KR20190028804A - Valve seat with excellent durability - Google Patents

Abstract

A valve seat excellent in durability is provided. A valve seat which is press-fitted into a cylinder head made of a light metal alloy of an internal combustion engine and has a convex portion having a mountain height or a valley depth of 5 to 80 占 퐉 and / or a valley depth of 5 占 퐉 to 100 占 퐉 And a total area ratio of not less than 0.3%. In place of the above-mentioned roughened area, the roughened area may be formed by a concavo-convex mixing part having concavities and convexities formed by adjoining concave parts and convex parts extending in the press-in direction, in a direction perpendicular to the press- Concave portions extending in the direction of the circumferential direction and convex portions formed adjacent to the convex portions may be a region made up of concave-convex mixing portions having a plurality of rows in the direction perpendicular to the circumferential direction. The concavo-convex mixing portion may be a concavo-convex mixing portion in which the concave portions are arranged in a lattice form. As a result, the high temperature holding force of the valve seat is increased, and the dropout load is increased, thereby preventing the valve seat from being disengaged during operation. It is preferable that the roughed area is formed by laser light irradiation.

Description

Valve seat with excellent durability

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat for an internal combustion engine, and particularly relates to improvement of durability of a valve seat which is press-fitted into a cylinder head made of a light metal alloy.

The valve seat plays a role of cooling the seal of the combustion gas and the valve, and has been used by being press-fitted into the cylinder head of the engine. However, the press-fitted valve seat is not actually in contact with all the surfaces of the cylinder head, but the retaining force at high temperature (hereinafter also referred to as a high-temperature holding force) is insufficient during engine operation and may be lost.

Regarding such a problem, for example, Patent Document 1 proposes a valve seat fall prevention structure. The valve seat slip prevention structure disclosed in Patent Document 1 is characterized in that an annular groove is formed on the inner circumferential surface of the cylinder head press-fit bore and an annular groove is formed on the outer circumferential surface of the valve seat press- And an extension ring extending in the radial direction is inserted into the space formed in the annular grooves. According to this, when the valve seat is mounted on the cylinder head, the compressed expansion ring is expanded when it enters the annular groove formed on the inner peripheral surface of the press-fit hole and the annular groove formed on the outer peripheral surface of the valve seat after the valve seat is press- So that the movement of the valve seat in the axial direction is completely restrained, and dropout can be reliably prevented.

Japanese Utility Model Publication No. 01-83109

However, according to the technique described in Patent Document 1, it is necessary to form the annular groove by performing grooving on the inner circumferential surface of the press-fit hole and the outer circumferential surface of the valve seat of the cylinder head, complicating the manufacturing process, There is a problem that it is difficult to secure the machining accuracy of the machining tool. In addition, in the technique described in Patent Document 1, there is also a problem that the expansion ring is shaken off due to vibration at the time of press-fitting, and that it is difficult to secure a desired function.

An object of the present invention is to provide a valve seat which is used by being pressed into a cylinder head made of a light metal alloy of an internal combustion engine to overcome the problems of the prior art and to provide a valve seat excellent in durability that does not easily fall off during operation of the internal combustion engine .

In order to achieve the above object, the inventors of the present invention have extensively studied various factors affecting the durability of a valve seat which is press-fitted into a cylinder head made of a light metal alloy of an internal combustion engine.

As a result, the press-fitted valve seat is not in full contact with the cylinder head, so that there arises a problem that the retaining force (retaining force at high temperature) is lost during operation of the internal combustion engine. In order to improve the holding force (holding force at a high temperature) and to avoid the occurrence of such a problem, the present inventors have conceived that the outer circumferential surface of the valve seat contacting the inner circumferential surface of the cylinder head is roughened.

