing the soft material and the hard material in advance is eliminated, and the valve seat is excellent in the adhesion and wear resistance to the valve face of the engine valve. be able to.

Further, by changing the opening area of each through hole (14) with respect to the total area of the seat surface (13), the seat surface (1
The area ratio between the region of the soft layer (11a) and the region of the hard layer (12a) in 3) can be set to a required value, and therefore, the application of the engine or the material of the engine valve or the soft material and the hard material. By appropriately adjusting the area ratio of both regions according to the composition and the like, it becomes possible to easily obtain a valve seat having arbitrary characteristics.

Further, since the region of the hard layer (12a) made of a relatively brittle material is sandwiched by the soft material of the cloth, the hard layer (1
The desired durability can be maintained without peeling or damage of 2a).

2 to 5 are cross-sectional views schematically showing a step of molding a green compact for manufacturing the valve seat of the present invention, and showing the operation of the compression molding machine in the order of steps.

This compression molding machine is composed of two upper and lower groups of punch devices. The lower punch group has a die (21) having a circular hole (21a) having a diameter corresponding to the outer diameter of the valve seat.
, And is arranged concentrically in the die (21), and is installed between the cylindrical lower core rod (22) having a diameter corresponding to the inner diameter of the valve seat, and the die (21) and the lower core rod (22), An annular lower first punch (23) having a tapered surface (23a) corresponding to the seat surface (13) of the valve seat shown in FIG.
And a soft annular body of the valve seat, which is vertically movably fitted in the fitting groove (23b) of the lower first punch (23).
Comb-shaped upward protrusions (2) corresponding to the slit-shaped through holes (14) of (11).
4a) and a lower second punch (24). The upper end of the upward protruding piece (24a) is a tapered surface (24b) having the same angle as the seat surface (13).

The upper punch group has an upper core rod (25) having the same diameter as the lower core rod (22) and coaxially installed, and a lower first punch (23) slidably fitted to the outer periphery thereof. An annular upper first punch (26) having the same diameter as that of the upper first punch (2
The upper second punch fitted in the fitting groove (26a) of 6) so as to be movable up and down.

The core rod (25) of the upper punch group, the first,
The second punches (26) and (27) are configured to be movable relative to each other in the axial direction, so that the three punches can be moved integrally or individually.

In the first step of FIG. 2, the upper punch group is raised, the lower first punch (23) is lowered, and the lower second punch (24) is further attached to the die (21) and the lower core rod (22). ) Projected above the upper end surface.

The gap formed by the die (21) and the lower core rod (22) is filled with the powder of the soft material (S) forming the soft torus (11).

Then, in the second step of FIG. 3, only the upper first punch 26 is lowered to compress the powder of the soft material (S). By this process, a plurality of lower second punches (2
A soft torus with through holes (14) formed at positions corresponding to (4)
A green compact (11 ') having almost the same shape as (11) is molded.

In the third step of FIG. 4, the upper punch group is lifted to be separated from the lower punch group, and the lower second punch (24) is moved to the tapered surface (23a) of the lower first punch (23).
Down to below. The upper part of the green compact (11 ') made of the soft material (S) formed by the previous step and the second lower punch (2
Hard material is placed in the through hole group opened by descending of 4).
Fill with powder of (H).

Then, in the fourth step of FIG. 5, the upper first punch (26) and the upper second punch (27) are lowered as a unit, and at the same time, the lower second punch (24) is moved to its tapered surface.
(24b) is moved up to a position where it is aligned with the tapered surface (23a) of the lower first punch (23) to compress the hard material (H),
A green compact (12 ') having almost the same shape as (12) is formed.

As a result, the green compact (1) made of the soft material (S)
1 ') and a green compact (12') made of a hard material (H) are integrally formed into a two-layer green compact, and if this is sintered, the valve seat (10) ( Is shown upside down).

The present invention has been described above based on the illustrated embodiments, but the present invention is not limited to the above-mentioned contents and includes various modified applications.

For example, by reversing the relationship between the soft material and the hard material in the embodiment, the sheet surface having the through holes (14) opened.
The upper torus (11) having (13) may be formed of a hard material, and the lower torus (12) may be formed of a soft material.

Alternatively, the entire valve seat (10) may be formed of a soft material, and a hard material may be fitted into the comb-shaped through hole (14) opened in the seat surface (13). Such valve seats are
In the process shown in FIG. 4, the green compact (1
It can be easily manufactured by filling the upper part of 1 ') with the soft material (S) again instead of the hard material and compressing it with the upper first punch (26). In the above embodiment, the slit-shaped through holes
Although (14) is provided in the radial direction, it may be provided in an oblique direction with a certain angle in the radial direction.

[0034]

【The invention's effect】

(a) Since the seat surface of the valve seat with which the valve face abuts is formed by the region of the soft layer and the region of the hard layer, it is unavoidable in the conventional method of mixing different material powders by stirring and mixing in advance. The problem of segregation of the existing structure can be solved, the adhesion to the valve face and the wear resistance can be remarkably improved, and a valve seat excellent in durability can be obtained.

(B) Since the region of the hard layer, which is relatively brittle, is held by the soft layer, the hard layer is not peeled or damaged, and the durability is improved.

(C) According to the method of the present invention, the region of the soft layer and the region of the hard layer on the sheet surface can be easily formed, and the opening area ratio of each slit-shaped through hole to the entire sheet surface. By appropriately adjusting the, it is possible to easily set the area ratio between the soft layer region and the hard layer region to an arbitrary value according to the composition of the soft material and the hard material and the characteristics required for the valve seat. You can

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a valve seat of the present invention.

FIG. 2 is an explanatory view showing a first step of manufacturing the valve seat of the present invention.

FIG. 3 is an explanatory view showing a second step of the same.

FIG. 4 is likewise an explanatory view showing a third step.

FIG. 5 is an explanatory diagram similarly showing a fourth step.

FIG. 6 is a vertical cross-sectional view showing a valve seat and an engine valve to which the present invention is applied.

[Explanation of symbols]

(10) Valve seat (11) Soft torus (11a) Soft layer (11 ') (12') green compact (12) Hard torus (12a) hard layer (13) Seat surface (14) Slit-shaped through hole (15) Protrusion (21) Die (22) Lower core rod (23) Lower first punch (23a) Tapered surface (23b) Mating groove (24) Lower second punch (24a) Upward protrusion (24b) Tapered surface (25) Upper core rod (26) Upper first punch (26a) Mating groove (27) Upper second punch (S) Soft material (H) Hard material

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01L 3/02

Claims (3)

(57) [Claims] 1. Attached to a cylinder head of an internal combustion engine,
Further, in a valve seat having a seat surface on which the valve face of the engine valve abuts on the inner peripheral edge, a large number of soft layer regions and hard layer regions are provided on the seat surface, and the area of both regions is set as a required ratio. A valve seat for an internal combustion engine, which is arranged alternately in the circumferential direction. 2. A region of each soft layer and a region of each hard layer are defined by
The valve seat for an internal combustion engine according to claim 1, wherein the valve seat is formed radially. 3. A soft metal material powder is compressed to form a green compact made of an annular soft layer having a sheet surface at the inner peripheral edge thereof, and a large number of slit-shaped through holes are formed on the sheet surface. A radial opening at substantially equal intervals; a step of filling each slit-shaped through hole with a powder of a hard metal material and compressing it to form a hard layer; and a green compact made of the soft layer. And a sintering step in which the hard layer filled in each slit-like through hole is sintered and integrally bonded, and a method of manufacturing a valve seat of an internal combustion engine.