The outer circumferential surface of the valve seat is usually finished to an arithmetic average height (Ra) defined by JIS B 0601-2001 of about 0.8 mu m. When the valve seat is press-fitted into a cylinder head made of a light metal alloy, the inventors of the present invention roughly make the surface of the outer circumferential surface of the valve seat coarser than the normal finishing surface, , The " high temperature drop load " which is an index of the high temperature holding force is remarkably increased, and the dropout resistance is improved. Further, it has been found that the area to be roughened does not have to be the entire circumference of the valve seat but is sufficiently effective even in a partial region of the outer circumferential surface of the valve seat.

That is, a region (hereinafter also referred to as " convex portion ") or a maximum valley depth (or valley depth) in which the maximum peak height (or peak height) It has been found that provision of at least one region (hereinafter also referred to as a concave portion) having a thickness of 5 to 100 탆 contributes significantly to the improvement of the durability of the valve seat. If the area having the maximum peak height (or the peak height) or the area having the maximum peak depth (or depth) is present in an area ratio of 0.3% with respect to the entire outer peripheral surface, I also found that it worked well enough.

The present invention has been further completed based on such findings, and further completed. That is, the gist of the present invention is as follows.

(1) A valve seat which is press-fitted into a cylinder head made of a light metal alloy of an internal combustion engine, characterized in that the valve seat is formed as a rough surface region at least at one position on the outer circumferential surface of the valve seat, , And / or a concave portion having a depth of 5 占 퐉 to 100 占 퐉, wherein the roughened region is an area ratio with respect to the entire outer peripheral surface, and is 0.3% or more in total Excellent valve seat.

(2) In the above-mentioned (1), the convex portion may be formed in such a manner that the mountain height of the convex portion continuously or stepwise increases from the reference to the maximum mountain height along the press- Wherein the valve seat is a region having a valve seat.

(3) The golf club head according to (1), wherein the concave portion has a tapered valley depth, which is continuously or stepwise decreased from a maximum valley depth to the reference along the press-in direction with respect to the outer circumferential surface, Wherein the valve seat is a region having a valve seat.

(4) In the above-mentioned (1), it is preferable that the roughened region includes a concave-convex mixing portion having concavities and convexes adjoining the convex portions extending in the press-fit direction and having a plurality of rows in a direction perpendicular to the press- And concave and convex portions extending in the circumferential direction and having a plurality of rows in a direction perpendicular to the circumferential direction.

(5) In the item (4), it is preferable that the direction in which the concave portion and the convex portion extend in the concave-convex mixing portion is a direction having an angle in the range of more than 0 DEG and less than 90 DEG Features valve seat.

(6) In (4), as the roughened region, a lattice-shaped concave portion formed by combining a plurality of rows of concave portions extending in a certain direction of the concave-convex mixing portion and a plurality of rows of concave portions extending in a direction perpendicular to the predetermined direction And the concavities and convexities having convex portions in the respective lattice of the latticed concave portions.

(7) The production method according to any one of (4) to (6), wherein the convex portion is a convex portion having a mountain height of 5 占 퐉 to 80 占 퐉 with respect to the outer circumferential surface, And the valley depth is 5 占 퐉 to 100 占 퐉.

(8) The method according to any one of (4) to (7), wherein the concavo-convex mixing portion has irregularities having a pitch of 1 占 퐉 to 600 占 퐉 which is a distance between two adjacent convex portions in a cross section perpendicular to the extending direction Wherein the valve seat is provided with a valve seat.

(9) The apparatus according to any one of (4) to (8), characterized in that a mountain height of convex portions in a plurality of rows of the concavo-convex mixing portion is a constant height with respect to the outer circumferential surface or increases along the press- .

(10) The method according to any one of (1) to (9), wherein the roughened region is observed in a direction perpendicular to the outer circumferential surface to form a triangular shape, a square shape, a circular shape, a semicircular shape, Of the valve seat.

(11) In (10), it is preferable that the roughened region is formed only on the periphery of any one of the triangular shape, the rectangular shape, the circular shape, the semicircular shape, and the star shape, Wherein the valve seat is formed into a shape.

(12) The valve seat according to any one of (1) to (11), wherein the rough surface region is formed at an angular position in the circumferential direction at regular intervals.

(13) A valve seat according to any one of (1) to (12), wherein the valve seat is a iron-base sintered alloy.

According to the present invention, the high-temperature holding force of the valve seat press-fitted into the cylinder head made of a light metal alloy of the internal combustion engine is increased, and the occurrence of such problems that the valve seat is released during operation of the internal combustion engine is remarkably reduced. do.

Fig. 1 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 2 is a cross-sectional view schematically showing the outline of the high-temperature holding force measuring device.
3 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 4 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 5 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 6 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 7 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 8 is an explanatory view schematically showing a preferable shape of the roughed area.
Fig. 9 is an explanatory view schematically showing a preferable shape of the roughed area.
10 is an explanatory view schematically showing a preferable shape of the roughed area.

The valve seat of the present invention is used in a state where it is press-fitted into a cylinder head made of a light metal alloy such as an aluminum alloy or a magnesium alloy of an internal combustion engine. The valve seat of the present invention is formed such that the material is processed to a predetermined dimension and a "roughened region" is formed at least at one portion of the outer circumferential surface of the valve seat. The term " roughened area " as used herein refers to a region of a rough surface property and a state of locally rough surface, as compared with the surface roughness (Ra: about 0.8 탆) of a normal finished surface. This "roughened surface area" is a surface area of a cylinder head made of a light metal alloy, which is engaged with a surface layer of a cylinder head made of a light metal alloy when the valve seat is press-fitted into the cylinder head made of a light metal alloy, Thereby contributing to an increase in the unloading load and suppressing the disengagement of the valve seat during engine operation.

The " roughened area " refers to a convex part having a mountain height of 5 占 퐉 to 80 占 퐉 at a predetermined height and / or a concave part having a depth of 5 占 퐉 to 100 占 퐉 desirable.

If the mountain height of the convex portion is less than 5 占 퐉, the mountain height is too low to prevent the valve seat from coming off. On the other hand, when the mountain height exceeds 80 mu m, the light metal alloy such as the aluminum alloy of the cylinder head is removed, and the adhesion with the cylinder head is lowered due to the light metal alloy such as the aluminum alloy. Therefore, the peak height of the convex portion is limited to the range of 5 탆 to 80 탆. The height of the acid is preferably 10 占 퐉 to 40 占 퐉, more preferably 20 占 퐉 to 35 占 퐉.

If the valley depth of the recessed portion is less than 5 占 퐉, the valley depth is too shallow to insufficiently engage the light metal alloy such as aluminum alloy of the cylinder head, so that the valve seat can not be detached. On the other hand, when the trough depth exceeds 100 mu m, the light metal alloy such as aluminum alloy of the cylinder head is removed and the adhesion with the cylinder head is lowered accordingly. Therefore, it is preferable to limit the valley depth of the concave portion (" roughened region ") to a range of 5 mu m to 100 mu m. The depth of the trough is preferably 10 탆 to 100 탆, more preferably 15 탆 to 35 탆.

In the present invention, a convex portion or a concave portion having such a surface property and a state may be formed over the entire outer circumferential surface as the " roughened region ", but it is preferable that at least one portion of the outer circumferential surface has a total area ratio 0.3 %, It is possible to sufficiently maintain the desired holding force. Therefore, the total area of the " rough surface area " including the convex portion and / or the concave portion is 0.3% or more in terms of the area ratio with respect to the entire circumferential surface. Further, it is preferably 0.5% or more. On the other hand, if the roughened area exceeds 50% as a total area ratio, the increase in the holding force of the press-fitted valve seat is saturated. Therefore, it is preferable to limit the total area ratio to 0.5% or more and 50% or less with respect to the entire circumferential surface area. The convex portion having the above-described surface properties and conditions may be formed over the entire circumferential surface by a shot-blast process, a sand-blast process, or the like.

The shape of the " roughened region ", which is the convex portion or the concave portion, is not particularly limited, but it is preferable that the shape becomes a region that is long in a direction orthogonal to the press-in direction from the viewpoint of improvement in durability. By providing a shape that becomes a long region in a direction orthogonal to the press-in direction, the resistance at the time of leaving becomes large, so that the lost load is increased and the durability is improved. For example, as schematically shown in Figs. 1 (a) and 1 (b), it is preferable to observe in a direction perpendicular to the outer peripheral surface to form a shape showing an inverted triangular shape or a quadrangular shape in the press-in direction . Further, there is no problem even if it is a shape showing a triangular shape, a circular shape, a semicircular shape, or a star shape. Fig. 5 shows an example of a semicircular shape, and Fig. 6 shows an example of a star shape.

The shape of the "roughened area" is obtained by machining the entire area of the reverse oval shape and the rectangular shape as shown in FIG. 1 (a) and FIG. 1 (b) Or may be an area obtained by roughening only a predetermined width of the periphery (outline) of the above-described shape as schematically shown in Figs. 1C and 1D.

Further, in the present invention, the " convex portion " as the " roughened region " has a maximum mountain height Or may be a region having a tilted mountain height continuously or stepwise increasing from the tilted mountain height. As shown in Fig. 4B, the " concave portion " is formed in such a manner that the valley depth is inclined with respect to the outer circumferential surface continuously or stepwise from the maximum valley depth to the reference along the press- It may be a region having a trough depth. By forming the region having such a tilted mountain height and valley depth, the valve seat can be easily press-fitted.

In the present invention, the " roughened region " is defined as a region having a plurality of rows of concavities and convexities formed by adjoining concave portions and convex portions extending in the press-in direction in a direction perpendicular to the press-in direction, The adjacent irregularities may have a plurality of rows in the direction perpendicular to the circumferential direction. These areas may be used alone or in a mixture thereof to form a " roughened area ". In the present invention, such a region is referred to as " concavo-convex mixing portion ". By providing such an area on the outer circumferential surface of the valve seat, the durability is improved as compared with the case where the convex portion and / or the concave portion is disposed. An example of the " concave-convex mixing portion " as the roughened region is shown in Figs. 7 and 8. Fig.

The direction in which the concave portion and the convex portion extend extends in the press-in direction or in the circumferential direction, but the extending direction is a direction (oblique direction) having an angle in the range of more than 0 DEG and less than 90 DEG It is also good. The same effect as described above can be expected even in such a roughed area.

The concavo-convex mixing portion has a lattice-like concave portion formed by combining a plurality of concave portions extending in a predetermined direction and a plurality of concave portions extending in a direction perpendicular to the predetermined direction, The concavo-convex mixing portion may be a concavo-convex mixing portion formed of concavo-convex portions having convex portions in each lattice of the portion. An example of such surface properties and conditions is schematically shown in Fig. In such a concavo-convex mixing portion, the convex portion shows a surface property and a state in which the convex portion sparsely exists in an island shape within the lattice-like concave portion. Incidentally, the term " vertical direction with respect to a certain direction " as used herein includes, in addition to precisely " vertical ", a case of " almost vertical "

In the "concavo-convex mixing portion", it is preferable that the concavo-convex portion is formed of convex portions having a mountain height of 5 μm to 80 μm and concave portions having a groove depth of 5 μm to 100 μm on the outer circumferential surface as a reference. If the mountain height of the convex portion is less than 5 占 퐉, the mountain height is too low to prevent the valve seat from coming off. On the other hand, when the maximum peak height exceeds 80 占 퐉, the light metal alloy such as aluminum alloy of the cylinder head is removed, and the adhesion with the cylinder head is lowered due to the light metal alloy such as the removed aluminum alloy. Therefore, the peak height of the convex portion in the " concavo-convex mixing portion " is limited to the range of 5 to 80 mu m. The peak height is preferably 10 占 퐉 to 50 占 퐉, more preferably 20 占 퐉 to 40 占 퐉.

If the depth of the concave portion is less than 5 占 퐉, the depth of the valley is too shallow to insufficiently engage the aluminum alloy of the cylinder head, thereby preventing the valve seat from coming off. On the other hand, if the trough depth exceeds 100 mu m, the aluminum alloy of the cylinder head is removed, thereby reducing the adhesion with the cylinder head. Therefore, it is preferable to limit the valley depth of the concave portion in the " concave-convex mixing portion " to a range of 5 mu m to 100 mu m. Further, the depth of the bones is preferably 10 탆 to 100 탆, more preferably 15 탆 to 45 탆.

The "concave-convex mixing region" as the "roughening region" is a region in which a pitch (hereinafter also referred to as a mountain pitch) between the adjacent two convex portions in a cross section perpendicular to the direction in which the concave portion and the convex portion extend extends It is preferable that the concavo-convex portion be 600 mu m or less. If the acid pitch of the convex portion is less than 1 占 퐉, the pitch is too narrow to sufficiently engage the aluminum alloy of the cylinder head, and the adhesion with a desired cylinder head can not be ensured. On the other hand, if the acid pitch exceeds 600 mu m, the pitch is too wide to sufficiently engage the aluminum alloy of the cylinder head, so that the adhesion with the desired cylinder head can not be ensured.

In the "concave-convex mixing portion" as the "roughening region", the convex portion may be a convex portion having a constant mountain height with reference to the outer circumferential surface, or a convex portion having a mountain height increasing along the press-in direction.

It is preferable that the shape of the concave-convex mixing portion as the "roughening region" is a shape that becomes a long region in a direction orthogonal to the press-in direction, like the concave or convex portion described above, Do. By providing a shape that becomes a long region in a direction orthogonal to the press-in direction, the resistance at the time of leaving becomes large, so that the lost load is increased and the durability is improved. For example, it is preferable to take a shape that shows either a triangular shape, an inverted triangular shape, a rectangular shape, a circular shape, a semicircular shape, or a star shape in a direction perpendicular to the outer peripheral surface. The shape of the " roughened area " may be a region obtained by roughening the entire surface of the above-described surface with the above-described surface properties and conditions, or by roughening only a predetermined width of the periphery .

As the " roughened area ", the " concave-convex mixing part " having the above-described surface properties and conditions may be formed over the entire circumferential surface. However, at least one portion of the outer circumferential surface forms an area ratio of not less than 0.3% So that a desired holding force can be sufficiently maintained. Therefore, the total area of the " roughened area " consisting of the " concave-convex mixing part " Further, it is preferably 0.5% or more. On the other hand, even if the roughed area exceeds 50% as a total area ratio, the increase in the holding force of the press-fitted valve seat is only saturated. Therefore, the total area ratio to the entire circumferential surface is preferably 0.5% or more and 50% or less.

In the valve seat of the present invention, the "surface roughed area" having various surface properties and states is provided at two positions in the circumferential direction of the valve seat at intervals of at least one position, preferably around the axis of the valve seat, It is preferable to form them at angular positions at regular intervals in the circumferential direction of the valve seat, such as three positions at intervals of 120 DEG around the axis, as shown in Fig. 1 (e).

The "roughened region" of the various surface properties and states is preferably formed by laser light irradiation treatment in the present invention, or shot blast treatment or spraying depending on the surface properties and conditions. When the entire surface of the outer circumferential surface of the valve seat is used as the roughened surface area, it is preferable to use the shot blast treatment from the viewpoints of productivity and economy. However, depending on the surface properties and conditions, Marks) may be used.

In the present invention, the irradiation of the laser beam is carried out in such a manner that the irradiation pattern and the irradiation time are set so as to become the " roughened region " having the desired surface properties and conditions in predetermined shapes and sizes at predetermined positions on the outer circumferential surface of the valve sheet And execute it. Particularly, in order to achieve the above-described " roughened area " having desired surface properties and conditions, it is preferable to appropriately adjust the irradiation time, output, frequency, etc. of the laser light.

When the laser beam is irradiated to the outer circumferential surface of the finished valve seat, the surface is melted and the molten molten metal is discharged to form the concave portion, while the discharged molten metal solidifies to form convex portions around the circumferential surface. Therefore, by adjusting the irradiation time, output, frequency, etc. of the laser light, it is possible to easily form the " rough surface area " having the desired surface properties and conditions.

The valve seat of the present invention is not particularly limited as long as it is a valve seat having the above roughed area. All materials for commercial valve seats such as spraying materials, sintered bodies and the like can be applied. Among them, an iron-based sintered alloy is preferable in terms of processability, excellent composition, and easy adjustment of characteristics to be provided as a valve seat.

A very preferable iron-based sintered alloy as the material for the valve seat of the present invention contains 0.4 to 1.5% of C, or further contains Ni, Co, Cr, Mo, V, W, Si, S, Mn , And B in a total amount of 40% or less, and has a base portion composition composed of the remaining Fe and inevitable impurities. The sintered body made of an iron-based alloy contains solid lubricant particles such as MnS, CaF ₂ and BN and Vickers hardness (HV) hardness of 500 to 1200 HV 0.1 in the matrix phase of the above- It is preferable to disperse the hard particles such as Mo-Si-Fe intermetallic compound particles, Mo-Si-Ni intermetallic compound particles, and Co group intermetallic compound particles. It goes without saying that particles for the purpose of improving machinability may be dispersed.

Next, a method for producing a sintered product of an iron-based alloy as a material for a valve seat of the present invention will be briefly described.

A graphite powder, a lubricant powder, or further a powder for an alloy or, further, a solid lubricant powder and / or a hard particle powder are compounded in an iron-based powder as a raw material so as to have the composition of the sintered body, Mixer, or the like to prepare a mixed powder (mixed powder). Subsequently, the obtained mixed powder is charged into a metal mold having a predetermined shape and pressed to form a green compact having a predetermined shape. Subsequently, these green compacts are sintered to obtain a sintered body. The sintering treatment is preferably carried out at 1100 to 1200 ° C in a reducing atmosphere or a non-oxidizing atmosphere, which is a conventional sintering method. The sintered body obtained in this manner is processed into cutting, grinding or the like to obtain a valve seat for an internal combustion engine of a predetermined size.

Example

A graphite powder, a hard particle powder and a solid lubricant powder were mixed with an iron-based powder (pure iron powder), mixed and kneaded to obtain a mixed powder. The graphite powder, the hard particle powder and the solid lubricant powder were mixed in an amount of 1.0% by mass with respect to the total amount of the iron-based powder, the graphite powder, the hard particle powder and the solid lubricant powder, respectively. Hard particles were Ni-Mo-Cr-Co hard particles having a Vickers hardness (HV) of 800 to 1200 HV. The solid lubricant particles were MnS.

Subsequently, the obtained mixed powder was filled in a metal mold and pressure-formed by a molding press to obtain a green compact having a valve seat (dimension:? 34 mm 占? 25 mm 占 8 mm). The obtained green compact had a density of 6.5 g / cm 3 to 7.1 g / cm 3. Subsequently, the green compact was subjected to sintering treatment at 1100 to 1200 占 폚 for 60 minutes in a reducing atmosphere to obtain a sintered body (a). The obtained sintered product (a) had a density of 6.2 g / cm 3 to 7.2 g / cm 3. The density was measured by the Archimedes method.

The sintered product (a) was subjected to cutting and grinding (finishing) to obtain a valve seat having a predetermined dimension (dimension: 32 mm x 25 mm x 6.0 mm). The surface roughness of the finished surface of the outer circumferential surface of the valve seat was 0.09 mu m to 0.15 mu m in terms of Ra in accordance with JIS Z 0601 (2001).

Subsequently, roughed areas of surface properties and conditions shown in Table 1 were formed on the outer peripheral surface of the finished valve seat in the form shown in Table 1. [ The formation of the roughened area is caused by a laser beam irradiation treatment or a shot blast treatment, or a scratch caused by spraying, sandpaper, or air hammer. In addition, the conventional example (valve sheet No. 1) was used in the case where no roughed area was formed.

The formed roughened area is schematically shown in Figs. 3, 4 and 5 to 10. Fig.

Fig. 3 shows a case where the roughened region shows a triangular shape in a state of being observed in a direction perpendicular to the outer circumferential surface, Fig. 3 (a) shows a case where the roughened region shows a convex portion, (b) shows a case where the roughened region represents the convex portion, and the mountain height continuously changes from the outer peripheral surface to the maximum mountain height along the press-in direction (the mountain height increases). Fig. 4 shows a case in which the roughened region has a rectangular shape when observed in a direction perpendicular to the outer peripheral surface, Fig. 4 (a) shows a case where the roughened region shows a convex portion, (b) shows a case in which the roughened region represents a concave portion, and a case in which the valley depth along the press-in direction continuously changes from the maximum valley depth to the outer circumferential surface (the valley depth is reduced). The height of the mountain and the depth of the bone were appropriately selected.

Fig. 5 shows a case in which the roughened region has a semicircular shape and the roughened region shows a convex portion in a state of being observed in a direction perpendicular to the outer circumferential surface, and the mountain height is constant along the push-in direction. 6 shows a case in which the roughened region has a star shape and the roughened region shows a convex portion in a state where the roughened region is observed in a direction perpendicular to the outer circumferential surface, and the mountain height is constant along the push-in direction.

7 and 8 are views observed in a direction perpendicular to the outer circumferential surface, in which the roughened region represents a triangular shape, the surface properties and the state of the roughened region indicate the concavo-convex mixing portion, Has a constant mountain height, and all of the concave portions have a constant valley depth based on the outer circumferential surface. Fig. 7 shows a case in which concavities and convexities formed by adjoining convex portions and concave portions extending in the circumferential direction in a direction perpendicular to the extending direction are regions having a plurality of rows in the pressing-in direction, and Fig. 8 is a cross- Convex portions and concave portions are adjacent to each other in the direction perpendicular to the extending direction (circumferential direction) as a region having a plurality of rows in the circumferential direction. In addition, the number of rows (plural rows) was changed according to the size of the roughened area and the mountain pitch.

Figs. 9 and 10 are views observed in a direction perpendicular to the outer circumferential surface, in which the roughened region shows a triangular shape, the surface property and the state thereof indicate the concave-convex mixing portion, And the concave portions all have a constant valley depth with respect to the outer circumferential surface. Fig. 9 shows a case where the concave portion and the convex portion of the concave-convex mixing portion are inclined by 45 占 with respect to the press-in direction, and Fig. 10 shows the case of concave- convex mixing portion with concave portions extending in a lattice- And concave portions are arranged in the press-fitting direction and the circumferential direction, respectively.

When the above-mentioned roughened region is formed by laser light irradiation processing, the irradiation pattern of the laser light, the irradiation time, the output, the frequency and the like are adjusted so as to become the " roughened region " . In some cases, the roughed area was formed by spraying, shot blasting, sanding, or air hammer treatment. In this case, the shot blast treatment, the sandpaper treatment, and the air hammer treatment were performed over the entire peripheral surface of the valve seat. In addition, a valve seat for holding a state of finish machining without performing laser light irradiation treatment, shot blast treatment, or the like has been used as a conventional example. Further, the height of the mountain and the depth of the bone were measured by using a non-contact type of offset ("one-shot 3D measurement macroscope" (trade name) (manufactured by KYENCE CO., LTD.)).

The valve seat thus obtained was measured for a dropout load (high-temperature dropout load) at a predetermined temperature (200 ° C) by using the high-temperature holdout force measuring apparatus shown in FIG. 2, .

The valve seat 1 to be evaluated was press-fitted into a cylinder head equivalent material 2 made of an aluminum alloy of a high temperature holding force measuring device. Then, the valve seat was heated to a predetermined temperature (200 DEG C) by the heating means (4) provided below the cylinder head equivalent material (2).

Subsequently, the valve seat 1 heated to a predetermined temperature was pressed using the pressing jig 3 to be released from the cylinder head equivalent material 2. The falling load L at that time was measured by a load meter (not shown). With respect to the resulting exudate load, the exudation resistance of each valve seat was calculated by calculating the standard value (1.00) of the conventional example. The obtained results are shown in Table 1.

[Table 1]

[Table 2]

In all of the embodiments of the present invention, as compared with the conventional example in which there is no roughened area, the falling load is increased and the durability is improved. On the other hand, in the comparative example deviating from the scope of the present invention, there is no change in the falling load as compared with the conventional example in which there is no roughed area.

1: Valve seat 2: Cylinder head equivalent material
3: pressurizing jig 4: heating means
10: High temperature force measuring device

Claims (13)

1. A valve seat which is press-fitted into a cylinder head made of a light metal alloy of an internal combustion engine,
Wherein at least one of the outer circumferential surfaces of the valve seat is provided with a convex portion having a mountain height of 5 占 퐉 to 80 占 퐉 and / or a depth of 5 占 퐉 to 100 占 퐉 on the basis of the outer circumferential surface in the press- Wherein the roughened region has a total area ratio of not less than 0.3% with respect to the entire area of the outer circumferential surface
Valve seat with excellent durability. The method according to claim 1,
Wherein the convex portion is an area having a tilted peak height continuously or stepwise increasing from the reference to the maximum peak height along the push-in direction with the peak height of the convex portion as a reference,
Valve seat. The method according to claim 1,
Characterized in that the concave portion is a region having a tapered valley depth in which the valley depth of the concave portion continuously or stepwise decreases from the maximum valley depth to the reference along the press-in direction with reference to the outer circumferential surface
Valve seat. The method according to claim 1,
Wherein the roughening region includes a concavo-convex mixing portion having concavities and convexes adjacent to the convex portion extending in the press-fit direction and a plurality of rows of concavities and convexities in the direction perpendicular to the press-fit direction, and / And a concave-convex mixing portion having a plurality of rows in a direction perpendicular to the circumferential direction
Valve seat. 5. The method of claim 4,
And the direction in which the concave portion and the convex portion extend in the concave-convex mixing portion is a direction having an angle in the range of more than 0 DEG and less than 90 DEG with the push-in direction
Valve seat. 5. The method of claim 4,
Wherein the roughened region has a lattice-like concave portion formed by combining a concave portion of a plurality of rows in which the concave-convex mixing portion extends in a predetermined direction and a plurality of concave portions in a plurality of rows extending in a direction perpendicular to the predetermined direction, And a convex portion formed in the lattice.
Valve seat. 7. The method according to any one of claims 4 to 6,
Wherein the convex portion is a convex portion having a mountain height of 5 占 퐉 to 80 占 퐉 with respect to the outer circumferential surface and the concave portion is a concave portion having a valley depth of 5 占 퐉 to 100 占 퐉 with respect to the outer circumferential surface To
Valve seat. 8. The method according to any one of claims 4 to 7,
Wherein the concavo-convex mixing portion has irregularities having a pitch of 1 占 퐉 to 600 占 퐉 which is a distance between two adjacent convex portions in a cross section perpendicular to the extending direction
Valve seat. 9. The method according to any one of claims 4 to 8,
The mountain height of convex portions in a plurality of rows of the concavo-convex mixing portion increases constantly with reference to the outer circumferential surface or increases along the press-in direction from the reference
Valve seat. 10. The method according to any one of claims 1 to 9,
Wherein the rough surface region is observed in a direction perpendicular to the outer circumferential surface to show any one of a triangular shape, a square shape, a circular shape, a semicircular shape, and a star shape.
Valve seat. 11. The method of claim 10,
Wherein the roughened region forms the convex portion or the concave portion only in the periphery of any one of the triangular shape, the rectangular shape, the circular shape, the semicircular shape, and the star shape.
Valve seat. 12. The method according to any one of claims 1 to 11,
Characterized in that the roughened region is formed at each position of equal intervals in the circumferential direction
Valve seat. 13. The method according to any one of claims 1 to 12,
Characterized in that the valve seat is an iron-based sintered alloy
Valve seat.

Images